Multistage MIMO receivers based on multi-branch interference cancellation for MIMO-CDMA systems

Abstract

In this paper we propose novel multistage receivers based on multiple parallel branches successive interference cancellation (MB-SIC) for the uplink of multiple-input multiple-output code-division multiple-access (MIMO-CDMA) systems. The proposed multistage receivers exploit a conventional ordered SIC for the first stage, followed by a grouping detection strategy and the novel MB-SIC scheme. The grouping detection strategy produces an estimate for the desired user, which consists of the user's antenna data streams, by using the detected information supplied from the first stage. The outputs of the second stage are processed by the proposed schemes using SICs which are equipped with different cancellation orders, so that the branches produce a group of estimated vectors for the desired user. Then, according to a selection rule the MB-SIC selects the refined estimated vector with the best performance for the desired user's antenna streams. Two selection rules are considered, namely, maximum likelihood (ML) and minimum mean square error (MMSE). The simulation results assess the proposed scheme against the best known spatial multiplexing schemes and show that it achieves a substantial capacity increase.