A simple scheme for transmit diversity using partial channel feedback

Previous work in wireless communications focuses on transmit diversity as a convenient means to obtain diversity gain where receivers have a limited number of antennas. Unlike at the receiver exploiting the diversity advantage from multiple transmitting antennas is difficult since channel knowledge is not readily available at the transmitter and because the signals arrive having been combined in space. To alleviate this problem we propose a simple scheme called partial phase combining (PPC) which uses partial knowledge about the relative phases of the channels to select the antenna phases. The proposed algorithm is useful in systems where the channel is correlated from frame to frame. Monte Carlo simulations are used to compare performance with other proposed transmit diversity systems.