An Experimental Vehicular Wireless System and Link Performance Analysis

Reliable wireless communication is a key component for intelligent transportation systems (ITS). This paper develops a wireless module for ITS using an AR7100 series embedding platform. The module consists of a low-cost multi-interface wireless mesh and control unit to provide high quality of services for different applications. It acts as a node in a vehicular wireless network with a pure software extension without costly hardware modifications. The developed system was tested in the urban area of the Wuhan city, China. It is observed that the fast fading effect plays a significant role in the performance of vehicular communications. To characterize these effects, a physical-level model of the radio link between two moving vehicles is proposed. This model takes the impacts of Rician K-factor, vehicle speed ratio, and Doppler spectrum into consideration. Compared with the existing physical models, the proposed physical-level model is shown to be more accurate in describing the packet-level characteristics of vehicle communications. Furthermore, the analysis of the proposed physical-level model indicates the necessity of cross-layer design of vehicular wireless networks.