What does 2022 have in store for microwave and mmWave technology?

A year ago I wrote that 2020 had been “a year of surprises”. I think few of us then anticipated that we would still be living with the pandemic at the start of 2022, but at PRFI we consider ourselves fortunate that its effects on our business have been both minimal and manageable.

What do we see as being the highlights of the coming year for the microwave design community? Here are three of my predictions:

  1. mmWave 5G will be led by the growth of broadband 5G Fixed Wireless Access (FWA) links direct to the premises

In the overall landscape of 5G connectivity, the mmWave bands currently carry very little of the traffic, with Opensignal[1] estimating that even phones equipped with mmWave 5G make use of it less than 1% of the time. In-building coverage is one of the biggest challenges, due to the difficulty in obtaining good indoor reception for high data-rate mmWave signals from an outdoor base station. I believe that the way to address this issue is to continue the roll-out of mmWave 5G FWA direct to the home or other premises, and to increase the deployment of mmWave 5G inside large buildings such as train stations and shopping malls.

With FWA, the mmWave radio transceiver is located outside the premises, with the users accessing the broadband capacity of the 5G cellular network typically via existing WiFi links, perhaps upgrading to WiFi 6 when this is available. The roll-out of FWA using mmWave 5G is growing, with leading player Verizon[1] announcing in early 2021 that it had reached 150,000 subscribers. Verizon’s subscribers were also seeing the fastest average mmWave 5G download speed, at 692.9 Mbps.

Developing the 5G FWA infrastructure will increase component volumes, reduce cost and allow the network operators to develop experience with mmWave subscriber links. Ultimately, I anticipate that mobile mmWave devices will switch seamlessly from the mmWave cellular network to an indoor network as the user enters a building, enabling the user’s broadband link will continue without interruption.

  1. The growth in broadband satellite communications will continue to accelerate

Satellite communications is an important and potentially very high-volume market for the components we design, requiring a solution that can be housed in an SMT package that is suitable for low-cost mass production and assembly. We are currently developing Ka-band GaN PA solutions for ground-based access equipment for broadband satcoms systems, as well as working with clients to develop high linearity, broadband PA components for phased array satellite communications systems operating at lower RF frequencies. These will be part of the satellite payload—each array will incorporate many channels and there will be a constellation of satellites, so it is still a high-volume application requiring careful consideration of unit cost as well as performance.

We have also recently been active in developing hardware for CubeSats, and some PRFI-designed equipment is currently deployed in space. These miniature satellites tend to have lower-volume requirements. The work we’ve undertaken has included both microwave power generation modules for innovative propulsion systems and mmWave PA modules, at around 40GHz, for comms links.

Looking to the future, we a have number of other ongoing enquiries components at Ka-band and above, which are all intended for broadband satellite communications systems. Satellite systems are certainly a booming market for PRFI at the moment.

  1. GaN technology will continue to erode LDMOS market share, particularly for sub-6GHz 5G base stations

With the sub-6GHz bands dominating 5G rollout for the foreseeable future, the focus is on improving base station efficiency to meet ITU targets on reducing energy consumption per bit compared with 4G. Macrocells still account for the majority of new base stations, and in the 5G macro RF front end (RFFE) GaN PAs are now rapidly overtaking the LDMOS amplifiers that have dominated the market since their introduction with GSM in the 1990s.[2]

There is also growing interest in the higher frequency bands, around 4 – 5GHz, where the 5G performance of LDMOS is inadequate compared with that of GaN devices. At these higher frequencies too, massive MIMO is becoming popular to achieve the capacity and high data rates required for cells in densely-populated urban areas, particularly in Asia. This requires the development of base stations with higher levels of RFFE integration, and therefore demands components with smaller size, better linearity, higher output power and reduced power consumption, as well as wider bandwidth and increased receiver sensitivity: only GaN devices can meet these needs.

The performance benefits of GaN in terms of higher power density and elevated operating temperature are well-known, and PRFI has many years of experience in optimising GaN PAs for a range of demanding applications such as 4G and 5G base stations, including the use of Doherty topologies.

Liam Devlin

[1] https://www.opensignal.com/2021/04/28/quantifying-the-mmwave-5g-experience-in-the-us

[2] https://www.embedded.com/5g-and-gan-the-shift-from-ldmos-to-gan/

[3] https://www.prfi.com/wp-content/uploads/2019/04/ARMMS_3p5_GHz_Doherty_MMIC_v5.pdf