CWNA Guide to Wireless LANs, Second Edition

1. CWNA Guide to Wireless LANs, Second Edition Chapter Twelve Personal, Metropolitan, and Wide Area Wireless Networks

2. Objectives • Define a wireless personal area network • List the technologies of a wireless metropolitan area network • Describe the features of a wireless wide area network • Discuss the future of wireless networking CWNA Guide to Wireless LANs, Second Edition

3. Wireless Personal Area Networks • Wireless networks classified into four broad categories: • Wireless personal area network (WPAN): Hand-held and portable devices; slow to moderate transmission speeds • Wireless local area network (WLAN): i.e., IEEE 802.11a/b/g • Wireless metropolitan area network (WMAN): Range up to 50 kilometers • Wireless wide area network (WWAN): Connects networks in different geographical areas CWNA Guide to Wireless LANs, Second Edition

4. Wireless Personal Area Networks (continued) Figure 12-1: Wireless network distances CWNA Guide to Wireless LANs, Second Edition

5. Wireless Personal Area Networks (continued) Figure 12-2: Point-to-point transmission CWNA Guide to Wireless LANs, Second Edition

6. Wireless Personal Area Networks (continued) Figure 12-3: Point-to-multipoint transmission CWNA Guide to Wireless LANs, Second Edition

7. Wireless Personal Area Networks (continued) • WPANs encompass technology designed for portable devices • PDAs, cell phones, tablet or laptop computers • Low transmission speeds • Three main categories: • IEEE 802.15 standards • Radio frequency ID (RFID) • IrDA CWNA Guide to Wireless LANs, Second Edition

8. Bluetooth • Although Bluetooth is one of the most widely anticipated wireless technology of past ten years, its future is uncertain • It holds great promise for sending and receiving radio frequency signals between PDAs, cell phones, and notebook computers, but its acceptance has been much slower than predicted because of technological and economic considerations CWNA Guide to Wireless LANs, Second Edition

9. What is Bluetooth? • Wireless technology using short-range radio frequency (RF) transmissions • Designed by Ericsson in 1994 for cellular phones • Allows users to connect a wide range of computing and telecommunications devices without cables • Provides on-the-fly connections between devices CWNA Guide to Wireless LANs, Second Edition

10. How Bluetooth Is Used • Low-powered wireless data and voice transmission technology • Smart technology that can recognize another Bluetooth device within range and automatically synchronize • Examples include cellular telephones that automatically dial Internet Service Provider (ISP), and download email to notebook computer in briefcase or send audible e-mail message • See Figure 5-1 CWNA Guide to Wireless LANs, Second Edition

11. Bluetooth Scenario CWNA Guide to Wireless LANs, Second Edition

12. Bluetooth vs. IrDA • Each with pluses and minuses, these two technologies complement one another more than compete with each other • IRDA has limited range and narrow angle • See Figure 5-2 • Bluetooth is omnidirectional and can synchronize while user is mobile • See Figure 5-3 CWNA Guide to Wireless LANs, Second Edition

13. IrDA Transmission CWNA Guide to Wireless LANs, Second Edition

14. Bluetooth Transmission CWNA Guide to Wireless LANs, Second Edition

15. Bluetooth SIG • Over 2500 hardware and software vendors make up Bluetooth Special Interest Group (SIG) • Develops technical specifications allowing interoperability across devices from different vendors • Administers test facilities to ensure devices conform to standards • Established 11 working subgroups • Working with IEEE to make Bluetooth technology an IEEE standard CWNA Guide to Wireless LANs, Second Edition

16. How Bluetooth Works • Robust radio frequency technology • Overall Bluetooth protocol stack • Lower levels use hardware • Upper levels use software • See Figure 5-4 • Specific layers have different functions CWNA Guide to Wireless LANs, Second Edition

17. Bluetooth Protocol Stack CWNA Guide to Wireless LANs, Second Edition

18. RF Layer • Lowest level of Bluetooth protocol stack • Defines basic hardware that controls radio transmissions functions • Converts data bits into radio signals that are transmitted and received CWNA Guide to Wireless LANs, Second Edition

19. Radio Module • Only hardware required is single tiny chip called Bluetooth radio module • See Figure 5-5 • Added during manufacturing process • Device ready to work right out of the box • Characteristics of radio module • Performs all functions by single chip • As generic as possible • Low-cost • Minimum of supporting off-chip components CWNA Guide to Wireless LANs, Second Edition

20. Bluetooth Transceiver CWNA Guide to Wireless LANs, Second Edition

21. Functional Block Design of Bluetooth Transceiver • Figure 5-6 shows functional block design of Bluetooth transceiver • Can interface through various connections • UART (Universal Asynchronous Receiver/ Transmitter) serial port connection • USB (Universal Serial Bus) connection • PCI (Peripheral Component Interface) connection CWNA Guide to Wireless LANs, Second Edition

22. Functional Block Diagram of a Bluetooth Transceiver CWNA Guide to Wireless LANs, Second Edition

23. Bluetooth Speed • Version 1.1 transmits at speed of 1 Mbps • Next generation should send and receive at 2 Mbps • See Table 5-1 CWNA Guide to Wireless LANs, Second Edition

24. Connection Speeds CWNA Guide to Wireless LANs, Second Edition

25. Power Classes • Three Bluetooth power classes • Divisions based on power level measured in milliwatts and maximum distance • See Table 5-2 • Most Bluetooth devices are Power Class 2 with a maximum distance of 33 feet or 10 meters CWNA Guide to Wireless LANs, Second Edition

26. Power Classes CWNA Guide to Wireless LANs, Second Edition

27. Bluetooth Power Consumption • Since most bluetooth devices are mobile and use battery power, it is essential to conserve power • Bluetooth power consumption measured in milliamps • For data transmission, devices use only 6 milliamps; batteries last for 120 hours • For voice transmission, devices use only 10 milliamps; batteries last for 75 hours • During standby, devices use .3 milliamps; batteries last for 3 months CWNA Guide to Wireless LANs, Second Edition

28. Modulation Technique • RF layer defines modulation technique • Bluetooth uses two-level Gaussian frequency shift keying (2-GFSK), a variation of frequency shift keying (FSK) • Two different frequencies indicate whether a 1 or a 0 is being transmitted • Amount of frequency variation, called modulation index, is between 280 KHz and 350 KHz • Frequency decreases to represent a 0 andincreases to represent a 1 • Figure 5-7 shows a 2-GFSK sine wave CWNA Guide to Wireless LANs, Second Edition

29. 2-GFSK CWNA Guide to Wireless LANs, Second Edition

30. Baseband Layer • Manages physical channels and links • Handles packets • Does paging and inquiry to access and inquire about Bluetooth devices in area CWNA Guide to Wireless LANs, Second Edition

31. Radio Frequency • Bluetooth operates in 2.4 GHz Industrial, Scientific, and Medical (ISM) band • Divides ISM band into 79 different frequencies, called channels, spaced 1 MHz apart • Uses frequency hopping spread spectrum (FHSS) • See Figure 5-8 CWNA Guide to Wireless LANs, Second Edition

32. Bluetooth FHSS CWNA Guide to Wireless LANs, Second Edition

33. Solving Incompatibilities • Bluetooth version 1.0b defines a second hop count to avoid 2.4 GHz spectrum that some countries have allocated to other purposes • Divides the frequency into 23 channels, making it incompatible with devices that use 79 channels • Bluetooth SIG negotiated with countries to free up 2.4 GHz spectrum • Devices conforming to current 1.1 version use 79 channels and are completely compatible CWNA Guide to Wireless LANs, Second Edition

34. Conflict with IEEE 802.11b • Bluetooth and IEEE 802.11b WLANs use same frequency • Several possible solutions • Add special software to 802.11 WLAN to cause silence when Bluetooth communication is detected • IEEE working on new standard that lets Bluetooth and 802.11b devices function better in shared space CWNA Guide to Wireless LANs, Second Edition

35. Network Topology • Two types of Bluetooth network topologies • Piconet • Scatternet • Two Bluetooth devices within range automatically connect • One device is the master, controlling all wireless traffic • The other is the slave, taking commands from the master. CWNA Guide to Wireless LANs, Second Edition

36. Piconets • A piconet is one master and at least one slave using the same channel • An active slave is sending transmissions • A passive slave is not actually participating CWNA Guide to Wireless LANs, Second Edition

37. Five Different Modes • Devices in a piconet can be in one of five different modes • Standby—waiting to join a piconet • Inquire—looking for other devices • Page—master device is asking to connect to specified slave • Connected—either active slave or master is connected • Park/Hold—device is part of piconet, but in a low-power state CWNA Guide to Wireless LANs, Second Edition

38. Bluetooth Addresses and Timing • Each Bluetooth device is preconfigured with addresses used when participating in piconet • See Table 5-3 for three significant addresses • Devices in piconet must change frequencies at same time and in same sequence • Master device’s clock determines timing, called phase, in hopping sequence • See Figure 5-10 CWNA Guide to Wireless LANs, Second Edition

39. Piconet Radio Module Addresses CWNA Guide to Wireless LANs, Second Edition

40. Bluetooth Time Slots CWNA Guide to Wireless LANs, Second Edition

41. Connection Process • Bluetooth devices use two-step connection process • Inquiry procedure lets a device discover other devices in range and determine their addresses and clocks, as seen in Figure 5-11 • The first device within range that responds with its own ID and clock receives a confirmation from the inquiring device, as seen in Figure 5-12 CWNA Guide to Wireless LANs, Second Edition

42. Device A Inquiry CWNA Guide to Wireless LANs, Second Edition

43. Response and Confirmation CWNA Guide to Wireless LANs, Second Edition

44. Collision • If two devices simultaneously transmit, a collision occurs and data becomes corrupted • See Figure 5-13 • Each device waits a random number of time slots and starts listening for inquiries again. • Device with shorter time will likely receive inquiry, respond, and receive a confirmation • See Figure 5-14 • Eventually, inquiring device will learn address and timing of all devices in range CWNA Guide to Wireless LANs, Second Edition

45. Collision CWNA Guide to Wireless LANs, Second Edition

46. Response after Random Wait CWNA Guide to Wireless LANs, Second Edition

47. The Paging Procedure • After inquiry is complete, next step is paging procedure which establishes an actual connection • Unit that establishes a connection automatically becomes master of the piconet • See Figure 5-15 CWNA Guide to Wireless LANs, Second Edition

48. Piconet CWNA Guide to Wireless LANs, Second Edition

49. Scatternet • Multiple piconets can cover same area with different master and hop sequences • Device can be a member of two or more overlaying piconets • Group of piconets connected together is called a scatternet, as seen in Figure 5-16 • Communication among piconets occurs using master device address and clock for each piconet • Bluetooth device can be a slave in several piconets, but master in only one CWNA Guide to Wireless LANs, Second Edition

50. Scatternet CWNA Guide to Wireless LANs, Second Edition