A Multiuser TRDMA Uplink System with 2D Parallel Interference Cancellation

The concept of Time-Reversal Division Multiple Access (TRDMA) has recently been proposed as a promising medium access technology for wireless broadband communications. Previous work on TRDMA mainly focuses on the multi-user downlink system. In this paper, we first introduce a TRDMA-based multi-user uplink architecture and then propose a 2D parallel interference cancellation scheme to enhance 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 that has already been made available for the downlink. The proposed 2D parallel interference cancellation scheme utilizes tentative decisions of detected symbols to effectively cancel both inter-symbol interference and inter-user interference, which significantly improve the bit-error-rate (BER) performance in high SNR regime. To further improve BER performance, a multi-stage processing can be implemented by cascading multiple stages of the proposed 2D interference cancellation, with a total delay that increases linearly with the number of stages, but independent of the number of users. The BER performance of the single-stage cancellation is analyzed, and the approximated theoretical result well matches the simulation results. Simulations are provided for up-to 3 stages of interference cancellation and compared with the basic TRDMA system without interference cancellation.