IEEE P802.11
Wireless LANs
Clarification of EDCA Parameter element
Date:	16 Sep. 2003
Primary Author: 
Thomas Kuehnel
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
Tel: (425) 706-4351
Fax: (425) 936-7329
Email: tkuehnel@microsoft.com

Abstract

This submission describes the use of the EDCA Parameter Element and its coding.
Current Spec
7.3.2.14 EDCA Parameter Set element
The EDCA Parameter Set element provides information needed by QSTAs for proper operation of the QoS facility during the contention period.  The format of the EDCA Parameter Set element is defined in Figure 6.
The EDCA Parameter Set element is used by the QAP to establish policy (by changing default MIB values), to change policies when accepting new stations or new traffic, or to adapt to changes in offered load. The most recent EDCA parameter set element received by a QSTA is used to update the appropriate MIB values.

Octets: 1	1	1	1	4	4	4	4	
Element ID (12)	Length (18)	AC Info field	Reserved	AC_BE Parameters Record	AC_BK Parameters Record	AC_VI Parameters Record	AC_VO Parameters Record	
Figure 6 EDCA Parameter Set Element

The EDCA Parameter Set Element contains an AC Info field. The format of the AC Info field is shown in Figure 5. The AC Info field contains the Parameter Set Count, which is initially arbitrary and is incremented each time any of the AC parameters changes. This field can be used by QSTAs to determine whether the EDCA parameter set has changed and requires updating the appropriate MIB values.  The fields following the AC Info field shall be included in multiple beacons following a change in AC parameters to assure that all QSTAs are able to receive the updated EDCA parameters.  The reserved bits are set to 0 upon transmission and shall be ignored upon reception.
The EDCA Parameter Set Element shall be present in selected Beacons, in Association Response frames and in Probe Response frames. A QSTA that does not have the current EDCA Parameter Values based on the Parameter Set Count Value should query the current EDCA Parameter values by sending a probe request to the QAP.

The EDCA Parameter Set Element contains an AC Info field. The format of the AC Info field is shown in Figure 5. The AC Info field contains the Parameter Set Count, which is initially arbitrary and is incremented each time any of the AC parameters changes. This field can be used by QSTAs to determine whether the EDCA parameter set has changed and requires updating the appropriate MIB values.  The fields following the AC Info field shall be included in multiple beacons following a change in AC parameters to assure that all QSTAs are able to receive the updated EDCA parameters.  The reserved bits are set to 0 upon transmission and shall be ignored upon reception.

7.3.2.20 QoS Capability element 

Octets: 1	1	1	
Element ID (46)	Length	AC Info field	
Figure 46.15 QoS Capability element format 

7	6	5	4	3	0	
Q-Ack	Queue Request	TXOP Request	More Data Ack	Parameter Set Count	
Figure 5 AC Info field

The QoS Capability element shall be present in beacons that do not contain the EDCA Parameter Set element, in association request frames, re-association request frames
 In Association Request frames, Re-association Request frames the Parameter set count should be initialized with 0. 

7.2.3.1 Beacon Frame format
Instruct the editor to add a note that the EDCA Parameter element of the QoS parameter shall be present but not both.

7.2.3.5 Association Response frame
Instruct the editor to remove QoS Capability from Table 9.

7.2.3.7 Re-association Response frame
Instruct the editor to remove QoS Capability from Table 10

7.2.3.9 Probe response frame format
Instruct the editor to remove QoS capability element from Table 12.