WiFi WMM詳解

一. WMM 基礎

1. 什麼是WMM
2. Priority mapping table , EDCA Prameter

                               802.1D與802.11E優先級映射

   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

   0

   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

                                                                                           信道競爭參數

   AC	CWmin	CWmax	AIFSN	TXOP Limit（802.11b）	TXOP Limit（802.11a/g）
   AC_BK	aCWmin	aCWmax	7	0	0
   AC_BE	aCWmin	aCWmax	3	0	0
   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爲voice的802.11 mac header