A novel MIMO STC-OFDM technique with high spectral efficiency and high performance

This paper presents a novel MIMO STC-OFDM technique to achieve both high spectral efficiency and high performance over frequency selective channels. This is accomplished by a combination of MIMO OFDM, group coded transmit signals and antennas, array processing at the receiver for interference suppression on a per carrier basis, and a new decoding scheme. The group coding reduces the complexity of receivers in space time coded MIMO systems. It partitions transmitter antennas into small groups. The received signals are then processed by a technique called group interference suppression. By using interference suppression on a per carrier basis after the FFT at the receiver, the scheme lends itself to use on frequency selective multipath channels. Finally, a novel decoding scheme is employed. It uses samples from frequencies K/2 apart, where K is the total number of frequencies, to introduce another element of diversity, and then uses a least squares step to yield reliable statistics for symbol detection. At 22 dB, this new scheme achieves a BER of 4×10⁻⁵, without coding or interleaving. The data rate achieved, over a bandwidth of 20 MHz, is 144 Mbps with a corresponding spectral efficiency of 9.6 bits/s/Hz. In addition, the scheme is a low complexity scheme.