Bit Error Performance of Orthogonal Space-Time Block Codes over Time-Selective Channel

Most of the existing works on space-time block codes (STBC) assume the channels are quasi-static, i.e., they remain invariant within one block. This assumption is not always true. In a more general case of time-selective channel, the channel matrix is no longer orthogonal. If conventional linear decoder is applied as it is in the quasi-static channel, it will introduce an irreducible error floor. In order to improve the performance, we can use zero-forcing decoder, which completely removes the interference. In this paper, we analyze the average bit error performance for BOTH conventional linear and zero-forcing decoders in the time-selective channels. The closed-form average bit error probabilities are obtained for both decoders, together with the irreducible error floor for the conventional linear decoder. Asymptotic analysis and numerical examples are also provided.