Pandemic, social distancing, flattening the curve, positivity rates, super-spreader events, quarantining, contact tracing, respiratory droplets, PPE – when we look back on 2020, these might be the obvious reflections. With a significant amount of work, school, and life conducted from home, 2020 highlighted the importance of communication tools and access to wireless connectivity. While many will call 2020 a year to forget, I would like to focus on the technology advancements that we made and look ahead to further innovations in 2021.
We were promised jetpacks
2020 saw a major adoption of 5G cellular technology, with roughly 200 million smartphones shipped in the year. In just the second year of the 5G rollout, this represents more than a 10x year-on-year increase in 5G phone sales. The global forecast for 2021 is that more than 30 percent of all mobile shipments will be 5G-enabled.
But, does it feel like 5G is here? We have all seen the network operator ads promising 5G delivers gigabit per-user mobile connectivity with extremely low latency, enabling an “always connected” experience. Everyone in the commercial always seems to have this amazed look on their face as they are transfixed by something (apparently astonishing) on their phone. Then, we cut to fully self-driving cars on the road, doctors can perform surgeries while 6,000 miles away from their patients, and fashionable, lightweight augmented-reality glasses enable hand gestures to manipulate a meticulously detailed holographic image.
Somehow, it does not seem like that is where we are right now. If you think of 5G as a destination, rather than a journey, today you are likely to be disappointed by reality. True, 5G can deliver eye-popping speed test results if you are near an mmWave tower, but today you need to go to 5G – this kind of 5G does not come to you. The reality is that we are still quite early in the rollout of a broad 5G network, but let’s talk about a few key successes in 5G to date.
First, the non-standalone deployments of 5G are performing well in mobility tests. Unless a user is demanding sustained data download rates, handoffs between a 4G connection, a 5G sub-6GHz (FR1) connection, and a 5G mmWave (FR2) connection is practically invisible. Second, with Apple’s decision to include mmWave 5G in all US models of their latest phone, they have shown that it is a practical technology to incorporate, and competitive pressure on other phone providers should help drive adoption and demand for mmWave. The technology meets the economic and form factor demands of a smartphone, and with intelligent software, the mmWave connectivity will not unnecessarily suck your battery dry unless you are in a data-hungry use case. Lastly, deployments of mmWave 5G are focused on the wider bandwidth modes (today, 800 MHz), which allow the data sessions to be short, as they can efficiently pack a copious amount of data into brief transmissions. This not only aids (again) in mobile battery management, but it also frees up the airwaves for other users to transmit their data.
In 2021, we will continue to see methodical buildouts of mmWave 5G infrastructure across cities in the US. Over time, coverage will grow from a few city blocks to relatively high urban coverage to some spill out into the suburbs. This buildout will require the deployment of mmWave small cell and repeater infrastructure, particularly for indoor coverage. Though the deployment of 5G is being marketed primarily as driven by mobile customers (since the mobile data subscriptions are partially subsidizing the huge cost for these buildouts), it is also a trojan horse for the network operators to deploy fixed wireless broadband service. After all, a building is basically a very slow-moving mobile phone. Next generation customer premises equipment (CPE) devices enable end customers to perform installations themselves, with beamforming antenna technology locking on to the network signal.
Manufacturing testing of mmWave small cells, repeaters, or CPEs is similar to testing mmWave smartphones. The test is performed over-the-air (OTA) at a distance appropriate to the far field of the device under test (DUT) antenna array. Because of the physics of mmWave, this distance turns out to be a practical footprint for a manufacturing floor. Additionally, the specific types of measurements made on these infrastructure products are essentially the same, other than different limits based on the 3GPP specification. The main difference in testing small cells or repeaters is that up is down, and down is up. Uplink and downlink cellular communication is not symmetrical by design – the base station is the controller of the communication, and the client devices (phones, CPEs) respond to the control commands. A smartphone transmits an uplink signal and receives a downlink signal. A small cell transmits a downlink signal and receives an uplink signal. The primary impact on test is the requirement for equipment to provide signal generation and analysis for both uplink and downlink test waveforms.
A new development for 5G mmWave in 2021 is the requirement for additional mmWave bands. Since the original Release 15 3GPP specification, the FR2 frequency range defined an operating range up to 52.6 GHz, but no bands were actually defined above 40 GHz. The “mainstream” mmWave deployments have been at 28 GHz and 39 GHz. Over the last two years, the FCC has been auctioning off a 47 GHz band, and now that has completed, silicon development has started.
From a test point of view, the 47 GHz band has a couple of impacts. One subtle impact is that this drives test equipment (and all the associated accessories) to a new connector technology. This impacts all aspects of a test setup: tester, cables, antennas, switches, etc. The commonly used 2.92 mm connector technology works well as a test point for 28 GHz and 39 GHz, but is only rated to 40 GHz. Testing up to 50 GHz frequencies requires moving to 2.4 mm connectors and cables for everything in the signal path. A subtle difference, but a cost impact.
A more significant impact of the 47 GHz band is equipment availability. Today, this frequency is a bit “exotic,” where it is higher than the mainstream 5G frequencies (up to 43.5 GHz) but is lower than the unlicensed 60 GHz frequency range. Lab grade equipment exists to cover this band, but that equipment is expensive, challenging to repeatably set up, and inflexible for automation. Achieving reliable and repeatable results in an automated environment is very difficult as we look to bring up new designs and get them to manufacturing. As we look to commercialize products in the 47 GHz band, simpler, and more integrated solutions are required.