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7.0 The Architecture of Bluetooth Protocol
The complete protocol stack for Bluetooth can be clearly seen above. Those shaded blue, are protocols designed specifically for the Bluetooth technology.
Baseband: The Baseband and Link control layer enable the physical RF connection between any Bluetooth enabled products wishing to form a piconet. This layer also controls the synchronisation and the frequency hopping sequence.The 2 different link types Synchronous Connection Oriented (SCO) and Asynchronous Connectionless (ACL) are also managed by this layer.
Audio: Audio transmissions can be performed between one or more Bluetooth enabled units, using a number of different usage models. Audio data does not go through the L2CAP layer (see diagram 1) but directly between 2 Bluetooth units.
Host Controller Interface (HCI): The Host Controller Interface provides an interface method for accessing the Bluetooth hardware capabilities. It contains a command interface, which acts between the Baseband controller and link manager and has access to hardware status. It contains the control and event registers.
Link Manager protocol (LMP): The Link Manager Protocol, is responsible for link set-up between Bluetooth enabled units. It handles the control and negotiation of packet sizes used when transmitting data. The Link Manager Protocol also handles management of power modes, power consumption, and state of a Bluetooth unit in a piconet. Finally, this layer handles generation, exchange and control of link and encryption keys for authentication and encryption.
Logical Link Control and Adaption Protocol (L2CAP): The Bluetooth logical link control and adaptation protocol is situated over the Baseband layer and beside the Link Manager Protocol in the Bluetooth protocol stack. The L2CAP layer provides connection-oriented and connectionless data services to upper layers.
The four main tasks for L2CAP are:
Service Discovery Protocol (SDP): The Service Disocvery Protocol defines how a client's Bluetooth enabled application will discover available Bluetooth server' services and characteristics upon entering a Bluetooth server area. SDP also provides functionality for detecting when a service is no longer available.
RFCOMM: RFCOMM protocol is a serial port protocol. The protocol covers applications that make use of serial ports of the unit. RFCOMM emulates RS-232 control and data signals over the baseband. It also provides capabilities for the upper service levels such as OBEX, which uses a serial line as a transport mechanism.
Descriptions of the remaining protocols including OBEX, WAP and TCP can be found in the Glossary. More information on these protocols can be found at www.palowireless.com/infotooth/tutorial.asp
(See Reference 2 for more details) 8.0 Security Issues and Encryption (See Reference 2 for more details) The general security architecture can be seen clearly on the left. The key component is a security manager, which has some of the following tasks:
Store security-related information on services and devices
Answer access request by protocol implementations or applications
Enforce authentication and/or encryption before connecting to the application
Initiate pairing and query PIN entry by the user. PIN entry may be done by application
8.1 Connection/Set-up Procedure
The Diagram (on the left) shows the information flow to a trusted service:
1) A connection is requested to
L2CAP2) L2CAP requests access from the security manager
3) The security manager searches the service database for a stored link key
4) The security manager searches the device database for a stored link key
5) If necessary, the security manager enforces authentication and encryption
6) The security manager grants access
7) L2CAP continues to set-up the connection
8.2 Authorisation and Authentication
Authentication
is the process of verifying 'who' is at the other end of the link. Authentication is performed for devices; this is achieved through the procedure of authentication being based on a stored link key or by pairing (entering a PIN).Authorisation
is the process of deciding if a given device is allowed access to a given service. Trusted devices (authenticated) are allowed access to services. Untrusted or unknown devices require authorisation before access is granted. (Authorisation may be given automatically by an application.) Authorisation always includes authentication.For a 'trusted' device, a link key is stored after being authenticated and the device is marked 'trusted in the Device Database. For an 'untrusted' device, even if it has previously been authenticated, the link key is stored but the device is not marked as 'trusted' in the Device Database. For an 'unknown' device, no security information is available for the device. (An 'unknown' device is an 'untrusted' device!)
8.3 Encryption and Key Size Negotiation
The master and the slave must first decide whether encryption is necessary and whether encryption should apply to both point-to-point packets and/or broadcast packets. If the master and the slave agree on encryption, the master will continue to give more encryption information.
The encryption key size varies from 8 to 128 bits - the 2 devices wishing to make a connection must agree the size of the encryption key to use. In each device, a parameter defines the maximum size of the key length. In the key size negotiation, the master unit sends its suggested encryption key size to the slave. The slave can either accept and acknowledge, or send an alternative key size.
In every application, there is defined a minimum acceptable key size, and if the requirement is not met by either of the participants, the application aborts the negotiation and encryption cannot be used. This is necessary to avoid the situation where malicious devices force encryption key sizes to be low in order to cause impairment.
The encryption algorithm uses four ‘Linear Feedback Shift Registers’ of with the lengths totalling 128. The initial 128-bit value of the four LFSRs is taken from the key stream generator using the encryption key, a 128-bit random number, the Bluetooth device address and the 26-bit value of the master clock.
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9.0 Health Implications with Bluetooth
"Bluetooth wireless technology makes it possible to use short-range wireless connections between mobile phones, laptops, printers, headsets, cameras and many other devices at home or at work. With Bluetooth wireless technology, cables are replaced by radio communications.
Bluetooth products contain small radio transmitters and receivers. The normal output power is very low, only 1 mW (1/1000 of a watt), which gives a working range of about 10 meters. The maximum exposure levels from Bluetooth products are well below the prescribed safety limits. Normal Bluetooth devices (1 mW) reach one hundredth of the safety levels at the most.
The risk of Bluetooth devices causing electromagnetic interference in sensitive electronic equipment, for example medical devices, is minimal because of the very low output power."
It can be seen therefore, that the power level output is minute. If you compare the output of a Bluetooth enabled product (1mW), to say a mobile phone (700mw), you can see for yourself that the implications and hazards to health really are small in comparison.
(See Reference 3 for more details)
9.1 Monitoring Heart Patients...
Amidst the health concerns of Bluetooth enabled devices, there comes a positive use for the technology, which you may never have considered. MicroMedical Industries chief technology officer 'Bruce Satchwell' has devised the idea of using Bluetooth technology to monitor cardiac patients through their mobile phones! "Satchwell" went on to say that it would obviously be cheaper to have someone at home than in a hospital.
The system works through a 3-way system. A central monitor will be located at the hospital, which will be used in combination with a intermediary device and a heart monitor. The only thing that seems to be impeding progress of the system at the moment is the fact that handsets are not yet widely available at low-cost.
(See Reference 4 for more details)
Issues have recently been raised over the plausibility of Bluetooth enabled products functioning in the close vicinity of a Wireless LAN using
802.11b. Fears over clashes between the two systems have been highlighted, however, developers ultimately concluded that conflicts were within acceptable limits.Tests carried out for ‘Avis’, under the guidance of Barry Issberner (vice president at ‘Symbol’) found that contention was not a major issue, however, Bluetooth enabled products did degrade the performance of the Wireless LAN using 802.11b. The tests involved two notebook computers with Bluetooth cards transmitting files constantly via FTP. A handheld computer with a 802.11b card which was regularly pinging, was turned on 40 feet away. When the handheld computer came within 1 to 3 feet of the Bluetooth enabled notebook computers, the Wireless network slowed from 11 Mbps to 1Mbps.
Despite the slowdown, data was transmitted all of the time and despite issues with Bluetooth, it kept going. At 3 feet, connections experienced some degradation but much less severely. Beyond 6 feet, networks did not suffer from interference. The experiment finally concluded that the two links can run acceptably in the same area.
(See Reference 5 for more details)
10.1 Compatibility Problems
As Bluetooth has started to become a reality, practical issues related to the compatibility of products using slightly different Bluetooth specifications have been raising concern. The initial standard was developed before any products existed and as developers began putting Bluetooth into devices, they invariably found bugs. As a result, a number of revisions of the Bluetooth standard have been made including major changes to the standard.
In the rush however, to get Bluetooth products out on the market place, companies have been using the 1.0b standard and as a result, their products are not compatible with the 1.1 standard released just two months later. In one of the first publicly open displays of Bluetooth, demonstrators using different standards of Bluetooth experienced compatibility problems and ultimately the exhibition was a failure.
11.0 The Market for Bluetooth Products
According to a report published by Cahners In-stat Group (www.instat.com), despite negative reports and economic slowdown, the Bluetooth market will augment rapidly.
The research firm suggests that the growth in Bluetooth enabled devices will provide substantial opportunities for the tecnology with demand for the product shooting up to 955 million by 2005 - a 360% 5-year annual growth rate. (See the graph on the right). The market for Bluetooth radio and baseband silicon will also rise to 4.4 billion US dollars in 2005, with an average selling price of below $10 per unit (around £6).
The most exciting part of the Bluetooth market will be the growth in vertical markets such as point-of-sale, data collection, transportation and healthcare. Combined, these will have a growth of 220% by 2005. Hot spot projects have started to spring up already in areas such as hotels, shopping malls, golf courses, airports and more are expected to arise by the end of the year.
Joyce Putscher, Director of In-stats the consumer and converging market reports; "2000 was a year of trials and tribulations for Bluetooth. However, positive signs are here as more silicon is going into production, more products are closing in on production schedules and are coming to market very soon".
(See Reference 6 for more details)
11.1 Growing Demand for Bluetooth
By the end of this year, TDK predicts that more than 24 million Bluetooth-enabled mobile phones will be in use worldwide. That's a 1780% increase on shipments in 2001. The forecast says that 11 million Bluetooth chipsets have already been shipped. Chipsets are used in mobile phone handsets, printers, headsets, keyboards, pens, cameras, laptops, PCs and PDAs.
"As Bluetooth becomes recognized from its handset penetration, the range of business and consumer applications involving laptops, PDAs and PCs will also rise," said Nick Hunn, managing director at TDK Systems. Hunn predicts that by 2006 Bluetooth chip manufacturers will sell as many products in one week as 802.11b Wireless LAN (Wi-Fi) specialists ship in one year.
The paper says that the war between Bluetooth and Wi-Fi a null as both technologies are suited for their individual tasks. Wi-Fi will be used for wireless network access and Bluetooth will continue to serve as a cable replacement and personal area networking solution.
(See Reference 7 for more details)
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11.2 Recent News
It was reported that a global panel that sets electronics standards approved its own version of Bluetooth technology for short-range wireless networks, paving the way for wider acceptance of the standard that links cell phones, computers and other devices. The Institute of Electrical and Electronic Engineers, an international body that sets the standards for a range of electrical and electronic systems, said its 802.15.1 standard for wireless personal area networks is fully compatible with the Bluetooth 1.1 standard promoted by an industry group.
While Bluetooth has been slow to develop in comparison to other personal-use wireless standards, it has recently begun to catch on, with a number of cell phone makers beginning to build it for their phones and personal digital assistant makers releasing add-on Bluetooth adapters for their devices. The 802.15.1 standard was developed by a subcommittee of the IEEE's broader 802 Standards Committee, which is working on a number of specifications for wireless networks, including the much more commonly known 802.11 wireless network system used for high-speed access in homes and offices.
But both standards operate in the same frequency range of 2.4 GHz, and the Bluetooth SIG has pushed the two standards as complementary for everyday business and personal use. Within the last week, major consumer-electronics companies like Apple Computer, printer maker Epson and PDA maker Palm have released Bluetooth device adapters for their products.
(See Reference 8 for more details)
11.3 Palm releases Bluetooth SDK
Palm's operating system division has launched a test version of a software development kit for Bluetooth, allowing developers to make a start on building applications that work with the wireless networking standard, the company said Monday. Only last week, Palm's device-making division said it has chosen Bluetooth wireless chips from Broadcom for use in future Palm models.
Palm hasn't yet revealed when the first devices using the Bluetooth chip will hit the market, but the company now has both hardware and software kits available for developers to use, said Michael Mace, Palm's chief competitive officer. Bluetooth technology would let Palm users connect wirelessly to other Bluetooth-enabled devices, including cell phones, printers and other Palm computers, Mace said. Connecting to a cell phone would allow users to send and receive e-mail wirelessly using the phone as a modem. The SDK beta, which is available free to registered Palm developers, includes Bluetooth configuration tools, documentation, sample code and Palm's Bluetooth API, Mace said.
Palm also announced worldwide availability of its secure digital I/O hardware development kit, which includes two Palm SDIO Bluetooth cards, a serial cradle and the beta software development kit. The SDIO kit is available from Palm for $199.
For more information visit Palm's Website at http://www.palm.com/wireless/bluetooth/.
(See Reference 16 for more details)
11.4 Epson to Demonstrate Bluetooth Printing Capability
Epson will demonstrate full printing capability using Bluetooth wireless communication technology using the new EPSON Stylus Color 777 color printer with the EPSON Bluetooth Printer Adapter at the beginning of November.
The demonstration will include printing of all Windows text and graphics applications at the full Bluetooth speed of 721 kilobits per second. It will also include a demonstration of printer discovery through the Bluetooth Neighborhood, which shows on screen the Bluetooth-enabled devices that are within range.
Epson officials said Bluetooth printing promises to be a business application that will enhance convenience in both the office and the home with advantages over infrared connectivity.
(See Reference 9 for more details)
11.5 Ericsson's T39m
The T39m is peace of mind in a small and powerful triple band mobile phone. It has GPRS (General Packet Radio Services) giving you instant Mobile Internet access and Bluetooth wireless technology for cablefree comfort.
For more information go to Ericsson's website at www.Ericsson.com 12.0 Bluetooth Developer Kits
Making it easier to develop Bluetooth application.
The rapidly growing wireless industry offers a tremendous opportunity to a wide range of application developers. Bluetooth is opening up a raft of new applications, made possible by wireless technology and existing applications are being extended to wireless environments to increase their effectiveness.
Red-M is now offering a range of Bluetooth developer kits designed to make developing Bluetooth applications as easy as possible.
For more information, please visit:
http://www.red-m.com/Products/bladeDevKit/default.asp
Other sources for developer kits:
http://www.widcomm.com/Products/software_devel_kit_blueconnect.asp
http://www.stonestreetone.com/bluetooth/products/bdk/index.php
http://www.impulsesoft.com/HomePage/products/products_connectfree_dev_kit.html
Bluetooth card's available at Palm.Com
12.1 Bluetooth Instant Messaging and Bluetooth application-development tools
Instant messaging is beginning to fulfil its promise in the Bluetooth market, with the help of Rococo Software. The Bluetooth application-development tool provider is rolling out an Early Adopter Program for its Impronto Developer Kit. Not only is the Impronto DK a Bluetooth developer kit, it is the first standards-based Java tool for developing Bluetooth applications, according to the company.
Rococo demonstrated the Palm OS edition of the Impronto DK at this week's JavaOne. It showed a Palm-based Instant Messaging program written with Impronto DK that enabled real-time instant messaging with a Bluetooth-enabled Palm. Other companies marketing or envisioning various kinds of Bluetooth-enabled IM services include Pretec Electronics and Pico Communications. Also, wireless phone concerns like Ericsson, Motorola and Philips are also introducing Bluetooth-enabled phones.
Rococo's Impronto Developer Kit is available for both Palm OS and Linux, and both implement standard Java APIs for Bluetooth Wireless Technology. A wireless application written with Impronto Developer Kit will run on any standard Bluetooth Java platform without making changes to the code.
See http://www.rococosoft.com/products/purchase.html for more purchasing details.
(See Reference 14 for more details)
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13.1 Infra-red
In the present market, there is no single competitor to cover the entire concept of Bluetooth. Similar technologies exist - the main being
Infrared (IrDA). IrDA operates at a speed of 2400kbps - 4Mbps (greater than Bluetooth), however it has none of the more beneficial advantages as Bluetooth. IrDA requires line of sight, is limited to point to point connections of 1 - 2 metres and it just doesn't have the same amount of practical uses as Bluetooth. In the past IrDA has suffered from problems with compatibility, as there was no standard. This is a valuable lesson that the members of the Bluetooth SIG group have learnt from.
13.2 Ultra Wideband Radio
A new technology called
Ultra-wideband Radio (UWB) is currently under development. Ultra-wideband uses a broad spread of the radio spectrum, with millions of pulses of low-powered emissions per second. The aviation community has expressed concern however, that ultra-wideband could interfere with signals from the Global Positioning Satellite (GPS). In tests with 13 federal navigation and communications systems, including key aviation systems, the NTIA found interference problems that may require reductions in the power of ultra-wideband emissions or protection of antennae. Based on tests, a spokesperson concluded, "there is a potential to operate ultra-wideband devices in the three-gigahertz to six-gigahertz range". Despite the fact that the technique is not yet fully developed, there are fears that UWB may be a threat to Bluetooth because of it's superiority in capacity and power consumption. UWB prototypes indicate payloads of up to 1.25 Mbit/s with 70 metres range at just 0.5 mW power consumption!(See Reference 10 for more details)
UWB, or digital pulse wireless, differs from standard radio signals by using a large portion of the spectrum instead of staying within a narrow boundary. The signals are short-range (230 feet), carry huge amounts of data at high speed (more than 100 Mbps) and use little power without any interference. The ability of UWB to pass through objects with exact timing of single pulses to under a trillionth of a second, opens up vast commercial possibilities.
Because of its short range, UWB is seen as the next generation Bluetooth. Capable of speeds between 400 and 500 Mbps, UWB could run circles around Bluetooth for short-range applications. ‘Xtreme Spectrum’ sees UWB used to wirelessly stream video from your camcorder to your TV or PC. DVD players could stream videos throughout your home. Digital cameras would use UWB to stream photos to your computer without any physical connection. ‘Xtreme Spectrum’ says it will unveil new products within months.
(See Reference 11 for more details)
13.2.1 More Ultra Wideband Radio News
Newly approved ultra wide band (UWB) wireless technology will not have an impact on demand for the long awaited Bluetooth wireless services, according to analysts. The Federal Communications Commission (FCC) last week approved trials of the technology which can deliver wireless connections as fast as 100Mbps.
"Since the FCC decision there have been reports of UWB as the killer of Bluetooth and that's clearly erroneous. UWB does not even target the same market," said Joyce Putscher, director of converging markets and technologies at analyst Cahners In-Stat. High transmission speeds are not required for the bulk of planned Bluetooth connections, she added. "For many applications, especially those that Bluetooth targets, even 10Mbps is an overkill," said Putscher.
Bluetooth is designed to create small personal area networks, while UWB technologies are expected to enable larger local area networks that are more likely to compete with the emerging 802.11 wireless standard than with Bluetooth. UWB also lags behind Bluetooth both in technology and market development. It currently lacks an industry standard, although companies such as JVC, Sony, Panasonic, Intel, Motorola and Sharp are working on devising one, but this could take until 2004.
(See Reference 12 for more details)
13.3 Wireless Local Area Network
The Wireless Local Area Network (LAN) provides an alternative to the traditional LANs based on twisted pair, coaxial cable, and optical fiber. Wireless LANs use one of three transmission techniques: spread spectrum, narrowband microwave, and infrared. The most widely used transmission technique for wireless LANs is the spread spectrum. The signal is spread over a range of frequencies consisting of the industrial, scientific, and medical (ISM) bands of the electromagnetic spectrum. The ISM bands include the frequency ranges at 902 MHz to 928 MHZ and at 2.4 GHz to 2.484 GHz. The maximum data rate is around 11 Mbps with fall back rates of 5.5, 2 and 1 Mbps, depending on distance, noise and other factors. Range can be up to 100m, but this is also dependent on the environment. Compared to Bluetooth technology, the costs are much greater to install a wireless LAN. The wireless LAN will consume a much greater amount of power than that of the Bluetooth technology and also, the hardware requires a lot more space. (More Information on WiFi)
13.3.1 Bluetooth vs. Wireless LAN - Interference
As discussed previously, Bluetooth and 802.11 do cause interference with each other, increasingly as they approach each other, however, both technologies are designed to handle interference. Bluetooth causes more interference with 802.11 than the other way around because of Bluetooth's faster hop rate (600 times faster). While an 802.11 device is transmitting at a particular frequency, A Bluetooth device might hop to this frequency several times before 802.11 hops to the next frequency. Although both technologies drop packets, 802.11 packets are larger and so more information must be re-transmitted.
13.3.2 Bluetooth vs. Wireless LAN - two very different roles
Companies have begun to realise that 802.11 and Bluetooth are designed for two very different roles. Bluetooth is designed for quick, short-range networks and features better power consumption, small protocol stack, robust data and voice transfer, all at a cheap price. These features make it perfect for a WPAN (Wireless Personal Area Network) but limited in terms of WLAN (Wide Local Area Network). Similarly 802.11b is designed for infrequent mobility, IP-based transmission, medium and high data rate.
This makes 802.11b a poor choice for WPAN but an ideal choice for WLAN. The IEEE and Bluetooth Special Interest Group (SIG) have always tried to illustrate this distinction and the fact that Bluetooth is not in competition with 802.11b, but over-ambitious engineers have often overlooked these points. The industry has realised that Bluetooth and 802.11 have a role to play; Microsoft recently stated that the next release of Windows XP will support Bluetooth together with 802.11, which is already supported.
13.3.3 Bluetooth vs. Wireless LAN - Co-existing
To allow co-existence between Bluetooth and 802.11 enabled devices, each device must never use the same frequency at the same time. For 802.11, it is proposed that a dynamic channel selection be used to ensure that the given channel interferes as little as possible with the Bluetooth piconets. Alternatively, 802.11 packets can be fragmented to ensure that any interference is minimised. This however reduced throughput because of the increase in size of the packet headers. Transmit power can also be controlled to ensure that it is no higher than it has to, reducing the overall interference.
(See Reference 13 for more details)
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14.0 Other Sources of Information
For more sources of Information concerning Bluetooth, please visit some of the following links:
http://www.palowireless.com/bluetooth/newsarchive2000.asp
http://www.Bluetooth.com [Download Core and Profile.PDF]
Alternatively Download (zipped) versions of Core.Pdf and Profile.Pdf here
http://www.Ericsson.com/Bluetooth
http://www.palm.com/wireless/bluetooth/
Motorola's Bluetooth Information and Products
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Based on Information taken from this Link (12/02/02) |
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Based on an outlining report of Bluetooth downloadable at http://www.Bluetooth.com (31/03/00) |
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More Information can be found at http://www.ericsson.com/health/statements.shtml (30/11/01) |
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http://news.zdnet.co.uk/story/0,,s2083922,00.html (24/01/02) |
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http://www.latimes.com/technology/la-000000776jan04.story?coll=la%2Dheadlines%2Dtechnology (31/01/02) |
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Based on a report found at http://www.instat.com (30/11/01) |
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Based on news taken from this Link (28/10/01) |
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Based on the following article: http://news.com.com/2100-1040-866051.html (17/10/01) |
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See the following link for more information: http://www.businesswire.com/webbox/bw.110800/203130369.htm (28/10/01) |
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Based on news taken from http://www.palowireless.com/uwb/news.asp (30/11/01) |
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Based on news taken from http://www.mcommercetimes.com/Technology/222 (12/02/02) |
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Based on news taken from http://www.vnunet.com/News/1129377 (12/02/02) |
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Based on news taken from http://www.palowireless.com (12/02/02) |
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Story taken from this link (02/03/02) |
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Follow this link (12/03/02) |
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Story taken from http://www.vnunet.com/News/1129377 (12/02/02) |
