Practical implementation of software reconfigurable multi-user detection for maximizing capacity and coverage of IMT-2000 DS-CDMA base stations

摘要

Without some form of interference cancellation, IMT-2000 wideband CDMA base stations are severely limited in both capacity and range by cochannel interference (CCI). The sector capacity may be limited to only 40 simultaneous voice users, and the radius of coverage may be limited to less than 1.8 Km. Researchers have developed digital signal processing (DSP) methods, including multi-user detection (MUD), which can double or triple the interference limited capacity. However, these computationally intensive methods have not been practical to implement previously, in commercial base stations. Lately, methods for implementing useful reduced-complexity multi-user detectors have been discovered. With the advances in DSP and crossbar technology, practical implementations of MUD can now be installed in third generation (3G) base-station transceivers (BTS). A single 6U-sized module can double the uplink capacity of a sector modem to a 100 or more users. Alternately, the can be increased by 150%. Simulation results of a multi-stage decision feedback (MDF) interference cancellation system, implemented on the module, are presented.