Overview of Wi-Fi 7 (IEEE 802.11be)

Continuous innovation in Wi-Fi^® technology aims to meet the increasing demands of customers, fueled by the digitalization of homes, enterprises, and hotspot areas. As such scenarios increasingly demand wireless data services, their needs surpass what Wi-Fi 6 can offer. Recently, video traffic has become the primary type of traffic, with 4K and 8K resolution content in particular requiring very high bandwidths. Due to increasing factors such as increased home digitalization and the popularization of high-resolution video streaming, customer demand for reliable high-bandwidth, low-latency wireless connectivity has surpassed the capabilities of Wi-Fi 6. To address this demand, the IEEE^® [1] proposed the next generation of Wi-Fi, Wi-Fi 7, also referred to as IEEE 802.11be™ Extremely High Throughput (EHT). The fundamental objective of Wi-Fi 7 is to provide extremely high throughput, ensure deterministic low latency, and enhance network capacity that can support a minimum throughput of 30 Gb/s at the access point (AP), which is four times the rate of IEEE 802.11ax™ or Wi-Fi 6, across carrier frequencies ranging from 2.401 GHz to 7.125 GHz.

Comparison of Wi-Fi 7 and Wi-Fi 6

Wi-Fi 6 primarily focuses on increasing channel capacity by using multiuser (MU) technologies such as orthogonal frequency-division multiple access (OFDMA) and multiuser-multiple input multiple output (MU-MIMO). Wi-Fi 7 builds on these improvements, significantly boosting performance by lowering latency, introducing EHT, and increasing channel capacity through more efficient spectrum usage. This table compares the key features of Wi-Fi 6 and Wi-Fi 7.

Characteristics	Wi-Fi 6	Wi-Fi 7
IEEE standard	IEEE 802.11ax	IEEE 802.11be
Bandwidth	20 MHz, 40 MHz, 80 MHz, 80+80 MHz, and 160 MHz	Up to 320 MHz
Frequency bands	2.4 GHz, 5 GHz, and 6 GHz	2.4 GHz, 5 GHz, and 6 GHz
Maximum data rate	9.6 Gbps	46 Gbps
Multilink operation (MLO)	Not supported	Supported
Modulation	1024-quadrature amplitude modulation (QAM) OFDMA	4096-QAM OFDMA
MIMO	8×8 MU-MIMO	8×8 MU-MIMO
Resource units (RUs)	Does not support multi-RUs	Supports multi-RUs
Security protocol	WPA3	WPA3

Compared to Wi-Fi 6, the Wi-Fi 7 standard increases channel bandwidth to 320 MHz, boosts throughput and capacity with 4K-QAM modulation, and brings in new features like MLO and channel efficiency improvements such as preamble puncturing support for single user (SU) transmissions. These developments ensure lower and more consistent latency, even in crowded settings. Designed for both home and enterprise use, Wi-Fi 7 supports immersive and high-demand applications.

Key Characteristics of Wi-Fi 7

These are some of the key features of Wi-Fi 7.

MLO

Existing Wi-Fi 6 devices support multiband operations across the 2.4 GHz, 5 GHz, and 6 GHz bands. However, these operations are independent, lacking coordination and significantly reduce efficiency. To address this, Wi-Fi 7 introduces MLO capability, a combined framework that manages multiple links, optimizing resource use across them. These are the fundamental advantages of MLO.

• The introduction of MLO significantly enhances coordinated operations across multiple links, offering a stark contrast to the traditional, isolated operations over multiple bands in existing Wi-Fi technologies.

• The simultaneous use of multiple links boosts channel access opportunities, markedly reducing latency.

• For data requiring high reliability, MLO supports duplication across links to ensure successful transmission.

• MLO enables you to assign data flows to specific links, catering to the unique needs of applications and achieving effective traffic separation and differentiation.

The Wi-Fi 7 standard introduces a unified framework for managing multiple links through the concept of a multilink device (MLD). An MLD can simultaneously connect with another MLD across several bands. A single MAC service access point (MAC SAP) manages each of these connection links, providing coordination among them. Consequently, Wi-Fi 7 devices can aggregate bandwidth for faster speeds and ensure more reliable Wi-Fi connections by using multiple bands simultaneously.

This figure shows the different MLO modes that the IEEE P802.11be™/D5.0 draft standard defines.

• Single-radio — A single-radio MLD operates on a single radio, but can still support multiple links. However, because the MLD has only one radio, you cannot use multiple links at the same time. The single radio must alternate between multiple links in a time-domain multiplex (TDM) manner. Because, switching links with a single radio typically requires time and additional signaling. Therefore, the single-radio operation limits you to statically switching links, which means, you might need to keep the radio on one band to complete a data transmission session before switching to another band. However, since many single-radio MLDs come with at least 2×2 MIMO capability that you can repurpose to boost throughput and reduce latency, nearly matching the performance of a dual-radio MLD. Therefore, Wi-Fi 7 introduces an improved version of single-radio MLD, called Enhanced multi-link single-radio (EMLSR). This figure shows the frame exchange between a dual-radio AP MLD and single-radio STA MLD operating in EMLSR mode.

  In the EMLSR mode of MLO, an STA MLD, equipped with multiple receive chains, listens on a set of active links. Initially, Link 1 and Link 2 are in the listening phase. This phase includes executing clear channel assessment (CCA) and receiving the initial control frame (ICF) from an AP MLD. Link 1 secures channel access, leading to the transmission of a PHY protocol data unit (PPDU) from STA1 to AP1. Concurrently, Link 2 remains inactive. At the end of the transmission on Link 1, both Link 1 and Link 2 resume active channel listening. Link 2 then secures channel access, prompting AP2 to transmit a multiuser request to send (MU-RTS) ICF to STA2 on Link 2. Throughout the transmission period on Link 2, Link 1 is inactive. For more information about how you can perform 802.11be system-level simulation using EMLSR MLO, see the 802.11be System-Level Simulation Using EMLSR Multilink Operation example.

• Multi-radio — In the multi-radio mode, you can communicate on multiple links at the same time. You can operate an STA MLD with multiple receive chains by listening on a set of enabled links, but the STAs connected to the STA MLD must be awake and ready to receive an initial control frame from an AP associated with an AP MLD. This occurs in a non-HT duplicate PPDU environment using one spatial stream, followed by frame exchanges on the link that received the initial control frame. An MLD, when equipped with multiple 802.11be radios, can operate in either the simultaneous transmit and receive (STR) mode or the non-simultaneous transmit and receive (NSTR) mode. Which operation mode the MLD uses depends on the ability of the MLD to concurrently transmit and receive packets across different links. This figure shows a frame exchange between a dual-radio AP MLD and a dual-radio STA MLD operating in STR mode.

  In the preceding figure, the AP MLD and STA MLD are dual-radio MLDs, and can transmit UL and DL frames asynchronously on Link 1 and Link 2 at the same time. For more information about how you can perform 802.11be system-level simulation using STR MLO, see the 802.11be System-Level Simulation Using STR Multi-Link Operation example.

  In NSTR mode, the AP MLD and STA MLD can transmit and receive simultaneously on Link 1 and Link 2, but cannot transmit on one link while receiving on another.

A STA MLD that has multiple 802.11be radios and the ability to dynamically reconfigure spatial multiplexing across multiple links can operate in enhanced multi-link multi-radio (EMLMR) mode.

This table summarizes the different types of MLO modes in Wi-Fi 7.

MLO Mode	Number of Wi-Fi 7 Radios	Characteristics
EMLSR	1	MLSR with additional functionality to enable the simultaneous listening on two links
STR	Greater than or equal to 2	Simultaneous transmission and reception on multiple links
NSTR	Greater than or equal to 2	Non-simultaneous transmission and reception on multiple links
EMLMR	Greater than or equal to 2	Multi-radio with additional functionality to dynamically reconfigure spatial multiplexing on each link

320 MHz Bandwidth

Wi-Fi 6 devices suffer from low quality-of-service (QoS) due to the overcrowded and limited unlicensed spectra in the 2.4 GHz and 5 GHz bands, especially with the introduction of new applications. To achieve a maximum throughput of at least 30 Gbps, Wi-Fi 7 introduces new bandwidth modes, including contiguous 320 MHz, and non-contiguous 160+160 MHz. This figure shows a comparison of the channel bandwidths on which Wi-Fi 7 and Wi-Fi 6 devices communicate.

Wi-Fi 7 devices can tap into the full potential of the 6 GHz band, effectively doubling their bandwidth compared to the Wi-Fi 6 devices.

4096-QAM Modulation

The highest order modulation Wi-Fi 6 supports is 1024-QAM, enabling each modulation symbol to carry up to 10 bits. This figure shows how Wi-Fi 7 enhances this capability by introducing 4096-QAM, enabling each modulation symbol to carry 12 bits.

Using the same coding, 4096-QAM achieves a 20% rate increase over 1024-QAM. Users can achieve greater transmission efficiency with a higher transmission rate, resulting in faster downloads and uploads. This makes it ideal for 4K and 8K streams and other media-rich experiences.

Multi-RUs and Preamble Puncturing

Wi-Fi 6 users must send or receive frames on their allocated RUs, which significantly limits the flexibility of spectrum resource scheduling. To enhance the spectrum efficiency and address this limitation of Wi-Fi 6, Wi-Fi 7 introduces a mechanism that enables the allocation of multiple RUs to a single user. This figure compares RU allocation in Wi-Fi 6 and Wi-Fi 7.

The multi-RU allocation capability in Wi-Fi 7 aims to improve flexibility in spectrum resource scheduling. By assigning multiple RUs to a single user and combining them, Wi-Fi 7 can enhance transmission efficiency. To ensure a balance between spectrum use and implementation complexity, the standard specifications [1] allow for a limited mix of multi-RU combinations when the bandwidth is 160 MHz or less. Specifically, you can combine small-size RUs (fewer than 242 tones) with other small-size RUs, and large-size RUs (242 tones or more) with other large-size RUs. However, the standard does not support combining small-size RUs with large-size RUs. This table shows the applicable multi-RU combinations for different bandwidths in Wi-Fi 7.

RU Size	Allowed RU Combinations
Small-size RU 26-tone 52-tone 106-tone	26-tone RU + 106-tone RU for 20 MHz and 40 MHz 26-tone RU + 52-tone RU for 20 MHz, 40 MHz, and 80 MHz
Large-size RU 242-tone 484-tone 996-tone 2×996-tone 3×996-tone	242-tone RU + 484-tone RU for 80 MHz 484-tone RU + 996-tone RU for 160 MHz 242-tone RU + 484-tone RU + 996-tone RU for 160 MHz 484-tone RU + 2×996-tone RU for 240 MHz 2×996-tone RU for 240 MHz 484-tone RU + 3×996-tone RU for 320 MHz 3×996-tone RU for 320 MHz

Wi-Fi 6 introduced preamble puncturing as an optional functionality exclusively for multiuser (MU) transmissions. Wi-Fi 7 expands this functionality to SU transmissions, significantly enhancing spectrum efficiency and flexibility in environments affected by wireless interference from overlapping Wi-Fi networks and non-Wi-Fi sources. This figure shows how preamble puncturing technique in Wi-Fi 7 maximizes channel bandwidth in the presence of interference.

Unlike previous generations of Wi-Fi, where interference on a channel could prevent the use of the remaining spectrum, the preamble puncturing technique effectively isolates the affected part of the spectrum. This isolation enables you to fully use the rest of the channel, enhancing spectrum efficiency, by enabling wider channels in the face of interference, and accelerating data transmissions.

References

[1] "IEEE Draft Standard for Information Technology–Telecommunications and Information Exchange between Systems Local and Metropolitan Area Networks–Specific Requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment: Enhancements for Extremely High Throughput (EHT).” IEEE P802.11be/D5.0, November 2023, January 2024, 1–1045. https://ieeexplore.ieee.org/document/10381585

[2] Chen, Cheng, Xiaogang Chen, Dibakar Das, Dmitry Akhmetov, and Carlos Cordeiro. “Overview and Performance Evaluation of Wi-Fi 7.” IEEE Communications Standards Magazine 6, no. 2 (June 2022): 12–18. https://doi.org/10.1109/MCOMSTD.0001.2100082.

[3] Lopez-Perez, David, Adrian Garcia-Rodriguez, Lorenzo Galati-Giordano, Mika Kasslin, and Klaus Doppler. “IEEE 802.11be Extremely High Throughput: The Next Generation of Wi-Fi Technology Beyond 802.11ax.” IEEE Communications Magazine 57, no. 9 (September 2019): 113–19. https://doi.org/10.1109/MCOM.001.1900338.

[4] López-Raventós, Álvaro, and Boris Bellalta. “Multi-Link Operation in IEEE 802.11be WLANs.” IEEE Wireless Communications 29, no. 4 (August 2022): 94–100. https://doi.org/10.1109/MWC.006.2100404.

[5] Deng, Cailian, Xuming Fang, Xiao Han, Xianbin Wang, Li Yan, Rong He, Yan Long, and Yuchen Guo. “IEEE 802.11be Wi-Fi 7: New Challenges and Opportunities.” IEEE Communications Surveys & Tutorials 22, no. 4 (2020): 2136–66. https://doi.org/10.1109/COMST.2020.3012715.