Learning about Bluetooth architecture and Protocols

Deep-Diving-Bluetooth

Bluetooth technology
> bluetooth basic rate/enhanced data rate
 >> High speed
> Low energy 
> Attribute protocol/ generic attribute profile

------------
V2.1 - 2007 + EDR | secure device pairing by button press
V3.0 - 2009 + HS | MAC/PHY
V4.0 - 2010 + LE 

------------
Factsheet -> HS/BR/EDR vs LE
------------
Bluetooth Architecture
------------
BR Only Architecture:-
Serial Port Profile < RFCOMM Protocols < L2CAP < Link Manager < Basic Rate RF

LE Only Architecture:-
Generic Attribute Profile < Attribute Protocol < L2CAP < Link Layer < Low Energy RF
------------
How do these Talking to each other ??  Bcoz Physical layer is different?
Sol. - Dual mode chips > Have commong physical layer > Almost same analog circuitary/slightly different digital circuitary
------------
Bluetooth vs Other Technologies

> Time division multiplexing : Time is divided into 625 micro-s = "slots" VS `FRAME = 2 slots`
> Data is exchanged via Packets lasting one or more slot - like a packet may be 1 slot long or 3 slots long
> Packets = Access Code + Header + Payload
> Introduction of Extended Data rate = Access Code + Header + SYNC(& GUARD & TRAILER) + Payload
------------
Data Exchange Modes
1. Asynchronous Connection-oriented logical transport (ACL)
2. Synchronous Connection-oriented link (SCO), Enhanced SCO (eSCO)

------------
DISCOVERY Process:

Device 1 ==> Sends ID Packets ==> looks for other devices
Device 2 ==> listens (Discoverable mode) ==> When acceptable packet is received, replies
Device 1 can link with 2 OR continue looking for new
When desired device is found, connection process begins

-------------
CONNECTION ESTABLISHMENT:

Device 1 initiates the connection
Device 2 has to accept a connection
Device 1 "INITIATOR" 'pages' the desired device using an ID packet derived from the {LAP} of the desired devices
>>>>>BT_ADDR = NAP[16 bits]+UAP[3 bits]+LAP[24 bits]<<<<<
Device 2 hears ID packet with its address, replies back
--------------
Piconet

> 1 Master ==> 7 active Slaves
> Master controls communication
> No Slave-2-Slave communication
> Master has to ensure not to 'starve' slaves

---------------
Scatternet

> 2+ Piconets
> Master of 1 Piconet is slave of other
> No direct connection bt slaves in one piconet with those in the other

---------------
Interference Management

> Adaptive Frequency Hopping (AFH)
    > Designed to reduce interference bt wireless tech sharing the 2.4 GHz spectrum
    > Works within spectrum to take advantage of the available frequency
    > Detects other devices in the spectrum and avoids frequencies in use
> Provides users with optimal transmission performance even if utilizing other tech in same spectrum

----------------
Asynchronous Connection-Less (ACL)
- Used for data connection
- Throughput is best-effort and is impacted by other factors like no of devices in piconet
- Packets (DM1 & DH1 - 1 slot, AUX1, DM3 & DH3 - 1 slot, DM5 & DH5 - 1 slot)

Synchronous Connection Oriented (SCO)
- Used for voice data
- Utilized reserved timeslots with no retransmission but may use forward error correction
- Four packet types (all single slots : HV1, HV2, HV3 and DV)

Enhanced SCO (eSCO) adds retrasmission
- Basic Rate (BR) packet types: EV3 (1 slot), EV4 and EV5 (3 slot)
- Enhanced Data Rate (EDR) packet types: 2-EV3 (1 slot), 2-EV5 (3 slot), 3-EV3 (1 slot), 3-EV5 (3 slot)

----------------
Power Classes and Approximate Range
- Class 1 : 0dBm to +20dBm (1mW to 100mW) [100 metres] {Needs POWER CONTROL}
- Class 2 : -6dBm to +4dBm (250 microW to 2.5 mW) [10 metres]
- Class 3 : <0dBm (<1mW) [<10 metres]

-----------------
Bluetooth High Speed Technology

- Leverages existing radio technology
  > 802.11 a,b,g,n
  > Backward compatible with legacy Bluetooth devices
- Bluetooth wireless technology
  > Consumes benefit from enhanced data rates w/o changing the way they utilize Bluetooth tech today
- Leverages existing 802.11 device capabilities

-----------------
LOW ENERGY

>