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What Are Whitespace Devices?

Whiteboard Session
February, 03 2016 |

Shure UK Pro Audio Group Manager, Tuomo Tolonen explains what whitespace devices are.

Not so long ago Ofcom approved plans for  Whitespace Devices to share spectrum with digital TV and wireless  microphones. As a relatively new development in the ongoing debate about  the future of spectrum, Whitespace Devices are often overlooked or  misunderstood. In this week's whiteboard session, we cover what  whitespace devices are, why and where they operate, and how they cause  some concern for wireless microphone users.

Over the past few weeks, we've explained through various videos how  regulators continue to reallocate RF spectrum for use by next generation  4G mobile data services. Whitespace Devices are yet another layer of  pressure for the PMSE sector that professional operators need to  understand. But first, we must define what exactly white space is from  an RF standpoint.

The term white space is used within the context of RF to describe  portions of spectrum that are not in use. As wireless microphone  operators, we share portions of UHF spectrum with digital TV; the  sections in between these TV channels are referred to as white space  (demonstrated in the chart below). For many years, users of wireless  microphone systems and in-ear monitors have made excellent use of this  so-called white space, and we've always operated at a tier below  broadcasters.


In the eyes of regulators, these white spaces could be used more efficiently. Let me explain:

If we were to take a snapshot of how much white space is used in  London by the PMSE sector at say 5 in the morning, there would likely be  little activity. As the day goes on, however, the usage by PMSE goes up  as events and broadcasts happen throughout the day. Peak usage is  likely between 6 - 10pm as West End shows and concerts take place across  the capital. During these peak operation times, white space spectrum is  heavily populated with wireless mics and in-ear systems, but at other  times of the day these areas are clear for operation. In a nutshell, TV  broadcast stays consistent while PMSE usage fluctuates — creating  downtime.

To make more efficient use of this so-called white space during  periods of downtime, regulators have conducted research into further  usage of white space, and this is where Whitespace Devices come in.

What are Whitespace Devices?

There is no concise answer to this question, as there are currently  multiple uses for Whitespace Devices. One example is so-called 'super  WiFi,' which essentially works in the same way WiFi does today only over  much greater distances. Another use of Whitespace devices ties in with a  term we increasingly hear called 'The Internet of Things'. This term  essentially describes how all the devices we use on a day-to-day basis,  from the electricity in our homes to common traffic management systems —  and everything in-between — could be interconnected for efficiency and  more. Put another way, this is sometimes referred to as  machine-to-machine communications, and it will work by using the same  white space as wireless microphone and in-ear monitor systems.

In theory, you can see how this seems like a great concept. But  hopefully, you can also see how this news is of concern to the PMSE  industry. Following the recent news of clearance from 694MHz and up  (likely starting from 2019), we've already been left with significantly  less space to operate than in previous years. Whitespace Devices are yet  another service sharing the remaining UHF spectrum, and given the  mission-critical nature of many wireless microphone applications, this  development is of great concern.

Here's how it'll work:

Earlier, we briefly touched on the hierarchy or tiers applied to UHF white space, which looks a little something like this:

Tier 1) DTV

Tier 2) PMSE

Tier 3) Whitespace Devices

DTV will continue to have priority over PMSE while Whitespace Devices  will operate at a tier below PMSE, which is good news for us. Put  simply, Whitespace Devices are not permitted to operate in a clear  portion of UHF spectrum if it causes harm to PMSE transmissions.

This three tier system will be managed using a geolocation database.  This cloud database will host the licence information of PMSE, and if a  Whitespace Device wishes to operate at a given UHF frequency, it must  first check the database. If the database can prove that wireless  microphones or in-ear monitors are operational, Whitespace Devices will  not be permitted to operate. Protection is there, but the key is to  licence your systems.

Details on wireless system licencing is a topic for another day. The  short answer, however, is that to properly protect yourself from  Whitespace Devices, you need to obtain a licence and put yourself on the  map.


Learn more 

We hope this overview of Whitespace Devices goes some way to  explaining this complex topic.To learn more about wireless systems and  best practice operation, consider attending one of our Wireless Mastered  seminars, or our Wireless Workbench masterclass.

Marc Henshall
Marc forms part of our Pro Audio team at Shure UK and specialises in Digital Marketing. He also holds a BSc First Class Hons Degree in Music Technology. When not at work he enjoys playing the guitar, producing music, and dabbling in DIY (preferably with a good craft beer or two).