Determination of UP

5.1.1.2 Determination of UP

The QoS facility supports eight priority values, referred to as UPs. The values a UP may take are the integer
values from 0 to 7 and are identical to the IEEE 802.1D priority tags. An MSDU with a particular UP is said
to belong to a traffic category (TC) with that UP. The UP is provided with each MSDU at the medium access
control service access point (MAC_SAP) either directly, in the UP parameter, or indirectly, in a TSPEC
designated by the UP parameter.
5.1.1.3 Determination of UP of received frames at the AP sent by other STAs in the BSS
The received individually addressed frames at the AP may be as follows:
a) Non-QoS subtypes, in which case the AP shall assign to them a priority of Contention, if they are
received during the contention period (CP), or ContentionFree, if they are received during the
contention-free period (CFP).
b) QoS subtypes, in which case the AP shall infer the UP value from the TID in the QoS Control field
directly for TID values between 0 and 7. For TID values between 8 and 15 the AP shall extract the

UP value in the UP subfield of the TS Info field in the associated TSPEC or from the UP field in the
associated TCLAS (traffic classification) element, as applicable.
QoS APs deliver the UP with the received MSDUs to the DS.
5.1.1.4 Interpretation of priority parameter in MAC service primitives
The value of the priority parameter in the MAC service primitives (see 5.2) may be a noninteger value of
either Contention or ContentionFree or may be any integer value in the range 0 to 15.
When the priority parameter has an integer value, it is used in the TID subfields that appear in certain frames
that are used to deliver and to control the delivery of QoS data across the WM.
Priority parameter and TID subfield values 0 to 7 are interpreted as UPs for the MSDUs. Outgoing MSDUs
with UP values 0 to 7 are handled by MAC entities at STAs in accordance with the UP.
Priority parameter and TID subfield values 8 to 15 specify TIDs that are also TS identifiers (TSIDs) and
select the TSPEC for the TS designated by the TID. Outgoing MSDUs with priority parameter values 8 to 15
are handled by MAC entities at STAs in accordance with the UP value determined from the UP subfield as
well as other parameter values in the selected TSPEC. When an MSDU arrives with a priority value between
8 and 15 and for which there is no TSPEC defined, then the MSDU shall be sent with priority parameter set
to 0.
The noninteger values of the priority parameter are allowed at all non-QoS STAs. The use of priority value
of ContentionFree is deprecated at QoS STAs. The integer values of the priority parameter (i.e., TID) are
supported only at QoS STAs that are either associated in an infrastructure QoS BSS or members of a QoS
IBSS. A range of 0 to 15 is supported by QoS STAs associated in a QoS BSS; whereas a range of 0 to 7 is
supported by QoS STAs that are members of a QoS IBSS. If a QoS STA is associated in a non-QoS BSS, the
STA is functioning as a non-QoS STA, so the priority value is always Contention or ContentionFree.
At QoS STAs associated in a QoS BSS, MSDUs with a priority of Contention are considered equivalent to
MSDUs with TID 0, and those with a priority of ContentionFree are delivered using the contention-free
delivery if a point coordinator (PC) is present in the AP. If a PC is not present, MSDUs with a priority of
ContentionFree shall be delivered using an UP of 0. At STAs associated in a non-QoS BSS, all MSDUs with
an integer priority are considered equivalent to MSDUs with a priority of Contention.
If a STA is associated in a QoS BSS, the MSDUs it receives in QoS data frames are reported with the TID
value contained in the MAC header of that frame. The MSDUs such a STA receives in non-QoS data frames
are reported to LLC with a priority of Contention, if they are received during the CP, or ContentionFree, if
they are received during the CFP.