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Efficient and reliable subcarrier power joint allocation is served as a promising problem in cognitive OFDM-based Cognitive Radio Networks (CRN). This paper focuses on optimal subcarrier allocation for OFDM-based CRN. We mainly propose subcarrier allocation scheme denoted as Worst Subcarrier Avoiding Water-filling (WSAW), which is based on Rate Adaptive (RA) criterion and three constraints are considered in CRN. The algorithm divides the assignment procedure into two phases. The first phase is an initial subcarrier allocation based on the idea of avoiding selecting the worst subcarrier in order to maximize the transmission rate; while the second phase is an iterative adjustment process which is realized by swapping pairs of subcarriers between arbitrary users. The proposed scheme could assign subcarriers in accordance with channel coherence time. Hence, real time subcarrier allocation could be implemented. Simulation results show that, comparing with the similar existing algorithms, the proposed scheme could achieve larger capacity and a near-optimal BER performance.
Efficient and reliable subcarrier power joint allocation is served as a promising problem in cognitive OFDM-based Cognitive Radio Networks (CRN). This paper focuses on optimal subcarrier allocation for OFDM-based CRN. We primarily propose subcarrier allocation scheme denoted as Worst Subcarrier Avoiding Water -filling (WSAW), which is based on Rate Adaptive (RA) criterion and three constraints are considered in CRN. The first phase is an initial subcarrier allocation based on the idea of avoiding selecting the while subcarrier in accordance with the channel coherence time; therefore the real time subcarrier allocation could be implemented. Simulation results show that, comparing with the similar existing algorithms, th e proposed scheme could achieve larger capacity and a near-optimal BER performance.