Turbo space-time codes with time varying linear transformations

Turbo space-time codes with symbols preceded by randomly chosen unitary time variant linear transformations (TVLT) are investigated in this paper. It is shown that turbo codes with TVLT achieve full diversity gain and do not require exhaustive tests of the rank criterion. We prove that the coding gain performance of turbo space-time codes with TVLT improves with the Hamming distance between codewords (number of different columns). As an additional benefit of the application of TVLT, with the removal of the constant modulation condition, we prove that throughput rates achieved by these codes are significantly higher than those for conventional space-time codes. Numerical results are provided to demonstrate diversity gains, coding gains and rates of turbo space-time codes with TVLT.