Wireless LANs and PANs : Data Communication and Computer Networks Asst. Prof. Chaiporn Jaikaeo, Ph.D. Computer Engineering Department Kasetsart University, Bangkok, Thailand Adapted from lecture slides by Behrouz A. Forouzan © The McGraw-Hill Companies, Inc. All rights reserved Materials taken from lecture slides by Karl and Willig

2 Outline Electromagnetic spectrum and ISM bands Electromagnetic spectrum and ISM bands IEEE (Wi-Fi) IEEE (Wi-Fi) Bluetooth Bluetooth IEEE IEEE

3 Electromagnetic Spectrum Government regulations make specific ranges of the electromagnetic spectrum available for communication Government regulations make specific ranges of the electromagnetic spectrum available for communication A license is required to operate transmission equipment in some parts of the spectrum A license is required to operate transmission equipment in some parts of the spectrum Some parts are unlicensed Some parts are unlicensed RF range

4 ISM Bands Industrial, Scientific, and Medical frequency bands Industrial, Scientific, and Medical frequency bands Can operate without FCC licenses Can operate without FCC licenses Tx output power  1 watt Tx output power  1 watt Eliminate cost and time consuming for licenses Eliminate cost and time consuming for licenses 26 MHz 902 MHz 928 MHz 915 MHz* 100 MHz 2.40 GHz 2.50 GHz 2.45 GHz 150 MHz GHz GHz 5.8 GHz * Region 2 onlyRegion 2

Wireless LANs: IEEE (Wi-Fi)

6 IEEE IEEE Standard for Wireless LANs IEEE Standard for Wireless LANs Covers both physical and data link layers Covers both physical and data link layers Wi-Fi Access pointsWi-Fi Router

7 WLAN Architectures Basic Service Set (BSS) Basic Service Set (BSS) Extended Service Set (ESS) Extended Service Set (ESS)

8 Basic Service Set (BSS) (Ad hoc mode)(Infrastructure mode)

9 Extended Service Set (ESS)

10 IEEE Physical Layer IEEE MAC a802.11b802.11g802.11n 6-54 Mbps 5 GHz OFDM 1-11 Mbps 2.4 GHz DSSS 6-54 Mbps 2.4 GHz OFDM DSSS Mbps 2.4, 5 GHz OFDM Mbps 2.4 GHz FHSS DSSS IR

11 IEEE b/g Channels See

12 IEEE MAC Layer PCF – Point Coordination Function (controlled access) DCF – Distributed Coordination Function (random access)

13 CSMA/CA Used by Basic CSMA/CA not enough Basic CSMA/CA not enough "Hidden Terminal Problem" "Hidden Terminal Problem" ABC

14 CSMA/CA With RTS/CTS RTS CTS Data ACK ABCD NAV  Network Allocation Vector (Virtual Carrier Sensing)

15 IEEE and Wi-Fi IEEE provides most of the standards IEEE provides most of the standards A group of vendors who build wireless equipment formed the Wi-Fi Alliance A group of vendors who build wireless equipment formed the Wi-Fi Alliance A non-profit organization that tests and certifies wireless equipment using the standards A non-profit organization that tests and certifies wireless equipment using the standards

Wireless PANs: Bluetooth

17 Bluetooth Standard Wireless Personal Area Network technology Wireless Personal Area Network technology Designed for connecting devices with different functionalities: Designed for connecting devices with different functionalities: Telephone, mouse, keyboard, camera, etc. Telephone, mouse, keyboard, camera, etc. Standard  IEEE Standard  IEEE

18 Bluetooth Piconet

19 Bluetooth Scatternet

20 Bluetooth Layers

21 Bluetooth Communication Single slave Single slave

22 Bluetooth Communication Multiple slaves Multiple slaves

Low-Rate Wireless PANs: IEEE

24 IEEE IEEE standard for Low-Rate WPAN (LR-WPAN) applications IEEE standard for Low-Rate WPAN (LR-WPAN) applications Low-to-medium bit rates Low-to-medium bit rates Moderate delays without too strict requirements Moderate delays without too strict requirements Low cost, low energy consumption Low cost, low energy consumption Applications Applications Home automation and security systems Home automation and security systems Smart metering Smart metering Wireless data collection Wireless data collection

25 868MHz (20 kbps) 2.4 GHz MHz Channel 0 Channels 1-10 Channels GHz 928 MHz902 MHz 5 MHz 2 MHz 2.4 GHz PHY IEEE Physical Operating frequency bands Operating frequency bands 915 MHz (40 kbps) 2.4 GHz (250 kbps)

26 IEEE MAC Single channel at any one time Single channel at any one time Combines contention-based and schedule- based schemes Combines contention-based and schedule- based schemes Asymmetric: nodes can assume different roles Asymmetric: nodes can assume different roles

27 IEEE Devices Full function device (FFD) Full function device (FFD) Any topology Any topology Network coordinator capable Network coordinator capable Talks to any other device Talks to any other device Reduced function device (RFD) Reduced function device (RFD) Limited to star topology Limited to star topology Cannot become a network coordinator Cannot become a network coordinator Talks only to a network coordinator Talks only to a network coordinator Very simple implementation Very simple implementation

28 IEEE Topologies