Today Nigel Bowden (definitely worth a follow on twitter) drew attention to Ofcom’s March decision to open up more spectrum for indoor wifi use.

UNII-3 contains channels 149-161 which so far have been available for use in the UK for outdoor links, required a license (albeit a very cheap one) and Ofcom allowed TX power of up to 4w. This was particularly useful for linking remote buildings, and I know a few people who make use of this band because there’s no risk of building Wi-Fi interfering with the outdoor link.

From 17 August 2017 it’s all change and this spectrum is also made available, unlicensed, for indoor Wi-Fi use. The restrictions are much the same as the UNII-1 band, channels 36-48, with power limited to 200mw eirp.

For most Wi-Fi network administrators this is most welcome as it gives us an additional four 20MHz channels to play with. For high density networks, and demand for the high throughput capabilities of channel bonding the more spectrum we have available the better.

There was a great deal of confusion about all this. It should be noted the language is quite specific regarding outdoor use:

“Equipment must not form part of a fixed outdoors installation when operating in 5730 – 5850 MHz”

Immediately it looked to anyone with a licensed wireless bridge using these channels it was game over and they’d have to use….. something else.

However that’s not the case, this is just very badly communicated.

The channels remain available for outdoor use at higher power levels only with a license, otherwise they can be used indoors only as low power levels…. phew.

This does mean you need to make sure any external APs are in a group that respects the regulatory domain… Not all vendors do a very good job of this.

So officially we can start using these channels on our indoor Wi-Fi from the 17th of August. Whether your client devices will actually use these channels is a different matter. Odds are it won’t take Apple very long to push out an update to iOS and Mac OS with the new regulatory domain information. It might be a different matter for the large numbers of Android devices we see on our network that never have any sort of update. Either way, there’s some lab work and testing to do before putting the new channels into production use.

For more information, see the Ofcom website. The pertinent document is Interface Requirements 2030. Here is the decision statement from Ofcom.

A recurring problem I face in dealing with wifi performance issues is not being able to relocate access points. Asbestos is a problem in many buildings and in some cases adding extra data cabling is so challenging it just isn’t worth it. But… that isn’t always the reason for things not being quite right.

When wifi was first installed it was expensive. It was also 2.4GHz only. You can stick a 2.4GHz AP in a corridor or communal area between several rooms and it will probably provide pretty good coverage. You have relatively few devices to connect. You want to cover as much of the building as you can, you have no money… what would you do?

So the AP is in the corridor, which isn’t ideal in most cases (a topic for another post). But that’s not the biggest problem…

Our original Colubris, and later some Cisco APs had an external omni antenna that could be turned by 90 degrees. So the AP could be mounted on a wall next to the data socket or on the ceiling. A few vendors and models of AP later, we became an aruba site deployed the AP65 and then the AP125. These have built in antennas but they can be rotated to be the correct orientation when mounted horizontally or vertically. They may look a bit weird, but the design is really flexible.

The problem with this is it means we mount APs on walls next to the data socket, because that’s just what you do. When it comes time to replace the AP125 with something newer we bought the version with a built in antenna, just like before, only now it’s a down tilt omni antenna that’s designed to be mounted on the ceiling. It doesn’t flip round. Worse still the back of the later Aruba APs is metal. So when that gets mounted on the wall in a corridor it doesn’t provide very good coverage to the rear. It’s also putting far more energy to the floors above and below than is likely to be desirable.

We’re creatures of habit and once we know how something’s done, we’ll tend to keep doing it the same way. As a result even as new buildings go up, the APs with down tilt omni antennas get put on the wall rather than the ceiling.

Does it make all that much difference? Yes… it does.

In one building I worked on APs designed to be mounted horizontally on the ceiling were, of course, on the wall just above the suspended ceiling grid. They were nice and neat up there, nobody could see them. Unfortunately not many people could use them either and complaints were routine.

A before and after site survey showed that simply re-positioning the AP in the manufacturer recommended orientation significantly improved the coverage in nearby rooms.

We’re now stuck with APs mounted against the manufacturer’s recommendations in some of our buildings for good reason. You may find yourself in the same boat, and you have to make the best of it. However it’s always worth checking whether or not what you’re about to do still makes sense, even if it’s just the way you’ve always done it.

A couple of years ago I started work as a network technician at a UK university. It was an interesting time to join the department with quite a few staff changes, more cash being spent on a network that was struggling and increasing centralising of IT from academic departments.

There was a lot to do. As a team we were firefighting problems daily from dozens of wifi complaints to broadcast storms and OSPF flaps that would take out chunks of the network.

Another recent recruit set about tackling the core network reliability issues, upgrading ancient firmware and fixing network design issues. We were able to upgrade congested gigabit OSPF links to 10Gig and over time things settled down nicely, ready for a major network redesign that has subsequently been rolled out.

Wifi was particularly interesting. In many parts of the campus it worked just fine, until it didn’t. Often that was in accommodation on an evening, when demand was high. Students are vocal in their disdain for inadequate wifi provision. It’s clear there was a problem with wifi, it quickly became clear to me that nobody really knew what that problem was.

The Aruba system had been installed over a few years with an incredibly small budget. That’s an important point, because it’s easy to criticise a poor design. In this case the colleagues who installed the system managed to provide coverage of almost all of the campus with a fraction of the necessary funding. For the most part it had worked pretty well.

I’ve used wifi for years, since the first ‘affordable’ 802.11b systems were available in the UK but I’d never taken the opportunity to understand it properly. When we tried to fix wifi problems in one accommodation block by doubling the number of APs installed in the corridors, I saw an opportunity to make things better… because what we did just made it a lot worse.

I spent a lot of time reading, some excellent blogs, some of the wifi standards, the updated manufacturer design briefs and started to build a picture of what it takes to design a campus wifi network.

My excellent employer then sent me and another colleague on a CWNA course.

So now, though everyone on the team gets involved, I’ve become the guy who deals with most of the wifi support tickets. I’ve redesigned and re-installed wifi throughout some of the most troublesome buildings as well as designing and deploying wifi in new showcase buildings.

This blog is about what I’ve learned along the way, documenting what we’ve done and why, explaining the compromises we’ve had to make and how much that really matters… and probably some other stuff too. For those with knowledge and experience designing wifi networks it’s unlikely you’ll learn anything new here. I’m undoubtedly more a student than teacher, so feel free to tell me where I’ve got it wrong.

Get in touch on twitter @wifi_zoo