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Changes between Version 6 and Version 7 of 802.11/PacketFlow

v6	v7
27	27	[[Image(wiki:802.11/files:wlan_ref_des_pkt_buf_offsets.png,height=300)]]
28	28
29		The MAC code utilizes the first section of each packet buffer for metadata about the packet contained in that buffer. This metadata is stored in the {{{tx_frame_info}}} and {{{rx_frame_info}}} structs, defined in ~~wlan_lib.h~~.
	29	The MAC code utilizes the first section of each packet buffer for metadata about the packet contained in that buffer. This metadata is stored in the {{{tx_frame_info}}} and {{{rx_frame_info}}} structs, defined in [source:ReferenceDesigns/w3_802.11/c/wlan_mac_common/include/wlan_mac_misc_util.h wlan_mac_misc_util.h]. This metadata includes the per-subcarrier channel estimates from the RX PHY.
30	30
31	31	The second section is the PHY header. For Tx packets the MAC must populate this section with a valid SIGNAL field. When a new transmission is initiated the Tx PHY will read these bytes first to determine the modulation/coding rates and payload length. The Tx PHY will terminate immediately if the SIGNAL bytes are invalid. For Rx packets the PHY will write the raw SIGNAL field bytes to the PHY header area. This is useful for debugging; for normal Rx processing the MAC will be notified of the Rx length and rate via registers in the DCF MAC core.