Energy-efficient broadcast in multihop cognitive radio networks

Broadcast is an important operation in Cognitive Radio Networks (CRNs). How to achieve broadcast in an energy-efficient way is important since users in CRNs are usually battery-powered. Existing single-channel broadcast mechanisms are not suitable for CRNs because multiple channels can be used in a CRN. Most existing multi-channel broadcast schemes rely on a common control channel (CCC) to support broadcast. However, finding such a CCC in a CRN is difficult because an unlicensed user’s available channels are changed over time and space. In this paper, we focus on an environment where no broadcast structure or CCC is established in advance while a node is equipped with one CR transceiver and does not aware of the locations and distances to other nodes. We have defined the one-hop Minimum Multichannel Set Cover (MMSC) problem and the multi-hop Minimum Cost Broadcast (MCB) problem in such an environment. Both problems are NP-hard and we have proposed a heuristic solution, the Energy-Efficient Broadcast (EEB) protocol, to solve them. Considering the uncertain primary user occupancy issue, the EEB protocol features a distributed solution that uses only local information. Simulation results verify that EEB effectively reduces energy consumption and achieves high packet delivery ratio.