Scheduling of multi-antenna broadcast systems with heterogeneous users
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Author(s)
Borst, Sem
Whiting, Phil
Modiano, Eytan H
Jagannathan, Krishna Prasanna
Date Issued
September 2007
Journal
IEEE Journal on Selected Areas in Communications
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Citation
Jagannathan, Krishna, Sem Borst, Phil Whiting, and Eytan Modiano. “Scheduling of Multi-Antenna Broadcast Systems with Heterogeneous Users.” IEEE Journal on Selected Areas in Communications 25, no. 7 (September 2007): 1424–1434.
Version
Author's final manuscript
Abstract
We study the problem of efficiently scheduling users in a Gaussian broadcast channel with M transmit antennas and K independent receivers, each with a single antenna. We first focus on a scenario with two transmit antennas and statistically identical users, and analyze the gap between the full sum capacity and the rate that can be achieved by transmitting to a suitably selected pair of users. In particular, we consider a scheme that picks the user with the largest channel gain, and selects a second user from the next L - 1 strongest ones to form the best pair, taking channel orientations into account as well. We prove that the expected rate gap converges to 1/(L- 1) nats/symbol when the total number of users K tends to infinity. Allowing L to increase with K, it may be deduced that transmitting to a properly chosen pair of users is asymptotically optimal, while considerably reducing the feedback overhead and scheduling complexity. Next, we tackle the problem of maximizing a weighted sum rate in a scenario with heterogeneous user characteristics. We establish a novel upper bound for the weighted sum capacity, which we then use to show that the maximum expected weighted sum rate can be asymptotically achieved by transmitting to a suitably selected subset of at most MC users, where C denotes the number of distinct user classes. Numerical experiments indicate that the asymptotic results are remarkably accurate and that the proposed schemes operate close to absolute performance bounds, even for a moderate number of users.
MIT Department
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
Massachusetts Institute of Technology. Laboratory for Information and Decision Systems
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1109/JSAC.2007.070915
