Transmit diversity schemes for broadband mobile communication systems

This paper considers the problem of incorporating orthogonal space-time block coding in broadband wireless communication systems operating in rapidly-varying high delay-spread channels. We propose simple time-domain transmission schemes for allowing the space-time encoding and decoding processes to occur completely in the frequency domain of broadband single-carrier systems. We also propose receiver-processing techniques for mitigating the loss of orthogonality caused by rapidly-varying channels. The first receiver technique mitigates the effects of channel variation across the symbols of a coding interval. With more than one receive antenna, the second technique has the ability to mitigate the effects of channel variations occurring within an FFT interval in frequency-domain processed single-carrier systems. Simulation results are presented to verify the effectiveness of the proposed algorithms in OFDM and single carrier systems