JOINT CHANNEL AND POWER ALLOCATION FOR COGNITIVE RADIO SYSTEMS WITH PHYSICAL LAYER NETWORK CODING

In this paper, we consider cognitive radio network in which two cognitive radio sourcescommunicate with two cognitive destinations via a relay node. The decode and forward (DF) relaynode employs physical layer network coding (PLNC) to improve the data rate. Based on theavailability of the spectrum bands at the source, relay and destination, the network employs threedifferent diversity schemes namely source to relay diversity, relay to destination diversity andcombination of earlier two diversity schemes with overall source to destination diversity schemes.The optimal allocation of channel and power with per band and sum power constraints of a node inthe network is formulated as convex optimization problem to improve the end to end throughput ofthe cognitive radio network. Simulation results show that the resultant joint channel and powerallocation are superior to the equal power allocation in terms of both end to end throughput andoutage probability.