Wi-Fi Gets Wider With Wi-Fi 7

The last 56k dialup modem I bought in 1998 cost more than double the price of a 28k modem, and the double bandwidth was worth the extra money. New Wi-Fi 7 devices are similarly premium-priced because early adaptation of leading-edge new technology is nearly always expensive. The 6 GHz Wi-Fi band was introduced in 2020 as Wi-Fi 6E (aka IEEE 802.11ax) and it covers from 5.925 to 7.125 GHz. Recently introduced Wi-Fi 7 (aka IEEE 802.11be) is the first standard to actively aggregate the new 6 GHz band with the 2.4, and 5 GHz bands.

The term Wi-Fi was a pre-Y2K, consumer-friendly marketing term for IEEE.802.11. Wi-Fi later became a trademark of the Wi-Fi Alliance. Wi-Fi 4, aka 802.11n, was the first numbered Wi-Fi generation, introduced in 2008. Final acceptance of Wi-Fi 7 isn’t expected until later this year, but the technical requirements are essentially locked in, and new products are available on the market.

If you’ve used Wi-Fi for video and audio transport you are probably familiar with the differences between 2.4 GHz and 5 GHz Wi-Fi. The 2.4 GHz band has 14 channels. It is capable of longer range, but 2.4 GHz is very crowded with baby monitors and security devices, which can be challenging for professional video transport over a distance. 5 GHz Wi-Fi has 42 channels of up to nineteen, 5 GHz channels. Wi-Fi 6E, introduced in 2020, is the predecessor of the Wi-Fi 7. Wi-Fi 6E provides seven 160 MHz channels with speeds up to approximately 1 GHz.

The big news about Wi-Fi 6E is that it uses 1024 quadrature amplitude modulation (1024-QAM) encoding and uses orthogonal frequency division multiple access (OFDMA) to share channels. OFDMA is not backward compatible. When a Wi-Fi 7 router senses a network device using Wi-Fi 4, for example, it uses that standard’s capabilities. Wi-Fi 7 can help, but only when everything on the network is operating on Wi-Fi 7.

The problem with the 6GHz wireless spectrum is that it uses shorter wavelengths that work best at short distances free of physical obstructions. If you ever worked at a TV station on UHF channel 35 or higher, you’ve learned from viewers about common occurrences like dew on tree leaves that can attenuate a relatively strong high-power UHF TV signal. The wavelength of a 600 MHz signal (formerly TV Channel 49) is 0.5 meters. The wavelength of a 6 GHz signal is 1% of a 600 MHz signal; 0.05 meters (50mm). Most unlicensed Wi-Fi systems radiate signals less than one watt ERP. Wi-Fi 8, anticipated for 2028 release will include mmWave frequencies and channels with wider bandwidths, which will be significantly more susceptible to natural attenuation by atmospherics and physical obstructions.

Why Wi-Fi 7?

Wi-Fi 7 (IEEE 802.11be) operates across 2.4, 5 and 6 GHz bands to deliver high speeds to every device. Wi-Fi 7 uses Multi-Link Operation (MLO) to increase capacity by simultaneously transmitting and receiving data across different Wi-Fi bands and channels. With MLO, Wi-Fi 7 devices can simultaneously connect to the network on two bands for faster speeds through aggregation or for redundant data. MLO controls the router. Wi-Fi 7 also doubles the number of multi-user, multiple-input and multiple-out (MU-MIMO) spatial streams to and from other devices. Wi-Fi 6 supports 8x8 MU-MIMO. Wi-Fi 7 can support 16x16, but gear so far most Wi-Fi 7 solutions only support 4x4 or 2x2 MU-MIMO. The number of MU-MIMO streams a router is capable of is revealed by counting its built-in antennas.

Wi-Fi 7 boasts an extremely high throughput of 46 Gbps, although most video transport application users report up to about one Gbps of useable bandwidth. The high throughput is most advantageous when communicating with dozens or hundreds of Wi-Fi connected devices, such as audiences in auditoriums, theaters, and stadiums. Wi-Fi 7 uses 4096-QAM (aka 4K-QAM) which enables a 20% data rate increase in Wi-Fi 7 compared to the 1024-Qam Wi-Fi 6 (IEEE 802.11ax). 4K-QAM is the key to reliable service for large numbers of high-speed clients in high-density venues.

The 2.4 GHz band is 100MHz of spectrum between 2.4 and 2.5 GHz. It provides 14 channels each 20 MHz wide. Only four 2.4 GHz band channels are non-overlapping. The 5 GHz band spectrum is 150 MHz wide, and it provides 24 non-overlapping 20 MHz channels. There’s a greater chance of interference and congestion on channels wider than 20 MHz. On the 5 GHz band, channel widths can be from 20-160 MHz, but congestion across that much shared spectrum can be a limiting issue. The 6 GHz Wi-Fi band is 1200 MHz wide and can accommodate channels up to 320 MHz wide. The good and bad news about the 6GHz band is that its short range makes its overlapping channels less susceptible to outside interference through walls and floors.

In legacy Wi-Fi 6/6E Wi-Fi, if any part of a high-speed channel is used by another device, the entire channel becomes unavailable. Wi-Fi 7 uses ‘Multi Resource Units (RU) and Puncturing’ to enable high-speed channel sharing of unused bandwidth in 5 and 6 GHz band high-speed channels. Wi-Fi 7 also introduces Multi-Link Operation (MLO) & Deterministic Latency to achieve consistent low latency in Wi-Fi networks.

Why Wi-Fi 6E?

Researching the latest marketing information indicates that Wi-Fi 7 is purposely designed to simultaneously handle large numbers of client devices. The unique advantage of Wi-Fi 6E and Wi-Fi 7 is the 1200 MHz wide, 600 GHz band with 320 MHz channels. For video transport within a video production facility or TV station, Wi-Fi 6E may be a better solution than Wi-Fi 7 because it costs less and has been on the market for nearly four years. The advantages of Wi-Fi 7 will become ubiquitous in TV facilities when prices of Wi-Fi 7 certified gear become more affordable.

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