Wi-Fi 7 In Depth: Your guide to mastering Wi-Fi 7, the 802.11be protocol, and their deployment by unknow

Author:unknow
Language: eng
Format: epub
Publisher: Addison-wesley
Published: 2025-11-15T00:00:00+00:00

Improved estimation of the signal to interference plus noise ratio (SINR) of the trained subcarriers. This improved SINR estimate can be used for better MIMO equalization and decoding, and can provide increased robustness to narrowband interferers.

Spatial suppression of ongoing interference, in the most advanced implementations.

Packet Extension

The Packet (i.e., PPDU) Extension (PE) field is a necessary evil. The PE field carries no data, but provides the receiver with extra time, beyond SIFS, to complete processing of the end of the PPDU. The PE field is a raw waveform that is undefined except for the constraint that its power spectral density (PSD) must closely track the PSD of the Data field so that other wireless devices continue to perceive that the wireless medium is busy.

Because EHT introduces 320 MHz and MCS 12 and MCS 13, the receiver needs extra time to process the increased data load at the end of the PPDU. Accordingly, EHT newly defines a nominal packet padding of 20 μs, in addition to the existing values of 0, 8, and 16 μs.

Recall that the final OFDM symbol in the Data field has the usual length but is considered as four quarters (four symbol segments). One, two, three, or four of the symbol segments carry coded data, and the remaining symbol segments are filled with undefined post-FEC padding bits. A final OFDM symbol with just one quarter of the usual number of coded bits still takes the same time for the FFT and for MIMO equalization, but the time taken for decoding should be reduced by approximately a factor of 4. More broadly, given that the OFDM symbol duration is 16 μs or nearly so, each symbol segment containing post-FEC padding bits nominally reduces the required decoding time by 4 μs.

This characteristic allows the nominal packet padding to be achieved via a mix of post-FEC padding bits and the PE field. Considering a required nominal packet padding of 20 μs, if the final OFDM symbol carries one, two, three, or four symbol segments of coded data, then the PE field’s actual duration is 8, 12, 16, or 20 μs, respectively.

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