Cooperation transmission without perfect synchronization for wireless sensor networks using signal space diversity and STBC

Cooperative transmission breaks away from traditional transmission which only has single transmitter and single receiver in wireless networks, which enable single antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter in order to achieve transmit diversity. Space-time block coding (STBC) is an attractive transmission diversity technique because of its linear complexity. Furthermore, signal space diversity can increase the diversity order through interleaving over coordinates and choosing a proper signal constellation. In this paper, cooperative transmissions for wireless sensor networks are considered. In order to improve the system performance, a new cooperative transmission scheme without perfect synchronization using both signal space diversity and STBC is proposed. It is shown by simulation that compared to the traditional transmission scheme with signal space diversity and the STBC-encoded cooperative transmission scheme without signal space diversity, the new scheme can provide further performance improvement by increasing the diversity order, and can save more energy in wireless sensor networks.