Turbo Multicode Detection for Turbo-Coded HSDPA Systems

In this letter, a TIR (turbo iterative receiver) structure is proposed for the 3G HSDPA (high-speed downlink packet access) systems. The TIR performs two successive soft-output decisions, achieved by a SISO (soft-input soft-output) multicode detector and a SISO turbo decoder, through an iterative process. At each iteration, extrinsic information is extracted from detection and decoding stages and is then used as a priori information in the next iteration, just as in turbo decoding. A direct implementation of the SISO multicode detector has a prohibitive computational complexity. A low-complexity SISO multicode detector is developed by making use of soft multicode interference (MCI) cancellation technique. Computer simulations show that the TIR offers significant performance gain over the traditional receiver