DTT and Wireless Mics Win Out at WRC23

The decision, taken at the 2023 ITU (International Telecommunication Union) World Radio Conference (WRC-23) in Dubai, is also good news for wireless microphone users in both broadcasting and live event production.

Radio mics, in-ear monitors (IEMs) and wireless communications come under the umbrella term of programme-making and special events (PMSE - specifically audio PMSE to differentiate it from video applications such as wireless cameras) and have become a crucial part of TV programmes, particularly large-scale productions.

Coverage of the Olympic Games, the Eurovision Song Contest and major, annual light entertainment shows such as Strictly Come Dancing rely on the technology and there were fears that any further reduction in the amount of spectrum allocated for wireless mics and associated devices would seriously affect established production values.

Commenting on the decision at WRC-23, DTG Chief Technology Officer and national PMSE working group lead Alex Buchan said: “Overall the outcomes of WRC23 are good news for the DTT and PMSE sectors, providing regulatory stability while offering continued access to the spectrum. That is not to say there were not some compromises, which include a secondary allocation for mobile in the 614-698 MHz band and a review of broadcasting spectrum at WRC-31. The DTG through its PMSE and (TV) Distribution working groups and 5G project work will continue to lead discussions with industry to ensure the results of these compromises are fully explored, understood and workable.”

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The DTG (Digital Television Group) has been a major force in UK digital TV and takes an active role in promoting the importance of spectrum for both DTT and PMSE.

Spectrum Reduction for Audio PMSE

The allocation of spectrum for audio PMSE has changed considerably since the late 2000s, with the number of radio frequencies (RF) available for wireless microphones and IEMs being severely reduced in that time. This process began with the clearance of the 800MHz band, which for many years had housed both PMSE and analogue TV channels. For UK wireless mic users the big impact was the loss of the national channel 69 frequency, as well as other frequencies in different regions.

Lobbying by the industry as a whole, including the newly formed BEIRG (British Entertainment Radio Industry Group, comprising wireless mic manufacturers, broadcasters, rental companies and end-users), secured many concessions from the then government, including channel 38 to replace channel 69 and compensation for those forced to buy new equipment.

PMSE also gained access to frequencies in the 700MHz band, which appeared to offer a secure new home for wireless mics and IEMs. By 2013, however, when the last of the 800MHz band had been auctioned, the mobile phone companies that had bid for frequencies to develop new services, including LTE (long-term evolution) and mobile broadband began to call for more spectrum. WRC-15 later agreed that 700MHz should be given over to 4G and 5G mobile phone services and new technologies such as the Internet of Things (IoT).

Another round of lobbying by the PMSE sector across Europe secured space in the UHF spectrum, with the UK retaining channel 38 and additionally having access to the DME (distance measuring equipment) band covering 960-1164MHz, also known as the Air Band because parts of it are used for commercial aviation equipment. The white space between DTT channels in the UHF band between 490-698MHz is also available to UK PMSE operators, as it was with analogue TV, although, as Duncan Bell of Wideband Consulting and a member of the BEIRG steering group has pointed out, the amount of this interleaved spectrum that can be used for wireless mics has already shrunk across the country.

This situation, combined with an increasing demand for wireless mics on broadcast and event productions, means that spectrum continues to be in short supply for PMSE. Jonathan Edwards, Head of RF at UK wireless system rental company

Terry Tew Sound & Light, has commented that coverage of the Coronation of King Charles III would not have been possible without the use of DME due to the high demand for spectrum at the event.

Because DME/Air Band is only available for PMSE in the UK, it is not a solution to the overall spectrum problem in Europe. Digital technology has made a huge difference to the operation of wireless microphone systems, offering better spectrum efficiency and allowing for more frequencies within one TV channel. Even so, broadcasters still struggle to obtain enough spectrum for their needs. Which is why there was concern, if not despair, when it was announced that WRC-23 would consider proposals to change the priority for allocating frequencies in the 600MHz band for ITU Region 1 (Europe, Middle East and Africa).

The situation before WRC-23 was that DTT had primary status in the 600MHz band, with PMSE having a secondary position but still recognised as important. Three proposals on the agenda at WRC-23 were: there would be no change to the present arrangement; that the mobile telephone sector - known as mobile IMT (international mobile telecommunications) because wireless mics are also classified as mobile - would gain secondary status, putting it on the same level as PMSE, with the option to go to primary in the future; or mobile becoming co-primary with DTT and PMSE remaining secondary.

WRC-23 – Positive Steps

The outcome was essentially ‘no change’, although mobile phone allocations within each country of Region 1 were made in footnotes to the main statement. DTT is still the solitary primary user of UHF TV frequencies in Europe, while PMSE has its own secondary frequency allocation in 88 countries. If frequencies are allocated to mobile IMT in individual states, they would be subject to strict requirements for securing broadcasting, while also co-ordinating with neighbouring countries.

The Alliance for Broadcasting and Cultural Frequencies (ARK), which includes German broadcaster ARD, the Save Our Spectrum initiative and Sennheiser, welcomed the decision. ARK was formed to protect the long-term use of UHF for broadcasting and “wireless production means”. In a statement it highlighted the fact that there will not be any review of the use of 600MHz until WRC-31, as there were concerns that the matter could be on the agenda at the next conference in 2027. ARK added that, “For the studies for this [WRC-31], the consideration of wireless microphones was expressly stipulated.”

Sennheiser attended the conference and was official audio sponsor of the US reception held during the event. This included a live performance by the rock band Sonic Crusaders, who used a prototype IEM system based on Sennheiser’s WMAS (wireless multi-channel audio system) technology, which is designed to allow more audio channels to be multiplexed into one wideband frequency. Another leading wireless mic manufacturer, Shure, was heavily involved in the work leading up to WRC-23 and also had a strong presence at the conference, including a booth showcasing the importance of the 470-694 MHz band for PMSE.

Wolfgang Bilz, head of spectrum and regulatory affairs for Shure in Europe and co-chair of the Association of Professional Wireless Production Technologies (APWPT), describes the outcome as “positive”, because, going into the discussions there were differing positions within ITU Region 1. Most of Europe was in favour of secondary status for IMT while Africa and Eastern Europe favoured no change, with Arabic countries opting for both allocation to mobile and identification of mobile IMT.

“There were the two extremes: no change and mobile IMT identification,” he explained. “The middle ground was secondary mobile allocation. This makes sense because all the ITU member states have to sign the final agreement and everything is based on consensus. The most important point is that there is no blanket mobile allocation in the table of the radio regulations or frequency allocations for Region 1. There are only footnotes, with countries added that want to support mobile or mobile IMT.”

Bilz added that the expectation is there will be very limited deployment of mobile IMT or 5G technology over the next ten years in the 614-698MHz band for Region 1. “There is only a handful of countries listed in the footnotes as starting with identification of mobile IMT, including United Arab Emirates, Saudi Arabia and Egypt,” he said. “But the second very important item is that we have a footnote listing PMSE in the 470-694MHz band as a land mobile service. There was also the resolution that set a review of the decision for WRC-31 and also said there should be enough spectrum for PMSE in future.”

This last recommendation is in stark contrast to the early days of the 800MHz reallocation process, when the position and importance of PMSE was barely recognised by governments and regulators. Duncan Bell was involved in those initial discussions through BEIRG and has seen the attitude towards the wireless microphone sector change significantly. “It is important to recognise that the consistent pressure from organisations like BEIRG and APWPT, or directly from the manufacturers really has gained some traction,” he said. “Just the language in some of the documents at a summit like WRC-23 refers to and recognises PMSE in a way that they never used to. Now there is a much clearer recognition of the scale and value of PMSE.”

Bell agrees that the outcome of WRC-23 is encouraging for PMSE but the nuance is to make it clear that the issue of pressure on spectrum access is not going away. “The fact that there is no blanket allocation within 470-698MHz for mobile in Region 1, despite significant pressure for a co-primary allocation, is positive. But we still need specific policies that recognise and address PMSE’s core requirements for the future. For many years PMSE has had the protection of the TV networks because it operates in the white space between the DTT channels. If you take away DTT you take away that protection. So PMSE needs a solution that ensures the ability to create and capture content regardless of the changing landscape of DTT.”

DTT Across Europe – a Mixed Picture

The debate over the future of DTT in the face of streaming, IPTV and mobile video services continues to be had in Europe. Switzerland has already shut its DTT network and Finland is considering following suit but countries like the UK still have a large viewership for the platform, particularly among the older generation. Consequently the UK government has agreed licence renewals for DTT until at least 2034, with the Broadcast 2040+ campaign, as its name suggests, looking to extend that further.

The positions of both DTT and PMSE in the RF spectrum are secure not only for now but for some time to come. Those in both areas know, however, that there is nothing to take for granted and there is still work to do for when the next frequency review for digital TV and wireless microphones comes around.

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