Analysis on the Evolution of Home Wi-Fi Transmission Network Technology

Author: Tang Xiangming, Unit: China Mobile Smart Home Operation Center

Labs Guide

With the rapid development of smart homes, the existing wireless infrastructure has gradually failed to meet users' increasing connection needs, so Wi-Fi 6 and Wi-Fi 7 have emerged. This article will focus on the evolution of Wi-Fi 6 from its emergence to maturity and then to becoming a standard, and what progress has Wi-Fi 7 made compared to Wi-Fi 6.

In recent years, with the rapid development of wireless technology and smart homes, more and more devices need to join the home wireless network. In addition to smartphones and laptops, new devices such as wireless speakers, surveillance cameras, thermostats, refrigerators, and countless other smart appliances and machines have joined the home wireless network.

Part 01 Wi-Fi 6 Technology Evolution Direction

Wi-Fi 6 technology was created as the existing wireless infrastructure running on traditional Wi-Fi standards (802.11a/b/g/n/ac) is increasingly insufficient to cope with the increase in connections and bandwidth requirements.

1.1 Wi-Fi 6 technology is basically mature

Wi-Fi 6 chips started in 2017. Broadcom was the first in the industry to launch the first complete 802.11ax solution, including BCM43684 for the home Wi-Fi market, BCM43694 for the enterprise AP market, and BCM4375 for the smartphone market, which opened the curtain of the Wi-Fi 6 industry. In 2017, Broadcom's BCM43684 Wi-Fi 6 chip was first used in two high-end routers, ASUS RT-AX6000 and RT-AX11000, promoting the rapid development of the Wi-Fi 6 industry.

2020 is a crucial year for the development of Wi-Fi 6 chips. Huawei launched Wi-Fi 6+ routers based on HiSilicon Hi5671Y series Wi-Fi 6 chips, taking the lead in introducing 160MHz bandwidth into the mid- and low-end product market, and instantly detonated the domestic Wi-Fi 6 market with its extremely cost-effective advantages. With this as a node, all mainstream chip solutions have successively released high-, mid-, and low-end Wi-Fi 6 chip solutions, and Wi-Fi 6 technology has been able to develop rapidly.

As of Q3 2021, Broadcom, Qualcomm, Marvell, Mailant, HiSilicon, MediaTek, and Realtek have all achieved mass production and batch shipments of Wi-Fi 6 chips; in addition, main control manufacturers such as Chuangfa Information Technology and ZTE Microelectronics have also launched Wi-Fi 6 main control, which achieves a more comprehensive Wi-Fi solution by adapting to the above-mentioned Wi-Fi chips; at this point, Wi-Fi 6 technology has basically matured.

1.2 Wi-Fi 6E gradually becomes standard

Wi-Fi 6E officially debuted in early 2021, and various chip vendors have announced their own Wi-Fi 6E solutions. In terms of supported terminals, Intel's AX210 wireless network card is the first terminal to support Wi-Fi 6E, but it was the Xiaomi 11 phone equipped with Qualcomm Snapdragon 888 processor in early 2021 that attracted the public's attention to Wi-Fi 6E.

1.3 Differences between Wi-Fi 6 and Wi-Fi 6E

The "E" in the name of Wi-Fi 6E comes from "Extend", which means "extension". Based on the existing Wi-Fi 6 functions, the Wi-Fi 6 spectrum range is further expanded.

Wi-Fi 6E introduces support for the 6GHz band, allowing Wi-Fi 6 to expand to the 2.4GHz/5GHz/6GHz bands based on the original 2.4GHz/5GHz bands. For the 6GHz band, the frequency coverage ranges from 5925MHz to 7125MHz, a total of 1200MHz. The 6GHz band can provide 59 20MHz or 29 40MHz or 14 80MHz or 7 160MHz or 3 320MHz (802.11be, i.e. Wi-Fi 7) independent channels. In contrast, the current available bandwidth of the 5GHz band is only 500MHz (the available frequency in China is only 260MHz), and the available bandwidth of the 2.4GHz band is only 60MHz. In the future, by fully utilizing the full bandwidth of the 6GHz band, the wireless network based on Wi-Fi 6E can fully achieve the effect of doubling the number of devices compared to the Wi-Fi 6 wireless network, in order to solve the bottleneck of insufficient existing Wi-Fi spectrum resources.

Figure 3 Wi-Fi 6E spectrum resources

However, the technologies used by Wi-Fi 6 and Wi-Fi 6E (basic wireless specifications, user experience, key technologies) are basically the same. For example, the 1024-QAM, OFDMA, UL/DL-MU-MIMO, TWT and other mechanisms supported by Wi-Fi 6 are exactly the same in Wi-Fi 6E. Therefore, under the same spectrum resources and environmental interference conditions, the basic performance of Wi-Fi 6E is not stronger than that of Wi-Fi 6. Taking 2x2 MU-MIMO as an example, at a bandwidth of 160MHz, a wireless network based on Wi-Fi 6 can provide a theoretical maximum rate of 2.4Gbps, and Wi-Fi 6E is also 2.4Gbps. The 5GHz band and the 6GHz band are basically the same in terms of rate. In terms of network coverage, the 6GHz band is theoretically higher, and its coverage capability will be slightly inferior to that of the 5GHz band, but the difference between the two is not large. Basically, where the 6GHz band network cannot cover, the 5GHz band basically cannot cover well.

Part 02 Wi-Fi 7 Technology Evolution Direction

According to the definition of the Wi-Fi Alliance, Wi-Fi 7 refers to 802.11be. The development of Wi-Fi 7 standards is still in progress, and the final standard may be released in 2024. This standard is developed based on the 802.11ax standard.

Improvements of Wi-Fi 7 over Wi-Fi 6

Compared with Wi-Fi 6, Wi-Fi 7 has brought many improvements, such as MIMO enhancement, speed up to 30Gbps, three-band simultaneous operation, higher modulation, lower latency, etc. With these cutting-edge technologies, Wi-Fi 7 provides higher data transmission rates and lower latency than Wi-Fi 6. Wi-Fi 7 is expected to support up to 30 Gbps throughput, about three times that of Wi-Fi 6. In terms of application, Wi-Fi 7 can bring users a smoother and faster transmission experience, because it has a larger coverage area and effectively reduces transmission congestion problems, which will more effectively promote the popularization of 8K products. From the user's perspective, Wi-Fi 7 makes online playback of 8K videos no longer a dream, and users will also get a better audio-visual experience. In addition, faster transmission speeds will definitely extend more smart product functions and experiences, such as artificial intelligence interaction and home smart control, solving the current consumer pain points in these areas and obtaining a more comfortable smart experience.

• MIMO enhancement: The maximum spatial stream of Wi-Fi 6 is 8×8, and the maximum spatial stream of Wi-Fi 7 is increased to 16×16. It can greatly increase the wireless bandwidth and client support data, and introduce more advanced CMU-MIMO. Among them, C stands for Coordinated, which means that 16 data streams can be provided by multiple wireless routers at the same time instead of one access point. This is just right for the Mesh WiFi network that has become popular in recent years, allowing terminals to connect to multiple Mesh wireless routers at the same time. In other words, in the future Wi-Fi 7 era, the number of antennas will increase further.
• New 6GHz spectrum, three bands working simultaneously: The Wi-Fi 6 standard uses two frequency bands, 2.4GHz and 5GHz, and the upgraded Wi-Fi 6E introduces a new 6GHz spectrum. Wi-Fi 7 will continue to use the 2.4GHz, 5GHz, and 6GHz frequency bands, and will strengthen the coordinated use of the three bands to obtain a larger bandwidth. In addition, the Wi-Fi 7 bandwidth will also be expanded from the previous 160MHz to 320MHz. Wi-Fi 7 will also support 160+160MHz, 240+180MHZ, and 160+80MHz channels to combine non-contiguous spectrum blocks, which also means that it can provide higher quality network connections.
• Upgrade to 4096-QAM: In wireless technology, signal modulation is extremely important. The Wi-Fi 6 standard uses 1024-QAM modulation technology, and Wi-Fi 7 is expected to upgrade the modulation method and directly use 4096-QAM, which will expand the transmission data capacity. The final theoretical speed can reach 46.1Gbps, which is 4.8 times the current WiFi 6 speed of 9.6Gbps.
• Multi-AP coordination: This may be a key point in Wi-Fi 7. Regarding the coordination of multiple APs. Currently, in the working mode of 802.11, there is actually no coordination between APs. The coordination defined by some manufacturers is only to optimize the selection of channels to avoid conflicts between APs. The biggest benefit of AP coordination is the distributed MIMO formed between APs. Two different APs can provide MIMO transmission functions for one node, which can greatly improve the efficiency of spatial multiplexing.
• Lower latency: By introducing technologies such as multi-link operation (MLO), multi-AP coordination, and 320MHz bandwidth channels, Wi-Fi 7 latency can be greatly reduced and reliability can be improved. Among them, multi-link operation (MLO) enables devices to transmit and receive across different frequency bands and channels at the same time. Wi-Fi 7 can enhance these links by increasing throughput, which is a measurement of data between devices in a local network (LAN). MLO will also reduce latency and improve reliability.
• Wi-Fi sensing: A big difference between Wi-Fi 7 and its predecessors is the introduction of Wi-Fi sensing. It is reported that Wi-Fi 7 can detect people moving in different rooms without any sensors. The technology is also sensitive enough to even detect the user's breathing rate, "because when they breathe, it changes the RF characteristics and channel characteristics."​