Showing posts with the label 802.11ac

Noise Floor Penalty of Wider Channels in Wi-Fi Networks

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?

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

5GHz in the UK White Paper (Version 2)

[Note: The information in this white paper has been superseded. Check out my updated white paper: ] I decided it was time to update my white paper detailing the use of the 5GHz band here in the UK for wireless LANs. I've tidied a few things up and added some information around 802.11ac channel planning within the constraints of UK 5GHz spectrum. You can download the whitepaper from here: PDF download Google docs Scribd

802.11ac & 5GHz: The Emperors New Clothes? - Part 3

After previously looking at the challenges we may face with 802.11ac due to the restrictions of the 5GHz band (see part 1 and part 2 of this series), in this final installment, I suggest how we may mitigate the challenges we may face, together with a possible (but no doubt controversial) solution. The Solution? I'm not aware of any "magic bullet" to solve all of the challenges outlined in this series of articles (sorry). More spectrum will certainly help things. But, time-scales for the allocation and adoption of new spectrum are not clear at this point in time, though many agencies around the world are considering ways to free up more spectrum to improve WiFi capacity. Though spectrum may become available in relatively short time-frames, there will still, no doubt, be a significant time-lag before this permeates through in to the world of vendor and consumer WiFi products (remember the issues raised around UNII-2e support?)  The best way to mitigate th

802.11ac & 5GHz: The Emperors New Clothes? - Part 2

In part one of this series looking at 802.11ac challenges, we looked at the issues that the use of the 5GHz band brings, particularly around DFS. In this second installment, we look at further challenges to designing and deploying 802.11ac networks. Extended Channel (UNII-2e) Device Support Although we may be located well away from any obvious sources of radar interference, there may be other obstacles to the 5GHz nirvana outlined in the 802.11ac marketing briefs. One ugly fact affecting WiFi networks on the 5GHz band is that not all devices that use the 5GHz band support all of the unlicensed channels available in our region.  For instance, I recently purchased a Nexus 7 tablet and was extremely disappointed to find that it only supports channels 36 to 64 (for the UK). The remaining available channels, 100 - 140 are not supported at all. I think that this variation in support for channels was originally rooted in a lack of support for devices in the UNII-2e channels (c

802.11ac & 5GHz: The Emperors New Clothes? - Part 1

The WiFi industry has been buzzing with excitement around the recently ratified 802.11ac standard. The promise of higher speeds, lower battery usage for mobile devices and the enforced move to the higher-capacity 5GHz band is enough to put a smile on the face of even the most curmudgeonly members of the WiFi fraternity. I've been giving some serious thought recently to what the best approaches might be in terms of designing and deploying 802.11ac networks. There are obviously challenges as we move through the transition from legacy standards to the shiny new 802.11ac standard:  new cabling requirements for higher uplink speeds to 802.11ac APs Increased power requirements for our 802.11ac APs accommodating the mix of new and legacy clients figuring out exactly how we plan our channels for the brave new world of 802.11ac The 802.11ac standard mandates that access points and clients using the new standard will only be supported on the 5GHz band, which is great news

Spectrum Allocation Plans for WiFi in the UK (2014)

Plans for new spectrum allocation for WiFi networks in North America are regular fodder for many blog and news articles that I  see scrolling past in the many RSS feeds that I monitor for WiFi related news. However, information about plans for additional spectrum allocation within the UK isn't quite so widely covered (in fact, I'd go so far as to say that it is largely ignored). But, here in the UK we still face the same issues as many other areas of the world: an explosion in mobile devices, massive deployment of WiFi networks in homes and businesses, and an ongoing increase in bandwidth demands. WiFi in the UK operates on both the 2.4GHz and 5GHz bands. We have 13 channels allocated for WiFi on 2.4GHz, but for practical purposes, only 3 may be used across a wireless LAN. On the 5GHz band, we have 19 channels allocated to WiFi, but are generally limited to using only 16 of those channels due to restrictions in supporting 3 channels that may interfere with weather rada

Aruba Tech Field Day - 802.11ac Product Announcement

Yesterday was the official launch of Aruba's journey in to the world of 802.11ac with their online (and real-world) Tech Field Day event where they presented their products and strategy for  11ac . I was a virtual participant, watching from over here in the UK. I have to say up-front that I do not currently supply or support Aruba products, but was very interested to hear more about their views on 802.11ac, together with their product offering. There was a lot of ground covered, but here a few (brief) notes of things that I found of particular interest for the sessions I managed to view. 802.11ac There was a very informative and lengthy discussion around 802.11ac technology, together with the lessons learned by Aruba in their testing to date. I won't cover all points here, but the headlines that stuck in my mind were: Smartphones/tablets will continue to be primarily single stream, capable of 80MHz bonded channel support Although 11ac brings significant speed a

5GHz - 3 Missing Channels in Europe

Last year, I put up a  posting  which highlighted the fact that here in the UK (and I suspect all of Europe) we often have 3 channels missing from our allocation of unlicensed channels in the 5GHz band.  Looking at many manufacturer data sheets, channels 120, 124 and 128 are often shown as not being supported. This is despite the fact that they are allocated for use by local regulatory bodies (OFCOM here in the UK). I recently posted a question about this on a partner forum of a major WiFi vendor that I deal with and finally got a definitive answer on this. In this post, I'll share my findings. The reason that these particular channels (120 - 128) receive special treatment is that they occupy frequencies that are used by weather radar systems. WiFi systems have to be very careful not to interfere with those systems during their normal operation. Therefore, WiFi equipment has some additional checks and tests imposed on it to make sure that it does not inadvertently cause any int

Samsung Galaxy S4 WiFi Capabilities

With all of the excitement around 802.11ac that is currently unfolding, I was very interested to hear about the support for 11ac by the recently released  Saumsung Galaxy S4. Having a quick scan of the reviews across the web about the new handset, I was intrigued to see claims that it supports 802.11ac, allowing speeds up to 1.3Gbps! Feeling a little sceptical that it would support anything close to those speeds, I did a bit of digging to see what I could find. My first port of call was a product tear-down over at . They revealed that the WiFi chip in the S4 is the  Broadcom  BCM4335 A quick look around the Broadcom site soon revealed the product page for the BCM4335, with an overview of the chipset specification. In summary, it supports: Single stream IEEE 802.11ac solution with  data rates up to 433.3 Mbps Full IEEE 802.11a/b/g/n legacy compatibility with enhanced performance Supports 20, 40, and 80 MHz channels with optional SGI (256 QAM modulation