Complementary Coded Identical Code Cyclic Shifted Multiple Access and Its Performance Analysis

The scarcity of available spreading codes poses a hard limitation to user capacity for a code-division multiple access system. In previous work by Liu
et al.
(2020), the identical code cyclic shift multiple access (ICCSMA) scheme was developed, which allows multiple users to share one spreading code. However, the ICCSMA system uses the basic
$m$
-sequence as the prime code to generate the identical code cyclic shift code, which has a nonideal correlation property and produces a considerable interference in a frequency-selective fading channel. To address this issue, we suggest using the complementary code (CC), which exhibits the perfect correlation property, to suppress the interference, and the proposed scheme is named CC-ICCSMA. Different from the article by Liu
et al.
(2020), a 3-D transceiver is designed in this article, and the CC set is employed to perform the multiple user detection. The simulation results demonstrate that the CC-ICCSMA strategy achieves a much better bit error rate performance than
$m$
-sequence-based ICCSMA in the frequency-selective fading channels. Also, the outstanding anti-interference capability of CC-ICCSMA can help improve user capacity.