Diversity for the direct-sequence spread spectrum system using multiple transmit antennas

Diversity is employed to improve the performance of a communication system in a fading environment. A novel form of diversity which is useful especially in situations where frequency diversity is not available is proposed. This technique uses multiple transmit antennas and the antennas are weighted by suitably determined time-varying phase offsets. It is shown that with this technique, M transmit antennas and an L-branch RAKE receiver gives rise to diversity of order LM