Shigemi Ishida

A Novel Wireless Wake-Up Mechanism for Energy-Efficient Ubiquitous Networks

Excessive power consumption is a major problem in wireless communication. This is particularly true in ubiquitous computing environments, since wireless devices consume a considerable amount of energy in idle listening. Wake-up wireless communication technology is a promising candidate for reducing power consumption during idle listening. To realize wake-up wireless communication, this paper proposes a novel ID matching mechanism that uses a Bloom filter. This paper describes the design and implementation of a wireless wake-up module that uses this ID matching mechanism. Simulation results reveal that the wake-up module consumes only 12.4 muW while idle listening, and that employing this Bloom-filter-based approach eliminates 99.95 % of power consumption in our application scenarios.

WiFi AP-RSS Monitoring Using Sensor Nodes toward Anchor-Free Sensor Localization

Sensor localization is one of the big problems when building large scale indoor sensor networks since GPS is unavailable in indoor environments. Many indoor localization systems have been proposed to tackle the sensor localization problem, yet user cooperation or many anchor nodes are required. In this paper, we propose a sensor localization system using WiFi APs as anchors. WiFi APs are largely installed in indoor environments and are managed by a network system manager. Using WiFi APs as anchors, we can localize sensor nodes without newly deployed anchor nodes. As a first step of our sensor localization system, this paper presents a WiFi AP-RSS monitoring system using sensor nodes. Sensor nodes are equipped with IEEE802.15.4 (ZigBee) modules, which cannot demodulate WiFi (IEEE802.11) signals. We therefore developed a cross-technology signal extraction scheme on sensor nodes. We herein describe the design and implementation of our AP-RSS monitoring system. The experimental evaluations show that our AP-RSS monitoring system successfully retrieves AP-RSS with an average error of 1.26dB.

AP-assisted CTS-blocking for WiFi-ZigBee Coexistence

WiFi interference is one of the big problems in ZigBee-based sensor networks. In this paper, we present a new WiFi-ZigBee coexistence scheme named AP-assisted CTS-blocking (AA CTS-blocking). The AA CTS-blocking uses an RTS/CTS (request to send, clear to send) mechanism to prevent WiFi transmissions during ZigBee communications. An RTS/CTS mechanism is defined in the IEEE 802.11 standard and is supported by off-the-shelf WiFi devices. We present the design and implementation of AA CTS-blocking utilizing an off-the-shelf WiFi device as it is. The experimental evaluations revealed that AA CTS-blocking reduced frame error rate (FER) by approximately 5% compared to an existing WiFi-ZigBee coexistence scheme.

Design of WiFi-AP operating channel estimation scheme for sensor node

Sensor localization is one of the big problems when building large scale indoor sensor networks because GPS (Global Positioning System) is unavailable in indoor environments. We are developing a sensor localization system using WiFi APs as anchors, which requires no anchor deployment. Because sensor nodes cannot demodulate WiFi signals, we have developed a cross-technology RSS (received signal strength) measurement scheme with an AP recognition scheme [1, 2]. In this paper, we present WiChest, a WiFi-AP operating channel estimation scheme to accurately measure AP-RSS on sensor nodes. AWiFi channel overlaps with four ZigBee channels. AP-RSS depends on a ZigBee channel in which a sensor node measures the RSS. Using WiChest, a sensor node automatically switches its channel based on an estimated AP channel prior to RSS measurement. We implemented WiChest using a MICAz sensor node. The experimental evaluations reveal that WiChest accurately estimates AP operating channels with an F-measure of 0.80.

Towards sustainable information infrastructure platform for smart mobility - Project overview

Smart mobility systems, which include Intelligent Transportation System (ITS) and smart energy systems, become more important. There is, however, lack of its platform studies. This paper proposes a sustainable information infrastructure project for smart mobility systems. The project pursues issues that establish an information infrastructure architecture and seamless development method chain for it. The project has mainly two features, (1) applying life-cycle-oriented methods, which are a cycle from system development to operations, to the real world, and (2) dealing with uncertainties when a system begins to be designed. This paper describes an overview of the project.

Proposal of separate channel fingerprinting using bluetooth low energy

BLE (Bluetooth Low Energy) based localization is a next candidate for indoor localization. In this paper, we propose a new BLE-based fingerprinting localization scheme that improves localization accuracy. BLE is a narrow band communication that is highly affected by frequency selective fading and channel gains. We employ channel-specific features to location fingerprint to improve localization accuracy. Current BLE standards provide no API to retrieve an advertising channel number. We therefore developed a separate channel advertising scheme to measure RSS (Received Signal Strength) on each advertising channel. To demonstrate the feasibility of the separate channel fingerprinting, we conducted initial evaluations. Experimental evaluations showed that the separate channel fingerprinting improves accuracy by approximately 12%.

Design of WiFi AP-RSS Monitoring System Using Sensor Nodes

Sensor localization is one of the big problems when building large scale indoor sensor networks because GPS is unavailable in indoor environments. In this paper, we propose a sensor localization system using WiFi APs as anchors. WiFi APs are largely installed in indoor environments and are managed by a network system manager. Using WiFi APs as anchors, we can localize sensor nodes with neither newly deployed anchor nodes nor user cooperation. As a first step of our sensor localization system, this paper presents a WiFi AP-RSS monitoring system using sensor nodes. Sensor nodes are equipped with ZigBee (IEEE 802.15.4) modules, which cannot demodulate WiFi (IEEE 802.11) signals. We therefore developed a cross-technology signal extraction scheme with an AP recognition scheme on sensor nodes. We herein describe the design and implementation of our AP-RSS monitoring system. The experimental evaluations demonstrated that the proposed AP-RSS monitoring system successfully recognized WiFi APs with detection errors less than 10%. We also confirmed that the proposed system monitored AP-RSS with an average error of 1.26dB.

Preambleless TDD/TDMA OFDM system for real-time wireless control networks

This paper presents a preambleless communication system to realize industrial wireless control networks (WCN) which are characterized by short payloads and strict real-time requirements. The reduction of the preamble is greatly beneficial for the real-time operation because the transmission time of preambles is longer than that of the short payloads. Our system is implemented on a software defined radio (SDR) platform using GNU Radio toolkit. Experiments show the packet error rate (PER) performance is close to that of the theoretical value in an AWGN (additive white Gaussian noise) environment. Demonstrations show the real-time remote control of inverted pendulums on this system.

Toward Sustainable Smart Mobility Information Infrastructure Platform: Project Overview

Smart mobility systems, which include Intelligent Transportation Systems (ITS) and smart energy ones, become more important. There is, however, lack of its platform studies. This paper proposes a sustainable information infrastructure project for smart mobility systems. The project pursues issues that establish an information infrastructure architecture and a seamless development method chain for it. The project has mainly two features: (1) applying life-cycle-oriented methods, which are a cycle from system development phase to operation phase. In addition, these methods are applied to real world applications, and (2) dealing with an uncertainty that occurs in system development upper phase. This paper describes an overview of the project.

Design and Initial Evaluation of Bluetooth Low Energy Separate Channel Fingerprinting

Bluetooth Low Energy (BLE) based localization is a next candidate for indoor localization. In this paper, we propose a new BLE-based fingerprinting localization scheme that improves localization accuracy. BLE is a narrow bandwidth communication that is highly affected by frequency selective fading. Frequency selective fading is mainly caused by multipaths between a transmitter and receiver, which are dependent on channels. We utilize channel specific features by separately measure received signal strength (RSS) on different channels to improve localization accuracy. BLE standards provide no API to retrieve channel information of incoming packets. We therefore developed a separate channel advertising scheme to separately measure RSS on different channels. To demonstrate the feasibility of the separate channel fingerprinting, we conducted preliminary experiments as well as initial evaluations. Experimental evaluations demonstrated that the separate channel fingerprinting improves localization accuracy by approximately 12%.