Analysis of slotted CDMA packet access based on non-linear multiuser detection

In this paper, we assess the impact of layered spacetime detection technique, known as V-BLAST, for multiuser detection over a packetized random access system based on CDMA and Slotted ALOHA. In this scheme, the multiple transmit antennas are treated as individual packet radio mobile stations, while the base station consists of multiple receive antennas. In addition, users are arranged in groups and allocated the same group signature sequence. The spreading technique is hence used to separate between the groups, and the layered space-time algorithm is then invoked to detect the signals from all users transmitting packets at the same time. A significant improvement in system throughput, delay and capacity are achieved.