Patent ID: 7136627

Claim:
A method for selecting a diversity mode (A, B, C) to be applied by a transmitter having two cross-polarized antenna arrays (Ant 1 , Ant 2 ), each representing a diversity branch, for transmission diversity, the method comprising the steps of: providing (S 10 ) a plurality of diversity mode performance chart look-up tables (LUT, LUT 1 , LUT 2 , LUT 3 ), each performance chart look-up table mapping a respective individual diversity mode (A, B, C) out of a plurality of individual diversity modes to a respective pair of time correlation value (TC) and space correlation value (SC) for said two cross-polarized antenna array beams, wherein a respective individual diversity mode is presented by a mapping area, wherein the plurality of performance chart look-up tables is parameterized by an indication of a ratio (P 1 /P 2 ) of received powers from said diversity branches, and the mapping is different for different performance charts, first determining (S 11 ) the ratio of received powers from said diversity branches, second determining (S 12 ) the actual time correlation and space correlation for said pair of two cross-polarized antenna arrays, first selecting (S 13 ) one of said performance chart look-up tables dependent on determined ratio (P 1 /P 2 ) of received powers from separate beams, and second selecting (S 14 ) one of said individual diversity modes (A, B, C) according to the mapping to the determined actual time correlation (TC) and space correlation (SC) values from said first selected performance chart look-up table.