Beam forming method

A method for beamforming in a radio communications system having a plurality of subscriber stations and a base station which has an antenna device with a plurality of antenna elements A1 to AM, comprising:

• transmitting a downlink signal to a subscriber station from each antenna element;
• for each of the antenna elements, weighting the downlink signal transmitted thereby with a weighting coefficient wi, i=1, . . . , M, the weighting coefficients forming a current weighting vector;
• in an initialization phase of the subscriber station:
• producing a first spatial covariance matrix from the downlink signal,
• determining eigen vectors of the first spatial covariance matrix, and
• transmitting the eigen vectors from the subscriber station to the base station and using the eigen vectors as first weighting vectors, which correspond respectively to radiation directions of the antenna elements;
• in a working phase:
• selecting one of the first weighting vectors at the subscriber station as a currently dominant weighting vector,
• transmitting an identifier of the currently dominant weighting vector from the subscriber station to the base station, and
• using the currently dominant weighting vector to weight the downlink signal in a subsequent time slot;
• in selected time slots, sending information on components of the first weighting vector from the subscriber station to the base station, the information on components of the first weighting vector being sent instead of the identifier of the currently dominant weighting vector;
• and
• performing the initialization phase at greater time intervals than the working phase.