Distributed Cooperative Space Time Trellis Code

Abstract

The wireless communications industry has been undergoing tremendous changes in the last few years. There has been a spectacular growth in the internet and mobile communication services in the last decade. Wireless Internet and multimedia services are introduced in the 3G mobile phones, require much higher data rates than those available with current radio technology. Video telephony and picture messaging introduced by 3G phones generate huge up link traffic. Given a limited Spectrum the only way to support high data rates is to develop new spectrally efficient radio communication techniques. It was shown recently that multiple input multiple output (MIMO) system have a potential to significantly increase spectral efficiency in the wireless communications. Space Time codes are practical techniques used to approach the theoretical MIMO spectral efficiencies Unfortunately uplink transmit diversity is not directly applicable to the cellular due to the small size of the mobile station and electromagnetic interaction of antenna elements on the small platform. Furthermore the channels corresponding to different antennas are correlated because of the miniature size of the mobile phone. So, there is a need for such ideas to be extended to the macroscopic arena, where space-time coding is performed over transmit antennas that are not necessarily co-located. Mobile antennas are omni directional. Signals transmitted towards the destination can be "overheard" at the other MTs(partner). Partners (Adjacent MTs). process this overheard information and re-transmit towards the destination. These Partnering mobiles form a Virtual Antenna Array. This approach successfully gives solution to the problem of just one receiving antenna in a handset. In our proposed scheme space-time trellis coding is performed over transmit antennas that are not necessarily co-located. The Idea is called Distributed Space Time Trellis Coding. Cooperative Distributed Space Time Trellis Coding have also been analyzed to increase the performance of Distributed Space Time Code.