Open-loop and closed-loop transmit diversity techniques—overview and new results

We present an overview of multiple-input multiple-output (MIMO) wireless communication systems followed by some of the new techniques proposed by us to enhance performance. Firstly, some of the popular transmit and receive diversity schemes available in the literature are discussed and issues like diversity, rate, power distribution, decoding complexity, decoding delay, amount of feedback and feedback delay and their tradeoffs to achieve reliable and cost effective communications are described. We then analyze the merits and demerits of some of the open-loop (no feedback) and closed-loop (with feedback) schemes, and discuss various methods proposed by us recently to improve the performance of such schemes. The symbol error rate (SER) performance of the various schemes are compared through computer simulations. © 2005 Taylor & Francis Group, LLC.