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This paper is concerned with the resource allocation for multiple input multiple output and orthogonal frequency division multiplexing access(MIMO-OFDMA)downlink cognitive radio systems where a cognitive radio MIMO-OFDMA system is under spectrum sharing with an existing primary radio(PR)network.We use the channel learning scheme to estimate the channel information from cognitive radio transmitter(CR-TX)to PR and then make beamforming to transmit signal.Considering the interference from CR-TX to PR caused by the imperfect channel learning,we intend to maximize CR throughput under the interference power constraint at PR and CR transmit power constraint.A nearly optimal subcarrier and power allocation algorithm with linear complexity is proposed.The proposed algorithm is global optimal when the maximum transmit power is beyond certain threshold.Simulation results show that the proposed algorithm has a good performance very close to the global optimal algorithm.
This paper is concerned with the resource allocation for multiple input multiple output and orthogonal frequency division multiplexing access (MIMO-OFDMA) downlink cognitive radio systems where a cognitive radio MIMO-OFDMA system is under spectrum sharing with an existing primary radio (PR) network. We use the channel learning scheme to estimate the channel information from cognitive radio transmitter (CR-TX) to PR and then make beamforming to transmit signal. Consongring the interference from CR-TX to PR caused by the imperfect channel learning, we intend to maximize CR throughput under the interference power constraint at PR and CR transmit power constraint. A nearly optimal subcarrier and power allocation algorithm with linear complexity is proposed. The proposed algorithm is global optimal when the maximum transmit power is beyond certain threshold. Simulation results show that the proposed algorithm has a good performance very close to the global optimal algorithm.