Trigger frames adapted to packet-based policies in an 802.11 network
摘要
說明書
In practice, the source node 20 has one transmitting buffer queue for each access category and thus implements a backoff counter for each access category. The backoff counter having the lowest value from among the four AC backoff counter is considered as being the backoff counter for the node as discussed above, since it is the first one to reach zero.
An ACK frame 240 is sent by the receiving node 21 after having correctly received the data frames sent, after a new SIFS time period 27.
If the source node 20 does not receive the ACK 240 within a specified ACK Timeout (generally within the TXOP), or if it detects the transmission of a different frame on the radio medium, it reschedules the frame transmission using the backoff procedure anew.
Since the RTS/CTS four-way handshaking mechanism 210/220 is optional in the 802.11 standard, it is possible for the source node 20 to send data frames 230 immediately upon its backoff time counter reaching zero (i.e. at T1).
The requested time duration for transmission defined in the RTS and CTS frames defines the length of the granted transmission opportunity TXOP, and can be read by any listening node (“other nodes 22” in
