1Faculty of Graduate Studies
Department of Electrical Engineering
Islamic Azad University (IAU), Tehran south branch
2School of Electrical Engineering Iran University of Science and Technology (IUST) Narmak,Tehran, Iran.
3Shahid Rajaee Teacher Training University
This paper presents a simple relay selection algorithm in multiuser orthogonal frequency-division multiplexing (MU-OFDM) cooperative Cognitive Radio (CR) networks to enhance normalized sum capacity of secondary users (SUs). After simplifying three node relay network to its equivalent two node network with equivalent gain on each subcarrier, a simple method for relay selection is used which considers interference on primary users. In addition simple relay selection algorithm proposed. This simple algorithm selects the relay-node for each source-node by a fixed power allocation on all subcarriers (SCs) in independent phase before joint subcarrier and power allocation algorithm are performed. Simulation results demonstrate that this relay selection algorithm can significantly enhance normalized sum capacity of SUs compared to random relay selection algorithm.
cognitive radio (CR), cooperative communication, multiuser orthogonal frequency-division multiplexing (MU-OFDM), peak power constraint, relay selection, resource allocation