Iterative Joint-Over-Antenna Detection and WNRA Decoding in Single-Carrier Multiuser MIMO Systems

In this paper, we propose a combined iterative detection and decoding technique that is capable of achieving the maximum diversity of order N_TtimesLtimesN_R over single-carrier multiple-input-multiple-output (MIMO) frequency-selective Rayleigh fading channels, where N_T and N_R denote the number of transmit and receive antennas, respectively, and L is the number of multipath components. The so-called space-time weighted-nonbinary-repeat-accumulate (ST-WNRA) codes are considered in our paper due to their ability to provide a full transmit antenna diversity and their relatively simple encoding and decoding algorithms. Multipath diversity is obtained using a joint-over-antenna turbo-equalization technique based on the minimum-mean-square-error filtering with soft interference cancellation. Computer simulations demonstrate that our proposed turbo-equalized system with ST-WNRA codes is capable of achieving the maximum diversity order with a relatively short codeword length and that the multiuser performance approaches the single-user bound so far as the number of users is smaller than or equal to the number of receive antennas in multiuser MIMO setups. We will also show that by modifying our proposed scheme to an equivalent multilevel coded system, higher bandwidth efficiency can be achieved at the expense of a performance loss while the system still retains the maximum diversity benefit