Introduction:

The vehicular communications using Wireless Local Area Network (WLAN) technologies are intended for the safety applications to improve the travelling safety on highways as well as non-safety applications to enhance the comfort of driving. Typical safety applications include traffic signal violation warning, emergency electronic brake lights, pre-crash warning, cooperative danger warning message dissemination, lane change warning, etc. Such applications rely on local wireless communications among vehicles and between vehicle and roadside, and have strict requirements on reliability and latency that is usually less than 100 milliseconds. Besides, applications like cooperative forward collision warning require multi-hop operation to cover the Zone of Relevance (ZoR) going beyond the communication range of one hop. However, the non-safety applications, like onboard Internet access, traffic information dissemination and high data rate download, are more bandwidth sensitive. Therefore, efficient congestion control algorithms are needed to prevent the channel resource being exhausted by the greedy non-safety applications and guarantee the Quality of Service (QoS) of safety applications, when the channel resource is shared by safety and non-safety applications.

Congestion control is a cross layer issue involving the application layer, transportation layer, network layer, Medium Access Control (MAC) layer, Physical (PHY) layer and the management plane. The tasks of this student project are mainly concentrated on the MAC and PHY solutions for congestion control based on the IEEE 802.11 WLAN technology. The methodology is to evaluate the performance of the congestion control algorithms, e.g. MAC layer priority differentiation, Station Management Entity (SME) based transmission control and PHY preamble based channel clear, through stochastic simulation. The environment is the Specification and Description Language (SDL) based WARP2 simulator.

Suggested concrete tasks:

In order to achieve the above mentioned goal, a step by step approach is proposed as follows: 

²       Getting familiar with the IEEE 802.11p/IEEE 1609 vehicular communication protocols

²       Starting up with SDL language and WARP2 simulation environment

²       Implementation of different congestion control algorithms in WARP2

²       Performance evaluation and analysis for multiple layer congestion control algorithms

²       Forming corresponding document and thesis

Tools used in our researches: