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Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 APPLICATION OPPORTUNITIES IN BLUETOOTH NETWORKS Agus Wibowo Jurusan Teknik Informatika, Fakultas Teknologi Komunikasi dan Informatika, Universitas Nasional Jl. Raya Sawo Manila, Pejaten No. 61, Jakarta 12520 Email: [email protected] Abstrak Dalam makalah ini dilakukan analisa teknologi bluetooth dari sudut pandang jaringan yang memliki jangkauan luas dibandingkan dengan jangkauan terbatas. Teknologi bluetooth memiliki kelebihan dalam kesederhanaan infrastruktur jaringan dan menyediakan feature yang aplikatif untuk melakukan tarnsfer data. Kata kunci: Bluetooth, mobile devices, PAN, BNEP, access points, hot spots, mobile commerce, M2M Abstract This paper analyzes the Bluetooth technology in the perspective of networks that reach further than traditional personal area networks. It begins by giving some technical background on the Bluetooth technology together with discussion about motivations behind it. At the same time as the technology is gaining wide acceptance and new devices are introduced into the market there seem to be a shortage of applications that would utilize the full potential of the Bluetooth technology. Examples of these applications are given with some arguments concerning the applicability of the technology in the corresponding framework. Key Words: Bluetooth, mobile devices, PAN, BNEP, access points, hot spots, mobile commerce, M2M I. INTRODUCTION Bluetooth is an industry standard for wireless connectivity of various devices within relatively short range. There are four factors that make the technology appealing especially in field of mobile devices (Buttery and Sago 2003; Kraemer and Schwander 2003): · · · · A compliant implementation requires only a small space and therefore it can be included easily in small devices It consumes so little power that it does not significantly reduce the battery life of the device Compact implementation and mass production enables low-cost solutions It is relatively robust against radio interference As being around for a while the Bluetooth technology is entering a phase in which initial problems with interoperability and classic dilemma of over-marketing can be put aside to take a realistic look over potential benefits Bluetooth can offer in the context of various applications. This paper begins by giving a brief introduction to Bluetooth standard in historical, organizational and finally in technical sense with a bias towards features that allow building of applications to take the technology further from being just a wireless connector of personal gadgets. 85 Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 Following the technical discussion, some examples are given of what these applications could be together with some discussion of how the Bluetooth technology can make the realization of these types of applications more fruitful. II. TECHNOLOGY Ericsson, Nokia, Intel, IBM, and Toshiba formed the Bluetooth Special Industry Group (SIG) in 1998. The main function of the Bluetooth SIG is the development of the industry standard Bluetooth technology and bringing it to market. The name Bluetooth was inspired by Herald Blåtand, the king of Denmark during the years 940 to 981. Blåtand united Norway and Denmark during his reign, as Bluetooth technology was to unite personal computing devices. Initially the name was considered temporary, but as it turned out to be a daunting task to come up with a better name, it became permanent. As of now the Bluetooth SIG has over 3,000 member organizations. The SIG offers all the intellectual property included in the Bluetooth specification and usage of the Bluetooth SIG trademark royalty-free to the member organizations. The development of specification is made available to general public only when it is finished and approved. Member organizations have early access to the draft specifications and possibility to contribute to the development depending of the level of membership in the SIG. Joining as an adopter member is free of charge (Bisdikian 2001; SIG 2004). To be eligible to use the Bluetooth specification as a member of the SIG, the manufacturer needs to qualify all products through the Bluetooth Qualification Program (BQP). Qualification includes tests for physical layer, protocol conformance, profile conformance and profile interoperability. In addition to BQP, the Bluetooth SIG is sponsoring UnPlugFests, which provide a forum for the manufacturers to perform interoperability functional tests (SIG 2002). The Bluetooth specifications are partitioned to the core specification and to numerous profile specifications that can be maintained individually. The current version of the core specification is 1.2. Earlier releases of the Bluetooth specification bundled the core specification and profiles together (SIG 2004). Core specification defines the radio characteristics and communication protocols involved in data exchange between Bluetooth devices. Profiles describe how these protocols can be used to implement applications in multitude of pre-defined categories. Core Specification The Bluetooth protocol stack is depicted in Figure 1. Although it is not part of the Bluetooth specification, the protocols can be divided into two categories: transport and middleware protocols. Transport protocols consist of protocols that have been developed specifically for the Bluetooth technology. Middleware protocols consist of both Bluetooth specific and adopted protocols, which are used selectively to enable different application profiles. Normally the middleware protocols shield the specifics of the Bluetooth technology from the actual applications (or profiles), while naturally the actual data transfer is always taking place through transport layer protocols (Bisdikian 2001). 86 Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 Applications / Profiles PPP ... RFCOMM SDP TCS ... L2CAP Middleware Protocols HCI Link Manager Transport Protocols Baseband Radio Figure 2.1 Bluetooth Protocol Stack (adapted from Bisdikian 2001) The lowest layer in the protocol stack is the radio layer. Bluetooth radio uses the 2.4 GHz unlicensed ISM band. The spectrum is divided from 2402 GHz to 2480 GHz into 79 channels, each 1 MHz wide. A pseudo-random hopping at 1600 Hz is performed, which effectively reduces interference. Currently the symbol rate is 1 Ms/s supporting the bit rate of 1 Mb/s (SIG 2003). Bluetooth devices are classified in three transmit power classes presented in Table 1. Given characteristics of a typical Bluetooth device, most current implementations use power class 2, typical operating range being around 10 meters. The transmit power of devices can be further adjusted in operation to conserve power and avoid interference. The baseband offers the fundamental elements for Bluetooth communication. Each Bluetooth devices has a unique IEEE-type 48-bit address called Bluetooth device address (BD_ADDR) allocated at manufacture time. Communicating devices acquires these addresses together with devices’ free-running 28-bit clock value from each other when they are engaging in communication. Bluetooth connections can be authenticated and connection link further encrypted. Authentication is based on a challenge-response mechanism, which is based on a link key generated from a PIN provided by the user. Possible encryption based on the SAFER+ algorithm is performed using up to 128-bit long encryption key generated from the link key. Encryption and authentication is negotiated in the link manager layer. L2CAP layer on its part provides connectionless or connection oriented interface to the middleware protocols (Bisdikian 2001). Table 2.1 Power classes (SIG 2003) with ranges Pow er Clas s 1 2 3 Maximum Output Power Estimated range 100 mW (20 dBm) 2.5 mW (4 dBm) 1 mW (0 dBm) 100 m 10 m 0.1 – 10 m 87 Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 Amongst the transport layer protocols is the Service Discovery Protocol (SDP), which is used to discover services provided by Bluetooth devices in the network. RFCOMM is used to emulate serial connections, while Telephony Control Specification (TCS) provides call control in Q.931 fashion (Vaxevanakis et al. 2003). IP services can be offered using PPP protocol running on top of RFCOMM protocol as it is proposed by the Bluetooth LAN access profile. However, this is neither efficient nor optimal solution. In addition to the overhead involved, PPP is not sufficient for ad-hoc networks containing multiple hops. Therefore PAN (Personal Area Networking) profile is being developed to provide Ethernet-like interface called Bluetooth Network Encapsulation Protocol (BNEP) for IP services (Chan et al. 2003). Networking Two or more Bluetooth devices that share a same channel (hop sequence) form a piconet. A device participating in a piconet acts either as a master or a slave. Every piconet has one master and up to seven active slaves. There is no direct transmission between slaves; data must be always relayed through the master device instead. Two or more piconets can be interconnected forming a structure called a scatternet, as depicted in Figure 2. Piconets are linked together by a device that is member of both piconets. A device can be acting simultaneously as a slave in many piconets, but it can be a master of at most one piconet. Participation in multiple piconets is performed on a time-division multiplex basis, as a device can transmit and receive data only in one piconet at a time (Johansson et al. 2001). Currently the Bluetooth specification defines mechanisms that allow the existence of the scatternet so that participating piconets remains functional as themselves. It does not define how the information is to be routed through devices interconnecting the piconets in the scatternet. It is therefore difficult to deploy larger-scale IP services using pure Bluetooth network and interoperability of such solutions cannot be guaranteed. As was presented in last subsection, PAN profile is utilizing the BNEP protocol to provide a broadcast segment for IP service. PAN working group is working on providing a broadcast segment that would cover the whole scatternet instead of only one piconet. The research work around Bluetooth is particularly active in the field of scatternet forming, intra- and inter-piconet scheduling and routing. S S/M S M S S/M S S S S S M S S: Slave M: Master Figure 2.2 A scatternet with four piconets. III. APPLICATIONS After initial difficulties, the Bluetooth technology has found its way to a large number of different kinds of mobile equipment. Silicon chip vendors have been able to produce single chip 88 Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 Bluetooth solutions and demand is bringing mass production prices of these solutions down towards the magic $5 barrier. These enabler solutions are used to build products that live up to the original Bluetooth spirit of strict power, size and price constraints. These products satisfy easily the initial objective of the Bluetooth technology: acting as a cable replacement technology for a user wanting to link various mobile and stationary devices like wireless keyboards, PDAs, digital cameras and mobile phones in an ad-hoc manner. However, by taking the Bluetooth technology further in the field of networking could be beneficial to a broad range of users and it would bring in some new players to the picture as well. This development is clearly seen in active research, standardization and in product portfolios of Bluetooth manufacturers. It is interesting to note that as this development is taking Bluetooth closer to the field of WiFi (IEEE 802.11), there is ongoing development in opposite direction to equip PDAs and mobile phones with WiFi connectivity. Besides this, there is little or no point in considering WiFi and Bluetooth being competing technologies, since the development of these technologies is driven by different requirements and motivations. The rest of this section will present some applications for Bluetooth networks. Traditional PAN and cable replacement scenarios are well covered in numerous publications and won’t be discussed further in this document. Presented applications do not form an exhaustive overview of what can or cannot be done with Bluetooth technology; they are plainly selected as an example to elaborate on it. Single-cell and multi-cell mobility solutions for home and office Numerous manufacturers are developing Bluetooth access points, which can be used to provide “stationary” Bluetooth networks for homes and offices. These access points can offer TCP/IP services running on top of traditional Ethernet, WiFi or GSM/GPRS. As access points are usually mains-powered they are likely to operate in high power mode (class 1) and run its radio receiver in a mode that requires more power but improves its sensitivity (Buttery and Sago 2003). This can offer a range of approximately 100 meters in optimal conditions, which is substantially more, than what have been used to with traditional battery operated Bluetooth devices. To enhance coverage of Bluetooth network even further, an installation of multiple access points can be used to provide a multi-cell access solution. However, this approach is susceptible to challenges related to inter-piconet communication inside a scatternet (see subsection 2.3) and handovers, which are currently not covered by the Bluetooth specification. Bluetooth access points in home or office environment can be used to provide many interesting services. Finnish company Bluegiga Technologies is offering VoIP, application installation systems, E-mail and calendar solutions on top of their access point products. These services can be conveniently accessed via Bluetooth enabled mobile phones or PDAs (Bluegiga 2004). Public access hot spots Many companies around the world are providing public access wireless network services in a form of hot spots. From the technical point of view the solution is not quite different from mobility solutions for home and office presented in the previous subsection. However, business aspects related to this application are completely different. While the attractions of hot spots are quite obvious, they can be quite difficult turn into a commercial success. Before hot spots can be of any of commercial success, at least the following conditions must be met (Buttery and Sago 2003): · Someone has to need the service enough to pay for it · They have to have suitable equipment to access the service · They must have opportunity (time, space and security) to actually use the service · Before being able to use the service, they must be in the area of coverage 89 Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 Bluetooth has potential to facilitate the situations as it extends the public wireless access concept into the consumer market space. This greatly increases the potential user base for these hot spots by enabling novel mass-market applications. One might argue that an average Bluetooth device is more conveniently accessible it the vicinity of a hot spot, than an average WiFi device for example. Furthermore, different usage patterns would emerge in the form of wide variety of different kinds of consumer market products like smart phones and MP3 players (Buttery and Sago 2003). “mCommerce” Incorporation of Bluetooth technology in mobile phones establishes some interesting possibilities for mobile commerce. Electronic wallet architectures benefit greatly from the fact that these devices can simultaneously access both cellular GSM/GPRS network and short-range Bluetooth networks. As security aspects of such solutions are of great concern they can further take advantage of the security offered by the Bluetooth technology itself, which is considered to be rather good. Mjølsnes and Rong propose a solution for online e-wallet system with decentralized credential keepers. It requires that mobile device used in performing the transaction has both short range communication capability and access to cellular packet switching network. As an example, when a customer is paying the bill in the restaurant, his mobile phone uses Bluetooth to connect to the point-of-sales provided for on the premises and simultaneously access the credential keeper using services of the GPRS network (Mjølsnes and Rong 2003). M2M M2M (machine-to-machine) is a marketing term surrounding an emerging set of technologies to support wired or wireless communication between machines. To take the definition further it also stands for man-to-machine (or vice versa) and mobile-to-machine communication. As the number of embedded processors in the world is growing at a staggering rate, there is an increasing need to enable data exchange between various systems and eventually with their users. There are lots of potential uses of short-range wireless technology like Bluetooth in M2M systems. For example in the field of telemetry, there exists potentially a need to gather information from a large number of sensors located relatively close to each other. This information needs to be gathered efficiently and then sent forward for further analysis. To save infrastructure costs and facilitate installation and relocation, it is easy to prefer wireless sensors over wired ones. However, usually the sensors have to be small, cheap and require as little power as possible. For these and many other reasons it is not applicable to equip sensors with technology to access cellular networks directly be themselves. One possible solution is to use Bluetooth technology in sensors when operating in suitable distances. A compact Bluetooth implementation can be incorporated in many different types of sensors with a modest cost. Consolidated information from sensors can be collected to a database, from were data can be either queried for or transferred forward to other systems using conventional cellular network services. IV. CONCLUSION Despite its slow and over-promoted start, it is fair to say that future of Bluetooth looks bright. The penetration of Bluetooth enabled mobile phones, PDAs and other consumer products is growing steadily and there seem to be no alternative technologies widely available to address the need for affordable low-power wireless networking for myriad of mobile devices. It will remain to be seen, if emerging technologies like UWB, and the potentially increased capacity offered with 90 Jurnal Artificial, ICT Research Center UNAS Vol.2 No.2 Juli 2008 ISSN 1978-9491 them will be able to challenge this. Meanwhile, as it seems that Bluetooth hardware is being created faster than software (Erasala and Yen 2002), there is a definite need for new services and applications that take the technology further from the realm of personal cable replacement. From the technical point of view, there are no major obstacles for this development, although some issues remain to be solved especially related to formation and operation of Bluetooth scatternets. REFERENCES [1] Bisdikian, C. 2001. An Overview of Bluetooth Wireless Technology, IEEE Communications Magazine, December 2001, pp. 86-94. [2] Vaxevanakis, K.; Zahariadis, Th.; Vogiatzis N. 2003. Wireless home networks: A review on wireless home network technologies, ACM SIGMOBILE Mobile Computing and Communications Review, Volume 7 Issue 2, October 2003, pp. 59-68. [3] SIG 2002. Bluetooth Qualification Program Reference Document (PRD), version 1.0, February 2002, http://qualweb.bluetooth.org/Content2/DownloadExecute.cfm?RevisionHistoryID=418&Fil eName=PRD1-0.pdf. [4] SIG 2003. Specification of the Bluetooth System, version 1.2, Volume 2, Core System Package, November 2003, https://www.bluetooth.org/foundry/adopters/document/Bluetooth_Core_Specification_v1.2. [5] SIG 2004. The Official Bluetooth Membership Site. http://www.bluetooth.org. [6] Chan WC. et al. 2003. Quality-of-Service in IP Services over Bluetooth Ad-Hoc Networks, Mobile Networks and Applications, December 2003, Volume 8, Issue 6, pp. 699-709. [7] Johansson, P. et al. 2001. Bluetooth: An Enabler for Personal Area Networking, IEEE Network, Volume 15, September 2001, pp. 28–37. [8] Buttery, S.; Sago, A. 2003. Future applications of Bluetooth, BT Technology Journal, Volume 21, Issue 3, pp. 48–55. [9] Erasala, N.; Yen, D. 2002. Bluetooth technology: a strategic analysis of its role in global 3G wireless communication era, Computer Standards & Interfaces, Volume 24, Issue 3, July 2002, pp. 193-206 [10] BlueGiga 2004. BlueGiga Technologies web site. http://www.bluegiga.com. [11] Mjølsnes, S.; Rong C. 2003. On-Line E-Wallet System with Decentralized Credential Keepers. Mobile Networks and Applications, Volume 8, Issue 1, February 2003, pp. 87-99. [12] Kraemer, R.; Schwander, P. 2003. Bluetooth based wireless Internet applications for indoor hot spots: experience of a successful experiment during CeBIT 2001, Computer Networks, Volume 41, Number 1, January 2003, pp. 303-312. 91