Tsuyoshi Kogawa

Zero-Watt Networked Standby: Development and Evaluation of a Home A/V Network System

Energy conservation is an important global issue. Home is the third largest energy consumer, and 10% of the home energy is standby power of home appliances. The proliferation of home networks increases the standby power. The conventional technologies for low networked standby power such as WoL require continuous AC power, as much as 0.5 watts, to monitor wake-up signals. The large portion of the consumed power is due to the power loss in an AC-DC converter. Moreover, the technologies are applicable only to the specific network types such as Ethernet and IEEE802.11. We propose a solution to reduce the networked standby power down to zero virtually, regardless of the network type. For monitoring wake-up signals, the solution utilizes the precharged power in an ultra capacitor without using AC power supply almost all the time. In order to realize this idea, the solution also utilizes unique and simple protocol dedicated only to the networked standby /wake-up functionality. This protocolenables the monitoring circuit to consume very small power enough for the capacitor to supply. The networked standby/wake-up functionality is easily combined with any conventional network application protocol by protocol address mapping. As one realization example of our solution, we implemented an experimental system which is integrated with an ultra low power wireless signal receiver and extended UPnP protocol. The system evaluation showed that our solution achieves the zero-watt networked standby while keeping network functionalities. Moreover, the analysis of the results shows that the practical networked standby power is one seventeenth of the conventional technologies in usual usage. This corresponds to 1.11 kg-CO2 emission reduction per year per product.

Digital Baseband IC Design of OFDM PHY for a 60GHz Proximity Communication System

This paper presents a digital baseband IC design based on OFDM PHY for a 60GHz proximity communication system. We propose a low computational complexity OFDM demodulator with a carrier frequency offset estimation method in polar coordinates suitable for high-speed parallel architecture. The proposed architecture is implemented in 65nm CMOS technology, and is experimentally verified to achieve the PHY data rate above 2.2Gbps. The digital baseband IC includes a complete functionality of OFDM transceiver with error correcting codecs and MAC.

Low power consumption wireless wake-up module controlling AC power supply at household appliances

In this paper, we propose a wireless wake-up module controlling AC power supply to reduce power consumption at household electric appliances. The module is mainly composed of an Rx antenna, a wake-up IC, a microcontroller, an internal AC-DC converter, and two relays. The total current consumption of the module is about 15uA. The current consumption is around 1/300 that of a conventional module owing to the use of our developed low-power wake-up IC and the microcontroller with deep-sleep mode. The communication distance achieves 35m with output power of 18.3dBm under line-of-sight propagation.

OFDM WLAN system utilizing smart antenna DBF-IC for mobile terminal

The work presents a high throughput (over 20 Mbps) IEEE 802.11a wireless local area network (WLAN) system applicable to wireless TV and AV (audio-video). Multipath fading deteriorates the system throughput and its service area. A popular measure to overcome multipath fading has been a smart antenna at an access point (AP). However, this measure does not work well for the IEEE standard. The MAC layer standard requires every mobile terminal (MT) to receive all signals from the AP, and every MT cannot necessarily receive them from an AP with a smart antenna. We have developed a high throughput IEEE 802.11a WLAN system which provides each MT with a smart antenna, instead. This system makes it possible for each MT to listen to all signals from the AP and not to suffer from multipath fading. The digital beam forming IC (DBF-IC) we have developed for the system improves the received signal SNR and compensates the distortion due to frequency-selective fading. Actual system measurements with this IC show that the service area expands to double that of the conventional system with omni antenna.

Zero-watt Networked Standby: Reducing Power Consumption of Home A/V Network Systems

Energy conservation is an important global issue. The home is the third largest energy consumer, and 10% of the home energy use is standby power of home appliances. The proliferation of home networks increases the standby power. The conventional technologies for low networked standby power such as WoL require continuous AC power, as much as 0.5 watts, to monitor wake-up signals. A large portion of the consumed power is due to the power loss in the AC-DC converter. Moreover, the technologies are applicable only to the specific network types such as Ethernet and IEEE802.11. We propose a solution to reduce the networked standby power down to zero virtually, regardless of the network type. For monitoring wake-up signals, the solution utilizes the pre-charged power in an ultra capacitor without using the AC power supply for almost all the time. In order to realize this idea, the solution also utilizes a unique and simple protocol dedicated only to the networked standby/wake-up functionality. This protocol enables the monitoring circuit to consume a very small amount of power, small enough for the capacitor to supply. The networked standby/wake-up functionality is easily combined with any conventional network application protocol by protocol address mapping. As one realization example of our solution, we implemented an experimental home A/V system which is integrated with an ultra low power wireless signal receiver and extended UPnP protocol. The system evaluation showed that our solution achieves the zero-watt networked standby while keeping network functionalities. Moreover, the analysis of the results based on a statistical survey shows that the practical networked standby power is 30 mW when our solution is applied to a TV system, which corresponds to one seventeenth of a conventional technology, WoL. It means that our solution improves power consumption by 22% which corresponds to 1.11 kg-CO2 emission reduction per year per product.