Packet relay‐assisted V2V communication with sectorised relay station employing payload combining scheme

Abstract

A reliable vehicle-to-vehicle communication (V2VC) is essential to enable safe and highly automated driving system. Addition of a relay station (RS) can improve packet delivery rate (PDR) of CSMA/CA-based V2VC. However, the improvement is limited by packet collision at RS due to a hidden terminal (HT). This HT problem can be alleviated by employing sectorised receive antenna at RS, i.e. sectorised relay-assisted (SR-) V2VC. However, SR-V2VC still faces another problem, i.e. packet congestion at RS under high traffic conditions due to the improved packet reception rate. This leads to packet drop at RS and hence limits the improvement brought by SR-V2VC. Consequently, it is crucial to introduce a kind of traffic congestion avoidance methods to RS. In this article, the authors propose SR-V2VC with a payload combining forwarding (PCF) method (SR-V2VC/PCF) and theoretically evaluate the system performance using a CSMA/CA collision model. Large-scale computer simulations are also conducted to confirm the performance improvement brought by SR-V2VC/PCF. It is shown that the lowest broadcast PDR of 62% for the non-relay system is improved to higher than 81% by SR-V2VC/PCF and the directivity of the sector antenna has impact on the benefit of the proposed scheme.