Combined array processing and space-time coding

The information capacity of wireless communication systems may be increased dramatically by employing multiple transmit and receive antennas. The goal of system design is to exploit this capacity in a practical way, An effective approach to increasing data rate over wireless channels is to employ space-time coding techniques appropriate to multiple transmit antenn as. These space-time codes introduce temporal and spatial correlation into signals transmitted from different antennas, so as to provide diversity at the receiver, and coding gain over an uncoded system. For large number of t ransmit antennas and at high bandwidth efficiencies, the receiver may becom e too complex whenever correlation across transmit antennas is introduced. This paper dramatically reduces encoding and decoding complexity by partiti oning antennas at the transmitter into small groups, and using individual s pace-time codes, called the component codes, to transmit information from e ach group of antennas. At the receiver, an individual space-time code is de coded by a novel linear processing technique that suppresses signals transm itted by other groups of antennas by treating them as interference. A simpl e receiver structure is derived that provides diversity and coding gain ove r uncoded systems. This combination of array processing at the receiver and coding techniques for multiple transmit antennas can provide reliable and very high data rate communication over narrowband wireless channels. A refi nement of this basic structure gives rise to a multilayered space-time arch itecture that both generalizes and improves upon the layered space-time arc hitecture proposed by Foschini.