By Adam Smith
Editor’s Note: You can read Part 1 of this piece here.
Life moves pretty fast. If you don’t stop and look around once in a while you could miss it.
Wi-Fi has never been more important than it was in 2020, with distance learning and remote working stressing our home network connections, bogged down by waist-up video conferencing. Compared to previous years of simply streaming large amounts of video download data, video conferencing exposed the importance of uplink data traffic, both on the home broadband service as well as the multiple, simultaneous Wi-Fi devices operating at home.
The timing could not be better for the latest generation of Wi-Fi, branded as “Wi-Fi 6,” to come to market. Wi-Fi 6 devices use a more efficient means of communicating, allowing multiple devices to simultaneously communicate with the home access point. Wi-Fi 6 will make existing broadband connections feel faster since the devices in the home will not have to wait in line to take their turn, as was the case with previous generations of Wi-Fi. Wi-Fi 6 is currently shipping in volume in phones, PCs, and access points.
Additionally, we saw the release of over 1 GHz of pristine, unlicensed spectrum for commercial use in the 6 GHz band. This started in North America in 2020 and is gaining momentum globally. This new spectrum is like a multi-lane highway reserved for Wi-Fi 6 devices (branded as “Wi-Fi 6E”), enabling a huge improvement in user-experience and paves the way for new innovations for the next generation of Wi-Fi devices. Wi-Fi 6E devices are starting to deploy in this new spectrum and will accelerate as governments around the world open up additional unlicensed spectrum. While the underlying technology in Wi-Fi 6E does not change, making use of the 6 GHz spectrum does introduce some interesting RF calibration and test challenges: wider channels, transmitter quality and emissions requirements, and operation up to 7.1 GHz to name a few.
However, there is no time to stand still. Even though Wi-Fi 6E devices are not widely available yet, the industry is already working on the next generation of Wi-Fi. While not officially yet being called “Wi-Fi 7,” the next iteration of the IEEE Wi-Fi standard is called 802.11be. The main goal in this generation is to achieve “extremely high throughput” (EHT) and low latency. Think 30 Gbps data rates with single digit millisecond latency.
When we look at how this will be achieved, basically take Wi-Fi 6 and double everything. 160 MHz channels move to 320 MHz channels, 1024 QAM modulation techniques move to 4096 QAM, 8×8 MIMO moves to 16×16 MIMO, and the standard allows for multiple, simultaneous links called “multi-link operation”) similar to carrier aggregation in 4G and 5G cellular technologies. Though 802.11be development is under way, this technology will not be available in commercial products for a few years.
In the near term, validating the design performance of 802.11be silicon requires some significant upgrades to the test equipment performance. In the RF world, measurement bandwidth and signal-to-noise ratio (SNR) are opposite sides of a balloon that we squeeze. It is “easy” to achieve high SNR with low bandwidth, or even high bandwidth with low SNR, but achieving both simultaneously is balancing on the head of a pin. We typically quantify this modulation performance in a measurement called error vector magnitude (EVM). Oversimplifying the challenge, if 802.11be doubles the bandwidth, and doubles the modulation depth (4096 QAM), that means that the instrumentation to measure an 802.11be device’s EVM performance needs to be 4x better than for a Wi-Fi 6E device – in terms of the EVM measurement, this is an additional 6 dB of headroom that is needed in the EVM floor of the equipment.
Additionally, testing MIMO and multi-link operation (MLO) modes of 802.11be devices can create somewhat complex test setups. Imagine 16 simultaneous radios inside a single device operating either at the same frequency, or a combination of aggregating multiple slices of different frequencies. The next generation of 802.11be test equipment will need to deliver performance, flexibility, and (of course) be cost-effective.
Wherever you go, there you are.
Products and sensors have been getting more “situationally-aware” through wireless technologies that can detect position and motion. Prior to the pandemic, use-cases for this included security (i.e., building access, digital car key, mobile payments), tracking, and industrial safety. In a post-pandemic world, an unfortunate phrase was added to our vernacular: contact tracing. This has now been added to our location-based use cases. In fact, part of getting back to some sense of normal in 2020, the NFL employed wearables on their personnel to perform contact tracing and quickly identify and isolate those who might be at risk of COVID exposure after a positive test.
You may not be aware of a lesser-known wireless technology called ultra wideband (UWB) that is starting to gain traction in mobile phones, cars, and wearables. This UWB technology based on the 802.15.4z IEEE standard, and not to be confused with Verizon’s branding of 5G mmWave, has been tailored to achieve very accurate (< 10 cm) and secure distance and direction measurements. The technology works by sending out a series of very short, encoded pulses that allow two devices to determine the time it takes to send and receive these messages. Once you know time, it is simple to determine the distance between the devices since these signals travel at the speed of light.
What makes UWB unique for positional detection is that, like the name implies, it uses a very wide bandwidth signal (at least 500 MHz wide). Unlike other wireless technologies that rely on the bandwidth to transmit a large amount of data, UWB uses the fact that wide bandwidth in the frequency domain corresponds to a short amount of time in the time domain. By having the fine time resolution, UWB can achieve better positional accuracy than other technologies that have the ability to determine position (like Bluetooth, for example).
Testing and measuring UWB devices has some similarity to other wireless technologies. However, unlike 5G cellular or Wi-Fi devices, EVM is not the measurement of interest. Instead, for UWB we focus on a measurement called time of flight (ToF). Measuring ToF requires that the test equipment has a precise triggering mechanism to repeatably report the measured time of the initiating device (also known as the “tag”) or the responding device (also known as the “anchor”).
A new topic for UWB in 2021 is enhancing peer-to-peer communication. UWB technology is well-suited to operate using triangulation, where a polling device compares the response times of multiple anchor devices to determine position. For a peer-to-peer use-case work, the device not only needs to measure the distance, it also needs to determine the angle of the signal that is transmitted or received. This is referred to as the angle of arrival (AoA). Employing AoA requires that the devices have multiple antennas (at least two) at a known spacing. By measuring the small differences in the signals received at each antenna, direction can be calculated. To support these peer-to-peer use-cases, you can expect to see a trend toward implementing multiple antennas.
A certification program is being defined to help a healthy ecosystem of UWB-enabled devices to flourish. Started in 2019, the FiRa Consortium has gathered a broad range of market leaders from diverse fields in the semiconductor, mobile, industrial, enterprise and consumer segments. FiRa members work collectively to ensure seamless UWB fine ranging end user experiences by developing standards and certification programs to foster interoperability.
Roads? Where we’re going, we don’t need roads!
2020 showed us how much we rely on technology to stay connected, and wireless technologies played a huge role in enabling work, school, and life in a challenging year. This year the focus will be on enabling further enhancements in 5G, Wi-Fi, and other technologies that connect us. 5G requires tools to help scale the mass buildout of network coverage and enable devices in the new 47 GHz band. The next generation of Wi-Fi technology is already under development, demanding a step function in device performance. Further enabling positional awareness in our devices will improve convenience and security. As we continue the journey in 2021, we will see 5G and Wi-Fi 6 device adoption dramatically increase, deploying a foundation that enables wireless technologies to provide practical solutions to life’s challenges.