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International Journal of Digital Multimedia Broadcasting
Volume 2017 (2017), Article ID 1320689, 8 pages
Research Article

Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

College of Electronic Engineering, Naval University of Engineering, Wuhan 430033, China

Correspondence should be addressed to Gaoqi Dou

Received 12 April 2017; Revised 18 September 2017; Accepted 1 October 2017; Published 8 November 2017

Academic Editor: Wanggen Wan

Copyright © 2017 Xianwen He 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.


We consider the training design and channel estimation in the amplify-and-forward (AF) diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM) mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI) of second-hop link due to the multiaccess interference (MAI) and cooperative data interference (CDI). To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ) relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.