Constructing space-time trellis codes using orthogonal designs

In this paper we consider the design of space-time trellis codes using orthogonal designs. We derive a condition on the codewords to obtain the maximum received signal energy and show that the codes based on orthogonal designs satisfy this condition. We consider in detail the design of a trellis code for two transmit antennas. The new code we develop has a higher diversity in fast fading and a higher coding gain in quasi-static fading when compared to other existing space-time codes. We also consider a turbo implementation of the new trellis code which results in very high diversity gains in fast fading channels.