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Explain Bluetooth Protocol Stack?

Subject: Advanced Network Technologies

Topic: Emerging Wireless Technologies

Difficulty: High

1 Answer
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Bluetooth Protocol Stack is shown below:-

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Layers

1.Bluetooth Radio

2.Baseband

3.LMP (Link Manager Protocol)

4.HCI (Host Controller Interface)

5.L2CAP (Logical Link Control and Adaptation Protocol)

6.RFCOMM (Radio Frequency Communication)

7.SDP (Service Discovery Protocol)

Bluetooth Radio

  1. the lowest defined layer of the Bluetooth specification

2.operating in the 2.4 GHz ISM Band

  1. accomplishes spectrum spreading by frequency hopping (FHSS) from 2.402 GHz to 2.480 GHz

Bluetooth Radio

3 different power classes

Power Class1: long range (100m,100mW)

Power Class2: mid range (10m,1-2,5mW)

Power Class3: short range (0.1-10m,1mW)

signal strength adjustment

Baseband

the physical layer of the Bluetooth that provides

Error correction

Flow control

Hopping sequence

Security

hopping through 79 channels

data is divided in packets

access code: e.g. timing synchronization

header: e.g. packet numbering, flow control, slave address

payload: voice, data or bot

Security Modes non-secure encryption enforced by application layer encryption enforced by link layer

For devices trusted device untrusted device For services require authorization and authentication open to all devices

Audio

two codes: PCM and CVSD

both at 64kbit/s

synchronous connection oriented(SCO) links

time-critical

no retransmission

errors appear as background noise

LMP (Link Manager Protocol)

it provides authentication, link setup and link configuration including power surveillance

it takes place as a service provider

it communication with LM PDUs (protocol data units)

HCI (Host Controller Interface)

it provides a command interface to baseband ccontroller and link manager

Also to hardware status, control and event register

Bluetooth defined Host Controller Transport Layers

L2CAP (Logical Link Control and Adaptation Protocol)

it provides a connection-oriented and connectionless service to upper layer

it protocols with quality-of-service functions using multiplexing, segmentation and reassembly

Two link types defined in Baseband layer: 1. SCO (synchronous connection-oriented) 2. ACL (asynchronous connection-less)

RFCOMM (Radio Frequency Communication)

Supports up to 60 simultaneous connections

Differentiates between two device types:

Type 1: communication end points (e.g. printer or heads

Type 2: devices which are part of communication (e.g. modems)

But in the protocol itself no distinction is made.

Service discovery protocol (SDP):

it handles device information, services, and queries for service characteristics between two or more Bluetooth devices

Host Controller Interface (HCI):

it provides an interface method for accessing the Bluetooth hardware capabilities.

TCS BIN (Telephony Control Service):

it is bit-oriented protocol that defines the call control signaling for the establishment of voice and data calls between Bluetooth devices.

OBEX(OBject EXchange) :

Session-layer protocol for the exchange of objects, providing a model for object and operation representation.

WAE/WAP:

Bluetooth incorporates the wireless application environment and the wireless application protocol into its architecture

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