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Interference alignment (IA) can effectively eliminate the interference among users in cognitive radio (CR) networks. Nevertheless, to further increase the transmission rate of the primary user (PU) and guarantee its priority, we propose an optimal transceiver design (OTD) scheme for IA-based CR networks in this letter. In the OTD scheme, two partial-IA based algorithms are proposed to design the precoding matrices of SUs, in which the interference is aligned at the primary receiver with much lower overhead and complexity. Then the PU's precoding matrix is designed to maximize its throughput accordingly. To further improve the performance of SUs, their decoding matrices are re-designed. Simulation results are presented to show the effectiveness of the proposed scheme.Index Terms-Cognitive radio, interference alignment, quality of service, rayleigh quotient, spectrum sharing.

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ABSTRACT:The return waveform of satellite laser altimeter plays vital role in the satellite parameters designation, data processing and application. In this paper, a method of refined full waveform simulation is proposed based on the reflectivity of the ground target, the true emission waveform and the Laser Profile Array (LPA). The ICESat/GLAS data is used as the validation data. Finally, we evaluated the simulation accuracy with the correlation coefficient. It was found that the accuracy of echo simulation could be significantly improved by considering the reflectivity of the ground target and the emission waveform. However, the laser intensity distribution recorded by the LPA has little effect on the echo simulation accuracy when compared with the distribution of the simulated laser energy. At last, we proposed a refinement idea by analyzing the experimental results, in the hope of providing references for the waveform data simulation and processing of GF-7 satellite in the future.