802 11p Protocol For Vehicular Wireless Networks Computer Science Essay

The study has chief portion as Results, which is divided into two parts “ Radio ” and “ System ” The wireless portion discusses the Modulation technique ( OFDM ) , the 2nd portion Radio Definition explains the figure of channels, channel bandwidth, and the intent of the channels, and the eventually the Existing Traffic System in item. The system portion elaborates the Intelligent Transport System and the most of import issue in communicating is the Security of the web and the information. Finally conclusion portion makes the concluding words about the treatment. .

802.11p extention is one of the extentions under development for the 802.11 protocol. Being implemented in the traffic systems in vehicles and along the roads. The protocol is an extention to 802.11 and besides extension to 802.11a/g as these protocols serves as footing for the development of 802.11p. Different services can be provided in the signifier of information about nearby traffic, the toll aggregation and the parking fee etc.

802.11p undertaking is the portion of ITS Intelligent Transport System, vision of an intelligent traffic system, perchance taking towards self goaded vehicles in normal traffic.


This study explores 802.11p extention what it can supply. The already in topographic point traffic systems which are supplying aid to vehicles and drivers ( RDS ) traffic information system will besides be brought up and compared with 802.11p. As 802.11p is a public web so the security aspects has besides been examined.


We have divided the consequences in to two parts. The “ Radio Part ” which deals primly with the wireless specifications for 802.11p extention, which includes the basic comparing to GPS / RDS, based traffic information systems.

The “ System Part ” trades with the intelligent systems in general, presenting the constructs of ITS and security of vehicular communications.



OFDM is the combination of transition and multiplexing to use the channel more efficaciously and increases the spectral efficiency. Which makes it the most used transition Technology today. The basic working of OFDM in a channel is subdivided into multiple little narrow set channels and symbols are so transmitted through these sub channels. The perpendicularity between the channels makes it possible that no 1 channel interferes the other. These are the transition techniques for OFDM: BPSK.QPSK, 16QAM and 64QAM.

Radio Definition

802.11p is non like other 802.11 wireless definitions, which operates on unaccredited wireless set, on the other manus it operates on the licensed Dedicated Short Range Communication ( DSRC ) bands. It uses 5.9 GHz and 5.8 GHz in US and Europe / Japan severally. It uses the OFDM transition which uses seven 10 MHz broad bomber channels with a 5MHz broad guard set.

There is a halfway bomber channel which is used as control channel, and the upper and lower bomber channels are dedicated for particular utilizations, such as for exigency vehicles to signal traffic.

In order to cover larger country, four different categories for transmittal power are defined where the highest 1 is 44dbm ( 30watts ) , allocated for exigency vehicles. This can be compared to the 802.11a amendment, for which North American channels are restricted to 40mw, 200mw or 800 mw depends on class. The maximal scope of about 1km allows for the wider arrangement of entree points.

When 802.11a / g were developed it was assumed that the channels would be inactive, but non the instance sing traffic. Due to the motion of vehicles, non merely the channel varies over clip, but Doppler displacements will besides be considered as vehicles can make high velocities in opposing waies.

Symbol rate is 8.0Aµsec for DSRC with 1.6Aµsec guard set interval with a signal bandwidth of 10MHz. DSRC uses 64 bomber bearers with merely 52 sub bearers used for transmittal. Out of 52, 4 are pilots used for stage trailing, while remainders of the 48 are used for informations.

3.1.3 Existing Traffic System

The 802.11p protocol is designed to supply traffic information. There are besides the similar systems for these services bulk of the GPS receiving systems can have informations via RDS and already covers about ( 98 % ) of Sweden. The traffic message channel ( TMC ) information is sent with a regular wireless plan, in Swedish instance with P3.

The benefit of utilizing TMC 802.11p for information transmittal is that it uses already existing substructure, with a considerable transmittal scope. The auto GPS receivers that utilize TMC informations are common today ; many automobilists already have entree to reliable traffic information.

With the engineering range of TMC with 802.11p, it can supply information about auto clang, blocked roads or even bull battles, it is limited to supplying traffic information from a centralized beginning. The fire truck or ambulances equipped with 802.11p could signal nearby traffic in more effectual mode so a horn and blinking visible radiation.

One of the facets of the TMC is security. TMC information is transmitted in field text with least one application developed in 2007, is capable of shooting false traffic information utilizing inexpensive electronics. This false message could be about roads closed, that a bomb onslaught had occurred few of the illustrations. This would be discussed exhaustively latter on.


3.2.1 Intelligent Transport Systems

ITS is a wider construct of Engineering betterments to transit systems utilizing information and communicating engineering. The Improvements purpose to fuel efficiency, clip efficiency, hazard efficiency, burden efficiency etc. As with all information systems, surveillance and monitoring is another facet where ITS, can supply extra sweetenings.

Under ITS, there includes systems that have been in being for many old ages. Some of them includes old detector nodes placed over roads either temporarily, or built-in into the roads for good, frequently installed at traffic visible radiation controlled intersections, with the intent of numbering vehicles, which can be used for traffic planning during haste hours etc.

ITS is divided into three phases.

1. Datas Collection

Detectors, acquisition of informations, cell phone places, electrical traffic accounting, automated wireless based traffic toll systems, picture based traffic toll systems etc.

2. Datas Communication

Collected informations by and large has to be communicated someplace.

3. Data Calculations

Then information is processed i-e possible actions are taken ( and perchance communicated to histrions ) .

802.11p is concerned with the communicating phase within a subset of all ITS communicating, which concerns communicating between vehicles and other vehicles, or vehicles and substructure.

3.2.2 Security

Security is the most of import facet, vehicles communicating can be used, but at the same clip the applications which are traveling to function might do alluring marks for cyber felons. Examples of possible marks may include automatic toll system, parking system and traffic safety messages.

There are documents and work available sing the issue of security in vehicular communicating which discussed the information types, flags and construction of messages that are passed across radio webs. The messages can be protected against different sorts of onslaughts such as eavesdropping, burlesquing, change and message reuse, other concerns include different types of system theoretical accounts, communicating theoretical accounts, adversary theoretical accounts and design rules.

Two of the most concerned security facets are Non-Repudiation and Confidentiality, Integrity and Availability ( CIA ) .

Non- Repudiation means if any entity takes an action, it can non deny it. A basic illustration would be bar of the spreading of false messages or denial of service onslaughts, as beginning of information can ever be tracked.

Confidentiality, Integrity and Availability ( CIA )

Confidentiality means that the individuality of the users should be protected against an unauthorised party, so that they can non utilize other user ‘s profiles. Integrity means hallmark is required to halt unauthorised messages. A timing system can be employed to keep the freshness of messages and avoid repetition messages. Availability is achieved through the routing protocol.


The possibilities introduced might take to a safer and drum sander traffic flow, due to information provided to automobilists sing exigency vehicles and traffic conditions, every bit good as the possibilities of roll uping toll and parking fees transparently. The use of vehicular communicating might besides implore a few inquiries with respects to privateness, and the possibilities of tracking unwilling automobilists. This is nevertheless far outside the range of this study.

802.11p based engineerings has two interesting betterments over bing engineering nevertheless, decentalisation and dependability. With Ad-hoc webs formed on the roads, automobilists are no longer limited to information distributed by a cardinal bureaucratism or concern, but can interchange information straight over comparatively big distances. Increased dependability is associated with decentalisation in the increased figure of beginnings of information.

Implementing 802.11p requires immense investing as entree points will hold to be established every few kilometres on roads. Which makes it improbable that any deployment of 802.11p engineering will be seen in the following few old ages?

Documentation is largely limited to IEEE articles and a few articles published by auto makers, doing information on the undertaking more scare, as the motives for doing publications is missing, due to the pure industry involvement in the field.

Review Question

Which 802.11 engineering 802.11p based on and why was the old engineering non plenty for radio vehicular communications?