An interference cancellation scheme for the multiuser TRDMA uplink system

Abstract

The concept of Time Reversal Division Multiple Access (TRDMA) has recently been proposed as a promising medium access technology for the multi-user wireless broadband communications. Compared with the existing multi-carrier technology like OFDM/OFDMA, the TRDMA provides a cost-effective single-carrier alternative technology to combat the inter-symbol interference (ISI) for broadband communications, and at the same time leverages the degrees of freedom in a large number of multi-paths to form a unique high-resolution spatial focusing effect. Previous work on TRDMA mainly focus on the multi-user downlink system. In this paper, we first introduce a TRDMA-based multi-user uplink architecture and then propose a 2-dimensional (2D) parallel interference cancellation scheme to further enhance the system performance. The TRDMA uplink architecture keeps the cost of end-users at a minimum level, and reuses the processing power at the base station (BS) that has already been made available for the downlink. The proposed 2D parallel interference cancellation scheme utilizes the tentative decisions of detected symbols to effectively cancel the interference in both the time domain (i.e. ISI) and the user domain (i.e. inter-user interference (IUI)), which significantly improve the bit-errorrate performance in the high signal-to-noise-ratio (SNR) regime. Simulation results are provided and compared with the basic TRDMA system without interference cancellation.