Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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A Route Establishment Scheme for Multi-route Coding in Multihop Cellular Networks Reviewed

H. Okada, H. Imai, T. Yamazato, M. Katayama, K. Mase

Academy Publisher Journal of Netowkrs, vol.3, no.7, pp.34-40 Vol. 3 ( 7 ) page： 34-40 2008.7

Language：English Publishing type：Research paper (scientific journal)

Since the network topology in multihop cellular networks is flexible, multiple routes from a user station to a base station can be established. To reduce packet reception errors of wireless links, a multi-route coding scheme was proposed. An important issue of the multi-route coding is to develop an efficient route establishment scheme. In this paper, we propose a route establishment scheme for multi-route coding in multihop cellular networks. Our proposed scheme consists of a route selection method based on the bit error rate of each wireless link and a hybrid-type multiple-tree routing protocol. We evaluate the performance of our proposed scheme by a computer simulation and show the resulting improvement in the packet error.

相関のある情報源の分散符号化・統合復号法のEXIT解析

小林健太郎，山里敬也，片山正昭

第4回無線分散ネットワークに関するワークショップ page： - 2008.6

A modulation scheme for a cognitive radio system to overlay on a secondary user Reviewed

NAGANAWA Jun, YAMAZATO Takaya, KATAYAMA Masaaki

IEICE technical report Vol. 108 ( 62 ) page： 5 - 10 2008.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

As an answer to increasing demands for frequency spectrum, secondary spectrum licensing, in which a secondary wireless system overlays on the frequency band of an existing primary system, is taking attention. In overlay communications, the secondary system is demanded not to be a cause of performance degradation of the primary system, while the primary system does not considers the secondary system. This manuscript proposes a modulation scheme for such a secondary system. In the proposed scheme, the secondary system modifies its transmitting signal parameters adapting channel states and transmitted signal of the primary system. This set of reference information is also used at the receiver of the secondary system. We derive the symbol error rates of both the systems analytically, and show that it is possble to realize the communication of the secondary system with the same quality as the primary system, which has any degradation by the signal of the secondary system.

CiNii Research

Spatial Diversity Scheme with Multiple-Transmit/Receive Antennas and Relay Terminals for Reliable Wireless Control Reviewed Open Access

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J91-B ( 5 ) page： 585-594 2008.5

Language：Japanese Publishing type：Research paper (scientific journal)

In this manuscript, a communication system for wireless control of industrial machines in indoor environment is discussed. In order to combat indoor fading and shadowing, an STBC cooperative relaying scheme, which uses multiple transmit and receive antennas together with multiple relay terminals, is introduced. In the proposed scheme each relay terminal transmits all STBC branch-signals with random phase rotations, and no exchange of information between the relay terminals is required to achieve high diversity order. In numerical evaluations, the proposed scheme is compared with conventional deterministic signal assignment or random branch selection schemes using average and outage probability of the frame-error rate as performance measures. As a result, the impact of the random phase rotations is clarified.

Open Access

A modulation scheme for a cognitive radio system to overlay on a secondary user

Jun Naganawa, Takaya Yamazato, Masaaki Katayama

Technical Report of IEICE Vol. SR2008-2 page： - 2008.5

Language：Japanese

As an answer to increasing demands for frequency spectrum, secondary spe ctrum licensing, in which a secondary wireless system overlays on the fr equency band of an existing primary system, is taking attention. In ove rlay communications, the secondary system is demanded not to be a cause of performance degradation of the primary system, while the primary syst em does not considers the secondary system. This manuscript proposes a modulation scheme for such a secondary system . In the proposed scheme, the secondary system modifies its transmitting signal parameters adapting channel states and transmitted signal of the primary system. This set of reference information is also used at the r eceiver of the secondary system. We derive the symbol error rates of both the systems analytically, and s how that it is possble to realize the communication of the secondary sys tem with the same quality as the primary system, which has any degradati on by the signal of the secondary system.

Spatial Diversity Scheme with Multiple-Transmit/Receive Antennas and Relay Terminals for Reliable Wireless Control Reviewed Open Access

R. Uchida, H. Okada, T. Yamazato, M. Katayama

IEICE Transactions on Communications Vol. J91-B ( 5 ) page： 585-594 - 594 2008.5

Measurement of Narrowband Channel Characteristics in Single-Phase Three-Wire Indoor Power-Line Channels Reviewed

Y. Sugiura, T. Yamazato, M. Katayama

IEEE International Symposium on Power Line Communications and Its Applications page： - 2008.4

Language：English

This manuscript reports the measurement results of narrowband signal propagation of PLC channels. In Japan, in-house wiring is single-phase three-wire, and each branch between an outlet of 100V and the panel board is connected to one of two live conductors and the neutral. Thus a pair of outlets can be classified into three types: connected to different live conductors, connected to the same live conductors by different branches from the panel board, and on the same branch to the same live conductor. It is confirmed that the results of the measurements can be classified by these three types of paths. The results show that frequency responses of narrowband PLC channels are relatively smooth, compared with that of wideband PLC. It is also found that propagation loss in lower frequency range is larger than in higher frequency range. The time independence of narrowband PLC channels are confirmed when no electric appliance is connected to the same live conductor.

A-17-12 CDMA Slotted ALOHA Systems with Successive Interference Cancellation for Inter-Vehicle Communications(A-17. ITS) Reviewed

Sakata Atsunori, Yamazato Takaya, Okada Hiraku, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2008 page： 323 2008.3

A-5-18 Adaptive modulation for power-line communications with nonwhite and cyclostationary noise Reviewed

Sawada Naoya, Yamazato Takaya, Katayama Masaaki

Proceedings of the IEICE General Conference Vol. 2008 page： 145 2008.3

A-2-35 Noncoherent Communication Systems using Chaotic Sequence with Many Biased Values Reviewed

ARAI Shintaro, NISHIO Yoshifumi, YAMAZATO Takaya

Proceedings of the IEICE General Conference Vol. 2008 page： 74 2008.3

Introduction of Fractional Frequency Reuse and Fast Retrial Algorithm for uplink of Multi-Cell OFDMA s-ALOHA systems

K. Kimura T. Yamazato, M. Katayama