Distributed optimization of a multisubchannel Ad Hoc cognitive radio network
KAUST DepartmentElectrical Engineering Program
Physical Sciences and Engineering (PSE) Division
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Communication Theory Lab
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AbstractIn this paper, we study the distributed-duality-based optimization of a multisubchannel ad hoc cognitive radio network (CRN) that coexists with a multicell primary radio network (PRN). For radio resource allocation in multiuser orthogonal frequency-division multiplexing (MU-OFDM) systems, the orthogonal-access-based exclusive subchannel assignment (ESA) technique has been a popular method, but it is suboptimal in ad hoc networks, because nonorthogonal access between multiple secondary-user links by using shared subchannel assignment (SSA) can bring a higher weighted sum rate. We utilize the Lagrangian dual composition tool and design low-complexity near-optimal SSA resource allocation methods, assuming practical discrete-rate modulation and that the CRN-to-PRN interference constraint has to strictly be satisfied. However, available SSA methods for CRNs are either suboptimal or involve high complexity and suffer from slow convergence. To address this problem, we design fast-convergence SSA duality schemes and introduce several novel methods to increase the speed of convergence and to satisfy various system constraints with low complexity. For practical implementation in ad hoc CRNs, we design distributed-duality schemes that involve only a small number of CRN local information exchanges for dual update. The effects of many system parameters are presented through simulation results, which show that the near-optimal SSA duality scheme can perform significantly better than the suboptimal ESA duality and SSA-iterative waterfilling schemes and that the performance loss of the distributed schemes is small, compared with their centralized counterparts. © 2012 IEEE.
SponsorsThis work was supported in part by the Ministry of Knowledge Economy, Korea, through the Information Technology Research Center Support Program supervised by the National IT Promotion Agency (NIPA) under Grant NIPA-2012-(C1090-1211-0005), the Ministry of Education, Science and Technology of the Republic through the National Research Foundation of Korea under Grant 2011-0029329, and Qatar National Research Fund (a member of Qatar Foundation). This paper was presented in part at the IEEE International Global Communications Conference, December 2009 and 2010. The review of this paper was coordinated by Prof. W. A. Hamouda.