Performance Improvement of Binary Sensor-Based Statistical Space-Time Block Code Cooperative Diversity Using Limited Feedback
The statistical cooperative diversity, based on space-time block codes (statistical STBC cooperative diversity) is proposed for binary sensors by several authors. Since Alamouti’s code is the only orthogonal code which achieves full diversity and full rate for two sensors, it is used in their works, and their achievable diversity order is 2. Instead of using Alamouti’s code, we use extended cooperative space-time block coding (ECBSTBC) which achieves full diversity which is shown analytically and full rate for an arbitrary number of sensors if a limited feedback is available at the active sensors. Another method to increase diversity in cooperative communications is sensor (relay) selection. However, the sensor selection method may lead to the selection of the same (near) sensor for transmission over a long period causing the energy hole problem in sensor networks. The ECBSTBC which utilizes every sensor in sight thus distributes the energy consumption among active sensors and alleviates the energy hole problem. In addition, it can be shown with detailed simulations that the ECBSTBC outperforms both the statistical STBC cooperative diversity and the sensor selection schemes.