Multistage detection of DS-CDMA signals with threshold level comparisons

Multiuser detection has been extensively researched as a method of decreasing the interference that occurs when many users simultaneously transmit in a direct sequence code division multiple access (DS-CDMA) system. The multistage detector attempts to estimate the interference that each user causes to every other user. The interference estimate is subtracted from all other signals. This method is computationally complex when there are many users present on the channel. In this paper we propose a multistage detector which only attempts to eliminate the multiple access interference (MAI) from a user´s signal if the decision variable falls below a certain threshold level. It is shown that this reduces the computational complexity and improves bit error rate performance compared to the conventional multistage detector