MIMO Broadcast Channels with Block Diagonalization and Finite Rate Feedback

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 multiuser interference is experienced at any of the receivers. This lowcomplexity scheme operates only a few dB away from capacity but does require very accurate channel knowledge at the transmitter, which can be very difficult to obtain in fading scenarios. 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 vector 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...

• Type: Journal
• Year: 2006
• Where: CORR
• Authors: Niranjay Ravindran, Nihar Jindal
• Keywords: Accurate Channel Knowledge, Channel Knowledge, CORR 2006, Education, Linear Precoding Technique