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  • Research Article
  • Open Access

Multicell Downlink Capacity with Coordinated Processing

  • 1Email author,
  • 2,
  • 3,
  • 3,
  • 3 and
  • 3
EURASIP Journal on Wireless Communications and Networking20082008:586878

  • Received: 31 July 2007
  • Accepted: 13 March 2008
  • Published:


We study the potential benefits of base-station (BS) cooperation for downlink transmission in multicell networks. Based on a modified Wyner-type model with users clustered at the cell-edges, we analyze the dirty-paper-coding (DPC) precoder and several linear precoding schemes, including cophasing, zero-forcing (ZF), and MMSE precoders. For the nonfading scenario with random phases, we obtain analytical performance expressions for each scheme. In particular, we characterize the high signal-to-noise ratio (SNR) performance gap between the DPC and ZF precoders in large networks, which indicates a singularity problem in certain network settings. Moreover, we demonstrate that the MMSE precoder does not completely resolve the singularity problem. However, by incorporating path gain fading, we numerically show that the singularity problem can be eased by linear precoding techniques aided with multiuser selection. By extending our network model to include cell-interior users, we determine the capacity regions of the two classes of users for various cooperative strategies. In addition to an outer bound and a baseline scheme, we also consider several locally cooperative transmission approaches. The resulting capacity regions show the tradeoff between the performance improvement and the requirement for BS cooperation, signal processing complexity, and channel state information at the transmitter (CSIT).


  • Channel State Information
  • Capacity Region
  • Singularity Problem
  • Cooperative Transmission
  • Downlink Transmission

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Authors’ Affiliations

Laboratory for Information and Decision Systems (LIDS), Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
Electrical Engineering and Computer Science Department, University of California, Berkeley, CA 94720-1770, USA
Corporate R & D Division, Qualcomm Incorporated, 5775 Morehouse Drive, San Diego, CA 92121, USA


© Sheng Jing 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.