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Studies on the coexistence between DTT and mobile networks in the UHF band

With the completion of the analogue switch-off, the UHF band has been entirely used for digital terrestrial TV (DTT). Following the European decisions, from 2013, the first digital dividend at 800 MHz (790-862 MHz) was released to fourth generation mobile (4G). Today Europe is seeking to release an additional spectrum portion in the 700 MHz (694-790 MHz) for 5G uses by 2020.

 

The opening to the mobile service of bands traditionally used by other services requires careful analysis of the possible compatibility issues, referring to the sharing of the same spectral resources in different geographical areas, such as between neighboring countries, and the coexistence on the same area between systems that use adjacent frequencies.

 

To carry out the coexistence analysis suitable for the Italian scenario, several peculiarities need to be taken into account, including the intensive use for television of the entire UHF band, the presence of SFN networks operating on channels adjacent to frequencies intended for mobile, the lack of knowledge of the characteristics of households’ TV reception systems.

 

As far as the 800 MHz band is concerned, the Foundation has conducted theoretical studies on coexistence between television and mobile systems, within the working gropu set by the Ministry. In addition, FUB has developed a descriptive model of TV reception systems adopted in Italy, also relying on laboratory tests and has collaborated on field trials for the assessment of the interference effects due to the introduction of LTE in the 800 MHz band.

 

Currently, the Foundation studies the possible interference effects due to the release of the 700 MHz band, which may also suffer from the adoption of misaligned transition calendars in neighbouring Countries. Misalignments can cause additional cross-border issues due to pre-existing television networks which will have to coexist, albeit temporarily, with new mobile networks in a situation of mutual interference. The analysis carried out so far aims at highlighting possible criticalities, in case separation between networks is not sufficient to ensure the proper functioning of the different systems.