In non-contiguous orthogonal frequency-division multiplexing (NC-OFDM)based cognitive radio sys-tems,conventional active interference cancellation (AIC)and extended AIC (EAIC)schemes use the same rectangular waveform of the same length for all canceling carriers (CCs),leading to the limitation of performance improvement of side-lobe suppression or inter-carrier interference (ICI)reduction.In this paper,a novel variable cancellation basis was proposed for side-lobe suppression in NC-OFDM cognitive radio systems based on the observation that CCs in different frequency have non-uniform attribution for sidelobe suppression.So,CCs are grouped by frequency locations and shaped with different waveforms of different lengths to satisfy good side-lobe suppression performance while reducing ICI at the same time.Nu-merical results show that,with the proposed CC scheme,NC-OFDM signal’s side-lobe can be suppressed to -60 dB with negligible signal-to-noise ratio loss at a symbol error rate of 1 0 -5 with 64 quadratic-amplitude modulation symbol.%在抑制非连续载波正交频分复用（Non-contiguous Orthogonal Frequency-Division Multiplexing，NC-OFDM）系统旁瓣的方法中，使用固定长度和矩形形状干扰抵消子载波的主动干扰抵消方法（Active Interference Cancellation， AIC）抑制深度不够，而其改进方法扩展 AIC （Extended AIC）对数据子载波干扰又太大。本文发现插入在不同频段的干扰抵消子载波对旁瓣抑制的效果不同，并在此基础上提出对干扰抵消子载波按频率分组，不同组的干扰抵消子载波使用不同的长度与波形，从而提高对 NC-OFDM信号旁瓣的抑制效果，同时减小了所引入的载波间干扰。仿真结果表明：采用本文提出的可变基函数方案，在达到－60dB 的旁瓣抑制深度时，即使采用高阶的64-QAM符号映射（实验条件是误符号率为10－5），干扰抵消信号对数据子载波造成的载波间干扰也几乎可以忽略。
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