WIFI WMM 协议

© 2012 Wi-Fi Alliance. All Rights Reserved.

Used with the permission of the Wi-Fi Alliance under the terms set forth above.

1

Wi-Fi Alliance

®

Technical Committee 2

WMM

®

11

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This document may be used with the permission of the Wi-Fi Alliance under the terms set forth herein. 14

By your use of the document, you are agreeing to these terms. 15

third parties before making, using or selling the inventions. 25

The Wi-Fi Alliance owns the copyright in this document and reserves all rights therein. A user of this document may 26

duplicate and distribute copies of the document in connection with the authorized uses described herein, provided any 27

permission has been received from the Wi-Fi Alliance, any other use of this document and all other duplication and 29

distribution of this document are prohibited. Unauthorized use, duplication, or distribution is an infringement of the Wi-Fi 30

Alliance’s copyright. 31

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NO REPRESENTATIONS OR WARRANTIES (WHETHER EXPRESS OR IMPLIED) ARE MADE BY THE WI-FI 33

© 2012 Wi-Fi Alliance. All Rights Reserved.

Used with the permission of the Wi-Fi Alliance under the terms as stated in this document.

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Document History 1

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© 2012 Wi-Fi Alliance. All Rights Reserved.

Used with the permission of the Wi-Fi Alliance under the terms as stated in this document.

Page 3 of 45

Contents .......................................................................................................................................... 3 2

List of Figures .................................................................................................................................. 5 3

List of Tables ................................................................................................................................... 6 4

1.0 Overview ............................................................................................................................... 7 5

1.1 References ........................................................................................................................ 7 6

1.2 Terms and Definitions ....................................................................................................... 7 7

1.3 WMM Features .................................................................................................................. 8 8

2.0 WMM Frame Formats ......................................................................................................... 10 9

2.1 Data Frame Formats ....................................................................................................... 10 10

2.1.1 Fields........................................................................................................................ 10 11

2.2.1 WMM Information Element ...................................................................................... 12 18

2.2.2 WMM Parameter Element ....................................................................................... 14 19

2.2.3 Beacon Frame ......................................................................................................... 16 20

2.2.4 Probe Request Frame.............................................................................................. 16 21

2.2.5 Probe Response Frame ........................................................................................... 16 22

2.2.6 Association Request Frame ..................................................................................... 17 23

2.2.7 Association Response Frame .................................................................................. 17 24

2.2.8 Re-Association Request Frame ............................................................................... 17 25

2.2.9 Re-Association Response Frame ............................................................................ 17 26

2.2.10 Management Action Frame ..................................................................................... 17 27

3.2 Setting of WMM Parameters ........................................................................................... 24 34

3.2.1 Default WMM parameters ........................................................................................ 24 35

3.2.2 WMM Parameters in an Infrastructure Network ...................................................... 24 36

3.2.3 WMM Parameters in an IBSS .................................................................................. 24 37

3.3 Assignment of Frames to Queues .................................................................................. 25 38

3.3.1 Mappings for Unicast Frames .................................................................................. 25 39

3.3.2 Mappings for Received Unicast Frames at an AP ................................................... 25 40

3.3.3 Mappings for Group Addressed and Buffered Frames at an AP ............................. 26 41

© 2012 Wi-Fi Alliance. All Rights Reserved.

Used with the permission of the Wi-Fi Alliance under the terms as stated in this document.

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3.4 Channel Access Protocol ................................................................................................ 26 1

3.4.1 Reference Implementation ....................................................................................... 26 2

3.5.1 Admission Control Procedures ................................................................................ 32 9

3.5.2 Procedures at the AP ............................................................................................... 32 10

3.5.3 Procedure at STAs ................................................................................................... 33 11

3.6 WMM-Power Save Procedures ....................................................................................... 34 12

3.6.1 U-APSD General Operation ..................................................................................... 34 13

3.6.2 U-APSD AP Operation ............................................................................................. 35 14

3.6.3 U-APSD STA Operation........................................................................................... 36 15

A.1 QoS Parameter Updates ................................................................................................. 38 16

A.2 Use of Admission Control and Downgrading .................................................................. 38 17

A.3 Deriving Medium Time .................................................................................................... 38 18

A.7.1 AAD Construction with QC ...................................................................................... 41 25

A.7.2 CCM Nonce with Priority Octet ................................................................................ 41 26

A.8 Differences between Legacy DCF Formulation and WMM ............................................. 41 27

A.9 Configuration Procedure (Informative) ............................................................................ 43 28

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© 2012 Wi-Fi Alliance. All Rights Reserved.

Used with the permission of the Wi-Fi Alliance under the terms as stated in this document.

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List of Figures 1

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Figure 1 WMM QoS Data Frame Format ...................................................................................... 10 3

Figure 2 Frame Control Field [1] .................................................................................................... 10 4

Figure 3 Sequence Control Field ................................................................................................... 11 5

Figure 4 QoS Control Field ............................................................................................................ 12 6

Figure 8 WMM Parameter Element ............................................................................................... 14 10

Figure 12 Management Action Frame Format .............................................................................. 17 14

Figure 13 WMM TSPEC Element .................................................................................................. 19 15

Figure 14 WMM TSPEC Body format............................................................................................ 19 16

Figure 15 TS Info Field in WMM TSPEC Element ........................................................................ 20 17

Figure 16 Nominal MSDU Size Field ............................................................................................. 21 18

Figure 17 Reference Implementation Model ................................................................................. 26 19

Figure 18 EDCA Mechanism Timing ............................................................................................. 29 20

Figure 19 TKIP MIC Processing Format ....................................................................................... 39 21

Figure 20 Frame Format with 802.1Q VLAN tag ........................................................................... 40 22

Figure 21 Frame Format without 802.1Q VLAN Tag..................................................................... 40 23

Figure 22 AAD Construction with QC ............................................................................................ 41 24