Super-orthogonal double space-time trellis code

Abstract

This study develops a new class of super-orthogonal trellis codes for four transmit antennas based on double space-time codes. The transmit antennas are divided into two groups, each having two transmit antennas. The information bits are demultiplexed into two streams; each is encoded independently using a super-orthogonal trellis code and then is transmitted from the corresponding antenna group. The resultant parallel-trellis code structure offers a higher data rate and, at the same time, it has a smaller number of parallel branches in the trellis encoder compared to a single stream encoder. The decoding is done using the a maximum likelihood (ML) decoder with an interference cancellation algorithm. It is shown that the proposed scheme reduces the required number of overall calculations by about half compared with super-orthogonal space-time trellis codes (SO-STTC) and super-orthogonal trellis coded spatial modulation (SOTC-SM). The performance of the designed codes is simulated and shows that an improvement in the frame error rate (FER) is achieved at 4 and 5 b/s.Hz compared with SO-STTC and SOTC-SM, while at 6 b/s.Hz, it achieved an improvement in the lower and medium range of signal-to-noise ratio (SNR) (< 22 dB).