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The Wireless Revolution

Andrew Back

Few would argue that a framework governing access to wireless spectrum is required in order to enable efficient use and minimise interference. But it's increasingly being suggested that the idea of spectrum as property — where large chunks are leased for long periods of time to a single user — is outdated, and that a new and far more dynamic scheme governing access is much needed in order to accommodate ever growing demands for this scarce resource.

It's easy to forgot that not very long ago a mobile broadband data connection was the stuff of dreams. And in the space of only a few years we've come to depend on affordable high speed mobile data services that cover our cities and towns. Rather than satiating us this has fuelled our desire, and as time marches on we constantly crave faster connections and quickly become frustrated whenever service is degraded.

As computing devices continue to get smaller, smarter and increasingly connected, and services move online and to the “Cloud”, our need for high speed ubiquitous network access will grow at an even faster rate. And as if this wasn't enough, the Internet of Things (IoT) is set to herald an age where physical objects create and consume data without human intervention.

It's clear to see that, even with the roll-out of 4G mobile networks on the horizon, meeting the needs of humans plus billions of smart objects creating and consuming data is going to be a huge challenge. And it's not simply a matter of bandwidth as traditional mobile network technologies will prove too expensive and power hungry for many IoT applications.

From humble beginnings

If you've ever lived in a densely populated city or been to a conference with thousands of delegates it's quite possible that you've experienced the pains of WiFi congestion. But extreme use cases aside, the provision of the 2.4GHz ISM band for unlicensed use has transformed our lives, and delivered a far greater return than could ever have been achieved had that spectrum been auctioned off to one or a number of users with exclusive rights.

Whilst the 2.4GHz band can be used without the need for a licence this does come with certain conditions attached. These are reasonably simple and reflect its many varied uses and the state of the art of technology at that time — not forgetting that microwave ovens are the original users! However, when newly freed up slices of spectrum are turned over for unlicensed use we get to start all over again, and with the benefit of experiences gained with 802.11 etc. technologies coupled with advances in areas such as cognitive radio, we can plan for much smarter use of spectrum.

White space

White space is the name given to guard frequencies that are allocated between channels or bands so as to minimise interference. And as originally allocated these frequencies are off limits for transmission, but in recent years schemes have been under development that will allow the use of white space whilst ensuring against interference to users of adjacent spectrum. Again, this is made possible by advances in cognitive radio whereby systems are able to listen out for other users and give preference where appropriate, and by enabling equipment to update real-time geolocation databases in order to bring about highly coordinated spectrum access.

Cambridge (UK) based company Neul are championing technology for providing unlicensed access to television white space spectrum, whilst also leading a key standardisation effort, Weightless. With equipment already in trials, Neul plan to have custom silicon for terminal devices down to $1 by 2014. Uses for this incredible technology ranging from low bandwidth machine-to-machine (M2M) communications for IoT type applications, to rural broadband at data rates up to 16Mbps, and all whilst covering distances of up to 10km.

The march of deregulation

The idea of spectrum deregulation is not new and staunch advocates such as Lawrence Lessig — a campaigner and professor of law perhaps best known for his work on Creative Commons — have been calling for this for some time. But it would seem that finally the message is getting through, and a recent article in the New York Times reports that President Obama is being urged to rip up “policy that was really set in motion by technology of 100 years ago”, with claims that spectrum management efficiency could be increased by a factor of 40,000. Citing a European study that found that using new technologies to share just 400MHz of spectrum would provide financial stimulus equivalent to 800 billion euros.

It could just be that the humble wireless LAN has sowed the seeds for a revolution in spectrum access, which will be driven forth by white space solutions, and that is set to bring about a new dawn in communications. And one thing is for sure: it's a good time to be an RF engineer!

Top image: Gliwice Radio Tower by Mariusz Cieszewski (Flickr: PolandMFA), CC BY-ND 2.0.

TV image: copyright Neul Ltd.

Open source (hardware and software!) advocate, Treasurer and Director of the Free and Open Source Silicon Foundation, organiser of Wuthering Bytes technology festival and founder of the Open Source Hardware User Group.

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June 2, 2013 10:27

what I do is select only one type of rule or a minimun set of them so teh number of errors are limited to only some rules. Then solve part by part ap to get no errors. I start with placing rules up to get no errors, later routing. If I have to move parts to allow better routing then I run placing rules again, and so on. Soem times is better dinamic rule check if only one ot two erros have to be fixed. If not interested in solve some problems you can erase all errors unselect the rules not interested and go on with the process.
I do not know better process, may be another people have better solution.

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June 2, 2013 09:24

I pasted in several fairly small schematics until I reached the limit. Then I pasted several others into another sheet, Only 2 sheets

How do I get rid of the every component error ?

That would be really good

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June 1, 2013 07:55

DRC is a powerful tool to keep design in order to met standards. You may select in tool->Design rule check which rule is relevant for you in your actual design state. For example, turn on connection rules when not routed yet will fill the report of unmeaning errors, you may swicht it off whhile placong parts in your design.
I ussually turn on spacing rules whyle I'm placing parts inside the board. Then after routing turn on nets and later the manufacturing tools. Nevertheless, the DRC is defined in Settings->Sesign Technology slide Spacing and Rules.

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May 31, 2013 05:46

Any ideas about what to do or how to fix this little Jem? It seems to have a problem with every component... Smaller single sheet schematics using the same parts libraries have no problems.

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