一种智能天线MC-CDMA系统中的最小二乘恒模波束成形算法

提出了智能天线多载波CDMA系统中一种最小二乘恒模波束成形算法，它是在对多载波阵列接收信号进行恒模波束成形的同时，用已估信道参数对各个子载波上的信号进行合并（采用ORC、EGC或MRC），然后对合并后的信号进行判决，用判决后的信息和期望用户的扩频码重构各个子载波上的信号，最后用此重构信号与波束成形输出信号的差去控制波束成形器的抽头系数，从而提高了系统的性能．对这种波束成形算法与传统的最小二乘恒模波束成形算法进行了仿真比较，仿真结果表明，提出的束成形算法的误码性能优于传统的算法．

An LSCM Beam-forming Algorithm in Smart Antenna MC-CDMA System

Multi-carrier CDMA combines the advantages of Orthogonal Frequency Division Multiplexing(OFDM) and CDMA,which means that the signal can be transmitted or received by the Inverse Discrete Fourier Transform(IDFT) or Discrete Fourier Transform(DFT) without increasing any more complexities of the transmitters and receivers.Due to its high efficiency of spectrum and robustness to the frequency selective channel,the multi-carrier CDMA is more suitable for broadband transmission and attracts more attention.MC-CDMA,MC-DS/CDMA and MT-CDMA are three kinds of transmission methods in multi-carrier CDMA system.Since the smart antenna technique can suppress MAI,enhance the performance and increase the capacity of the system efficiently,the MC-CDMA system based on smart antenna also attracts much attention.There are two beam-forming techniques,which are the uplink one and downlink one,but in this paper we focus on the former technique of the receiver in the smart antenna MC-CDMA system.And we propose a novel least squares constant modulus beam-forming algorithm in smart antenna MC-CDMA system. It adaptively beam-forms the multi-carrier antenna array signal using the LSCMA and in the meantime the beam-formed signal on every sub-carrier is combined by using ORC,EGC or MRC,and then the decision of the combined signal and the spread-code of the expected user are used to re-construct the signal on every sub-carrier,at last the difference between the re-constructed signal and the output signal of the beam-former is used to control the coefficients of the beam-former. We simulate and compare it with the conventional LSCM beam-forming algorithm.And the simulation results show that the proposed algorithm is superior to the latter.