Free time after work. This article briefly summarizes the PHY (physical layer) frame format in each version of the Wi-Fi protocol obtained from various web page browsing. The existing WI-FI protocol mainly provides its own history of changes for the MAC layer and the PHY layer. The PHY layer is mainly organized here for reference only. If you have any questions, please feel free to raise them.
The 802.11 protocols of the PHY layer mainly include 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, and 802.11ax.
Figure 1 below shows the PHY frame structure of 802.11a.
As shown in Figure 2, the PHY frame format (HT) in the 802.11n protocol is given.
The detailed structure of the Mixed frame format is shown in Figure 3 below.
The Green Field (green field mode) frame format is described in detail in Figure 4 below.
The explanation of individual fields in the frame is given below:
L-STF: Legacy Short Training Field legacy short training field
L-LTF: Legacy Long Training Field legacy long training field
L-SIG: Legacy Signal Field legacy signal field
HT-SIG : High Throughput Signal Field
HT-LTF1: High Throughput Long Training Field 1
HT-LTF1: High Throughput Long Training Field HT-LTF1: High Throughput Long Training Field
As shown in Figure 5, the PHY frame format (VHT) in the 802.11ac protocol is given.
The latest 802.11ax is an evolved version of ac, and the latest draft protocol download still requires certain permissions. Based on the available information, let's first get a general understanding of ax.
802.11ax is a high-efficiency (HE: High Efficiency) protocol that focuses on achieving an average user throughput 4 times higher than ac in a high-density deployment environment. The new technologies introduced by 802.11ax mainly include:
1. Higher modulation mode (1024QAM)
2. More FFT points
3. Narrower subcarrier spacing
4. Uplink and downlink OFDMA technology
5. Uplink and downlink MU-MIMO technology
6. Spatial reuse technology
to be continued…