Hiroshi Sakakibara

Design and implementation of a socket-level bandwidth aggregation mechanism for wireless networks

This paper proposes a mechanism to aggregate bandwidth of multiple network interfaces on a computer. Recently one single computer entails multiple different wireless network interfaces, such as IEEE 802.11a/b/g/n, Bluetooth, WiMAX, and so on. They can be combined, and we can aquire broad bandwidth. We designed and developed a Socket-level Bandwidth Aggregation Mechanism (SBAM). SBAM can aggregate multiple interfaces on a computer to offer broad bandwidth. In addition, implementation in socket layer causes easy deployment and adaptation to existing environment. We evaluated SBAM under actual wireless network environments. SBAM offers broad bandwidth by utilizing various wireless devices on a computer while it avoids modification to existing environment.

uPackage: a package to enable do-it-yourself style ubiquitous services with daily objects

This paper explores a suitable service model for realizing domestic smart object applications and proposes a software and hardware package called uPackage to support this model. By attaching a tiny wireless sensor node to users belongings, users can augment the object digitally and take the object into various services such as status monitoring or preventing lost property. The system provided by uPackage supports users to install and manage such smart object services; it enables users to digitally associate sensor nodes with daily objects, manage the associated information and sensor data, and create various smart object applications without professional skills. Initial demonstration to children indicate that the service model provided by uPackage is easy understandable and increases users acceptance of the wireless sensor node technology.

PBN: A seamless network infrastructure of heterogeneous network nodes

Motivation The research and development of wireless sensor technology are active in recent years. One of the applied use of the sensors is to integrate into living environment for context-aware ubiquitous services. A construction of the service requires to seamlessly cooperate the heterogeneous networks, e.g., wireless sensor networks and TCP/IP networks. The seamless network infrastructure needs to cope with some types of heterogeneity of the network. We analyze the heterogeneity and classify the requirements for the seamless network infrastructure as the following four types of transparency. 1) Network transparency, which enables to communicate the heterogeneous network nodes each other. 2) Node location transparency, which enables sensor nodes placed apart communicate each other. 3) Data Format Transparency, which translates the data format heterogeneity between the heterogeneous network nodes. 4) Control protocol transparency, which enables to communicate sensor nodes leveraging heterogeneous service protocols. Lots of existing works [1] [2] focus on the same issues. Their proposition is to hide the heterogeneity by middleware. The middleware offers an efficient APIs for constructing a new ubiquitous service using heterogeneous network nodes. However, existing software cannot be run on the middleware because of the API difference. In addition, application developers need to learn new APIs to leverage the middleware. We present a Personal Belongings Network (PBN) mechanism, of which the design goal is to offer an seamless networking infrastructure enabling the existing software run on it, and to keep the application development cost low. To meet the goal, we focus on the requirement 1) and 2) for this paper. Since the PBN mechanism keeps the existing network environment, a collaboration with the mentioned existing works is easily possible.

A self configurable topology-aware network for smart materials

In this paper, we present an architecture to create extemporaneous networking on u-Texture. u-Texture is a tile shaped smart material which can be used to construct smart furnitures. Each u-Texture reacts according to what the entire smart furniture is shaped like. This reaction greatly affects the networking within a u-Texture. We therefore must allow dynamic arrangements within the network when a u-Texture is detached from or attached to another smart furniture. We present our tactics to implement such an self configurable topology-aware network to support applications executed on the entire smart furniture.

iPath: Achieving high-performance end-to-end paths for multi-homed mobile hosts

This work aims at building iPath - a path-selection system for multi-homed mobile hosts that assists vertical handoff. Unlike existing systems, iPath selects the access network interface for communications based on end-to-end path properties (e.g., available bandwidth, delay, packet loss rate, and jitter). iPath also adopts a new metric for handoff - “switching cost”, which is caused by the congestion control behavior of transport protocols when the mobile host changes its source or destination address. Handoff decision based on the switching cost prevents inappropriate handoff in terms of transmission performance and smoothness.

SmSCTP: A Fast Transport Layer Handover Method Using Single Wireless Interface

Many handover techniques in the Internet have been introduced with the development of mobile computing technologies. Although many proposed handover schemes utilize multiple interfaces, having multiple interfaces can increase power consumption, device installation space and hardware costs of mobile devices. Therefore, we have been studying handover schemes for mobile nodes with a single wireless network interface. To achieve seamless and efficient handover, we focus on stream control transmission protocol (SCTP) which offers message-oriented, reliable and connection-oriented delivery transport service. Unlike other transport protocols such as TCP, SCTP can provide an end-to-end handover mechanism with a multi-homing feature. However, the handover mechanism in the current SCTP causes large handover delay especially when a mobile node has only one single wireless network interface. In this paper, we have investigated the current issues in the SCTP handover mechanism and propose a new handover scheme based on SCTP, which identifies a communication path as a pair of source and destination address. We also propose new data retransmission feature for smooth handover.

Area-Based Activity Information Preservation mechanism for ubiquitous sensor environment

Recent years have seen active development of context-aware applications and systems that helps the development. However, it suffers from increasing fears for leakages of userspsila activity information to other users unconsciously, since the owner of the activity information included in the sensor data is not treated in context-aware systems. We propose the area-based activity information preservation (ABAIP) system that enables users to control the level of data resolution of their activity information to allow applications to use. Degrading sensor data resolution causes coarse grained context recognition. The system prevents unconscious and unnecessary activity information leakage amongst the ABAIP system users, while providing ubiquitous sensor environment for various kinds of ubiquitous software.

Privacy Respected Ubiquitous Sensor Environment

Recently, research and development of small wireless sensor nodes are active, such as Crossbow Motes and muPart . These are exploited to construct ubiquitous services by attaching on daily objects such as cups or chairs. An example service is a smart coffee maker, which drips coffee when coffee in a sensor attached cup gets cold. The sensor node attached daily object is called Smart Object (SOBJ) and the service is called SOBJ Service. In addition, the environment where SOBJ service works is called SOBJ Environment. We aim to clarify the following three points: 1) who has the access control right, 2) who has the right to see the data, and 3) how to disclose the data.