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Showing posts with the label 802.11n

Noise Floor Penalty of Wider Channels in Wi-Fi Networks

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I’ve been told a number of times that although wider channels in a Wi-Fi network generally provide a higher connection speed (and hopefully a higher throughout), it comes at the cost of increasing the perceived noise floor of the client device. I thought it would be interesting to test this out for myself.With the advent of 802.11n, it became possible to bond together the 20MHz wide channels of earlier standards in to 40MHz channels (though in reality, this was only practically feasible on the 5GHz band). Several years later, 802.11ac enabled us to bond together even larger chunks of contiguous channels and achieve 80MHz and 160MHz wide channels on the 5GHz band. Though 80MHz channels are not feasible in many environments and 160MHz is limited to very niche scenarios, they nonetheless are options.Theoretically, each time we double our channel width, we are going to double our connection speed and our throughput (there are some protocol efficiencies achieved which mean we may slightly …

How Fast Is My Wi-Fi Client?

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In the Wi-Fi For Beginners podcast, I've spent a lot of time talking about WLAN clients. Understanding their characteristics, capabilities and behavior is crucial when designing and deploying a wireless LAN. Without understanding the clients on your network, you will not be able to anticipate their demands on your WLAN infrastructure and the level of performance that you will be able to realistically be able to provide to end users.

The discussion about WLAN clients is fairly extensive and spans a number of episodes as this is such an important topic. In the podcast I highlight the importance of understanding the capabilities of the clients that connect to a WLAN. Just because you buy yourself a nice new shiny smartphone that (you hope) supports 802.11ac, doesn't mean you are going to get 1.3Gbps of throughput when you hook it up to your Wi-Fi network. Unless you understand its capabilities in terms of 802.11 amendment support, number of streams available etc., then you can ne…

The Missing Channels on 5GHz in the UK : 120, 124, 128

In my recent article : 'WiFi Channels On The 5GHz Band In The UK', I noted that although the 5GHz channels 120, 124 and 128 are unlicensed channels available for use by WiFi equipment in the UK, it appears that a few major WiFi equipment manufacturers do not allow their use (in the UK or EU).

I spoke with a major vendor representative today who advised me that the 3 channels are available for use, but that an update to the ETSI standard 301 893 v1.5.1 introduced some detection techniques for various military equipment used in the EU. However, many access points that were already manufactured (or using chip-sets that had already been manufactured) did not support the granularity of detection that is required for this equipment. So, it was decided to simply disable support for the affected channels.

Apparently, later APs which use an updated chip-set will not be subject to the same limitations (once a few firmware updates are sorted out).

I had a poke about in the standard to se…

Which 5GHz Channels Does My Device Support?

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I've been on a bit of a 5GHz quest recently, trying to get to grips with all of the nuances of supporting WiFi devices on this rather (in my mind) troubling band.

Until fairly recently, it seems that the default band of choice for many WiFi devices has been 2.4GHz (802.11g/n). But as the whole 'bring your own device' area has exploded, networks require more high-density deployments, 802.11ac is on the horizon and consumer grade devices are starting to support 5GHz in increasing numbers, it looks like 5GHz is going to transition to being the band of choice over the next year or two.

However, there seem to be a number of considerations that need to be taken in to account when delving in to the 5GHz 'wonderland'. There are far more non-overlapping channels available (19 in the UK) compared to 2.4GHz (generally 3 channels), which is going to potentially deliver much better performance gains (with the mitigation of co-channel interference, lower noise floor etc.). Howev…