Delay Tolerant Feedback Based MISO Communication System

In this work, we propose and analyze the performance of delay-tolerant feedback based multiple-input-single-output wireless communication system. Input symbols are encoded by employing orthogonal space-time block codes. It is well known that with the help of full channel state information (CSI) transmitter adapts its condition to achieve full diversity and coding gain. However, due to bandwidth constraints and channel coherence time constraints it is not feasible to acquire full CSI at the transmitter. Therefore, a limited feedback-based precoder selection scheme is used in practical wireless communication systems. Due to the coherence constraint of the wireless feedback link, the transmitter may receive outdated CSI. This delayed feedback information leads to select precoder not as per the actual CSI which significantly degrades the system performance. Therefore it is imperative to develop a delay-tolerant-weighing scheme to overcome the effects of outdated feedback information. The exact and asymptotic outage probability expressions of the considered system are derived over delayed feedback information for Rician faded channel at k = 1 and k = 2. The optimal values of the weights of the diagonal precoder matrix are obtained by minimizing the derived closed-form expression of outage probability. It is evident from the simulated and analytical results that the proposed delay-tolerant-weighing scheme attain full diversity. Furthermore, it outperforms the equal power allocation scheme and also other existing schemes in terms of coding gain under outdated feedback information.