Monday, February 15, 2016

WiFi: PP-AMSDU versus SPP-AMSDU a brief comparison

Before we jump into the different type of AMSDUs supported, let us do a quick recap of where AMSDUs fit in with the aggregation hierarchy. Here is an image from Wikipedia:
MSDU, MPDU and PPDU
Multiple MSDUs aggregate to form an AMSDU. Multiple of these will form an AMPDU. The different type of AMSDUs are defined in the WGs documents:
3.114n Payload Protected A-MSDU (PP A-MSDU): An A-MSDU that is CCMP protected but does not include the A-MSDU Present field (bit 7 of the QoS control field) in the construction of the AAD. 
3.135n Signaling and Payload Protected A-MSDU (SPP A-MSDU): An A-MSDU that is CCMP protected and does include the A-MSDU Present field (bit 7 of the Qos control field) in the construction of the AAD.