1. BLUETOOTH :wireless technology standard for exchanging data over short distances (using short-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz) from fixed and mobile devices, and building personal area networks (PANs).:
2. ROLE OF TDMA IN BLUETOOTH Bluetooth uses a form of TDMA that is called TDD-TDMA (timedivision duplex TDMA). TDD-TDMA is a kind of half-duplex communication in which the secondary and receiver send and receive data, but not at the same time (halfduplex)
3. Single-Secondary Communication If the piconet has only one secondary, the TDMA operation is very simple. The time is divided into slots of 625 microsec. The primary uses even numbered slots (0, 2, 4, ...); the secondary uses odd-numbered slots (1, 3, 5, ...). TDD-TDMA allows the primary and the secondary to communicate in half-duplex mode.
4. Multiple-Secondary Communication The process is a little more involved if there is more than one secondary in the piconet. the primary uses the even-numbered slots, but a secondary sends in the next odd-numbered slot if the packet in the previous slot was addressed to it. All secondaries listen on even-numbered slots, but only one secondary sends in any odd-numbered slot.
5. 8 devices can communicate within coverage of about 10 meters With latest class of Bluetooth devices distance coverage of about 100 meters are also achievable
6. Master and slave stations communicate with each other using time slots. The master defines the time slot of 625us(microsec)
7. duplex communication links where uplink is separated from downlink by the allocation of different time slots in the same frequency band transmission scheme that allows asymmetric flow for uplink and downlink data transmission
8. Radio-Frequency Identification (RFID) is the use of radio waves to read and capture information stored on a tag attached to an object. A tag can be read from up to several feet away and does not need to be within direct line-of-sight of the reader to be tracked.
9. USES:
10. Access management Tracking of goods Tracking of persons and animals Toll collection and contactless payment Machine readable travel documents Smartdust (for massively distributed sensor networks) Tracking sports memorabilia to verify authenticity Airport baggage tracking logistics[21] Timing sporting events
11. Access control RFID antenna for vehicular access control RFID tags are widely used in identification badges, replacing earlier magnetic stripe cards. These badges need only be held within a certain distance of the reader to authenticate the holder. Tags can also be placed on vehicles, which can be read at a distance, to allow entrance to controlled areas without having to stop the vehicle and present a card or enter an access code
