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International Journal of Antennas and Propagation
Volume 2012 (2012), Article ID 103501, 10 pages
Research Article

Interference-Based Decode and Forward Scheme Using Relay Nodes in Heterogeneous Networks

1Faculty of Engineering, Niigata University, Niigata-shi, Niigata 950-2181, Japan
2NTT DOCOMO, INC., 3-5 Hikari-no-oka, Yokosuka-shi, Kanagawa 239-8536, Japan

Received 1 June 2012; Revised 21 August 2012; Accepted 2 September 2012

Academic Editor: Ding-Bing Lin

Copyright © 2012 Kentaro Nishimori 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 proposes interference-based decode and forward scheme that utilizes relay stations (RSs). In Long-Term-Evolution (LTE-) Advanced, heterogeneous networks in which femto- and picocells are overlaid onto macrocells are extensively discussed. However, interference between macro- and pico(femto)cells arises due to their different transmit power levels. Unlike conventional cooperative transmission schemes, the RS decodes interference in the first transmit timing period and forwards it to the user equipment (UE) in the second period. Moreover, cooperative transmission can be achieved without stopping the transmission from the base station (BS) to UE when forwarding the interference from the RS to the UE by utilizing the fact that signal-to-noise power ratio (SNR) between the RS and UE is much greater than that between the BS and UE. The basic performance of the proposed method is shown based on computer simulation. Moreover, the interference temperature and shadowing effect are measured when considering the coexistence between macro- and femtocells, and the performance of the proposed method is verified using measured shadowing effect.