WifiNigel

I recently had an interesting customer WiFi performance issue to investigate which turned out to be a whole host of issues on the 2.4GHz band that he was using for his WiFi network. His issues were solved by moving his clients (iPads in this case) across to the 5GHz band, which instantly gave much higher throughput and reliability. However, when he was testing his much-improved network by doing some throughput testing with an iperf server, I noted a sound of disappointment in his voice when he said that he couldn't get a throughput greater than 35Mbps on his iPad.I told him that this was, in  fact, as good as it was ever going to get when using an iPad, even with high performance 802.11n access points. I thought it might be useful to have a look at what realistic throughput figures might be for an iPad on a WiFi network when using 802.11n access points, and why we hit much lower throughput figures than we might expect from the AP manufacturer data sheets. I set up my home lab

Apologies for the appalling title of this blog post, but hey, you're here! :) In this post I talk about my purchase of a Raspberry Pi (by devious means) and how I set it up as an iPerf server. I have recently been reading lots about the Raspberry Pi mini/micro/teeny-weeny ( I don't know what the correct term is...) single board computer, which has been created by the Raspberry Pi Foundation in a attempt to promote the teaching of basic computer science in schools (according to Wikipedia ). I've been itching to get my hands on one for a while and finally came up with a great excuse to buy one and have a play with it. They're incredibly cheap (around £30 for the basic computer board), so I concocted a flimsy excuse about buying one to teach my son about computing. After letting him play with it (and get bored) for about 30 minutes, I quickly slipped in to my home lab where I will no doubt continue to 'evaluate' it. The Pi is supplied with a flavour of Debia

I was inspired to try a bit of experimentation following Keith Parsons' recent WiFi stress testing sessions, where he conducted testing on a number of vendor APs to observe at what point they collapsed in to a heap  due to traffic throughput. I can't carry out anything as grand or detailed as Keith (I don't have his knowledege, brains or resources!), but I thought it might be fun to test some de-facto rules around the use of the 2.4GHz band for WiFi. In summary, due to the bandwidth requirements of WiFi equipment, it recommended that the spacing of at least 22MHz is allowed between the channels being used in the 2.4GHz band. This is required for the bandwidth requirements of the older DSSS modulation scheme. The newer OFDM modulation technique requires only 20MHz of space, but for reasons of backward compatibility, the 22MHz rule persists. The band itself is sliced up in to 11, 13 or 14 channels depending where you are in the world. Each channel is 5MHz in width, as