Features of bluetooth technology Essay

The logo for Bluetooth is establish on Runes surrounding the legend of Harald Bluetooth. Bluetooth the technology is based on communications central to mans own personal space. Fundamentally Bluetooth operates at bottom the Industrial, Scientific and Medical (ISM) band at 2. 4 gigacycle per second. It is a short- ordain wireless communication standard defined as cable heir for a Personal Area Network (PAN) (see Bluetooth. Grolier Encyclopedia of Knowledge, pp. 87-94). Figure 1 is the Bluetooth Logo. A cable replacement standard has been defined because cables limit mobility of the consumer they ar cumbersome to carry around, are easily lost or broken. a good deal connectors are prone to difficult to diagnose failures or are proprietary. To overthrow these limitations Bluetooth is casted to be light and portable. It can be embedded to murder the riggers of physical knocks and shocks. It includes standards and protocols to make it mobile, robust, reliable and not limited to one producer (see Bluetooth. Grolier Encyclopedia of Knowledge, pp. 87-94). The operating band also fits the goals of Bluetooth, imposing requirements as a cable replacement. The cost needs to be comparable with cable. Reductions can be achieved by operating in the licence free 2.4 GHz ISM band, keeping backward compatibility wherever possible lowers the cost of possession by avoiding upgrades and having a relaxed intercommunicate specification enables single chip interconnected circuit solutions. It also needs to be as reliable and bouncy as cable and cope with errors and degradation caused by interference. For mobile devices it must(prenominal) be compact, lightweight, low power and easy to use (see Bluetooth. Grolier Encyclopedia of Knowledge, pp. 87-94). A. 1 Frequency Hopping We have addressed the reasons for the Bluetooth without delving into the nuts and bolts of the technology to discover how it operates.For the absolute majority of countries the ISM band used by Bluetooth is gettable from 2. 40-2. 4835 GHz, although some countries chat restrictions. In this band Bluetooth uses Frequency Hopping Spread Spectrum (FHSS) techniques in order to meliorate its immunity from interference (see J. labour and C. F. Sturman, Bluetooth conjoin Without Cables, Prentice Hall). In unexclusive countries the radios hop in pseudo random chronological successions around all available channels, this equates to 79 RF channels with a channel spacing of 1 MHz.Starting at a base frequency of 2402 MHz thus the frequency of the channels, f, can be expressed as f =2402 + n MHz where, n, is the channel number with an integer value in the range of 0 to 78. In restricted countries a limited frequency hopping schemes with skilful 23 channels is used and is catered for in the Bluetooth specification. Both hopping schemes have a 1 MHz channel spacing making it possible to design a simple radio interface whereby the baseband only has to specify a channel number and the radio multiplies this up to the appropriate frequency starting prison term (see J.Bray and C. F. Sturman, Bluetooth Connect Without Cables, Prentice Hall).In this FHSS scheme there are 1600 record hop per second, which is a hop every 625 s. Part of this hop timing is interpreted up by the guard time of 220 s allowing the synthesizer time to settle. The frequency hopping implements time division multiplexing as shown in Figure 2. The priming of the scheme has the Master device transmitting in the first 625 us slot, k, and here the Slave receives. In the next slot k = 1 the Slave is permitted to transmit and the master listens (see J.Bray and C. F. Sturman, Bluetooth Connect Without Cables, Prentice Hall).Figure 2 Frequency Hopping, master and slave interact on corresponding slots The radio must be able to retune and stabilise on a sunrise(prenominal) frequency within tight time constraints. This is pushed further when establishing a link the hop rate can be shortened to every 312. 5 u s. As the radios are constantly hopping to different radio channels, this ensures that packets affected by interference on one channel can be retransmitted on a different frequency channel.To further enhance resilience both(prenominal) ARQ (Automatic Repeat reQuest) and FEC (Forward Error Correction) form part of the specification (see J. Bray and C. F. Sturman, Bluetooth Connect Without Cables, Prentice Hall). One drawback with the normal hop sequence is the time interpreted for production testing. Bluetooth ensures adequate frequency coverage with a test sequence allowing the radios to be tested at a faster rate (see J. Bray and C. F. Sturman, Bluetooth Connect Without Cables, Prentice Hall).