Designing Space-Time Codes Using Orthogonal Designs

Abstract: This thesis deals with coding schemes for systems with multiple transmit antennas. The problem of finding optimal transmission schemes for the case when the transmitter knows the channel and the case when the transmitter does not know the channel are considered. Also considered is the case when some partial feedback is possible from the receiver to the transmitter.When the transmitter knows the channel perfectly, a beamforming solution is shown to be optimal. To tackle the case where the transmitter does not know the channel perfectly, schemes based on orthogonal designs are proposed that give the best performance under some conditions. A differential detection scheme is also proposed where neither the transmitter nor the receiver has to know the channel. The thesis also considers the concatenation of a conventional (scalar) coding scheme with a space-time modulation scheme and shows how optimum coded diversity can be obtained with this concatenation. An alternative to the concatenation method concatenation of a space-time modulation scheme with a scalar code is to develop space-time trellis codes.Orthogonal designs are usually associated with space-time block codes. In this thesis the design of space-time trellis codes based on orthogonal designs is considered. A turbo implementation of the new trellis codes is also proposed.