New Wireless Network for Sensors and Actuators

Selected Papers: Wide Area Ubiquitous Network

Wide Area Ubiquitous Network: New Wireless Network for Sensors and Actuators

Hiroshi Saito†

Abstract This paper introduces the concept of a new wireless network infrastructure called the wide area ubiquitous network (WAUN). In this network, each cell has a wide coverage and can accommodate many low-power-consumption low-capability terminals, which can work as sensors and actuators. Examples of new applications that WAUN should support are shown and the features of WAUN are discussed. This paper also describes the importance of long-range wireless access with low-power transmission as a basic principle for the design targets of WAUN.

1. Introduction anywhere and anytime with anybody and anything and can enjoy a convenient life [3]. The number of A wide area ubiquitous network (WAUN) is a con- such small computers embedded in devices is expect- cept for a new wireless network infrastructure. In this ed to be huge and their size is expected to be tiny. network, each cell has a wide coverage and can Though one device cannot do very much, we expect accommodate many low-power-consumption low- such devices to do a lot if they are networked. capability terminals, which can work as sensors and The feasibility of such concepts strongly depends actuators. Similar concepts, such as computers locat- on recent developments in network technology, and ed anywhere in the TRON project and ubiquitous the implementation of these concepts seems to computing were advocated by Ken Sakamura [1] and require a new network in which devices are used as Mark Weiser [2], respectively, in the 1980s. These terminals. However, it is unclear what this network concepts have now become achievable targets as a should be. result of recent developments in electronics, micro- This paper considers scenarios in which a huge mechanics, and telecommunications (mainly wireless number of devices, far more than the existing number technologies), and there are many projects in which of personal computers and cellular phones, are net- numerous small computers embedded in devices are worked. In such circumstances, most of the terminals distributed to perform some services as feasibility will be low-capability and low-performance ones demonstrations. For example, the Japanese govern- because otherwise the total cost of the terminals ment has formulated a “u-Japan” plan and is launch- would be extremely high. The main aim of this paper ing a “u-Japan” program to achieve the objectives of is to discuss what kind of network NTT, as a network the plan, where “u” means ubiquitous. provider, should offer for such low-end terminals By using ubiquitously networked small computers, [4]. including sensors and actuators, we can be networked 2. Applications † NTT Network Innovation Laboratories Musashino-shi, 180-8585 Japan What are the applications for the scenario that we Email: [email protected] consider here? That is, what applications are possible

NTT Technical Review Selected Papers: Wide Area Ubiquitous Network

Example 1: Medicine usage management by detecting when MEDICINE tablets are removed from a package.

Example 2: Updating a business card that has already been distributed.

Example 3: Name seal management by detecting use of a name seal.

Example 4: Detecting the opening of an envelope or a page of a book/catalog. 0,000 ¥00,00

Example 5: Usage evidence by detecting the opening of a package.

Fig. 1. Examples of new applications.

in an environment where many low-end low-power- In addition to applications such as these that have consumption terminals are deployed. The following already been proposed, we think that much simpler ideas are currently at the stage of recently introduced devices will be networked for new applications and commercial services or commercial trials in Japan. that the number of such devices will be much larger (1) A house with security sensors detects motion than the number of terminals for the initial applica- and counts heart beats in the bathroom to enable tions. Some examples of such new applications are a rapid response to sudden sickness, such as a given below and illustrated in Fig. 1 [5]. heart attack by a person in the bath. (4) Managing medicine usage by detecting when (2) An inventory system with sensors in tanks such tablets are removed from a package. Medicine as car gasoline tanks and beer tanks measures is sometimes not used correctly. In particular, the quantity remaining, and an inventory man- elderly persons forget to take their medicine. As agement system receiving the sensor data deter- a result, medical costs increase and doctors can- mines the schedule for refilling the tanks. not judge whether the medicine is effective. (3) An environment protection and disaster man- (5) Updating a business card after it has been given agement system obtains data from temperature, out. Business cards are distributed in business moisture, and chemical substance sensors scat- meetings but the information can soon become tered in a forest to detect forest fires and envi- out of date. The updatable business card has a ronmental destruction very quickly or to calcu- simple electronic paper display with a wireless late the CO2 processing capacity of the trees or transceiver, and a paper-like thin-film battery obtains data from acceleration and strain sen- enables the information on the business card to sors installed to detect landslides and earth- be updated. quakes to shut down gas supply pipelines, stop (6) Managing personal seals by detecting when a high-speed trains, or set traffic lights to red. seal is used to make an imprint. In many busi-

Vol. 6 No. 3 Mar. 2008 Selected Papers

ness situations as well as many private situa- another aspect of our design target. In many applications, Japanese people use name seals in place tions, terminals will operate on built-in batteries. If of the signatures used in western countries. the number of terminals is very large and the battery Being able to detect and manage the use of life is short, batteries everywhere will need to be name seals in business situations would greatly changed. To avoid such a situation, the battery life help the computerization of office work. should be long. Low-power-consumption is the key (7) Detecting the opening of an envelope or a page to a long battery life. In addition, unlicensed use of of a book/catalog. This would enable a mail wireless devices with transmission power of less than order business to detect that the person is inter- 10 mW is allowed in Japan and many other many ested in the book or the product on the page. countries. Thus, a wireless access range of more than (8) Proving usage by detecting when a package is a few kilometers using a terminal with transmission opened. This would make it easy to count stock power of 10 mW is an important design target of that has and has not been used in an inventory. WAUN. The wireless system and wireless terminal in This could be used as evidence for tax agents WAUN are discussed in other Selected Papers in this and help with inventory management. issue. These new applications are used with commodities In addition to a wide coverage area with low-power- that have never been networked and can be imple- consumption terminals, in order to support the cre- mented by very small simple sensors or actuators that ation of a ubiquitous networked society, WAUN must are networked. Although these terminals are very satisfy at least the following requirements: scalability low-end ones and do not need high transmission regarding the number of terminals, terminal mobility, rates, these applications will result in an extremely support for low-capability terminals, security, econo- large number of terminals. In addition, these termi- my, and provision of environments for easy develop- nals may be treated as expendable, being used once ment of new applications and collaboration with and then discarded. existing services such as Web services. Therefore, our WAUN project is conducting research to satisfy all 3. Wide area ubiquitous network these requirements. Middleware functions, which are expected to resolve some of the problems, are dis- A promising approach for implementing ubiquitous cussed in section 4. connectivity is to organize local networks with multi- The features of WAUN are as follows (Fig. 2). hopping and ad-hoc networking wireless mobile (1) WAUN works as a middle box between a wire- nodes equipped with short-range wireless devices less terminal and a wired terminal. The trans- such as ZigBee, a wireless local area network, or parent communication between them is limited. Bluetooth. However, some applications need connec- For example, the IDs (identification numbers) tivity in public areas or outside the user’s home/office. are converted, and the ID that the wired termi- In such situations, this approach causes technical nal uses to identify the wireless terminal is dif- issues such as the power consumed when a wireless ferent from the one that the wireless terminal mobile node is used as a mobile switching node, the knows as its own ID. security threat to mobile switching nodes, and an (2) The wireless link has a large range (about 5 unstable service area or routing due to too many km). The range will be kept large by using mobile nodes having excessive freedom of move- reception diversity based on maximal ratio ment. combining. This will enable a network provider Thus, we have concluded that WAUN should pro- to cover a wide area with a small number of vide long-range wireless access. If the range is longer access points and thus offer a service at a rea- than a few kilometers, we can make full use of exist- sonable cost. ing assets. This is because existing local network (3) Wireless terminals are not IP (Internet protocol) operators have their own buildings every few kilome- terminals and do not use TCP/IP (transmission ters and those buildings have communications and control protocol, Internet protocol) because it power supply cables on their roofs. Therefore, we can has too much overhead and wireless terminals put antennas on the tops of these buildings without have low-performance CPUs (central process- additional cable costs. ing units) and little memory. The radio access In addition, low-power-consumption or long bat- network gateway servers (RANSs) offered by tery life under long-range wireless communication is the network provider convert the wireless link

NTT Technical Review Selected Papers

Radio IP access Wired Access IP backbone network gateway network terminal point server (IP-GW) (RANS)

Subscriber, authentication, Location and ID Wireless management management Application server terminal server server

Database Database Database

Fig. 2. Wide area ubiquitous network (WAUN).

protocol dedicated to WAUN wireless terminals wireless terminal has sufficient CPU performance into protocols developed in the IP community. and memory, users have the ability to develop appli- RANSs also convert IDs (see (7)). cations, and the wired IP terminal can work as a (4) Wireless terminals can move. The mobility server, so the basic capabilities of WAUN may be suf- management function maintains the area in ficient. However, this will often not be the case. Thus, which a wireless terminal exists. This function WAUN middleware is provided to compensate for is implemented by location registration tech- this situation. The middleware eases the development nologies similar to those used in cellular net- of applications by being introduced in wireless termi- works. nals and wired IP terminals as well as offering users (5) Wired terminals are IP terminals that communi- higher-layer platform services by being introduced in cate with wireless terminals in WAUN and are wireless terminals and application servers within accommodated through the IP gateway (IP- WAUN. GW). Their interface with WAUN is a widely Higher-layer platform services may include (1) used common interface such as TCP/IP, but receiving and accumulating sensory data sent by wired IP terminals are prevented from directly wireless terminals, (2) searching for and finding tar- accessing WAUN network entities such as get sensory data in the accumulated sensory data, (3) RANS for security reasons. WAUN does not distributing the sensory data sent from a wireless ter- support mutual communication between wired minal to a destination registered by the user or IP terminals. according to logic programmed by the user, and (4) (6) Special middleware functions are offered in downloading actuator commands to the wireless ter- WAUN to compensate for the low capabilities minal associated with the actuator through the user of the terminals. Details are given in section 4. program. Such higher-layer services mean that the (7) In WAUN, several IDs are used to make the user need not set up servers to receive data from the service convenient, secure, and efficient. wireless terminals or provide programs that can be WAUN offers security functions and ID conver- accommodated in the wireless terminal, which has sion/resolution. In particular, to prevent track- limited memory and CPU performance. ing by a stranger, the ID is assigned temporarily Higher-layer services may also be useful for anony- and often updated. This ID management with mously, offering sensory data obtained by one user to mutual authentication between the terminal and another user. A mediation service among the higher- the network enables us to achieve secure com- layer services receives sensory data obtained by a munication. user and sends it to another user while hiding the identity of the user who provided the original data. 4. Middleware functions This service is useful for secondary use of sensory data because it can conceal private information. WAUN offers basic capabilities for collecting sensory data and transmitting actuator commands. If the

Vol. 6 No. 3 Mar. 2008 Selected Papers

5. Conclusions Hiroshi Saito Executive Manager, Ubiquitous Service System Laboratory, NTT Network Innovation I introduced the concept of a wide area ubiquitous Laboratories. network (WAUN). To support new applications with He received the B.E. degree in mathemati- cal engineering, the M.E. degree in control simple terminals economically, it has large cells, low- engineering, and the Dr.Eng. degree in teletraf- fic engineering from the University of Tokyo, power-consumption protocols and terminals, and Tokyo, in 1981, 1983, and 1992, respectively. He joined Nippon Telegraph and Telephone middleware. The other Selected Papers in this issue Public Corporation (now NTT) in 1983. He provide additional details about WAUN. received the Young Engineer Award from the Institute of Electronics, Information and Com- munication Engineers (IEICE) of Japan in 1990, the Telecommunication Advancement Institute References Award in 1995, and the Excellent Papers Award from the Operations Research Society of Japan (ORSJ) in 1998. He is a fellow of IEEE, IEICE, [1] K. Sakamura, “Ubiquitous Computer Revolution,” Kadokawa Pub- and ORSJ, and a member of IFIP WG 7.3. lishing, 2002 (in Japanese). [2] http://www.ubiq.com/hypertext/weiser/UbiHome.html [3] http://www.soumu.go.jp/menu_02/ict/u-japan/ (in Japanese). [4] H. Saito, M. Umehira, and M. Morikura, “Considerations of Global Ubiquitous Network Infrastructure,” IEICE Trans., Vol. J88-B, No. 11, pp. 2128–2136, 2005 (in Japanese). [5] H. Saito, M. Umehira, and T. Ito, “Proposal of the wide area ubiquitous network,” World Telecommunication Congress, Budapest, Apr. 2006.

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