Method and apparatus for optimizing transmission diversity

An apparatus transmitting in a communication system, said system comprising a transmitter, which comprises at least one first and at least one second antenna, and a receiver, which comprises at least one receiving antenna, said apparatus comprising:

• means for determining a transmit diversity scheme for at least one group of symbols from among a plurality of modulated symbols, comprising means for choosing a phase shift value of at least one symbol of said at least one group of symbols, said phase shift value being chosen based on:
• at least one phase shift parameter N, N being an integer, and
• N calculated quantities which are functions of responses (hk1, hk2) respectively between said at least one first antenna and said at least one receiving antenna and between said at least one second antenna and said at least one receiving antenna, at an emitting time k,
• means for phase shifting, which rotates said symbol of said phase shift value at a multiple of a π/N value, wherein phase shifting comprises a step of choosing a highest quantity Hn, among a plurality of quantities Hk(n) where 0≦n≦N−1 and wherein said highest quantity Hn determines a phase shift factor that is used to calculate said phase shift value.

A computer program product stored on a non-transitory computer readable medium, wherein the product includes instructions of program code for implementing a method of transmitting in a communication system, which includes a transmitter which comprises at least one first antenna and at least one second antenna and a receiver which comprises at least one receiving antenna, when run on a computer, wherein the method comprises:

• a step of determining a transmit diversity scheme for at least one group of symbols from among a plurality of modulated symbols, comprising at least one step of choosing a phase shift value of at least one symbol of said at least one group of symbols, said phase shift value being chosen based on:
• at least one phase shift parameter N, N being an integer, and
• N calculated quantities which are functions of responses (hk1, hk2), respectively, between said at least one first transmitting antenna and said at least one receiving antenna and between said at least one second transmitting antenna and said at least one receiving antenna, at an emitting time k;
• and
• a step of phase shifting, which rotates said symbol of said phase shift value at a multiple of a π/N value, wherein said step of phase shifting comprise a step of choosing a highest quantity Hn, among a plurality of quantities Hk(n) where 0≦n≦N−1 and wherein said highest quantity Hn determines a phase shift factor that is used to calculate said phase shift value.