WiFi WMM详解

一. WMM 基础

1. 什么是WMM

   

2. Priority mapping table , EDCA Prameter

                               802.1D与802.11E优先级映射

   Priority	UP（Same as 802.1D user Priority）	802.1D designation	AC	Designation （informative）
   Lowest Highest	1	BK	AC_BK	Background
   2	-	AC_BK	Background
   BE	AC_BE	Best Effort
   3	EE	AC_BE	Best Effort
   4	CL	AC_VI	Video
   5	VI	AC_VI	Video
   6	VO	AC_VO	Voice
   7	NC	AC_VO	Voice

                                                                                           信道竞争参数

   AC	CWmin	CWmax	AIFSN	TXOP Limit（802.11b）	TXOP Limit（802.11a/g）
   AC_BK	aCWmin	aCWmax	7
   AC_BE	aCWmin	aCWmax	3
   AC_VI	（aCWmin+1）/2-1	aCWmin	2	6.016ms	3.008ms
   AC_VO	（aCWmin+1）/4-1	（aCWmin+1）/2-1	2	3.264ms	1.504ms

3. WMM Information Element (include in probe request/association request)

   

4. WMM Parameter Element (include in probe response/association response/beacon)

   

5. QoS Data(include QoS Control Field)

   

二. RTP Transfer

1. Packet format(user priority in IP Header Diff Services[7:5])

   

2. user priority为voice的802.11 mac header