A Q&A with Khushboo Kalyani, Product Manager, Wireless Connectivity and Cellular Test Systems, LitePoint

Q1: You’ve been representing LitePoint at various Wi-Fi industry events. What is Wi-Fi 7 bringing to the table that’s new and interesting?

Khushboo: At LitePoint, we expect to start seeing Wi-Fi 7 used more widely in IoT applications, which will be a key growth driver, in addition to more conventional uses in clients such as smartphones, access points, gateways, laptops and tablets. These emerging IoT uses cases could include Wi-Fi 7 adoption in devices such as smart TV speakers, home door locks and other smart home sensors.

Today, there are different technologies used by IoT devices. Approximately a third of them operate on low-power long range wide area network technologies like Sigfox, LoRa, HaLow, NB-IoT, CAT-M and such. Another third uses wireless personal area network (WPAN) technologies like Bluetooth, Zigbee, Z-Wave or similar. The remaining third or less use Wi-Fi. Based on what I’m hearing from customers, I think people are concluding that Wi-Fi can easily – and equally – serve the IoT category.

That is especially true among applications that are latency-sensitive, which will benefit from Wi-Fi 7’s new low-data-rate modulation coding schemes, MCS14 and MCS15. These schemes were introduced to increase reliability and maximize transmission range in the 6GHz band for low-power IoT devices.

Q2: What are the broader implications for IoT adoption of Wi-Fi 7?

Khushboo: In many applications today, Wi-Fi is already omnipresent. That has sparked a larger conversation on the adoption of Wi-Fi across IoT devices, where they can leverage existing Wi-Fi infrastructure and simplify deployment within industrial, home and enterprise applications. This, in turn, will facilitate scalability and minimize interoperability issues.

Key chipset companies around the globe are already leading the way with low-power W-Fi solutions. 

Q3: How are these emerging Wi-Fi 7 chipsets for IoT applications keeping a tight rein on power budgets?

Khushboo: IoT devices do not require a constant active internet connection. With that in mind, Wi-Fi 6 introduced a feature called target wake time (TWT). This feature allows devices to negotiate when and how often they will wake up to send or receive data, significantly reducing power consumption by minimizing unnecessary wakeups. Although the feature was introduced in Wi-Fi 6, we expect it to take off in Wi-Fi 7 and beyond.

Additionally, chipsets can implement custom low-power listening modes, which enhance efficiency when listening for network activity and further reduces power consumption when monitoring signals.

Q4: What are some of the underlying technical advantages of Wi-Fi 7?

Khushboo: Three features stand out for me. First, is the new 4096-QAM modulation scheme, which allows for higher data rates by packing more bits together but requires higher signal-to-noise ratio or clean-channel conditions and increases radio complexity.

Another feature that is more functional is multi-link operation, which allows more efficient use of spectrum. This feature was not available in previous generations of Wi-Fi and will truly improve practical Wi-Fi deployment and can be used in Wi-Fi 7 and beyond.

For me, this is a differentiating feature compared to previous-generation technology, because it allows you to aggregate multiple channels, whether it’s a 2.4GHz, a 5GHz or a 6GHz channel, or whatever combination of spectrum you have available. This allows you to do a few of things:

• Send different data streams across channels to increase overall throughput 
• Send the same data stream across multiple channels to increase redundancy 
• Perform dynamic channel switching in real-time to improve the opportunities for high-priority transmission.

The other thing multi-link operation enables is a more optimized use of the 6GHz band, which has not been adopted uniformly across all countries for unlicensed use. Now, whichever geographic region you’re serving, Wi-Fi 7’s multi-link operation will allow you to fully utilize your available spectrum efficiently.

The third important feature is preamble puncturing, a very useful capability that enables efficient spectrum utilization. It is particularly beneficial in the 5GHz band where an incumbent would otherwise prevent the entire channel’s use. By allowing transmissions to occur even in the presence of narrowband interference, preamble puncturing enhances overall throughput and spectral efficiency.

Q5: With the proliferation of Wi-Fi 7, what do customers need to know about test requirements?

Khushboo: What is driving change is the need for 160MHz and 320MHz test capability. In the past, 20MHz, 40MHz and 80MHz were the channel bandwidths available in the 2.4GHz and 5GHz spectrum and were deployed in a typical enterprise access point or home set-up.

With Wi-Fi 7, despite the lack of practical deployment, customers are still eager to highlight the capability of 320MHz or 160MHz Wi-Fi across six or seven channels. For that reason, they need equipment with the capability to test that much bandwidth either during R&D or as part of manufacturing or design validation testing. LitePoint has the equipment capable of testing with supreme accuracy at 320MHz and 160MHz.

Customers also need equipment with excellent error vector magnitude (EVM) performance that is at least 8dB to 10dB better than the device’s performance. This is to ensure that the tester does not introduce any inaccuracies to the device measurement.  

Another critical aspect to test is UL-OFDMA. For this feature to work accurately, client devices must be synchronized to avoid interference and align correctly within the allocated subcarriers. From a testing perspective, this involves measuring carrier frequency offset and transmission timing accuracy to ensure synchronization within a specific tolerance.

Another important aspect to validate is spectrum mask for a PPDU containing punctured channel(s). The IEEE spec has defined a definitive list of puncturing patterns for OFDMA and non-OFDMA transmissions based on PPDU and puncturing bandwidth. When testing this, the idea is to measure the leakage from the occupied subchannel(s) into the punctured subchannel(s) to ensure it is low and will not cause any interference.

In addition to all the standard tests on power, transmit center frequency leakage, receiver sensitivity, spectral flatness and more must be performed to ensure accurate calibration and transmit and receiver RF parametric verification.

Q6: How is LitePoint engineering your test equipment to keep ahead of customer requirements? As they integrate multiple wireless standards into their chipsets, for example, are they expecting a similar level of integration with your test platforms?

Khushboo:  We have seen integrated chipsets and modules supporting Wi-Fi and Bluetooth for a while now in the market and recently some chipset companies have announced solutions that integrate Ultra-wideband (UWB) technology as well into the mix. From a test perspective each of these technologies needs to be tested well, as their underlying implementation is different thus requiring different RF PHY characteristics to be validated, they operate on different frequency ranges, bandwidths and thus they may have different test times.

While integrated chipsets are advancing, the choice of test equipment depends on many factors, since the requirements vary significantly between R&D to production. As an example, generally R&D & design validation groups tend to have dedicated teams specifically focusing on characterization and validation of a specific technology which requires purpose-built testers with advanced features and accuracy. QA teams on the other hand may find some value in an integrated platform as their test plan includes end product performance validation, interoperability tests or coexistence tests as some of these technologies share antennas and common frequency bands. If you look at manufacturing there KPI’s are centered around equipment reliability, longevity, yield, throughput, support for customized automation tool, cost of test and test times as they can vary drastically for each of these technologies. As you can see there are multiple factors that play a role in designing a tester and the requirements vary based on the product development stage.  So honestly there is no one-size tester that fits all and hence we work closely with our customers to see what makes sense for them in terms of technology, cost and more.

Q7: In closing, what sets LitePoint apart from other companies offering Wi-Fi test?

Khushboo: Our motto is “simplifying test through innovation”.  As each generation becomes more complex, we strive to provide a simplified testing solution so you can focus on your product. We achieve this by building high-performance test systems and offering strong, continued customer support. 

LitePoint’s comprehensive availability of automation solutions, the most extensive in the industry, sets us apart. Our IQfact+ software tool is known in the industry for simplicity and ease of use. Additionally, we’ve been the first movers in test to offer a fully integrated non-signaling solution for every Wi-Fi standard that’s come along. Our close collaboration with leading chipset vendors enables us to develop turnkey, chipset-specific solutions that meet your testing needs effectively.