A method of serving a data stream to a target mobile terminal in a cellular communications network comprising a plurality of transmitting sites (14, 15), the method comprising: designating a first transmitting site and a second transmitting site as cooperating sites; at said first transmitting site, transmitting said data stream to said mobile terminal in accordance with a beamforming technique; and at said second transmitting site, transmitting said data stream to said mobile terminal in accordance with a beamforming technique, wherein beams transmitted by said second transmitting site are adjusted to result in constructive addition of beams arriving at said target mobile terminal from said first and said second transmitting sites; wherein one of said first and second transmitting sites comprises an antenna array and wherein said transmitting comprises transmitting the same said data stream from each antenna of said antenna array; the method characterized in further comprising: at a primary antenna of said antenna array, receiving channel quality information, CQI, feedback from said target mobile terminal; responsive to said CQI feedback, providing an indicator of a linear phase adjustment to each other antenna of said antenna array; and phase shifting beams transmitted by each of said other antennas by said indicated linear phase adjustment to thereby result in constructive addition of beams arriving at said target mobile terminal from said first and second transmitting sites; wherein said indicator comprises an indicator of a timing mismatch of arriving beams at said target mobile terminal; and wherein one of said first and second transmitting sites is considered as reference site, and the timing mismatch is reported by the target mobile terminal to the other one of said first and second transmitting sites. designating a first transmitting site and a second transmitting site as cooperating sites; at said first transmitting site, transmitting said data stream to said mobile terminal in accordance with a beamforming technique; and at said second transmitting site, transmitting said data stream to said mobile terminal in accordance with a beamforming technique, wherein beams transmitted by said second transmitting site are adjusted to result in constructive addition of beams arriving at said target mobile terminal from said first and said second transmitting sites; wherein one of said first and second transmitting sites comprises an antenna array and wherein said transmitting comprises transmitting the same said data stream from each antenna of said antenna array; the method characterized in further comprising: at a primary antenna of said antenna array, receiving channel quality information, CQI, feedback from said target mobile terminal; responsive to said CQI feedback, providing an indicator of a linear phase adjustment to each other antenna of said antenna array; and phase shifting beams transmitted by each of said other antennas by said indicated linear phase adjustment to thereby result in constructive addition of beams arriving at said target mobile terminal from said first and second transmitting sites; wherein said indicator comprises an indicator of a timing mismatch of arriving beams at said target mobile terminal; and wherein one of said first and second transmitting sites is considered as reference site, and the timing mismatch is reported by the target mobile terminal to the other one of said first and second transmitting sites. at a primary antenna of said antenna array, receiving channel quality information, CQI, feedback from said target mobile terminal; responsive to said CQI feedback, providing an indicator of a linear phase adjustment to each other antenna of said antenna array; and phase shifting beams transmitted by each of said other antennas by said indicated linear phase adjustment to thereby result in constructive addition of beams arriving at said target mobile terminal from said first and second transmitting sites; wherein said indicator comprises an indicator of a timing mismatch of arriving beams at said target mobile terminal; and wherein one of said first and second transmitting sites is considered as reference site, and the timing mismatch is reported by the target mobile terminal to the other one of said first and second transmitting sites.