There are several organisations involved in the formal approval process.
- the Wireless Innovation Forum (usually shortened to WInnForum) who have developed and published the 10 baseline specifications for commercial operation
- CBRS Alliance, who promote and market commercialisation of the system. They’ve launched the brand OnGo and arranged a certification program.
- Federal Communication Commission, the regulator who defines policy, writes the rules and formally approves equipment for commercial operation.
- Department of Defense, actively using some of this spectrum for naval radar, and so has a veto over the rules adopted.
Additionally, there are equipment vendors, installers, managed services and others in the wider ecosystem.
The WINNForum publishes this useful status summary page, clearly segmented and with some cautious wording of the timescales. The phrase “not before” is used to avoid making unrealistic promises.
The 10 baseline standards are published and all in place. The different components of the solution each need to be certified and approved before commercial launch. Live outdoor trials have been ongoing for many months with individual test licences.
Spectrum Access Servers
Spectrum Access Systems (SAS) are the new and unique part of the CBRS concept, determining exactly which frequencies and power levels each small cell can operate. At this stage, the basic functionality must all conform to the same standards and interfaces – the vendors will differentiate themselves in other ways.
Mark Gibson of CommScope, recently elected as a CBRS Alliance Board Member, told me that the test scripts for SAS have been written and passed to the test labs. They now have 60 days to review and approve them. Formal Conformance Testing should then be able to start in early August and will likely take around 3 months. The FCC also would like a public trial period and is expected to publish a formal notice about this process later in June. All of the major SAS vendors have already run and passed these tests in-house, so there is a high level of confidence that it’s more of a paperwork than a technical development.
The government laboratory that conducts the tests (Institute for Telecommunication Sciences, ITS) will then pass their reports onto the FCC and DoD (Department of Defense). The FCC may give some indication of how long they might take to confirm that the tests have been successful. The DoD could be a bit more unpredictable.
In order to expedite progress, a limited commercial launch of CBRS service may be allowed during Q4 (after the tests have been passed). This would be based on GAA (General Authorized Access) mode and may be limited to lower RF power (Class A rather than Class B) in some areas.
- Category A (Indoor or Outdoor lower than 6m) Max EiRP – 30dBm @ 10MHz channel
- Category B (Outdoor only, professionally installed) Max EiRP – 47dBm @ 10MHz channel
There were originally seven conditionally-approved SAS Administrators awaiting certification:
- Federated Wireless
CTIA dropped out in 2017.
Environmental Sensing Capability
The Category B higher power option for CBRS, primarily for use outdoors, requires the Environmental Sensing Capability (ESC) to be in place to ensure that interference with DoD spectrum users is not allowed. Some SAS vendors have told me that they have already deployed hundreds of sensors so will be ready to turn them on immediately. Others are holding back their investment until lab testing and approval is complete.
Of the six active SAS vendors, only four will be deploying their own ESC. The others will have to buy this as a service from one of the others.
CBRS Small Cells
The acronym CBSD (CBRS Device) is used for CBRS compatible small cells. Fundamentally these could be almost any RF technology, including WiMAX, LTE or a proprietary method. In practice, I’d expect the vast majority will be standard LTE small cells adapted to operate in the 3.5GHz band using spectrum and RF power settings configured from one of the SAS servers.
Many vendors have demonstrated prototypes and conducted live trials – there should be no shortage of choice.
Certification is available today and should typically take a couple of weeks. Two approved labs are listed, one in the US and another in Taiwan. Some vendors are holding off pending the regulatory decisions, wanting to validate sufficient market demand before making further investments.
One nuance is whether freshly installed CBRS Small Cells could be permitted to make a brief transmission over the air in order to get their spectrum allocation. These so-called CPE CBSDs would be used where there isn’t an alternative backhaul in place. It opens up further possibilities for remote, private LTE networks.
The more powerfuel Cat. B CBRS deployments and any CBRS Small Cells without built-in GPS receivers are required to be installed by a certified professional installer (CPI). The WInnForum has begun a certified training and testing program. Nobody is yet listed as being approved, but this shouldn’t take too long to put in place.
Lower power Cat. A CBRS small cells with built-in GPS receivers will not need to be professionally installed.
Smartphones and Dongles
The first end user equipment is likely to be a combination of USB dongles and dedicated fixed wireless receivers. Both are involved in trials today.
Compatible smartphones are a little further off. Handset vendors have many competing features to prioritise between, but once the regulatory hurdles are passed and momentum builds we should expect to see these appear no earlier than mid-2019.
The other components required for a Private LTE network include some form of core network, primarily the EPC (Evolved Packet Core) and HSS (Home Subscriber Server). Subscriber administration, billing and even customer care may also be required. How handsets from operators are configured to behave when they encounter these neutral host networks and the level of intervention required by the handset owner to connect to them are not clear yet.
The CBRS Alliance announced this week a collaboration with ATIS, who oversee the assignment of IMSI numbers (unique SIM card identifiers). A detailed set of guidelines has been published on how this will be administered, making it both easy and efficient to be allocated with a range of IMSIs. These will be valid worldwide, where roaming agreements are in place, achieving another important milestone for Private LTE networks.
There are many potential vendors with software solutions of various sizes – we’ve reviewed potential EPC vendors recently in this article.
Although several large companies have announced plans to provide a neutral host service, this is a business segment still in its infancy. It’s an area which I’d expect the CBRS Alliance to develop further in the coming months. What will be needed is clarity to the various industry verticals about what they need to do, who they need to work with and what the business benefits will be.
Mark Gibson told me that the groundwork for CBRS has been done and we are moving into the final stages prior to commercial launch. While there’s a lot remaining to do and to come together over the next six months, it is quite realistic to expect commercial CBRS services to be in place before the year end.
Steve Plain, Amdocs Product Manager for CBRS, commented that the last six months has seen a significant increase in interest in its SAS Admin Service from many different types of organisations, confirming they can see the commercial potential of CBRS.
The regulatory hurdles remain the biggest potential roadblock. Many will be scrutinising the FCC”s July meeting and looking for clear direction. The most contentious aspect relates to the Priority Access Licences (PAL), with MNOs keen for larger tracts with longer licence periods. Independent building owners and local businesses may prefer to stick with the original proposal to allocate these by census tract, of which there are more than 80,000. A clear decision on this will fire the starting gun that triggers further investment.
Fortunately there’s no need to wait for PAL licences, initial GAA services can start in many areas just as soon as one of the SAS vendors is approved. Nationwide deployment can commence once ESC sensors are certified and deployed.
Next year, when a sufficient number of smartphones support this new frequency band, we could be looking back on quite an eventful period. Regulators in other countries will be watching progress carefully, with a view to adopting a similar approach if it is as successful as it promises to be.