多径衰落信道下的扩频码设计与联合检测

在多径衰落信道CDMA系统中，扩频码设计与联合检测为提高系统容量的两个重要手段。在扩频码设计中，通过构造零相关窗码可以消除MAI和ISI，从而提高系统容量。当扩频码相关特性不理想时，通过联合检测也可以消除干扰，提高系统容量。但二者都有一定局限性，对于零相关窗码来说，它的码字资源十分有限，对于联合检测来说，当用户数很大，它的复杂度不能容忍。该文将扩频码设计与联合检测结合起来，提出了一种具有组间零相关窗特性的新型扩频码。在扩频码设计时考虑联合检测，可以增加码字资源，在联合检测中考虑扩频设计，又可以降低联合检测的复杂度。

Spreading code design and joint detection in multi-path fading channels

Spreading code design and joint detection are two efficient ways to increase CDMA system capacity in multi-path fading channels. In spreading code design, MAI and ISI are removed by constructing spreading codes with zero correlation window, which increases system capacity. Joint detection can also eliminate MAI and ISI when the cross-correlation of spreading codes is imperfect. However, the code resource is very limited for ZCW spreading codes and the complexity of joint detection is huge when the number of code channels takes large. A novel spreading code with group-wise zero correlation window is proposed in this paper by combining the spreading code design and joint detection. More code resource is obtained by introducing joint detection in the spreading code design, and the complexity is reduced by introducing spreading code design in the joint detection.