DEFINITIONS - 17

traffic classification (TCLAS): The specification of certain parameter values to identify the medium access
control (MAC) service data units (MSDUs) belonging to a particular traffic stream (TS). The classification
process, performed above the MAC service access point (MAC_SAP) at a quality-of-service (QoS) access
point (AP), uses the parameter values for a given TS to examine each incoming MSDU and determine
whether this MSDU belongs to that TS. TCLAS might also occur at non-access-point (non-AP) QoS station
(STA) with multiple streams.
NOTE—However, such classification is beyond the scope of this standard.
traffic filter: A set of traffic specifications defined by the use of traffic classification (TCLAS) elements
that are utilized by the traffic filtering service (TFS) to identify specific allowed frames.
traffic filtering service (TFS): A service provided by an access point (AP) to a non-AP station (STA) to
reduce the number of frames sent to the non-AP STA by not forwarding individually addressed frames
addressed to the non-AP STA that do not match traffic filters specified by the non-AP STA.
traffic identifier (TID): Any of the identifiers usable by higher layer entities to distinguish medium access
control (MAC) service data units (MSDUs) to MAC entities that support quality of service (QoS) within the
MAC data service. There are 16 possible TID values; eight identify TCs, and the other eight identify
parameterized TSs. The TID is assigned to an MSDU in the layers above the MAC.
traffic indication map (TIM) broadcast: A service that enables a non-access-point (non-AP) station
(STA) to request periodic transmission of a TIM frame by the AP. TIM frames have shorter duration than
Beacon frames and can be transmitted at a higher physical layer (PHY) rate, which allows the STA to save
additional power while periodically checking for buffered traffic in standby mode, relative to the power
consumed if the station (STA) were to periodically wake up to receive a beacon frame.
traffic specification (TSPEC): The quality-of-service (QoS) characteristics of a data flow to and from a
QoS station (STA).
traffic stream (TS): A set of medium access control (MAC) service data units (MSDUs) to be delivered
subject to the quality-of-service (QoS) parameter values provided to the MAC in a particular traffic
specification (TSPEC). TSs are meaningful only to MAC entities that support QoS within the MAC data
service. These MAC entities determine the TSPEC applicable for delivery of MSDUs belonging to a
particular TS using the priority parameter provided with those MSDUs at the MAC service access point
(MAC_SAP).
traffic stream identifier (TSID): Any of the identifiers usable by higher layer entities to distinguish
medium access control (MAC) service data units (MSDUs) to MAC entities for parameterized quality of
service (QoS) [i.e., the traffic stream (TS) with a particular traffic specification (TSPEC)] within the MAC
data service. The TSID is assigned to an MSDU in the layers above the MAC.
transmission opportunity (TXOP): An interval of time when a particular quality-of-service (QoS) station
(STA) has the right to initiate frame exchange sequences onto the wireless medium (WM). A TXOP is
defined by a starting time and a maximum duration. The TXOP is either obtained by the STA by
successfully contending for the channel or assigned by the hybrid coordinator (HC).
transmission opportunity (TXOP) holder: A quality-of-service (QoS) station (STA) that has either been
granted a TXOP by the hybrid coordinator (HC) or successfully contended for a TXOP.
transmission opportunity (TXOP) responder: A station (STA) that transmits a frame in response to a
frame received from a TXOP holder during a frame exchange sequence, but that does not acquire a TXOP in
the process.