Shogo Nakaya

A new design arrangement of transmission fiber dispersion for suppressing nonlinear degradation in long-distance optical transmission systems with optical repeater amplifiers

The invention of the erbium-doped fiber amplifier has opened the possibility of constructing long-distance optical transmission systems with 1.5-mm zero-dispersion wavelength shifted fibers. In such systems, nonlinear degradation due to four-wave mixing and self-phase modulation strictly limits the total span of systems and the length of the optical repeater spacing. There are proposals to use slightly normal group velocity dispersion fibers (D >

Programmable cell array using rewritable solid-electrolyte switch integrated in 90nm CMOS

Programmable devices such as SRAM-based FPGAs have the major challenges of power consumption and circuit area due to the excessive standby leakage current and the threshold voltage variation in highly scaled SRAM. Back-end-of-line (BEOL) device, which is integrated in the interconnect layers, is attractive for reducing the performance gap between FPGA and cell-based ASIC [1–4]. In this paper, we demonstrate the fundamental operations of a programmable cell array and a 32×32 crossbar switch using a nonvolatile and rewritable solid-electrolyte switch (nanobridge or NB). A 72% reduction in chip-area compared with that of a standard-cell-based design is achieved on a 90nm CMOS platform.

An arrangement of transmission-fiber dispersions for increasing the spacing between optical amplifiers in lumped repeater systems

A method for suppressing degradation due to nonlinearities in transmission fibers in lumped repeater systems is proposed. This method increases optical amplifier repeater spacing by setting a normal dispersion fiber as a transmission fiber, and by setting a 1.3- mu m zero-dispersion wavelength fiber as a dispersion compensator at the end in each repeater spacing so as to keep the total dispersion of the complete amplifier repeater spacing at around zero. Employing this method, a less than 1-dB power penalty, 10-Gb/s, 950-km transmission has been demonstrated, keeping the repeater spacings at 95 km and setting the repeater output power at 13 dBm.<<ETX>>

Adaptive sensing of ECG signals using R-R interval prediction

There is growing demand for systems consisting of tiny sensor nodes powered with small batteries that acquire electrocardiogram (ECG) data and wirelessly transmit the data to remote base stations or mobile phones continuously over a long period. Conserving electric power in the wireless sensor nodes (WSNs) is essential in such systems. Adaptive sensing is promising for this purpose since it can reduce the energy consumed not only for data transmission but also for sensing. However, the basic method of adaptive sensing, referred to here as “plain adaptive sensing,” is not suitable for ECG signals because it sometimes capture the R waves defectively. We introduce an improved adaptive sensing method for ECG signals by incorporating R-R interval prediction. Our method improves the characteristics of ECG compression and drastically reduces the total energy consumption of the WSNs.

A non-volatile reconfigurable offloader for wireless sensor nodes

Energy saving is currently one of the most important issues in the development of battery-powered wireless sensor nodes (WSNs). We have developed a non-volatile reconfigurable offioader for flexible and highly efficient processing on WSNs that uses NanoBridges (NBs), which are novel non-volatile and reprogrammable switching elements. Non-volatility is essential for the intermittent operation of WSNs due to the requirement of power-on without loading configuration data. We implemented a data compression algorithm on the offioader that reduces energy consumption during data transmission. Simulation results showed that the energy consumption on the offioader was 1121 of that on an ultra-low power cpu.