Arne Fitzenreiter

IPFire 2.13 Beta 2 - Part 3 Wireless LAN
by Arne Fitzenreiter, January 21, 2013

Today, we are releasing the second beta version of IPFire 2.13.

The changes are as follows:

A full list of all commit can be found in our git repository.

You may either download this version right here or update your existing installation.

Please keep in mind, that this is a development version and is not recommended for use in a productive environment. We recommend that you set up your own testing lab and we appreciate bug reports.

Part 3 – New Wireless LAN features

Wireless networks are an essential part of our lives. The only problem with them: They are slow. The media presents us devices that are capable of transfering “up to 300 MBit/s”. We all know, that this is a lie, because at least half of the bandwidth is used by CSMA/CA, the protocol that should avoid packet collisions and hence we cannot use it to transfer our valuable data.

If that is not already bad enough, the air is crowded with wireless networks. All of them are sending out their beacon frames – every 100ms. That makes them to announce their wireless network ten times in a second with an “I am here” message, which again reduces our usable amount of the bandwidth. Imagine a building with a bunch of companies all having their own wireless networks which them start to interfere with each other, because they send out their packets on the same frequency? The result is a noise level in the air which is as loud as a busy Starbucks store.

Some people start using bigger antennas. But imagine that suddenly everybody in that Starbucks store starts shouting. Nobody would get a word. At the same time, the big antenna collects more weak signals from far away i.e. picks up more noise. That’s not what you want and does not fix the problem – at all.

But what can we do about it? People are getting more and more technical gadgets and other technologies are crowding the 2.4 GHz band as well (microwave ovens, Bluetooth and so on…). Wifi has got a technique, that stops stations from sending any data if the channel is busy. That means if you are running your microwave oven, the bandwidth of your wireless network decreases massively.

802.11a/n and the 5 GHz band

In the 802.11a and 802.11n specifications, there is a second frequency band at about 5 GHz. It is also free to use and a lot of wireless hardware is able to use it. Of course it is not as simple as that: Setting up a new access point that uses a higher channel and everything in the house connects to it and you are done. It is a problem for some people that the range of a 5 GHz network is nearly half of the range of a 2.4 GHz network. But to highlight the good side of that medal, your neighbours’ wifi networks won’t interfere with yours any more. That leaves you with a lot more bandwith if you can afford to have a smaller range – most places do.

On the other side of the medal: A lot of devices do not support the 5 GHz band. Partly because it consumes more power to send and receive data and that’s a problem on mobile devices. Others don’t support it because the manufacturers wanted to save some money and used a cheaper wifi module. If you have such a device on your network you are screwed. If you don’t have got one, your are lucky to at least check out the difference.

All you need is a wifi adapter in your IPFire box that supports the 5 GHz frequency band and is supported by the Linux kernel drivers. Setting up the access point that up is very easy. After that you can enjoy the comfort and advantages of the 5 GHz frequency band.

Thanks to all of you who helped that this feature could be implemented. If you want to help too, please visit the IPFire wishlist.

Posted: January 21, 2013 • 833 views