Resource Allocation for MDC Multicast in CRNs with Imperfect Spectrum Sensing and Channel Feedback

Shengyu LI  Wenjun XU  Zhihui LIU  Kai NIU  Jiaru LIN  

IEICE TRANSACTIONS on Communications   Vol.E98-B   No.2   pp.335-343
Publication Date: 2015/02/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.335
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
MDC multicast,  cognitive radio,  imperfect spectrum sensing,  imperfect channel feedback,  Gaussian approximation,  two-stage resource allocation,  

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In this paper, resource-efficient multiple description coding (MDC) multicast is investigated in cognitive radio networks with the consideration of imperfect spectrum sensing and imperfect channel feedback. Our objective is to maximize the system goodput, which is defined as the total successfully received data rate of all multicast users, while guaranteeing the maximum transmit power budget and the maximum average received interference constraint. Owing to the uncertainty of the spectrum state and the non-closed-form expression of the objective function, it is difficult to solve the problem directly. To circumvent this problem, a pretreatment is performed, in which we first estimate the real spectrum state of primary users and then propose a Gaussian approximation for the probability density functions of transmission channel gains to simplify the computation of the objective function. Thereafter, a two-stage resource allocation algorithm is presented to accomplish the subcarrier assignment, the optimal transmit channel gain to interference plus noise ratio (T-CINR) setting, and the transmit power allocation separately. Simulation results show that the proposed scheme is able to offset more than 80% of the performance loss caused by imperfect channel feedback when the feedback error is not high, while keeping the average interference on primary users below the prescribed threshold.