Closed-Loop Transmit Diversity with Imperfect Feedback

The closed-loop transmit diversity technique is used to improve the performance of the downlink channel in MIMO communication systems. In these closed-loop systems, feedback delay and feedback error, as well as the sub-optimum reconstruction of the quantized feedback data, are the usual sources of deficiency. We address the efficient reconstruction of the beamforming weights in the presence of the feedback imperfections, by exploiting the residual redundancies in the feedback stream. Focusing on the issue of feedback delay, we propose two approaches to improve the performance. One is based on using a channel predictor at the receiver to compensate for the delay, and using a joint source-channel coding (JSCC) method similar to our previous work [2] to compensate for the feedback error. Another approach deals with the feedback imperfections in a unified reconstruction algorithm using JSCC techniques. Furthermore, we introduce the concept of Blind Antenna Verification which can substitut...

• Type: Journal
• Year: 2010
• Where: TWC
• Authors: A. Heidari, Amir K. Khandani
• Keywords: Artificial Intelligence, Feedback, Feedback Delay, Feedback Imperfections, TWC 2010