The BTS3900 developed by Huawei is an indoor macro BTS. The BTS3900 mainly consists of the BBU and RFU. Compared with traditional BTSs, the BTS3900 ...
FOREWORD Names of the Trainees Students: ASRI Abdellatif & BAOUCH Mustapha
Title of the work: DEPLOYEMENT OF UMTS AT 900 MHZ BAND (U900)
Host institution : Huawei Technologies Morocco Av. Annakhil, imm. High Tech, 4°ét. Hay Ryad, Rabat - Phone: 0537569199
Home institution: FACULTY OF SCIENCES TETOUAN
Professional Supervisor: Eng. Mr. BEN MAATI Achraf Implementation Manager, Huawei Wireless Project for IAM Account – Morocco
Academic Supervisor: Prof Mr. MRABET Othman Professor at FACULTY OF SCIENCES TETOUAN
Start and end date of the internship:
From February to June 2018
Financial support: UNPAID internship
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ACKNOWLEDGEMENTS First & foremost of all, We Wish to Express our heartiest gratitude and total devotion to almighty Allah for blessing us with the ability, Strength and Patience as well as keeping us active in performing our project related tasks successfully. We want also to thank our beloved Parents, This couldn’t be possible without the support of them and our friends along this period. We are very appreciated to Eng. Mr. BEN MAATI Achraf our supervisor at Huawei Technologies Rabat, who trusted our capabilities by giving us the opportunity to join His Team, and always pushed us to give more, Mr. BEN MAATI Achraf gave us very in-time valuable instructions and put us in contact with experts in the field like Mrs. SKIR Sara, RF Engineer at Huawei, who gave us extensive guidance, And Also Eng. Mr. ELYAMINE Omar Who Guide us on the practical aspect regarding many practical issues. We also would like to express our gratitude to Prof. MRABET Othman for his permission to be our academic supervisor and more importantly for his enthusiastic encouragements and precious instructions during our internship period. He gave us in-time feedback on our research and helped us throw all those two years of Master Studies and organize an interesting presentation in which we could present our ideas and achievements to other professors and researchers of the faculty. Throughout the internship, we did not only gain a lot of knowledge but more importantly, we also had a great chance to sharpen our skills in a professional working environment. Not less important than the Telecommunication technologies that we have learnt is the communication skills that we have been trained and practiced through giving presentations, discussing with the supervisors, experts in the field and other staffs within the company. We have also learnt many things about the Chinese culture whose benefits are far beyond what we could learn in a normal project. In short, I would like to thank all the staff of Huawei Technologies Rabat who provided us the means to spend our internship in the best conditions and for introducing us to this great opportunity in which we have developed ourselves both academically, professionally and socially. And may all the members of the jury find here our gratitude for agreeing to judge our work, We would not forget in our thanks all the teaching staff of Faculty of Science Tetouan, for the prodigious training, and all those who have contributed, from near or far, to the accomplishment of this work, find the expression of our most sincere thanks.
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ABSTRACT The operator “ Maroc Telecom” detected several problems with the existing 3G service which is UMTS2100 technology such as the limitation of the frequency band of 2100MHz, the increasing number of Moroccan mobile subscribers, the high demand of high-speed data services, poor coverage in rural areas and inadequate indoor coverage which requires the installation of more sites in order to improve it, this is why Huawei proposed a new solution called UMTS900 technology that will address all these problems. This technology represents the latest evolution of UMTS, and is part of the 3GPP family. It enjoys the same ecosystems that ensured the success of GSM and UMTS technology that promises better coverage, and allows greater flexibility in the allocation of the frequency spectrum to meet the exponential growth of mobile data traffic. HUAWEI has a rich experience in the "900MHz re-farming " given its participation in the deployment of most UMTS 900 networks around the world. Indeed, in order to implement such networks, the frequency resources of the GSM 900 must be reallocated for the use of the 3G. Therefore, the aim of our project is to study the U900 re-farming solution for the client Maroc Telecom and a simulation of its implementation of the UMTS 900 technology will be done to prove its benefits considering the level of coverage, Indoor penetration and others KPI, our case study is the city of Asilah that was the first city in morocco that Maroc Telecom with Huawei deploy U900.
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RESUME L'opérateur "Maroc Telecom" a détecté plusieurs problèmes avec le service 3G existant qu'est la technologie UMTS2100 tels que la limitation de la bande de fréquence de 2100MHz, le nombre croissant d'abonnés mobiles marocains, la forte demande de services de données haut débit, zones rurales et une couverture intérieure insuffisante qui nécessite l'installation de plus de sites afin de l'améliorer, c'est pourquoi Huawei a proposé une nouvelle solution appelée technologie UMTS900 qui permettra de résoudre tous ces problèmes. Cette technologie représente la dernière évolution de l'UMTS et fait partie de la famille 3GPP. Il bénéficie des mêmes écosystèmes qui ont assuré le succès de la technologie GSM et UMTS qui promet une meilleure couverture, et permet une plus grande flexibilité dans l'attribution du spectre de fréquences pour répondre à la croissance exponentielle du trafic de données mobiles. HUAWEI a une riche expérience dans le "900MHz re-farming" compte tenu de sa participation au déploiement de la plupart des réseaux UMTS 900 dans le monde. En effet, pour mettre en œuvre de tels réseaux, les ressources de fréquence du GSM 900 doivent être réallouées pour l'utilisation de la 3G. Ainsi, notre projet vise à étudier la solution de ré-élevage U900 pour le client Maroc Telecom et une simulation de sa mise en œuvre de la technologie UMTS 900 sera faite pour prouver ses bénéfices compte tenu du niveau de couverture, pénétration intérieure et autres KPI, notre étude de cas est la ville de Asilah qui fut la première ville au Maroc que Maroc Telecom avec Huawei déploie U900.
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ملخص تواجه شركة إتصاالت المغرب حاليا العديد من المشاكل مع خدمة الجيل الثالث المعروفة بتكنولوجيا UMTS 2100والمتمثلة في انحصار مجال الترددات ، 2100 MHzتزايد عدد مستخدمي الجيل الثالث ،ضعف التغطية في المناطق الريفية ونقص التغطية في األماكن المغلقة الشيء الذي يتطلب تركيب المزيد من مواقع الراديو من أجل تحسينها ،وكدلك تزايد عدد مستخدمي خدمة الهاتف المحمول الشيء الذي ترتب عنه ارتفاع الطلب على خدمات البيانات عالية السرعة ،و بناء على هذه األسباب هواوي اقترحت حال جديدا بسمى
تكنولوجيا UMTS900التي من شأنها معالجة كل هذه المشاكل. تمثل هذه التكنولوجيا أحدث تطورا للجيل الثالث ،وهي جزء من عائلة .3GPPوتتمتع بنفس النظم الخصائص التي ضمنت نجاح GSMو UMTSوالتي تعد تغطية أفضل ،وتتمتع بالمرونة في تخصيص مجال التردد المناسب بهدف مواجهة النمو المتسارع للبينات
المتنقلة. هواوي تتوفر على خبرة غنية في اعادة توزيع ال U900نظرا لمشاركتها في انشاء اغلب شبكات ال UMTS 900حول العالم وفي الواقع ومن أجل انشاء هذه الشبكات يجب اعادة تخصيص موارد التردد للشبكة الجيل الثاني من اجل استخدامها في الجيل الثالث وتعتبر
هواوي رائدة في مجاالت االتصاالت والسباقة الستعمال هذه التكنولوجيا على مستوى العالم. لذلك ،فإن الهدف من مشروع تخرجنا هذا هو دراسة اعادة تهيئ U900لصالح اتصاالت المغرب ،وسنقوم بإجراء محاكاة لتطبيق تكنولوجيا ال U900إلثبات فوائدها مع األخذ بعين االعتبار مستوى التغطية ،االختراق الداخلي اإلشارة وغيرها من مؤشرات األداء الرئيسية ،وقمنا بدراسة ومحاكاة لهذه التكنولوجيا على مستوى مدينة أصيلة التي كانت أول مدينة في المغرب تقوم فيها اتصاالت المغرب مع هواوي بنشر U900وقمنا بعمل مقارنة قبل وبعد نشر الـ. U900
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Abbreviation M
A ARFCN: Absolute Radio Fequency Channel Number
AuC: Authentication Center
MS:
Mobile Station
MSC: Mobile Switching Center
B
N
BCCH: Broadcast Control Channel BSC:
Base Station Controller
BTS:
Base Transceiver Station
NCC: Network Color Code NSS: Network SubSystem O
C CDMA: Code Division Multiple Access CI:
Cell Identifier
CS:
Circuit Switched
OSS: Operation SubSystem P
D
PS: Packet Switched PSC: Primary Scrambling Code
DCS: Digital Cellular System DT: Drive Test
R RNC:
Radio Netword Controller
RSCP:
Received Signal Code Power
E EIR: Equipment Identity Register F
RxLev: Received Signal Level S
FDMA: Frequency Division Multiple Access
G GSM: Global System for Mobile Communication
3GPP: Generation Partnership Project H
SSV:
Single Site Verification T
TCH: Trafic Channel TDMA: Time Division Multiple Access
HLR: Home Location Register U HO: Handover UE: User Equipement K V KPI: Key Performance Indicator VLR: Visitor Location Register L LAC: Location Area Code LTE: Long Term Evolution
W WCDMA: Wideband Code Division Multiple Access 6
Figures List Figure 1: Worldwide presence of HUAWEI ............................................................................ 17 Figure 2: Core Values scheme of Huawei ................................................................................. 19 Figure 3: Local organization of the company........................................................................... 21 Figure 4: Timeline of The Internship ........................................................................................ 24 Figure 5: GSM Architecture ...................................................................................................... 28 Figure 6: The NSS structure ...................................................................................................... 29 Figure 7: FDMA Access Method ............................................................................................... 31 Figure 8: TDMA Access Method ............................................................................................... 31 Figure 9: CDMA Access Method ............................................................................................... 31 Figure 10: Channels types .......................................................................................................... 33 Figure 11: GSM Handovers ....................................................................................................... 34 Figure 12: UMTS Architecture.................................................................................................. 35 Figure 13: Core Network Components ..................................................................................... 36 Figure 14: Soft Handover ........................................................................................................... 39 Figure 15: Softer Handover ....................................................................................................... 39 Figure 16: Hard Handover ......................................................................................................... 39 Figure 17: BTS Structure ........................................................................................................... 41 Figure 18: BTS location .............................................................................................................. 41 Figure 19: BTS3900 Hardware Structure (-48V) .................................................................... 42 Figure 20: BBU3900 Components ............................................................................................. 43 Figure 21: BBU3900 Slots .......................................................................................................... 44 Figure 22: BBU Cables ............................................................................................................... 44 Figure 23: GTMU Board ............................................................................................................ 45 Figure 24: WMPT Board ........................................................................................................... 45 Figure 25: WBBP Board ............................................................................................................ 45 Figure 26: UPEU Board ............................................................................................................. 46 Figure 27: DUDC Module .......................................................................................................... 47 Figure 28: FAN Box .................................................................................................................... 47 Figure 29: frequency band allocation and technology deployment for the operator ........... 52 Figure 30: impact of UMTS 900 ................................................................................................ 52 Figure 31: Coverage against the same power of emission and the indoor coverage ............. 53 Figure 32: Edge frequency allocation mode ............................................................................. 55 Figure 33: Sandwich frequency allocation mode ..................................................................... 56 Figure 34: UMTS non-standard separation configuration ..................................................... 58 Figure 35: Frequency distribution ............................................................................................ 59 Figure 36: Extend 3G Coverage ................................................................................................ 60 Figure 37: Improve 3G Coverage .............................................................................................. 60 Figure 38: Initial 3G Roll-out .................................................................................................... 61 7
Figure 39: Extend 3G Coverage ................................................................................................ 61 Figure 40: What and where the potential problems are ......................................................... 62 Figure 41: Types of interference between GSM and UMTS................................................... 63 Figure 42: Minimization of carrier separation interferences ................................................. 63 Figure 43: Buffer Zone Design Process ..................................................................................... 64 Figure 44: Location of the Buffer Zone .................................................................................... 65 Figure 45: frequency allocations................................................................................................ 65 Figure 46: The traffic migration to the 900 MHz band Process ............................................. 67 Figure 47: Load balancing after the introduction of UMTS 900............................................ 67 Figure 48: GSM900 frequency band used by Maroc Telecom ............................................... 69 Figure 49: Base Station Identity Code ...................................................................................... 70 Figure 50: Optimization process cycle ...................................................................................... 71 Figure 51: Drive Test Tools ........................................................................................................ 73 Figure 52: The path of SSV Test ............................................................................................... 74 Figure 53: G900 sites in the city of Asilah ................................................................................ 77 Figure 54: 1800 DCS Sites in the city of Asilah ........................................................................ 77 Figure 55: Zone U900 et Zone Tampon de la ville d'Asilah .................................................... 78 Figure 56: Recovery Zones -Asilah- .......................................................................................... 79 Figure 57: Configuring the BTS with U900 .............................................................................. 83 Figure 58: DT Rxlev int Asilah city ........................................................................................... 84 Figure 59: DT Rxlev in Highway ............................................................................................... 85 Figure 60: DT Rxqual in Asilah city ......................................................................................... 86 Figure 61: DT Rxqual in Highway ............................................................................................ 87 Figure 62: Distribution of measurement samples U900 and U2100 ....................................... 87 Figure 63: RSCP DT results in City and Highway .................................................................. 89 Figure 64: Ec / Io DTs Results in the city and highway .......................................................... 91 Figure 65: KPI CSR Graph ....................................................................................................... 92 Figure 66: “TCH Call Drop Rate” KPI GRAPH ..................................................................... 92 Figure 67: Outgoing Inter-cell Handovers Success Rate KPI Graph .................................... 93 Figure 68: Incoming Inter-cell Handovers Success Rate KPI Graph .................................... 93 Figure 69: PS CSSR KPI Graph................................................................................................ 94 Figure 70: CS CSSR KPI Graph ............................................................................................... 94 Figure 71: Call Drop Rate Voice KPI Graph ........................................................................... 95 Figure 72: Call Drop Rate Data KPI Graph ............................................................................ 95
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Tables List Table 1 : Evolution Technologie ................................................................................................ 27 Table 2 : The GSM Interfaces.................................................................................................... 30 Table 3: GSM Standards ............................................................................................................ 32 Table 4: UMTS Interfaces .......................................................................................................... 37 Table 5: Advantages and Desadvantages of 2G/3G ................................................................. 40 Table 6: BTS Abreviations ......................................................................................................... 42 Table 7: A comparative table between the two modes ............................................................ 57 Table 8: U900 parameters and thresholds ................................................................................ 74 Table 9: TRX G900 configuration before and after re-farming............................................. 79 Table 10: Rxlev references ......................................................................................................... 84 Table 11: City Static Rxlev......................................................................................................... 85 Table 12: Highway Static Rxlev................................................................................................. 85 Table 13: Range of Signal Quality............................................................................................. 86 Table 14: RSCP power range..................................................................................................... 88 Table 16 : RSCP statistics in the city ........................................................................................ 89 Table 17 : RSCP Statistics in the highway................................................................................ 89
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Summary GENERAL INTRODUCTION .......................................................................................................... 14 Chapter 1: The Host Company Presentation......................................................................... 16 I.
Huawei Technologies Presentation ............................................................................................ 17
II.
What Huawei offer to the world?............................................................................................... 17
III.
What Huawei stand for? ........................................................................................................ 19
IV.
Core Values ......................................................................................................................... 19 Huawei Morocco...................................................................................................................... 20
V. VI.
Huawei Product and Services ................................................................................................ 21
VII.
Project Context..................................................................................................................... 22
VII.1
The problematic issue.................................................................................................. 22
VII.2
WIRELESS Department Presentation .......................................................................... 22
VII.3
Project overview .......................................................................................................... 22
VII.4
Specifications ............................................................................................................... 23
VII.5
Project Planning ........................................................................................................... 23
Chapter 2: 2G/3G Network.............................................................................................................. 25 I.
History .................................................................................................................................... 26
II.
Global System for Mobile Communications (GSM).................................................................... 27 II.1
Introduction .................................................................................................................. 27
II.2
Architecture of GSM network .................................................................................... 27
II.2.1
Mobile Station ................................................................................................................... 28
II.2.2
Base station Sub-System (BSS) ........................................................................................ 28
II.2.3
Network Sub-System (NSS).............................................................................................. 29
II.2.4
Operations Support System (OSS) .................................................................................. 29
II.3
Interfaces ...................................................................................................................... 30
II.4
Access methods .......................................................................................................... 30
II.4.1
FDMA................................................................................................................................ 31
II.4.2
TDMA ............................................................................................................................... 31
II.4.3
CDMA ............................................................................................................................... 31
II.5
The frequency spectrum............................................................................................. 32
II.6
GSM Handover ............................................................................................................. 33
III.
Universal Mobile Telecommunications System (UMTS) ......................................................... 34
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III.1
Introduction .................................................................................................................. 34
III.2
Architecture of UMTS network .................................................................................... 34
III.2.1
User Equipment (UE) ...................................................................................................... 35
III.2.2
Radio Network Subsystem (RNS) ................................................................................... 35
III.2.3
Core Network ................................................................................................................... 36
III.3
Interfaces ...................................................................................................................... 37
III.4
Access methods .......................................................................................................... 38
III.4.1
WCDMA ............................................................................................................................ 38
III.5
The frequency spectrum............................................................................................. 38
III.6
UMTS Handover ............................................................................................................ 39 Advantages and disadvantages of 2G and 3G.......................................................................... 40
IV.
BTS 3900 ................................................................................................................................ 40
V.
V.1
Definition ....................................................................................................................... 40
V.2
BTS location ................................................................................................................... 41
V.3
BTS 3900 Hardware components ............................................................................... 41
V.3.1
BBU3900 ............................................................................................................................ 43
V.3.2
MRFU Module................................................................................................................... 46
V.3.3
DUDC Module ................................................................................................................... 46
V.3.4
FAN Box ............................................................................................................................. 47
Conclusion ........................................................................................................................... 48
VI.
Chapter 3: U900 Deployment ........................................................................................................... 49 I.
Presentation of the U900 Technology? ....................................................................................... 50
II.
U900 Solution .......................................................................................................................... 50 II.1
Why Choosing U900?................................................................................................... 50
II.2
Advantages of U900 .................................................................................................... 51
II.3
Key Problems Concerned With U900 and Their Solutions ....................................... 53
II.3.1
Mutual effect on networks ................................................................................................ 53
II.3.2
Interoperability between U900 and existing network .................................................... 54
II.4
Re-farming .................................................................................................................... 54
II.4.1
What is Re-farming?......................................................................................................... 54
II.4.2
Challenges of the GU 900 MHz Re-farming ................................................................... 54
II.5
Frequency Allocation between GSM and UMTS Networks.................................... 55
II.5.1
Edge Frequency Allocation Mode.................................................................................... 55
II.5.2
Sandwich Frequency Allocation Mode [Recommended By Huawei] ........................... 56
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II.6
Deployment Scenarios ................................................................................................ 59
II.6.1
Scenario 1 [Extend 3G Coverage in Sub-urban & Rural]............................................. 59
II.6.2
Scenario 2 [Improve 3G Coverage in Urban area] ........................................................ 60
II.6.3
Scenario 3 [Initial 3G Roll-out In All areas] ................................................................... 61
Interferences analysis ............................................................................................................ 62
III. III.1
Types of interferences ................................................................................................. 62
III.2
Interference reduction ................................................................................................ 63
III.2.1
Minimization of carrier separation interferences .......................................................... 63
III.2.2
Minimize interference by scheduling buffer zones Solution ......................................... 64
III.2.3
Summary ............................................................................................................................ 65
Traffic Migration .................................................................................................................. 66
IV. IV.1
Release of 5 MHz from the 900 MHz band ............................................................... 66
IV.2
Traffic balance between 900MHz and 1800MHz .................................................... 67
IV.3
GSM900 traffic migration to the UMTS900 & UMTS2100 .......................................... 68
U900 Project Process................................................................................................................ 68
V.
V.1
U900 Planning Process ................................................................................................. 68
V.1.1
U900 Frequency Plan ........................................................................................................ 68
V.1.2
Buffer Zone Planning........................................................................................................ 69
V.1.3
DCS 1800 Sites Planning .................................................................................................. 69
V.1.4
U900 Sites Planning .......................................................................................................... 71
V.2
U900 Optimization Process.......................................................................................... 71
V.2.1
Drive Test optimization .................................................................................................... 72
Conclusion ........................................................................................................................... 75
VI.
Chapter 4: Case study ...................................................................................................................... 76 I.
II.
Steps and methods of UMTS deployment .................................................................................. 77 I.1
Existing configuration of the 2G ................................................................................. 77
I.2
Buffer Zone Planning.................................................................................................... 78
I.3
GSM Reduced configuration of test sites ................................................................. 79
I.4
U900 Hardware Integration in SRAN Sites ................................................................. 83
Drives Tests ............................................................................................................................. 84 II.1 Drive Test Statistics and Measurements for 2G ............................................................. 84 II.1.1 Statistics and distribution of received Rxlev signal level before and after U900 activation............................................................................................................................................ 84 II.1.2
Statistics and distribution quality (RxQual) before and after activation of the U900 86
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II.2 Statistics and Measurement of the Drive Test for 3G (Before and after the integration of the U900) ......................................................................................................... 87 II.2.1
RSCP level statistics and measurements ......................................................................... 88
II.2.2
Ec / Io Statistics and measurement .................................................................................. 90
KPI Analysis ........................................................................................................................ 91
III. III.1
2G KPI ............................................................................................................................ 91
III.1.1
2G Voice CSSR (Call Setup Success Rate) ..................................................................... 91
III.1.2.
TCH Call Drop Rate ......................................................................................................... 92
Ill. 1. 3
Handover Success Rate ..................................................................................................... 93
III.2. 3G KPI ................................................................................................................................ 94
IV.
III.2.1
PS & CS Setup Success Rate ............................................................................................ 94
III.2.2.
Call Drop Rate (Voice and Data) ..................................................................................... 94
Conclusion ........................................................................................................................... 95
CONCLUSION & PERSPECTIVES ................................................................................................. 96 Annex ........................................................................................................................................... 97 Bibliography and Webography:............................................................................................... 99 Huawei Internal documentation ........................................................................................... 99 Books ........................................................................................................................................ 99 Sites ........................................................................................................................................... 99
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GENERAL INTRODUCTION Telecommunications is a sector that is still evolving from 2G networks to 3G then 4G networks. However, the saturation of 2G networks and their limitations in terms of throughput, has led the players in the telecommunications field to standardize a third generation represented by the UMTS standard which provides an improvement in the throughput to support new services with good transmission quality. Voice and data. However, with increasing demand and subscribers increasing, this technology cannot meet all needs. Therefore, it was necessary to push development towards other improvements for increase the capacity of the networks, namely the fourth generation LTE providing an improvement in radio data rate and quality. But despite all these improvements, Morocco has always met problems with 3G coverage in indoor and in rural areas. In order to solve these problems, UMTS technology has been improved since it is used by a large number of users despite the better performance of the fourth generation compared to the third generation. We then sought to combine the high data rate of UMTS2100 with the best GSM coverage to develop a new technology that can fully utilize spectrum resources and meet data service requirements. We are talking about the UMTS900. As a supplier of telecommunication equipment, HUAWEI has been chosen by the Maroc Telecom customer operator to lead the planning and optimization of this solution, since it is aware that the realization of UMTS on the frequency band 900 MHZ remains a fundamental challenge to save its investments by reducing the number of sites to deploy, and to ensure a good quality of service to users. It is in this perspective that our graduation project is carried out within the RNP / RNO department "Radio Network Planning / Optimization". The main goal of our and optimize the UMTS 900 solution in the city of Asilah.
project is to master the concepts of planning and put them into practice by activating this
This graduation project has a technical dimension that will help us to implement and practice our theoretical knowledge acquired during our training and enrich our skills in the field of telecommunications. Based on this perspective this report consists of five chapters and is organized as follows:
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The first chapter, will be devoted to the presentation of the host organization as well as the general context of project detailing the problem and the specifications. In the second chapter we deeply covers the basics, which are necessary to understand the U900 is GSM & UMTS concept, architecture, channels. And later in this chapter we give an overview about the BTS 3900 Series, its components and the function of every piece of it. The third chapter explain the UMTS 900 solution at the theoretical level, and presents a detailed study of the reuse of 900 MHz frequencies for 3G (re-farming) as well as an analysis of possible frequency allocation solutions and implementation of the UMTS 900 network. The study in this section also includes the analysis of interference caused by the introduction of UMTS 900, and also the process of planning and optimization. The fourth chapter and the last one, will be dedicated to make a comparison of the state of the network in coverage term and signal quality. The purpose of this comparison is to demonstrate the importance of the newly deployed technology.
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Chapter 1: The Host Company Presentation
This chapter give a presentation about Huawei Technologies Company where this work have been performed, it also give an overview about the internship project context.
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I.
Huawei Technologies Presentation
Founded in 1987, Huawei is a leading global information and communications technology (ICT) solutions provider. Huawei provide telecom carriers, enterprises, and consumers with competitive ICT solutions, products, and services. Huawei work in more than 170 countries and regions, serving over one-third of the world’s population. Among 180,000 employees, there are more than 160 different nationalities with a localization rate of almost 70%.
Figure 1: Worldwide presence of HUAWEI
II.
What Huawei offer to the world?
Huawei create value for its customers. And Together with telecom carriers, Huawei has built more than 1,500 networks, helping connect over one-third of the world’s population. Huawei with its partners serve government and public utilities, as well as enterprise customers in sectors like finance, energy, transportation, and manufacturing. Huawei help organizations and industries go digital by providing them with open, flexible, and secure ICT infrastructure platforms that promote greater synergy between devices, networks, and the cloud. Huawei also provide enterprise customers with stable, reliable, and secure cloud services that evolve 17
with their needs. and with Huawei's smartphones and other smart devices, Huawei improve people’s digital experience in work, life, and entertainment. Huawei promote industry development. Huawei advocates openness, collaboration, and shared success. Through joint innovation with its customers, partners, and peers, Huawei expanding the value of information and communications technology in service of a more robust and symbiotic industry ecosystem. Huawei is an active member of more than 360 standards organizations, industry alliances, and open source communities, where Huawei work together on mainstream standards and lay the foundation for shared success. Huawei have also joined forces with industry partners to innovate in emerging domains like cloud computing, software-defined networking (SDN), network functions virtualization (NFV), and 5G. Together, they are driving the industry forward. Huawei drive economic growth. Huawei generates tax revenues, provides local employment opportunities, and stimulates the development of the ICT value chain in every country where they operate. Furthermore, Huawei deliver innovative ICT solutions that drive the digital transformation of all industries, fostering economic growth and greatly improving quality of life. We enable sustainable development. As a responsible corporate citizen, Huawei has made a significant contribution to bridging the digital divide, leaving our mark in places as remote as Mount Everest and the Arctic Circle. Huawei keenly aware of the importance of telecommunications in emergency response situations. Having faced Ebola-affected areas in West Africa, nuclear contamination after the Japanese tsunami, and the massive earthquake that struck Sichuan, China, and Huawei hold fast to restore communications networks and ensure the reliable operation of essential telecoms equipment in disaster zones. To further promote sustainability, Huawei prioritize low-carbon and environmental protection throughout all planning, design, R&D, manufacturing, delivery, and O&M activities, providing its customers with top-of-the-line products and solutions that save energy and reduce environmental impact. As for people, Huawei help develop the next generation of local ICT talent with our global Seeds for the Future program, where Huawei work with young talent across 108 countries and regions to transfer knowledge, cultivate understanding and greater interest in the ICT industry, and encourage broader involvement in the digital community. Huawei provide dedicated people with a strong growth platform. Inspiring dedication is one of Huawei’s core values, and it manifests itself in many ways. We assess employees and select managers based on their contribution, as well as the extent of their responsibilities. Huawei provide its teams with a global development platform, giving young team members the opportunity to shoulder greater responsibilities and accelerate their careers. In this way, Huawei have enabled over 100,000 Huawei people to yield ample returns and gain memorable life experience. [11]
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III. What Huawei stand for? For the past 30 years Huawei have maintained an unwavering focus, rejecting shortcuts and easy opportunities that don’t align with our core business. With a practical approach to everything Huawei do, Huawei concentrate their efforts and invest patiently to drive technological breakthroughs. This strategic focus is a reflection of their core values: staying customer-centric, inspiring dedication, persevering, and growing by reflection. The digital era has been generous. Huawei will make the most of this historic opportunity, and boldly forge ahead to build a fully connected, intelligent world. [11]
IV. Core Values Huawei works with six fundamental values:
Figure 2: Core Values scheme of Huawei
Customer first: Huawei create long-term value for customers by being responsive to their needs and requirements.
Dedication: This include every effort Huawei makes to create value for customers and improve their capabilities.
Continuous Improvement: Huawei actively listen and learn to become better partner for its customers.
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Openness & Initiative: Huawei pursue customer-centric innovations in an open manner, believing that business success is the ultimate measure of the value of any technology, product, solution, or progress improvement.
Integrity: Huawei believes that honesty and integrity are the most valuable assets to win customer’s trust and respect.
Teamwork: Success comes through teamwork. Huawei lays the foundation for successful cross-cultural collaboration, streamlined inter-departmental cooperation and efficient processes.
Its values able the company to provide efficient services to its clients and having homogeneous teams with great capacities and motivation.
V.
Huawei Morocco
The year 2004 saw the recording of HUAWEI Technologies MOROCCO SARL, which employs more than 400 employees, 70% Moroccans. The firm has in its customer portfolio major national operators like “Maroc Telecom (IAM)”, INWI CORPORATE, and Orange. She has operates more than 200 telecommunications projects in Morocco. Huawei Morocco currently have leading position in the Moroccan telecommunication market thanks to the collaboration with the main Moroccan operators: Maroc-Télécom, Orange and Inwi. In 2010, the Moroccan subsidiary has achieved $200 million in terms of sales revenue, 80% thanks to telecommunications. The Moroccan subsidiary employs 400 people 70% of them are Moroccans, and currently occupies a lead position in the Moroccan telecommunication market thanks to a close collaboration with the main Moroccan operators, “Maroc Telecom”, “Meditel” and “Inwi”, by the realization of innovative projects like the METRO IP network, the high speed ADSL, IPTV, Single RAN for the deployment of 3G & 4G, MSAN Huawei, and SingleOSS. Huawei Morocco is organized in several departments including: 1
Network Deployment: Mainly responsible for network deployment and coordination with subcontractors.
2
Technical Support: Take charge of network maintenance.
3
Training: Deals with the customer's training requirements and instruments in this regard.
4
Logistics and Spares: Deals with logistics and material delivery service.
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Figure 3: Local organization of the company
VI. Huawei Product and Services Today, Huawei is a provider of digital solutions in terminals, networks and cloud, for operators, businesses and consumers. Its products and solutions are deployed in more than 170 countries.
Digital Home (IPTV) Unified Communications and Collaboration Single RAN: whose function is to merge all the radio communication capabilities of a cellular network (GSM, UMTS/HSPA +, LTE ...) into one equipment, and this allows operators to simplify the integration of technological innovations. The solution allows operators to optimize their essential assets globally, including sites, spectrum, users, and staff. MSAN Huawei: implementation of the Huawei MSAN MultiService Access Node solution. Metro Optical Transport Network: Metro OTN unifies the transportation architecture and provides carriers with ubiquitous transport channel and increased bandwidth for services such as broadband access, mobile video, private line, and cloud connectivity. SingleOSS: Huawei's SingleOSS achieves synergy between networks inter-domains (radio / transmission / core access) and inter-technology networks (GSM / CDMA / UMTS / Wi-MAX / LTE FDD / TDD) while managing the global resources of the network.
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SingleCORE: Provides a single core network solution to enable smooth network evolution and smart operations, while providing an enhanced user experience. U900: UMTS in band of 900MHz, which forms the bottom of our subject. [11]
VII. Project Context VII.1
The problematic issue
Due to the explosive demand of subscribers for data services and the decrease in the use of voice services, several operators have considered the transfer of 3G to the 900 MHz band that is dedicated to GSM, for better coverage at low cost and therefore increase the number of subscribers to promote better competition at the economic level. In this context the operator “Maroc Telecom” has decided to deploy UMTS900 technology in very dense urban areas, indoor areas and in rural areas where people still do not have access to telecommunications services or the Internet.
VII.2
WIRELESS Department Presentation
The department RNP/RNO (Radio Network Planning and Optimization) is part of the technical department “Wired and Wireless Broadband Access”. Its mission is to make the monitored network radio as well as planning and optimization of the GSM, UMTS, LTE network and the new UMTS90 project in order to improve and maintain good quality of service
VII.3
Project overview
The UMTS900 solution uses the GSM frequency band to deploy a UMTS network at a lower cost and with better coverage than the UMTS2100 network, because the low frequencies allow the waves to easily penetrate into the buildings, resulting in an improvement of the operator’s network, especially in very dense urban and rural areas. Users get 3G services integrated on the same platform by re-using GSM network infrastructure such as antennas and sites by adapting them to the new standards so it will no longer be necessary to increase the number of sites, this will result in less expenditure on equipment. Our contribution to the project is to plan and optimize the U900 network in the Asilah city. The planning consists of planning the GSM900 / DCS1800 frequencies, the location of the buffer zone sites, also migrate the traffic to the DCS1800 in order to free part of the 900 MHz band where UMTS has been planned to be implemented and finally activate U900 technology. In order to compare network performance determined by the equipment manufacturer (Huawei) and its customer (Maroc Telecom) before and after the activation of U900 we are going 22
to do an analyzing of the KPIs. These performance keys or (Key Performance Indicators) reflect the state of the network (coverage, quality, handover success rate ...), The data collected by the DTs based on which more relevant actions will be proposed and finally the improvement of the performance of the network will be reported in the form of an optimization report.
VII.4
Specifications
In order to answer the above problematic, objectives have been set. The main objective is to plan and optimize the city of Asilah to improve the quality of service according to the requirements imposed by Maroc Telecom. So our contribution to the project is to carry out the following actions:
Study of 2G and 3G of the existing network
Study the BTS 3900 series
Study of U900 solution
Re-farming & traffic migration
Planning and optimization
The study of the architecture of Asilah network
Before / After Comparison
VII.5
Project Planning
Project planning is intended to provide reasonable predictions for the implementation of engineering and project management, these predictions are essential for effective project management. Among the project planning tools, we used the GANT chart, it is a tool to plan the project and make it easier to track progress. This diagram also makes it possible to visualize the sequence and duration of different tasks. Below is a visualization of all the tasks we performed during this internship and which are realized thanks to the tool "Tom's planner"
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Figure 4: Timeline of The Internship
Conclusion In this chapter, first we introduced Huawei Technologies and its various active sectors, then we introduce our internship Project, then the problematic issue as well as project planning. In the next chapter we are going to present 2G & 3G Network, and Single Ran Solution.
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Chapter 2: 2G/3G Network
This chapter includes the main characteristics of the 2G and 3G network, explaining its architecture and components, and an overview about the BTS 3900 series.
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I.
History
Nordic Mobile Telephone (NMT) is a mobile telephony standard specified by the Nordic Telecommunications Administrations from 1970. It was putting on service in 1981 to response to the congestion of existing mobile telephony networks at that time (ARP on the frequency 150 MHz in Finland and MTD on the frequency 450 MHz in Sweden, Norway and Denmark). This firstgeneration network has been opened in countries such as Sweden, Denmark, Norway, hence the name "Nordic" in its name. At the beginning of the 1990s, GSM, the Global System for Mobile Communications, triggered an unprecedented change in the way people communicate with each other. While earlier analog wireless systems were used only by a few, GSM is used worldwide by billions of people today. This has mostly been achieved by steady improvements in all areas of telecommunication technology and the resulting steady price reductions for both infrastructure equipment and mobile devices. The Universal Mobile Telecommunications System (UMTS) is a third‐generation wireless telecommunication system and followed in the footsteps of the Global System for Mobile Communications (GSM). Since GSM was standardized in the 1980s, huge progress had been made in many areas of telecommunications. This allowed system designers at the end of the 1990s to design a new system that went far beyond the capabilities of GSM. UMTS combines the properties of the circuit‐switched voice network with the properties of the packet switched data network and offers a multitude of new possibilities compared to the earlier systems. UMTS was not defined from scratch and reuses a lot of GSM. Long-Term Evolution (LTE) is a standard for high-speed wireless communication for mobile devices and data terminals, based on the GSM and UMTS technologies. It increases the capacity and speed using a different radio interface together with core network improvements. The standard is developed by the 3GPP (3rd Generation Partnership Project) and is specified in its Release 8 document series, with minor enhancements described in Release 9. LTE is the upgrade path for carriers with both GSM/UMTS networks and CDMA2000 networks. The different LTE frequencies and bands used in different countries mean that only multi-band phones are able to use LTE in all countries where it is supported. [10]
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Table 1 : Evolution Technologie
II.
Global System for Mobile Communications (GSM) II.1
Introduction
GSM, stands for Global Systems for Mobile Communications, is basic standard bearer of 2G technologies. It is mainly used in mobile communication. Short Messaging System (SMS) was introduced into GSM networks along with capability to download content from various service providers. The content could ring tone, logos and picture messages. It can support Voice telephony and data however the data rate is only 9.6Kb/s that is very low bit rate for date communication.
II.2
Architecture of GSM network
The GSM network have the primary role of enabling communications between GSM mobile subscribers and subscribers of the PSTN public switched telephone network. The GSM network interfaces with the PSTN network and includes switches, it’s distinguished by specific: radio access. GSM provides a means to distribute intelligence in the network. Network divided into four subsystems:
Mobile Station (MS). 27
Base station Subsystem (BSS): radio path control. Network Subsystem (NSS): call control. Operation Support Subsystem OSS: operation and maintenance
Figure 5: GSM Architecture
II.2.1 Mobile Station This Mobile station is a GSM mobile phone equipment which houses, RF chip and SIM (subscriber Identity Module). This SIM is enough to carry to avail the service of GSM network. SIM contains subscriber related all the information, network with which subscriber is subscribed with and encryption related information.
II.2.2 Base station Sub-System (BSS) Base station subsystem houses Base Transceiver station-BTS and Base station controllerBSC. This subsystem take care of radio control related functions and provides GSM air interface for GSM mobile phones to connect with GSM network. To provide GSM service, region/city on earth is divided into various cells. The cell size is usually about 100m to about 35 km. BTS coverage is limited to this cell. Like this many BTSs cover entire region. All this BTSs are interfaced with one BSC in various ways mesh, star etc. This BSC takes care of radio frequency assignments to the mobile phones, takes care of handoff within BSS i.e. between one BTS and the other BTS. 28
The BSS is constituted by:
Base transceiver station (BTS) Base Station controller (BSC)
II.2.3 Network Sub-System (NSS) The Network Switching Subsystem, called the Network Switching Center (NSS), plays a vital role in a mobile network. While the radio subnet manages radio access, the elements of the NSS support all the functions of control and analysis of information contained in databases required to establish connections using one or more of the functions: encryption, authentication or roaming. The NSS is constituted by:
Mobile Switching Center (MSC) Home Location Register (HLR) Authentication Center (AuC) Visitor Location Register (VLR) Equipment Identity Register (EIR)
MSC MSC
HLR
EIR
AuC
VLR Figure 6: The NSS structure
II.2.4 Operations Support System (OSS) The OMC or Operation and Maintenance Center is a basic element of a GSM or UMTS mobile network. Its role is to manage several BSCs and BTSs. It contains various information about the mobile network. The implementation of OMC is called the operation and support system (OSS). [13] The OMC allows the operator to know the weak points of his network, analyze and correct them. The process maintenance, with or without automation, is provided by back-office software components that interact with each other and are used in different services:
Provisioning The census Performance and Quality of service 29
Security management Inventory Installing and configuring network components Network error management Exploitation
II.3
Interfaces
The interfaces are used between the GSM network components for assure the traffic transmission and the signaling information. The table below describes the GSM interfaces and its utilizations. GSM Interfaces
Position
Utilization
Um
MS-BTS
Radio Interface.
Abis
BTS-BSC
The transmission of the Signaling Messages.
A
BSC-MSC
Mobility Management and call processing.
B
MSC-VLR
The information Transfer.
C
MSC-HLR
HLR interrogation for input call or short messages
D
VLR-HLR
Users’ information management and localization.
E
MSC-MSC
Short Messages transmission and Handover execution.
F
MSC-EIR
Verification of the terminal identity.
G
VLR-VLR
Users’ information management.
H
HLR-AUC
The data authentication exchange. Table 2 : The GSM Interfaces
II.4
Access methods
Multiple Access Technique allows many subscribers to use the same communication medium. In the GSM system there are two techniques, FDMA and TDMA. The most digital cellular systems use the technique of Time Division Multiple Access (TDMA) to transmit and receive speech signals.
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II.4.1 FDMA FDMA (Frequency Division Multiple Access) uses different frequency channels to accomplish communication. The whole frequency spectrum available is divided into many individual channels (for transmitting and receiving) and every channel can support the traffic for one subscriber or some control information.
II.4.2 TDMA
Figure 7: FDMA Access Method
TDMA accomplishes the communication in different timeslot. A carrier is divided into channels based on time. Different signals occupy different timeslots in certain sequence, that is, many signals are transmitted on the same frequency in different time. With TDMA, one carrier is used to carry a number of calls, each callusing that carrier at designated periods in time. These periods of time are referred to as timeslots. Each MS on Figure 8: TDMA Access Method a call is assigned one time slot on the uplink frequency and one on the downlink frequency. Information sent during onetime slot is called a burst. In GSM, a TDMA frame consists of 8 time slots. This means that a GSM radio carrier can carry 8 calls.
II.4.3 CDMA CDMA accomplishes the communication in different codes sequences. Special coding is adopted before transmission, then different information will lose nothing after being mixed and transmitted together on the same frequency and at the same time. Figure 9: CDMA Access Method
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II.5
The frequency spectrum
The GSM can work in a several bands, like GSM 850, GSM 900, DCS 1800 and PCS 1900.
GSM-900 and GSM-1800 are used in most parts of the world: Africa, Europe, Middle East, Asia (apart from Japan and South Korea where GSM has never been introduced) and Oceania. GSM-850 and GSM-1900 are used in most of North, South and Central America. In North America, GSM operates on the primary mobile communication bands 850 MHz and 1900 MHz. In Canada, GSM-1900 is the primary band used in urban areas with 850 as a backup, and GSM-850 being the primary rural band.
Table 3: GSM Standards
P-GSM, Standard or Primary GSM-900 Band. E-GSM, Extended GSM-900 Band (includes Standard GSM-900 band). R-GSM, Railways GSM-900 Band (includes Standard and Extended GSM900 band). There are two types of channels: The physical channel is the medium over which the information is carried. The logical channel consists of the information carried over the physical channels. A Physical Channel (a TS, defined by a fixed position (0-7) on a given TDMA frame) may be used to broadcast messages containing different kinds of information:
Traffic messages for speech and data, Signaling messages for different procedures and supplementary services, Synchronization messages for temporal and logical synchronization between the mobile stations and the BTS, Measurements messages for uplink report of the downlink measurements, Control messages: to manage the access to the network. 32
Figure 10: Channels types
We are particularly interested in two logical channels BCCH and TCH:
Broadcast control channel (BCCH): Generally, there is always a BCCH channel in every cell, which is responsible for broadcasting system information to the mobile station. These system information enable the MS to identify and access network at the idle mode. Traffic channel (TCH): when communication is established, a TCH channel is allocated and served to the transfer of speech or data.
II.6
GSM Handover
The process of handover or handoff within any cellular system is of great importance. It is a critical process and if performed incorrectly handover can result in the loss of the call. Dropped calls are particularly annoying to users and if the number of dropped calls rises, customer dissatisfaction increases and they are likely to change to another network. Accordingly GSM handover was an area to which particular attention was paid when developing the standard. Within the GSM system there are four types of handover that can be performed for GSM only systems [15] : 1) Intra-BTS handover: This form of GSM handover occurs if it is required to change the frequency or slot being used by a mobile because an interference, or other reasons. In this form of GSM handover, the mobile remains attached to the same base station transceiver, but changes the channel or slot. 2) Intra BSC handover: This form of GSM handover or GSM handoff occurs when the mobile moves out of the coverage area of one BTS but into another controlled by the same BSC. In this instance the BSC is able to perform the handover and it assigns a new channel and slot to the mobile, before releasing the old BTS from communicating with the mobile. 33
3) Intra MSC handover: When the mobile moves out of the range of cells controlled by one BSC, a more involved form of handover has to be performed, handing over not only from one BTS to another but one BSC to another. For this the handover is controlled by the MSC. 4) Inter-MSC handover: This form of handover occurs when changing between networks. The two MSCs involved negotiate to control the handover.
Figure 11: GSM Handovers
III.
Universal Mobile Telecommunications System (UMTS) III.1 Introduction
The introduction of 3G changed a lot of the accepted standards in the mobile phone industry. It allows the use of a greater bandwidth that allows more features to be implemented on it. 3G gives many features like video calls and TV applications because of the speed of 3G which began at 384kbps; well within DSL speeds. Further development on 3G technologies have also created even faster data rate reaching 3.6 and even 7.2Mbps. The existing GSM networks are not compatible with the 3G networks. To keep it, requires a new infrastructure. According to popularity and demand, Telecom Operators place 3G towers in those areas. They have to operate 2 radios in particular areas; one for GSM and one for 3G. Mobile phone Users are also required to switch mobile phones in order to take advantage of the new features of 3G.
III.2 Architecture of UMTS network The UMTS network architecture is divided into three main elements:
User equipment UE. Universal Terrestrial Radio Access Network (UTRAN) or Radio Network System (RNS). 34
Core Network (CN)
Figure 12: UMTS Architecture
III.2.1
User Equipment (UE)
The User Equipment or UE is the name given to what was previous termed the mobile, or cellphone. The new name was chosen because the considerably greater functionality that the UE could have. It could also be anything between a mobile phone used for talking to a data terminal attached to a computer with no voice capability.
III.2.2
Radio Network Subsystem (RNS)
The RNS also known as the UMTS Radio Access Network, UTRAN, is the equivalent of the previous Base Station Subsystem or BSS in GSM. It provides and manages the air interface for the overall network. It’s comprises two main components:
Radio Network Controller, RNC: This element of the UTRAN controls the Node B that are connected to it, i.e. the radio resources in its domain. The RNC undertakes the radio resource management and some of the mobility management functions, although not all. It is also the point at which the data encryption / decryption is performed to protect the user data from eavesdropping.
Node B: Node B is the term used within UMTS to denote the base station transceiver. This part of the UTRAN contains the transmitter and receiver to communicate with the UEs within the cell. It participates with the RNC in the resource management. NodeB is the 3GPP term for base station, and often the terms are used interchangeably.
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III.2.3
Core Network
The core network provides all the central processing and management for the system. It is the equivalent of the GSM Network Switching Subsystem or NSS. The UMTS core network architecture is a migration of that used for GSM with further elements overlaid to enable the additional functionality demanded by UMTS. In view of the different ways in which data may be carried, the UMTS core network split into two different areas:
Core Network
CS
MSC
PS
GMSC
SGSN
GGSN
Figure 13: Core Network Components
Circuit switched elements (CS): These elements are primarily based on the GSM network entities and carry data in a circuit switched manner, i.e. a permanent channel for the duration of the call. The CS include: Mobile switching center (MSC): This is essentially the same as that within GSM, and it manages the circuit switched calls under way. Gateway MSC (GMSC): This is effectively the interface to the external networks. Packet switched elements (PS): These network entities are designed to carry packet data. This enables much higher network usage as the capacity can be shared and data is carried as packets which are routed according to their destination. The PC include: Serving GPRS Support Node (SGSN): As the name implies, this entity was first developed when GPRS was introduced, and its use has been carried over into the UMTS network architecture. Gateway GPRS Support Node (GGSN): Like the SGSN, this entity was also first introduced into the GPRS network. The Gateway GPRS Support Node (GGSN) is the central element within the UMTS packet switched network. It handles inter-working between the UMTS 36
packet switched network and external packet switched networks, and can be considered as a very sophisticated router. In operation, when the GGSN receives data addressed to a specific user, it checks if the user is active and then forwards the data to the SGSN serving the particular UE. Shared elements The shared elements of the 3G UMTS core network architecture include the following network entities:
Home location register (HLR): This database contains all the administrative information about each subscriber along with their last known location. In this way, the UMTS network is able to route calls to the relevant RNC / Node B. When a user switches on their UE, it registers with the network and from this it is possible to determine which Node B it communicates with so that incoming calls can be routed appropriately. Even when the UE is not active (but switched on) it re-registers periodically to ensure that the network (HLR) is aware of its latest position with their current or last known location on the network.
Equipment identity register (EIR): The EIR is the entity that decides whether a given UE equipment may be allowed onto the network. Each UE equipment has a number known as the International Mobile Equipment Identity. This number, as mentioned above, is installed in the equipment and is checked by the network during registration.
Authentication center (AuC): The AuC is a protected database that contains the secret key also contained in the user's USIM card.
III.3 Interfaces The most important interfaces of UMTS is: UTRAN
Position
Utilization
Uu
UE - NodeB
Communication with UTRAN
lub
NodeB - RNC
lur
RNC - RNC
Inter-RNC communication.
lu-CS
RNC – MSC/VLR
Connects the radio network to the circuit switched core network
lu-PS
RNC – SGSN
Interfaces
lu
Interface allowing communication between the Node B and the RNC.
Connects the radio network to the packet core network that comprises the SGSN and GGSN. Table 4: UMTS Interfaces
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III.4 Access methods III.4.1 WCDMA The choice of WCDMA (Wideband Code Division Multiple Access) for use with the third generation, 3G UMTS telecommunications system arose from a variety of technical reasons. It offers significant advantages over the schemes used in the previous 2G systems that were predominantly TDMA based schemes. The main benefits of the use of WCDMA as a multiple access scheme are:
Improved spectral efficiency: The use of WCDMA as the multiple access technology, combined with the QPSK modulation format used provides significant improvements in terms of the spectral efficiency. Figures for the performance improvements gained vary considerably dependent upon the conditions, but the scheme gives some significant benefits. Some calculated estimates give figures as high as three or four times that of technologies such as GSM, although in reality the benefits may be a bit less.
Adjacent cells may use the same channel frequency: As a result of the way in which spread spectrum signals such as WCDMA operate.
Improved handover: Within WCDMA it is possible to do what is termed a "soft handover" where the UE communicates with two base stations at the same time. This significantly improves handover reliability.
Enhanced security: The use of spread spectrum and the multiple spreading codes for WCDMA significantly reduces the possibility of eavesdropping, although within GSM eavesdropping of the transmitted signal was not the problem it was for the original analogue systems where anyone with a scanner radio receiver could listen to telephone conversations.
The basic difference between the CDMA and WCDMA is bandwidth, CDMA uses 1.25 MHz frequency bandwidth while WCDMA uses 5 MHz bandwidth. Also CDMA is 2G telecommunication standard and provide very less data rates compared to WCDMA which is third generation technology. CDMA being 2g standard provide mainly circuit switched services while WCDMA being used in UMTS system is used in both circuit switched and packet switched networks.
III.5 The frequency spectrum The important bands used by UMTS are:
UMTS 2100: (IMT-2000) International Mobile Telecommunications for the year 2000. It used in Europe, Asia, Oceania and Africa.
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UMTS 1900: (PCS) Personal Communications Service (PCS). It used in the USA and Canada. UMTS 1800: (DCS) Digital Communication System. It used in Japan. UMTS 900: (E-GSM) it used in Europe, Asia, South Africa and Australia. UMTS 850: it used in the USA, Canada and Australia. UMTS 800: It used in Japan only.
III.6 UMTS Handover Handover or handoff is as important for UMTS as any other form of cellular telecommunications system. As with any other cellular telecommunications system it is essential that UMTS handover is performed seamlessly so that the user is not aware of any change. Any failures within the UMTS handover procedure will lead to dropped calls which will in turn result in user dissatisfaction and ultimately it may lead to users changing networks, thereby increasing the churn rate. [12]
Soft handover: This form of handover is a more gradual and the UE communicates simultaneously with more than one Node B or base station during the handover process.
Figure 14: Soft Handover
Softer handover: Not a full form of UMTS handover, but the UE communicates with more than one sector managed by the same NodeB.
Figure 15: Softer Handover
Hard handover: This form of handover is essentially the same as that used for 2G networks where one link is broken and another established. The MS is linked to no more than one BTS at any given time. Figure 16: Hard Handover
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IV.
Advantages and disadvantages of 2G and 3G
2G/3G (GSM/ UMTS) network have many advantages and disadvantages, the most important and needed in the next chapter are:
Coverage Penetration Capacity Interferences Debit
GSM + large coverage + excellent penetration - not enough capacity - much problems in the air interface - low data rate
UMTS - low coverage - the penetration loss is more than GSM + more capacity + most interfaces problems are fixed + high data rate
Table 5: Advantages and Desadvantages of 2G/3G
At recent years, the 2G users are migrating to 3G technology because the variety of services offer by this technology. In other side, the mobile data traffic is increasing rapidly in the 3G network and saturation of the 2100 band is presented that will cause a problem in the future if we not find a solution. Cause that the 3GPP found a solution for this problem named “UMTS900”. This solution will be the principal term in our project.
V.
BTS 3900 V.1
Definition
A Base Transceiver Station (BTS) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UEs are devices like mobile phones or computers with wireless Internet connectivity. The network can be that of any of the wireless communication technologies like GSM, CDMA, Wi-Fi, WiMAX or other wide area network (WAN) technology. The BTS3900 developed by Huawei is an indoor macro BTS. The BTS3900 mainly consists of the BBU and RFU. Compared with traditional BTSs, the BTS3900 features simpler structure and higher integration.
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Figure 17: BTS Structure
V.2
BTS location
Figure 18: BTS location
V.3
BTS 3900 Hardware components
Abbreviation
41
Broad band/Models
Full Name
BSBC
Universal BBU Sub-rack Backplane type C (2U)
UEIU
Universal Environment Interface Unit
GTMU
GSM Transmission and Management Unit for the BBU
UELP
Universal E1/T1 Lightning Protection Unit
UBFA
Universal BBU Fan unit type A (2U)
UPEU
Universal Power and Environment interface Unit
DRFU
Double Radio Filter Unit
DCDU-01
Direct Current Distribution Unit
GATM
GSM Antenna and TMA Control Module
PMU
Power and Environment Monitoring Unit
PSU (AC/DC)
Power Supply Unit (AC/DC)
PSU (DC/DC)
Power Supply Unit (DC/DC)
FAN Box
FAN Box Table 6: BTS Abreviations
Hardware Structure of the BTS3900 (48V) The BTS3900 cabinet (-48V) uses the external 48V DC input. The DC power is directly led into the DCDU-01 and the DCDU-01 distributes the DC power to each component in the cabinet. The BTS3900 cabinet (-48V) consists of the following components: the MRFUs, BBU, DCDU01, and FAN unit. You can optionally install devices of 3U in height in the spare space of the cabinet. The figure above show the fully configured cabinet (-48V):
Figure 19: BTS3900 Hardware Structure (-48V)
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V.3.1 BBU3900 V.3.1.1 BBU3900 Equipment The typical power consumption of the BBU is 50 W. The BBU3900 is a small box with all the external ports on the front panel, it can be installed in a 19-inch-wide and 2U-high indoor space or outdoor protective cabinet.
Figure 20: BBU3900 Components
V.3.1.2 BBU3900 Functions As the baseband processing unit, the BBU3900 provides ports for connection between the dual mode base station and the BSC/RNC and between the BBU3900 and the RF modules. The BBU3900 has the following functions:
Provides ports for communication between the base station and the BSC/RNC. Provides CPRI ports for communication between the BBU and the RF modules. Provides USB ports, facilitating the automatic software upgrade of the dual-mode base station when a USB disk is inserted during software installation and data configuration. Processes uplink and downlink data. Manages the entire dual-mode system in terms of OM and signaling processing. Provides the system clock. V.3.1.3 BBU3900 Slots The slots of the BBU3900 GSM, BBU3900 GU, and BBU3900 UMTS are the same.
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Figure 21: BBU3900 Slots
V.3.1.4 BBU Cables
Figure 22: BBU Cables
GTMU Board The GSM Transmission, Timing, and Management Unit for BBU (GTMU) controls and manages the entire BTS in GSM mode. It provides interfaces related to the reference clock, power monitoring, OM, and external alarm collection. It has a following functions:
Controlling, maintaining, and operating the BTS. Providing fault management, configuration management, performance management, and security management. Monitoring the fan module and the power supply module. Providing four routes of E1 transmission. Providing CPRI ports for the communication with the RF modules. Distributing and managing BTS clock signals. Providing the Ethernet port for local maintenance. Providing clock output for testing.
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Figure 23: GTMU Board
WMPT Board This describes the WCDMA Main Processing and Transmission unit (WMPT). It is the BBU3900 main control and transmission board that processes the signals and manages the resources for other boards. The WMPT has the following functions:
Providing Operation and Maintenance (OM) functions such as configuration management, equipment management, performance monitoring, signaling processing, and active/standby switchover and providing OM channels connected to the OMC (LMT or M2000). Providing the reference clock. Processing signaling and managing resources for other boards in the BBU. Providing USB ports, one of which facilitates automatic base station upgraded when a USB disk is inserted during software installation and data configuration. Providing four E1s/T1s which support ATM and IP protocols.
Figure 24: WMPT Board
WBBP Board This describes the WCDMA Baseband Process Unit (WBBP) board. It is a mandatory board of the BBU3900 that processes baseband signals. The WBBP has the following functions:
Provides the CPRI ports for communication between the BBU and the RFU, and supporting CPRI ports in 1+1 backup mode. Processes uplink and downlink baseband signals.
Figure 25: WBBP Board
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UPEU Board This describes the Universal Power and Environment Interface Unit (UPEU) board. It is a mandatory board of the BBU3900 that converts -48 V or +24 V DC to +12 V DC. The UPEU has the following functions:
Converting -48 V or +24 V DC to +12 V DC that is applicable to the boards. Providing two ports with each transmitting one RS485 signal and another two ports with each transmitting four dry contact signals. Providing reverse connection protection for power cable connectors. The UPEU is classified into the Universal Power and Environment Interface Unit “Type A” (UPEA) and the Universal Power and Environment Interface Unit “Type B” (UPEB). The UPEA converts -48 V DC to +12 V DC and the UPEB converts +24 V DC to +12 V DC.
Figure 26: UPEU Board
V.3.2 MRFU Module The MRFU is a multi-carrier RF filtering unit. One MRFU supports a maximum of 6 carriers in GSM mode, 4 carriers in UMTS mode and 6 carriers in GSM + UMTS mode. Functions:
Implements the direct frequency conversion technique in the transmit channel, modulates the baseband signals to GSM RF signals; then, sends the signals to the antenna for transmission through the duplex filter after filtering, amplifying, and combining the RF signals. The combining can be performed as required. Receives RF signals from the antenna and performs down-conversion, amplification, analog-to-digital conversion, digital down-conversion, matched filtering. Provides power sharing. Improves the network coverage, reduces the interference and power consumption and save the device cost. Provides power control, reverse power detection. Provides frequency synthesis and loopback test. Generates the CPRI clock, recovers the CPRI clock of lost synchronization, and detects alarms. Provides the function of DPD/BPD.
V.3.3 DUDC Module The direction current distribution unit (DCDU) provides -48V DC power of 10 outputs. The functions of the DCDU are: 46
Receiving -48 V DC power input. Distributing the -48 V DC power of 10 outputs for boards and modules in the cabinet. Providing surge protection of 10 kA in differential mode and 15 kA in common mode and providing dry contact for surge protection failure.
Figure 27: DUDC Module
V.3.4 FAN Box The fan box regulates the temperature at the air inlet of the cabinet and in the fan box. It can adjust the rotation speed of the fans to implement ventilation and dissipation for the cabinet. The fan box performs the following functions:
Provides forced ventilation and dissipation for the cabinet. Supports two modes of adjusting the rotation speed of the fans: adjustment based on the temperature and adjustment controlled by the central processing unit. Detects the temperature. Communicates with the central processing unit to report alarms and the adjusted rotation speed of the fans based on the temperature to the central processing unit. Stops the rotation of the fans when the ambient temperature is low.
Figure 28: FAN Box
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VI.
Conclusion
We have seen in this chapter a brief introduction about the technological evolution from 1G to LTE, some general notions about GSM and UMTS networks and especially its architectures. Also we have seen the BTS3900 components and its functions. The whole of these notions is important to understand the next chapter where we will explain the process of U900.
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Chapter 3: U900 Deployment
This chapter give an overview about deployment of U900, and describe GU900 reframing, and deals with the migration strategy from GSM to UMTS 900.
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I.
Presentation of the U900 Technology?
The 900 MHz frequency band has historically been used to provide second generation mobile services using GSM technology, and because of the limitation of the 2100MHz spectrum band and the growing number of UMTS customers, the mobile telecommunications community is potentially seeking to pass the GSM900 MHz band for UMTS. UMTS900 has a number of advantages and benefits over 3G in the 2100 MHz band such as better coverage in urban and rural areas, improved penetration and indoor coverage, low deployment and maintenance costs, which will be explained in this section. Besides this it is a highly cost-effective solution for providing UMTS services in both urban and rural areas. The deployment of UMTS over the 900 MHz band is possible by reducing the available spectrum for the GSM band, which needs to be carefully planned. Frequency re-farming strategy, interference analysis and traffic migration remain the main planning challenges. The re-allocation strategy for the existing 900 MHz spectrum should be designed to reduce interference between GSM and UMTS through the use of separation requirements. The traffic migration strategy for GSM900 users towards the 1800 MHz band in order to lighten the load on the GSM900 band. Deployment is a strategy where telecom operators reuse their frequency resources to introduce new radio communication technologies to improve the spectral efficiency and data throughput. As users’ demand increases on data services, GSM is not sufficient to satisfy the users’ data need. For example, the mainstream 900 MHz deployment and re-farming solution is that operators free about 5MHz of the GSM on the 900 MHz band and deploy UMTS on the 900 MHz frequency band. In the nutshell, in this chapter we will first look at the introduction of UMTS900 technology, the benefits and challenges of U900 and then we will introduce the concept of re-farming before studying the different scenarios of possible deployment of the solution and analyze the different types of significant interference related to this re-farming. To close this chapter, we will explain the general processes of the deployment of the U900, the planning and optimization. [8]
II.
U900 Solution II.1
Why Choosing U900?
The 900MHz frequency band is primarily being used for GSM services, although, while it is currently being used to bear GSM services, it is also being considered for UMTS service bearing by carriers and vendors for the following reasons. The need for reducing costs. Normally, the higher the frequency band, the smaller the coverage, therefore, the coverage of 900MHz is greater than that of 2100MHz. In fact, there is actual test data that backs this up. For service coverage in the same area such as, CS64K service, 50
UMTS2100M is used, with 224 stations; while for UMTS900, 90 stations are used. In this case, stations used in 900MHz represent only 40% of those used for 2100MHz, hence, saving 60% in terms of station resources. As for PS service, it also uses far fewer stations and costs less for 900MHz than for 2100MHz. Moreover, according to a recent estimate made by an operator in Europe after construction of its UMTS900 pilot network, it will cost approximately USD 8 million to build a UMTS network, using 2100MHz, in three years, but it will only cost about USD 5 million to construction a 900MHz, thus, saving approximately 37% in terms of CAPEX. The need for network expansion. Some networks have used 2100MHz as a reference frequency, but with the continuous increase of network subscribers and a switch in consumption practice to data services, this type of frequency is unable to meet the needs for capacity expansion. Under such circumstances, the problem of inadequate capacity can be solved by introducing a new frequency band such as 900MHz, which is able to share part of the capacity. [2] Individual carriers are not licensed with 2100MHz frequency, but own idle resources in 900MHz. Such carriers have not obtained the 2100MHz frequency band from the appropriate authorities, who are in charge of allocating frequency bands in different countries, due to historical reasons, or other reasons, so instead, they have turned to using the GSM900 frequency which they already own when preparing to build UMTS networks. In nutshell UMTS900 can complement 2100 MHz deployments to improve coverage, reduce CAPEX and OPEX, improve quality of service and enhance the user experience. UMTS900 operators can provide HSPA over much larger areas in a very cost-efficient way. GSM operators can also re-use many existing network assets e.g. antennas, network management systems when they migrate to UMTS900. [1]
II.2
Advantages of U900
Improved Spectral Efficiency: The 900 MHz devices are most commonly used. Industry statistics show that the most smartphones in the market work in 900MHz.
Gains in coverage: UMTS900 has a 7 dB path loss advantage over UMTS2100 in free space conditions. This advantage can be more than 20 dB in indoor scenarios, as a result, the deployment of UMTS900 saves equipment cost by reducing the number of sites in suburban areas and provides a better and deeper indoor coverage in urban areas.
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Figure 29: frequency band allocation and technology deployment for the operator
Improved urban indoor coverage
Less transmission and penetration loss than U2100 Better for indoor coverage and has better network
coverage performance
Gains in capacity: UMTS900 has larger throughput and capacity than UMTS2100 since UMTS900 has higher receive levels and Ec/Io.
Improved network QoS and better user experience.
Saving CAPEX and OPEX costs
Figure 30: impact of UMTS 900
The ability to use the infrastructure to existing GSM 900 networks 52
Deployed rapidly UMTS900 (co-site), reused cabinets, hardware, power, backup system, antenna, transmission
Figure 31: Coverage against the same power of emission and the indoor coverage
II.3
Key Problems Concerned With U900 and Their Solutions
During the construction of UMTS900 networks, carriers may encounter a few problems that are listed as below, along with solutions that are specifically tailored for such problems:
II.3.1 Mutual effect on networks The places where UMTS900 is being deployed are currently covered by UMTS2100 and GSM900 networks. The introduction of UMTS900 will occupy part of the existing GSM900 frequency, which will lead to a degradation of the call quality of GSM subscribers and also cause an increase of call drops if no reasonable frequency allocation is made. Furthermore, the existing GSM network will cause a decline of network KPI on the newly introduced UMTS900 network. In consideration of this problem, Huawei has conducted in-depth technological analysis on the same-frequency networking of UMTS900 and GSM900 in its UMTS900 solution, and has designed an advanced frequency re-farming solution, with optimization of the performance of UMTS stations. THIS SOLUTION offers two benefits: first, the frequency intervals between two adjacent UMTS and GSM carriers can be smaller than what is required in the protocol, thus, significantly increasing the utilization of frequency; and second, UMTS stations are enhanced against interference from GSM near ends, hence, avoiding a decline of network KPI, which is caused to a great extent by the introduction of UMTS900 and interference from GSM and UMTS. Moreover, Huawei's UMTS900 is capable of completely reusing the existing GSM900 infrastructure so that it is able to share stations, the antenna feeder and transmission. This not only saves in terms of network construction costs and the speed of deployment of the network, but also saves in regards to the rental expenses of iron towers in certain regions.
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The above-mentioned technologies have been successfully verified. Moreover, the network quality of carriers is guaranteed, and a great amount of costs are also saved.
II.3.2 Interoperability between U900 and existing network So far, interoperability between UMTS2100 and GSM900 has been achieved, which allows subscribers to roam and switch over and choose between many services which are offered on both networks. After the introduction of UMTS900, problems will arise, which, if not handled properly, will surely affect the use of the UMTS900 network by subscribers. For such problems, standards have been formulated to ensure interoperability between networks. In addition, Huawei has carried out interoperation and interworking between the core networks and station equipment on both 2G and 3G commercial networks in the pilot networks, for multiple vendors in Europe. Huawei worked together with Maroc Telecom to successfully complete calls on its UMTS900 commercial network by interoperation, and was able to deliver UMTS900-based HSDPA 3.6Mbps service. The test results show that the UMTS900 network interworks perfectly with Maroc Telecom's commercialized UMTS/GSM networks, and in particular, the services running on both UMTS900 and GSM900 proved to be both stable and reliable, without any noticeable interference, and subscribers were able to easily switch over between the two networks. [9]
II.4 Re-farming II.4.1 What is Re-farming? Re-farming is a strategy that telecom operators reuse their frequency resources and introduce new radio communication technologies to improve the spectral efficiency and data throughput. For example, the mainstream GU 900 MHz Re-farming solution is that operators free about 5 MHz of the GSM on the 900 MHz band and deploy UMTS on the 900 MHz frequency band. Generally, the recommendations for our project being the UMTS900 re-farming state the release of 4.2 MHz of the 900 MHz band of GSM (we will show in the following that the width of this portion of band can vary from 4.2 MHz to 5 MHz according to the deployment strategy adopted). [2]
II.4.2 Challenges of the GU 900 MHz Re-farming The deployment of U900 MHz also brings challenges to network planning and may affect network performance. The following are operators' concerns about implementing the U900 MHz deployment:
How to reduce co-channel and adjacent-channel interference between GSM900 and UMTS900 networks. 54
After the Re-farming, the GSM frequency resources are greatly reduced. In this case, how to smoothly transfer GSM900 traffic to the GSM1800 or UMTS900 network to keep the GSM network quality.
Whether the antenna of the GSM900 network can be reused by the UMTS900 network with network quality kept and cost saved.
How to balance traffic load among the GSM and UMTS networks after the UMTS900 deployment.
The preceding questions are of great concerns to the operators and are the key to the success of the U900 MHz Deployment solution.
II.5
Frequency Allocation between GSM and UMTS Networks
GSM900 and UMTS900 interference for the same operator as well as the UMTS900 interference from Maroc Telecom and the GSM900 network from another operator with an adjacent band are the main criteria for distinguishing between these types of frequency allocation. Consequently, the choice of the solution to be adopted will depend on the distribution of the frequency spectrum allocated to the three national operators as well as the width of the Maroc Telecom GSM frequency band. There are two re-farming solutions that can be used to deploy the UMTS900 network:
II.5.1 Edge Frequency Allocation Mode
Figure 32: Edge frequency allocation mode
The UMTS and the GSM are arranged side by side on the relevant frequency band, and UMTS and GSM allocated side by side. The center frequency separation (f 1) between the UMTS and the GSM of the same operator can be configured to the minimum spacing. [1] The center frequency separation (f 2) between the UMTS and the GSM of other operators should be 2.6 MHz at least for the following reason: 55
If the adjacent frequency separation between the UMTS and the GSM of another operator is lower than 2.6 MHz, the UTMS bandwidth is 4.2 MHz and but the terminal still uses a bandwidth of 5 MHz; consequently, the frequency resources of another operator are occupied.
Advantages If the edge frequency allocation mode is adopted, the center frequency separation between the UMTS and the GSM of the same operator and between the UMTS and the GSM of other operators should be considered. Because of the continuous spectrum of GSM, Re-farming will not increase complexity for frequency re-planning. And there's no change requirement when UMTS enlarge to the second carrier in future [5].
Disadvantages If the edge frequency allocation mode is adopted, the interference between the new UMTS and the adjacent GSM of other operators must be considered. In GU co-located sites, it is relatively easy to analyze and adjust the interference between the UMTS and the GSM. The interference between the UMTS and the GSM of other operators, however, must be considered according to the worst scenario. If the adjacent frequency is used by a CDMA system of another operator, the UMTS located at the edge, compared with the GSM at the edge, suffers severer interference from the CDMA system. For example, the blocking requirement of the GSM is –16 dBm, while that of the WCDMA system is –47 dBm. To resist the interference from the CDMA system, the system isolation is required to be improved by a higher filter suppression value or adjusted engineering parameters of the UMTS.
II.5.2 Sandwich Frequency Allocation Mode [Recommended By Huawei]
Figure 33: Sandwich frequency allocation mode
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Inside the frequency band of an operator, the UMTS is arranged in the middle and the GSM is arranged at both sides. If the center frequency separation f1 or f2 is smaller than 2.6 MHz, the GSM and the UMTS can share the frequency resources with low power density at both sides of the UMTS. In this way, the number of additional GSM carriers is twice that in the edge frequency allocation mode. In the sandwich allocation mode, the UMTS carrier can be arranged at any location (unnecessarily at the center) in the spectrum resources of the operator, depending on the operator's strategies. For later capacity expansion of the UMTS, the operator may allocate more frequencies to support two UMTS carriers. To avoid adjusting the previous UMTS frequency, asymmetric frequency allocation can be adopted to make one side of the UMTS carrier near either edge of the spectrum. In this way, the continuous GSM spectrum at the other side is larger than 5 MHz, which facilitates expansion to the second UMTS carrier. [7]
Advantages For an operator, if the sandwich frequency allocation mode is adopted, the UMTS frequencies are allocated inside its own frequency resource without interference to the GSM or other systems of other operators on the adjacent frequency bands. If the reserved buffer zone is configured according to the specific requirements, normal operation of both systems is ensured.
Disadvantages If the sandwich frequency allocation mode is adopted, both the center frequency of the UMTS and the GSM frequencies must be adjusted during the later capacity expansion of the UMTS. The available GSM frequency band consisting of the remaining frequencies is not continuous, which causes difficulties for radio planning of GSM frequencies. Allocation
Advantages - No Interference problem need to be reconsidered for the UMTS900 and other operator’s system.
Disadvantages Discontinuous frequencies make GSM frequency planning more complicated.
Sandwich
-Save more GSM frequencies while using a non-standard separation.
Edge
- Facilitate GSM frequency planning Frequency gap f2 of 2.2 MHz must and expanding to second UMTS. be reserved between the UMTS carrier and the adjacent GSM carrier - Only one side of GU interference of the other operator needs be considered. Table 7: A comparative table between the two modes
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Recommended GU Frequency Allocation The sandwich frequency allocation mode is preferred for 1:1 GU co-located site scenarios according to the comparison between the two frequency allocations modes and the interference data in the case of nonstandard GU separation. The sandwich frequency allocation mode results in severer inter-system interference, but the impact caused by the interference on the network performance is acceptable in 1:1 GU colocated site scenarios due to the improved RF counters of Huawei SRAN. In UMTS 900MHz network, the bandwidth may be less than 5MHz because of smaller frequency resource from GSM network. Thus, non-standard frequency separation is adopted. And UMTS 4.2MHz is the recommended solution for both UMTS network deployment feasibility and the benefit to GSM. When using UMTS non-standard bandwidth 4.2MHz, 4 frequency channels can be saved for GSM correspondingly. The sandwich allocation method is the preferred solution if 4.2 MHz is allocated for UMTS. For better 2G quality, it’s suggested to use 4.2M for U900, because only 6% less than standard 5.0M, and 4 GSM frequencies can be saved for GSM
Figure 34: UMTS non-standard separation configuration
MAROC TELECOM Frequency Band Plan Radio frequencies are exceptional resources. Rapid expansion, including mobile communications services, makes radio spectrum management more difficult. Each operator has a number of carriers for the bands he uses to deploy his network. Maroc Telecom has 63 carriers for the 900 MHz band (range 16-> 79), and 48 carriers for the 1800 MHz band (range 512-> 560). The allocations proposed by Huawei Technologies, for the UMTS spectrum in the 900 band:
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Specter 5 MHz in Edge mode: The width of a UMTS carrier
Specter 4.2 MHz in Sandwich mode: Actually we use only 3.84MHz of this band so a band of 4.2 MHz will be largely sufficient, without resorting to guard frequencies.
Figure 35: Frequency distribution
Finally Maroc Telecom's choice was as follows: "Spectrum 4.2 in Sandwich Mode". (Other details are confidential).
II.6
Deployment Scenarios
Better propagation and in-building coverage make UMTS900 deployments attractive in rural, suburban, and urban morphologies. Initial deployments are expected to be in rural areas mainly to increase the UMTS footprint with less cost. Urban deployments will follow later to provide better in-building coverage and to fill in coverage holes in the UMTS2100 network with optimized inter-frequency (inter-band) handovers and reselections. UMTS900 can also be used to share the load of UMTS2100 network. The deployment of the U900 solution can be divided into three scenarios
II.6.1 Scenario 1 [Extend 3G Coverage in Sub-urban & Rural] In the urban areas or densely populated towns, consecutive UMTS 2100 network is constructed. In the suburb areas or rural areas, expand the UMTS coverage through the U900. On this scenario, re-farming should be deploying step by step usually, buffer zone planning is needed. Because the traffic in urban is higher, interference should be noticed when planning buffer zone on the board between urban and suburb. In additional, because of the high base station 59
existing in the Sub-urban or Rural area, the interference range should be control during the refarming process.
Figure 36: Extend 3G Coverage
II.6.2 Scenario 2 [Improve 3G Coverage in Urban area] Improved 3G coverage of urban areas that extend the indoor coverage. For this scenario the handover is frequent between UMTS2100MHz and UMTS900MHz because of the difference in quality of coverage. If the re-farming deploy on the dense urban area first, because the more same frequency protected sites need to clear out, it is senseless to plan buffer zone. Huawei suggest re-farming in whole area and not plan buffer zone in urban area
Figure 37: Improve 3G Coverage
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II.6.3 Scenario 3 [Initial 3G Roll-out In All areas] Proposes to set up UMTS900 in areas not with no 3G coverage, since the 900MHz spectrum is enough to re-farm the entire network. There is no co-channel interference on this scenario and buffer zone planning is not needed. The spectrum which deploys U900 can be clean out one time to redesign frequency.
Figure 38: Initial 3G Roll-out
Deployment objectives of UMTS900 vary for rural and urban morphologies. The main objective in rural deployments is to augment coverage and improve 3G footprint. In urban deployments, objectives are multiple: improve in-building coverage, fill in UMTS2100 coverage holes, and load sharing. [6]
Figure 39: Extend 3G Coverage
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III.
Interferences analysis
Interferences analysis is the major challenge posed by the deployment of the UMTS 900 network remains the reduction of co-channel and adjacent channel interference especially between the UMTS900 and the GSM900. Since the frequency band allocated to the UMTS is taken from the frequency spectrum dedicated to the GSM network, the WCDMA signals of the UMTS900 network and the GSM 900 signals have very similar or even quasi-similar frequencies. Interference between these two signal ranges is therefore at the center of operators' concerns because they could seriously affect the quality of communications.
Figure 40: What and where the potential problems are
III.1 Types of interferences Both the GSM and the UMTS are deployed on the 900 MHz frequency band. The GSM uplink is close to the UMTS uplink, and the GSM downlink is also close to the UMTS downlink. The interference analysis focuses on the interference between BSs and terminals. As shown in the figure below, the interference between the GSM and the UMTS for 900 MHz Re-farming is classified into four types according to interfered and interfering objects.
Interference caused by the GSM BTS to the downlink of the UMTS UE
Interference caused by the GSM MS to the uplink of the UMTS NodeB
Interference caused by the UMTS NodeB to the downlink of the GSM MS 62
Interference caused by the UMTS UE to the uplink of the GSM BTS
Figure 41: Types of interference between GSM and UMTS
The green arrows indicate wanted signals and the red arrows indicate interfering signals. In the case of SRAN networking, the GSM BTSs are generally co-located with the UMTS NodeBs. They are separated in the figure only.
III.2 Interference reduction III.2.1 Minimization of carrier separation interferences This solution minimizes interference caused by adjacent carriers between GSM900 and UMTS900.
Figure 42: Minimization of carrier separation interferences
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This is done in such a way that the two adjacent frequencies of the sandwich solution should not be assigned to the same cell, they will be assigned to different cells. The figure below shows the process of separating adjacent carriers.
III.2.2 Solution
Minimize interference by scheduling buffer zones
After re-farming, GSM frequency resources are significantly reduced to deploy U900. If the re-farming is implemented not in entire network, it will bring co-channel interference between re-farmed area and un-re-farmed area, and it cannot be eliminated through filtering. Thus, during re-farming, buffer zones need to be temporary defined to isolate the interference between U900 and G900. Buffer zone planning means maintain a guard band through geographic isolation to limited and mitigating co-channel interference, and reduce the risk of radio Network performance degradation after re-farming. The interferences that shall be considered by coverage prediction for buffer zones planning are listed as below:
Interference generated by U900 NodeB to G900 MS
Interference generated by U900 UE to G900 BTS
Interference generated by G900 BTS to U900 UE
Interference generated by G900 MS to UMTS NodeB
The buffer zone will be planned based on GSM site which have been impact on the same frequency through joint coverage prediction between GSM and UMTS. This method is applied to the early period of buffer zone planning. In the case of GSM and UMTS co-channel interference, a space separation is required to reduce the co-channel interference. Areas with UMTS networks deployed and their peripheral areas form a band-type area. In this area, GSM networks cannot use frequencies overlapped in UMTS frequency spectrums and therefore GSM network capacity decreases. A large space separation for co- Figure 43: Buffer Zone Design Process channel interference decreases impacts of GSM and UMTS co-channel interference on network performance. For space separation for co-channel interference, buffer zone planning solution is based on emulation and onsite traffic statistics to accommodate different scenarios. Huawei's proposed Buffer Zone solution, solves the problem of interference when the UMTS900 and GSM900 sites use the same frequency. After re-farming, the UMTS network occupies a frequency band already used by the GSM network. However, these frequencies are still 64
used by the GSM network outside the re-farming zone. Meanwhile, co-channel interference appears between GSM and UMTS since they use the same frequencies. To minimize this interference, a buffer zone must be scheduled.
Figure 44: Location of the Buffer Zone
Some frequencies used by the UMTS network in the Re-farming area are still used by the GSM network outside the Re-farming area. As a result, co-channel interference between the GSM and UMTS network may occur at the Re-farming area edge. A buffer zone can be established to reduce such interference. As shown in figure below, the same frequency can be used in Area A (GSM900 & UMTS2100) and Area C while frequencies used in Area A cannot be used in Area B, which is called the buffer zone. [4]
III.2.3
Summary
The preferred scenario is to use coordinated GSM and U900 sites and the U900 carrier sandwiched in-between GSM carriers. The closest/overlapping GSM carriers should be TCH only (not a BCCH carrier), having the smallest traffic load possible and aggressive power control. This setup allows the use of a carrier spacing as low as 2.2MHz with low performance degradation both on WCDMA and GSM.
Figure 45: frequency allocations
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IV.
Traffic Migration
Rather than deciding how much spectrum to leave, the question should be how efficiently used is the GSM spectrum today. Spectrum re-farming can be performed in steps and will continue as traffic begins to migrate to the newer technologies. One of the first considerations for re-farming is to determine the spectral efficiency of a GSM network considering current traffic load. Many networks have been built over several years and are far from optimal. Using global operator benchmarking, a network can be easily assessed to determine The potential for re-farming. Typically, most operators have some room for either or both HSPA 900. One of the most important aspects of improving spectrum efficiency is to ensure that the fundamental cell plan is as optimal as possible through correct site locations, parameter settings and antenna positioning. Once these are in place, further efficiency improvements can be achieved through advanced software along with further parameter optimization. [5]
IV.1 Release of 5 MHz from the 900 MHz band All these calculations are for the case of Maroc Telecom, we want to determine the new number of TRx after the replanning:
BEFORE REPLANNING: Calculation of the reuse factor for the Asilah area: The number of existing cells is Nbr_TrX (confidential data) with a configuration X / X / X of TRx per cell AVERAGE OF TRX 𝐾= 𝑁𝑈𝑀𝐵𝐸𝑅𝑆 𝑂𝐹 𝐶𝐸𝐿𝐿𝑆 So the reuse factor is: 𝐹 𝑟𝑒𝑢𝑠𝑒 =
NUMBER OF FREQUENCIES 𝐾
AFTER REPLANNING: Calculation of the average of TRx
The Reuse Factor is the same: 𝐹 𝑟𝑒𝑢𝑠𝑒 =
NUMBER OF FREQUENCIES 𝑀
With M = (MoyTRx / number of cells) With a 4.2 Mhz wide band and a 200 kHz channel there are 21 carriers required, So the new GSM band is = 64- 23= 41 frequencies. So the average of TRx is Y (Confidential Data), which implies a maximum configuration of Y / Y / Y for each cell to deploy UMTS in the 900 MHz band. 66
IV.2 Traffic balance between 900MHz and 1800MHz Most operators have both 900MHz and 1800MHz frequency resources, and most current UEs support both GSM900 and GSM1800, so traffic should be balanced between 900MHz and 1800MHz. GSM 1800MHz TRX should be expanded in some scenario. If conditions are met, Co-BCCH networking or dual-frequency networking between 900MHz and 1800MHz can be adopted to increase the frequency efficiency. Correspondingly, cell reselection and handover parameters should also be designed.
Figure 46: The traffic migration to the 900 MHz band Process
When an operator decides to reassign GSM frequencies for UMTS, the capacity of its GSM network decreases, so in order not to degrade the service offered by GSM, the traffic will be transported to the 1800 MHz band which, in most case, is not separated. This step is crucial to avoid possible congestion at the 900 MHz band.
Figure 47: Load balancing after the introduction of UMTS 900
To prove that the capacity of the network will decrease, we did the calculation for a real case: We collect voice traffic in peak hours per day, and with the Erlang B function (this function allows
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you to determine the probability of attempted calls during network congestion depending on the load and the number of calls), we reduce the number of TCH for this traffic.
After the introduction of UMTS 900:
The number of TRX ≤Y The number of TCH = TRx number * 7 Time slot (1 TS is for BCCH or signaling) So the traffic Half Rate = TCH * 60% The difference between the traffic flow before and after is positive so we have less capacity and an extension is needed. The only solution is to balance traffic to DCS 1800.
IV.3 GSM900 traffic migration to the UMTS900 & UMTS2100 When UMTS is deployed, some CS/PS traffic can be migrated to UMTS, and hence the capacity demand of GSM will decrease. But this strategy depends on the penetration of UEs that are supported UMTS. Also the operators’ fare strategy can have the impact the migration volume.
V.
U900 Project Process
Like every Huawei project, the U900 network will follow five essential phases:
Preparation. Establishment. Planning and optimization. Acceptance. Closing.
V.1 U900 Planning Process V.1.1 U900 Frequency Plan The frequency allocation to UMTS900 is the first step required to the implementation of the 3G network in the 900 MHz band. Recall that the principle of re-farming is to remove part of the GSM frequency spectrum and reassign it to the new UMTS900 network. To do this, it is imperative to study the frequency band allocated to the Maroc Telecom GSM900 network to identify the most appropriate type of frequency allocation. The frequency band allocated to Moroccan mobile operators by the ANRT (National Telecommunications Regulatory Agency) for the GSM network in 900 is as follows:
Uplink: [890 MHz - 915 MHz]
Downlink: [935 MHz - 960 MHz]
Each frequency for the GSM system is connected with the number of one sequence called ARFCN (Absolute Radio Frequency Channel Number) by the equation below: 68
UPLINK: f (n) = 890 + n*0,2 MHz DOWNLINK: f'(n) = f(n) + 45
While MAROC TELECOM uses the channels numbered from 16 to 79 for the GSM network in the band 900MHz. The type of Sandwich frequency allocation (used by Huawei) consists of reuse for the UMTS900 a frequency band located in the middle of the band allocated to the MAROC TELECOM GSM900, using channels between 46 and 68.
Figure 48: GSM900 frequency band used by Maroc Telecom
The first planning step is to release the frequency band which contains TCHs and BCCHs between 46 and 68 of GSM900 which will be replaced later by the U900 network, to extract a frequency plan.
V.1.2 Buffer Zone Planning The goal behind Buffer zone planning is to avoid intra-frequency interference between GSM 900 and UMTS900, It mainly based on two criteria: Distance: It is necessary to respect a distance of 10 to 15 km between the U900 sites and GSM900 sites. Direct Visibility: For buffer zone sites it is not necessary to plan all the sites belonging to it, just plan cells with a direct line of sight with the U900 zone.
V.1.3 DCS 1800 Sites Planning The 2G cellular system is usually divided into two systems, GSM900MHz system with 124 channel and DCS 1800MHz system with 374 channel with a width of 200 KHz, The DCS1800 frequencies are calculated by the following equation:
Uplink: f (n) = 1710.2 + (n-512)*0,2 MHz Downlink: f'(n) = f (n) + 95 69
MAROC TELECOM uses channels between 512 and 560 for the DCS1800 network UMTS900 Solution Deployment Requires Addition of DCS 1800 Sites in co-existence with GSM900 in the areas where we want to deploy our solution to share the traffic between these two bands. The Parameters Used For DCS1800 Site Planning:
LAC Location Area Code
Code used as a unique reference for the location of a mobile subscriber, this code is necessary to address the subscriber in the case of an incoming call.
CI Cell Identifier Identity number of the cell in the localization area, it is unique in each LAC.
BSIC Base Station Identity Code
Allows the MS to distinguish 2 cells using the same carrier frequency (BCCH). So inside a Cluster, we can use the same BSIC (value between 00 and 77).
Figure 49: Base Station Identity Code
NCC: Uniquely identifies cells with the same references but belonging to a foreign network.
BCC: Differentiates neighboring cells from the same cell and shares the same BCCH frequency
AZIMUT The angle in the horizontal plane defining the main direction of propagation of the antenna
Frequency planning: BCCH et TCH 70
For TCH and BCCH frequencies must be planned in the Maroc Telecom ARFCN range between 512 and 560.
V.1.4 U900 Sites Planning After activating DCS1800 sites to migrate traffic, comes the 3G planning stage of the new U900 sites. To do this, it’s used the U-Net software, the allocation of frequencies to cells that is done in GSM no longer takes place in 3G, those cells are characterized by the use of codes. However we must perform a code planning: assign each cell its scrambling code SC. However, these codes are numerous enough that the problem of planning is less complex than that of GSM.
V.2
U900 Optimization Process
The optimization process is a periodic cycle to which we can call several times in the same mobile communication network after the deployment of a network. Optimization operations respect this cycle which repeats itself as long as these operations always bring improvements to the network. This cycle uses several tools in order to carry out a global study on the network and to get rid of the various problems and then to try to find for each problem the most suitable solution.
Initial Drive Test
Analysis
Proposal of Actions
Application of Changes
Problem Solved?
Verification Drive Test
Analysis
Final Report Figure 50: Optimization process cycle
The performances of the U900 network are related to the optimization of the problems of the bad coverage, the Cross, the Overshooting, the problem of the Handover ..., the resolution of its problems is done according to the analysis of the following parameters: RSCP, Scrambling Code, Ec / Io, etc.
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The purpose of this analysis is to be proactive, that is to work to detect anomalies in the network as soon as possible, and resolve them by planning corrective actions. The Genex Assistant tool makes it possible to determine the values of the KPIs throughout the course of the Drive-Test, these KPIs make it possible to monitor the GSM/WCDMA network and evaluate the performances, and they can also be used to identify the worst performing sites and therefore those which should benefit from optimization or improvement. For a better optimization of our network we are called to answer to the following needs: To be able to collect the data, and the parameters relative to each cell, as well as the statistics on the indices of performances, to make simulations and prediction of the proposals to verify the impact on the network, effectively use this data to analyze problems with optimization tools.
V.2.1 Drive Test optimization Drive Test Tools The Drive-Test is an essential part of the optimization process, it is the best way to locate and analyze a problem geographically. It consists of tests of the performance of the network by driving around the streets with a car, so it gives information on the down track path between the NodeB and the UE, Radio engineers at HUAWEI use different software, including GENEX Probe which is used to perform acquisitions during Drive Test measurements, for later analysis using GENEX Assistant. The tools used in the Drive Test: o Track Mobile: one or more, each is used to make the measurements for a specific test to make the course only once. o GPS: determine the geographical position for each measurement point. o Laptop: equipped for the acquisition, recording and processing of the measurements taken from the mobile and the GPS receiver allowing the DT to visualize the measurements in real time using PROBE GENEX.
The data is then recorded by the software with a precise format extention (.gen) on a file called "Log file" and transmitted to the radio engineer to analyze it with another auxiliary software (Genex Assistant for Genex Prob) and to draw conclusions and proposals improving the state of the network.
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Figure 51: Drive Test Tools
Drive Test Types There are two types of Drive Test: Single Site Verification (SSV) and Cluster Drive Test Single Site Verification (SSV) The purpose of the SSV is to check the availability of services at each site. In other words, it's about checking that the site is functional by testing basic functions, we perform a number of tests that may show faults in the installation. Static Tests From the recordings made by the Genex Probe software with the DT engineer, the RF engineer must perform an analysis of the results that are received. The table below gives us an idea of the parameters generated by GENEX Assistant that we must check the thresholds imposed for each of these parameters. If they do not conform, the tests must be repeated.
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Parameters PSC (used to distinguish the different transmitters: terminals / cells in uplink / downlink respectively). CELL ID (code allocated by the operator to each cell to identify it). LAC (used to identify the location of different regions). Azimuth horizontal angle of the antenna UARFCN (Terrestrial Radio Access Absolute Radio Frequency Channel Number) used to identify a frequency in the frequency band UMTS. RSCP (Received Signal Code Power) signal level received by the mobile station. Ec / Io energy level chip on interference HSDPA Download Average Speed (kb / s): the down flow. HSUPA Upload Average Speed (kb / s): the Up flow
Requirements and thresholds
The PSC, LAC, Cell Id, UARFCN values of each sector of the site recovered from Engineering parameters should be compared with those measured by the MS.
Must be greater than - 85 dBm Must be greater than -9Db The download rate must be greater than 1000 kbit / s Upload rate must be greater than: 1000 kbps
Table 8: U900 parameters and thresholds
Dynamic tests It is a set of tour around the site within a radius of approximately 100 meters. These tour concern the two modes of operation (Idle / connected mode) and which make it possible to determine the coverage the flow that can provide the sectors of the site, to visualize the level of the interferences, if it is possible to realize a handover between the various 3G generations to 2G in connected mode as well as the re-selection of the network in Idle mode this is ensured by the following logs files:
TOUR LONG CALL (TR-LC) TOUR DOWNLOAD (TR-DL) TOUR HandOver (TR-HO) TOUR RESELECTION (TR-RES)
Drive Test Road Static Test Point
Figure 52: The path of SSV Test
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Verification of parameter configuration in IDLE mode: After running the static test log files, the parameters to check are: Frequency used in DL: check that this frequency corresponds to the planned frequency LAC: Check that it matches the planned configuration. Scrambling code: check that the PSC used corresponds to the planned one. Check whether the RSCP and Ec / Io received by the EU are above the required thresholds.
Verification of services in connected mode These tests consist of executing a series of calls and a series of downloads in the periphery of the site whether in a fixed position or in mobility. These tests are divided into: -
Short call (short calls) of 45 seconds, consists of initializing a call that will be completed (stopped voluntarily) after a certain period of time. This call will be stopped each time and restarted. The test is performed to measure accessibility performance but also provides level and signal quality information.
-
Long call (long-term calls) makes it possible to record measurements for as long as necessary in an area. Thus, so early that the call is cut (involuntary cut), the mobile automatically retries another call. This type is used to measure the performance of Handovers and others.
Cluster Drive Test: The Cluster Drive Test is used to optimize the performance of a set of sites (Cluster). It is performed according to a well-defined path by recording the information required for optimizing coverage, interference detection and Handover inter-cell. The Drive test cluster also concerns short calls programmed using scripts. The goal is to make 2-minute calls with 5-second differentiation in forced UMTS mode, to test call setup problems and download rate.
VI.
Conclusion
In this chapter, we introduced the fundamentals of the UMTS900 solution, its utility, benefits, and its re-farming strategy and traffic management, as well as the planning and optimization process.
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Chapter 4: Case study
This chapter will discuss the steps and methods for deploying UMTS900 technology in the city of Asilah, and confirming this deployment with a series of Driver Tests in the deployment area.
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I.
Steps and methods of UMTS deployment
In order to deploy the U900 we have to go through several steps; first the collection of information on the existing configuration of 2G in the city of Asilah, then the planning of the buffer zone, the hardware configuration of U900 sites, as well as the operation of configuration G900 sites changes.
I.1
Existing configuration of the 2G
Figure 53: G900 sites in the city of Asilah
Figure 54: 1800 DCS Sites in the city of Asilah
Asilah is a port in northwestern Morocco of about 30,000 inhabitants, about forty kilometers from Tangier, in the region of Tangier-Tetouan. 81 sites and a total of 233 TRX were set up to provide GSM service in the 900 MHz band. The adopted configuration is S444 for G900 or 4 TRX per sector. In the case of DCS 1800, the city of ASILAH has 66 sites and the site configuration is S444. For the test deployment of the U900, 15 sites were chosen and are located partly in the Asilah-Tangier highway and in the city of Asilah. 77
I.2
Buffer Zone Planning
Buffer Zone Area
1. 2. Planification de la Buffer Zone
U900 Area
Figure 55: Zone U900 et Zone Tampon de la ville d'Asilah
The chosen Buffer Zone planning method is that of the Coverage Prediction and especially overlapping areas in the area that the U900 will occupy. UMTS will use some frequencies in the original GSM band, these frequencies are still used by the GSM outside the U900 zone, and as a result, the GSM and UMTS sites which are close to each other, will cause interferences. The Buffer zone solution is going to be used to solve this problem. Planning is done using GENEX U-net simulation and planning tool. In order to detect G900-configured cells that are only likely to overlap U900 cells, we used the overlap detection method where a mobile in these areas will be covered by more than one cell. If only GSM900 cells are present in overlapping areas near U900 sites, then they are sized as Buffer Zones.
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The recovery card allows us to distinguish areas where the mobile will be covered by one or more transmitters:
Figure 56: Recovery Zones -Asilah-
After detecting areas of overlap of two or more sites overlap, responsible cells are put in buffer zone.
I.3
GSM Reduced configuration of test sites
When the operator decides to dedicate a portion of its GSM900 frequency band for the UMTS900 implementation, the capacity of the GSM900 network is reduced, so it is necessary to reduce the configuration of the test sites.
Targeted Configuration:
Before Re-farming
After Re-farming
12.2 GSM
900 Mhz
8 GSM
10 M
1800 Mhz
10 M
GSM 900 : Configuration : S4/4/4
GSM 900 : Configuration : S3/3/3
Table 9: TRX G900 configuration before and after re-farming.
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In order to reduce the number of GSM TRXs allocated without a negative impact on the performance of the service, a traffic survey per site is required. Although the current site configuration is S444 or 4TRX by sector, most chosen sites for the U900 do not use all these TRXs in their entirety, so it is more convenient to make some changes to increase their capacity. The study we have done is a dimensioning of the GSM900 TCH channels. To do this, we have information on the current traffic and configuration of U900 sites and Buffer Zones as well as the current traffic value for each sector. Before starting the calculation we estimated a traffic increase of 20% and an increase of the configuration of TCH channels in Half Rate (half-rate) in 80%. Using the Half Rate significantly increases network capacity by using two TCH channels on a single Time slot. After these estimates, the new required number of TCH and TRX per sector is calculated. If the result of the calculation shows that more than 3 TRXs are required per sector, other actions must be maintained. The following table shows the different results for U900 sites and sites included in the Buffer Zone:
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Table 10: Sizing of U900 sites and buffer zone
After all calculations, we notice problems at a few sites. The ouled_Abdelessamed site, problems were noted; the configuration calculates for the GSM900 is 4 TRX for the first sector and 6 for the second. A solution would be either to implement the DCS1800 to migrate some of the traffic and lighten the GSM900 load, or implement the SRAN to increase the capacity of the site.
For the site named Sidi_Yamani, although no more than 3 TRX are required the traffic is quite high. To avoid congesting the network, a 100% TCH configuration in Half Rate is required to increase the capacity of the site.
I.4
U900 Hardware Integration in SRAN Sites
The exploitation of the already existing GSM infrastructure is a major advantage for the IAM operator. Indeed, the deployment of the UMTS 900 network is made from BTS and GSM antennas (900 MHz) already deployed, which will save considerable installation costs and equipment. The hardware deployment scenario for UMTS900 processing is shown in the following figure:
Figure 57: Configuring the BTS with U900
The UBBPd6 board card process the WCDMA signals, is connected to the WRFU radio module for processing in the 2100 band. To support the UMTS900 we added a CPRI cable that we connected to the MRFU radio module from the UBBPd6 board. The MRFU module is responsible for radio processing in the 900 MHz band of GSM and UMTS. It is connected in the same way to the GTMU card. The MRFUs are then connected to the antenna that is already deployed for GSM in the 900 band. 83
II.
Drives Tests
To ensure the proper deployment of the U900 and identify the various changes that can be made afterwards in terms, Drive tests were conducted before and after the deployment that we analyzed to better see the improvements and possible degradation that the network has suffered from after activation of the 900. After the Drive Test performed, the Genex Probe software save us a log file to analyze the various measurements performed, and this by using the software of the same GENEX family: Genex Assistant which presents its interface as follows.
II.1 Drive Test Statistics and Measurements for 2G II.1.1 Statistics and distribution of received Rxlev signal level before and after U900 activation The RxLev represents the power level from the BTS and measured at the mobile. It makes it possible to characterize the state of coverage of the zone studied. We then distinguish the RxLev Full which is a measure on all the bursts of the frame without exception. The table serves as a reference for analyzing the different Rxlev value. Rxlev (dbm) -110 a -95 -95 a -85 -85 a -75 -75 a - 65 >= - 75
Signal level No coverage Bad coverage Pretty good coverage Good coverage Very good coverage
Table 11: Rxlev references
Rxlev (The City) Before
After
Figure 58: DT Rxlev int Asilah city
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Rxlev (Highway) Before
After
Figure 59: DT Rxlev in Highway
Based on the results of measuring the level of coverage of the Rxlev signal, before and after Re-farming, it is clear that the latter does not have a serious impact on 2G coverage. The following table compares the different coverage percentages of the following signal before and after re-farming.
City Rxlevel >= - 75 dBm -75 dBm > X> - 85 dBm = - 75 dBm -75 dBm > X> - 85 dBm
