Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 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 multi-user interference is
experienced at any of the receivers. This low-complexity 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 to maintain a bounded rate loss. Finally, we investigate a simple
scalar quantization scheme that is seen to achieve the same scaling behavior as
vector quantization.

25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph