Low-Complexity Robust MISO Downlink Precoder
Design With Per-Antenna Power Constraints
Central Publication
Abstract
-
This paper considers the design of beamformers for
a multiple-input single-output (MISO) downlink system with perantenna
power constraints (PAPCs) that seek to mitigate the
impact of the imperfections in the channel state information
(CSI) that is available at the base station (BS). The goal of
the design is to minimize the outage probability of specified
signal-to-interference-and-noise ratio (SINR) targets, and to do
so at a low computational cost. The proposed design strategy
provides an efficient way to handle PAPCs, in addition to a total
power constraint, for a variety of precoding techniques, including
the offset maximization approach to robust beamforming, and
the nominal zero-forcing (ZF) and maximum ratio transmission
(MRT) approaches. Through observations regarding the
structure of the optimality conditions for each of the design
formulations, low-complexity iterative algorithms that involve the
evaluation of closed-form expressions are developed. In systems
with a large number of antennas, the computational cost of some
of these algorithms can be reduced to being linear in the number
of antennas, without a significant degradation in performance.
Simulation results show that the proposed robust designs can
provide substantial reductions in the outage probability while
satisfying the PAPCs.
Paper
- An earlier version of the paper is available on
arXiv
Other references
- An earlier conference version of this work is available as:
M. Medra and T. N. Davidson. Robust MISO downlink precoder design with per-antenna power constraints. In Proceedings of the 2015 IEEE International Workshop on Signal Processing Advances in Wireless Communications, pages 580-584, Stockholm, June 2015.
- A refined exposition of the offset-based beamforming technique that underlies the power loading algorithm
presented in this paper in this has been
developed.
- Adaptations of the ideas in the paper to the case of "Massive MIMO" systems was presented
at the Asilomar Conference in 2016. A discussion of that paper is available here.
- Some of the ideas in this paper were used in the development of
robust beamforming techniques for the multi-cell downlink here.
Last update: October 2017.
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Tim Davidson
(davidson@mcmaster.ca).