降低MB-OFDM认知无线电带外干扰的编码调制方法及其性能分析
doi: 10.3724/SP.J.1146.2007.01897
Coded-modulation Scheme for Interferences Mitigation from MB-OFDM Cognitive Radio and Its Performance Analysis
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摘要: 该文针对降低多频带正交频分复用(MB-OFDM)认知无线电系统带外干扰的要求，利用数学推导的方法，得出带外干扰的表达式，提出了一种以两个、四个或多个子载波分组的编码调制方法。该方法增大了带外信号衰减速度，从而产生满足要求的频谱凹槽深度，有效地降低对周围无线业务的干扰，最终达到认知系统和其它窄带系统的共存。另外，理论分析和仿真结果表明该编码调制具有另一个优点：Rayleigh信道中，一定的信噪比下可以获得更好的误码率性能。Abstract: In order to satisfy the requirement of mitigating interferences caused by MB-OFDM cognitive radio systems, a type of coded-modulation scheme among two, four or several sub-carriers, is proposed, which is derived from side-lobe interference expressions. Based on this method, the side-lobe signal of MB-OFDM decreases quickly, and then the frequency notch, overlapping with other radio services, is deep enough. Consequently, interferences from cognitive radio systems is decreased, and the coexistence with other narrow band radio services is realized. In addition, theoretic analysis and simulation results show that the coded-modulation scheme has an additional merit: when SNR arrives at a certain value, compared with traditional modulation, much better Bit Error Rate (BER) performance can be achieved over Rayleigh fading channels.
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