Shinsuke Takaoka

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A very high-speed wireless access of 100Mbps to 1Gbps is required for the 4th generation (4G) mobile communications systems. However, for such high-speed data transmissions the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. A promising wireless access technique that can overcome the channel(More)
SUMMARY Pilot-aided adaptive prediction channel estimation is proposed for coherent detection in a frequency-nonselective fading channel. It is an extension of the conventional weighted multi-slot averaging (WMSA) channel estimation and consists of 3 steps. A block of N p pilot symbols is periodically transmitted, each pilot block being followed by N d data(More)
For alleviating the high peak-to-average power ratio (PAPR) problem of orthogonal frequency division multiplexing (OFDM) while improving the bit error rate (BER) performance, the OFDM combined with time division multiplexing (TDM) using frequency-domain equalization (FDE) was recently proposed. In this paper, the theoretical BER analysis of the OFDM/TDM in(More)
SUMMARY Recently, multi-carrier code division multiple access (MC-CDMA) has been attracting much attention for the broadband wireless access in the next generation mobile communications systems. In the case of uplink transmissions, the orthogonality among users' signals is lost since each user's signal goes through different fading channel and hence,(More)
One of the main problems of orthogonal frequency division multiplexing (OFDM) is high peak-to-average power ratio (PAPR). In this paper, a novel approach to alleviate the PAPR problem of OFDM is presented. A generalized OFDM (GOFDM) with frequency-domain equalization (FDE) is proposed. Various FDE techniques based on zero forcing (ZF), maximum ratio(More)
SUMMARY Similar to direct sequence code division multiple access (DS-CDMA), site diversity can be applied to a multicarrier-CDMA (MC-CDMA) cellular system to improve the bit error rate (BER) performance for a user with weak received signal power, thus resulting in an increased link capacity. In this paper, the downlink site diversity reception using(More)
Orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (TDM), called OFDM/TDM, can overcome the high peak-to-average-power ratio (PAPR) problem of the conventional OFDM. Its bit error rate (BER) performance in a frequency-selective fading channel can be significantly improved by the use of frequency-domain equalization(More)
SUMMARY The objective of this paper is to develop the theoretical foundation to the pilot-assisted channel estimation using delay-time domain windowing for the coherent detection of OFDM signals. The pilot-assisted channel estimation using delay-time domain windowing is jointly used with polynomial interpolation, decision feedback and Wiener filter. A(More)