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Open Access

Uplink SDMA with Limited Feedback: Throughput Scaling

  • Kaibin Huang1Email author,
  • Robert W. HeathJr.1 and
  • Jeffrey G. Andrews1
EURASIP Journal on Advances in Signal Processing20072008:479357

https://doi.org/10.1155/2008/479357

Received: 15 June 2007

Accepted: 23 October 2007

Published: 15 November 2007

Abstract

Combined space division multiple access (SDMA) and scheduling exploit both spatial multiplexing and multiuser diversity, increasing throughput significantly. Both SDMA and scheduling require feedback of multiuser channel sate information (CSI). This paper focuses on uplink SDMA with limited feedback, which refers to efficient techniques for CSI quantization and feedback. To quantify the throughput of uplink SDMA and derive design guidelines, the throughput scaling with system parameters is analyzed. The specific parameters considered include the numbers of users, antennas, and feedback bits. Furthermore, different SNR regimes and beamforming methods are considered. The derived throughput scaling laws are observed to change for different SNR regimes. For instance, the throughput scales logarithmically with the number of users in the high SNR regime but double logarithmically in the low SNR regime. The analysis of throughput scaling suggests guidelines for scheduling in uplink SDMA. For example, to maximize throughput scaling, scheduling should use the criterion of minimum quantization errors for the high SNR regime and maximum channel power for the low SNR regime.

Keywords

Quantization ErrorDesign GuidelinePublisher NoteChannel PowerSpace Division Multiple Access

Publisher note

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Authors’ Affiliations

(1)
Wireless Networking and Communications Group, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, USA

Copyright

© Kaibin Huang et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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