Uniform 802.11e Admissions Control Signaling for HCF and EDCF

1. Uniform 802.11e Admissions Control Signaling for HCF and EDCF Bob Meier, Liwen Wu, Mark Bilstad Cisco Systems November 11, 2002 bilstad@cisco.com Mark Bilstad, Cisco Systems

2. Considerations/Issues • There is a recognized need for Explicit Admissions Control Signaling, independent of the access method • Explicit EDCF Admissions Control enables infrastructure policy and policing. • For example, it may be desirable to limit QoS bandwidth for “guest” users in an enterprise network. Mark Bilstad, Cisco Systems

3. Considerations/Issues • Explicit admissions control is not useful unless all QSTAs participate • A method is needed for a WSTA to determine whether explicit admissions control is required • The current TSPEC Status Codes are insufficient. A QSTA cannot determine if a TSPEC is rejected because 1) resources are not available, or 2) HCF Polling is not enabled for the traffic type. Mark Bilstad, Cisco Systems

4. Summary of proposed changes • TSPEC • Add Access Method bits to TSinfo field of TSPEC IE • Add new TSPEC status code • Delete text that prohibits EDCF access for stations with admitted TSPECs • Add 8 new flags to QoS Parameter Set IE to indicate when explicit vs. distributed admissions control is in use per user priority Mark Bilstad, Cisco Systems

5. B13 B14 Polled access Contention-based access 1 1 Allocate 2 bits in the TSPEC TSInfo Field in Figure 42.8 • QSTA indicates its capabilities in the ADDTS request • HC responds with what will be used in the ADDTS response Mark Bilstad, Cisco Systems

6. Add text to section 7.3.2.15 A QSTA sets the TSInfo “Access” fields in an ADDTS request to indicate to the HC the access methods that it will accept for the traffic stream and to indicate its access method capabilities. The fields are set in an ADDTS Request as follows: The Polled Access field is set to 1 if the QSTA will accept access via HCF polling. The Contention-based Access field is set to 1 if the QSTA will accept EDCF as the access method. An HC uses the TSInfo “Access” fields in an ADDTS Response to establish the access method used for the traffic stream for an accepted TSPEC. The HC cannot establish an access method where the QSTA has indicated that it will NOT accept the access method. The HC sets exactly one of these bits to 1 to indicate which type of access has been accepted for the request. Mark Bilstad, Cisco Systems

7. Remove restrictions in text • Delete the following paragraph in 9.10.2.3: “HCF contention-based channel access shall not be used to transmit MSDUs belonging to traffic streams for which the traffic specification as furnished to/by the HC has a specified minimum data rate and a specified delay bound, except as may be necessary to obtain the first polled TXOP from the HC for a newly added or modified traffic stream.” Mark Bilstad, Cisco Systems

8. New TSPEC Status Code Table 20.5 – Status Codes Mark Bilstad, Cisco Systems

9. Octets: 1 1 2 42 2 Element ID(12) Length(46) QoS Parameter Set Count (existing) b0..b7: ExplicitAdmCtrl[UP] Add 8 flags tothe QoS Parameter Set • AP sets flag to 1 when explicit admissions control is required for the respective user priority Mark Bilstad, Cisco Systems

10. Other considerations • For explicit admissions control, TXOPBudget can be used by roaming WSTA to predict whether a TSPEC is likely to be admitted • Flow-specific access parameters (CWmin, CWmax, AIFS, TXOPlimit) can be returned in the ADDTS response Mark Bilstad, Cisco Systems

11. Octets: 1 1 1 1 2 2 Element ID (TBD) Length(6) AIFS value CWmin value CWmax value TXOPLimit New Access Parameters IE • Flow-specific uplink access parameters are returned in the ADDTS response Mark Bilstad, Cisco Systems