Patent ID: 7167526

Claim:
A method of achieving transmit diversity gain for frequency selective fading channels in a communication system that is a time-division duplex system and has a base station with multiple transmit antennae and a mobile terminal with at least a single receive antenna, the method comprising the steps of: providing a signal to be transmitted s(n); space-time encoding the signal s(n) to produce at least two separate signals s 1 (n),s 2 (n), each on a respective output; feeding each output signal s 1 (n),s 2 (n) to a zero-forcing pre-equaliser having a respective function g 1 (k), g 2 (k) to produce an output signal x 1 (n), x 2 (n); feeding the output signal x 1 (n), x 2 (n) of each pre-equaliser to a transmit antenna; transmitting the output signals x 1 (n), x 2 (n) over respective physical channels h 1 (k), h 2 (k); receiving the output signals x 1 (n), x 2 (n) at at least a single receive antenna; and space-time decoding the received signals, wherein the functions g 1 (k), g 2 (k) of the zero-forcing pre-equalisers are selected such that the channel responses g 1 (k)*h 1 (k), g 2 (k)*h 2 (k) of the respective physical channels h 1 (k), h 2 (k) are flat fading channels; and deriving real channel coefficients from uplinik channel coefficients for use in selecting the functions g 1 (k), g 2 (k) of the pre-equalisers.