Or only the data field (non-HT/ERP-OFDM). Next after the legacy preamble, it is either the HT/VHT/HE preamble, if the frame is those frame types and the data field. All of the receivers use this information to calculate the duration of time for this full-frame. All stations on the channel read the Rate and Length information subfields and use this for different purposes. The L-SIG field is a symbol where each of the 48 data subcarriers is BPSK modulated. – More accurate frequency offset estimation and time synchronization The receiver uses this waveform after it has detected the L-STF, for: The Legacy Long Training field is also a very specific and unique waveform, but it is different from the L-STF. The receiver uses this waveform, when it detects it, for : The Legacy Short Training field consists of a very specific and unique waveform which are very easy to detect for an 802.11 receiver. The three part of the legacy preamble is and does this: Non-HT (OFDM) or ERP-OFDM (802.11a/802.11g) frame formats consist only of the legacy preamble and the data field. If the data field is sent with MCS data rates, it is either an HT, VHT, or HE frame, and those frame formats have their own preamble right after the legacy preamble. The first part is the legacy preamble consisting of the Legacy Short Training fields (L-STF), the Legacy Long Training fields (L-LTF), and the Legacy Signal field (L-SIG). The preamble is further divided into smaller parts. The preamble is also called the Physical header and it is prepended to the data field, which carries the frame body. The OFDM frame format consists mainly of two parts, the preamble and, the data field. The 5GHz OFDM frame format looks like this: In this article I will write about the uniqueness of the 802.11 preamble, how important it is to detect it and how long it travels The last week’s online discussions has open my eyes to another look at the protocol and the importance of detecting the 802.11 preamble. But it seems my understanding has been wrong. I have in my short WiFi life thought when an 802.11 station (WiFi) does carrier detect it would detect all parts of an ongoing frame transmission on the channel and defer its own transmission because of that.
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