Efficient Interference Cancellation Algorithms for CDMA Utilizing Interference Suppression and Multipath Combining

摘要

A new, low rank adaptive algorithm that performs serial and parallel interference cancellation for a DS-CDMA in frequency selective multipath is presented. The algorithm provides interference suppression (IS) in place of matched filtering at each stage of the cancellation for better interference mitigation. It employs a computationally efficient, correlation-subtraction architecture (CSA) based on the multistage Wiener filter (MWF) to do the IS at each successive stage. This CSA-MWF structure meets MMSE performance but requires substantially fewer computations than the MMSE receiver, and eliminates the need for matrix inversion, eigen-decomposition, or the construction of blocking matrices. Embedded within the new structure is also a RAKE receiver that combines the multipath components for added performance gain. It is shown that this technique performs significantly better than the conventional matched filter (MF) SIC. The performance gains of the joint MWF/SIC and MWF/PIC structures over the conventional SIC and PIC, MMSE, and RAKE recelvers are determined for a highly loaded synchronous DS-CDMA system in frequency selective multipath, and the computational costs and performance benefits are presented.