Proceedings of the International Multiconference on Computer Science and Information Technology, pp. 627 – 631
ISBN 978-83-60810-22-4 ISSN 1896-7094
CAR-to-CAR COMMUNICATION SYSTEM Juraj Miček
Ján Kapitulík
University of Žilina Faculty of Management and Informatics, Univerzitná 8215/1, 010 26 Žilina, Slovakia Email:
[email protected]
University of Žilina Faculty of Management and Informatics, Univerzitná 8215/1, 010 26 Žilina, Slovakia Email:
[email protected]
Abstract — In near future number of cars with ability to communicate with each other as well as road infrastructure will be growing on European roads. The article describes problematic of ad-hoc wireless car-to-car and car-to-road infrastructure communication system.
I. INTRODUCTION OAD transport is one of key sectors of European industry. The sector employs more than 9% of the entire EU workforce, generating a turnover that amounts to 20% of the Union GDP. It is responsible for over 75% of inland freight transport and, as such, plays a crucial role in all European industrial and commercial activities, [1]. Road transport generates about 25% of CO2 emission of EU. Reducing emissions from road transport is a particular challenge given the anticipated demand growth of around 32% in passenger kilometers by 2020, [2]. Estimated financial losses related to road accidents are about 200 billions €. Human being factor is responsible for almost 90% of them. Referring to previous information, European society decided to reduce number of accidents by 75% to 2020. Understanding current trends, it can be stated that it will not be possible to reach defined goal without radical changes concerned road transport systems. This is reason why European society decided about 4.1 billion € investment into research and development in the field of road transportation systems by 2013. Present day communication technologies as well as microelectronics allow production of reliable and low energy consumption devices suitable for intelligent transport systems (ITS) applications. That is why improvement of traffic safety and efficiency on the basis of communication system implementation is the subject of interest of present days.
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II. COMMUNICATION SYSTEM C2X In 1999, U.S. Federal Communication Commission (FCC) allocated 75 MHz spectrum at 5.9 GHz for Dedicated Short Range Communications (DSRC) devices to be used for car-to-car as well as car-to-infrastructure communications. The primary goal of above mentioned decision was to improve traffic flow and safety aspects of public road transport. The initial effort at standardizing technology took place in the ASTM. In 2004, this effort migrated to the IEEE 802.11p working group to be responsible for preparation of communication standard for Wireless Access in Ve627
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Fig 1. Illustration scheme of communication system C2X
hicular Environments (WAVE), which would be accepted all over the world. Fig.1 illustrates basic subsystems of communication system C2X: ● Car-to-Car communication subsystem (C2C) enables communication between cars via On-Board Units (OBU). ● Car-to-Infrastructure communication subsystem (C2I) enables communication between car and road infrastructure elements via OBU and Road-Side Units (RSU). ● Transportation Management Center-to-Infrastructure communication subsystem (TMC2I) enables communication between Transportation Management Center (TMC) and road infrastructure elements. III. SERVICES OF COMMUNICATION SYSTEM C2X It is clear that communication system to be characterized by safety and reliable communication between car and road infrastructure elements as well as cars by themselves could significantly improve road transport safety, traffic effectiveness and user comfort of transport systems. “C2X” services could be principally categorized into next classes:
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mal speed advisory, traffic flow assistant system, dynamic routing, navigation to free parking lots, localization services and etc., - present communication standards are used, e.g. TCP/IP. Services related to other applications - remote car diagnostic and on-board databases
actu alization, payment services (road, parking and fuel fees, etc.), access system control, car remote control, internet applications, information services: info about gas stations, restaurants and other interesting points, localization security services (fast localization of stolen cars), etc., - communication protocols and standards selection is coordinated with third party. IV. TECHNICAL SOLUTION OF COMMUNICATION SYSTEM C2X Core module of road transport system is represented by communication unit, which is able to meet all requirements of transport applications. It must allow reliable and secured data transmission implemented on road-side units and car on-board units as well. In compliance with [4], for reliable communication is necessary to use two communication channels: Channels dedicated to applications C2C - network management and safety critical applications (control channels), safety critical applications, applications for traffic efficiency improvement, non-safety related applications. ● Public channels - according to Std. IEEE 802.11a/b/g in compliance with regional limits. Internet access, information and game applications are complementary services of C2X communication system. This is reason why they are using exclusively channels for non-safety applications or public communication ones. Communication unit can support other communication systems – GSM, GPRS, UMTS, HSDPA, WiMax, 4G and etc. In 5.8.2008, EU Committee decided to allocate frequency band from 5875 to 5905 MHz for ITS applications, which is going to be used on non-exclusive basis. Channels allocation is illustrated in Fig.2. European Telecommunications ●
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first aid and security preference services, - special communication protocol is used. Services related to traffic efficiency - navigation systems actualization, green light
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work warning, change of lane warning, zebra and rail crossing warning, weather condition warning, infrastructure relief warning, speed limit warn-
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Fig 2 . Frequency bands allocated for communication system C2X
Standards Institute (ETSI) defined following frequency bands for communication system C2X: - 10 MHz band from 5.885 to 5.895 GHz for network management and safety critical applications (control channel), - 10 MHz band from 5.895 to 5.905 GHz for safety critical applications, - 3x 10MHz bands from 5.875 to 5.885 GHz and from 5.905 to 5.925 GHz for improvement of traffic efficiency and other safety applications, - 2x 10 MHz bands from 5.855 to 5.875 GHz for nonsafety-related applications. At maximal permitted transmit power of on-board units: 33 dBm@10MHz will be possible to attain communication distance in range from 500 to 1000m (conditioned by direct visibility). Typical distance between two successive vehicles at speed 120km/h is 60m. Transmit power 3dBm is expected in this particular case. Communication distance will be controlled by transmit power controller (TPC) in range of minimally 30dB. Communication system will support dynamic control of transmit power with minimal power level of transmitter: 3dBm. Expected data rates will be: 3, 4.5, 6, 9, 12,
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JURAJ MIČEK ET. AL.: CAR-TO-CAR COMMUNICATION SYSTEM
2 3
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TABLE II. TECHNICAL SPECIFICATIONS OF COMMUNICATION UNIT OTTO ON BOARD™
d B
2 0 1 0
[ G
H
Parameter
z ] 5 .9 3 0
5 .9 2 0
5 .9 1 0
5 .9 0 0
5 .8 9 0
5 .8 8 0
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5 .8 6 0
5 .8 5 0
5 .8 4 0
5 .8 3 0
- 1 0
5 .8 2 0
0
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e . i. r . p . [ d B m /M H z ]
3 0
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Details
Frequency [GHz]
5.850 – 5.925 GHz (channel 172 up to 184, 178 is control channel)
Bandwidth [MHz]
10
Data Rate [Mbps]
6 Mbps
Receiver Sensitivity
-82 dBm@6Mbps
Max. Transmit Power
20 dBm
Processor
MPC520@396 MHz
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1 7 6 1 7 8 1 8 0 1 8 2 1 8 4 - 6 5
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Fig 3. Power limits of ITS transmitting devices at frequency band 5.9 GHz
18, 24, 27 Mb/s. Communication unit will support halfduplex and broadcast mode of data transmission. In compliance with Std. IEEE 1609.4, all radio subsystems of C2X will be receiving messages via exclusive control channel during control time intervals. Synchronization of individual receivers/transmitters will be ensured via GPS signals. This approach guarantees to all communication units receiving critical safety messages during control time intervals. It is expected that European communication system will be able to receive messages simultaneously via two exclusive channels. This concept allows receiving of safety messages even during control time intervals. V. STATE OF ART IN THE FIELD OF COMMUNICATION UNITS DEVELOPMENT Thanks to concentrated effort of research and development teams as well as producers in the field of info-communication techniques for transportation applications, the first commercially produced on-board communication units started being produced at the end of 2008. The units are fully operating according to Std. IEEE 802.11p. The development of physical layer of communication modules was partially simplified because of required technical parameters which are only slightly differentiate
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from WiFi standard IEEE 802.11a. Comparison of the technical parameters is presented in Tab.1. The first radio prototype applicable in the field of ITS at frequency band 5.9 GHz was developed and realized in the USA in 2004. The radio module was named „DENSO radio module“. It worked in two modes: - slow mode – supporting Std. 802.11a for data transmission in case of slowly moving or parking car, - fast mode – operating at 5.9 GHz supporting data transmission in case of fast moving car. This experimental RF module was developed to verify theoretical assumptions and data transmission methods. The production of commercial communication modules, onboard units and development kits at 5.9 GHz frequency band was announced by several producers at the end of 2008. The equipment OTTO on Board™ , claiming by producer, is the first communication module at 5.9 GHz frequency band fully prepared to be mounted into newly produced cars and road infrastructure, [13]. Serial assembly of the modules into American cars is expected during 2009. Both of infrastructure unit (RSU) as well as car unit (OBU) have the same solution and equal fundamental electrical characteristics, Tab.2. On 17th November 2008, another American producer announced finished research and beginning of equipments
TABLE I. COMPARISON OF PHYSICAL LAYER BETWEEN IEEE 802.11 P AND 802.11 A Parameter Data Rate [Mbps] Modulation
IEEE 802.11p 3, 4.5, 6, 9, 12 18, 24, 27 BPSK OFMD QPSK OFMD 16-QAM OFDM 64-QAM OFDM
IEEE 802.11a 6, 9, 12, 18, 24, 36, 48, 54 BPSK OFMD QPSK OFMD 16-QAM OFDM 64-QAM OFDM
Error Correction Coding
64 states, Convolutional Coding with K=7
64 states, Convolutional Coding with K=7
Coding Rate
½, 2/3, 4/3
Number of subcarriers
52
52
OFDM Symbol Duration [μs]
8
4
Bandwidth [MHz]
10
20
Frequency [GHz]
5.855 – 5.925
5.15-5.35, 5.725-5.850 (ISM)
½, 2/3, 4/3
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TABLE III. TECHNICAL SPECIFICATIONS OF COMMUNICATION UNIT EWAVE Parameter
Details
TABLE V. TECHNICAL SPECIFICATIONS OF COMMUNICATION UNIT LINKBIRD-MX Parameter
Details
Frequency [GHz]
5.150 – 5.850 GHz, IEEE 802.11a
Frequency [GHz]
5.725-5.925 GHz
Bandwidth [MHz]
5, 10, 20, 40 MHz
Bandwidth [MHz]
10, 20 MHz
Data Rate [Mbps]
1 to 54 Mbps
Data Rate [Mbps]
Receiver Sensitivity
-94 dBm@6Mbps
6, 9, 12 24,34,48, 54 Mbps in bandwidth 20 MHz 3, 4.5, 6, 9, 12, 18, 24, 27 Mbps in bandwidth 10 MHz
Max. Transmit Power
28 dBm
Processor
AMD Geode LX800@500 MHz
Max. Transmit Power
22 dBm
Processor
MIPS @266 MHz
production supporting mobile solution in the field of road transport. In spite of the fact that offered system is mainly dedicated for car-to-infrastructure unit communication it is not technically limited only for above mentioned application. The equipment MobiWAVE is represented by on-board unit for wireless communication, which is utilizing open Linux platform. It consists of two radio modules – WiFi and DSRC, receiver GPS, 3G and Bluetooth radio. It is important to remember that DSRC radio operates in ISM band at 5 GHz according to Std. 802.11a. As a part of equipment delivery is development environment including reach library supporting WAVE, IP, Web, GPS, Bluetooth and etc. The environment supports fast development of new applications. Compact communication module „eWAVE“ represents one of most interesting products in the field of mobile transportation communication systems. It was developed for implementation into car on-board unit and infrastructure unit as well. The module supports operation modes in relation with Std. IEEE 802.11a,b,g,j,p in data rates from 1 to 54 Mbps. Complete research and testing software package supports fast development of special applications. The dimensions of communication module: 38x27x11 mm allows it to be implemented into final product without strong space reTABLE IV. TECHNICAL SPECIFICATIONS OF COMMUNICATION UNIT EWAVE - MNCU Parameter Frequency [GHz]
Details 2.400-2.484 GHz 4.940-4.990 GHz 5.250-5.350 GHz 5.470-5725 GHz 5.725-5.825 GHz 5.825-5.850 GHz 5.850 – 5.925 GHz (channel 172 to 184, 178 is control channel)
Bandwidth [MHz]
5, 10, 20, 40 MHz
Data Rate [Mbps]
1 to 54 Mbps
Receiver Sensitivity
-88, -91 -97 dBm (p, a/g, b) @6Mbps
Max. Transmit Power
14 dBm
Processor
MIPS 24k@300 MHz
quirements. Range of operation temperature: -45°C to +85°C permits communication module to be used in standard operation. The other equipments supporting ITS applications were developed on the basis of above mentioned communication module. Let us mention MCNU unit, which extends applicability of „eWAVE“ module, [17] . MNCU (Multiband Configurable Networking Unit) consists of processor Pentium grade, 1.5 GHz, 512 MB RAM, 2 GB Flash, OS Linux. 16-channel receiver GPS, temperature and humidity sensors are part of the unit. Modification MCNU R1500S with improved security consists of accelerated security module 1609.2. The equipment LinkBird-MX is communication module developed in Europe. It is a part of the development kit NEC C2X-SDK. The kit supports fast application development in the field of ITS. Technical parameters of the module are presented in Tab.5. Communication unit consists of 64-bit processor MIPS@266MHz, 512 MB NAND Flash, 16 MB NOR Flash and 128 MB SDRAM memory. Supply voltage is in the range from 5.4 to 22V. Input power of the equipment is lower than 5W. Communication unit supports interfaces: 2xUSB, 2x32-bit PCMCIA, MOST, serial interface for GPS, CAN and RS232 as well as network interfaces FE 10/100 Base-T and mini PCI 802.11 a/b/g/p. Software utilities consists of OS Linux Debian Etch, Kernel 2.6.19, UBOOT, configurable controllers for 802.11p. It is available development kit NEC C2X-SDK with geographical routing, safety management services and application interface functions, API. Producer ensures customer support from hardware and software point of view as well. Communication unit represents powerful tool for development and testing of new applications in the field of ITS. VI. CONCLUSION Research and development teams all over the world are focused on the development of wireless car-to-car and car-to-road infrastructure communication systems almost 10 years. It was proposed set of services that could be successfully realized by C2X system. Communication standards development, frequency bands allocation proposals as well as first design and production of communication units was realized in parallel during this time. It is possible to expect that pilot projects are going to
JURAJ MIČEK ET. AL.: CAR-TO-CAR COMMUNICATION SYSTEM
start being realized in 2009. In near future number of cars with ability to communicate with each other and to inform driver about potential accident , restricted speed, low cost of fuel, free parking place and other relevant information will be growing on European roads. ACKNOWLEDGMENT The article „Car-to-Car Communication System“ was written thanks to support of grant VEGA 1/4060/07 „Development of new methods of signal pre-processing for purposes of control and monitoring of technological processes. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17]
ERTRAC, Research framework, March 2008 ERTRAC, Strategic Research Agenda, December 2004 ETSI TR102-492-2-V1.1.1_0.0.16T, Electromagnetics Compatibility and Radio spectrum Matters (ERM); 2006 C2C-CC Manifesto v.1.1, August 2007 T.Kosch: Technical Concept and Prerequisites of Car-to-Car Communication, Munich, Germany, 2006 R. Meitzner: Kick of Meeting SeVeCom, Lausanne, Swiss, 2006 A. Kung: Security Architecture and Mechanisms for V2V/V2I, v.2.0, 2007 Technical Report, ETSI TR 102 492-2 v1.1_0.0.16, 2006 M.Raya, J.P. Hubaux: Securing vehicular ad hoc networks, Journal of Computer Security str. 39-68, 15, 2007 S.S.Lee: Vehicle Communication Network, Hanyang University, 2007 J.Miček: Komunikačný system pre zvýšenie bezpečnosti a efektívnosti cestnej dopravy, Automatizace 4. 2008, ISSN 0005-125X M. Schulze: International Activities – Europe in Comparison to USA and Japan, Berlin, 2006 www.ivhs.com/otto The Otto on board, Technical specifications www.savarinetworks.com MobiWAVE-On Board Unit, Product specifications www.savarinetworks.com StreetWAVE-Roadside Unit, Product specifications www.c2x-sdk.neclab.eu NEC LinkBird-MX www.kapsch.net eWAVE, Embedded WAVE module
631 [18] www.technocom-wireless.com Technical specifications MCNU R1500/R1500S [19] CEPT,ECC report 20, The harmonized radio spectrum use for safety critical applications of Intelligent Transport Systems (ITS) in the European Union, 21.12.2007
