Key technology elements of the Wi-Fi 7 standard
The 6 GHz band provides a limited number of 320 MHz channels, with only two overlapping channels in Europe and six in North America, for example. However, now that the 6 GHz band is free for license exempt use, it is now possible to fully leverage the power of Wi-Fi 7. The availability of 160/320 MHz wide channels and the preamble puncturing introduced in Wi-Fi 6 will become increasingly important.
In this context, the introduction of multiple resource units (MRU) becomes relevant to more efficiently use spectrum resources. The optional feature of the next higher modulation scheme, 4096QAM, allows for higher data throughput under optimal radio conditions (high signal to noise ratio), making it most suitable for short range communication between Wi-Fi devices.
MLO will be introduced in different variations. Generally, a multi link device (MLD) can simultaneously establish and operate multiple links on different channels. This improves overall throughput, latency and reliability, especially in a busy radio environment. For this purpose, the MAC layer is divided into upper and lower sublayers: the upper sublayer handles functionalities common across all links, while the lower sublayer handles link specific functionalities.
Depending on the radio capabilities of the MLD, two modes of operation are defined:
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Simultaneous transmit and receive (STR)
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Non simultaneous transmit and receive (NSTR)
Specific operational models are defined for mobile, battery powered devices with limited radio capability. These models include the enhanced multi link single radio (EMLSR) mode for STAs and NSTR mobile AP MLD operation.
