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arXiv · 0711.3251

Limited Feedback-based Block Diagonalization for the MIMO Broadcast Channel

Niranjay Ravindran·Nihar Jindal
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Abstract

Block diagonalization is a linear precoding technique for the multiple antenna broadcast (downlink) channel that involves transmission of multiple data streams to each receiver such that no multi-user interference is experienced at any of the receivers. This low-complexity scheme operates only a few dB away from capacity but requires very accurate channel knowledge at the transmitter. We consider a limited feedback system where each receiver knows its channel perfectly, but the transmitter is only provided with a finite number of channel feedback bits from each receiver. Using a random quantization argument, we quantify the throughput loss due to imperfect channel knowledge as a function of the feedback level. The quality of channel knowledge must improve proportional to the SNR in order to prevent interference-limitations, and we show that scaling the number of feedback bits linearly with the system SNR is sufficient to maintain a bounded rate loss. Finally, we compare our quantization strategy to an analog feedback scheme and show the superiority of quantized feedback.

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Niranjay Ravindran, Nihar Jindal. 2007-11-21. Limited Feedback-based Block Diagonalization for the MIMO Broadcast Channel. https://doi.org/10.1109/jsac.2008.081013

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