Power Allocation And Relay Selection Algorithm In Cooperative Cognitive Radio Networks

Cognitive radio, is unanimously regarded as the key technology to solve the problemof spectrum scarcity and low efficiency of spectrum use. With the deepening of theresearch of cognitive radio, scholars gradually find that resource allocation in cognitiveradio networks is vital but difficult to research. In order to increase the efficiency ofprocessing information, the cooperation communication has been introduced intocognitive radio networks.In this paper, we firstly introduce the background of cognitive radio and ad hocnetwork, the development of cooperative communications, also we analyze thebackground of cooperative communication technology used in cognitive radio system, inorder to pave the way for research in cooperative cognitive radio communication systemlater. Next, we base on FreeSpace model, describe and model the cooperative cognitiveradio network. In the cognitive model, we take full account of the limitation on secondaryusers, including battery capacity of the source node and relay, the interference with theprimary users to protect the primary users, the basic communication requirement ofcognitive radio network, and the QoS (Quality of Service) guarantees of some specificapplications. Then, aiming to maximize the system throughput, we present the OSA, thisalgorithm allocates the power of the system, and decides the optimal transmit power of thesource and the relay, selects the optimal relay, and determines the optimal relay selectionscheme finally. For the OSA with high complexity, so we also present an approximate butlow complexity algorithm AOSA. The AOSA assumes that the source just limits by theprimary users and not considers the battery capacity, so it simplifies the system model. Atlast, we simulate the model and the algorithms in this paper. Compare the optimalallocation approach OSA to random power allocation scheme and average powerallocation scheme, we can see that the OSA algorithm can increase the system totalthroughput, improve the relay selection scheme and decrease the packet-drop rate of thesystem obviously.