Filter Design for IBI Suppression in OFDM Based Filter-and-Forward Relay Beamforming

Satoshi NAGAI  Teruyuki MIYAJIMA  

IEICE TRANSACTIONS on Communications   Vol.E99-B   No.9   pp.2072-2080
Publication Date: 2016/09/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBP3470
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
OFDM,  filter-and-forward,  inter-block interference,  time-domain equalizer,  second order statistics,  

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In this paper, we consider filter-and-forward relay beamforming using orthogonal frequency-division multiplexing (OFDM) in the presence of inter-block interference (IBI). We propose a filter design method based on a constrained max-min problem, which aims to suppress IBI and also avoid deep nulls in the frequency domain. It is shown that IBI can be suppressed completely owing to the employment of beamforming with multiple relays or multiple receive antennas at each relay when perfect channel state information (CSI) is available. In addition, we modify the proposed method to cover the case where only the partial CSI for relay-receiver channels is available. Numerical simulation results show that the proposed method significantly improves the performance as the number of relays and antennas increases due to spatial diversity, and the modified method can make use of the channel correlation to improve the performance.