Design of Optimum Space-Time Trellis Codes

In wireless mobile channels, a major challenge in providing high-data rate spectral efficient communication link is to overcome the multipath propagation effect small-scale fading. Diversity techniques are widely used to reduce the effects of multipath fading and improve the reliability of transmission without increasing the transmitted power or sacrificing the bandwidth. In most wireless communication systems a number of diversity methods are used in order to get the required performance. According to the domain where diversity is introduced, diversity techniques are classified into time, frequency and space diversity.Depending on whether multiple antennas are used for transmission or reception, we can classify space diversity into two categories: receive diversity and transmit diversity. Space time coding is a type of transmit diversity. Space-time coding is a coding technique designed for use with multiple transmit antennas. Coding is performed in both spatial and temporal domains to introduce correlation between signals transmitted from various antennas at various time periods. There are various approaches in coding structures, including space-time block codes (STBC), space-time trellis codes (STTC), space-time turbo trellis codes and layered space-time (LST) codes. This paper aims to implement the encoder and Viterbi decoder for space-time trellis codes,at same time evaluate the performance of some space-time trellis codes, To gain more insight of the performa--nce of space-time codes, simulation was carried out over several types of fading channels, including flat Rayleigh/Nakagami fading and frequency selective fading channels.