Introduction

Sharing TV spectrum with new licence-exempt wireless applications

What we're doing

The BBC has been researching the use of TV White Space (TVWS) for 4 years. TVWS is the interleaved radio spectrum in the UHF broadcast band (470-790MHz) that can be used for low power applications at a particular location. Typical applications include wide-area Wi-Fi coverage, machine-to-machine (M2M) networks (e.g. for smart meters and remote sensors) and rural broadband connectivity. The amount and quality (e.g. the noise floor) of TVWS spectrum varies across the country and accessing the spectrum requires a geolocation database. Ofcom are developing a regulatory framework to enable the use of this spectrum and have been consulting on this since 2009. The Ofcom framework development is expected to conclude this year, allowing licence-exempt access to the TVWS from 2014.

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Why it matters

The TVWS is a new spectrum opportunity, which could support a range of new applications for broadband, machine-to-machine and home streaming. The new applications carry a risk of interference to existing services and a balanced approach is necessary. The key concerns are:

  • Protection of DTT Freeview and Freeview HD services where the BBC has made significant long-term investments.

  • Protection of the interleaved TVWS spectrum for Professional Wireless Microphone Systems (PWMS), which are needed for Programme Making and Special Events (PMSE).

Our goals

This year, we plan to

  • Conclude the work in the Ofcom Technical Working Group (TWG) and support BBC Distribution with the BBC response to the anticipated consultation on technical parameters for TVWS access.

  • Document the findings of our studies in BBC White Papers.

  • Participate in the Ofcom TVWS Pilot commencing Q4 2013.

  • Develop tests within the DTG D-book to improve the resilience of TV receivers to WSD interference.

  • Participate in the new, DTG-led group known as the Dynamic Spectrum Access (DSA) group, which is considering further trials.

  • Explore applications for TVWS that could potentially benefit TV broadcasters and viewers. These include wireless streaming of media in the home and Internet connectivity to support online services like bbc.co.uk, iPlayer and second screens.

  • Develop a hardware demonstrator using Linux PCs and DVB radio standards so we can assess the capabilities of TVWS spectrum for wireless applications in-home.

  • Use software defined radio platforms to prototype these applications.

How it works

The amount of TVWS spectrum and its quality vary with location. Devices will use a location service (e.g. GPS, Wi-Fi, Mobile Networks) to know where they are and will then access a database to discover what channels can be safely used at their particular location. The database must take account of DTT broadcasts (e.g. Freeview services), which are fairly static, and PMSE assignments, which are more dynamic. The database could also co-ordinate TVWS users to maximise the performance of the new application, but this is not a regulatory requirement.

The rules for accessing the spectrum and protecting the incumbent users (DTT and PMSE) are complex and are the subject of consultations between Ofcom and the stakeholders. Propagation models and knowledge of the incumbent receiver performance are needed to calculate appropriate power limits for the WSDs. To ensure the rules are fair and correct we respond to Ofcom's consultations and participate in international work (e.g. the CEPT SE-43 study). The aim is to protect the investments made by the BBC in the DTT platform, meet our requirements for programme making spectrum whilst maximising opportunities for new applications.

To understand the capabilities of the technology we also participate in field trial and pilots working with Ofcom and other stakeholders. Our findings are documented in white papers and conference publications.

Outcomes

  • Protection of DTT services to ensure reliable TV reception.

  • Protection of PMSE spectrum needed for programme making.

  • Development of TVWS applications relevant to broadcasters, viewers and listeners.

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