We consider the downlink of a multiuser MIMO channel, corresponding to a single cell with an Nt-antenna base station and K single-antenna mobile terminals (MTs). It is known that when full channel state information (CSI) is available at the transmitter (full CSIT) the capacity of the system scales as Nt log( P Nt logK), under a total power constraint P [1]. While, when the transmitter has no CSI, scaling reduces to that of a TDMA system. This paper examines the more realistic case of having an intermediate state of CSI. The key idea is based on a split of the allotted feedback between two stages: A first stage devoted to scheduling followed by a second stage for precoder design for the selected users. Based on an approximation of the achievable sum rate, we introduce a method for determining the splitting of the feedback rate so as to maximize performance and provide intuitions. We illustrate the gains of the 2-stage approach via Monte Carlo simulations.
A two-stage approach to feedback design in MU-MIMO channels with limited channel state information
PIMRC 2007, 18th IEEE Annual International Symposium on Personal Indoor and Mobile Radio Communications, September 3-7, 2007, Athens, Greece
Type:
Conference
City:
Athens
Date:
2007-09-03
Department:
Communication systems
Eurecom Ref:
2316
Copyright:
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See also:
PERMALINK : https://www.eurecom.fr/publication/2316
