Following the successful launch of 5G Non Standalone (NSA), mobile service providers are now focusing on Standalone (SA) 5G.
A key part of their future roadmap to support ultra-low latency and very high bit-rate applications depends on the availability of large amounts of 5G radio spectrum. This can be achieved initially by reframing a portion of their existing 2G, 3G or 4G spectrum holdings although much of this spectrum is still required to continue to support these legacy networks. However, to truly bring about widespread coverage and capacity, mobile service providers need to acquire the new radio spectrum recently identified by the ITU (International Telecommunication Union) WRC-19 (World Radio Conference – 2019).
Radio Spectrum in Release 16
Currently, as part of 3GPP Release 16, there are two defined “Frequency Ranges”. The lower range is known as Frequency Range 1 (FR1) and defines 45 operating bands between 410MHz to 7125MHz. In contrast, Frequency Range 2 (FR2) is typically termed mmWave (Millimetre Wave) and defines 4 operating bands in the 24.25GHz to 52.6GHz range. The majority of these Release 16 bands were identified as far back as 2015 during WRC-15.
It’s worth noting that the defined operating bands for FR1 and FR2 don’t occupy all the frequencies defined within the ranges, i.e. there are gaps. In addition, some of the operating bands are not globally harmonized.
During my many deliveries of 5G Air Interface related courses, the focus has been on 5G NSA (Non Standalone) deployments, typically utilizing Band N78 (3.3GHz to 3.8GHz). However, whilst this provides a “boost” to 4G data services it does not facilitate the very high bit rates which 5G can provide. In most networks I’ve worked with, this “bolting on” of 5G provides up to ~300Mbps on top of the typical 4G data service. This effectively offloads the data from 4G to 5G (for 5G enabled users) and thus improves the 4G experience for 4G only devices. To get 5G ultra-high data rates, service providers need more spectrum.
WRC-19 for 5G
A key requirement for the success of 5G is the availability of radio spectrum, which includes both new spectrum in addition to the global harmonization of existing spectrum. Prior to WRC-19 several 5G candidate bands were submitted for inclusion. Unfortunately, not all candidate bands were successful, however the conference was still seen as a great success for 5G – since a total of 17.25GHz of spectrum was agreed upon, of which 14.75GHz is globally harmonized.
The most common reason for not allocating all of the proposed 5G candidate bands relates to WRC-19’s responsibly for protecting existing radio systems such as Earth Exploration Satellite Services which are primarily used by the world’s meteorological organizations.
The newly identified radio spectrum (66GHz to 71GHz) will necessitate changes to the 3GPP’s specification for the FR2, since it falls outside the current FR2 limits (24.25GHz to 52.6GHz). As such this will be seen in later releases of the specifications.
We are all looking forward to service providers gaining access to more mmWave allocations. Granted, there will be many challenges related to cell sites, small cells, backhaul and transmission, propagation characteristics etc. As a comparison, in some of the trials I’ve been working on, a 100MHz channel of FR2 can provide data rates of up to ~1Gbps, which I suspect may be challenging for the backhaul designers!
Many countries still do not have access to specific FR1 and FR2 bands since they may not be globally harmonized for them. As such, WRC-19 focused on the global harmonization of mmWave bands and during the conference, it managed to achieve this for a number of bands as illustrated in Figure 3. However, the newly identified 5G radio frequency bands of 45.4GHz to 47GHz and 47.2GHz to 48.2GHz were unfortunately not globally harmonized as part of WRC-19.
As the dust begins to settle on WRC-19, numerous organizations are already looking forward to WRC-23 where the focus looks to be related to providing high coverage for 5G. That is below 1GHz, as well as additional higher frequencies and a greater emphasis on global harmonization. For more information on the future of 5G spectrum, it is worth visiting the GSMA (GSM Association).