Abstract: A base station (1) in a radio communication system is provided with an antenna array 2, 3 for communication with a plurality of mobile stations (4, 5). The transmissions of the base station (1) are optimised by adjusting the phase between the signals transmitted by each antenna (2, 3) so that the product of the propagation channel estimates is maximised. The invention has particular application to CDMA-TDD modes of operation where it has been shown to perform favourably in comparison with known transmit diversity techniques. A further advantage is that it does not require added complexity in the channel estimation at each mobile station (4, 5).

Abstract: A method of improving capacity in a duplexing scheme is provided. The duplexing scheme has a first band of frequencies and a second band of frequencies. The method comprises the steps of: determining an amount of available capacity on the first band of frequencies (steps 402, 404, 410), transmitting, on the first band of frequencies, a variable amount of feedback data corresponding to the amount of available capacity on the first band of frequencies, the feedback data comprising data for improving the quality of communications on the second band of frequencies, and optimizing (steps 406, 408, 412, 414) transmissions on the second band of frequencies using, when available, the feedback data.

Abstract: Antenna weights for a transmit path (3) between two communication devices (1, 2), the first device (1) having an antenna array (4, 5, 6) are generated in the second device (2) and fed back to weighting circuitry (9, 10, 11, 12) in the first device (1). The invention is particularly applicable to multicarrier systems such as OFDM systems. Only weights for those sub-carriers identified as being received with comparatively poor signal quality are calculated and fed back to the first device (1), thus limiting the additional overhead requirements to a minimum.