Distributed TDMA based MAC protocol for data dissemination in ad-hoc Cognitive Radio networks

Cognitive Radio (CR) seems to be a promising solution to radio spectrum overcrowding problem. Cognitive Radio Network (CRN) allows opportunistic uses of spectrum holes by enabling the coexistence of licensed (primary) users and unlicensed (secondary) users. Data dissemination in a CRN is very useful to propagate non-urgent messages in order to limit cost and complexity of the network. MAC protocols in existing legacy wireless networks do not support the coexistence of licensed and secondary users. This limits the productive utilization of spectrum holes by secondary users. In this paper, we propose a distributed TDMA based MAC protocol for data dissemination in multi-hop ad-hoc CRNs. Our protocol aims at not only ensuring highest message reachability but also avoiding collision among secondary users. It classifies the set of available channels based on both primary radio unoccupancy and number of cognitive radio neighbours having the channel in their available channel set. The secondary users prepare a TDMA schedule using a distributed approach. Secondary users select the best channel from the available channel set using a channel selection strategy. This increases data dissemination reliability in multi-hop ad-hoc CRNs. Simulation results show the efficacy of proposed method.