Broadcast/Mobile Broadband convergence – the slow road to nowhere?

EC Spectrum Policy Workshop -Broadcast/Broadband convergence 04 November 2014, Brussels

As part of its policy deliberations on the long-term future of the UHF bands, the European Commission commissioned a study on the options for Broadcast/Mobile broadband convergence. The findings from this study follow the report from the working group led by Pascal Lamy. The Lamy report recommended that broadcasting be cleared from the 700 MHz band by around 2020, with security given to broadcasting in the remaining 470-690 MHz until at least 2030 – with a review of the situation in around 2025.

The study whose findings were presented in the workshop reviewed a number of options for rolling back traditional broadcasting and introducing a ‘mobile-friendly’ downlink into the UHF band below 700 MHz (after rejecting options using the band above 700, except to provide an uplink). This downlink would displace the traditional high tower/high power broadcast network but could use DVB or LTE technology (which would use lower power lower tower deployment, supporting the greater coverage density needed to achieve a greater mobile user satisfaction).

In summary, the study found that the technical and regulatory foundations for convergence were not yet in place sufficiently to get a clear picture of costs and benefits. It recommended further work on the technical foundations and a further review of the situation in 3 to 5 years’ time.

Given the slow pace of work on the 700 MHz band, together with lack of clarity on the technical foundations for broadcast/mobile broadband convergence (and the commercial interest needed to make it happen).

Meanwhile convergence is moving quickly for mobile device users, with Wi-Fi being the predominant network technology for delivering audio and video services to mobile devices of all shapes and sizes. LTE is integrated in nearly a fifth of tablets and this figure may grow, but the purchase cost penalty (typically an extra £100 on an iPad, for example) will likely limit the share of market achieved. On the other hand, the lower cost Wi-Fi will be built into an increasing range of mobile/portable devices – including cameras and other types. Wi-Fi has a clearer roadmap, with fewer bands and variations to burden implementation, so it seems likely to remain the network interface of choice for mobile/portable applications for years to come.

In Europe at least, we’d have to agree with Pascal Lamy that there is little prospect of broadcasting being rolled back below 700 MHz much before 2030. Even the likely clearance of the 700 MHz is likely to last into the 2020s, with a number of administrations and broadcast network operators still feeling the pain from the 800 MHz clearance.

In more detail

The study team (which included ex-Ofcom William Webb) evaluated the costs and benefits of the various options for convergence – in so far as data was available. A few problems were identified:

  • They found it difficult to get data on converged viewing vs linear TV viewing…. need better measurement methods
  • The standards that might be used e.g. LTE Broadcast , have not yet defined (work for 3GPP to do)
  • The broadcast-related re-engineering costs are difficult to estimate, given diverse market and conditions across the EU
  • The spectrum yield that might arise from moving to all-Single Frequency Network (SFN) broadcasting is not fully pinned down
  • A period of simulcast would be required, but it isn’t clear where the spare spectrum would come from
  • WSD and PMSE users would see their capacity in UHF reduced – they would need to look elsewhere for additional capacity
  • Pinning down the value of spectrum (in terms of auction price) is difficult and evaluating its wider economic and societal benefit is harder still

The main options considered were around reallocation of sub-700 MHz spectrum from conventional DTT broadcast to some form of mobile-friendly unicast, from 2025 onwards. Making the unicast downlink-only reduces risk of interference to DTT receivers and in home TV distribution systems. The study team assumed that uplink for interactive services would occur in the bands from 700 MHz upwards. The team also assumed that EU member states would have moved to the more efficient DVB-T2 and that SFNs would widely adopted* by the time these options would be introduced, to provide the necessary capacity flexibility.

The technology that would be used for the unicasting is open at this point. LTE-Broadcast is not yet defined, but DVB-T2 could deliver a high level of spectrum efficiency (~5 bits/Hz).

*Qualcomm commissioned a report from ADTI on how low power SFNs could help free sufficient spectrum and hence create flexibility for progress on convergence. 

White spaces made easy - thanks to DSA Model Rules

Members of Regulatory Affairs group of the Dynamic Spectrum Alliance (DSA) have been putting their heads together to review regulatory practice across the world, on access to the TV white spaces and have assembled a Model set of rules. Most of the development work on regulations has been undertaken by the FCC and Ofcom (UK), working with industry.

The intention is to help administrations which have not yet investigated introduction of TV white spaces technology to get up the learning curve faster. The documents provided on the DSA website include:

  1. The Model Rules backgrounder introduces the significance of access to the TV white spaces and the key components of the sharing mechanism designed to protect existing users of the band, namely terrestrial TV viewers and wireless microphone users
  2. Suggested Technical Rules and Regulations for the Use of Television White Spaces

  3. Frequently Asked Questions 

The model rules are based around the use of geolocation databases, with white space devices reporting their positioning in order to determine what spectrum is available to use. They include the concept of master and client devices, where the master device acts an intermediary between client devices and databases. Clients need only consult their local master device in order to determine which channels are safe to use.