1. Wireless Networking 802.11b

2. Wireless Networking 802.11b 802.11 1-2 Mbps Adopted June 1997

3. Wireless Networking 802.11b September 1999 802.11b adopted 11Mbps Actual throughput under 5.5 Mbps Also called Wi-Fi Uses CSMA/CA

4. Wireless Networking 802.11b Here are some illustrations of how a wireless network is put together http://www.homenethelp.com/802.11b/ index.asphttp://www.homenethelp.com/802.11b/ index.asp

5. Wireless Networking 802.11b CSMA/CA mostly copies 802.3’s CSMA/CD Wireless can’t use collision detect because it can’t sense and transmit at the same time Uses a backoff timer and active handshaking- RTS/CTS Addresses “hidden node” problem

6. Wireless Networking 802.11b

8. Uses direct sequence spread spectrum in the 2.4 GHz band Go to http://www.wireless- nets.com/articles/whitepaper_spread.htm for a clearer understanding of DSSS and a comparison with frequency hopping spread spectrumhttp://www.wireless- nets.com/articles/whitepaper_spread.htm

9. Wireless Networking 802.11b Eleven 30Mhz overlapping channels available in the US. Europe uses channels 1-13 Japan uses channel 14 only Is compatible with 802.11 Falls back to lower speed with distance and noise

10. Wireless Networking 802.11b 5 MHz between channels 30 MHz bandwidth channels Spread spectrum allows overlap, but causes problems Compare with usual guard band

11. Wireless Networking 802.11b Channel 1 starts at 2.412 GHz and channels progress at 5MHz intervals. Ch2= 2.417GHz, Ch3=2.422GHz, etc. If you want no overlap, use Channels 1, 6, and 11

12. Wireless Networking 802.11b Channel Distribution

13. Wireless Networking 802.11b 802.11 2 Mbps 802.11a54 Mbps at 5 GHz (not WiFi) 802.11b11 Mbps at 2.4 GHz (also WiFi) 802.11e adds QoS to a and b 802.11g54 Mps at 2.4 GHz (meets WiFi) 802.11h is a European standard like g 802.11i provides added security options

14. Wireless Networking 802.11b Hubs called Access Points They function as bridges, isolating the MAC layer functions NICs have radios and antennas APs are physically wired to the rest of the network

15. Wireless Networking 802.11b NIC

16. Wireless Networking 802.11b Range is 200 to 500 feet in an open office (claimed), 100 feet or less in closed offices Designed to be used with laptops Adapters for desktop computers were largely ineffective because of shielding problems Site surveys determine antenna placement http://www.wi- fiplanet.com/tutorials/article.php/2243911 http://www.wi- fiplanet.com/tutorials/article.php/2243911

17. Wireless Networking 802.11b Wireless networks are designed by doing a Site Survey to measure signal strength. There are built-in tools with every AP, but a Spectrum Analyzer does a much better job Spectrum Analyzers can display all of the frequencies within the range you are going to use, but they’re several thousand dollars.

18. Wireless Networking 802.11b Troubleshooting wireless networks can be difficult. Use network analyzers designed specifically for Wireless networks. Sniffer Wireless by Network Associates $10,000 Airopeek by Wildpackets, $3500

19. Wireless Networking 802.11b WEP is the security method (Wired Equivalent Privacy) Uses encryption. Weak, and causes a big impact on network speed Security is a major concern Biggest problem, most don’t implement any security at all

20. Wireless Networking 802.11b Here’s a little article about how to use WEP and the alternatives. http://www.80211- planet.com/tutorials/article.php/2106281http://www.80211- planet.com/tutorials/article.php/2106281 Here’s an article about the shortcomings of WEP. http://www.isaac.cs.berkeley.edu/isaac/wep -faq.html http://www.isaac.cs.berkeley.edu/isaac/wep -faq.html

21. Wireless Networking 802.11 802.11a runs at 5 GHz range Not compatible with 802.11b 54 Mbps, but very short range Requires lots of power Not often implemented

22. Wireless Networking 802.11 802.11a has not gained popularity because it’s expensive and incompatible with 802.11b. It also consumes a lot of power. However, at 54Mbps it’s fast.

23. Wireless Networking 802.11 802.11g runs at 54 Mbps 2.4 GHz band Became a standard June 2003, shipping since 2002 http://zdnet.com.com/2100-1105- 957229.htmlhttp://zdnet.com.com/2100-1105- 957229.html Compatible with 802.11b Also short range

24. Wireless Networking 802.11 802.11g is slower than b in some tests Adding an 802.11b device to an 802.11g network slows the entire network. For commercial applications, you may want to wait for the hardware to stabilize before adoption.

25. Wireless Networking 802.11 Prices, as of Fall 2003 802.11b bridges cost about $70, cards $30 802.11b+ (non standard, 22Mbps, TI) cost about $100, cards $40 802.11G bridges cost about $140, cards $90 Dual band 802.11a and g are ~$300

26. Wireless Networking 802.11b Personal Telco Communities of Portland http://www.personaltelco.net/index.cgi/Portl andWirelessCommunitieshttp://www.personaltelco.net/index.cgi/Portl andWirelessCommunities Privately funded, all volunteer Here is a national list of wireless “hot spots” http://www.wififreespot.com/http://www.wififreespot.com/

27. Wireless Networking 802.11b Voice VoIP is moving ahead in the workplace, but the proliferation of 802.11 may begin to cut into the cellular telephone market as well. http://www.internetnews.com/wireless/articl e.php/10799_2197391http://www.internetnews.com/wireless/articl e.php/10799_2197391

28. Wireless Networking 802.11b London is planning to use 802.11 for their security cameras and for public workers like parking meter enforcers. Cisco is in this picture too. http://www.theregister.co.uk/content/59/304 04.htmlhttp://www.theregister.co.uk/content/59/304 04.html

29. Wireless Networking 802.11b Commercial wireless hot spots are becoming more common, but profit seems to be elusive.

30. Directional Antenna 24 dB 8 degree

31. Directional Antenna 12dB Gain

32. Wireless Networking 802.11b Overlapping WLANs is becoming a problem. Service Set Identifiers, (SSID), are unique 32 character network identifiers that help make sure the proper network gets the data. The SSID is attached as a header to all packets. It is transmitted in the clear, so it doesn’t add to security. Also called the Network Name

33. Wireless Networking 802.11b To stay current in this emerging technology, go to the WiFi Networking News at http://wifinetnews.com/ http://wifinetnews.com/ Or 802.11 Planet at http://www.80211-planet.com/http://www.80211-planet.com/ Check out a tutorial on 802.16. It has a range of 30 miles and a data rate of 70 Mbps http://networking.earthweb.com/netsp/article.php/ 3065261http://networking.earthweb.com/netsp/article.php/ 3065261

34. Wireless Networking Alternatives Check out a tutorial on 802.16 as an alternative to last mile coverage. It has a range of 30 miles and a data rate of 70 Mbps. It operates in from 10-66 GHz range. http://networking.earthweb.com/netsp/articl e.php/3065261http://networking.earthweb.com/netsp/articl e.php/3065261

35. Wireless Networking 802.11b A great source for information about 802.11 is http://www.netstumbler.com/http://www.netstumbler.com/

36. Wireless Networking Alternatives CDMA2000 is a 3G wireless phone alternative. It operates at 144Kbps and is backward compatible with standard CDMA cell phones. Operates in the 800 MHz band Qualcomm chipset http://www.ericsson.com/cdmasystems/3gc dma2000.shtmlhttp://www.ericsson.com/cdmasystems/3gc dma2000.shtml

37. Wireless Networking Alternatives Bluetooth was designed as an inexpensive, point- to-point wireless connectivity solution designed for low speed, very short range (30’) communication. It uses frequency hopping spread spectrum at low power in the unlicensed 2.4 GHz range. A comparison of 802.11b and Bluetooth is at: http://www.wi- fiplanet.com/tutorials/article.php/2210461http://www.wi- fiplanet.com/tutorials/article.php/2210461