Can a Wifi network really be better than a wired one? Clearly there are situations where wireless links have to be used - in warehouses, for instance, one of the applications for which Wifi was originally conceived. Clearly, too, Wifi speeds can peak faster than those on an wired 100Mbit/sec lan.

But peaks speeds are not the full picture: what matters is the speeds users can expect to get reliably. On a wired local network you have contention only between users; Wifi, in cities at least, almost invariably introduces a second layer of contention in the use of the airwaves by neighbouring networks.

Proxim says its new AP-8000 access point uses dynamic frequency control to minimise this airwave contention; this means it checks out what frequencies are being used locally and avoids them. But, as we report today, it also aggregates two 40MHz channels - potentially halving the number available in the relatively uncongested 5GHz band.

In large campus sites, where there are no neighbours to shout down and a network manager can carefully position and configure access points for optimal use of the spectrum, this may not matter.  

Proxim says it deployed five of its new access points at Microsoft's TechEd conference in Barcelona, each serving an average 70 users with a data rate peaking at 175Mbits/sec. Robb Henshaw, senior manager of corporate communications, agreed in an email that sporadic access could be a problem in such circumstances. 

But he went on: "Network planning took care of possible interference by using channels appropriately. Since the throughput in a network is an aggregate of all the clients, the highest throughput level ... was not sustainable for long period[s]. But our observation was that network was very stable even with more than 70 clients connected while running the throughput tests.      

He agreed that increasing range increases the chance of airwave contention but he argued that it also meant fewer access points were required to cover a given area, reducing the chances of contention.

So what is going to happen if everyone starts doubling up 40MHz channels as they did with 20MHz ones? It would leave just six non-overlapping channels at 5GHz, with the range doubling not only horizontally but also in direction of any floors below and above you. And you would have no control over how many access points are within range, or what frequencies they are using.

And these access points do not appear to have transmit power control, so they are shouting all the time. Add to that the fact that network traffic is certain to increase with the increasing use of multimedia, including high-definition video.

These Proxim boxes are meant for enterprise use where neighbours are not always going to be an issue. But enterprise features tend to migrate to consumer products, especially when they allow manufacturers to put a bigger number (320MBit Turbo!) on the box. .

Then there is the general issue of radio pollution. Even if Wifi can replace a wired network, is it wise to encourage the practice? Is it not better as a matter of principle to keep the noise down by using radio only where necessary ? Wifi was designed as an edge technology, complementing a wired network, and it should stay that way.