Verizon and AT&T face significant engineering challenges to build on their initial, limited roll-outs of 5G in millimeter wave spectrum, and deliver broad coverage and high data rates given their lack of midband airwaves, which are ideal for first-phase 5G (see separate item on Russian MNOs).
The two companies have always invested large sums in their own technologies and architectures, so if anyone can make a powerful service platform at viable cost, with mmWave spectrum, these two are likely to do so. Some initial tactics have included advanced deployment of MIMO antennas and beamforming, as well as migration roadmaps to highly virtualized networks and to automation.
But making a high performance network that reaches users indoors as well as out, given the limited range and indoor penetration of mmWave, will require a whole host of technologies. Two of Verizon’s current plans include extended carrier aggregation, and a deal with Boingo Wireless to improve indoor coverage.
The telco has petitioned the FCC for permission to conduct further tests in the 3.5 GHz CBRS band, which is the only way for US operators to access the valuable midrange C-band. There are two tiers open to MNOs – priority access licences (PALs), which will be auctioned next year and could support 5G, but are likely to involve small territories and short licence terms; and general authorized access (GAA), a shared approach which will initially be restricted to 4G, at least until standards for 5G-Unlicensed are agreed.
Verizon says in its FCC filing that it wants to test TD-LTE transmissions on outdoor 3.5 GHz CBRS (3GPP Band 48) small cells, and to use “inter-band carrier aggregation” with other bands. This could be vital to harness 3.5 GHz while mitigating the effects of the limited quantities available to US operators under licence, and the risks of shared spectrum.
The telco wrote: “Some of the tests with mobile stations will be using CBRS spectrum only. The majority of the tests, however, will include mobile devices and base stations with LTE transmitters that operate on 3GPP Band 2, Band 4, Band 66 or Band 13, in carrier aggregation mode (in both downlink and uplink) with Band 48.” Those bands, in the 3GPP scheme of official spectrum options for its standards, equate to 1.9 GHz PCS
(Band 2), 1.7/2.1 GHz AWS (Bands 4 and 66) and 700 MHz (Band 13).
Verizon could use CBRS spectrum with carrier aggregation in two ways before 5G-Unlicensed standards emerge. It could use 4G in shared spectrum for supplemental downlink in LTE, in the same way as LTE-Licensed Assisted Access (LAA) in 5 GHz. Or it could use licensed bands to improve coverage when aggregated with mmWave airwaves, or to boost capacity when Verizon comes to deploy a 5G coverage layer, which will mean refarming some or all of its 700 MHz LTE spectrum, or acquiring other sub-GHz options (unlike T-Mobile USA, Verizon did not buy any spectrum in last year’s 600 MHz incentive auction).
AT&T is also actively seeking to harness 3.5 GHz and to shape regulations to suit its business model. The operator recently proposed that the FCC permit a higher level of power for a new, third category of 3.5 GHz devices, for 5G.
Initial commercial deployments in shared CBRS spectrum are expected from next month while the auctions will happen next year.
Meanwhile, Verizon has announced that it is working with Boingo Wireless, best known for large-scale public WiFi deployment and aggregation, to improve indoor 5G services in public spaces such as airports, stadiums, office buildings and hotels. Initially the aim will be to bring 5G to Boingo’s existing DAS (distributed antenna system) customer sites, and then there will be expansion opportunities for both partners.
The two companies are cooperating to architect a “hyperdense network designed for large and small indoor spaces”, using Boingo’s DAS platform – the WiFi offload business, another major source of US telco revenue for Boingo, is not involved.
In its DAS unit, Boingo runs the indoor network on behalf of a carrier, for a monthly fee, though no terms were disclosed in the new announcement.
Earlier this year, Boingo said it had deployed 10 new DAS networks in the second quarter in partnership with tier one US carriers in high traffic venues. That brought its DAS total to 69 locations.