Spectrum sharing is fundamental to 5G plans. Sometimes this is a way to open up a virgin band to multiple users, on an increasingly dynamic basis, in order to enable a far greater diversity of service providres in the 5G era, in line with the need to support many more industries and applications.
Often it is a more defensive technology, aiming to extend the number of operators which can use an occupied band, while protecting the incumbent from interference – potentially a fairer, simpler and less politically contentious approach than pushing organizations out of prime cellular bands altogether.
The most famous examples have been pioneered in the USA, especially the TV white spaces (TVWS) sharing scheme, which despite limited commercial impact established the groundwork for the emerging CBRS plan in the 3.5 GHz band, with its three levels of access from fully protected through licensed to shared.
The USA has a particularly urgent requirement because there are federal incumbents in the 3.5 GHz band, which in most other regions is the primary first-wave band for early 5G. The fact that 3.5 GHz is not vacant in the USA has driven the country’s high level of interest in mmWave to add 5G capacity, but also justified the hefty amount of development and political argument that has gone into creating the CBRS framework.
But other regions are developing similar approaches to address their own need for more cellular spectrum, not just for MNOs but for new operators. And the standards bodies will be looking to create global specifications to ensure sharing schemes do not become fragmented in different parts of the world, which would, in turn, create roaming issues and reduce economies of scale for chipset and device makers.
One of the promising developments has been under way for some years at standards body ETSI, which has defined Licensed Shared Access (LSA), with its initial target being the frequencies in which radio microphones are incumbent. Radio mics are essential to the live entertainment industry, which is in a growth phase, unlike recorded content. But this sector is concerned about plans by European regulators to extend the ‘digital dividend’ spectrum – the 800 MHz band, opened up for LTE by the transition to digital TV – down to the 700 MHz band.
That process has been agreed with the broadcast sector, but when the 700 MHz spectrum is cleared for 5G over the next few years, the radio mics will lose a lot of their spectrum. In the UK, for example, the Programme Making and Special Events (PMSE) band will be greatly reduced, and its microphones will end up with just the guard band in 694 MHz to 703 MHz from May 1 2020. Other European countries are operating on similar deadlines to clear the band for 5G and a few, notably Germany, have already auctioned the spectrum in advance.
ETSI claims to have one of the best solutions to enable the services to coexist effectively. Last month, it announced that its LSA specs have been successfully implemented in The Netherlands after a decision to support them in the 2-3-2.4 GHz band, by the regulator, Radiocommunications Agency Netherlands. The two LSA specs (ETSI TS 103 235 and ETSI TS 103 379) are designed to negotiate spectrum access among multiple services. In The Netherlands, it has been implemented for cordless cameras and portable video links usded in programming and broadcasting special events. The regulater aims to add other services such as amateur radio and some government applications. It is also evaluating LSA in additional frequency bands such as 700 MHz, and for additional PMSE use cases which might be in these bands, including professional radio microphones, cordless audio distribution, foldback and talkback systems.