Tetsu Koyama - Academia.edu (original) (raw)

Uploads

Papers by Tetsu Koyama

Research paper thumbnail of FAM 17.3: An ISDN Echo-Cancelling Transceiver Chip for 2810 Coded U-Interface

Research paper thumbnail of A multi-dimensional equalizer for Gigabit Ethernet

ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)

The insatiable demand for bandwidth in LAN applications has motivated the evolution of high-speed... more The insatiable demand for bandwidth in LAN applications has motivated the evolution of high-speed 1000BASE-T Ethernet from its predecessors, Fast Ethernet 100BASE-T and 10BASE-T. We report on a 4-dimensional equalizer and far-end crosstalk (FEXT) canceller (4D-EQLFXC) that has been investigated and found to be an efficient way to manage the remaining channel impairments by performing channel equalization and 4-channel FEXT cancellation in a single operation.

Research paper thumbnail of An Applicability Study of ADSL in Japanese Subscriber Lines

IEEJ Transactions on Electronics, Information and Systems, 1998

Research paper thumbnail of FSK with continuous phase and continuous slope at bit transitions

Research paper thumbnail of Magnetic transmission devices using the edge-guided mode of propagation

Research paper thumbnail of DC termination circuit for subscriber cables

Research paper thumbnail of Echo canceller for two-wire full duplex digital data transmission

Research paper thumbnail of Four dimensional equalizer and far-end cross talk canceler in Gigabit Ethernet signals

Research paper thumbnail of Echo canceller system suitable for a 2B1Q transmission code

Research paper thumbnail of Optimization of xDSL transmission systems

1999 IEEE International Conference on Communications (Cat. No. 99CH36311)

xDSL (digital subscriber line) is a group of technologies for transmitting high-speed digital sig... more xDSL (digital subscriber line) is a group of technologies for transmitting high-speed digital signals over existing metallic cables. xDSL was originally studied in the USA. These technologies have spread to other areas of the world, including Europe and Asia. In this process of introducing this technology to the different areas, several new local but critical problems have emerged, due to the local system and cable situations. In Japan, TCM (time compressed multiplex)-ISDN is widely used. This ISDN causes periodic crosstalk noise of far end cross-talk (FEXT) and near end cross-talk (NEXT) to xDSL. For the optimization of the transmission performance to this type of noise, it is efficient to use different bit assignments corresponding to the FEXT period and NEXT period. NEC has proposed a solution of the optimization for ADSL (asymmetric DSL) transmission under the TCM-ISDN crosstalk noise environment. We have compared the following transmission methods, the existing ANSI ADSL, dual bitmap (DBM)-ADSL, single bitmap (SBM)-ADSL and TCM-ADSL, with some simulation results. This shows that the performance of ANSI ADSL is greatly degraded by the ISDN crosstalk disturbance, and DBM-ADSL improves the performance significantly. SBM and TCM-ADSL also have better performances in a long reach with small modifications. The study results are explained.

Research paper thumbnail of Reflection Problems in a Ferrite Stripline

IEEE Transactions on Microwave Theory and Techniques, 1976

ABSTRACT

Research paper thumbnail of An ISDN Subscriber Loop Transmission System Based on Echo Cancellation Technique

IEEE Journal on Selected Areas in Communications, 1986

This paper proposes an ISDN subscriber loop transmission system based on an echo cancellation tec... more This paper proposes an ISDN subscriber loop transmission system based on an echo cancellation technique which fully supports the CCITT recommended basic interface for ISDN, i.e., B + B + D over metallic cables. System design considerations of cable loss, crosstalk, impulsive noise, and system requirements such as power feeding on a call-by-call basis are discussed, and a transmission system is proposed. The proposed system is characterized by the use of a pew line code, named "modified biphase code." The use of this code with fixed line loss equalization and coherent detection achieves circuit simplification. A special adaptation algorithm is incorporated with the echo canceller that significantly reduces convergence time. Experimentalresults show satisfactory performance with respect to the residual echo and the bit error rate. Since the system requires only a simple nonadaptive circuit for analog portion, it is suitable for LSI implementation.

Research paper thumbnail of FAM 17.3: An ISDN Echo-Cancelling Transceiver Chip for 2810 Coded U-Interface

Research paper thumbnail of A multi-dimensional equalizer for Gigabit Ethernet

ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)

The insatiable demand for bandwidth in LAN applications has motivated the evolution of high-speed... more The insatiable demand for bandwidth in LAN applications has motivated the evolution of high-speed 1000BASE-T Ethernet from its predecessors, Fast Ethernet 100BASE-T and 10BASE-T. We report on a 4-dimensional equalizer and far-end crosstalk (FEXT) canceller (4D-EQLFXC) that has been investigated and found to be an efficient way to manage the remaining channel impairments by performing channel equalization and 4-channel FEXT cancellation in a single operation.

Research paper thumbnail of An Applicability Study of ADSL in Japanese Subscriber Lines

IEEJ Transactions on Electronics, Information and Systems, 1998

Research paper thumbnail of FSK with continuous phase and continuous slope at bit transitions

Research paper thumbnail of Magnetic transmission devices using the edge-guided mode of propagation

Research paper thumbnail of DC termination circuit for subscriber cables

Research paper thumbnail of Echo canceller for two-wire full duplex digital data transmission

Research paper thumbnail of Four dimensional equalizer and far-end cross talk canceler in Gigabit Ethernet signals

Research paper thumbnail of Echo canceller system suitable for a 2B1Q transmission code

Research paper thumbnail of Optimization of xDSL transmission systems

1999 IEEE International Conference on Communications (Cat. No. 99CH36311)

xDSL (digital subscriber line) is a group of technologies for transmitting high-speed digital sig... more xDSL (digital subscriber line) is a group of technologies for transmitting high-speed digital signals over existing metallic cables. xDSL was originally studied in the USA. These technologies have spread to other areas of the world, including Europe and Asia. In this process of introducing this technology to the different areas, several new local but critical problems have emerged, due to the local system and cable situations. In Japan, TCM (time compressed multiplex)-ISDN is widely used. This ISDN causes periodic crosstalk noise of far end cross-talk (FEXT) and near end cross-talk (NEXT) to xDSL. For the optimization of the transmission performance to this type of noise, it is efficient to use different bit assignments corresponding to the FEXT period and NEXT period. NEC has proposed a solution of the optimization for ADSL (asymmetric DSL) transmission under the TCM-ISDN crosstalk noise environment. We have compared the following transmission methods, the existing ANSI ADSL, dual bitmap (DBM)-ADSL, single bitmap (SBM)-ADSL and TCM-ADSL, with some simulation results. This shows that the performance of ANSI ADSL is greatly degraded by the ISDN crosstalk disturbance, and DBM-ADSL improves the performance significantly. SBM and TCM-ADSL also have better performances in a long reach with small modifications. The study results are explained.

Research paper thumbnail of Reflection Problems in a Ferrite Stripline

IEEE Transactions on Microwave Theory and Techniques, 1976

ABSTRACT

Research paper thumbnail of An ISDN Subscriber Loop Transmission System Based on Echo Cancellation Technique

IEEE Journal on Selected Areas in Communications, 1986

This paper proposes an ISDN subscriber loop transmission system based on an echo cancellation tec... more This paper proposes an ISDN subscriber loop transmission system based on an echo cancellation technique which fully supports the CCITT recommended basic interface for ISDN, i.e., B + B + D over metallic cables. System design considerations of cable loss, crosstalk, impulsive noise, and system requirements such as power feeding on a call-by-call basis are discussed, and a transmission system is proposed. The proposed system is characterized by the use of a pew line code, named "modified biphase code." The use of this code with fixed line loss equalization and coherent detection achieves circuit simplification. A special adaptation algorithm is incorporated with the echo canceller that significantly reduces convergence time. Experimentalresults show satisfactory performance with respect to the residual echo and the bit error rate. Since the system requires only a simple nonadaptive circuit for analog portion, it is suitable for LSI implementation.

Log In