The idea of a rule-based approach to spectrum management was a recurring topic at the WCA’s Spectrum 2020 event. Although the theme of this year’s panel was unlicensed wireless, much of the focus was on an innovative approach to spectrum management that relies on rules and machines to dynamically harmonize the usage and ensure maximum utilization of spectrum.
It was an honor to moderate this panel, which delved into the topic of unlicensed and lightly licensed spectrum. The WCA put together an outstanding group of panelists who are knowledgeable in all aspects of wireless policy, technology, and deployment.
The timing of this panel couldn’t have been better with Monday’s FCC announcement of the commercialization of the CBRS band (3550-3700 MHz) and the almost simultaneous release of NTIA’s study on the 3450-3550 band and how it might be shared with incumbents.
Richard Bernhardt, the National Spectrum Advisor for WISPA, explained that CBRS is technology-neutral within prescribed rules and management of the Spectrum Access System (SAS) administrators. Bernhardt and Google’s Andrew Clegg pointed out that an amazing thing about CBRS is that, even though it only launched on Monday, it is commercially available today with thousands of base stations already operational. Bernhardt and Clegg are part of the Wireless Innovation Forum, an international group of organizations advancing the innovative use of spectrum, such as the new CBRS standards.
As a proof-point of CBRS’ availability, ahead of tomorrow’s Superbowl, Quantum Wireless just announced their deployment of a CBRS distributed antenna system (DAS) inside the Faena Miami Beach luxury resort. As a neutral host, Quantum will carry traffic within the resort for the nation’s two largest carriers. Guests who are subscribers to those carriers and with OnGo certified handsets (e.g. iPhone 11, Google Pixel 4, etc.) and endpoints will be able to connect to Quantum Wireless’s CBRS private network.
The neutral host approach, which Quantum Wireless represents, is just one business model that CBRS enables. Using CBRS for private networks or as extensions to existing telecom networks (e.g.as a wireless last-mile extension for a rural fiber telecom network) are other CBRS business models. The CBRS Alliance sees use-cases bucketed into three broad categories of in-building, public spaces and industrial IoT.
The CBRS band is technology neutral (e.g. devices can use whatever modulation they want), as well as licensed by rule. This innovative approach to spectrum management provides deployment flexibility, lower cost and faster market entry than traditional licensed approaches while mitigating potential interference issues of a pure unlicensed approach.
As Google’s Andy Clegg indicated, the Spectrum Access System is the magic glue that manages CBRS and ensures that there is no interference between the different types of licensees. The SAS is a database that knows the location of and the power levels of each of the CBRS base stations, ensure that the base stations do not interfere with each other and adjudicates between different license uses. As is done with TV White Spaces (TVWS), the SAS administrators are FCC-approved entities; four of which (CommScope, Federated Wireless, Google, and Sony P(DF)), were approved on Monday, with another six in the application process.
There are three types of licenses; Incumbent, PAL (Priority Access License) and GAA (General Authorized Access). The Tier 1 licensees are the incumbents, which include the Department of Defense and grandfathered Fixed Satellite Service (FSS), while grandfathered wireless broadband wireless operators, such as described in this video interview, must migrate to CBRS between 2020 to 2023.
The Tier 2 licensees, are called Priority Access Licenses (PAL), are 10 MHz chunks of bandwidth, between 3550 and 3,650 MHz that will be auctioned (Auction 105 PDF) beginning June 25th on a county-by-county, 10-year, renewable basis. Up to seven of these channels will be available in each county and one entity may only aggregate up to four licenses per county. The PAL licenses are subordinate to the Tier 1 licensees.
The General Authorized Access is available for any entity to use, but they must cede to the higher priority Tier 1 and Tier 2 licenses. What makes the CBRS approach unique is that just because a PAL has a county-wide license for a given channel, a GAA licensee may use that channel in a part of the same county that the PAL does not serve. Of course, the GAA does this at the risk that a PAL licensee might someday serve that area, which would mean they would no longer be able to use that channel.
The CBRS approach may solve the problem of fallow spectrum whereby, in the past, a large operator that is focused on dense areas fails to build out or makes rural areas its lowest priority. The GAA alternative gives local entities the opportunity to build out rural areas without having to bid on a larger geographic area for spectrum.
As the auction unfolds, it will be interesting to see the bets that entities will make on Priority Access Licenses. For instance, in extremely rural areas will it make more sense to not bid and gamble on the effectiveness of a GAA license?
And, could there be a potential near-term glut of spectrum that might deflate the value of the June auction. Some of that spectrum could include 3100-3550 MHz (NTIA is studying how this spectrum could be used by industry thanks to the RAY BAUM act), the potential for additional spectrum in the 3700-4200 MHz range, the potential release of DSRC (5850-5895 MHz) and the 6 GHz band (5925-7125) more on that below).
Another thing that makes CBRS important, as Kelly Drye’s Chip Yorkgitis stated in his presentation, is that it may prove the model for other sharing mechanisms, as new spectrum is cleared for commercial use. CBRS’s influence may be felt as soon as the first half of 2020, as that is when the FCC is expected to complete its Report and Order on 6 GHz (Docket 18-295).
Like CBRS, this band looks like it will have a spectrum management mechanism, called AFC (Automatic Frequency Coordination) to adjudicate between users and uses (indoor/outdoor, power levels). Aruba’s Chuck Lukaszewski indicated one of the potential advantages of this block of spectrum is that, under the plan championed by the Wi-Fi industry, this band could support seven each, 160 MHz channels providing an unprecedented amount of data throughput.
As of the publication of this article, there are 475 filings to the FCC on the 6 GHz docket, with input coming from entities as diverse as the NFL, the NAB, and Apple. As such, the FCC will face the challenge of balancing the existing investments and concerns of spectrum incumbents, with the potential for direct revenue from traditional auctions, with the promise of innovation and secondary economic impact that comes with new technologies in a lightly licensed approach.
Although we didn’t discuss it in the meeting, the potential economic impact from unlicensed and lightly licensed can be quite large, as a recent RAND study (funded by the Comcast Innovation Fund) recently suggested the unlicensed use of the 5850-5925 MHz band could provide total gains to economic welfare in the form of consumer and producer surplus ranging from $82.2 billion to $189.9 billion.
Speaking of gobs of spectrum, Mark Jen of Common Networks explained how they are using spectrum in the 60 GHz band (802.11ad/WiGig) to offer high-speed, unlicensed wireless broadband to customers in parts of the Bay Area. Common Networks is a service company with deeply integrated technology roots that include designing their own equipment. The issue to date has been needing Line of Sight (LoS) from the customer to base station.
To get around LoS issues, Common Networks is looking to begin deployment of 802.11ay equipment by the second half of 2020. This is the same technology championed by Facebook with its Terragraph project. It uses a TDMA (Time Division Multiple Access) Mac for predictable latency, a high degree of frequency reuse and it enables an outdoor multi-hop wireless network so that LoS back to a tower is not necessary. Although fiber is still needed for backhaul, Jen pointed out that this mesh approach is much faster to deploy than a small cell approach.
With such knowledgeable subject matter experts and an equally sophisticated audience, the question and answer session was extremely interactive. My notes and questions, many of which will need to be addressed at a future time, weren’t needed as there was a great rapport between audience and panel and much interest in the topic of the evening.
With that said, I am remiss that I didn’t mention one of the quotes I had found in preparation for the panel, as the originator of that quote, Wi-NOW’s Claus Hetting was in the audience. This quote, repeated by FCC Chair Pai at a September 24th, 2019 National Press Club event, captures the excitement surrounding unlicensed and lightly licensed spectrum,
“This (6 GHz) is without a doubt the single biggest opportunity in Wi-Fi – and probably in wireless – in a generation,” adding that, “this 6 GHz spectrum boost will launch the Wi-Fi industry in a new growth trajectory.”