A Multiuser Detector for TD-SCDMA Systems based on the Bareiss Algorithm

In time slotted CDMA systems with an antenna array at the base station, multiuser detection (MUD) algorithms exploit space-time (ST) techniques to alleviate both multiple access and inter-symbol interference. Linear ST-MUD algorithms solve a linear problem by inverting the system matrix that has block-Toeplitz shape. Exact inversion methods are not practically used since they impose an unacceptable computational load due to the large number of concurrent users, antenna array elements and transmitted data symbols. Therefore, in real-world cases, sub-optimal algorithms with reduced complexity are mandatory to reduce the high computational processing power required. However, when computational complexity is reduced, sub-optimal algorithms introduce performance degradation and near-far effects. The block-Fourier algorithm is generally considered the most effective ST-MUD detector for its simple design combined with good overall performances. However, it presents serious near-far effects and limited BER performances when real-world mobile radio systems are considered. Recently, the author has introduced a novel block ST-MUD scheme that uses the block-Bareiss algorithm (BB). In this paper, the BB detector is analyzed in details and its performance vs. complexity figures are compared with other known MUD techniques. The BB detector shows good performances and low computational power requirements without suffering from near-far effects. In addition, it compares favorably with respect to the simpler hardware design based on low order block-Fourier algorithms. Simulations and hardware feasibility issues are presented and discussed for the specific CWTS (Chinese Wireless Telecommunication Standard) application.