Spectrum Shaping Technique Combined with SC/MMSE Turbo Equalizer for High Spectral Efficient Broadband Wireless Access Systems

This paper proposes a spectrum shaping technique exploiting frequency clipping for frequency domain soft canceller with minimum mean square error (FD-SC/MMSE) based turbo equalization systems, of which aims to achieve high spectral efficiency and efficient energy transfer from a transmitter to a receiver, as well as to provide a novel spectrum division multiplexing strategy. In the proposed scheme, the water-filling strategy is modified to clip more spectrum components with lower signal to noise power ratio, and transmit power allocated to the clipped spectrum components are evenly distributed to the non-clipped components thereby concentrates transmit power on spectrum with higher channel gain. Furthermore, the proposed spectrum shaping technique is applied to user multiplexing in the frequency domain with higher spectral efficiency. Computer simulation including extrinsic information transfer (EXIT) analysis confirms that the proposed scheme is effective in enhancement of spectral efficiency with low power penalty.