Wi-Fi 7 is the upcoming, latest generation of Wi-Fi, and is promising to offer more extreme single-user throughput performance, but also a host of other features to enhance Wi-Fi’s utility in a variety of scenarios. Increased competition with cellular technologies and other wireless communication services is driving Wi-Fi to include new capabilities for new use cases beyond simple internet connectivity for indoor spaces. There are four major areas of advancement for Wi-Fi 7 compared to earlier Wi-Fi generations: multi-link operations (MLO), physical layer (PHY) enhancements, multi-access point (multi-AP) coordination, and enhanced quality of service (QoS) management.
PHY Enhancements
There are several key PHY enhancements coming with Wi-Fi 7 that promise to improve throughput, support more simultaneous users:
- Multi-resource Unit (MRU) & Preamble Puncturing
- Wider Channel Bandwidths
- Higher Order QAM Modulation
- 16 Spatial Streams
- DL & UL MU-MIMO
MRU and preamble puncturing are features that allow for one or more resource units to be assigned to a single station (STA). MRU is predicted to increase throughput, enhance interference immunity, and lead to more optimal spectrum usage. MRU works with Orthogonal Frequency Division Multiple Access (OFDMA) and can potentially significantly reduce multi-user latency.
Preamble puncturing enables selective puncturing of the overlapping spectrum portions of Wi-Fi channels. This function ensures that critical signals can be sent in clear frequency channel portions even in congested environments, which is a further reliability enhancement and should substantially increase data rates in such environments.
Wider channel bandwidths, namely a shift from 160 MHz maximum to 320 MHz maximum channels in the new 6 GHz band, allows for much higher throughput in conditions that allow for such wide channel bandwidths. For wirelessly tethered AR/VR or 8K content streaming, these wider bandwidths can help to ensure throughput rates to accommodate high throughput wireless network links.
Beyond wider bandwidths, Wi-Fi 7 is also coming with quadrature amplitude modulation (QAM) depths to 4096-QAM (4k-QAM). Deeper levels of modulation complexity allow for more data to be carried as symbols in the transmission. However, higher orders of modulation tend to be more susceptible to interference, noise, and phase noise. This is why Wi-Fi devices will automatically adjust the modulation depth used to accommodate the environment. In relatively clean environments, 4k-QAM promises a substantial throughput boost.
Wi-Fi 6 introduced a maximum of 8 spatial streams between two Wi-Fi devices. Wi-Fi 7 doubles this capability to 16 spatial streams. The combined effect of wider bandwidths, higher modulation complexity, and a doubling of spatial streams for the latest Wi-Fi generation is predicted to allow for a theoretical maximum of 46 Gbps of throughput.
In addition to extremely high single-user throughput, Wi-Fi 7 is bringing in support for uplink (UL) multi-user multi-input multi-output (MU-MIMO) to accompany MU-MIMO for downlink (DL) already established in previous Wi-Fi generations. This is a key enabling technology to allow for simultaneous transmission and reception across multiple devices and all available spatial streams.
Multi-Link Operation (MLO)
MLO are a suite of features and configurations that are designed to enable multiple Wi-Fi devices to be able to communicate simultaneously over several different frequency bands and/or channels. The result of this capability is to significantly enhance reliability, reduce latency, and enhance throughput. There are a few different combinations of MLO depending on the configuration of the Wi-Fi devices and the application requirements, but the root of MLO is that this technology will optimize the connection for specific use cases to ensure the lowest latency, most reliable, and highest throughput connection possible over all available Wi-Fi frequency bands and channels. This is a huge step toward ensuring determinism and achieving single-digit millisecond latencies desirable for augmented reality/virtual reality (AR/VR), high performance gaming, interactivity in streaming, remote work, cloud computing, and the potential for industrial and operations technology/information technology (OT/IT) applications.
Multi-AP Coordination
Though in the early stages of development of IEEE 802.11be it wasn’t clear whether Multi-AP coordination was going to be included. It is now considered likely that Multi-AP coordination key aspect of Wi-Fi 7 and allow for more effective use of available radio resources. Multi-AP coordination features are designed to allow for several APs to coordinate resources in the spaces where they overlap. This will involve optimization of the PHY and MAC layer in multi-AP instances to ensure reliability, maintain low latencies, and ensure throughput optimization. There are several different approaches to Multi-AP coordination, including:
- Coordinated beamforming
- Coordinated joint processing
- Coordinated spatial reuse
- Coordinated time domain multiple access (TDMA)
- Coordinated OFDMA
Enhanced Quality of Service (QoS) Management
There are a host of new QoS management enhancements proposed for Wi-Fi 7. The main key new features are dedicated access categories for connections with critical reliability, latency, and determinism requirements. To thwart Wi-Fi technologies susceptibility to latency deterioration in highly congested environments, many of the QoS management enhancements are designed to allow for sustained single-digit millisecond latencies even during high states of congestion.