RLS de-spread re-spread multitarget array algorithm for MC-CDMA
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摘要: 多载波码分多址(MC-CDMA)系统是将OFDM技术与CDMA技术结合起来的一种综合技术.MC-CDMA系统中同信道干扰仍然是影响系统性能的主要因素,这就需要使用智能天线来提高系统的性能.介绍一种适用于MC-CDMA系统的自适应阵的盲算法递推最小二乘解扩重扩多目标阵列(RLS-DRMTA)算法,利用扩频码的信息进行波束形成,不需要训练序列,节约了频谱资源;与LS-DRMTA算法相比,RLS-DRMTA算法节省了运算时间;另外仿真表明在正交频分复用(OFDM)解调后进行波束形成,提高了系统的性能;为了降低系统的复杂度,还用到了载波分组技术,但分组技术又会降低系统的性能,所以分组时考虑了系统性能和运算速度的折衷.仿真结果表明RLS-DRMTA算法能使方向图的主波束对准信号方向,而在干扰方向形成零陷,从而达到抑制干扰的目的.Abstract: Multi-carrier code division multiple access(MC-CDMA) is a hybrid of orthogonal frequency division multiplexing(OFDM)and code division multiple access(CDMA).To resist co-interference of MC-CDMA system,smart antenna are used in MC-CDMA. A blind adaptive array algorithm was developed for MC-CDMA system by using recursive least-squares dispread respread multitarget array. The proposed algorithm without training sequence for adaptive beamforming doesn't waste extra-spectrum by utilizing information of CDMA spreading codes. Compared with the RLS-DRMTA,the extended RLS-DRMTA algorithm proposed is less computation-consuming. The high performance of the system is achieved by post-FFT beamforming. Subcarrier clustering is applied to reduce the complexity. But subcarrier clustering reduce the performance of the system .So the complexity and the performance of the system are considered in clustering subcarrier. The results of simulations can be shown by the RLS-DRMTA algorithm that the array focuses energy in the required direction,which helps to reduce the interference.
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