Till now most of the concentration was on diversity gains achieved by using both transmit and receive antennas in a multiple-input multiple-output (MIMO) channel. However, multiple transmit antennas can be utilized to achieve other goals as well. A higher capacity and as a result a higher transmission rate is possible by increasing the number of transmit antennas. Assume a MIMO channel with equal number of transmit and receive antennas. Then in a rich scattering environment the capacity increases linearly with the number of antennas without increasing the transmission power. This results in the possibility of transmitting at a higher rate, for example by using spatial multiplexing. If the number of transmit antennas is not the same as the number of receive antennas, in general one can transmit up to min{N, M} symbols per time slot, where N is the number of transmit antennas and M is the number of receive antennas. For example, if M ≥ N, one can send N symbols and achieve a diversity gain of M − N + 1. Note that for equal number of transmit and receive antennas, the diversity gain in this case is one. On the other hand, the maximum spatial diversity while transmitting only one symbol per time slot is MN. Therefore, the advantage of a MIMO channel can be utilized in two ways: (i) to increase the diversity of the system and (ii) to increase the number of transmitted symbols. For the general case of more than one transmit antenna, M ≥ N > 1, there is a theoretical trade-off between the number of transmit symbols and the diversity of the system. For one transmit antenna, in both cases one symbol per time slot is transmitted and the two systems coincide.