Sci.Int.(Lahore),26(2),613-620,2014
ISSN 1013-5316; CODEN:SINTE 8
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PERFORMANCE ENHANCEMENT OF END-TO-END QUALITY OF SERVICE IN WCDMA WIRELESS NETWORKS Waseem Abbas1, Nasim Abbas2 and Uzma Majeed3 1
Computer Engineering Department, UET Taxila, Electronic Engineering Department, MAJU Islamabad, 3 Computer Engineering Department, UET Taxila Pakistan [
[email protected],
[email protected],
[email protected]] 2
ABSTRACT: In this paper we proposed user satisfaction architecture for packed-switched services in 3rd generation cellular networks for end-to-end Quality of Service (QoS) provisioning in Diffserv IP network environment. The paper focuses on mapping of QoS classes from Diffserv to UMTS, Admission control, Buffering and scheduling. The Diffserv code point was utilized in the end-to-end quality of service provisioning to differentiate various type of multimedia real time traffic. This paper proposes the WCDMA based prioritized uplink call admission control that combines the QoS tolerance and service differentiation for data and multimedia traffic by priority. This algorithm reserves some bandwidth margin, number of users and power consumption to decrease handoff failures to give preference to high priority calls, such as handoff calls additionally Low latency queuing (LLQ) is implemented to improve the quality of service. LLQ is used with the key idea of mapping voice and video traffic in two different queues but at the same time using priority queuing within LLQ for both voice and video traffic for all other QoS classes. The results obtained from simulations demonstrate that proposed algorithm meet the QoS requirement. Keywords: CAC, DiffServ, EURANE, LLQ, NS- 2, QoS, Scheduling
1. INTRODUCTION Third generation mobile communication technologies have gone through a very rapid growth and Universal Mobile Telecommunication System (UMTS) has emerged as a leading standard for the provisioning of third generation cellular networks. Wireless 3G network is anticipated to convey multimedia traffic such as VOIP, video telephony, data and other applications. The requirement of QoS while transmitting multimedia traffic on same medium is one of the major issues in order to design and analyze 3G wireless networks. Service classification and efficient resource management are quite demanding tasks due to increasing number of applications and ubiquitous bandwidth limitations for multimedia applications such as voice and video streaming. Key advantage of UMTS is its ability to provide different services with QoS guarantees [1]. IETF standardized two different mechanisms for providing QoS in IP networks Diffserv [2] and InterServ [3]. DiffServ can be implemented in UMTS with no management complexity, while InterServ have scalability and complexity problems. DiffServ uses Codepoints known as Differentiated Services code points (DSCP) attached with IP header of a packet to classify traffic with different PHBs (Per Hop Behavior) at the boundaries of the network. PHB definitions do not specify any particular implementation mechanism and therefore implementation problem of PHB has gained noteworthy attention. On the other hand, QoS concept and architecture for UMTS network as specified in 3GPP [1] focuses on QoS signaling from user equipment to GGSN only, and it does not support the QoS mechanisms for data transport. For end-to-end QoS provisioning in UMTS, it is required to map the IP traffic classes to the UMTS network
and propose a QoS mechanism for the transport of user data. Existing work on end-to-end QoS in UMTS [4] have analyzed advanced mapping between voice and video telephony but do not take other UMTS traffic classes into account. Other work investigates the access control (AC), in both the wired and wireless network part, a multi-class AC scheme on the wired network part was proposed in [5], which supports the DiffServ approach. Authors in paper [6] have combine WFQ and LLQ, but the main flaw of this idea is the property that delay in video conferencing could be reduce but at the same time voice traffic got the maximum delay time. The SEACORN [7] project contributed in the development and implementation of wireless part i-e. Radio Resource management RRM algorithms for QoS provisioning in the UMTS network. One of the major contributions of the SEACORN project is a UMTS extension for the Network Simulator 2 (NS-2) [8] known as Enhanced UMTS Radio Access Network Extension (EURANE) [9]. We choose EURANE as the tool to simulate an E2E UMTS QoS scenario. This paper proposes detailed algorithm in which concept of mapping voice and video telephony to different QoS classes, idea of implementing LLQ scheduler and packet treatment strategies for the UMTS core network and analyzes them in a large set of simulation experiments. The latter focus on revealing the impact of non-real time services on real-time services in different scenarios with and without full QoS provisioning mechanisms. The mapping will be done in the GGSN and scheduling, policing and multiple queuing mechanisms will be implemented in the UMTS Core Network.
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ISSN 1013-5316; CODEN:SINTE 8
This paper is structured as follows. Section II presents the proposed algorithms and mechanism, Section III explains the simulation scenario and simulation results. Section IV concludes the paper and describes direction of future work. 2. END-TO-END QOS MECHANISM The aim of this section is to give the brief idea of development of E2E QoS algorithm in terms of QoS mapping, Call Admission Control, policing, buffering and scheduling. 2.1 General Assumptions and optimization target In our proposed algorithm which is depicted in Figure 1 for provisioning of E2E QoS algorithms. There are three main components of UMTS System architecture User Equipment UE or Terminal Equipment TE, UMTS Terrestrial Radio Access Network (UTRAN) and Core Network. Core network is connected to external IP domain network in which there are edge router and application servers which can send only one type of application data. GGSN and SGSN are the entities of UMTS core network and UTRAN contains Radio Network controllers RNCs and Node-Bs, which are responsible for all functionality related to radio access. In our scenario both external network and UMTS network supports DiffServ. Application Servers send downlink data packets to the UEs and these packets will be controlled by Edge router, GGSN and SGSN before it is segmented to RLC PDUs in RNC and forwarded to Node B and in our proposed algorithm only PDUs transmitted via Dedicated Transport Channel to UEs are considered. UMTS CORE NETWORK
UTRAN
EXTERNAL NETWORK VOIP
UE UE
UE
VIDEO
Node-B
RNC
SGSN
GGSN
EDGE
UE
Sci.Int.(Lahore),26(2),613-620,2014
In our scenario, the bottleneck of the downlink transmissions is presumed to be the outgoing link from the GGSN to SGSN hence the design target is to enhance the bottleneck link consumption i-e minimizing session blocking rate and higher link throughput while maintaining the E2E QoS requirements of each UMTS class. The boundary conditions of each service type are shown in Table 2. Table 2: UMTS QoS Requirements of each service class Service Conversational Streaming Interactive BackType ground SDU Loss < 10-2
