A new chip-level linear BSOR-GSIC multi-user detector for long-code CDMA systems

In this work, a new chip-level linear group-wise SIC (GSIC) multi-user scheme that is asymptotically equivalent to the block successive over-relaxation (BSOR) iteration (known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed) is proposed. The proposed scheme directly uses the spreading codes and doesn't require the calculation of the cross-correlation matrix of the spreading codes, which results in a considerable reduction in computational complexity. Hence, it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We determine the condition of convergence of the proposed scheme using two different approaches and prove that it converges to the decorrelator detector if the over-relaxation factor is within the interval (0, 2). Simulation results are in excellent agreement with theory.