Chapter 5
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  • 1. Wireless CommunicationsLow Rate Wireless Personal Area Networks
  • 2. Objectives• Describe a wireless personal area network (WPAN)• List the different WPAN standards and their applications• Explain how IrDA, Bluetooth, and ZigBee work• Describe the security features of low-rate WPAN technology 2
  • 3. What is a WPAN?• Wireless personal area network (WPAN) – Group of technologies that are designed for short- range communications – Eliminates the need for wires or cables to interconnect multiple devices• Applications for WPAN technology include: – Synchronizing PDAs, cellular, and Smartphones – Home control systems (smarthome) – Cordless telephones – Portable device data exchange 3
  • 4. What is a WPAN? (continued)• Applications for WPAN technology include (continued): – Industrial control systems – Location — smart tags used to locate people at home or at the office – Security systems – Interactive toys – Inventory tracking• Advantages – WPAN devices use very little power – Short range helps maintain security and privacy 4
  • 5. Infrared WPANs (IrDA)• Most common infrared connection today – Based on the IrDA specifications• IrDA specifications – Define both physical devices and network protocols• IrDA devices’ characteristics – Provide walk-up connectivity – Provide a point-to-point method of data transfer • Between only two devices at a time 5
  • 6. Infrared WPANs (IrDA) (continued) 6
  • 7. Infrared WPANs (IrDA) (continued)• Serial Infrared (Version 1.0) – Designed to work like the standard serial port on a PC – Uses a UART (Universal Asynchronous Receiver/Transmitter) • Microchip that also controls a computer’s serial interface• Fast Infrared (FIR) (Version 1.1) – Extends the data rate to 4 Mbps – When two IrDA devices first communicate • They both transmit using SIR • Then they shift to FIR speed 7
  • 8. RF WPANs• Offer functionality beyond that of IR devices• Include – Bluetooth – 802.15.4 (ZigBee) 8
  • 9. IEEE 802.15.1 and Bluetooth• Industry specification – Bluetooth Special Interest Group (SIG)• Defines small-form-factor, low-cost wireless radio communications• IEEE licensed this wireless technology – To adapt and copy a portion of the specification as the base material for 802.15.1• 802.15.1 standard – Approved in March 2, 2002 – Fully compatible with Bluetooth version 1.1 9
  • 10. Bluetooth Protocol Stack• Bluetooth RF layer – Defines how the basic hardware that controls the radio transmissions functions – Data bits (0 and 1) are converted into radio signals and transmitted• Radio module – A single radio transmitter/receiver (transceiver) – Only hardware required for Bluetooth to function – Bluetooth can transmit at a speed of up to 1 Mbps – Bluetooth version 2.0 transmits at 2 or 3 Mbps 10
  • 11. Bluetooth Protocol Stack (continued) 11
  • 12. Bluetooth Protocol Stack (continued) 12
  • 13. Bluetooth Protocol Stack (continued) 13
  • 14. Bluetooth Protocol Stack (continued)• Network topologies (continued) – Scatternet • Group of piconets in which connections exist between different piconets – To communicate in each different piconet • Device must use the master device address and clock of that specific piconet – Bluetooth device can be a slave in several piconets • But can be a master in only one piconet – A master and slave can switch roles in a piconet 14
  • 15. Bluetooth Link Manager Layer (continued)• Link between Bluetooth devices (continued) – Bluetooth power usage (continued) • Power-saving modes – Active – Sniff – Hold – Park 15
  • 16. Low Rate WPAN Security• Security should be of little concern with WPANs• One of the most serious concerns is social engineering• Designing security in WPANs – Much more difficult task than in other networking technologies• Public key infrastructure (PKI) – Unique security code, or key, provided by a certificate authority• Certificate authority – Private company that verifies the authenticity of users 16
  • 17. Security in Infrared WPANs• Limited to the line-of-sight characteristic of this type of connection• IrDA specification makes no provision for encrypting data or protecting the connection – Users may encrypt a file before exchanging it• IrDA devices support open access – So that anyone can transmit files without first notifying the device’s owner• Open access can be a major security concern• Bluetooth provides security at the LMP layer – Using authentication• Authentication is based on identifying the device itself• Authentication scheme is a challenge-response strategy• Encryption is the process of encoding communications – And ensures that the transmissions cannot be easily intercepted and decoded 17
  • 18. Summary• The most common infrared connection today is based on the IrDA standard – IrDA devices cannot send and receive at the same time – IrDA is easy to use• Bluetooth is a wireless technology that uses short- range radio frequency (RF) transmissions – Supported by over 2,500 hardware and software vendors 18