Trigger frames adapted to packet-based policies in an 802.11 network
摘要
說明書
This is also because, even for the same type of data traffic or for the same quantity of data to transmit, the modulation used by the nodes (the modulation is linked to the distance between the transmitting node and the Access Point) substantially modifies the transmission duration. According to the modulation used (MCS0 to 9 in IEEE802.11ac), the number of bit carried by each OFDM symbol changes, and for a given quantity of data, the transmission duration changes also knowing that the symbol duration is fixed.
For instance, node STA1 may transmit web browsing traffic (AC_BE: access category best effort), node STA2 may transmit a control frame, and node STA4 may transmit a large aggregation of video data frames (AC_VI: access category Video).
As shown in the Figure, the PPDU sent by STA4 (553) use the full TXOP duration of the UL MU OFDMA while the PPDU send by STA1 (551) requires padding (552) to maintain a signal on the RU #1 for the entire TXOP duration. Indeed, if the data transmission lasts less than the TXOP duration 550, the nodes have to pad up (send padding data) up to the end of the UL MU transmission.
This example of
The so-called “small packets” as the one sent by STAT suffer from important overhead, due to the important amount of padding required to have a signal up to the end of TXOP 230. There is a need to mitigate this situation and to improve efficiency of the Trigger Frame mechanism when small packets are transmitted.
