A framework for reliable and timely communications in VANETs

Abstract

Recent technological developments have resulted in the extensive usage of Vehicular Ad‐hocNetworks (VANET) for Intelligent Transport Systems (ITS) and road safety applications. With aroad safety application, vehicles in a VANET are required to consistently communicate with itsneighbours and exchange the information about their position and other specific road safetydata. Realising this service of road safety from VANET requires the need of reliable delivery ofthe emergency information about road accidents in timely manner. However, supporting bothtimely and reliable delivery of the data messages (emergency information) to the receiver hasbecome highly challenging in VANET because of the factors like vehicle mobility, dynamicmobility pattern of the vehicles, dynamic network topology, and error‐prone wirelesscommunication channel. Moreover, practical application of VANETs in the road safetyapplications requires the need of sharing the channel media so that reliable and timely deliveryof the data can be supported. In this research, the effectiveness of the error control methodis explored and a novel approach of Adaptive Byte‐level HARQ (Hybrid Automatic RepeatRequest) (AB‐HARQ) was developed to guarantee reliable delivery of the messages to thedestination. Despite the evaluations showing is high probability of success in delivering thesafety messages, the extent of overhead involved in this method is found to be high.Identifying this room of improvement available for the proposed approach, a novel MACschemecalled Broadcasting Relayed‐based Cross‐layer Medium Access Control (BRC‐MAC) isdeveloped in this research. This BRC‐MAC explores the effectiveness of Network Coding (NC)method in assuring reliable delivery of the safety messages without any extra overhead.Analytical model of this BRC‐MAC showed the error recoverability and the high probability ofdelivering the safety messages within the deadline to the destination. From this analyticalmodel of BRC‐MAC, a criteria function F􀭰􀭴 􁈺i􁈻 was developed to help in selecting the relayvehicle to support both reliable and timely communication of the safety messages. In additionto this analytical model, the effectiveness of the proposed BRC‐MAC method is also evaluatedin this research through simulation studies. The simulation results of BRC‐MAC showed theability of this novel MAC method in terms of the probability of successful packet delivery,packet delay and the network throughput. Finally, considering the high extent of theoccurrence of hidden node problem in the wireless networks, an improved three‐way handshakemethod to exchange data is given in this report and then evaluated by combining with3the BRC‐MAC method. Therefore, both theoretical analysis and simulation studies were usedin this thesis to evaluate the performance of the proposed MAC scheme.

Date of Award	12 Mar 2017
Original language	English
Awarding Institution	University of Bedfordshire
Supervisor	Sijing Zhang (Supervisor) & Enjie Liu (Second supervisor)