You are in:
White space: the final frontier
Andrew Fell from TTP looks at how white space spectrum could be used to help meet the growing demand for wireless data and improve emergency services communications
Today’s emergency services demand more and more communications capability, in a similar way to data hungry smart phones providing users with internet everywhere. But there is one major problem. At large emergency scenes, the cellular infrastructures that the emergency services rely upon often struggle due to sheer weight of traffic, which renders communications between public safety personnel limited and ineffective just at the time it is most required.
The fact is that in the UK and Europe there is not enough spectrum available for emergency services to support the large amounts of data transfer that are required during a major incident.
Imagine a new communications technology that can be deployed on scene to provide long range, fast data communications between blue light services. Imagine on-scene high definition video relayed between team personnel and sent back to central points; location based technology for personnel tracking; and inter-team wideband communications to assist with efficient management of resources.
All this could be possible with the introduction of what is being called, “white space” technology.
What is White Space?
The words you are reading right now are separated by spaces known as “white space”. Although these spaces contain no information, they ensure the words do not interfere with each other. Without these spaces, this article would become extremely difficult, if not impossible to read. Now imagine that a machine readable message is written within these spaces, perhaps in a very light grey colour, such that it does not interfere with the overall readability of the main message. Filling the spaces with more information is making more efficient use of the paper.
Such spaces also exist in radio spectrum, and occur in the frequency, time and space domains; particularly those frequencies used by television which are suited for long range radio communications, as opposed to the short range performance currently suffered by wireless systems at 2.4GHz, like WiFi or Bluetooth.
What is TV White Space Spectrum?
Some of the most abundant and valuable white space spectrum is a result of the necessary planning of terrestrial broadcast television. If you’ve ever had the patience to watch your television tuner search for available signals, you will notice that many of the channels are seemingly empty. In the UK, each television channel uses 8MHz of spectrum and the empty channels in a given location soon add up to large swathes of prime spectrum that could be put to good use. The good news is that it is technically possible to deploy low power transmissions inside these spaces without perceptibly interfering with the primary users.
TV White Space and Regulation
On 1st September 2011, OFCOM announced its intention to regulate TV white space spectrum as a free resource and is currently investigating regulatory schemes for its use. It is highly likely that other worldwide regulators will do the same, following in the footsteps of the FCC in the US and OFCOM.
White space devices will need to access a geolocation database to ascertain the channels that are available for use at that particular time, in the geographical area in which it requires to operate. These databases will be government regulated and will have the power to determine whether or not a transmitter is allowed to operate as requested. This means that for public safety systems the geolocation database can give priority to emergency services where on-scene wide band communications is a transitory requirement, thereby - and only if absolutely necessary - halting other secondary users until the emergency has dissipated.
Use of White Space for the public safety industry
For the majority of scenarios, many of these 8MHz TV white space channels are available – over 100MHz in most parts of the UK. Such spectrum availability, especially if prioritised for public safety use by government legislation, could provide the backbone for emergency communications, giving performances far exceeding existing systems. Pop-up networks could be rapidly deployed and entirely configurable for their intended use, even securely encrypted, thereby removing the current dependency on existing cellular networks. What’s more, there will be no license and no data charges to pay, because this spectrum is free to use: ideal for today’s public purse strings.
The recent move to Digital TV transmission opens up freely available white space spectrum. This, combined with the technology advances, including the evolution of software defined radio, miniaturised GPS receivers and the growing capability of embedded computing power; means that engineers can design high speed, highly dynamic and wide bandwidth radio systems that learn from and adapt to their surrounding environment. And all this is possible within small space envelopes integrated into existing equipment. Prototype systems are already being trialled in Cambridge UK, for machine to machine and broadband applications, entirely applicable to emergency services use. Out are the old draconian rules of spectrum management, as useable channels that many people never knew existed will gradually be revealed.
Andrew Fell
Andrew is a radio design engineer and project manager at The Technology Partnership (TTP) with over 16 years of product development experience across a wide range of industries, including government. He has a lead role in TTP’s wireless activities, particularly around White Space technology, and is responsible for TTP’s rural broadband trial within the Cambridge TV White Spaces consortium.
