Receiver Design for Orthogonal Space-Time Block Coding for Four Transmit Antennas over Time-Selective Fading Channels

A key assumption in all orthogonal space-time block coding (O-STBC) schemes is that the channel remains static over the length of the codeword. However, time selective fading channels do exist, and in such case the conventional O-STBC receiver will not function properly: even a relatively small variation in channel state can result in a large error floor. This paper presents an effective solution to this issue for the case of four transmit antennas. At the receiver, a simple zero forcing decoder is derived. To improve the performance of the decoder under certain channel conditions, the original O-STBC encoder is also modified accordingly. Computer simulations confirmed the effectiveness of the new procedure.