Design of high performance MIMO receivers for LTE/LTE-A uplink

In this paper we design high performance multiple-input-multiple-output (MIMO) receivers for the DFT-Spread-OFDM based long term evolution (LTE) cellular uplink. In the LTE uplink multiple single-antenna users can be scheduled on the same time-frequency resource block via space division multiple access. The designed receivers are also applicable to the LTE-Advanced cellular uplink wherein simultaneous transmission of multiple streams by a single user will be possible. Two types of advanced non-linear receivers are considered and optimized, namely, a receiver based on a two-symbol max-log soft-output demodulator (two-symbol MLD) and a turbo minimum mean squared error successive interference cancelation (turbo MMSE-SIC) receiver. Based on extensive simulations, it is shown that both the two-symbol MLD and the turbo MMSE-SIC receivers exhibit superior performance compared to the conventional linear MMSE (LMMSE) receiver. In general, the turbo MMSE-SIC receiver is robust to timing offsets and offers the best performance but also introduces larger latency and higher computational complexity. Upon employing a proposed new pairing method, the two-symbol MLD based receiver is also found to yield a good performance that is robust to timing offsets and which entails a moderate complexity and latency.