Building and Testing the Next-Generation High-Performance Wi-Fi 6E Devices

With the FCC’s Report on Order establishing rules for unlicensed devices in Wi-Fi 6E and the IEEE 802.11ax rules of operation, Wi-Fi 6E device makers have a lot to consider. As exciting as this new Wi-Fi spectrum availability is, it is critical that new Wi-Fi 6E devices meet the stringent requirements for performance and interoperability.

Challenges to Building the Next Generation, High Performance Wi-Fi

Building on the analogy of Wi-Fi 6E as a new, large freeway that only allows the fastest cars, how can device makers build the next generation of high-performance Wi-Fi devices that can take advantage of this highway of brand new spectrum? It’s exactly like building a high-performance sports car. There are many challenges to overcome, the below are a few that are particularly demanding.

• 1200 MHz of additional spectrum added to Wi-Fi devices. It is double the frequency range coverage needed in the past for 2.4 GHz and 5 GHz bands. This can be particularly challenging for Wi-Fi 6E design, especially for the RF front end, because there is a need to deliver consistent performance across the entire spectrum from the low channels to high channels. You also need excellent linearity of the power amplifiers. Peak performance typically starts to roll off when you reach the higher frequency, or the edge of the band and devices will need to be tested to the very highest channels to make sure that they can operate at the expected power levels. Calibration of the transmitter power is very important and will be needed for consistent performance.

• 160 MHz channels were already defined in the previous Wi-Fi 5 (802.11ac) generation, but they were not mandatory and were not often supported or deployed. With Wi-Fi 6E however, deployments will make full use of these wider channels because there is now sufficient contiguous spectrum. With wider bandwidth, you can have more distortions of the OFDM subcarriers as they cover a wider frequency range. The important metric to focus on for these wider channels is the spectral flatness to ensure even distribution of power. Also, wider channels mean lower SNR per carrier, therefore it requires excellent transmitter modulation performance.

• OFDMA, the multi-user version of OFDM, is part of Wi-Fi 6 in the 2.4 GHZ and 5 GHz band, but in Wi-Fi 6E it will be even more prevalent because there will be no legacy devices operating in the 6 GHz band. This means all the devices in the 6 GHz band will be able to take advantage of OFDMA. For each transmission in highly congested areas, there will be multiple devices able to share the bandwidth to improve capacity and reduce latency. OFDMA is a very powerful feature, but it’s also one of the most challenging aspects of the IEEE 802.11ax standard because it requires all devices participating in the transmission to be synchronized. One bad actor can ruin the transmission for the others. All of the client stations participating in the transmission must be synchronizing time, they must have their frequency aligned and they must transmit power that is accurate.

• 1024 QAM modulation was introduced in the IEEE 802.11ax standard and carries 10 bits per subcarrier. This improves peak data rates by 25 percent over previous versions, which is how the highest data speed is achieved. Because the high modulation rates can only be used in very good RF conditions, the 6 GHz spectrum will provide a better and cleaner environment with less interference from other devices since it has enough spectrum to avoid adjacent channels or overlapping channel interference. 1024 QAM also requires the highest level of modulation accuracy. This accuracy is usually measured by EVM (error vector magnitude) that measures the deviation of the constellation points compared to their ideal location.

Devices operating in the 6 GHz band must coexist with incumbent devices. Therefore, Wi-Fi 6E access points and clients must comply to regulatory defined emissions limits in order to avoid interference with other devices within the band or in adjacent bands. Spectral masks define the limits of the distribution of power across the channel and into the adjacent channels. It’s important to check that the spectral mask can be met for all the channels and especially to identify the worst case scenarios at the channels that output the highest power.

LitePoint Wi-Fi 6E Test Solutions

When developing Wi-Fi 6E devices, compliance verification and performance validation will be imperative to ensure these devices can really take advantage of this new spectrum. LitePoint has innovative, high performance testing solutions that can help device makers validate and accelerate Wi-Fi 6E device development.

IQxel-MW 7G™

LitePoint’s IQxel-MW 7G™ is the first fully integrated tester for Wi-Fi 6 and Wi-Fi 6E. This test solution supports a continuous frequency range from 400 MHz to 7.3 GHz and features native support for per-port 160 MHz and 80+80 MHz signal combination. The IQxel-MW 7G has the best in class, residual EVM performance that’s needed for 1024 QAM testing and supports packet detection and timing requirements needed for Wi-Fi 6E advanced testing of features like multi-user OFDMA.

IQxel-MW 7G supports legacy Wi-Fi standards, thereby ensuring coverage for Wi-Fi 802.11 a/b/g/n/ac and 802.11ax testing in the 2.4 GHz, 5 GHz and 6 GHz bands. In addition to Wi-Fi, the test system delivers high performance verification for the most popular wireless connectivity standards including WLAN legacy, all Bluetooth device standards (1.x, 2.x, 3.0, 4.x, 5.x), including cellular TDD and FDD non-signaling test modes for 2G/3G/4G and 5G cellular technologies.

The test platform is well suited for use in design verification and manufacturing testing.

IQfact+™ Software

IQfact+™ software is a test automation solution that combines device under test (DUT) and tester control. This software provides turnkey testing and calibration for leading Wi-Fi chipsets, enabling thorough design verification and rapid volume manufacturing with minimal customer engineering effort.

Each IQfact+ software is tailored to provide the best test efficiency for a specific chipset and is designed specifically for the LitePoint tester architecture, resulting in drastically reduced test time and engineering effort. IQfact+ encompasses a growing library of over 350 chipsets and supports all key wireless connectivity technologies.

With IQfact+ turnkey solutions developed for Wi-Fi 6 and 6E chipsets, the IQxel-MW 7G tester provides an out-of-the-box calibration and verification solution that can help device makers accelerate time to market.

Content source: Next Generation Wi-Fi 6E Devices | LitePoint