A Linear Combining Scheme to Suppress Interference in Multiple Relay Systems

Ahmet Ihsan CANBOLAT  Kazuhiko FUKAWA  

IEICE TRANSACTIONS on Communications   Vol.E99-B    No.8    pp.1867-1873
Publication Date: 2016/08/01
Publicized: 2016/02/17
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2016EBP3016
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
wireless communications,  multiple relay,  linear combining,  MMSE,  RLS,  

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This paper proposes an interference suppression scheme based on linear combining for multiple relay systems. Interference from base stations and relays in neighboring cells degrades the bit error rate (BER) performance of mobile stations (MSs) near cell boundaries. To suppress such interference for half-duplex relay systems, the proposed scheme linearly combines received signals of the first and second phases at MS. Without channel state information (CSI) feedback, weight coefficients for the linear combining are estimated by the recursive least-squares (RLS) algorithm, which requires only information on preamble symbols of the target MS. Computer simulations of orthogonal frequency-division multiplexing (OFDM) transmission under two-cell and frequency selective fading conditions are conducted. It is demonstrated that the RLS-based linear combining with decision directed estimation is superior to the RLS-based linear combining using only the preamble and can outperform the minimum mean-squared error (MMSE) combining with estimated CSI when the number of preamble symbols is two and four that correspond to the minimum requirements for MMSE and RLS, respectively.