OIT Networking & Monitoring Services

OIT Wireless Service and TVWNA Upgraded to 802.11g

OIT Network Systems
March 21 2005
Last Update: July 29 2005

During the Spring and Summer of 2005, OIT Wireless Service and Temporary Visitor Wireless Network Access (TVWNA) was upgraded from 802.11b to 802.11g. The upgrade was completed during July 2005.

802.11b wireless networking provided connection rates up to 11 Mbps. The upgrade to 802.11g increased the maximum connection rate to 54 Mbps.

Although 802.11b clients cannot obtain the higher connection rates supported by 802.11g clients, the older 802.11b clients continue to be supported by the upgraded service.

There is no change necessary at the wireless clients, assuming the wireless client has correctly-functioning hardware. Those wireless clients that support 802.11g will automatically use the higher connection rates.

About Broken 802.11g Clients

Some clients may have wireless hardware that was sold as 802.11g equipment, but does not speak 802.11g correctly. Often, such equipment was sold prior to the 802.11g standard being finalized by the IEEE, and was based on draft versions of the 802.11g standard. 802.11g underwent changes while it was in draft, before it was published as a standard in November 2001.

Such clients may have worked when OIT's services were 802.11b, because those clients didn't try to use their broken 802.11g capabilities. Once OIT upgraded the campus service to support 802.11g, clients that believe they can speak 802.11g automatically try to do so. Those clients with broken 802.11g hardware may find that they are no longer able to use the University's wireless service at all.

Customers with those "broken 802.11g" clients should obtain a fix for their wireless hardware from the vendor that sold the wireless hardware. Typically, the fix is a new version of firmware for your wireless card. Vendors of wireless cards typically make these fixes available for customers to download at no charge.

If it is not possible for you to obtain a fix from your vendor (e.g. you purchased a wireless card from a vendor that has gone out of business), you may be able to work around the problem with the wireless card by reconfiguring your client so it does not try to use 802.11g, but instead restricts itself to only speak 802.11b. Whether this is possible, and how to going about doing so, may vary depending on your client software and hardware.

About Data Rates

Although 802.11b operates at rates up to 11 Mbps, actual throughput is no more than about 6 Mbps.

Although 802.11g operates at rates up to 54 Mbps, actual throughput is no more than about 14 Mbps if there are no 802.11b clients or Wireless Access Points in the same area. If there are any 802.11b clients or Access Points in the same area (even a private Access Point, or a client using another private or OIT Wireless Access Point), actual throughput is expected to be no more than about 8 Mbps. This is expected to the normal situation for many years as there are thousands of 802.11b clients on campus, as well as many private 802.11b Wireless Points; it takes only a single 802.11b device in the area to reduce throughput for nearby 802.11g equipment. This is true even if the 802.11b device is essentially idle (online but moving no data to speak of).

As all wireless devices operating in the same area on the same channel share bandwidth, the bandwidth (e.g. 8 Mbps) is shared among all those clients; each clients receives some smaller fraction of the total.

These figures assume the client is very close to the Wireless Access Point's antenna(s), with no intervening obstacles or other RF interference. Distance, obstructions and interference all reduce performance.

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The Office of Information Technology,
Princeton University