Teruaki Kitasuka

Wireless LAN based indoor positioning system WiPS and its simulation

The wireless LAN (Wi-Fi) infrastructure is widely used and many location-aware systems and services are researched. In this paper, wireless LAN based indoor positioning system (WiPS) is proposed. WiPS uses wireless LAN technology to measure the location of each mobile terminal. Mobile terminals equip only wireless LAN device to communicate and measure its location, so it can be made without any additional devices for location sensing. Existing wireless LAN based location systems measure the signal strength by only access points. On WiPS, each mobile terminal also measures the signal strength of neighboring terminals. Thereby WiPS can achieve more precise location estimation than existing systems, where there are many mobile terminals. We simulate the case that distance measurement has probabilistic error. The result shows improvement of accuracy in WiPS.

WiPS: Location and Motion Sensing Technique of IEEE 802.11 Devices

For increasing needs of positioning technology, easy and simple indoor positioning system is desired. Wireless LAN based positioning system is a major candidate of indoor positioning technology. Conventional WLAN based systems require high installation cost or long site calibration before use. In this paper, we describe the implementation of simple WLAN based indoor positioning system WiPS. WiPS uses RSSI between terminals to avoid site calibration. We perform an experiment called a flag game, in which the person raises and lowers the PDA held in each hand. WiPS determines each hand is up or down. As results of the experiment, WiPS detects the movement of PDA in 4.8 sec. on an average

Location estimation system using wireless ad-hoc network

Location aware computing is popular and location information has become more important before. Ubiquitous computing also needs location information. We propose a location estimation system using a multi-hop wireless ad-hoc network. The proposed system estimates the locations of mobile hosts, using distance between hosts and the locations of some special hosts which know each location by GPS or other devices. This system is designed as a client-server model. The server is called an accumulator host and calculates the locations of all hosts. We also describe an estimation algorithm running in the accumulator host.

UDSS: Sensor Device for Context Awareness in Home Network

Many appliances include computers, such as home electrical appliances, A/V appliances and cellular phones. If these computers can obtain the user context by themselves, they will be able to automatically offer suitable services to the user appropriate for the user context. The appliances must use sensors to recognise the user context. Here, we developed a sensor device that provides sensing function to appliances to allow recognition of the user context. The sensor device is called UDSS (Ubiquitous Data Source Server). This sensor device has five sensors: temperature, humidity, sound, light and pyroelectric infrared sensors. UDSS provides the current sensed value of each sensor. In addition, UDSS can notify the changes in the pyroelectric infrared sensor value to subscribing appliances. These functions are implemented using UPnP, which allows the appliances in a home network to use this sensor device easily.

Mobility based algorithm for mobile ad-hoc network

In ad-hoc on-demand routing algorithm, when a route is broken a relay node must perform error transaction and the initiator must do rerouting to discover an alternate route. Many packets generated by these processes cause packet congestion and apply load on nodes. Those degrade network performance. It is important to construct a stable route when route discovery. In this paper, we use relative speeds among nodes as a measure of node mobility. Our routing algorithm chooses nodes of lower relative speed as relay nodes. As a result of our simulation, our proposing algorithm can reduce route breaks: 3.1 times smaller than DSR. And our proposing algorithm can deliver more packets than DSR: 18.5% higher rate.

Product Line Based Component Unification and Exploiting Unified Components in FORM

In this paper we propose product line based component unification to reuse works required for component unification such as combined tests, WCET estimation, etc. and properties produced by component unification such as documents, binaries etc. We perform a case study of the personal destination screen with personal identification and find that component unification is worth to consider in product line engineering. Moreover, we present a sketch of an algorithm, which we expect to use in product line engineering tools, to exploit candidate components to be unified for strategic reuse along the product line with the feature model diagram of FORM product line engineering.

Design and implementation of the Lambda μ-kernel based operating system for embedded systems

With large-scale embedded systems, improvement of development efficiency is one of the most important problems. In this paper, we design and implement an embedded operating system, called the Lambda operating system, which improves the maintainability and development efficiency of the operating system. The Lambda operating system employs micro-kernel architecture, which allows the operating system to be easily designed. In addition, we propose a method to improve operating system performance by reconstructing it in implementation. With the method, Lambda is implemented as monolithic kernel. The method allows the operating system to be quickly developed and gives high performance. This paper also shows that the method is useful through implementing a prototype of Lambda and its performance evaluation.