Multi-User Detection Techniques In DS-CDMA Communication Systems

The capacity and performance of direct sequence code division multiple access (DS-CDMA) is essentially dominated by multiple access interference (MAI). MAI is not caused by CDMA system itself, but by the traditional single user receiver strategy used in CDMA system. Multi-user detection (MUD) technique can alleviate or even eliminate MAI radically, so it improves system performance and enhances system capacity. On the basis of existing typical algorithms on multi-user detection in CDMA systems, serial-parallel interference cancellation and parallel-serial interference cancellation two new algorithms are proposed and analyzed. Both the two algorithms combine the basic idea of successive interference cancellation (SIC) and parallel interference cancellation (PIC) algorithm. The performance of the new detectors is analyzed and researched in detail in the paper.Theory analysis and simulation result show that two new algorithms have such advantages as a shorter processing time delay compared with SIC algorithm and simpler structure compared with PIC algorithm. The new algorithms also improve the bit error rate performance of SIC when the system has perfect power control and the bit error rate performance of PIC when no perfect power control technique is used in the system. The two new algorithms also have reasonable complexity.