Bluetooth Connection GFSK

Bluetooth Connection GFSKBACKGROUND OF BLUETOOTH TECHNOLOGYBluetooth was originally organize by the fol deplorableing five entitiesIBMINTELERICSSONNOKIATOSHIBAThe initial five kick in magnanimous to well over a thousand companies at this point and the image is increasing. Though Bluetooth is not quite as popular as 802.11, in that location are number of applications for a wide array of divergent radio receiver doojiggers.For interesting background where exactly Bluetooth get its progress to? Contrary to what your tooth doctor might think it is not from eating blueberries. The actual origin of this shape is formed from a tenth century S placedinavian king whose name was HARALD BLUETOOTH. The companionship is that in his real life he managed to unite some(prenominal) dispa set kingdoms under one area. The idea was to make Bluetooth encompass a kingdom of divergent devices and to create a convergence of many another(prenominal) different devices under the umbrella of one global specification.1.2 WHAT IS BLUETOOTH WIRELESS TECHNOLOGY?Bluetooth radio receiver is an open specification for a low-cast , low power, short-range radio engineering for ad hoc tuner communication of representative and entropy any where in the world. Lets examine to each one of these attributesAn open specification means that the specification is in public available and royalty free Short range radio engineering science means device washstand communicate over the air utilise radio waves at a distance of 10 meters. With higher transmission system power the range increases to approximately 100 meters.Because communication is with in a short range, the radios are low power and are suited for portable, battery-ope rankd devices.Bluetooth radiocommunication technology supports twain voice and data, allowing devices to communicate either type of field of study2. BLUETOOTH MODULATION2.1 Modulation IntroductionBluetooth uses Gaussian absolute absolute frequency shift ke ying (GFSK). much than explicitly, Bluetooth 0.5 BT Gaussian filtered frequency shift keying (2FSK) also referred to as double star frequency shift keying (BFSK) at one M symbols/s with a transfer spacing of 1MHz. Since lonesome(prenominal) dickens frequencies are used one fleck is one symbol (i.e. one indicates a positive frequency deflection (normally 157.5 kc) from the newsboy, and a zero indicates a negative frequency deviation (normally 157.5 KHz) from the carrier).The throw shows that amplitude versus season as well as constellation plat plot of 2FSK transition that is used for Bluetooth. The frequency deviation range is surrounded by cxl 175 KHz.2.2 Summary of Bluetooth modulation requirementsTo receive Bluetooth qualification, a radio must have the following modulation characteristicsGFSK with BT at 0.5 type tramp of 1 mega symbols per second (Ms/s), corresponding to a data rate of 1 Mb/s modulation index beta mingled with 0.28 0.35double star 1 with a posit ive fd and 0 with a negative fdSymbol timing better than +20, -20 parts per million (PPM)Zero crossing illusion not greater than 1/8 of a symbol diaphragmThe fd corresponding to a 1010 sequence to be at least 80 % of fd corresponding to a 00001111 sequenceMinimum fd equal to 115 KHzMost of the previous modulation characteristics are self explanatory buy food perhaps the last two. If the modulation index is between 0.28 0.35, then comparison 3.18 tell us that the corresponding fd must be between 140 175 KHz. This can be considered a energize state fd for a long sequence of binary ones or zeroes. Due to the ISI inherent in GFSK its possible that fd may not micturate its upper limit value for a binary sequence that alternates between 1 0. The specification requires that fd under these conditions reach at least 115 KHz, which is about 80 % of the minimum steady state fd of 140 KHz.2.3 Bluetooth data Rates and Data PacketsThe theoretical maximum data rate is 1 Mbps, but due to overhead, the maximum realizable asymmetric data rate is reduced to 723.2 Kbps. This is also a dapple misleading because the reverse link has a much lower data rate. The table shows is a summary of the possible data rates for the sundry(a) mail boat sizes.The information is transmitted in a packet in a time slot. Each time slot corresponds to an RF skip over frequency. A packet of information can be transmitted in one time slot, terzetto time slots, or five time slots. Naturally, a five slot packet carries more information than a three slot packet, which carries more than a one slot packet. Data high rate (DH) masters higher data rates by using less error counterbalanceion in the packets. Data medium (DM) rate achieves a lower bit error rate probability by using more error correction in the packets. A Bluetooth packet is shown in the go in.2.4 Bluetooth Modulated SignalA modulated signal can be denoted asWhere fc is the carrier frequency, T is the bit period, h is the modul ation index and x(t) is the input of the modulator. The above equation can be viewed as the output of a voltage controlled oscillator with an input of x(t). In FSK modulation, x(t) is a binary signal whereas in GFSK modulation, the binary signal is first passed through a low pass Gaussian filter to produce x(t). This is shown in beneath figure.GFSK modulation is determined by two parameters the modulation index (h) and the bandwidth of the Gaussian filter. The Gaussian filter is usually characterized by the bandwidth-time product (BT), which is equal to the 3-db bandwidth of the Gaussian filter (B) times the bit period (T).In Bluetooth the bit rate is 1Mb/s, BT is 0.5 in the modulation index varies from 0.28 to 0.35, the figure above shows the simulated spectrum of a Bluetooth signal.Note that the well known Gaussian minimum shift keying (GMSK) is a special case of GFSK in the modulation index 0.5.2.5 Frequency HoppingThe forcible connection of Bluetooth uses frequency jumpping a t 1 MHz skim at the actual carrier is spread spectrum modulated. This is known as frequency hop spectrum and is used to improve immunity from interference principal(prenominal)ly from IEEE 802 WiFi wireless fidelity shares the alike(p) spectrum as other users of the ISM band for ideal transitorily operated microwave ovens.There is a fundamentally sound reason for this approach. wireless fidelitys wage significantly more bandwidth than 1 MHz and employ SS techniques, in which a pseudo-random code is used to modulate the information transmitted. At the receiver the same pseudo-random code has to be available to de-modulate it successfully called co-relation. As a result, many WLANs using different pseudo codes can transmit simultaneously without rough-cut interference. The Bluetooth frequency-hop system appears as an un-correlated noise like signal to a WLAN receiver and what is more its signal energy is spread over the faultless band of the WLAN by the de-correlated demodu lation process. SO in practice plebeian interference amounts lonesome(prenominal) to a raised noise floor for some(prenominal) systems. A raise noise floor simply reduces the available carrier to noise and hence reduces the range possible. This is the chief(prenominal) effect of mutual interference. An excommunication can occur when signals are so strong because of the close proximity of the antennas, that they overwhelm a receiver.Bluetooth frequency rate is chosen to be 1600 hops per second with a 625 us dwell time per hop. The minimum soprano time of 625 us corresponds to a single time slot. Part of this hop timing is taken up by the guard time 220 us allowing the hardware based frequency synthesizer time to settle. The transmission impart is derived from the time slots, spread over 79 or 23 frequencies. The frequency hoping scheme uses time division quintuplexing (TDMA), as illustrated in the figure, where the frequency pace n=1MHz.2.6 PiconetsA piconet is formed by tw o or more devices discover each other and begin to communicate. A piconet can have up to eight devices, with one device acting as a master and the rest acting as slsaves. The first device initiates transmission becomes the master, although the specification provides for a master and slave unit to exchange roles. A specific frequency-hopping sequence is used by all devices in spite of appearance each piconet. The figure shows the simplest example of a piconet. In the figure, a cell resound is downloading the address book and telephone number information to the users laptop computer.In this example the laptop acts as the master. The application software running on the laptop contacts the cell phone when it is at bottom range, and requests that it synchronize its database with the one stored on the laptop.As stated earlier a single piconet can have up to eight devices. The reason for this limit is simpleThe address is only three bit long. This means that in binary only the value of 0 7 can be stored in the address field. The master has no address but zero is reserved for broadcast messages so the only addresses remaining for use by slaves are 1 7. However, a device can participate in two different piconets called a scatternet. The figure shows an example of a larger piconet, in which one master controls multiple slaves in a piconet.You can see that its possible to link various(a) devices in a piconet. You can download digital images from your digital tv camera to the laptop, use more than one Bluetooth-enabled cell phone to place voice calls and even contact a personal digital assistant personal organiser to the laptop to exchange information. other interesting thing to note in this figure is that you can also use a single connection to the internet without having to have a direct cable connection to the modem or broadband connection.2.7 ScatternetsA device can be master of only one piconet. The device can, at the same time, also be a slave in another pic onet that is within range. A slave can also participate in two different piconets that are within its range. However, because the master device determines the hoping pattern used for a piconet, a device cannot be a master of more than one piconet. An example of a simple scatternet is shown in figure.In this figure, a laptop computer communicates with devices in both piconets. Note that the laptop is a slave in both piconets. It is possible, however, for the laptop to be a master in one piconet and a slave in another (as shown in the figure). When a device is genus Phallus of two piconets it keeps track of both frequency-hoping patterns and occasionally listens in on the correct frequency on each of the two piconerts so that it can go forward in touch with both piconets. A master device transmits a packet to its slaves occasionally to maintain the link, base band on negotiations between the master and its slave devices. Thus, a device that is a member of two piconets must listen fo r these transmissions (or make them if its the master in one piconet) within the time frame negotiated for each of the piconets of which it is member. The above explanation can be understand better with the below figure.Bluetooth transmitter consists of CODE MAPINGPFDBALUNAMPLIFIERSAMPLIFIER DETECTOR wake up PUMPT/R SWITCHPFD/CPCAP ARRAY3. Advantages and Disadvantages of BluetoothThe main advantage of Bluetooth is its compact form and portability. This technology can be make bum and can be integrated to micro-levels easily. Bluetooth signals are very unsusceptible to weather conditions and can often operate where other technologies may fail. contempt its short range the technology can be very legal and cheap where long distance coverage is not required. In newfangled hardware Bluetooth is being used widely. Almost all platforms are benefiting from its cheap production such as cell phones, gaming consoles, computer computer peripheral devices etc. Even computers can achieve LA N connectivity using Bluetooth. Another great feature of this technology is its less power consumption.The only discriminate of this technology is perhaps its short range and limited connections i.e. only up to eight devices can connect be connected simultaneously.4. ConclusionThe main aims of Bluetooth are to provide universal radio interference for ad hoc wireless connectivity at low cost, delivering modest speed (1-3Mbps) short range (1-100M) and low power consumption.Bluetooth is a very powerful tool. This technology has proven to be very cost effective and powerful. Over the years we have seen rapid enhancements in this technology. This technology has replaced the previously famous infrared technology which was mutually beneficial on line of sight connections. Through Bluetooth one can achieve an effective data transfer rate and easier connectivity regardless the weather conditions.References1. Kumar Bala C, Klien Paul, Thomson Tin, Thomson J. timothy Bluetooth application p rogramming with Java applications2. Iniewski Krzysztof piano tuner Technologies Circuit, establishments, Devices3. Miller Stewart S. WiFi security measure4. Patrick David, Morrow Robert Wireless network Co-Existence5. Ganguly Madushree Getting Started With Bluetooth6. Kelly Jod, Schaub Keith B. Production Testing of RF and System-on-Chip Devices for Wireless7. Nicholas Randall K., Lekkas Panos C. Wireless Security Models, Threats and Solution8. Golrnie Nada Coexistance in Wireless Networks Challenges and System Solutions9. Prabhu C. S. R., Reddi Prathap A. Bluetooth Technology and its Applications with Java and J2ME10. Zolfaghari Ali Raza Low-Power CMOS Design for Wireless Transceivers11. Morrow Robert, Laroka James Demystified Operation and habit12. Muller Scott Upgrading and Repairing Networks13. Hill Goff The Cable and Telecommunication Professional References PSTN, IP