5.3.4 Radio Microphones

There are existing radio microphone services operating in the UHF bands and provision for these types of short range systems will be required in the future. The licence for these services allows them to be operated on a non-interference basis in the frequency ranges 518-582 MHz and 614-806 MHz. These ranges were authorised in May 2009, but it is likely that most equipment is operating within a narrower frequency range, 646-806 MHz which was previously authorised.

The Ministry received many responses to its Digital Dividend in New Zealand Scoping Paper of May 2009 from providers and users of radio microphone services.

The two main requests have been for:

• adequate continuity of use of the current 698-806 MHz band for existing equipment, and
• a clear space of 100 MHz to be provided in the 519-698 MHz band in the future for orderly transition.
  

Radio microphone service providers advise that many microphone channels are required, for instance up to 50 channels might be required for a major sporting event.

There is some recognition that internationally that use of the “white space” between the television channels is generally satisfactory. However this may become more difficult in the future as the greater technical efficiency of digital television use allows n + 2 main station channelling, and n+1 for main and infill services. Each microphone channel must be spaced 1 MHz apart from others in the same location to avoid overloading and inter-modulation. The Ministry does not consider the request by some radio microphone users for 100 MHz of clear spectrum to ensure the continuance of this service in New Zealand is a viable outcome. This may be a perceived ideal outcome for a radio microphone user, but is impractical in the face of realistic demands for spectrum. Radio microphone users clearly place a high value on their use, although there is currently no fee involved in such use and the extent of economically sustainable demand under a contestable allocation process is unable to be evaluated.

Options to facilitate use of radio microphones should desirably allow as many as possible of those existing today to continue. However it is a recognised condition of licence that radio microphone use must not cause interference. Inherently this requires changes by the unprotected users as other licensed and protected services develop.

Options for ongoing radio microphone are considered to be:

• to provide for an exclusive, although relatively narrow, part of the UHF band for exclusive use; and/or
• to provide a general licence for “white space” use in all or part of the “television” parts of the revised band; as well as
• a transition provision to provide a general licence for “white space” use in the “dividend” part of the revised bands, to recognise that most existing users were likely to have equipment operating in this spectrum and may have limited frequency agility.
  

It is however considered neither necessary, nor efficient to allocate a clear 100 MHz block of spectrum for radio microphone services and the use of a single exclusive sub-band for such use is also seen as unsatisfactory because of interactions between radio microphones that are close in both frequency separation and geographic proximity. The Ministry aims to allocate the UHF digital dividend spectrum in such a way that provides the maximum benefit to society. The Ministry therefore believes that a more efficient allocation of spectrum for these services may be achievable without substantially increasing the risk loss of utility for such uses.

This option would involve the use of “white space” for short range devices such as radio microphones, but over a wider frequency range than has hitherto been authorised. “White space” is the unused spectrum that is interleaved between television broadcasting channels (or other uses). High power services are not possible in these parts of the spectrum due to the risk of interference, but the use of low power applications is feasible. This is the approach taken by Ofcom in the UK.

The Ministry has recently (June 2009) created licences to allow radio microphones to operate over the whole existing UHF television frequency range (excepting the Management Right owned by MTS). This allows much greater flexibility of frequency usage and effectively implements one of the options considered above. The new licences can be viewed in the Ministry SMART online system, www.rsm.med.govt.nz under Licence ID No. 130244 and No. 130245.

Over time it should be expected that all radio microphone users migrate from the spectrum that is proposed to be allocated on an un-encumbered basis for nationwide use. The Ministry is aware that a frequency change would require, in some cases, new capital expenditure for these users and therefore aims to allow radio microphone users or service providers an adequate period to make any frequency change that might be required of them.

Question 15

Are the current new licences for radio microphone use in the band 518-582, with potential future extension up to 698 MHz, adequate for ongoing use after DSO? If not, what other provision should be considered?

It may still be necessary to consider providing for existing usage of the former 646-806 MHz range, for a period after DSO. Even if part of this spectrum is reallocated, existing uses can be provided for by creation of spectrum licences prior to the sale of the management rights.

The Ministry considers it appropriate to limit new equipment from being used in the spectrum to be sold on a nationwide basis, with effect from the time of decisions being made about the relevant frequency limits. This could be from late 2009, but would probably practically be best applied from the March 2010 expiry of the present licences.

Assuming that DSO were to occur in 2015, there would be a five year period to allow for transition of existing uses from the released spectrum. Even if DSO was to occur earlier, a five year period is considered necessary.

Question 16

Do you agree that new radio microphone use should be restricted in the nationwide released spectrum with effect from 2010, and existing use discontinued after five years, as transitional measures? If not, what other provision should be considered?