Space-Time Turbo Codes

Introduction: Recently, there has been a surge of interests in the design of the so called \space{time" codes which take advantage of both the spatial diversity provided by multiple antennas and the temporal diversity available with time{varying fading. The previous proposed space{time codes were mainly based on trellis codes or orthogonal block codes. In those codes, the number of transmitter antennas is xed for each code construction. We propose a new class of scalable space{time codes based on turbo codes or turbo trellis codes [1]. They will be referred as space{time turbo codes (STT) in the sequel. The scalability implies that the code rate and number of transmitter antennas can be easily adapted to di erent design requirements without redesigning the main part of the code. We present the encoder, channel model followed by the design criteria, simulation results and conclusions. Encoder and Channel Model: The encoder of the proposed space{time turbo code consists of a turbo code encoder or a turbo trellis code encoder followed by a symbol interleaver and multiplexer (Fig. 1). Puncturing the code allows a variety of code rates and the number of transmitter antennas can be arbitrary as long as it is not too close to the free distance of the turbo code.