Primary user localisation and uplink resource allocation in orthogonal frequency division multiple access cognitive radio systems

In cognitive radio networks, secondary users (SUs) can share spectrum with primary users (PUs) under the condition that no interference is caused to the PUs. To evaluate the interference imposed to the PUs, the cognitive systems discussed in the literature usually assume that the channel state information (CSI) of the link from a secondary transmitter to a primary receiver (interference link) is known at the secondary transmitter. However, this assumption may often be impractical in cognitive radio systems, since the PUs need to be oblivious to the presence of the SUs. The authors first discuss PU localisation and then introduce an uplink resource allocation algorithm for orthogonal frequency division multiple access-based cognitive radio systems, where relative location information between primary and SUs is used instead of CSI of the interference link to estimate the interference. Numerical and simulation results show that it is indeed effective to use location information as a part of resource allocation and thus a near-optimal capacity is achieved.This work is an extended version of the paper presented in Conference on Cognitive Radio Oriented Wireless Networks and Communications (CrownCom), Cannes, France, June 2010. The work of M. -S. Alouini was supported by the Qatar National Research Fund (a member of Qatar Foundation) under NPRP Grant NPRP 5-250-2-087. The statements made herein are solely the responsibility of the authors. The work of H. Nam was supported by the MSIP (Ministry of Science, ICT and Future Planning), Korea, under ICT/SW Creative Research Program (NIPA-2014-H0509-14-1003) supervised by the NIPA (National IT Industry Promotion Agency)