T-Mobile has been equally hyperactive in 5G roll-out and associated marketing as it attempts to make full use of the window of opportunity presented by a temporarily big lead in midband deployment. Having made significant gains in urban areas it is now taking the fight into the country, which – counting small rural towns in a nation with relatively few villages – amounted to 130m people, almost 40% of the 328m total.
Furthermore, it is a population that has been underserved by both fixed and mobile broadband from the outset, noting that rural lag in broadband has posed a conundrum for governments, regulators and operators alike the world over.
In the rural context then, T-Mobile’s campaign is more interesting for what it says about 5G’s potential at last to reduce the digital deficit than its own competitive battles. A digital divide of some sort is not cast in stone but has seemed an enduring economic reality for both fixed and mobile. In a sparser population greater distances from the nearest DSLAM in the case of fixed or base station for mobile seem inevitable, so given signal degradation with distance some depletion in bandwidth is hard to avoid without excessive subsidy. In the case of fixed, only running fiber to every home can ultimately fix the digital deficit and that incurs greater physical cost of cabling in rural areas, whatever approach is taken.
Mobile communications at first sight appears to suffer from a greater broadband deficit, given the presence of black spots in locations such as deep hollows, and also the ever-shorter range at the more capacious higher frequencies. It has seemed inevitable that mobile operators deploy macro cells to provide coverage for large areas that sacrifice speed for coverage. The cost of spectrum and lack of it for emerging local players has further damaged the case for adequate investment in rural mobile capacity.
Yet with appropriate incentives coupled with technologies advancing under 5G, notably beamforming and Massive MIMO, there is rising hope that mobile services can fill in with adequate performance where fixed services of equivalent quality can never be delivered economically. MIMO has been in operation longest in smaller configurations, having evolved for WiFi as well as LTE, to boost capacity by operating multiple antennas in parallel. Beamforming, although with roots going back to 2G, has only really come to the fore in 5G because it is necessary for those more dynamic and high performance requirements. Indeed, without beamforming waiting in the wings, the full expanse of 5G use cases would not have been possible, as it enables that vital capability dubbed ‘fiber without wire’ by focusing signal energy accurately and tightly.
Beamforming can be applied in principle to any waveform, combining orientation of multiple antennas with manipulation of amplitude as well as phase to ensure that target points receive positively interfering waves from multiple points. The focusing of signals reduces interference for devices not in the path, as well as increasing the bandwidth for the target. At the same time, the number of antenna elements that can supported at a base station has increased under 5G compared with LTE, rising to 512 or even more in future. In this regard, higher millimeter wave frequencies confer an advantage, because while signal propagation through the air is increased, the size of antenna reduces in line with the wavelength. Furthermore, progress in antenna design has brought scope for more flexible orientation, so that beams can be tilted in two dimensions across both the horizontal and vertical planes.
Of course, this requires more sophisticated signal processing to achieve and base stations supporting Massive MIMO with beamforming must incorporate algorithms capable of ensuring sufficiently accurate computation of amplitude and phase to ensure that destructive interference is eliminated around the target area. Algorithmic complexity increases rapidly with numbers of users and antennae, this being the major constraint over scalability of Massive MIMO and beamforming.
Nonetheless, rapid progress has been made with significant benefits for rural 5G, targeting individual customers through fixed wireless access (FWA) and for backhaul instead of fiber or traditional microwave. This is particularly appealing for areas that are relatively flat where signals can be propagated widely over distances of several kilometers. The Australian Outback is a perfect example, comprising a large area with a total of around 620,000 premises, 90% of which are already reachable by beamforming antennas. The tested range is up to 7.3km, over which national broadband wholesaler NBN has demonstrated transmission at 1Gbps with partners Ericsson, Qualcomm and Casa Systems, using mmWave spectrum with beamforming.
Back in the USA, T-Mobile is also promoting FWA for rural customers, but currently over midband rather than mmWave. In April 2021, the operator launched its 5G FWA service in every US state except Alaska, as a sequel to its LTE FWA pilot with 20m households in 450 towns in October 2020. The target was, initially, subscribers cut off by AT&T’s discontinuation of DSL home broadband, but now includes ongoing rural subscribers of fixed broadband services as well with an offering costing $60 per month and access to 5G where available, reaching 30m households.
The latest marketing assault, though, also encompasses traditional mobile, with T-Mobile aiming to deliver complete broadband packages including roaming as well as home access. It is really a tactical move to mop up as many customers as possible before Verizon and AT&T get going with the 3.7-4.2 GHz C-band spectrum acquired in the world’s most expensive auction so far, concluding early 2021 and raising $81bn.
T-Mobile has to tread a delicate balancing act here to avoid being accused of hypocrisy, having acquired some C-band spectrum itself in that auction. It is true that its holding is relatively small at around 10% of the total, Verizon having over half after spending $45.5bn in a desperate attempt to catch up in terms of total holdings for 5G. Even after that, Verizon still lags behind T-Mobile in overall spectrum ownership below 6 GHz, although it is well ahead in the mmWave.
The point here is that a large proportion of Verizon’s C-band winnings are in the A Block, becoming commercially available by the end of 2021, while T-Mobile’s are in the B and C Blocks, which will not be active until around 2023. This discrepancy in timing reflects concessions to satellite platforms, giving them time to move services clear of that spectrum.
At least that gave T-Mobile CEO Mike Sievert room to express his nuanced view of the C-band from the rural 5G perspective. “If you have to build out a C-Band network to match a 2.5 GHz built midband network, you’re looking at probably up to a 50% increase in density,” he said. “Don’t get me wrong, we spent a lot of money on C-band. We’ll be deploying that to supplement on top of a great 2.5 GHz layer. But it’s hard to believe that you’re going to be able to, with the density and the numbers that have been talked about by our competition … compete with the footprint and the breadth of coverage that T-Mobile is going to provide on 5G.”
Meanwhile, Sievert admitted that T-Mobile was involved in a mad dash to exploit this window of opportunity ahead of C-band deployment, especially to plug rural coverage gaps. More widely, rural coverage will be a big focus of 5G and with the help of beamforming there are hopes that the digital deficit can be reduced, even though it can never be eliminated entirely.