1. Short-Range Radio Frequency Networking
B. Ramamuthy
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2. Purpose
Study personal area network PAN and related standard in bluetooth
Based on java.sun.com Bluetooth API overview, design and development.
Other sources: Colouris text and palo wireless bluetooth resource center.
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3. Introduction
Bluetooth is protocol for short range, frequency hopping radio link between devices.
Devices such as phones, PDAs, medical devices that are bluetooth-enabled.
Based on Industrial, Scientific and Medical (ISM) frequency band.
Unlicensed and globally available.
Originally from Ericsson; bluetooth named after a Nordic king instrumental in integration of Scandinavian countries.
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4. Figure 3.18 A typical NAT-based home network
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5. Figure 3.22 IEEE 802 network standards
IEEE No.
Name
Title
Reference
802.3
Ethernet
CSMA/CD Networks (Ethernet)
[IEEE 1985a]
802.4
Token Bus Networks
[IEEE 1985b]
802.5
Token Ring Networks
[IEEE 1985c]
802.6
Metropolitan Area Networks
[IEEE 1994]
802.11
WiFi
Wireless Local Area Networks
[IEEE 1999]
Bluetooth
Wireless Personal Area Networks
[IEEE 2002]
ZigBee
Wireless Sensor Networks
[IEEE 2003]
802.16
WiMAX
Wireless Metropolitan Area Networks
[IEEE 2004a]
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6. Details Radio technology Protocol stack Interoperable profiles
How does the technology work?
How is the technology used?
Sample APIs to work with bluetooth:
javax.bluetooth; javax.obex (for object exchange)
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7. Radio technology 2.5Ghz ISM band
The bluetooth devices in a proximity form a piconet comprising a master and upto 7 devices.
Piconets can connect, the master in a piconet can provide a bridge.
Global and unlicensed.
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8. Protocol Stack Protocol stack provides
a number of higher level APIs for service discovery and serial IO simulation,
lower-level protocols for packet segmentation and reassembly,
protocol multiplexing and QoS
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9. Bluetooth Protocol Stack
Application
Java API for Bluetooth wireless technology (JSR-082)
WAP
UDP/TCP IP
PPP
OBEX
Bluetooth Host
Controller Stack
(software)
Service discovery protocol (SDP)
RFCOMM (serial port emulation)
Logical link control & Adaptation Protocol (L2CAP)
Host controller interface (HCI)
Host Controller Interface Firmware
Link Manager protocol (LMP)
Bluetooth Host Controller
Firmware + Hardware
Baseband Link Controller (LC)
Bluetooth Radio
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10. Typical application Scenarios
Bluetooth application can be either server or client
Peer-peer exposing both client and server functionality
Application need not be in Java
However J2ME-based devices can avail of the bluetooth API.
Though we discuss Java-based API here, MS Vista has a WS based API for devices.
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11. Application activities
java.sun.com
Bluetooth intro
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12. Discovery
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13. Bluetooth clients
DiscoveryAgent support discovery of services and devices.
Clients wanting to be notified should implement and register Discovery Listener interface.
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14. Service/device discovery
A similar sequence
can be assumed for device
Discovery.
Services have a UUID
There is LocalDevice
And RemoteDevice
APIs to control the devices.
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15. Service discovery (contd.)
Once the local device has discovered at least one remote device, it can begin to search for available services –
Bluetooth applications it can use to accomplish useful tasks.
Because service discovery is much like device discovery, DiscoveryAgent also provides methods to discover services on a Bluetooth server device, and to initiate service-discovery transactions
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16. Serial Port
The RFCOMM protocol, which is layered over the L2CAP protocol, emulates an RS-232 serial connection.
The Serial Port Profile (SPP) eases communication between Bluetooth devices by providing a stream-based interface to the RFCOMM protocol. Some capabilities and limitations to note:
Two devices can share only one RFCOMM session at a time.
Up to 60 logical serial connections can be multiplexed over this session.
A single Bluetooth device can have at most 30 active RFCOMM services.
A device can support only one client connection to any given service at a time.
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17. Interoperable Profiles
Profiles have been developed to manage cross-platform interoperability among different manufacturer’s products.
They describe how implementations of user models have to be accomplished.
Lets examine the bluetooth profile as provided by palowireless.
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18. Profiles
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19. How does it work? Bluetooth frame structure
bits: 72 18
Access code
Header
copy 1
Header copy 2
copy 3
Data for transmission
bits: 3 1 4 8
Destination
Flow
Ack
Seq
Type
Header checksum
Address within
Piconet
= ACL, SCO,
poll, null
Header
SCO packets (e.g. for voice data) have a 240-bit payload containing 80 bits of data triplicated, filling exactly one timeslot.
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20. Server operation
Construct a URL that indicates how to connect to the service, and store it in the service record
Make the service record available to the client
Accept a connection from the client
Send and receive data to and from the client
The URL placed in the service record may look something like:
btspp:// A1B1C1D1E100:5
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21. Client operation
To set up an RFCOMM connection to a server the client must:
Initiate a service discovery to retrieve the service record
Construct a connection URL using the service record
Open a connection to the server
Send and receive data to and from the server
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22. Uses of Bluetooth Some are from Accenture: Wiring the wired
Locating lost items
Activity sensing + auditing
Environmental control
Simple transactions
Medical applications are unlimited
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