Wireless Mesh Networks for Intelligent Transportation Systems

The wireless mesh network (WMN) is an economical solution for disseminating broadband wireless information in the intelligent transportation systems (ITS). This paper investigates the issue of deploying access points (APs) in an ITS wireless mesh network, where several adjacent APs form a cluster. Each AP in a cluster operates as a wireless relay to forward neighboring AP´s traffic to the central access point connected to the Internet through cables. In general, access points are placed for maximizing cell coverage. However, larger coverage of an AP leads to lower throughput and longer delay in the access link as well as in the relay link. To find the optimal tradeoffs among delay, capacity, and coverage, we develop a physical (PHY)/medium access control (MAC) cross-layer analytical model to evaluate the throughput and delay of the considered ITS wireless mesh network. We consider the carrier sense multiple access (CSMA) protocol and the impact of hop distance on the data rate in the physical layer. Then, we apply the mixed-integer nonlinear programming (MINLP) optimization approach to determine the optimal number of APs in a cluster and the best cell radius of each AP, aiming at maximizing the capacity and coverage of a cluster of APs subject to the delay and fairness requirements.