Content for TS 24.301 Word version: 18.7.0
3 Definitions and abbreviations p. 26
3.1 Definitions p. 26
For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
The term "mobile station" (MS) in the present document is synonymous with the term "user equipment" (UE) as defined in TR 21.905.
1x CS fallback capable UE:
A UE that uses a CS infrastructure for a voice call and other CS-domain services by falling back to cdma2000® 1x access network if the UE is served by E-UTRAN when a CS service is requested.
Aggregate maximum bit rate:
The maximum bit rate that limits the aggregate bit rate of a set of non-GBR bearers of a UE. Definition derived from TS 23.401.
APN based congestion control:
Congestion control in session management where the network can reject session management requests from UEs or deactivate PDN connections when the associated APN is congested.
Attached for emergency bearer services:
A UE is attached for emergency bearer services if it has only a PDN connection for emergency bearer services established.
Attached for access to RLOS:
A UE is attached for access to RLOS if the UE requested access to RLOS during the attach procedure and has a PDN connection for RLOS established after completion of attach procedure.
Attached for EPS services with CP CIoT EPS optimization:
A UE supporting CIoT EPS optimizations is attached for EPS services, and control plane CIoT EPS optimization along with one or more other CIoT EPS optimizations have been accepted by the network.
Attached for EPS services with User plane CIoT EPS optimization:
A UE supporting CIoT EPS optimizations is attached for EPS services, and user plane CIoT EPS optimization along with one or more other CIoT EPS optimizations have been accepted by the network.
Attached for EPS services with CIoT EPS optimization:
A UE is attached for EPS services with CP CIoT EPS optimization or attached for EPS services with user plane CIoT EPS optimization.
Chosen PLMN:
The same as selected PLMN as specified in TS 23.122.
Control plane CIoT EPS optimization:
signalling optimizations to enable efficient transport of user data (IP, non-IP, Ethernet or SMS) over control plane via the MME including optional header compression of IP data.
CS fallback cancellation request:
A request received from the MM sublayer to cancel a mobile originating CS fallback.
CS fallback capable UE:
A UE that uses a CS infrastructure for a voice call and other CS-domain services by falling back to A/Gb or Iu mode if the UE is served by E-UTRAN when a CS service is requested.
CSG cell:
A cell in which only members of the CSG can get normal service. Depending on local regulation, the CSG cell can provide emergency bearer services also to subscribers who are not member of the CSG. Definition derived from TS 23.401.
CSG ID:
A CSG ID is a unique identifier within the scope of one PLMN defined in TS 23.003 which identifies a Closed Subscriber Group (CSG) in the PLMN associated with a cell or group of cells to which access is restricted to members of the CSG.
CSG selection:
A UE supporting CSG selection selects CSG cell either automatically based on the list of allowed CSG identities or manually based on user selection of CSG on indication of list of available CSGs. Definition derived from TS 23.122.
Current TAI: A TAI of a selected PLMN broadcast in the cell on which the UE is camping. If the cell is a satellite E-UTRA cell broadcasting multiple TACs of the selected PLMN, the UE NAS layer selects the TAI from these multiple TACs of the selected PLMN as specified in clause 4.11.3.
Dedicated bearer:
An EPS bearer that is associated with uplink packet filters in the UE and downlink packet filters in the PDN GW where the filters only match certain packets. Definition derived from TS 23.401.
Default bearer:
An EPS bearer that gets established with every new PDN connection. Its context remains established throughout the lifetime of that PDN connection. A default EPS bearer is a non-GBR bearer. Definition derived from TS 23.401.
Emergency EPS bearer context:
A default EPS bearer context activated with request type "emergency" or "handover of emergency bearer services", or any dedicated EPS bearer context associated to this default EPS bearer context.
EMM context:
An EMM context is established in the UE and the MME when an attach procedure is successfully completed.
EMM-CONNECTED mode:
A UE is in EMM-CONNECTED mode when a NAS signalling connection between UE and network is established or after indication from the lower layers that the RRC connection has been resumed when the UE was in EMM-IDLE mode with suspend indication. The term EMM-CONNECTED mode used in the present document corresponds to the term ECM-CONNECTED state used in TS 23.401.
EMM-IDLE mode:
A UE is in EMM-IDLE mode when no NAS signalling connection between UE and network exists or when RRC connection suspend has been indicated by lower layers. The term EMM-IDLE mode used in the present document corresponds to the term ECM-IDLE state used in TS 23.401.
EPS security context:
In the present specification, EPS security context is used as a synonym for EPS NAS security context specified in TS 33.401.
EPS services:
Services provided by PS domain. Within the context of this specification, EPS services is used as a synonym for GPRS services in TS 24.008.
Evolved packet core network:
The successor to the 3GPP Release 7 packet-switched core network, developed by 3GPP within the framework of the 3GPP System Architecture Evolution (SAE).
Evolved packet system:
The evolved packet system (EPS) or evolved 3GPP packet-switched domain consists of the evolved packet core network and the evolved universal terrestrial radio access network. Definition derived from TS 23.401.
GBR bearer:
An EPS bearer that uses dedicated network resources related to a guaranteed bit rate (GBR) value, which are permanently allocated at EPS bearer establishment/modification. Definition derived from TS 23.401.
General NAS level mobility management congestion control:
The type of congestion control that is applied at a general overload or congestion situation in the network, e.g. lack of processing resources.
Group specific session management congestion control:
Type of congestion control at session management level that is applied to reject session management requests from UEs belonging to a particular group when one or more group congestion criteria as specified in TS 23.401 are met.
Highest ranked ACDC category:
The ACDC category with the lowest value as defined in TS 24.105.
Initial NAS message:
A NAS message is considered as an initial NAS message, if this NAS message can trigger the establishment of a NAS signalling connection. For instance, the ATTACH REQUEST message is an initial NAS message.
In NB-S1 mode:
Indicates this paragraph applies only to a system which operates in NB-S1 mode. For a multi-access system this case applies if the current serving radio access network or the current serving satellite access network provides access to network services via E-UTRA by NB-IoT (see TS 36.300, TS 36.331, TS 36.306).
In WB-S1 mode:
Indicates this paragraph applies only to a system which operates in WB-S1 mode. For a multi-access system this case applies if the system operates in S1 mode, but not in NB-S1 mode. WB-S1 mode also includes satellite access.
In WB-S1/CE mode:
Indicates this paragraph applies only when a UE, which is a CE mode B capable UE (see TS 36.306), is operating in CE mode A or B in WB-S1 mode.
IPv4v6 capability:
Capability of the IP stack associated with a UE to support a dual stack configuration with both an IPv4 address and an IPv6 address allocated.
Kilobit:
1000 bits.
Last Visited Registered TAI:
A TAI which is contained in the TAI list that the UE registered to the network and which identifies the tracking area last visited by the UE. If the cell is a satellite cell broadcasting multiple TAIs, a TAI which is contained in the TAI list that the UE registered to the network and last selected by the UE as the current TAI.
Linked Bearer Identity:
This identity indicates to which default bearer the additional bearer resource is linked.
LIPA PDN connection:
A PDN connection, for which the default EPS bearer context or default PDP context was activated with an APN authorized to use LIPA. The network authorizes an APN for using LIPA based on the subscription profile (see TS 29.272) and subsequently the network considers this PDN connection a LIPA PDN connection.
Lower layer failure:
A failure reported by the AS to the NAS that cannot be corrected on AS level. When the AS indicates a lower layer failure to NAS, the NAS signalling connection is not available.
Mapped EPS security context:
A mapped security context to be used in EPS. Definition derived from TS 33.401.
Mapped GUTI:8
A GUTI which is mapped from a P-TMSI and an RAI allocated previously by an SGSN or a 5G-GUTI previously allocated by an AMF. Mapping rules are defined in TS 23.003. Definition derived from TS 23.401.
Megabit:
1,000,000 bits.
Message header:
A standard L3 message header as defined in TS 24.007.
MME area:
An area containing tracking areas served by an MME.
MO MMTEL voice call is started:
the MO-MMTEL-voice-started indication was received from upper layers (see TS 24.173) and after reception of the MO-MMTEL-voice-started indication, the MO-MMTEL-voice-ended indication has not been received.
MO MMTEL video call is started:
the MO-MMTEL-video-started indication was received from upper layers (see TS 24.173) and after reception of the MO-MMTEL-video-started indication, the MO-MMTEL-video-ended indication has not been received.
MT MMTEL voice call is started:
the MT-MMTEL-voice-started indication was received from upper layers (see TS 24.173) and after reception of the MT-MMTEL-voice-started indication, the MT-MMTEL-voice-ended indication has not been received.
MT MMTEL video call is started:
the MT-MMTEL-video-started indication was received from upper layers (see TS 24.173) and after reception of the MT-MMTEL-video-started indication, the MT-MMTEL-video-ended indication has not been received.MO SMSoIP is started: the MO-SMSoIP-attempt-started indication was received from upper layers (see TS 24.341) and after reception of the MO-SMSoIP-attempt-started indication, the MO-SMSoIP-attempt-ended indication has not been received.
MT SMSoIP is started:
the MT-SMSoIP-attempt-started indication was received from upper layers (see TS 24.341) and after reception of the MT-SMSoIP-attempt-started indication, the MT-SMSoIP-attempt-ended indication has not been received.
MUSIM UE:
A UE with multiple valid USIMs, capable of initiating and maintaining simultaneous separate registration states with PLMN(s) using identities and credentials associated with those USIMs and supporting one or more of the NAS signalling connection release, the paging indication for voice services, the reject paging request, the paging restriction and the paging timing collision control.
NAS level mobility management congestion control:
Congestion control mechanism in the network in mobility management. "NAS level mobility management congestion control" consists of "subscribed APN based congestion control" and "general NAS level mobility management congestion control".
NAS signalling connection:
A peer to peer S1 mode connection between UE and MME. A NAS signalling connection consists of the concatenation of an RRC connection via the "LTE-Uu" interface and an S1AP connection via the S1 interface. Additionally, for the purpose of optimized handover or idle mode mobility from cdma2000® HRPD access to E-UTRAN (see TS 23.402), the NAS signalling connection can consist of a concatenation of an S101-AP connection and a signalling tunnel over a cdma2000® HRPD access network.
NAS signalling connection recovery:
A mechanism initiated by the NAS to restore the NAS signalling connection on indication of "RRC connection failure" by the lower layers.
Native GUTI:
A GUTI previously allocated by an MME. Definition derived from TS 23.401.
Non-access stratum protocols:
The protocols between UE and MSC or SGSN that are not terminated in the UTRAN, and the protocols between UE and MME that are not terminated in the E-UTRAN. Definition derived from TR 21.905.
Non-emergency EPS bearer context:
Any EPS bearer context which is not an emergency EPS bearer context.
Non-EPS services:
Services provided by CS domain. Within the context of this specification, non-EPS services is used as a synonym for non-GPRS services in TS 24.008. A UE which camps on E-UTRAN can attach to both EPS services and non-EPS services.
Non-GBR bearer:
An EPS bearer that uses network resources that are not related to a guaranteed bit rate (GBR) value. Definition derived from TS 23.401.
PDN address:
An IP address assigned to the UE by the Packet Data Network Gateway (PDN GW).
PDN connection for emergency bearer services:
A PDN connection with an emergency EPS bearer context or with a default PDP context activated with request type "emergency" or "handover of emergency bearer services".
PDN connection for RLOS:
A PDN connection for which the default EPS bearer context was activated with request type "RLOS".
Plain NAS message:
A NAS message with a header including neither a message authentication code nor a sequence number.
Persistent EPS bearer context:
either a non-emergency EPS bearer context representing a GBR bearer with QoS equivalent to QoS of teleservice 11 and where there is a radio bearer associated with that context, or an emergency EPS bearer context where there is a radio bearer associated with that context.
Procedure Transaction Identity:
An identity which is dynamically allocated by the UE for the UE requested ESM procedures. The procedure transaction identity is released when the procedure is completed.
RAT-related TMSI:
When the UE is camping on an E-UTRAN cell, the RAT-related TMSI is the GUTI; when it is camping on a GERAN or UTRAN cell, the RAT-related TMSI is the P-TMSI.
Registered PLMN:
The PLMN on which the UE is registered. The identity of the registered PLMN is provided to the UE within the GUTI.
Relay node:
A network element in the E-UTRAN, wirelessly connected to an eNode B and providing relaying function to UEs served by the E-UTRAN. Definition derived from TS 23.401.
Removal of eCall only mode restriction:
All the limitations as described in TS 22.101 for the eCall only mode do not apply any more.
RLOS EPS bearer context:
A default RLOS EPS bearer context which was activated with request type "RLOS", or any dedicated EPS bearer context associated to this default EPS bearer context.
The label (S1 mode only) indicates that this clause or paragraph applies only to a system which operates in S1 mode, i.e. with a functional division that is in accordance with the use of an S1 interface between the radio access network and the core network. The S1 mode includes WB-S1 mode and NB-S1 mode. In a multi-access system this case is determined by the current serving radio access network or the current serving satellite access network.
Satellite E-UTRAN RAT type:
In case of satellite E-UTRAN access, RAT types are used to distinguish different types of satellite E-UTRAN access, as defined in TS 38.413. In this version of the specification, the defined satellite E-UTRAN RAT types are "WB-E-UTRAN(LEO)", "WB-E-UTRAN(MEO)", " WB-E-UTRAN(GEO)", "NB-IoT(LEO)", "NB-IoT(MEO)", "NB-IoT(GEO)", "LTE-M(LEO)", "LTE-M(MEO)" and "LTE-M(GEO)".
SCEF PDN Connection:
A PDN connection established between the UE and the Service Capability Exposure Function (SCEF) for transmitting the UE's non-IP data related to a specific application.
SGi PDN Connection:
A PDN connection established between the UE and the Packet Gateway (P-GW) for transmitting the UE's IP, non-IP or Ethernet data related to a specific application.
S101 mode:
Applies to a system that operates with a functional division that is in accordance with the use of an S101 interface. For the definition of the S101 reference point, see TS 23.402.
SIPTO at the local network PDN connection:
A PDN connection, for which the default EPS bearer context or default PDP context was activated with an APN authorized to use SIPTO at the local network and it was activated such that the traffic of the PDN connection will be using an L-GW. The network authorizes an APN for using SIPTO at the local network based on the subscription profile (see TS 29.272) and subsequently the network considers this PDN connection a SIPTO at the local network PDN connection. SIPTO at the local network PDN connection can be of IP, non-IP or Ethernet PDN type.
SIPTO at the local network PDN connection with a collocated L-GW:
A SIPTO at the local network PDN connection which is established to a L-GW function collocated with the (H)(e)NodeB. The core-network entity (i.e. the MME or the SGSN) can be aware of whether the SIPTO at the local network PDN connection with a collocated L-GW is used when the PDN connection is established.
SIPTO at the local network PDN connection with a stand-alone GW:
A SIPTO at the local network PDN connection which is established to a stand-alone GW (with collocated L-GW and S-GW). The core-network entity (i.e. the MME or the SGSN) can be aware of whether the SIPTO at the local network PDN connection with a stand-alone GW is used when the PDN connection is established.
"SMS only":
A subset of services which includes only Short Message Service. A UE camping on E-UTRAN can attach to both EPS services and "SMS only".
SMS over NAS:
refers to SMS in MME or SMS over SGs.
SMS over S102:
refers to SMS which uses 1xCS procedures in EPS as defined in TS 23.272.
Subscribed APN based congestion control:
Congestion control in mobility management where the network can reject attach requests from UEs with a certain APN in the subscription.
TAI list:
A list of TAIs that identify the tracking areas that the UE can enter without performing a tracking area updating procedure. The TAIs in a TAI list assigned by an MME to a UE pertain to the same MME area.
Traffic flow aggregate:
A temporary aggregate of packet filters that are included in a UE requested bearer resource allocation procedure or a UE requested bearer resource modification procedure and that is inserted into a traffic flow template (TFT) for an EPS bearer context by the network once the UE requested bearer resource allocation procedure or UE requested bearer resource modification procedure is completed.
UE configured for dual priority:
A UE which provides dual priority support is configured for NAS signalling low priority and also configured to override the NAS signalling low priority indicator (see TS 24.368, TS 31.102).
UE configured to use AC11 - 15 in selected PLMN:
A UE configured with at least one access class in the range 11-15 on the USIM, and the access class is applicable in the selected PLMN according to TS 22.011.
UE's availability for voice calls in the IMS:
The indication of this availability or non-availability is provided by the upper layers of the UE as specified in TS 24.229 in the annex relevant to the IP-Connectivity Access Network in use or determined in the NAS layer, as specified in clause 4.3.1. If availability is indicated, the UE uses the IM CN Subsystem and can terminate or originate requests for SIP sessions including an audio component with codecs suited for voice.
UE's usage setting:
This is a UE setting that indicates whether the UE has preference for voice services over data services or vice-versa. If a UE has preference for voice services, then the UE's usage setting is "voice centric". If a UE has preference for data services, then the UE's usage setting is "data centric". A UE whose setting is "data centric" may still require access to voice services. A UE whose setting is "voice centric" may still require access to data services. This definition is derived from TS 23.221 and it applies to voice capable UEs. If the UE is capable of both S1 mode and N1 mode, there is a single UE's usage setting which applies to both 5GS and EPS (see TS 24.501).
UE supporting CIoT EPS optimizations:
A UE that supports control plane CIoT EPS optimization or user plane CIoT EPS optimization and one or more other CIoT EPS optimizations when the UE is in S1 mode.
UE using EPS services with control plane CIoT EPS optimization:
A UE that is attached for EPS services with the control plane CIOT EPS optimization accepted by the network.
User plane CIoT EPS optimization:
Signalling optimizations to enable efficient transport of user data (IP, non-IP or Ethernet) over the user plane.
For the purposes of the present document, the following terms and definitions given in TS 23.221 apply:
Restricted local operator services
For the purposes of the present document, the following terms and definitions given in TS 23.401 apply:
APN rate control status
Cellular IoT (CIoT)
DCN-ID
eCall only mode
NarrowBand-IoT
Dedicated core network
PDN connection
Service Gap Control
UE paging probability information
For the purposes of the present document, the following terms and definitions given in TS 23.272 apply:
CS fallback
SMS in MME
SMS over SGs
For the purposes of the present document, the following terms and definitions given in TS 23.682 apply:
SCEF
For the purposes of the present document, the following terms and definitions given in TS 24.008 apply:
A/Gb mode
Access domain selection
Default PDP context
Extended idle-mode DRX cycle
Iu mode
Native P-TMSI
Power saving mode
PS signalling connection
RR connection
TFT
For the purposes of the present document, the following terms and definitions given in TS 33.102 apply:
UMTS security context
For the purposes of the present document, the following terms and definitions given in TS 33.401 apply:
Current EPS security context
Full native EPS security context
KASME
K'ASME
Mapped security context
Native EPS security context
Non-current EPS security context
Partial native EPS security context
Data via MME
For the purposes of the present document, the following terms and definitions given in TS 23.122 apply:
Country
Discontinuous Coverage
EHPLMN
HPLMN
Shared Network
Suitable Cell
VPLMN
Limited Service State
For the purposes of the present document, the following terms and definitions given in TS 23.216 apply:
SRVCC
vSRVCC
For the purposes of the present document, the following terms and definitions given in TS 22.011 apply:
Extended Access Barring
Application specific Congestion control for Data Communication (ACDC)
For the purposes of the present document, the following terms and definitions given in TS 23.003 apply:
Local Home Network Identifier
For the purposes of the present document, the following terms and definitions given in TS 23.303 apply:
ProSe direct communication
ProSe direct discovery
ProSe UE-to-Network Relay
For the purposes of the present document, the following terms and definitions given in TS 24.161 apply:
Multi-access PDN connection
NBIFOM
For the purposes of the present document, the following terms and definitions given in TS 23.167 apply:
eCall over IMS
For the purposes of the present document, the following terms and definitions given in TS 24.501 apply:
5G-EA
5G-IA
5GMM-CONNECTED mode
5GMM-DEREGISTERED
5GMM-DEREGISTERED-INITIATED
5GMM-IDLE mode
5GMM-NULL
5GMM-REGISTERED
5GMM-REGISTERED-INITIATED
5GMM-SERVICE-REQUEST-INITIATED
Applicable UE radio capability ID for the current UE radio configuration in the selected network
Control plane CIoT 5GS optimization
N1 mode
NB-N1 mode
Native 5G-GUTI
Service-level-AA
UE operating in single-registration mode in a network supporting N26 interface
UE supporting UAS services
User plane CIoT 5GS optimization
For the purposes of the present document, the following terms and definitions given in TS 36.413 apply:
User Location Information
For the purposes of the present document, the following terms and its definitions given in TS 23.256 apply:
3GPP UAV ID
CAA (Civil Aviation Administration)-Level UAV Identity
Command and Control (C2) Communication
UAV controller (UAV-C)
UAS Services
UAS Service Supplier (USS)
Uncrewed Aerial System (UAS)
USS communication
UUAA
UUAA-SM
Direct C2 communication
3.2 Abbreviations p. 33
For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
5G-GUTI
5G-Globally Unique Temporary Identifier
5GMM
5GS Mobility Management
5GS
5G System
ACDC
Application specific Congestion control for Data Communication
AKA
Authentication and Key Agreement
AMBR
Aggregate Maximum Bit Rate
APN
Access Point Name
APN-AMBR
APN Aggregate Maximum Bit Rate
ARP
Allocation Retention Priority
ATSSS
Access Traffic Steering, Switching and Splitting
BCM
Bearer Control Mode
CIoT
Cellular IoT
CP CIoT
Control Plane CIoT
CP-EDT
Control Plane EDT
CSG
Closed Subscriber Group
E-UTRA
Evolved Universal Terrestrial Radio Access
E-UTRAN
Evolved Universal Terrestrial Radio Access Network
EAB
Extended Access Barring
ECM
EPS Connection Management
eDRX
Extended idle-mode DRX cycle
EDT
Early Data Transmission
EENLV
Extended Emergency Number List Validity
eKSI
Key Set Identifier for E-UTRAN
EMM
EPS Mobility Management
eNode B
Evolved Node B
EPC
Evolved Packet Core Network
EPS
Evolved Packet System
EPS-UPIP
User-plane integrity protection in EPS
ESM
EPS Session Management
FQDN
Fully Qualified Domain Name
GBR
Guaranteed Bit Rate
GEO
Geostationary Orbit
GUMMEI
Globally Unique MME Identifier
GUTI
Globally Unique Temporary Identifier
HeNB
Home eNode B
HRPD
High Rate Packet Data
IoT
Internet of Things
IP-CAN
IP-Connectivity Access Network
ISR
Idle mode Signalling Reduction
kbps
Kilobits per second
KSI
Key Set Identifier
L-GW
Local PDN Gateway
LEO
Low Earth Orbit
LHN-ID
Local Home Network Identifier
LIPA
Local IP Access
M-TMSI
M-Temporary Mobile Subscriber Identity
MAC
Message Authentication Code
MA PDU
Multi-Access PDU
Mbps
Megabits per second
MBR
Maximum Bit Rate
MEO
Medium Earth Orbit
MME
Mobility Management Entity
MMEC
MME Code
MT-EDT
Mobile Terminated-Early Data Transmission
MUSIM
Multi-USIM
NB-IoT
Narrowband IoT
NR
New Radio
NSSAI
Network Slice Selection Assistance Information
PD
Protocol Discriminator
PDN GW
Packet Data Network Gateway
ProSe
Proximity-based Services
PSM
Power Saving Mode
PTI
Procedure Transaction Identity
QCI
QoS Class Identifier
QoS
Quality of Service
RACS
Radio Capability Signalling Optimisation
RLOS
Restricted Local Operator Services
ROHC
RObust Header Compression
RRC
Radio Resource Control
S-NSSAI
Single NSSAI
S-TMSI
S-Temporary Mobile Subscriber Identity
S101-AP
S101 Application Protocol
S1AP
S1 Application Protocol
SAE
System Architecture Evolution
SCEF
Service Capability Exposure Function
SDNAEPC
Secondary DN authentication and authorization over EPC
SGC
Service Gap Control
SIPTO
Selected IP Traffic Offload
TA
Tracking Area
TAC
Tracking Area Code
TAI
Tracking Area Identity
TFT
Traffic Flow Template
TI
Transaction Identifier
TIN
Temporary Identity used in Next update
UAS
Uncrewed Aerial System
UAV
Uncrewed Aerial Vehicle
URN
Uniform Resource Name
URSP
UE Route Selection Policy
USS
UAS Service Supplier
UUAA
USS UAV Authorization/Authentication
V2X
Vehicle-to-Everything
WUS
Wake-Up Signal
