BLUETOOTH TECHNOLOGY
•introduction •technical aspects •stack protocol •applications •competing technologies •conclusions
INTRODUCTION what is bluetooth? •it is a cable-replacement technology •Automatic communication between various devices within a small area
genesis: •conceived initially by Ericsson •it was named after Danish Viking and King, Harald Blatand who had blue teeth. •Later the SIG formed to oversee the development and standardisation of the technology.
TECHNICAL ASPECTS
•bluetooth is based on low cost,short-ranged radio link,operates in the 2.4GHz area of spectrum, and provides a range of 10 metres. •Connections can be point-to-point or multipoint. •Devices connected to each other, they form a personal area network (PAN)called the piconet. •Each piconet can have a master, and up to 7 active and 255 parked slaves. •Different piconets are connected using a common device and such networks are called scatternet.
A piconet
Avoiding interference: •To accommodate interference, bluetooth uses a tehnique called spread-spectrum frequency hopping. •a device will use 79 individual, randomly chosen frequencies within a designated range, changing frequencies 1,600 times every second
power conservation: it has 3 modes:hold: no data is transmitted Sniff: The sniff mode, applicable only to slave units, the slave does not take an active role in the piconet, but listens at a reduced level.
Contd.
Park: Park mode is a more reduced level of activity than the hold mode In this state, they do not have MAC addresses, but only listen enough to keep their synchronization with the master and check for broadcast messages. •Every bluetooth device has a 48-bit BDA(BlueTooth Device Address) burned into its ROM.
STACK PROTOCOL The protocols are: Radio:modulates and demodulates data for transmission and reception , defines the requirements for a Bluetooth transceiver operating in the 2.4 GHz ISM band. Baseband:it defines the process by which bluetooth devices search for each other and mode of connection between them.
contd. LMP:The Link Manager Protocol(LMP) is used for link set-up and control,encryption of data,cutting of the link if authentication fails, adjustment of tranmission power.
L2CAP:Lgical Link Control And Adaptation Protocol(L2CAP) supports higher level protocol multiplexing, packet segmentation and reassembly, and the conveying of quality of service information.
Contd.
HCI:The Host Contol Interface(HCI) defines a standard access mechanism for higher layers to access the services of the lower layers. SDP:The Service Discovery Protocol(SDP) provides a means for applications to discover which services are provided by or available through a Bluetooth device. It also allows applications to determine the characteristics of those available services
APPLICATIONS:
•tremendous potential in moving and synchronizing information in a localized setting. •The Bluetooth technology connects all your office peripherals wirelessly. •Bluetooth allows us to have three way phones •Automatic Message Delivery. •Have automatic synchronization of your desktop, mobile computer, notebook and mobile phone. •Upon arriving at your home, the door automatically unlocks for you, the entry way lights come on, and the heat is adjusted to your pre-set preferences.
COMPETING TECHNOLOGIES
infra-red: •Uses infra-red beam to transfer data. •IrDA(Infra-red Data Association)is an organisation that maintains the standard for communication via infra-red. •Devices need to have a line of sight between their ports to function. •Ports must face without any obstruction. •It is half-duplex and point-to-point standard and data rate is very slow.
Contd.
Wifi: •Wireless Fidelity is a standard that promises mobility while offering data rates comparable to LAN. •Adopted when there is demands for high speed on the move •But it is expensive •Drains batteries much quicker •Difficult to provide security. •It is difficult to control access to the network.
CONCLUSION:
It is set to revolutionize the personal connectivity market by providing freedom from wired connections.Technology will eventually sky rocket. With a low cost to consumers, bluetooth seems like a logical answer to wireless communication.But inspite of promises,consumers avoid it due to cost.If a killer application appears it could remedy the situation by making people more willing to buy it, but no one has figured one out yet.