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ABSTRACT: In this paper, the effect of time difference of arrival (TDoA) is investigated for distributed nodes in OFDMA-based wireless mesh networks (WMNs). In order to minimize the interferences caused by TDoA in WMNs, the optimal starting point of the FFT window at the receiver side of a node is derived by maximizing the effective SINR for each subcarrier. Also, a signal detection technique, called two dimensional ordered successive interference cancellation (TD-OSIC), is proposed for WMNs with TDoAs. It was shown via simulation that the proposed technique can achieve effective SINR and BER performances similar to the ideal case (no TDoA), even in WMNs with large TDoAs.
Communications (ICC), 2011 IEEE International Conference on; 07/2011
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Proceedings of the 73rd IEEE Vehicular Technology Conference, VTC Spring 2011, 15-18 May 2011, Budapest, Hungary; 01/2011
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ABSTRACT: In this correspondence, an efficient receive-diversity-combining technique is proposed for single-carrier frequency-division multiple access (SC-FDMA)-based cooperative relay systems when discrete Fourier transform (DFT) spreading sizes for mobile stations and relay stations are different. The proposed technique is composed of an adjustment block for the DFT spreading size, a phase rotation block, a resource reallocation block, a channel phase compensation block, a receive-diversity-combining block, a channel gain compensation block, and a resource de-allocation block. The proposed technique is shown to provide a high diversity gain in multipath channel environments with a relatively small computational complexity.
IEEE Transactions on Vehicular Technology 11/2010; · 1.92 Impact Factor
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IEICE Transactions. 01/2010; 93-B:2195-2198.
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ABSTRACT: In this paper, two receive diversity combining techniques are proposed for cooperative relay systems based on single-carrier frequency division multiple access (SC-FDMA) when DFT spreading sizes for a mobile station (MS) and relay station (RS) are different. A simplifled-MRC (S-MRC) technique performs diversity combining in the time-domain by using the estimated channel weights and initial estimates obtained by SC-FDMA signal detector. An interference rejection-MRC (IRMRC) technique performs diversity combining in the frequencydomain by adjusting DFT spreading size at the receiver. It is shown by computer simulation that the proposed receive combining techniques achieve a significant diversity gain over the conventional ones.
Vehicular Technology Conference Fall (VTC 2009-Fall), 2009 IEEE 70th; 10/2009
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Proceedings of the IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2009, 13-16 September 2009, Tokyo, Japan; 01/2009
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IEICE Transactions. 01/2009; 92-B:2972-2975.
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IEICE Transactions. 01/2009; 92-B:2492-2495.
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Proceedings of the 70th IEEE Vehicular Technology Conference, VTC Fall 2009, 20-23 September 2009, Anchorage, Alaska, USA; 01/2009
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IEICE Transactions. 01/2009; 92-B:2542-2545.
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Proceedings of the IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2009, 13-16 September 2009, Tokyo, Japan; 01/2009
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ABSTRACT: In this paper, a new handover procedure for OFDM-based multi-hop relay systems is proposed to reduce handover overhead by distinguishing an inter-cell handover event from an intra-cell handover event at the level of the physical layer using a preamble with a hierarchical design. A subcell ID concept that identifies RS in a cell is proposed in the hierarchical design that works in conjunction with the existing cell ID that identifies BS. The proposed handover procedure can simplify the scanning procedure and skip/simplify the network re-entry procedure, resulting in a significant reduction of handover overhead.
Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on; 10/2008
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ABSTRACT: In this paper, an iterative decoding technique for cooperative space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) systems is proposed to mitigate the intercarrier interference (ICI) caused by multiple carrier frequency offsets (CFOs) in cooperative transmission. The proposed iterative decoding technique is shown to mitigate the noise enhancement effect on the STBC-OFDM signals caused by multiple CFOs, and be effective in reducing ICI especially when the system has a large FFT size and a large multiple CFOs.
Personal, Indoor and Mobile Radio Communications, 2007. PIMRC 2007. IEEE 18th International Symposium on; 10/2007
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ABSTRACT: In this paper, the effect of a propagation delay resulting from the use of an OFDM system with a transparent mobile multi-hop relay (MMR) is initially analyzed. Additionally, a channel estimation technique for the OFDM system with throughput enhancement (TE) MMR or cooperative MMR is proposed. Secondly, the effect of a Doppler shift caused by a mobile MS is analyzed and a compensation technique for the carrier frequency offset (CFO) in the OFDM system with TE MMR is proposed.
Vehicular Technology Conference, 2007. VTC2007-Spring. IEEE 65th; 05/2007
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IEICE Transactions. 01/2007; 90-B:1555-1558.
