  Cognitive radio (CR) is a promising technology to improve spectrum
utilization. However, spectrum availability is uncertain which mainly depends
on primary user's (PU's) behaviors. This makes it more difficult for most
existing CR routing protocols to achieve high throughput in multi-channel
cognitive radio networks (CRNs). Inter-session network coding and opportunistic
routing can leverage the broadcast nature of the wireless channel to improve
the performance for CRNs. In this paper we present a coding aware opportunistic
routing protocol for multi-channel CRNs, cognitive radio opportunistic routing
(CROR) protocol, which jointly considers the probability of successful spectrum
utilization, packet loss rate, and coding opportunities. We evaluate and
compare the proposed scheme against three other opportunistic routing protocols
with multichannel. It is shown that the CROR, by integrating opportunistic
routing with network coding, can obtain much better results, with respect to
throughput, the probability of PU-SU packet collision and spectrum utilization
efficiency.
