Bluetooth Technology Name- Bittu Kumar Roll No.- A05 Section- E2801 Reg. No.- 10808479 Course code-CSE 001D

An Introduction to BLUETOOTH TECHNOLOGY

One of the first modules (Ericsson) What is Bluetooth? “Bluetooth wireless LAN technology is an open specification for a low-cost, low-power, short-range radio technology for ad-hoc wireless communication of voice and data anywhere in the world.” One of the first modules (Ericsson) A recent module

Cordless Computer

Overview of Bluetooth History What is Bluetooth? Bluetooth is a short-range wireless communications technology. Why this name? It was taken from the 10th century Danish King Harald Blatand who unified Denmark and Norway. When does it appear? 1994 – Ericsson study on a wireless technology to link mobile phones & accessories. 5 companies joined to form the Bluetooth Special Interest Group (SIG) in 1998. First specification released in July 1999.

Technical features Connection Type Spread Spectrum (Frequency Hopping) & Time Division Duplex (1600 hops/sec) Spectrum 2.4 GHz ISM Open Band (79 MHz of spectrum = 79 channels) Modulation Gaussian Frequency Shift Keying Transmission Power 1 mw – 100 mw Data Rate 1 Mbps Range 30 ft Supported Stations 8 devices Data Security –Authentication Key 128 bit key Data Security –Encryption Key 8-128 bits (configurable) Module size 9 x 9 mm

Classification Classification of devices on the basis of Power dissipated & corresponding maximum Range. POWER RANGE CLASS I 20 dBm 100 m CLASS II 0-4 dBm 10 m CLASS III 0 dBm 1 m

Architecture of Bluetooth Bluetooth will support wireless point-to-point and point-to-multipoint (broadcast) between devices in a piconet. Point to Point Link Primary – secondary relationship Bluetooth devices can function as Primary or secondary Piconet It is the network formed by a Primary and one or more secondary (max 7) Each piconet is defined by a different hopping channel to which users synchronize to Each piconet has max capacity (1 Mbps) P s s P

Piconet Structure All devices in piconet hop together. Primary Active Slave Parked Slave Standby All devices in piconet hop together. Master’s ID and Primary’s clock determines frequency hopping sequence & phase.

Ad-hoc Network – the Scatternet Inter-piconet communication Up to 10 piconets in a scatternet Multiple piconets can operate within same physical space This is an ad-hoc, peer to peer (P2P) network

Bluetooth layer

Radio Layer Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops up the data being sent and transmits chunks of it on up to 79 frequencies. Reduce interference with other devices. Pseudorandom hopping. 1600 hops/sec- time slot is defined as 625 microseconds, it means each device changes its modulation frequency 1600 times per second. Packet 1-5 time slots long.

**Baseband layer--Physical link** Two type of links can be created between a primary and secondary: SCO links and ACL links. SCO- A synchronous connection oriented link used when avoiding latency(delay in data delivery) is more important than intergrity (error free delivery). In a SCO link, a physical link is created between the primary and secondary by reserving specific slot at regular intervals. The basic unot of connection is two slot, one for each direction. If the pocket is damaged, it never retransmitted. ACL- an asynchronous connection link (ACL) is used when data intergrity is more important than avoiding latency. In this type of link, if a payload encapsulated in the frame is corrupted, it is retransmitted. FRAME FORMATE- . Frame in baseband layer can be one of three types:- one slot, three slot , or five slot. . A slot is 625 micro-sec, however, in one slot frame exchange, 259 micro-sec is needed for hopping and control mechanism. This means that a one slot frame can last only 625-259 or 366 micro-sec. with a 1 MHz bandwidth and 1bit\sec, the size of a one slot frame is 366 micro-sec.

  Frame formate Data in piconet is encoded in packets. The general packet format is shown below: 1. Access code- This 72-bit field normally contains synchronization bits and the identifiers of the primary to distinguish the frame of one piconet from another. 2. Header- this 54-bit field is a repeated 18-bit pattern. Each pattern has following subfield. .

A). Address- The 3-bit address can define up to seven secondary (1 to 7). If the address is zer0, it used for broadcast communication primary to all secondary. B). Type- The 4 bit-type subfield defines the type of data coming from the upper layer. C). F- this 1-bit subfield is for flow control. D). A- The 1 bit field for acknowledgement. E). S- The 1-bit subfield holds a sequence number. G). HEC- the 8-bit header error correction subfield is a checksum to detect error in each 18-bit header section. The header has three identical 18-bit section. The receiver compares these three section bit by bit. If each of the corresponding bits is the same, the bit is accepted. If not , the majority opinion rules. This is a form of forward error correction. 3. Payload- This subfield can be 0 to 2740 bits long. It contains data or control information from the upper layers.

L2CAP Service provided to the higher layer: L2CAP provides connection-oriented and connectionless data services to upper layer protocols Protocol multiplexing and demultiplexing capabilities Segmentation & reassembly of large packets L2CAP permits higher level protocols and applications to transmit and receive L2CAP data packets up to 64 kilobytes in length.

Core Bluetooth Products Notebook PCs & Desktop computers Printers PDAs Other handheld devices Cell phones Wireless peripherals: Headsets Cameras CD Player TV/VCR/DVD Access Points Telephone Answering Devices Cordless Phones Cars

Security Security Measures Link Level Encryption & Authentication. Personal Identification Numbers (PIN) for device access. Long encryption keys are used (128 bit keys). These keys are not transmitted over wireless. Other parameters are transmitted over wireless which in combination with certain information known to the device, can generate the keys. Further encryption can be done at the application layer.

A Comparison WLAN

Bluetooth vs. IrD Bluetooth IrD Point to Multipoint Point to point Data & Voice Easier Synchronization due to omni-directional and no LOS requirement Devices can be mobile Range 10 m IrD Point to point Intended for Data Communication Infrared, LOS communication Can not penetrate solid objects Both devices must be stationary, for synchronization Range 1 m

Future of Bluetooth Success of Bluetooth depends on how well it is integrated into consumer products Consumers are more interested in applications than the technology Bluetooth must be successfully integrated into consumer products Must provide benefits for consumer Must not destroy current product benefits Key Success Factors Interoperability Mass Production at Low Cost Ease of Use End User Experience

Summary A new global standard for data and voice Eliminate Cables Low Power, Low range, Low Cost network devices Future Improvements Master-Slave relationship can be adjusted dynamically for optimal resource allocation and utilization. Adaptive, closed loop transmit power control can be implemented to further reduce unnecessary power usage.

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