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Hello, I am trying to modify the MAC and PHY layers of Mango 802.11 reference design. I want to set the modulation mode and code rate fixed. But this involves the length of the MAC frame. How is the MAC frame packed into a PHY frame? Is a MAC frame truncated by a fixed length and packed into a PHY frame?
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You can set the data rate (modulation + coding rates) without modifying the overall MAC and PHY design. The upper MAC sets the data rate of each transmitted packet at run time. The defaults are set in the top-level MAC C code (wlan_mac_ap.c for example). You can also set the rate via the wlan_exp Python framework. Refer to any of our wlan_exp examples for details.
How is the MAC frame packed into a PHY frame? Is a MAC frame truncated by a fixed length and packed into a PHY frame?
The PHY adds a short header in front of the MAC frame, consisting of the 24-bit SIGNAL field and 16-bit SERVICE field. The SIGNAL field specifies the PHY modulation/code rate and the MAC payload length. The PHY always transmits the full payload provided by the MAC - there is no truncation or segmentation at the MAC-PHY interface.
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