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)
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)
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 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)
Orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (TDM) can bridge the conventional OFDM and single carrier (SC) transmission by using minimum mean square error (MMSE) frequency-domain equalization (FDE). The channel frequency-selectivity can be exploited by MMSE-FDE to improve the bit error rate (BER) performance. A(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)
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)
Coherent rake reception of direct sequence code division multiple access (DS-CDMA) signals requires accurate channel estimation in a frequency-selective fading channel. This paper studies a code-multiplexed pilot-assisted frequency-domain channel estimation using FFT/IFFT, which has a good tracking capability against fast fading and can reduce the effect of(More)