Download application opportunities in bluetooth networks - unas

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.
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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).
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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
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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
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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
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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
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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.
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