Ad-hoc wireless networks limited to 11mbps!

 
There are basically 2 types of wireless networks. Infrastructure and ad-hoc (also known as peer to peer). Infrastructure is when you have a wireless router and all computers “talk” with the router. Ad-hoc is when one computer talks directly to another.
I was fiddling with some wireless networks, and discovered that indeed the ad-hoc type of wireless networks have a maximum speed of 11 mbps!

from http://labs.pcw.co.uk/2005/03/adhoc-wireless.html

Ad-hoc wireless connections limited to 11mbps

Reader Ian Longdon has drawn our attention to a little-known limitation of ad-hoc (peer-to-peer) wireless networks, typically used between two or more notebooks with Wi-Fi adapters. The IEEE 802.11 standard specifies that performance in ad-hoc mode must achieve 11Mbits/sec, but no more, regardless of whether the adapter is 802.11b or 802.11g. There's no requirement for manufacturers to exceed the 11Mbits/sec specification, and as Ian found with his D-Link cards, some don't.

We asked D-Link and the Wi-Fi Alliance about this problem. D-Link replied:

"Unfortunately we only meet the standard and don't exceed it. D-Link wireless products follow the IEEE 802.11 standards. The 802.11b and 802.11g standards specify that Ad-Hoc mode only needs to support up to 11Mbps. For best results, use an access point or wireless router and set your adapters to Infrastructure (station) mode."

The Wi-Fi Alliance told us that as the standard only specifies a maximum of  11Mbits/sec performance in ad-hoc mode, testing above this speed is not performed as part of the Wi-Fi certification procedure.

While it's arguably unfair to criticise vendors for not exceeding a standard, they certainly don't go out of their way to let users know about this. Some products do appear to connect at higher rates in ad-hoc mode, but it's certainly not advertised and it's very much a 'suck it and see' process to find out. Netgear is one of the few companies with a public statement on the issue.

We'll certainly be keeping an eye out in future when products come through the labs. Thanks again to Ian for informing us about this.

Written by computerboom on July 3rd, 2009 with comments disabled.
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