Patent ID: 7181246

Claim:
A communication system, comprising: a space-time transmitter having multiple transmitting antennas and a space-time encoder, wherein each of the transmitting antennas transmits signals over at least one wireless channel, wherein the transmitted signals represent space-time encoded information symbols; a space-time receiver having multiple receiving antennas configured to receive the transmitted signals over the wireless channel, wherein a received signal from each receiving antenna is processed by the space-time receiver to extract the information symbols that have been transmitted; wherein the space-time receiver is configured to determine at least information related to channel coefficients corresponding to a quality of the wireless channel and to provide, over a feedback channel to the space-time transmitter, a channel information signal representing the channel coefficient information; wherein the space-time encoder is configured to adaptively construct a space-time signal set for transmission based on the information symbols delivered to each transmitting antenna and based on an availability and quality of the channel coefficient information received from the space-time receiver over the feedback channel to enhance a signal to noise ratio obtained at the space-time receiver; and wherein the transmitted signals have a form of: s = [ s 11 s 12 s 21 s 22 ] where entry S km denotes the signal to be transmitted via one of first and second transmit antennas k at one of first and second adjacent time instances, and wherein at the first time instant, signals s 11 and s 21 are simultaneously transmitted via respective first and second antennas, wherein s 11 = c 1 2 ⁢ and ⁢ ⁢ s 21 = 1 2 ⁡ [ v ⁡ ( 1 - λ ) 1 / 2 ⁢ c 1 + λ 1 / 2 ⁢ c 2 ] ⁢ wherein c 1 and c 2 represent first and second input symbols, wherein v is a weighting coefficient based on a phase value of the channel coefficient information received from the receiver, and |ν| 2 =1, wherein λ is a distribution coefficient, and wherein the distribution coefficient λ is less than or equal to 1 and allocates energy between symbols c 1 and c 2 to be transmitted in accordance with a quality of the received channel coefficient information: and wherein at the second time instance, signals s 12 and s 22 are simultaneously transmitted via the respective first and second antennas, wherein, s 12 = - c 2 * 2 ⁢ and s 22 = 1 2 ⁡ [ - v ⁡ ( 1 - λ ) 1 / 2 ⁢ c 2 * + λ 1 / 2 ⁢ c 1 * ] wherein * represents a complex conjugate of a value, and the weighting coefficient v in s 21 and s 22 is applied so that the paired transmitted signals (s 11 and s 21 , or s 12 and s 22 ) are aligned in phase for the space-time receiver.