U-APSD explained and debugged

By sekmo Unpublished


U-APSD is a power-save mechanism that is an optional part of the IEEE amendment 802.11e, QoS. U-APSD is also known as WMM Power Save, and the behaviour and operation is exactly the same, except for coding of some information elements. 


U-APSD is working in conjunction with WMM and is tied with usage of the 4 EDCA access categories that is used to differentiate packets and their priorities. U-APSD is very well suited for bi-directional data flows like voice. 


The power savings is around 400% with Ascom i62 default settings compared to active mode, and extends the talk time from around 4 hours in active to around 16 hours in U-APSD mode with the standard battery.


This attached document aims to explain the logics and behaviour of 802.11 power-save mechanisms and U-APSD as implemented in the Ascom i62. The document will also suggest some methods to debug any anomalies or problems with U-APSD operation.



U-APSD explained and debugged_i62_R2.pdf
1 comment


Jan 04, 2017 04:50 PM

This is a STELLAR document!  Well done.