A discrete-time model of DS-CDMA signaling using multiple transmit and receive antennas employing linear transceiver filters is derived. For each link, connecting a base-station to a wireless mobile user, the downlink signal to interference plus noise ratio (SINR) after despreading is derived analytically, and as a by-product an exact closed-form solution of the orthogonality factor is obtained.

The orthogonality factor is derived for any linear receiver structure that is implemented by a bank of correlators and for any linear combining techniques (such as MRC and MMSE), and for any number of transmit and/or receive antennas that utilize transmit (pre-RAKE) and receive (post-RAKE) filtering.

The MIMO DS-CDMA model is derived using a filter representation, and is extended to a vector/matrix formulation that permits a systematic and efficient way of computing the SINR in a radio network simulator.