Improving vehicular safety message delivery through the implementation of a cognitive vehicular network

Keywords: WAVE Cognitive radio networks Safety applications Spectrum management a b s t r a c t The Wireless Access in Vehicular Environments (WAVE) protocol stack has been recently defined to enable vehicular communication on the Dedicated Short Range Communication (DSRC) frequencies. Some recent studies have demonstrated that the WAVE technology might not provide sufficient spectrum for reliable exchange of safety information over congested urban scenarios. In this paper, we address this issue, and present a novel cognitive network architecture in order to dynamically extend the Control Channel (CCH) used by vehicles to transmit safety-related information. To this aim, we propose a cooperative spectrum sensing scheme, through which vehicles can detect available spectrum resources on the 5.8 GHz ISM band along their path, and forward the data to a fixed infrastructure known as Road Side Units (RSUs). We design a novel Fuzzy-Logic based spectrum allocation algorithm, through which the RSUs infer the actual CCH contention conditions, and dynamically extend the CCH bandwidth in network congestion scenarios, by using the vacant frequencies detected by the sensing module. The simulation results reveal the effectiveness of our architecture in providing dynamic and scalable allocation of spectrum resources, and in increasing the performance of safety-related applications. In these last years, wireless systems and technologies for vehicular communication have attracted significant research interests from government, industry, and academia throughout the world. One of the reason of this interest is constituted by the plethora of novel applications and services that can be developed in a vehicular environment, ranging from safety-related systems, collision-avoidance applications, and traffic-monitoring systems to emerging vehicle-to-vehicle communication and multimedia streaming applications, just to cite a few. Due to the high requests of bandwidth needed to support these applications , specific portions of the spectrum have been reserved to enable vehicle-to-vehicle and vehicle-to-infrastructure communication, in both the US and Europe. For instance, the U.S. Federal Communication Commission (FCC) has allocated 75 MHz of Dedicated Short Range Communications (DSRC) spectrum at 5.9 GHz to be used exclusively for vehicle-to-vehicle and infrastructure-to-vehicle communications. The DSRC spectrum is divided into 7 channels with a 10 MHz bandwidth allocated to each one. Six out of these channels are Service Channels (SCH) while the center one is the Control Channel (CCH). The spectrum allocation has been followed by continuous efforts to standardize the entire protocol stack used by vehicular communication. A new amendment protocol of the 802.11 family, i.e., …