Midband spectrum is widely recognized to be the sweet spot for 5G deployments globally, due to its combination of large amounts of available bandwidth and better propagation characteristics than millimeter-wave. In the past year, the U.S. Federal Communications Commission has auctioned the 70 megahertz of CBRS Priority Access Licenses, plus another 280 megahertz of C-Band spectrum that will begin coming online late this year and is teeing up 100 megahertz of additional midband spectrum at 3.45-3.55 GHz, just below the CBRS band, with the auction set to start October 5, 2021.
In total, that means that at the end of this year, the FCC will have opened up 530 megahertz of midband spectrum (auctioning 450 megahertz of it) and 250 megahertz will be available for use, with the rest coming online in the next few years. In the context of all that new spectrum, RCR Wireless News asked Ed Alfonso, head of mobile networks for the Americas at Nokia, about trends and activity in midband spectrum in the United States.
This Q&A was conducted via email and has been lightly edited for clarity and continuity.
RCR: How would you describe the level of momentum Nokia is seeing in midband deployments in the U.S., whether that be CBRS or preparation for C Band?
Alfonso: The mid-band momentum in the U.S. is very strong and growing. Most mobile carriers are either already building or preparing to build mid-band (2.5GHz, CBRS, C-Band) 5G networks in the near future. Nokia is actively participating in trials and commercial deployments with both CBRS and C-Band. See here and here for examples.
We are already seeing good traction for CBRS GAA for private wireless in industrial sites and strong sign of acceleration on CBRS PAL, for WAN private wireless networks (utility, U-telco, etc.) Thanks to CBRS, the U.S. market is very strong and represents a large share of the private wireless deployments globally.
RCR: How are you seeing CBRS being used? Primarily by carriers for capacity augmentation, for FWA or for private networks? Do you expect to see that mix change over time?
Alfonso: We are currently seeing all the above mentioned type of deployments for CBRS. The strategies can be different from carrier to carrier depending on their use cases and requirements. Some are more focused on capacity, some FWA and some on private networks. The carriers who own C Band, may prioritise the deployment of this band over CBRS as the higher power provides improved coverage and capacity.
RCR: How do you think that C Band deployments will change 5G in the U.S.? In what timeframe (2022? ’23? Beyond?)
Alfonso: The C-band deployment in the U.S. is crucial for 5G capacity and coverage going forward. While low-band FDD frequencies provide good coverage and mmWave frequencies provide massive hot spot capacity, C-band (and mid-band frequencies in general) hit the sweet spot between both capacity and coverage. Commercial network deployments have already started and wide scale availability is expected for 2022 onwards.
RCR: What will midband indoor infrastructure needs look like? Will it need dedicated systems or will it provide sufficient coverage outdoor-in?
Alfonso: For indoor coverage, there will be both outdoor-in and dedicated indoor solutions. Nokia’s comprehensive C-Band portfolio, which covers both indoor and outdoor deployment needs, includes massive MIMO antenna solutions, hybrid antennas that combine both passive and active radio platforms into a single, modular unit, macro remote radio heads and small cell solutions to cover all connectivity and deployment requirements. When new spectrum is auctioned and acquired by carriers, the initial focus is typically on the macro layer to provide wide area coverage, and then it starts to shift focus to different scenarios like in-building.
RCR: In LTE, as the technology evolved and more people made use of it, carriers had to make a massive effort to upgrade backhaul capacity, and they also had to deal with issues like PIM in the lower bands. Do you see any similar challenges ahead for 5G and midband spectrum? Or has the industry learned lessons from 4G that they’re applying now?
Alfonso: In anticipation of 5G, many carriers started upgrading their fronthaul and backhaul transport capacity some years back, many with fiber. This is an ongoing effort as RAN capacity is consistently being added as the subscriber data usage keeps growing. CBRS spectrum has it’s unique characteristics and planning challenges with limitations on maximum output power and spectrum sharing coordinated by the Spectrum Access System administrators.
RCR: Are there any particularly interesting midband trials that Nokia has participated in that you can talk about?
Alfonso: We have participated and are currently participating in several CBRS and C-Band testing and trialing activities in the U.S. One of the latest published ones is with AT&T, where Nokia was the first vendor to successfully complete a 5G trial in C-Band spectrum in the U.S, using its commercial 5G AirScale portfolio.
RCR: Verizon recently asked for permission from the FCC to tune its C Band deployment model. Shared CBRS spectrum is still somewhat of a novelty and has only been fully licensed for a relatively short time. What are the details of midband spectrum behavior that operators and equipment OEMs still need to understand to rapidly and efficiently plan and deploy these networks?
Alfonso: We believe that the U.S. carriers are well positioned to deploy mid-band 5G networks. What remains important is the clearing of the initial C-band spectrum by December 2021 and to meet the full clearing requirements throughout U.S. by December 2023. In addition CBRS spectrum has its unique characteristics and planning challenges with limitations on power and spectrum sharing coordinated by the Spectrum Access System administrators.
RCR: What other emerging technologies (Open RAN, vRAN, MEC, etc.) are also emerging that you think will impact how midband spectrum is deployed in the US?
Alfonso: The new technologies like ORAN, vRAN, RIC and MEC will shape the industry going forward, but are not tied to mid-band deployments. The majority of operators deploying mid-band spectrum will leverage existing architecture and continue to trial and evaluate emerging technologies. Other technologies that have potential for carriers to deploy and operate networks more efficiently include the use of AI/ML in applications like massive MIMO beamforming pattern optimization, smart energy saving features and traffic steering.
Nokia´s first generation 5G AirScale Cloud RAN vRAN1.0, with virtualized Centralized Unit has been deployed and is carrying commercial traffic since mid-2019 in a large scale deployment, representing the world´s first commercial cloud-based 5G RAN and Nokia´s AirScale Cloud RAN vRAN2.0, with both virtualized Centralized Unit and virtualized Distributed Unit, is in trials with commercial deployments starting in 2022.
Looking for more insights on the midband spectrum landscape? Check out the RCR Wireless News webinar featuring Aurora Insight, Analog Devices and LitePoint, and download our editorial report: Minding the Midband: Trends, momentum and deployment in the U.S.