Adding more spectrum and more cell sites can help operators overcome the deficit
Consumer data demand is skyrocketing and is only expected to keep increasing in a 5G world. Spectrum to meet this demand, however, is not growing exponentially, giving rise to a significant potential for a deficit of nearly 1 GHz in the amount of spectrum available for growing mobile data services (see Figure 1). Mobile operators need to manage this deficit to make the most of their spectrum investment, maintain their service levels and support new services in a 5G world.
In mid-January 2021, 280MHz was added to the available spectrum pool through an FCC auction that garnered more than $80 billion from mobile operators. Other countries around the world have or are holding their own auctions. Yet, in the U.S. according to our model, growing demand for data services threatens operators with the possibility that data demand will overwhelm the available spectrum starting in 2021 and continuing to get worse through 2025. At its worst point, the deficit could total 963 MHz more to deliver service as currently planned.
The model updates an FCC Staff Technical paper first published in Oct. 2010 that measures growth in data demand, available spectrum, spectral efficiency, number of cell sites and other factors (see original FCC paper here (PDF download); updated whitepaper can be found here).
This analysis is based on 4G data services and doesn’t factor in growing 5G services that will require ever larger swaths of spectrum to fuel high-bandwidth applications. Given the amount of money spent on spectrum, ensuring that it is not wasted is an important consideration. In this model, we estimate that more than $1B of spectrum in the U.S. alone could be wasted due to interference if it degrades spectral efficiency by as little as 1%.
The solutions to a spectrum deficit
Adding more spectrum and more cell sites can help operators overcome the deficit by adding more capacity to the network, but both are capital intensive.
Another strategy for operators is to manage spectral efficiency in order to make the most of what they have licensed. Managing spectral efficiency means identifying where spectrum is being wasted and applying techniques to improve efficiency and also to utilize unlicensed spectrum to offload demand.
Spectral efficiency defines how effective a given frequency carries a packet of data (bits per second per Hertz). Spectral efficiency is dependent upon new radio technologies that are defined by 3GPP and other standards bodies.
Technologies that can improve spectral efficiency include better RF filters, mMIMO and a more scalable frequency structure to optimize “packing” into the available spectrum. These technologies improve spectral efficiency by enabling the processing of significantly wider bandwidths through the same infrastructure, reducing the cost for deployment by the MNO.
More specifically, operators should look at:
RF Filters: Many of the new spectrum bands have wide bandwidths needed for advanced services. Just as in 4G networks, RF filters need new resonator breakthroughs to support the wide bandwidth (>500 MHz and up to 2000 MHz), high frequency (>3GHz), high power (30 dBm; 1 Watt) and low loss needed for the wireless operator to deliver high-speed data services at full bandwidth with minimal losses. And with increasing use of the 5G and Wi-Fi, which have adjacent frequency bands, filters will need to mitigate a growing interference problem that degrades the user experience.
mMIMO: These antenna systems feature dozens, up to 100, antennas at a given basestation. Multiple antennas to be combined to form directed high-bandwidth beams using space division multiple access (SDMA) which can track mobile devices and optimize the mMIMO beam to provide optimized transmission and reception for each user device in the cell. This improves spectral efficiency by reducing the wasted power from a base station that radiates its signal in all directions without an understanding of where devices are located.
Unlicensed Spectrum: Building access to unlicensed spectrum, such as Wi-Fi, into mobile devices provides a new source of bandwidth for mobile operators. When users are on a secure and high-bandwidth Wi-Fi connection, mobile operators are able to offload traffic from their network. But there are downsides to unlicensed spectrum, ranging from reduced revenue and unmanaged infrastructure. This has made mobile operators reluctant to utilize this spectrum in the past. That needs to change to combat the deficit spectrum, as using unlicensed spectrum has the most potential for making up the deficit. The 5G standards body has recognized the need for unlicensed spectrum with the 5G new radio unlicensed (5G-NR-U) standard that enables the implementation of 5G on unlicensed spectrum, opening up access to significantly more spectrum both in the US and other parts of the world.
Conclusion
Spectrum is the critical success factor in wireless networks especially in 5G networks where more spectrum is required to offer promised new services from broadband internet access, to extended reality and autonomous driving services. But spectrum is expensive and with a deficit on the way, mobile operators need to add spectral efficiency methods to their infrastructure plans.
