CBRS - Private LTE Networks For IoT Applications

If you are contemplating an IoT deployment in the near future, you should start paying attention to an emerging LTE communications standard called CBRS - the Citizens Broadband Radio Service.

CBRS, or Band 48 as it's known within the community, is 150 Mhz of prime RF real estate between 3.55Ghz and 3.7Ghz recently made available by the US Government with a novel three-tiered approach to sharing. It could set the stage for affordable, high-performance indoor and outdoor private LTE networks, ones not owned by the cellular carriers, without the prohibitive cost associated with purchasing spectrum.

It's been labeled as the “great experiment” by the FCC and, if successful, could pave the way for more efficient use of all spectrum in the future – driving technical innovation and enabling new business models.

To bring you the latest developments, IoT For All attended the first of a packed three-day CBRS Alliance meeting hosted by Qualcomm in San Diego on August 1. Before diving into the details of that meeting, a little background on CBRS is necessary for context. If you already have a good grasp on the technology, just skip down a few paragraphs to get the highlights from the meeting.

Citizens Broadband Radio Service (CBRS)

The CBRS sharing concept has three tiers.

1. Incumbent users such as the Department of Defense have prioritized access to the band at any time, although their use is coordinated in a way that minimizes impacts to commercial users through a network of Environmental Sensing Capabilities (ESCs) and Spectrum Access Systems (SASs). Due to the band’s propagation characteristics, the potential disruption is really only a concern along the coasts where the US Navy operates from time-to-time.
2. Private Access Licenses (PALs) can be leased by anyone in 10Mhz increments for terms of between 3-6 years and are restricted geographically to enable local implementations. They provide guaranteed access to spectrum for enhanced QoS applications and will be auctioned in a similar manner as licensed spectrum – although at a greatly reduced cost.
3. General Authorized Access (GAA) is the bottom tier of CBRS and provides free access to anyone - much like unlicensed spectrum does today but in a much cleaner RF environment since it doesn’t suffer from the high levels of congestion associated with Wifi in the 2.4GHz and 5GHz bands.

If you want a more in-depth look at CBRS, you can read What is CBRS? - LTE in the 3.5 GHz Shared Spectrum and What it Means for IoT. Now back to the meeting.

Key Takeaways from CBRS Alliance Meeting

FCC Commissioner Michael O’Reilly kicked off the day’s activities with an information-packed keynote describing the FCC’s commitment to CBRS and the efforts currently underway to finalize the standard.

Key parameters that are still being tweaked generally only relate to PALs and include longer license terms for licensees (from the current 3-6 years to perhaps 5-10 years), larger geographical areas for licensees (municipalities or business economic zones rather than much smaller census tracts), and better clarity around PAL license renewal policies. \

Reading between the lines, I expect portions of the standard to be finalized and approved within the next few months with official GAA-only implementations rolling out by the beginning of 2018. The details of PAL are likely to take a bit longer with auctions expected in Q2/Q3 2018.

It is possible, although unlikely, that PAL may not even make the final cut and CBRS will be released with only incumbent DoD and GAA support. The key driver to real deployments from the FCC’s perspective is the availability of certified ESCs to avoid interference with US Navy operations along the coasts. Inland deployments may happen sooner if ESCs are delayed since interference is non-existent due to the short propagation attributes of the band.

Neville Meijers (Qualcomm, CBRS Chairman of the Board) and Preston Marshall (Alphabet Access, CBRS Vice Chairman) announced the creation of a public Business Working Group (BWG) that will focus on defining key Applications and feeding back those insights into the finalization of the technical specifications being established by the 3GPP.

There is no charge for participation in the BWG through the end of 2017 so it provides a great opportunity for industry players and end users to impact development of the standard and align it with business goals. If you are interested in participating in the working group, visit https://www.cbrsalliance.org for more details.

Cris Kimbrough, Managing Director of Telecom Services at CBRE, the world’s largest property management company with 3B square feet under management, provided her insights into the difficulties and costs associated with building-centric Wifi deployments, a.k.a. Distributed Antenna System (DAS). She stressed that affordable neutral-host offerings like CBRS, i.e., not tied to a particular cellular carrier, can provide tremendous value to tenants but it is important to understand the ROI and technical stability of these systems before widely deploying them.

There is also a marketing challenge since end users typically do not understand or are not interested in the technical details. They simply want a reliable, future-proof system that is easy to install and manage. That being said, if CBRS continues to gain momentum and industry-wide acceptance, it may provide an interesting (and much cheaper) alternative to building-based Wifi.

Perhaps the highlight of the all-day meeting was the live demonstrations of CBRS capabilities and equipment in the late afternoon. Vendors including Qualcomm, Commscope, Airspan, Ruckus Wireless, Nokia, Accelleran, Juni, and Federated Wireless displayed a variety of CBRS equipment including gateways, early SAS implementations, and even an ESC.

Although there is still work to be done, it was clear that major players in the industry are investing heavily in CBRS now and that pilots are possible for those companies looking to get early mover advantage.

In summary, if you’ve been considering cellular-based LTE or Wifi as the communications backbone for certain high-bandwidth, low latency IoT Applications, you should check out CBRS. It might be just what you’re looking for.

Note: T-Mobile has submitted a proposal to virtually eliminate unlicensed use of the spectrum, thereby substantially raising the barrier to entry for businesses seeking to utilize the 3.5 GHz band. You can read more about the issue and how you can take action here.