Adaptive subcarrier bandwidth and power in OFDM-based cognitive radio systems for high mobility applications

作者：He, Jian^*; Xu, Changqing; Li, Li

来源：International Journal of Communication Systems, 2014, 27(10): 1626-1636.

DOI：10.1002/dac.2424

• orthogonal frequency division multiplexing (OFDM)
• cognitive radio
• Doppler frequency spread
• intercarrier interference (ICI)
• adaptive subcarrier bandwidth
• joint optimization

OFDM-based cognitive radio systems are spectrally flexible and efficient, but they are vulnerable to intercarrier interference (ICI), especially in high mobility environments. High mobility of the terminal causes large Doppler frequency spread resulting in serious ICI. Such ICI severely degrades the system performance, which is ignored in the existing resource allocation of OFDM-based cognitive radio systems. In this paper, an adaptive subcarrier bandwidth along with power allocation problem in OFDM-based cognitive radio systems for high mobility applications is investigated. This adaptive subcarrier bandwidth method should choose the suitable subcarrier bandwidth not only to balance the tradeoff between ICI and intersymbol interference but also to be large enough to tolerate an amount of Doppler frequency spread but less than the coherence bandwidth. The power budget and interference to primary users caused by cognitive radio users are imposed for primary users' protection. With these constraints, a joint optimization algorithm of subcarrier bandwidth and power allocation is proposed to maximize the bandwidth efficiency of OFDM-based cognitive radio systems in such conditions. Numerical simulation results show that the proposed algorithm could maximize the system bandwidth efficiency and balance this tradeoff while satisfying the constraints.

• 出版日期2014-10
• 单位上海交通大学