We consider a cognitive radio network consisting of a primary cellular systemand a secondary cognitive machine-to-machine (M2M) system, and study thethroughput enhancement problem of the latter system employinguniversal-filtered orthogonal frequency division multiplexing (UF-OFDM)modulation. The downlink transmission capacity of the cognitive M2M system isthereby maximized, while keeping the interference introduced to the primaryusers (PUs) below the pre-specified threshold, under total transmit powerbudget of the secondary base station (SBS). The performance of UF-OFDM based CRsystem is compared to the performances of OFDM-based and filter bankmulticarrier (FBMC)-based CR systems. We also propose a near-optimal resourceallocation method separating the subband and power allocation. The solution isless complex compared to optimization of the original combinatorial problem. Wepresent numerical results that show that for given interference thresholds ofthe PUs and maximum transmit power limit of the SBS, the UF-OFDM based CRsystem exhibits intermediary performance in terms of achievable capacitycompared to OFDM and FBMC-based CR systems. Interestingly, for a certain degreeof robustness of the PUs, the UF-OFDM performs equally well as FBMC.Furthermore, the percentage rate-gain of UF-OFDM based CR system increases by alarge amount when UF-OFDM modulation with lower sidelobes ripple is employed.Numerical results also show that the proposed throughput enhancing methoddespite having lower computational complexity compared to the optimal solutionachieves near-optimal performance.
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