1. Version 1.1 2006Slide 1 Format of lecture Introduction to Wireless Wireless standards Applications Hardware devices Performance issues Security issues

2. Version 1.1 2006Slide 2 Wireless Technology Wireless and mobile computing are the keywords Very topical/exciting This technology not yet mature Promises that we can improvise our existing networks without having to lay new wires - roving staff will just have to insert a wireless card into their device and join the network Interesting to compare the what the Telco’s are doing with 3G and how this rivals WiFi hotspots

3. Version 1.1 2006Slide 3 Wireless Technology Wireless technology has to compete with digital satellite Cable phone lines (HomePNA) 10Mbps Power line (HomePlug) 14Mbps Wireless broadband technology (WiMax) gives wire-free transmission of two way multimedia Bandwidth is an issue here

4. Version 1.1 2006Slide 4 Wireless Technology What is on the market/coming? Communication cards to allow data from personal digital assistants to be synchronised with desktop PC’s Cards to link laptops and PC’s with Global System for Mobiles(GSM) based phones and local area network devices All the above enables firms to set up wireless networks without having to use Ethernet cable

5. Version 1.1 2006Slide 5 Wireless Protocols Wireless LAN Bluetooth WAP/GPRS/UMTS SWAP - Shared Wireless Access Protocol SWAP 3G - third generation cellular standard

6. Version 1.1 2006Slide 6 Wireless versus Wired networks Using Radio frequency (2.4GHz and 5GHz) Easy to setup a small office or home office (SOHO) Mobility Travel through wall Easy for network reconstruction

7. Version 1.1 2006Slide 7 What is WiFi? Wireless LAN IEEE 802.11x network Promulgated by an association called WiFi Alliance WiFi Alliance certifies all wireless LAN IEEE802.11x based products for interoperability All IEEE802.11x based products that passed the WiFi Alliances are called WiFi Wireless Fidelity

8. Version 1.1 2006Slide 8 WiFi Standards IEEE 802.11a An IEEE standard for a wireless network that operates at 5 GHz with rates up to 54Mbps IEEE 802.11b An IEEE standard for a wireless network that operates at 2.4 GHz with rates up to 11Mbps IEEE 802.11g – referred to as 54g (but don’t confuse that with the 54Mbps!) An IEEE standard for a wireless network that operates at 2.4 GHz with rates up to 54Mbps

9. Version 1.1 2006Slide 9 WiFi Standards WPA (WiFi protected Access) TKIP encryption and protects against unauthorized network access through the use of a pre-shared key (PSK) WMM (WiFi MultiMedia) packet prioritisation that meet IEEE 802.11e quality of service standard. Packets containing time-dependent data such as audio or video to be sent ahead of data that can safely wait a few microseconds

10. Version 1.1 2006Slide 10 WiFi Hardware Access points (APs) PCMCIA cards/ PC cards USB adapters PCI network cards Wireless routers

11. Version 1.1 2006Slide 11 WiFi Applications Retails Warehouses Healthcare Education http://www.wifinetnews.com/ News about wifi and also see if you can find out the hotspot(s) around the Stoke-on-Trent area

12. Version 1.1 2006Slide 12 WiFi topology Ad Hoc Without use of Access Point Peer-to-peer style communication Recommended 3 or less users per channel Infrastructure Communication each other devices by the use of Access Point About 10-30 users per access point

13. Version 1.1 2006Slide 13

14. Version 1.1 2006Slide 14

15. Version 1.1 2006Slide 15

16. Version 1.1 2006Slide 16

17. Version 1.1 2006Slide 17 Ad Hoc vs Infrastructure Ad Hoc can be setup instantly for temporary solution Scalability is limited to Ad Hoc Coverage Reliability Efficiency

18. Version 1.1 2006Slide 18 Wireless LAN

19. Version 1.1 2006Slide 19 Security choices Network security ensures the communications and files are protected How important of the security depend on how you want to use the network. Browsing internet and mp3 streaming may not need a security Internet shopping or purchasing will use SSL security There are several way to protect your data confidentiality while transmitting In WLAN, you can change your SSID, WEP or WPA or latest technology WPA2

20. Version 1.1 2006Slide 20 Wireless surfing Common knowledge that some users use someone else’s network connection to use the Internet “piggybacking” Hi-gain antenna example that I use How do you know someone is using you? If infrastructure – you don’t – would have to look at router logs Ad-hoc – shows in connections window How do they know you are not using them in return?

21. Version 1.1 2006Slide 21 WEP Wired Equivalent Privacy Encrypt data over the radio waves Implemented in MAC layer – NIC encrypt the frame before transmit Using 64bits or 128bits encryption keys Shared secret key You need to provide 40 bits (10 digit Hex) or 104bits (26 digit Hex) 24 bits Initialisation Vector (IV) for generating key sequence

22. Version 1.1 2006Slide 22 Limitation of WEP Share, static keys WEP only encrypt frame within wireless station but not within wired network Limited IV numbers and may increase collision - IV repeats after sending 26GB. Recovery attack - the data can be manipulated after a few hours by tracking repeating IV

23. Version 1.1 2006Slide 23 WPA and WPA v2 WiFi Protected Access Different key for each user 48 bit IV – defeats recovery attack on WEP Use Temporal Key Integrity Protocol (TKIP) which dynamic change keys on transmission More information on http://www.wifi.orghttp://www.wifi.org

24. Version 1.1 2006Slide 24 Summary Security is the main issues in wireless communications Still in the development to increase the privacy Next tutorial you will see wireless security in action