Each generation of Wi-Fi has delivered higher data rates with a focus on improving performance for end users. It’s an increasingly tall order—consider the average family surrounded by devices all contending for the same airwaves. Or the same scenario faced by an enterprise user.
Wi-Fi 6 aimed to solve this dynamic in home and at the office. It was a paradigm shift that introduced new functionality and mechanisms to better support multiple users. Close on Wi-Fi 6’s heels came Wi-Fi 6E, which incorporated use of the 6 GHz spectrum.
Anticipating what’s next, the industry has its sights set on Wi-Fi 7, which promises to refine and expand Wi-Fi 6 functionality in the 6 GHz spectrum. It adds new features and mechanisms aimed at finally tackling issues that have persistently snarled certain Wi-Fi use cases.
While higher throughput—up to 12 Gbps—is the main benefit of Wi-Fi 7, it is not achieved easily.
Let’s explore why, and implications, starting with a look at Wi-Fi 7’s core capabilities and benefits.
320 MHz bandwidth for much more data
Similar to Wi-Fi 6E, Wi-Fi 7 uses the 6 GHz spectrum that can support channels as wide as 320 MHz—twice what is supported by Wi-Fi 6E and four times Wi-Fi 6. In fact, with Wi-Fi 7, you can get three 320 MHz channels in the 6 GHz band. Because a wider channel can transmit more data, Wi-Fi 7’s pipe is larger than ever.
But is that spectrum actually usable? Such a wide 320 MHz channel is likely to have an interferer in the band which means sections of the channel might be unusable. Wi-Fi 7 deals with this by using a mechanism to puncture out that part of the spectrum so that it is partitioned, but the rest of the 320 MHz channel can be used.
Elevated order modulation for 20% higher speed
Quadrature amplitude modulation (QAM) conveys data over radio waves using discrete points in the constellation diagram. Each discrete point represents a number of bits of data. The more allowable discrete points, the more data that can be transmitted. Wi-Fi 6 provides 1024 (point) QAM, a 25% increase data rate from Wi-Fi 5. Wi-Fi 7 has increased it another 20% to 4096 QAM, which is 12 data bits per symbol.
The problem with this high order modulation is the impact of channel noise, which makes demodulation difficult. Although 4096 QAM is fast, it needs a high signal-to-noise ratio (SNR) to work properly. That limits its use to short operating distances of about 18 feet—inferior for some applications, but excellent for others, such as virtual reality.
Multiple Resource Units provide better spectrum efficiency
OFDMA improves performance by allowing simultaneous transmissions between multiple clients. With Wi-Fi 6 and LTE, a channel can be divided into Resource Units (RUs), which are frequency groupings. Each device is allocated one RU. To provide better spectrum efficiency, Wi-Fi 7 allows multiple RUs to be allocated to each device, making use of otherwise potentially unused spectrum.
Multi-link operation increases link and channel efficiency
In traditional Wi-Fi mesh networks, each mesh node communicates with the devices close to it on a single band and the mesh nodes communicate with each other. This is sometimes not an efficient approach for device-to-device traffic. Instead, with Wi-Fi 7, multi-link operation (MLO) enables multiple simultaneous links to operate in separate channels, with each link operating independently. For example, 2.4 GHz, 5 GHz and 6GHz radios can all be used as though they were one.
MLO is an important new feature in Wi-Fi 7. It is a unified and consistent framework to consistently manage multiple links, reducing management overhead. By aggregating links on different channels, MLO increases throughput. It also improves latency by using multiple links in parallel for flexible channel access. Reliability can be increased by sending duplicated data on multiple links, and quality of service (QoS) can be improved by assigning traffic to appropriate links.
Enhanced QoS management for priority access
Normally, all devices contend for a single channel on a first come first served basis. This is a non-starter for applications like voice calls, where timing is critical.
Wi-Fi 7 introduced enhanced QoS Management so that devices can request guaranteed time. For example, they would inform the access point that a voice call will need 5 ms every 20 ms. The access point will then pre-allocate the channel if possible. This guarantees access to the channel when the voice packet is transmitted. Enhanced QoS management provides smoother channel access management than previous first come, first served methods.
Restricted service periods for deterministic latency
Latency is important for enhanced reality. Wi-Fi 6 improved latency with OFDMA but, depending on the number of gamers in the house, the latency could fluctuate significantly. Wi-Fi 7 can provide deterministic latency that reserves what you need when you need it.
Wi-Fi 7 testing considerations
Wi-Fi 6’s new features had major testing implications which need to be further refined for Wi-Fi 7. The biggest impact is multi-link operation, which will need new testing methodology and test plans for its more consistent, but a different approach compared to standard mesh device testing. Similarly, testing methodologies need to be enhanced for targeted QoS wait time.
As always, test planning will leverage Wi-Fi Alliance test plans when they become available. In the meanwhile, maintaining an up-to-date testing approach for Wi-Fi 6 and Wi-Fi 6E is essential to keep pace with evolving Wi-Fi technology.
Learn about Spirent’s Test as a Service for Wi-Fi devices and read the eBook Testing Wi-Fi for High-Performance Use Cases.