Patent ID: 7649953

Claim:
A method of achieving differential multiple-length transmit diversity from orthogonal designs using at least two transmit antennas, comprising the steps: dividing a group of transmission bits into a first sub-group of transmission bits and a second sub-group of transmission bits; mapping the first sub-group of transmission bits onto constellation points of a differential transmit diversity coding scheme from an orthogonal design for coding the first sub-group of transmission bits; determining transmission symbols through differential encoding of the constellation points and previously transmitted transmission symbols for setup of a transmission symbol vector; and scaling a length of the transmission symbol vector for coding the second sub-group of transmission bits; wherein the step of mapping the first sub-group of transmission bits comprises a step of: mapping the 2·log 2 (M 1 ) transmission bits onto a constellation vector [A k B k ] of the differential transmit diversity coding scheme according to: A k =d 2t+1 d (0)*+ d 2t+2 d (0)* B k =−d 2t+1 d (0)+ d 2t+2 d (0) wherein d i are constellation elements of a M 1 -ary phase shift keying PSK modulation scheme; d(0) is a freely selectable reference point of the M 1 -ary phase shift keying PSK modulation scheme; and the length of the constellation vector is unit length |A k | 2 +|B k | 2 =1; the step of determining transmission symbols (S 2t+1 S 2t+2 ) through differential encoding is achieved according to: ( S 2t+1 S 2t+2 )= A k ( X 2t−1 X 2t )+ B k (− X* 2t X* 2t−1 ), wherein t is an index in time; and (X 2t−1 X 2t ) is a transmission symbol vector according to a previously transmitted matrix; and the step of scaling the transmission symbol vector length is achieved according to: ( x 2t+1 x 2t+2 )=√{square root over ( a q k )}·( s 2t+1 s 2t+2 ) wherein a is a constant; and q k ε{−M 2 +1, −M 2 +2, . . . , 0, 1, ., M 2 −1} is a length exponent.