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Mathematical Problems in Engineering
Volume 2015, Article ID 892757, 6 pages
Research Article

Amplify-and-Forward Distributed Beamforming with Local CSI in the Presence of Interferences

1Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
2Broadcasting & Telecommunications Media Research Laboratory, ETRI, Daejeon 305-700, Republic of Korea
3Department of Information & Communication Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 771-873, Republic of Korea
4School of Computer Science, University of Seoul, Seoul 130-743, Republic of Korea
5Department of Computer Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia

Received 13 July 2015; Revised 18 November 2015; Accepted 1 December 2015

Academic Editor: Aline Roumy

Copyright © 2015 Jung-Bin Kim et al. 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.


This paper introduces an optimum amplify-and-forward (AF) distributed beamforming (DBF) in the presence of cochannel interference (CCI) when only local channel-state information (CSI) is available at each relay. It is shown that the proposed DBF closely achieves the performance obtained with global CSI when interference power toward relays is small or there are a large number of interferers but greatly reduces the complexity and overhead. The proposed DBF provides significant improvements over the conventional DBF designed without considering CCI at the cost of slightly increased complexity and overhead and achieves the capacity scaling of through relays, where corresponds to the maximal capacity scaling when there is no CCI.