Reduced-Complexity Single-Carrier E-SDM for Wideband Transmissions

In the case of broadband wireless access systems operating over non-line-of-sight (NLOS) links, the multipath can be severe. This leads to frequency-selective fading channel which causes distortions of the received signal. The single-carrier (SC) modulation method combined with frequency-domain equalization (FDE) at the receiver has been proposed as an alternative to the orthogonal frequency division multiplexing(OFDM) system due to its relative small peak-to-average power ratio (PAPR) achieved at a similar complexity. Furthermore, an eigenbeamspace division multiplexing (E-SDM) technique can be applied to the single-carrier system to improve the spectrum efficiency. This scheme makes use of both spatial and frequency diversity while maintaining a low PAPR. The computation load still remains a challenge for the uplink transmission where the power resources are limited, therefore, in this paper we propose some reduced complexity techniques. The transmission performance of these techniques and the trade-off between complexity and bit error rate (BER) are evaluated in a frequency-selective Rayleigh channel by computer simulations.