Design of efficient receivers for DFT-S-OFDMA systems

DFT-spread-OFDMA (DFT-S-OFDMA) technique has been adopted as the uplink access scheme in emerging cellular systems such as the 3GPP long term evolution (3GPP-LTE), in order to reduce the peak-to-average-power ratio (PAPR). In this scheme, data symbols are pre-coded using a DFT operation at the transmitter before being sent to the OFDM modulator. Moreover, emerging cellular systems will also deploy multiple antennas at the base-station to increase the transmission reliability and/or system capacity. The design of low-complexity, low-latency and high-performance receivers for such DFT-S-OFDMA systems is an important open problem that has hitherto received little attention. In this paper, three receivers are proposed and examined for such DFT-S-OFDMA systems, which include a highly efficient group soft demodulator (referred to as the GMLSD), an enhanced iterative block decision feedback equalizer (IBDFE) and the conventional linear minimum mean square error (LMMSE) receiver. Monte Carlo simulations are performed to compare the performance of the proposed receiver algorithms. It is shown that the GMLSD receiver is ideal for the DFT-S-OFDMA based systems due to its low complexity and superior performance.