Complexity-Reduced Per-Antenna Multiple Access Interference Cancellation for DAN Using DS-CDMA

DS-CDMA allows all accessing users to share the same carrier frequency and hence, can alleviate the sophisticated channel management problem. Recently, we investigated a distributed antenna network (DAN) using direct-sequence code division multiple access (DS-CDMA) with joint antenna diversity and equalization and showed that DAN achieves higher uplink capacity than centralized antenna network (CAN). The uplink capacity is limited due to multiple access interference (MAI). In this paper, to further improve the uplink capacity, we propose a complexity-reduced per-antenna MAI cancellation before diversity combining, which is suitable for DAN using DS-CDMA. In the per-antenna MAI cancellation, first, interfering users on each antenna are sorted in descending order of the instantaneous received power. Then, a predetermined number of interfering users having the highest received powers are selected on each antenna to be cancelled in the frequency-domain before diversity combining. It is shown by computer simulation that per-antenna MAI cancellation before diversity combining achieves almost the same uplink capacity as full MAI cancellation after diversity combining.