So now let us discuss what is bluetooth ? Bluetooth is widely used short range communication, which consumes low power and is low cost. Bluetooth will allow us to communicate between two devices with out need of any wires or preexisting network connections. We can exhange information between tehm with out any complex network establishment. You can see this bluetooth in Pcs, mobile devices, listening to music, printers, browsing, attending phone calls, car kits, infotainment systems. Bluetooth is defined as WIRELESS PERSONAL AREA NETWORK(WPAN) Technology.

Bluetooth Special Interest Group (SIG) is a non profit association which is privately held. Bluetooth SIG does not make or manufacture or it will not sell any bluetooth products, the job of lbuetooth SIG are: ->create publish and maintain specifications -> profiles spec documentation -> bluetooth enhancements Initially Bluetooth was developed by Ericsson labs, later Bluetooth SIG was founded by memebers which include Ericsson, intel, IBM, NOKIA, Toshiba, Apple, Lenovo, Microsoft

BLUETOOTH SIG mandates that all the bluetooth devices hsould undergo qualification before they are launched into market. So why this SIG qualificaion is needed for bluetooth means there are multple vendor who will be selling bluetooth devices for example your laptop might use a bluetooth chip from intel company and your head set may use the bluetooth chip from qualcomm and they shoiul be able to communicate with out any issue, that means there is itneroperability between them right this is main idea of SIG qualification.

Now let us discuss bluetooth basics, bluetooth supports AdHoc networks so there is no need of any pre existing network between two devices, the connection is established dynamically, means devices will come in a particualr range establish connection and thn disconnect and can move out of hte range. Classic bluetooth supports 10mtrs but in Bluetooth Low energy we have feature of Long distance data transfer.

Bluetooth Version Evolution

there are two types of data rates in bluetooth Basic Data Rate and Enhanced Data Rate. In bluetooth basic data rate it support 721Kbps and in enhanced data rates it will support till 2.1Mbps. Now let us see frequency in which bluetooth operates. Bluetooth will operate in 2.4GHz ISM band, here ISM will stand for Industry scientify and medical radio band, this band is unlicensed band globally and can be used in any country with out taking any permissions from any goveremtn organization. As it is unlicened specturm any application like wifi, remote control devices and other 2.4Ghz application run here. As there are multiple 2.4Ghz applications running there will chance of interference, to handle thsi interference we will use something called as FHSS(Frequency Hop spread spectrum) so now let us see what is frequency hop spread specturm? Instead of sending data in single channel continuously there are set of frequencies and radio will hop into different frequencies rapidly it iuses a random pattren to swtich between different frequenies.

Parameter Simple Explanation Connection Type Uses Frequency Hopping Spread Spectrum (FHSS) → changes frequency to avoid interference Frequency Band 2.4 GHz ISM band (2400 – 2483.5 MHz) Frequency Hopping 1600 hops/sec across 79 channels (each 1 MHz wide) Modulation GFSK (Gaussian Frequency Shift Keying) Output Power 1 mW to 100 mW Transmit Power Normal: 0 dBm (~1 mW), Max: 20 dBm (~100 mW) Receiver Sensitivity Can detect signals up to -70 dBm Data Rate BR: 721 kbps, EDR: 2.1 Mbps, HS: 24 Mbps Range Typically 10 m to 100 m Topology Piconet → 1 Master + up to 7 Slaves (max 8 devices) Voice Channels Supports up to 3 voice channels Authentication Key 128-bit (device verification) Encryption Key 8 to 128-bit (data protection) Line of Sight Not required Applicability Works worldwide (uses unlicensed band)