Cognitive Radio-Based Vehicular Ad Hoc and Sensor Networks

Abstract

Current advancements in vehicular networking lead to amplifying the issue of spectrum scarcity. Cognitive radio (CR) has emerged as the key technology that enables flexible, efficient, and reliable spectrum exploiting by unlicensed networks to use licensed spectrum bands in an opportunistic manner to alleviate the spectrum scarcity issue. We have already proposed vehicular ad hoc and sensor networks (VASNET) as a new networking paradigm for vehicular communication by utilizing wireless sensor nodes in two mobile and stationary modes. The nodes are employed to sense vehicles' activity, for example, car crashes. Like other unlicensed networks, VASNET is supposed to operate over unlicensed spectrum bands. However, due to emergency nature of accident alarms in VASNET that must be received in minimum period of time and avoiding packet loss, in this paper we investigate CR-based VASNET, named as CR-VASNET. Various challenges and issues are discussed in details. In order to save stationary nodes' power and enlarge the network lifetime, an optimization technique for relay node selection is proposed. Furthermore, for primary users (PU) protection, an energy detection-based scheme is suggested to calculate the probability of PU arrival. Our theoretical discussions and simulation results proved the efficient functionality of the proposed CR-VASNET as a promising vehicular networking paradigm.

Single‐channel slotted contention in cognitive radio vehicular networks

“…Spectrum exploitation is to detect the presence or absence of the PU in the nominated channels. The authors of [11–13] introduced non‐cooperative modified energy detector sensing schemes. They developed energy detectors designed to operate in a low SNR, a dual‐step energy detector and a detector with an adaptive threshold value.…”

“…Thus motivated, several spectrum exploration and exploitation techniques have been developed in the CR‐VANET literature to, respectively, enable the vehicles to sense and report their channel assessments [6–23]. Typically, such techniques are incorporated with the IEEE 802.11p standard specifically developed for VANETs to enable DSA and CR.…”