New Recursive Space-Time Trellis Codes From General Differential Encoding

In this paper, a recursive space-time trellis coding (RSTTC) from general differential encoding is proposed for multiple antenna systems, where general differential encoding is implemented separately from the space-time matrix modulation. The general differential encoding is achieved by introducing a new multiplication on a set of symbols (called trellis codewords) such that the corresponding RSTTC has its minimum error event length 3 or above and in the meantime it has the minimum number of states. The space-time matrix modulation is the mapping of the differentially encoded symbols to a set of space-time matrices (called modulation codewords). Due to the separation of differential encoding and space-time matrix modulation, more freedom on the design of modulation codewords (or a space-time code) exists, which may result in a larger diversity product (or determinant distance or product distance or coding advantage) than that the existing combined differential encoding and space-time matrix modulation can achieve in the concatenation with an outer binary channel encoder proposed by Schlegel and Grant. A new design of modulation codewords is then proposed for the RSTTC with larger diversity products than the existing schemes. Simulation results are finally presented to show that our new design significantly outperforms the existing schemes