How Much Improvement Does Wi-Fi 7 Bring?

Wi-Fi 7 supports blazing speeds.

Building on its predecessor Wi-Fi 6 (also known as 802.11ax), Wi-Fi 7 supports Extremely High Throughput (EHT), with raw data rates of up to 46 Gbps and 16 spatial streams defined in the standard specifications.

This is much faster than 10 Gbps Ethernet running on Cat 6/6a/7 cables. The closest access and connection technologies are Thunderbolt 3/4, USB 4, and HDMI 2.1, offering maximum raw data rates of 40Gbps or higher.

Wi-Fi 7 will support 320MHz channel bandwidth, which is double that of Wi-Fi 6.

Wi-Fi 7 also increases the QAM granularity from 1024 (1K) to 4096 (4K), resulting in a 20% speed increase compared to Wi-Fi 6/6E or Wi-Fi 5 Wave 3.

Additionally, Wi-Fi 7 doubles the maximum number of spatial streams, which in some cases can be exchanged with the number of antennas, increasing from 8 to 16. Therefore, the maximum of 9.6 Gbps supported by Wi-Fi 6/6E for 8 spatial streams increases to 46 Gbps for Wi-Fi 7 with 16 spatial streams.

At these extremely high speeds, users can achieve up to 5.8 Gbps on common devices such as smartphones and laptops using two Wi-Fi antennas (two spatial streams).

Many devices that use a single antenna can also support data rates of up to 2.9 Gbps due to strict power or form factor limitations. Users can achieve more than double the speed without paying for additional antennas or higher electricity bills, as no extra power amplifiers or front-end modules are needed—this is a paradigm shift for many future applications.

Latency is another critical parameter for Quality of Service (QoS) and user experience.

It is especially crucial for real-time applications. Many multimedia applications, such as high-resolution real-time video streaming, virtual reality, augmented reality, cloud gaming, and real-time programming, require latency of less than 20 milliseconds.

Achieving such low latency in a wireless environment is not easy. For fiber access, the latency between the WAN side, modem, and cloud/server is about 10 milliseconds or slightly longer.

Considering this, the latency budget between WAN modems and endpoint client devices should be around 10ms or less for a good user experience. Wi-Fi 6 achieves 10-20ms latency.

Moreover, Wi-Fi 6E can achieve lower latency in much less contested environments. Wi-Fi 7 will help reduce latency to below 10 milliseconds, ultimately reaching a range of less than 1 millisecond with deterministic boundaries by using various tools in the 802.11be standard.

These tools include MLO, time wave transformation (TWT), and rTWT, improved trigger transmission, and eventually integrated time-sensitive networking (TSN) capabilities.

As mentioned earlier, MLO provides a dynamic mechanism to adapt connections between multiple links.

MLO can dynamically balance the transmission load between two link peers (such as APs and client devices) based on metrics such as link performance and robustness, i.e., load balancing.

If one link experiences interference or link loss (e.g., due to range), the connection can still operate over the remaining links, and the transmission can seamlessly switch from the faulty link to a good link (also known as fast failover).

MRU/RU and preamble puncturing also benefit connection robustness. For example, when a specific sub-channel or segment of the frequency of the running channel experiences interference, the AP can avoid using those interfered sub-channels or RUs/MRUs and optimize transmission based on the current environmental conditions and channel status. Furthermore, MCS 14 and MCS 15 are defined to improve signal-to-noise ratio, enhancing connection robustness as the distance between link peers increases.

Wi-Fi 6 and Wi-Fi 6E have enhanced many features for reducing interference and coexisting with existing devices based on Wi-Fi 5.

Wi-Fi 6 provides a more flexible sub-channel puncturing mode and can utilize RUs in OFDMA mode to avoid finer-grained interference, detailed down to 2 MHz (with a minimum RU of 26 tones).

Wi-Fi 6E supports automatic frequency coordination (AFC) for coexistence with existing devices.

Wi-Fi 7 features MRU and maximum flexible preamble puncturing, supporting all possible sub-channels and high-resolution puncturing modes in both OFDMA and non-OFDMA (MU-MIMO) modes, providing better interference mitigation and optimal QoS for different types of traffic.

MLO also improves the seamless roaming user experience.

It provides built-in roaming enhancements defined in the 802.11be standard. For example, when a device moves away from an AP, MLO retains the ML (multi-link) connection between the AP and the device, allowing it to operate automatically on the 2.4 GHz band without needing to switch bands.

Conversely, if the device approaches the AP, MLO can automatically and dynamically operate on the 5 GHz and 6 GHz bands for better performance.

Today’s Wi-Fi 6 and 6E APs must rely on application-layer band steering or client steering features to force clients to different bands. It does not always work as expected since APs cannot control client devices; client devices decide whether to switch bands. Additionally, compatibility between vendors is another significant challenge for seamless roaming.

In terms of spectral utilization, Wi-Fi 7 offers higher efficiency than Wi-Fi 6/6E.

Additional efficiency can benefit from various Wi-Fi 7 features, MRU, preamble puncturing, MLO, 4096 QAM, future 16 spatial streams, and coordinated multi-AP functionalities, such as coordinated beamforming, coordinated OFDMA, joint transmission, etc.

By utilizing higher speeds, benefiting from broader 320 MHz channel bandwidth, 4096 QAM, and lower latency, Wi-Fi 7 delivers data with higher power efficiency.

Building on the power-saving features of Wi-Fi 6, Wi-Fi 7 improves these functions in various ways to achieve optimal power savings.

With MLO, client devices do not need to listen for every Delivery Traffic Indication Message (DTIM) beacon frame, nor perform group time key, integrity group time key, or beacon integrity group time key (GTK/IGTK/BIGTK) updates.

Clients can maintain a link for DTIM beacon updates, traffic indications, and BSS key updates while keeping other links in deep sleep mode without needing to wake up regularly for DTIM beacon updates.

In addition to the most promising power-saving feature TWT in Wi-Fi 6, Wi-Fi 7 also supports a so-called trigger transmission opportunity (TXOP) sharing feature that further saves power. It allows the AP to allocate a portion of time within the acquired TXOP to associated client devices for transmission, thus the AP does not need to wake up in the next service period (SP).

Onsemi also supports many proprietary dynamic adaptive energy-saving features based on actual application, real-time throughput, and environmental (such as temperature) demands.

In recent years, Wi-Fi sensing applications, such as motion detection, positioning based on Wi-Fi Channel State Information (CSI) (especially indoors), fine time measurement/round-trip time (FTM/RTT), have garnered significant interest from service providers and end users.

Wi-Fi channels are susceptible to interference, exhibiting strong dynamics and frequency selectivity, and CSI contamination can greatly reduce the accuracy of motion detection. Thanks to the 320 MHz channel bandwidth, Wi-Fi 7 supports richer CSI data, up to 3984 tones, improving the accuracy of motion detection.

Moreover, since such a large amount of CSI data can be captured during the 320 MHz transmission, it is possible to select enough interference-free CSI blocks for motion detection while avoiding noisy CSI data.

Through 2x or 4x oversampling and upsampling techniques, for 320 MHz signals, RTT timestamps and measurement accuracy can achieve sub-nanosecond resolution. In other words, Wi-Fi 7 supports sub-meter (i.e., 30 cm) accuracy for ranging and indoor positioning, enabling many exciting new Wi-Fi sensing applications.

Wi-Fi 7 will significantly improve user experience in many aspects and become more cost-effective. It can enable and enhance many demanding applications such as cloud gaming, immersive AR/VR, 8K video streaming, and Industry 4.0.

Users can expect Wi-Fi 7 to provide higher speeds, lower latency, and stronger performance compared to existing Wi-Fi 6/6E.

Source: Telecom Encyclopedia, with permission for reproduction.

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