Efficient weight vector representation for closed-loop transmit diversity

For a closed-loop transmit (Tx) diversity, the Tx weights are calculated at a receiver, and fed back to a transmitter. As the number of Tx antennas increases, the potential gain of closed-loop Tx diversity may be significant. However, the amount of feedback information linearly increases, and the performance improvement of a closed-loop Tx diversity system may not be as significant as expected due to delay in feedback process. Thus, an efficient Tx weight representation, which can reduce the amount of feedback information, is needed. A Tx weight vector representation is presented, and its performance is analyzed.