多载波CDMA系统中联合检测译码方法研究

Study of Joint Detection and Decoding in Multi-Carrier CDMA

为了提高多载波CDMA(MC CDMA)系统的抗干扰能力与系统容量 ,提出了一种将信道参数检测与纠错码译码联合运算进行的方法 ,得到了一种反馈级联结构 .在分析MC CDMA系统接收性能时 ,通常假设信道参数能精确估计 ,但对于时变信道在实现上是困难的 ;根据本文提出的级联结构 ,先用导频符号进行信道参数估计 ,再用导频符号的译码信息作为导频符号进行信道参数的进一步优化 ,构成一种联合检测译码结构 ,能有效地降低导频符号数量 ,并提高了信道参数估计精度 .通过仿真 ,与传统的方法进行了性能比较 ,联合检测译码方案能获得较大系统增益 ,是一种优化方案 .

To suppress the interference and improve capacity of multi-carrier CDMA (MC-CDMA), a new method of joint detection and decoding is proposed. Also, a new feedback concatenated structure is obtained. Current researches on the performance of the MC-CDMA detectors made the assumption that the multiplicative complex channel coefficients are perfectly known in the receiver, which is impractical in the engineering. Channel is firstly estimated with the aid of pilot symbol. It is then optimized by feedback decoding data. With the scheme, channel can be estimated precisely without long pilot symbols. Simulation results show that the performance of joint detection and decoding is much better than traditional concatenated structure. Thus, our proposed scheme is an optimal detection method.