Feedback Load Reduction in Multiuser MIMO Broadcast Channel
Date Issued
2010
Date
2010
Author(s)
Tsai, Yu-Lun
Abstract
We consider the downlink of a multiuser multiple antennas channel. It is
known that when full channel state information is available at the transmitter
(full CSIT), the sum capacity can be achieved. Thus, for the system which
employs frequency division duplex (FDD), this requires each user to feed back
their channel state information (CSI) to the base station (BS), which incur a
large aggregate feedback bandwidth, especially when the number of users is
large. We consider zero-forcing beamforming (ZFBF) with semi-orthigonal
user selection(SUS) in which CSI is split to channel direction information
(CDI) and channel quality indicator (CQI). We propose a novel scheme to
reduce feedback load by using the threshold-based feedback strategy. The
key feature of the proposed approach is the use of order statistic concept to
construct multiple thresholds on CQI not only to reduce feedback load but
also to be the representative levels instead of using the quantizer. We show
that by employing the proposed scheme the feedback load can be signi￣-
cantly reduced, and the sum-rate performance is better than the traditional
feedback schemes.
Subjects
multiuser multiple-input multiple-output (MU-MIMO)
down- link channel
zero-forcing beamforming (ZFBF)
feedback load reduction
order statistic
semi-orthogonal user selection (SUS)
Type
thesis
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