February 2013 Vol. 11 No. 2

View from the Top

• Kazutoshi Murao, President of NTT WEST

  

  Overview
  What strategies should be adopted to face the very severe conditions of the current telecommunications market? Kazutoshi Murao, President of NTT WEST, says that the NTT WEST Group must adopt a "one step forward" attitude to get back on the path to growth. We asked him about the future direction of NTT WEST and the strategies it needs to adopt.

Feature Articles: Circuit and Device Technologies for Extremely Low-power Consumption for Future Communications Systems

• Device Innovations toward the Green of Information and Communications Technology

  

  Abstract
  The recent growth in popularity of fiber-to-the-home (FTTH) services and mobile smartphones is resulting in an explosive increase in the volume of communications traffic, and this has led to a subsequent increase in the power consumed by network devices and terminals. In the Feature Articles in this issue, we give an overview of power-reducing and power-saving techniques to implement green information and communications technology, and we introduce technological developments NTT is working on that are designed to reduce the power consumption of network equipment.

• Low-power LSI Techniques for Next-generation FTTH System

  

  Abstract
  Demand for reduced power consumption of network devices is growing as Internet protocol traffic increases and fiber-to-the-home service penetration expands. This article describes our low-power-consumption technology developed for application to medium access control large-scale integrated circuits (LSIs) and analog front-end integrated circuits. Power saving is achieved with dynamic control according to the traffic state or link state, which reduces power consumption in LSIs and in entire network systems.

• Energy-saving Technique for High-speed Packet Forwarding LSIs

  

  Abstract
  Network traffic is increasing exponentially, and this requires packet forwarding circuits with higher capacity, which strengthens the demand for higher energy efficiency in these circuits. This article describes an energy-saving technique for high-speed packet forwarding circuits.

• Nanowatt Circuit Technology for an Ultrasmall Wireless Sensor Node with Energy Harvester

  

  Abstract
  This article describes an ultrasmall wireless sensor node (WSN) that is powered by an energy harvester. The small WSNs can be mounted on any kind of object without increasing their volume, and the energy harvester provides power without having to worry about battery life. However, it is difficult to achieve a WSN that is both ultrasmall and yet still has sufficient power: the smaller the energy harvester is, the less power it generates. We have developed two nanowatt circuit techniques to address this issue. One is a sensing circuit that converts signals with vibration energy. The other is a wireless circuit that uses a quick startup ring oscillator and pulse modulation with an intermittent-driving radio frequency circuit.

• Low-power-consumption Sensor Interface Terminal for Telemetry Applications

  

  Abstract
  We have developed a sensor interface terminal with low power consumption that enables various communication terminals to accommodate several sensors. In this article, we describe the concept of the interface terminal and the technologies applied to achieve low power consumption. We also give an overview of a prototype terminal and report the results of its demonstration in an actual environment.

• Vibrational Energy Harvesting with Microelectromechanical System Technology

  

  Abstract
  This article introduces a system for converting ambient vibrational energy to electrical energy using a microelectromechanical system (MEMS). A novel slit-and-slider structure is proposed as a way to miniaturize small sensor terminals. The results obtained with this system are expected to pave the way to designing and fabricating small vibrational energy harvesters.

• Integrated Silicon-based Optical Interconnect for Fast, Compact, Energy-efficient Electronic Circuit Systems

  

  Abstract
  The performance of electronic circuit systems is now reaching saturation because of restrictions on the bandwidth, integration density, and power consumption of electronic interface devices. In this article, we present high-density chip-to-chip optical interconnects based on silicon photonics technology, which has the potential to solve these critical problems.

Regular Article

• Mechanical Transfer of GaN-based Devices Using Layered Boron Nitride as a Release Layer

  

  Abstract
  Nitride semiconductors are the preferential choice in various device applications such as optoelectronics and high-power electronics. These gallium nitride (GaN)-based device structures can be grown on sapphire, silicon carbide, and silicon substrates, but not on large, flexible, and affordable substrates such as polycrystalline or amorphous substrates. This article reports our research results that demonstrate that hexagonal boron nitride (h-BN) can form a release layer that enables the mechanical transfer of GaNbased device structures onto foreign substrates. Aluminium (Al) GaN/GaN hetero-structures and indium (In)GaN/GaN multiple-quantum-well (MQW) structures grown on h-BN-buffered sapphire substrates, ranging in area from 25 mm² to 4 cm², were mechanically released from the host substrates and successfully transferred onto other substrates. The electroluminescence intensities from the transferred light-emitting diode (LED) were comparable to or higher than those from a conventional LED on a low-temperature AlN buffer layer, indicating that the MQW preserved its original quality after the transfer.

Global Standardization Activities

• Standardization Progress in Software Defined Networking/OpenFlow

  

  Abstract
  The concept of Software Defined Networking (SDN) has attracted attention recently from network carriers and service providers because of its potential to provide flexible/dynamic control and programmability in network topology and packet forwarding/processing functions. In this article, we briefly describe SDN and OpenFlow and discuss their standardization trends.

Practical Field Information about Telecommunication Technologies

• Case Study of Noise Faults Originating in Metallic Leased Lines and Countermeasure

  

  Abstract
  In this article, we introduce failure cases and a failure countermeasure for metallic leased lines. This is the fifteenth in a bimonthly series on the theme of practical field information on telecommunication technologies. This month's contribution is from the Net Interface Group, Technical Assistance and Support Center, Maintenance and Service Operations Department, Network Business Headquarters, NTT EAST.

External Awards

• External Awards