First off, let’s quickly discuss what BT is. It’s a short-range wireless protocol operating within the ISM band at 2.4 GHz. It offers communication speeds up to 1 Mbps with an effective range of 30 feet. While these specifications might not seems impressive when compared to other wireless protocols we are familiar with (802.11b), it serves a different purpose.
BT was designed to be a robust protocol that is not complex to the user. Afterall, for the goal of BT to be realized, the connection of different devices should be seamless to the user. It was designed to consume very little power due to it’s intended applications in embedded systems that often run off of batteries (i.e. cell phone, PDA, keyboard, etc...). For this same reason, it needed to be low cost; BT chips, when in typical production, can be embedded into current devices for as little as $5 per chip. The lower the cost, the greater possibility of putting BT in everything from your computer to your coffee maker. BT was originally designed by Ericsson with cell phone implications, so both data and voice capabilities are provided.
Before I dive into technical details, I feel that it’s important to touch on the historical perspective of BT. Where it’s been and where it’s going. In 1997, one of the Bluetooth inventors from Ericsson met with his Intel contact at a bar in Canada. They started talking about Scandinavia and the Vikings and the Ericsson inventor gave his Intel contact a book on the subject called &quot;Röde Orm&quot;. When he had read it, he called the Ericsson Inventor. What about &quot;Bluetooth?&quot; Harald Bluetooth was the Viking king that joined two Scandinavian kingdoms peacefully. The name originally came from, it named after a Danish Viking and King, Harald Blåtand (translated as Bluetooth in English), who lived in the latter part of the 10th century. Harald Blåtand united and controlled Denmark and Norway (hence the inspiration on the name: uniting devices through Bluetooth). He got his name from his very dark hair which was unusual for Vikings, Blåtand means dark complexion. However a more popular, (but less likely reason), was that Old Harald had a inclination towards eating Blueberries, so much so his teeth became stained with the colour, leaving Harald with a rather unique set of molars. And you thought your teeth were bad...
The BT SIG was formed in 1998 to oversee the adoption of BT in industry. Its founding members include Ericsson, IBM, Intel, Nokia and Toshiba The 1.0 version of BT released in 1999; contained many technical issues that needed to be ironed out On top of this, BT was being hyped far more than was warranted during the creation of the Internet “bubble.” While the hype helped ensure the production of BT chips, it put a bitter taste in developers mouths which BT didn’t deliver. However, ...
The adoption of BT was slow to come due to the absence of some big names. That issue was resolved in late 1999, when 3Com, Lucent, Microsoft, and Motorola joined the BT SIG to form the Promoters Group. In mid-2001, a new version of the BT specifications was released. Version 1.1 fixed device installation issues, connectivity, and interoperability problems that plagued the 1.0 specification Microsoft, following on the heals of Apple, finally released BT support for Windows XP in late 2002. Let’s face it, this is key to BT’s adoption in the industry
Apple was the first computer company to fully support BT in the OS. BT support was first announced at MWNY ‘02 in the form of a downloadable add-on for MacOS 10.1.x, a joint venture with Sony-Ericsson, and a new piece of software called iSync. iSync was designed to allow you to sync you calendar, address book, and notes with several devices (Palm, .Mac, iPod), among them BT devices. Jaguar fully supported BT by integrating it into the OS
Recent announcements from Apple relating to BT include the release of iSync 1.0 and the new PowerBooks (12’’ and 17’’); both of which have the BT antennas embedded into the casing. Future products from Apple should follow the same trend with BT integration in the hardware.
Demonstrate the following (just show briefly): **Bluetooth System Preference panel when BT device (i.e. DWB-120M) is inserted into USB slot **Bluetooth menu item **Bluetooth File Exchange application in Applications/Utilities folder **Bluetooth development tools in /Development
Just a quick overview of some terminology used to describe BT basic features. As mentioned before ... (read from slid)
So what the heck is a GHz. Flash back to your high school physics course. If you recall, the prefixes indicate the power of ten a number should be raised to. We’re interested in GHz., which is 10^9. So ... 2.4 GHz. is equal to 2,400,000,000 Hz. (”2 billion, 400 million Hz.”)
Remember the EM band? It’s a chart indicating where various forms frequency depended devices reside. 2.4 GHz. is somewhere between the frequencies used for AM/FM radio and Radar. The ISM bands are being used by more and more devices. Among those using the 2.4 GHz. space are ... *Cell phones *802.11b and g *Many cordless phones *Microwaves However, BT has methods to avoid collisions with these other protocols. We’ll talk more about that a little later.
On the speed front is Mbps, short for MegaBITS per second. Not to be confused with MBps, short for MegaBYTES per second. We tend to think in MBps terms since we hear so much about size as it relates to storage capacity. There are 1,048,576 bytes per MB and 8 bits per byte. So 1 Mb is about 10% of a MB (it’s actually ~12%)
A quick chart shows how BT stacks up against other wired and wireless protocols. It’s by far the slowest of the bunch; even slower than USB. However, keep in mind that BT sends very small packets to many different devices seamlessly at the same time. It’s not meant to transfer video or large graphics (although a new version of BT proposed is said to increase bandwidth to 10 Mbps to become comparable to USB).
BT is not meant to replace Airport or Airport Extreme. Those protocols send larger packets and carry a significant amount of network overhead included in TCP/IP packets. By eliminating that source of confusion, BT can focus on becoming easier to use setup from a user perspective. It also explains why BT chips can be produced at such a low cost as compared to other wireless chips solutions.
BT is, as mentioned before, a method to replace wires currently in peripherals. It’s also a method to allow devices that previously could never communicate talk to one another (i.e. PDA and cell phone, cell phone and car, etc...)
First, let’s go over the general idea of how BT devices establish connections with each other. The general concept on which BT rests is the establishment of temporary and spontaneous connections established when devices are within range of each other. The connections employ a master-slave concept (i.e., one master and many slaves serving under that master). Devices are labeled as “discoverable” if they want to be detected by other devices. Non “discoverable” devices essentially implement a cloaking routine that prevents other devices for detecting them if they haven’t already been paired together. The discovering device is labeled the “master” and the discovered device is labeled the “slave”
Assuming both devices are discovered and all things being equal, the devices (a cell phone and laptop) will detect each other. The devices that becomes the “master” and the devices that becomes the “slave” is random (in this case the cell phone becomes the “master”). Once the devices find each other, they perform a simple “sync”, sharing only basic information like the frequency hop phase, hardware ID, and device name if available. This established a basic connection.
Once a basic connection is established, the devices determine if to continue to the next level of the connection phase. The services the slave provides are sent to the master. If the master needs one of the services provided, it establishes a more secure connection through a process called pairing. If two devices are to be “paired”, they share something called a “passkey”. This key is another form of authentication.
Demonstrate the following: **Open the Bluetooth System Preference and show how to search for a device and illustrate how device name is sent after device ID **Show how to pair with a device using “passkey” **Show how device paired now shows up in Bluetooth menu item **Quickly run over options in Bluetooth System Preference
The most fundamental layer of the BT protocol stack is the radio layer. Because BT operated in the crowded 2.4 GHz. frequency space, it is prone to encounter packet loss due to collisions with packets from other popular protocols (802.11b, microwaves, etc...). To minimize the damage these collisions have on the communication between BT devices, BT implements a fast Frequency Hopping (FH) technique and small packet sizes. The baseband is the layer that controls the radio. The baseband handles lower level encryption for secure links and basic packet handling techniques. Two types of links can be established in BT: SCO and ACL links. SCO, or Synchronous Connection Oriented links are meant for synchronous data such as voice. ACL, or Asynchronous Connection Less links are intended for data transmission. The Link Manager Protocol (LMP) layer takes care of piconet management (piconet is a network of BT devices), link configuration, and other security functions. The Hardware Controller Interface (HCI) provides a command interface to the baseband controller and link manager, and access to hardware status and control registers. Essentially this interface provides a uniform method of accessing the Bluetooth baseband capabilities.The HCI exists across 3 sections, the Host - Transport Layer - Host Controller. Each of the sections has a different role to play in the HCI system. The Logical Link Control and Adaptation Layer Protocol (L2CAP) is layered over the Baseband Protocol and resides in the data link layer. L2CAP provides connection-oriented and connectionless data services to upper layer protocols with protocol multiplexing capability, segmentation and reassembly operation, and group abstractions. The service discovery protocol (SDP) provides a means for applications to discover which services are available and to determine the characteristics of those available services. The RFCOMM protocol provides emulation of serial ports over L2CAP. TCS (Telephony Control Protocol Specification) provides a protocol for voice operation over BT.
The BT packet contains three entities, each of which encompasses a key piece of information. The three entities are the Access Code, Header, and Payload. Access Code :used for timing synchronization, offset compensation, paging and inquiry. There are three different types of Access code: Channel Access Code ( CAC ) Device Access Code ( DAC ) Inquiry Access Code ( IAC ) The channel access code identifies a unique piconet while the DAC is used for paging and its responses. IAC is used for inquiry purpose. Header : contains information for packet acknowledgement, packet numbering for out-of-order packet reordering, flow control, slave address and error check for header. Payload : can contain either voice field, data field or both. It it has a data field, the payload will also contain a payload header. There are 13 different types of packets.
To avoid collisions with other 2.4 GHz. products and protocols, BT implements a spread spectrum technique using a fast Frequency Hop (FH) system. This FH system performs 1600 hops per second.
A quick example of the fast FH technique. Using our friend Tigger and Piglet was can illustrate how two devices on different hop phases can find each other and agree upon a common hop phase. Tigger is searching for devices, operating at his own FH phase. Once Piglet enters the picture, they initialize basic communication and decide upon a FH phase.The decided FH sequence is determined by the BT address of the master device. The channel is divided up into time slots where each corresponds to an RF hop frequency; consecutive hops correspond to different RF hop frequencies. The master shall start communication in even-numbered time slots and the slave in odd-numbered time slots.
As mentioned before, a piconet can have only one master and many slaves. In fact, each piconet can have up to 7 “active” slaves and many more low power “parked” slaves. Slaves can become members of multiple piconets, something called a scatternet. The following diagrams illustrate (from left to right) a piconet with two devices, a piconet with more than two devices, and a scatternet.
Bluetooth controller operates in two major states: Standby and Connection . There are seven substates which are used to add slaves or make connections in the piconet. These are page, page scan, inquiry, inquiry scan, master response, slave response and inquiry response . The Standby state is the default low power state in the Bluetooth unit. Only the native clock is running and there is no interaction with any device whatsoever. In the Connection state, the master and slave can exchange packet , using the channel (master) access code and the master Bluetooth clock. Once a link is established, LMP will use SDP to find the services provided on a certain device. If a service desired is available, L2CAP will create a channel to the device. This connection can be used by applications or another protocol if needed.
Demonstrate the following: **Show how complicated BT piconet works (2 x iBook, T68i) **Perform file transfer and sync at same time
talk about voice and data capabilty in passing (asyncronous for data and syncronous for voice)
Bt implements a 128-bit encryption scheme. This can be turned on or off for the transfer of information over the air. However, 128-bit encryption is always on when creating something called a “Link Key.” A “Link Key” is created from a “Passkey” and is sent over the wire instead of the passkey. Link keys can be stored on devices for future connections. Another method for security is to turn off “discoverable” mode on devices. When this mode is turned off, other BT devices will be unable to “find” them using inquiry methods.
talk about future products and implementations of BT
<ul><li>Presented by Andrew Jones </li></ul><ul><li>CWRU Apple Campus Representative </li></ul>Bluetooth In-Depth
<ul><li>Bluetooth (BT) is a short-range wireless protocol designed to create ad-hoc networks </li></ul><ul><li>Operates at 2.4 GHz.; part of the industrial, scientific, and medical band (ISM) of electromagnetic spectrum </li></ul><ul><li>Communication up to 1 Mbps </li></ul><ul><li>Effective range of 30 feet (~10 m) </li></ul>What the %*#@ is it?
<ul><li>Robustness </li></ul><ul><li>Low complexity (to user) </li></ul><ul><li>Low power consumption </li></ul><ul><li>Low cost </li></ul><ul><li>Support for both data and voice </li></ul>Key features of BT
<ul><li>Invented in 1994 by L. M. Ericsson </li></ul><ul><li>Standard named after Harald Blaatand “Bluetooth” II, king of Denmark 940-981 A.D. </li></ul><ul><li>Designed as part of “ubiquitous computing” environment; improvements on previous technology (IrDA) </li></ul>A brief history of BT
<ul><li>BT Special Interest Group (SIG) formed in 1998 </li></ul><ul><li>Version 1.0 of BT open specification released in 1999 </li></ul><ul><li>Adoption BT slow initially due to technical issues and hype, but ... </li></ul>A brief history of BT
<ul><li>Things are changing ... </li></ul>A brief history of BT
<ul><li>Late 1999, 3Com, Lucent, Microsoft, and Motorola joined BT SIG; create Promoters Group </li></ul><ul><li>Mid-2001 BT specification 1.1 released </li></ul><ul><li>Microsoft provides XP support in late 2002 </li></ul><ul><li>BT SIG now supported by 2,000 members; Apple is among them! </li></ul>A brief history of BT
<ul><li>BT support announced at MWNY ‘02 </li></ul><ul><ul><li>Apple sells D-Link USB adapter </li></ul></ul><ul><ul><li>Apple provides Software Development Kit </li></ul></ul><ul><ul><li>iSync software announced </li></ul></ul><ul><li>Jaguar released late August ‘02 with built in BT support </li></ul>Apple’s role with BT
<ul><li>iSync 1.0 released early January ‘03 </li></ul><ul><li>Apple announces PowerBook 12’’ and 17’’ with built in BT support </li></ul><ul><li>Future hardware to include BT? It’s a safe bet! </li></ul>Apple’s role with BT
Wireless Communications 101 <ul><li>As mentioned before, BT has these basic specifications: </li></ul><ul><ul><li>Operates at 2.4 GHz. </li></ul></ul><ul><ul><li>Communication up to 1 Mbps </li></ul></ul><ul><ul><li>Effective range of 30 feet (~10 m) </li></ul></ul>
<ul><li>Just a reminder ... </li></ul><ul><ul><li>10 3 = kilo (k) </li></ul></ul><ul><ul><li>10 6 = mega (M) </li></ul></ul><ul><ul><li>10 9 = giga (G) </li></ul></ul><ul><ul><li>10 12 = tera (T) </li></ul></ul><ul><li>So ... 2.4 GHz. = 2,400,000,000 Hz. </li></ul>2.4 GHz. what?
Where is this in the electromagnetic band? 10 0 10 2 10 4 10 6 10 8 10 10 10 12 10 14 10 16 10 18 10 20 AC wall plug AM radio FM radio Television Cell phones Radar Infrared Visible Ultraviolet X-ray 2.4 GHz. freq.
What’s a Mbps? <ul><li>Mbps = Megabits per second </li></ul><ul><li>We tend to think in MBps (Megabytes) </li></ul><ul><li>1,048,576 bytes per MB </li></ul><ul><li>8 bits per byte </li></ul><ul><li>So after some quick math ... </li></ul><ul><ul><li>1 Mb ≈ 10% of a 1 MB </li></ul></ul>
How does BT stack up to other protocols? Communication Speed in Mbps
What BT is not... <ul><li>BT isn’t a replacement for standard wired or wireless networks </li></ul>
<ul><li>BT is meant to remove wires from your peripherals; similar to role of 802.11x with networking </li></ul>What BT is ... Wired Wireless Network Peripheral Ethernet Firewire/USB Airport Bluetooth
<ul><li>General idea: temporary and spontaneous connections made using master-slave concept </li></ul><ul><li>“Discoverable” devices broadcast services provided to other devices </li></ul><ul><li>The discovering device becomes “master” and discovered device becomes “slave” </li></ul>How does BT work?
<ul><li>Once devices find each other, they “sync” </li></ul><ul><ul><li>frequency hop phase </li></ul></ul><ul><ul><li>Hardware ID </li></ul></ul><ul><ul><li>[Device name] </li></ul></ul>How does BT work?
<ul><li>Once two devices have “synched” ... </li></ul><ul><ul><li>determine services provided </li></ul></ul><ul><ul><li>establish trusted connection if desired; “pairing” </li></ul></ul><ul><ul><li>send “passkey” to validate device </li></ul></ul><ul><ul><li>perform desired service over connection </li></ul></ul>How does BT work?
Living in a 2.4 GHz. world <ul><li>Frequency Hops (FH) are fixed at: </li></ul><ul><li>2402 + k MHz., where k = 0 ... 78 </li></ul><ul><li>BT uses fast FH technique resulting in 1600 hops per second </li></ul>
Living in a 2.4 GHz. world 2.404 GHz. 2.426 GHz. 2.452 GHz. Agree upon hop phase
<ul><li>Piconet: group of devices on common channel (unique hop sequence) </li></ul><ul><li>One master per piconet; up to seven “active” slaves on one piconet </li></ul><ul><li>Slaves can be members of multiple piconets </li></ul>Listen to me! M M S S S S M M S S M
Detailed Explanation of BT Communication “ Inquiry” for devices in range All devices in range respond “ Page” device of interest (sync) Link established LMP use SDP to find services L2CAP channel created RFCOMM/another channel created
<ul><li>BT can handle voice and data </li></ul><ul><li>Two types of communication: SCO and ACL </li></ul><ul><li>Synchronous Connection Oriented (SCO) links are meant for voice </li></ul><ul><li>Asynchronous Connection Less (ACL) links are intended for data transmission </li></ul>Voice and Data
<ul><li>BT employs a 128-bit encryption scheme called Safer+ </li></ul><ul><li>“Passkeys” never sent over the air </li></ul><ul><li>“Passkey” generates 128-bit key called “Link Key” </li></ul><ul><li>“Link Key” used to establish future connections </li></ul><ul><li>Turning off “discoverable” mode prevents others from connecting </li></ul>Keeping Data Safe
<ul><li>BT now found in many common peripherals and devices (PDA, cell phone, computer) </li></ul><ul><li>Automotive industry beginning to implement BT for headsets </li></ul><ul><li>FedEx will soon be using in device for package data </li></ul><ul><li>Estimated BT units shipped to grow from 10.4 million in 2001 to 690 million in 2006 </li></ul>Coming to a _____ near you!
<ul><li>Sony Ericsson Clicker </li></ul><ul><ul><li>control computer with cell phone </li></ul></ul><ul><ul><li>uses AppleScript </li></ul></ul><ul><ul><li>proximity sensor feature </li></ul></ul>Cool Software for Mac http://homepage.mac.com/jonassalling/Shareware/Clicker/
<ul><li>Romeo </li></ul><ul><ul><li>control computer with cell phone </li></ul></ul><ul><ul><li>mouse mode </li></ul></ul>Cool Software for Mac http://irowan.com/arboreal/
<ul><li>Bluetooth SIG </li></ul><ul><ul><li>http://www.bluetooth.org </li></ul></ul><ul><li>Official Bluetooth web site </li></ul><ul><ul><li>http://www.bluetooth.com </li></ul></ul><ul><li>Apple’s Bluetooth section </li></ul><ul><ul><li>http://www.apple.com/bluetooth </li></ul></ul>Resources
<ul><li>Ericsson Bluetooth site </li></ul><ul><ul><li>http://www.ericsson.com/bluetooth/ </li></ul></ul><ul><li>Bluetooth Resource Center </li></ul><ul><ul><li>http://www.palowireless.com/bluetooth/ </li></ul></ul><ul><li>Bluetooth Weblog </li></ul><ul><ul><li>http://bluetooth.weblogs.com/ </li></ul></ul>Resources