written 8.4 years ago by | • modified 3.1 years ago |
Mumbai University > Computer Engineering > Sem6 > Mobile Communication and Computing
Marks: 10M
Year: May 2015
written 8.4 years ago by | • modified 3.1 years ago |
Mumbai University > Computer Engineering > Sem6 > Mobile Communication and Computing
Marks: 10M
Year: May 2015
written 8.4 years ago by |
Bluetooth is a universal radio interface operating in the ISM band.
It provides ad-hoc wireless connectivity between portable electronic devices located at a short range from each other.
The Bluetooth protocol stack contains various layers like radio layer, baseband layer, L2CAP layer etc. Let’s discuss the baseband layer in depth:
The following figure describes the components of a Bluetooth packet at baseband layer.
The baseband is the digital engine of a Bluetooth system. It is responsible for
Access code:
An access code consist of
Packet header:
AM address | 3-bit | Also called as Active Member address, it represents the active address of the slaves which are assigned temporarily in a piconet. It’s a 3-bit value |
---|---|---|
Type | 4-bit | It determines the type of packet. It is based on the type of connection (seen in Payload section) the applied coding rate, symmetry/asymmetry of connection. |
Flow | 1-bit | Its meant to implement a flow control mechanism. If flow=0 ; Asynchronous data → Stop flow of data If flow=1 ; Synchronous data → Resume the flow |
ARQN SEQN |
1-bit 1-bit | ARQN stands for acknowledgement number and SEQN stands for sequence number. They are used for packet acknowledgement purposes. |
HEC | 8-bit | The Header Error Check (HEC) is used to protect the packet header |
Payload:
Upto 343 bytes of payload data can be transferred via a single packet.
A basic requirement for Bluetooth was to provide both voice as well as data transmission facility.
Depending on the requirement (i.e. voice or data ) we classify the links into two which are:
Synchronous Connection Oriented (SCO):
Used for supporting symmetrical, point-to-point, and circuit-switched connection which are meant for voice transmissions.
They are realized by reserving two slots at fixed slots intervals for forward and reverse transmission.
Asynchronous Connection-less (ACL):
These links are used for bursty data transmissions
It supports packet switched, symmetrical and asymmetrical conditions.