- Level: University Degree
- Subject: Mathematical and Computer Sciences
- Word count: 2911
An Introduction to the IEEE 802.11p WAVE standard
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Introduction
CONCEPT
It is suggested that, by 2012, the market for vehicular communication networks will be a billion-dollar industry. The technology necessary for the implementation of vehicular communication networks is currently under development, and has been drafted under the IEEE 802.11 standard as draft amendment 802.11p. The 802.11p standard relates specifically to the emergence of V2V (Vehicle to Vehicle) and V2R (Vehicle to Roadside) communications. The 802.11p standard has also been referred to as WAVE (Wireless Access in a Vehicular Environment) and promises to deliver an exciting new range of communication devices and applications for use in a vehicular environment. In this report, I will examine the 802.11p standard. 802.11p is a fundamental part of the US Department of Transportation’s DSRC (Dedicated Short Range Communications) project. DSRC supports a bandwidth of 75MHz and operates in the 5.9GHz frequency band. It’s approximate range is some 900 - 1100m[1]. But why develop such a technology? The main applications of WAVE will be relating to that of driver safety; with drivers allowed to be notified of accidents, motorists able to forewarn other motorists of their intentions when merging etc. I will examine these applications in further detail later on in the report after my technical examination. There has been a family of standards devised by the IEEE to deal with the security and management of vehicular communications. These are the 1609.1, 1609.2, 1609.3 and 1609.4 specifications. These specifications relate to Resource Management, Security Services for Applications and Management Messages, Networking Services and Multi-Channel Operations respectively[2][8].
CHALLENGES
Obviously, technology of this scale and nature is going to be inherent with problems that need addressing if it is ever going to be deemed as a success.
Middle
WAVE’S SYSTEM ARCHITECTURE
Having looked at the issues faced by the development of WAVE, I will now conduct a technical examination of this technology.
Vehicular communication transmissions will be sent and received using an OBU (onboard unit). Any vehicular communication devices in a car will also receive data via an ad-hoc connection to this unit. While the OBU will conduct its V2V and V2R transmissions via the 802.11p standard, it will also feature 802.11 a/b/g standards so that it can function with other end user devices such as laptops and PDAs. Of course, the inclusion of such will more-than-likely be vendor specific. The OBU will be picking up transmissions from an RSU (roadside unit) that will be placed in those locations deemed necessary by businesses implementing the provision of V2R services.
In order to facilitate this, the 802.11p standard sees changes made to both the MAC and PHY layers.
PHYSICAL LAYER | The 802.11p PHY layer is quite similar to that of IEEE’s 802.11a standard. There are some differences however[4]. WAVE’s frequency band will be divided into channels, from which all safety messages will be broadcast from the centre channel. Remaining channels will be used amongst various other applications. The 802.11p standard will also see all parameters in the time domain doubled to reduce interference caused by multi-path propagation. As a result of this, 802.11p’s data rate will be halved compared to the 802.11a standard. The frequency bands upon which it will operate are 5.9GHz in the United States, while in Europe the 10MHz band from 5.895 to 5.885 GHz will be assigned to safety and traffic applications. Other applications will function within 5.885 to 5.895 GHz[5][6].
Conclusion
When the concept of vehicular communications matures, the potential for high end applications and devices is considerable. Today’s cars are already equipped with very powerful radios and digital equipment. Implementing V2V and V2R networks into these devices could bring motorists into an age of technological convenience the likes of which they have never seen. Mobile network gaming, video streaming, accessing eMail and other data on the move - the list is endless. Navigation tools can be implemented with wireless updates, perhaps even factoring in real time on-road events. Considering that most cars have a powerful source of energy, the level of devices and interactivity in vehicles could increase considerably when this technology reaches fruition.
REFERENCES
[1] coe.montana.edu www.coe.montana.edu/ee/rwolff/shel%20leader%20dsrc.pdf
Date Accessed: 6-10-2008
[2] wikipedia.org http://en.wikipedia.org/wiki/Vehicular_communication_systems
Date Accessed: 6-10-2008
[3] media.chrysler.com http://www.media.chrysler.com/newsrelease.do?id=5270
Date Accessed: 6-10-2008
[4] Evaluation of vehicular ad-hoc network using IEEE 802.11p, by Lothar Stibor, Yunpeng Zang and Hans-Jurgen Reumerman. Page 2. Published by Philips Research Aachen. Available online at ew2007.org/papers/
[5] C2C-CC Manifesto, Page 41 Available Online at www.car-2-car.org
[6] European Telecommunications Standards Institute technical papers.
[7] Standards: WAVE / DSRC / 802.11p, by Dr Michele Wigle. Page 16.
Available online at http://www.cs.odu.edu/~mweigle/courses/cs795-s08/lectures/5c-DSRC.pdf
[8] US Department of Transport, Intelligent Transportation Systems Standards Fact Sheet, IEEE 1609 Family of Standards.
[9] Inter/Intra-Vehicle Wireless Communication, by Gregory S. Bickel. Viewed Online.
http://www.cs.wustl.edu/~jain/cse574-06/ftp/vehicular_wireless/index.html#sec4
Date Accessed: 7-10-2008
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