A new super-orthogonal space-time code with 32QAM for mobile communications

Abstract

Abstract —We design a 64-state super-orthogonal space-time (ST) trellis code allowing wireless communications with a data rate of 5 bits per signaling interval. Considering a mobile wireless communications system with two transmit antennas, we form a four-dimensional (4D) signal constellation as a Cartesian product of two 2D rectangular signal sets. The first antenna transmits a 4D point as two concatenated 2D points in two consecutive baud intervals. The 2D symbols transmitted by the second antenna are not independent, but so chosen as to form, together with the symbols transmitted by the first antenna, the entries of a 2 × 2 orthogonal matrix. For a rectangular constellation, as much as four sets of 2 × 2 orthogonal matrices can be built. To obtain a higher data rate, the union of two of them is used to construct a super-orthogonal signal set. With 2 × 2 orthogonal matrices, we then label the state transitions of a trellis diagram describing the operation of the encoder. For the performance analysis, two different channel models are employed. The first channel model is based on the assumption that the paths between different pairs of transmit-receive antennas are uncorrelated, while the second model takes into account the effect of spatial antenna correlation at both the base station (BS) and at the mobile station (MS). The analysis of the frame-error rate (FER) and the bit-error rate (BER) demonstrates the excellent performance of the proposed high data rate super-orthogonal ST trellis code.