Space-time diversity design for blind estimation and equalization over frequency selective channels

Wireless communications often exploit guard intervals between data blocks to reduce inter-block-interference in frequency selective channels. Here we propose a dual-branch transmission scheme that utilizes guard intervals for blind channel estimation and equalization. Unlike existing diversity schemes, in which different antennas transmit delayed, zero-padded, or time reversed versions of the same signal, we use two antennas to transmit independent data streams. It is shown that for systems with two transmit antennas and one receive antenna, blind channel estimation can be carried out based only on the second order statistics of the symbol rate sampled channel output. The proposed approach involves no pre-equalization and has no requirement on channel coprimeness. It is also shown that in combination with the T-BLAST structure and turbo coding, significant improvement can be achieved in the overall system performance.