Hanns Wolter, Technical Director, Club DAB Italia and WorldDAB Regulation and Spectrum Committee, Chair
Spectrum for digital radio in Europe was allocated a long time ago, starting with the Wiesbaden Plan in 1995, and it has been always been considered as a certainty. Recent developments have shown that everything could be reconsidered and modifications of international agreements are implemented shortly after being adopted.
When important parts of broadcasting spectrum are co-ordinated for another use, it consequently raises issues over whether the amount of spectrum currently allocated is enough for future developments of DAB.
Band III in the range 174-230 MHz is the most important spectrum for DAB and it could be called the core band for digital radio. The amount of spectrum is 56 MHz and the plan for DAB in the band is included in the Geneva 2006 Agreement. Digital radio is already implemented in this band and it is confirmed that propagation characteristics of this range of spectrum are the most suitable for digital radio.
The serious limitation of the band is that some channels are already allocated for digital TV. There have been considerations about the transformation of the TV channels into DAB blocks but as TV had to abandon both the 800 MHz band and now the 700 MHz band, it is expected that TV will again use band III in some countries.
L-band was originally reserved for satellite digital radio and DAB was allowed in the lower 27.5 MHz of the band. One to three nationwide multiplexes were planned for each country in the last revision of the Maastricht 2002 Plan adopted in Constanta 2007. For a long time, L-band was unused because parameters didn’t allow using it as the basic spectrum for DAB introduction. Currently the band was harmonised in Europe for supplemental broadband download and only one country is using it for digital radio. European decision does not allow introducing new radio stations here and only already operated stations are protected. Eventually this band will be allocated to pure mobile broadband services with 4G technology.
Therefore we can say that currently DAB has access to some parts of Band III only. Available spectrum usually allows operating of the public broadcaster multiplex and a limited number of multiplexes for commercial broadcasters depending on the national situation. It becomes more complicated when satisfying the needs of nationwide and regional broadcasters. It is evident that in a number of areas, not enough space is available for local programs.
We also expect that not only will all analogue programs be moved to digital but that we will have many new digital programs. So the capacity of multiplexes which was assumed as huge could be exhausted quickly.
Looking for more spectrum for DAB looks to be valid issue.
A) In Band III
The first possibility is to use channels that are not planned in Geneva 2006. The problem with the Geneva 2006 Plan is that it does not take into account terrain. Usage of site in distance from national border, with mountains between the site and another allotment, using antenna pattern, limited power, could lead to successful coordination of more sites allowing regional or local coverage.
Also planned channels could be coordinated for other areas, results are depending on local circumstances.
B) Outside Band III
The second option is using the channel 13 (230-240 MHz) depending on national circumstances. Chester Agreement also planned channel 13 for DAB in some countries. Problem is that these frequencies are used by the military sector and coordination on both national and international levels is needed. As broadcasting freed spectrum for mobile applications it is reasonable to ask channel 13 as compensation for it. In some countries the military is asking access to spectrum below 230 MHz and it brings also argument for broadcasting to be interested in the 230-240 MHz range, which offers 6 DAB blocks.
C) Band II
There will be no more additional spectrum for broadcasting in the future, all applications are looking for spectrum below 1 GHz.
We should protect and take care about spectrum, which is already allocated to the Broadcasting service.
Band II is blocked by extremely high utilisation and no future development is feasible. The solution is to move programs to digital radio multiplexes, a process which can free the band. What will happen then? Experiences with the TV spectrum shows us that there will be a row of applicants for future use of the band and it is possible to identify some of them now – mobile sector, aeronautical sector, both are using similar frequencies nearby. It is time now to prepare future use of the band by broadcasting.