Bluetooth Protocol Stack is shown below:-
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
- the lowest defined layer of the Bluetooth specification
2.operating in the 2.4 GHz ISM Band
- 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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