5G/NR - NAS |
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Registration in a Nutshell
Registration in Detail
Registration process in 5G/NR is similar to the Attach Process in LTE except many of the new Information elements added or renamed in various NAS message mainly due to core network structure changes in 5G/NR.
NOTE : 'Registration' in this note refer to specific NAS messages, not about the full attach sequence. For the details of full registration, check out this note.
According to 24.501 - 5.5.1.2, Registration sequence for initial attach goes as follows. It can go through a little bit different path depending on how NW respond to UE after it get Registration Request.
< Case A > Normal Registration
< Case B > No Registration Accept
< Case C > Registration Reject
Following is a table listing various reject cause and the expected UE behavior based on 24.501-5.5.1.2.5. I put only high level and most critical (most critical to me) in the 'Expected UE behavior' column. There are much more futher details specified in the specification.
There are several important NAS signaling messages related to 5G registration. In this section, I will summarize about a few most important messages and look into its structure.
The "Registration Request" message is used by the mobile device to initiate the registration process with the 5G core network. The Registration Request message contains important information about the mobile device, and is sent to the 5G core network via the Radio Access Network (RAN) and conveyed to AMF. The message also contains other information such as the device's capabilities and supported network features.
Followings are information that are included in RegistrationRequest message. Click on the link to get the details of each components (Information Elements). Registration Request (24.501 - 8.2.6.1) followOnRequest registration Type (24.501 - 9.11.3.7) ngKSI (24.501 - 9.11.3.32) 5GS MobileIdentity (24.501 - 9.11.3.4) non-Current Native NAS key set identifier (24.501 - 9.11.3.32) 5GMM Capability (24.501 - 9.11.3.1) ue Security Capability (24.501 - 9.11.3.54) Requested NSSAI (24.501 - 9.11.3.37) last Visited Registered TAI (24.501 - 9.11.3.8) s1 Ue Network Capability (24.501 - 9.11.3.48) uplink Data Status (24.501 - 9.11.3.57) pdu Session Status (24.501 - 9.11.3.44) MICOIndication (24.501 - 9.11.3.31) ue Status (24.501 - 9.11.3.56) additional GUTI (24.501 - 9.11.3.4) allowed Pdu Session Status (24.501 - 9.11.3.13) ue Usage Setting (24.501 - 9.11.3.55) requested Drx Parameters (24.501 - 9.11.3.2A) EPS Nas Message Container (24.501 - 9.11.3.24) LADN Indication (24.501 - 9.11.3.29) payload Container Type (24.501 - 9.11.3.40) payload Container (24.501 - 9.11.3.39) Network Slicing Indication (24.501 - 9.11.3.36) 5GS Update Type (24.501 - 9.11.3.9A) NAS Message Container (24.501 - 9.11.3.33) EPS Bearer Context Status (24.501 - 9.11.3.23A)
Example 01 > UEIC=SUCI, No Requested NASSI
This is a sample message from the log provided by Amarisoft.
Protocol discriminator = 0x7e (5GS Mobility Management)
Security header = 0x0 (Plain 5GS NAS message, not security protected)
Message type = 0x41 (Registration request)
5GS registration type:
Follow-on request bit = 1
Value = 1 (initial registration)
ngKSI:
TSC = 0
NAS key set identifier = 7
5GS mobile identity:
SUCI
SUPI format = 0 (IMSI)
MCC = 001
MNC = 01
Routing indicator = 0000
Protection sheme id = 0 (Null scheme)
Home network public key identifier = 0
MSIN = 0123456789
5GMM capability:
0x03 (LPP=0, HO attach=1, S1 mode=1)
UE security capability:
0xf0 (5G-EA0=1, 128-5G-EA1=1, 128-5G-EA2=1, 128-5G-EA3=1, 5G-EA4=0, 5G-EA5=0,
5G-EA6=0, 5G-EA7=0)
0xf0 (5G-IA0=1, 128-5G-IA1=1, 128-5G-IA2=1, 128-5G-IA3=1, 5G-IA4=0, 5G-IA5=0,
5G-IA6=0, 5G-IA7=0)
S1 UE network capability:
0xf0 (EEA0=1, 128-EEA1=1, 128-EEA2=1, 128-EEA3=1, EEA4=0, EEA5=0, EEA6=0, EEA7=0)
0xf0 (EIA0=1, 128-EIA1=1, 128-EIA2=1, 128-EIA3=1, EIA4=0, EIA5=0, EIA6=0, EIA7=0)
0xc0 (UEA0=1, UEA1=1, UEA2=0, UEA3=0, UEA4=0, UEA5=0, UEA6=0, UEA7=0)
0xc0 (UCS2=1, UIA1=1, UIA2=0, UIA3=0, UIA4=0, UIA5=0, UIA6=0, UIA7=0)
0x01 (ProSe-dd=0, ProSe=0, H.245-ASH=0, ACC-CSFB=0, LPP=0, LCS=0, 1xSRVCC=0, NF=1)
0x80 (ePCO=1, HC-CP CIoT=0, ERw/oPDN=0, S1-U data=0, UP CIoT=0, CP CIoT=0,
ProSe-relay=0, ProSe-dc=0)
0x30 (15 bearers=0, SGC=0, N1mode=1, DCNR=1, CP backoff=0, RestrictEC=0,
V2X PC5=0, multipleDRB=0)
Example 02 > UEIC=GUTI, Requested NASSI
This is a sample message from the log from Amarisoft callbox. Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x1 (Integrity protected) Auth code = 0xc2653407 Sequence number = 0x09 Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x0 (Plain 5GS NAS message, not security protected) Message type = 0x41 (Registration request) 5GS registration type: Follow-on request bit = 1 Value = 1 (initial registration) ngKSI: TSC = 0 NAS key set identifier = 2 5GS mobile identity: 5G-GUTI MCC = 001 MNC = 01 AMF Region ID = 128 AMF Set ID = 4 AMF Pointer = 1 5G-TMSI = 0x2fedc8c7 UE security capability: 0xf0 (5G-EA0=1, 128-5G-EA1=1, 128-5G-EA2=1, 128-5G-EA3=1, 5G-EA4=0, 5G-EA5=0, 5G-EA6=0, 5G-EA7=0) 0x70 (5G-IA0=0, 128-5G-IA1=1, 128-5G-IA2=1, 128-5G-IA3=1, 5G-IA4=0, 5G-IA5=0, 5G-IA6=0, 5G-IA7=0) 0xf0 (EEA0=1, 128-EEA1=1, 128-EEA2=1, 128-EEA3=1, EEA4=0, EEA5=0, EEA6=0, EEA7=0) 0x70 (EIA0=0, 128-EIA1=1, 128-EIA2=1, 128-EIA3=1, EIA4=0, EIA5=0, EIA6=0, EIA7=0) NAS message container: Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x0 (Plain 5GS NAS message, not security protected) Message type = 0x41 (Registration request) 5GS registration type: Follow-on request bit = 1 Value = 1 (initial registration) ngKSI: TSC = 0 NAS key set identifier = 2 5GS mobile identity: 5G-GUTI MCC = 001 MNC = 01 AMF Region ID = 128 AMF Set ID = 4 AMF Pointer = 1 5G-TMSI = 0x2fedc8c7 5GMM capability: 0x03 (SGC=0, 5G-IPHC-CP CIoT=0, N3 data=0, 5G-CP CIoT=0, RestrictEC=0, LPP=0, HO attach=1, S1 mode=1) UE security capability: 0xf0 (5G-EA0=1, 128-5G-EA1=1, 128-5G-EA2=1, 128-5G-EA3=1, 5G-EA4=0, 5G-EA5=0, 5G-EA6=0, 5G-EA7=0) 0x70 (5G-IA0=0, 128-5G-IA1=1, 128-5G-IA2=1, 128-5G-IA3=1, 5G-IA4=0, 5G-IA5=0, 5G-IA6=0, 5G-IA7=0) 0xf0 (EEA0=1, 128-EEA1=1, 128-EEA2=1, 128-EEA3=1, EEA4=0, EEA5=0, EEA6=0, EEA7=0) 0x70 (EIA0=0, 128-EIA1=1, 128-EIA2=1, 128-EIA3=1, EIA4=0, EIA5=0, EIA6=0, EIA7=0) Requested NSSAI: S-NSSAI Length of S-NSSAI contents = 1 (SST) SST = 0x01 Last visited registered TAI: MCC = 001 MNC = 01 TAC = 0x000064 S1 UE network capability: 0xf0 (EEA0=1, 128-EEA1=1, 128-EEA2=1, 128-EEA3=1, EEA4=0, EEA5=0, EEA6=0, EEA7=0) 0x70 (EIA0=0, 128-EIA1=1, 128-EIA2=1, 128-EIA3=1, EIA4=0, EIA5=0, EIA6=0, EIA7=0) 0xc0 (UEA0=1, UEA1=1, UEA2=0, UEA3=0, UEA4=0, UEA5=0, UEA6=0, UEA7=0) 0x40 (UCS2=0, UIA1=1, UIA2=0, UIA3=0, UIA4=0, UIA5=0, UIA6=0, UIA7=0) 0x19 (ProSe-dd=0, ProSe=0, H.245-ASH=0, ACC-CSFB=1, LPP=1, LCS=0, 1xSRVCC=0, NF=1) 0x80 (ePCO=1, HC-CP CIoT=0, ERw/oPDN=0, S1-U data=0, UP CIoT=0, CP CIoT=0, ProSe-relay=0, ProSe-dc=0) 0xb0 (15 bearers=1, SGC=0, N1mode=1, DCNR=1, CP backoff=0, RestrictEC=0, V2X PC5=0, multipleDRB=0) UE's usage setting = 0x01 (Data centric) LADN indication: Length = 0 Data = Network slicing indication = 0x00 (DCNI=0, NSSCI=0) 5GS update type = 0x01 (EPS-PNB-CIoT=no additional information, 5GS-PNB-CIoT=no additional information, NG-RAN-RCU=0, SMS requested=1)
Example 03 > UEIC=SUCI, Multiple Requested NASSI
This is a sample message from the log from Amarisoft callbox. Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x4 (Integrity protected and ciphered with new 5G NAS security context) Auth code = 0x291dbc03 Sequence number = 0x00 Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x0 (Plain 5GS NAS message, not security protected) Message type = 0x5e (Security mode complete) IMEISV: IMEISV = 0123456700000101 NAS message container: Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x0 (Plain 5GS NAS message, not security protected) Message type = 0x41 (Registration request) 5GS registration type: Follow-on request bit = 1 Value = 1 (initial registration) ngKSI: TSC = 0 NAS key set identifier = 7 5GS mobile identity: SUCI SUPI format = 0 (IMSI) MCC = 001 MNC = 01 Routing indicator = 0 Protection sheme id = 0 (Null scheme) Home network public key identifier = 0 MSIN = 0123456789 5GMM capability: 0x00 (SGC=0, 5G-IPHC-CP CIoT=0, N3 data=0, 5G-CP CIoT=0, RestrictEC=0, LPP=0, HO attach=0, S1 mode=0) UE security capability: 0xe0 (5G-EA0=1, 128-5G-EA1=1, 128-5G-EA2=1, 128-5G-EA3=0, 5G-EA4=0, 5G-EA5=0, 5G-EA6=0, 5G-EA7=0) 0xe0 (5G-IA0=1, 128-5G-IA1=1, 128-5G-IA2=1, 128-5G-IA3=0, 5G-IA4=0, 5G-IA5=0, 5G-IA6=0, 5G-IA7=0) Requested NSSAI: S-NSSAI Length of S-NSSAI contents = 4 (SST and SD) SST = 0x01 SD = 0x000001 S-NSSAI Length of S-NSSAI contents = 4 (SST and SD) SST = 0x03 SD = 0x000032 UE's usage setting = 0x01 (Data centric) Network slicing indication = 0x02 (DCNI=1, NSSCI=0) 5GS update type = 0x01 (EPS-PNB-CIoT=no additional information, 5GS-PNB-CIoT=no additional information, NG-RAN-RCU=0, SMS requested=1)
5G Core would send Registration Accept message if all the information from RegistrationRequest message is acceptable and all the authentication and security processes are completed.
Registration Accept (24.501 - 8.2.7.1) 5GS registration result (24.501 - 9.11.3.6) 5G-GUTI (24.501 - 9.11.3.4) Equivalent PLMNs (24.501 - 9.11.3.45) TAI list (24.501 - 9.11.3.9) Allowed NSSAI (24.501 - 9.11.3.37) Rejected NSSAI (24.501 - 9.11.3.46) Configured NSSAI (24.501 - 9.11.3.37) 5GS network feature support (24.501 - 9.11.3.5) PDU session status (24.501 - 9.11.3.44) PDU session reactivation result (24.501 - 9.11.3.42) PDU session reactivation result error cause (24.501 - 9.11.3.43) LADN information (24.501 - 9.11.3.30) MICO indication (24.501 - 9.11.3.31) Network Slicing Indication (24.501 - 9.11.3.36) Service Area List (24.501 - 9.11.3.49) T3512 value (24.501 - 9.11.2.5) Non-3GPP de-registration timer value (24.501 - 9.11.2.4) T3502 value (24.501 - 9.11.2.4) Emergency number list (24.501 - 9.11.3.23) Extended Emergency number list (24.501 - 9.11.3.26) SOR transparent container (24.501 - 9.11.3.51) EAP message (24.501 - 9.11.2.2) NSSAI inclusion mode (24.501 - 9.11.3.37A) Operator-defined access category definitions (24.501 - 9.11.3.38) Negotiated DRX parameters (24.501 - 9.11.3.2A) Non-3GPP NW policies (24.501 - 9.11.3.36A) EPS Bearer Context Status (24.501 - 9.11.3.23A)
Example 01 > UE ID = GUTI, Allowed NSSAI
This is a sample message from the log provided by Amarisoft.
Protocol discriminator = 0x7e (5GS Mobility Management)
Security header = 0x2 (Integrity protected and ciphered)
Auth code = 0xb5719578
Sequence number = 0x01
Protocol discriminator = 0x7e (5GS Mobility Management)
Security header = 0x0 (Plain 5GS NAS message, not security protected)
Message type = 0x42 (Registration accept)
5GS registration result = 0x09 (SMS allowed=1, 3GPP access)
5G-GUTI:
5G-GUTI
MCC = 001
MNC = 01
AMF Region ID = 128
AMF Set ID = 4
AMF Pointer = 1
5G-TMSI = 0x82fbff80
TAI list:
Length = 7
Data = 00 00 f1 10 00 00 64
Allowed NSSAI:
S-NSSAI
Length of S-NSSAI contents = 1 (SST)
SST = 0x00
5GS network feature support:
0x01 (MPSI=0, IWK N26=0, EMF=not supported, EMC=not supported,
IMS-VoPS-N3GPP=0, IMS-VoPS-3GPP=1)
0x00 (MCSI=0, EMCN3=0)
T3512 value:
Value = 30
Unit = 5 (1 minute)
Emergency number list:
Length = 8
Data = 03 1f 19 f1 03 1f 11 f2
Example 02 > UE ID = GUTI, Multiple Allowed NSSAI
This is a sample message from the log provided by Amarisoft. Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x2 (Integrity protected and ciphered) Auth code = 0x091863db Sequence number = 0x01 Protocol discriminator = 0x7e (5GS Mobility Management) Security header = 0x0 (Plain 5GS NAS message, not security protected) Message type = 0x42 (Registration accept) 5GS registration result = 0x09 (Emergency registered=0, NSSAA to be performed=0, SMS allowed=1, 3GPP access) 5G-GUTI: 5G-GUTI MCC = 001 MNC = 01 AMF Region ID = 128 AMF Set ID = 4 AMF Pointer = 1 5G-TMSI = 0xc69f2cdc TAI list: Length = 7 Data = 00 00 f1 10 00 00 64 Allowed NSSAI: S-NSSAI Length of S-NSSAI contents = 4 (SST and SD) SST = 0x01 SD = 0x000001 S-NSSAI Length of S-NSSAI contents = 4 (SST and SD) SST = 0x03 SD = 0x000032 5GS network feature support: 0x03 (MPSI=0, IWK N26=0, EMF=not supported, EMC=not supported, IMS-VoPS-N3GPP=1, IMS-VoPS-3GPP=1) 0x00 (5G-UP CIoT=0, 5G-IPHC-CP CIoT=0, N3 data=0, 5G-CP CIoT=0, RestrictEC=both CE mode A and CE mode B are not restricted, MCSI=0, EMCN3=0) T3512 value: Value = 30 Unit = 5 (1 minute) Emergency number list: Length = 8 Data = 03 1f 19 f1 03 1f 11 f2
Registration complete (24.501 - 8.2.8.1) 5GS registration result (24.501 - 9.11.3.51)
This is a sample message from the log provided by Amarisoft.
Protocol discriminator = 0x7e (5GS Mobility Management)
Security header = 0x2 (Integrity protected and ciphered)
Auth code = 0x6f97640e
Sequence number = 0x01
Protocol discriminator = 0x7e (5GS Mobility Management)
Security header = 0x0 (Plain 5GS NAS message, not security protected)
Message type = 0x43 (Registration complete)
In this section, I want to highlight and summarize some of the important Information Elements used in Registration related NAS message.
The 5GS registration type parameter in the Registration Request message enables the 5G core network to identify the type of registration that the mobile device is requesting, and to initiate the appropriate registration procedure. 5GS registration type value (3bits) 1=initial registration 2=mobility registration updating 3=periodic registration updating 4=emergency registration 6=reserved
Follow-on request (1 bit) 0=No follow-on request pending // the AMF initiates the release of the UE context // after registration complete message 1=Follow-on request pending The Follow-on request is used to indicate that the mobile device is requesting a follow-on procedure, which is a specific type of mobility registration.
The Follow-on procedure is used when the mobile device has moved to a new location within the same 5G core network, but has not lost the radio connection with the previous location. This can occur when the mobile device moves from one cell to another within the same location area or tracking area, or when the mobile device is handed over between different radio access technologies (RATs) that are served by the same core network.
When the mobile device requests a Follow-on procedure using the "Follow-on request" parameter, the 5G core network can use the previous registration context to quickly re-establish the connection with the mobile device in the new location, without requiring a full authentication and authorization process. This helps to reduce the delay and signaling overhead involved in the registration process, and enables the mobile device to maintain continuity of service during the mobility transition.
5G Registration Request message is used by a device to identify itself to the 5G network when initiating registration. It contains the mobile device's International Mobile Subscriber Identity (IMSI) or other unique identifier, such as a Temporary Mobile Subscriber Identity (TMSI) or a 5G Globally Unique Temporary Identity (5G-GUTI). No identity SUCI SUCI (SUPI Format = IMSI) mcc mnc Routing Indicator (16 bit, 4 digit) Protection scheme Id (4 bit) Home network public key identifier (8 bit) Scheme output (n Bytes) SUCI (SUPI Format = Network specific identifier) Type of identity (3 bit) SUCI NAI (n bytes) 5G-GUTI mcc mnc AMF Region ID (8 bit) AMF Set ID (10 bit) AMF Pointer (6 bit) 5G TMSI (32 bit) IMEI 5G-S-TMSI AMF Set ID (8 bit) AMF Pointer (8 bit) 5G - TMSI(32 bit) IMEISV
EPC NAS supported (S1 mode) S1 mode not supported S1 mode supported ATTACH REQUEST message containing PDN CONNECTIVITY REQUEST message for handover support (HO attach) ATTACH REQUEST message containing PDN CONNECTIVITY REQUEST message with request type set to "handover" or "handover of emergency bearer services" to transfer PDU session from N1 mode to S1 mode not supported ATTACH REQUEST message containing PDN CONNECTIVITY REQUEST message with request type set to "handover" or "handover of emergency bearer services" to transfer PDU session from N1 mode to S1 mode supported LTE Positioning Protocol (LPP) capability LPP in N1 mode not supported LPP in N1 mode supported
This field is present in the NAS (Non-Access Stratum) message of the 5G Attach Accept message and it indicates the status of the attach procedure for the UE.
< 24.501 - Figure 9.11.3.6.1: 5GS registration result information element > 5GS registration result value (3bit) 3GPP access Non-3GPP access 3GPP access and non-3GPP access reserved SMS over NAS transport allowed (SMS allowed) (1bit) SMS over NAS not allowed SMS over NAS allowed NSSAA to be performed : Network slice-specific authentication and authorization is to be performed Network slice-specific authentication and authorization is not to be performed Network slice-specific authentication and authorization is to be performed Emergency registered Not registered for emergency services Registered for emergency services
IMS voice over PS session over 3GPP access indicator (IMS-VoPS-3GPP) IMS voice over PS session not supported over 3GPP access IMS voice over PS session supported over 3GPP access IMS voice over PS session over non-3GPP access indicator (IMS-VoPS-N3GPP) IMS voice over PS session not supported over non-3GPP access IMS voice over PS session supported over non-3GPP access Emergency service support indicator for 3GPP access (EMC) Emergency services not supported Emergency services supported in NR connected to 5GCN only Emergency services supported in E-UTRA connected to 5GCN only Emergency services supported in NR connected to 5GCN and E-UTRA Emergency service fallback indicator for 3GPP access (EMF) Emergency services fallback not supported Emergency services fallback supported in NR connected to 5GCN only Emergency services fallback supported in E-UTRA connected to 5GCN only Emergency services fallback supported in NR connected to 5GCN and E-UTRA connected to 5GCN Interworking without N26 interface indicator (IWK N26) Interworking without N26 interface not supported Interworking without N26 interface supported MPS indicator (MPSI) Access identity 1 not valid in RPLMN or equivalent PLMN Access identity 1 valid in RPLMN or equivalent PLMN Emergency service support for non-3GPP access indicator (EMCN3) Emergency services not supported over non-3GPP access Emergency services supported over non-3GPP access MCS indicator (MCSI) Access identity 2 not valid in RPLMN or equivalent PLMN Access identity 2 valid in RPLMN or equivalent PLMN
SMS over NAS transport requested (SMS requested) 0 SMS over NAS not supported 1 SMS over NAS supported NG-RAN Radio Capability Update (NG-RAN-RCU) 0 NG-RAN radio capability update not needed 1 NG-RAN radio capability update needed
The Allowed NSSAI indicates the network slice(s) that the mobile device is allowed to use based on the network's policy and available resources. To understand the role of this IE in the context of real 5G operation, you need to have a good understandings on Network Slicing. I would recommend you to check out the note on Network Slicing for further details.
< 24.501 - Figure 9.11.3.37.1: NSSAI information element >
< 24.501 - Figure 9.11.2.8.1: S-NSSAI information element >
All 0 : indicates that the user-plane resources of corresponding PDU session is not allowed to be re-established over 3GPP access. All 1 : indicates that the user-plane resources of corresponding PDU session can be re-established over 3GPP access.
24.501-8.2.7.7 states : The network may include this IE if the network needs to provide the UE with a new configured NSSAI for the current PLMN or SNPN.
To understand the role of this IE in the context of real 5G operation, you need to have a good understandings on Network Slicing. I would recommend you to check out the note on Network Slicing for further details.
< 24.501 - Figure 9.11.3.37.1: NSSAI information element >
< 24.501 - Figure 9.11.2.8.1: S-NSSAI information element >
LADN(Local Area Data Network) Indication
LADN DNN value 1 LADN DNN value 2 ... LADN DNN value n
LADN 1 DNN Value (24.501 - 9.11.2.1A) 5GS tracking area identity list LADN 2 DNN Value 5GS tracking area identity list .... LADN n DNN Value 5GS tracking area identity list
MICO(Mobile Initiated Connection Only) indication
0 : all PLMN registration area not allocated 1 : all PLMN registration area allocated
24.501-9.11.3.36 states as follows : The purpose of the Network slicing indication information element is to indicate additional information associated with network slicing in the generic UE configuration update procedure and the registration procedure, other than the user's configured NSSAI, allowed NSSAI, pending NSSAI and rejected NSSAI information.
< 24.501-Figure 9.11.3.36.1: Network slicing indication >
Network slicing subscription change indication (NSSCI) - octat 1, bit 1 0 Network slicing subscription not changed 1 Network slicing subscription changed Default configured NSSAI indication (DCNI) - octat 1, bit 2 0 Requested NSSAI not created from default configured NSSAI 1 Requested NSSAI created from default configured NSSAI
In the UE to network direction bit 1 is spare. The UE shall set this bit to zero. In the network to UE direction bit 2 is spare. The network shall set this bit to zero. Bits 3 and 4 are spare and shall be coded as zero. NOTE : NSSAI stands for Network Slice Selection Assistance Information)
NSSAI (Network Slice Selection Assistance Information)
24.501-9.11.3.37 states as follows : The purpose of the NSSAI information element is to identify a collection of S-NSSAIs
< 24.501 - Figure 9.11.3.37.1: NSSAI information element >
The NSSAI is a type 4 information element with a minimum length of 4 octets and a maximum length of 146 octets.
S-NSSAI value 1 SST (Slice/Service Type) SD (Slide Differentiator) Mapped HPLMN SST Mapped HPLMN SD S-NSSAI value 2 SST (Slice/Service Type) SD (Slide Differentiator) Mapped HPLMN SST Mapped HPLMN SD .... S-NSSAI value N SST (Slice/Service Type) SD (Slide Differentiator) Mapped HPLMN SST Mapped HPLMN SD
NOTE 1: The total number of S-NSSAI values in a requested NSSAI cannot exceed eight. NOTE 2: The number of S-NSSAI values in an allowed NSSAI cannot exceed eight. NOTE 3: The number of S-NSSAI values in a configured NSSAI or pending NSSAI cannot exceed sixteen. NOTE 4: More than one S-NSSAIs in an NSSAI can have the same SST values, and optionally same SD values, which are are associated with different mapped HPLMN SST values and optionally mapped HPLMN SD values.
NSSAI(Network Slice Selection Assistance Information) inclusion mode
24.501-9.11.3.37A States as follows : The purpose of the NSSAI inclusion mode information element is to indicate the NSSAI inclusion mode in which the UE shall operate.
< 24.501 - Figure 9.11.3.37A.1: NSSAI inclusion mode information element >
[bit(2),bit(1)] = [0,0] : NSSAI inclusion mode A [bit(2),bit(1)] = [0,1] : NSSAI inclusion mode B [bit(2),bit(1)] = [1,0] : NSSAI inclusion mode C [bit(2),bit(1)] = [1,1] : NSSAI inclusion mode D
Operator-defined access category definitions Operator-defined access category definition 1 Precedence value Operator-defined access category number PSAC Standardized access category field is not included Standardized access category field is included Length of criteria Criteria DNN type OS id + OS App Id type S-NSSAI type Standardized access category Operator-defined access category definition 2 Precedence value Operator-defined access category number PSAC Standardized access category field is not included Standardized access category field is included Length of criteria Criteria DNN type OS id + OS App Id type S-NSSAI type Standardized access category .... Operator-defined access category definition n Precedence value Operator-defined access category number PSAC Standardized access category field is not included Standardized access category field is included Length of criteria Criteria DNN type OS id + OS App Id type S-NSSAI type Standardized access category
The purpose of the PDU session status information element is to indicate the state of each PDU session that can be identified by a PDU session identity(PSI).
This IE carriies a bitmap of 16 bits as labeled below. PSI(7),PSI(6),PSI(5),PSI(4),PSI(3),PSI(2),PSI(1),PSI(0) PSI(15),PSI(14),PSI(13),PSI(12),PSI(11),PSI(10),PSI(9),PSI(8) 0 or 1 for each bit indicates followings. 0 : indicates that the 5GSM state of the corresponding PDU session is PDU SESSION INACTIVE. 1 : indicates that the 5GSM state of the corresponding PDU session is not PDU SESSION INACTIVE NOTE : PSI stands for PDU Session Identity
PDU session reactivation result
This IE carriies a bitmap of 16 bits as labeled below. PSI(7),PSI(6),PSI(5),PSI(4),PSI(3),PSI(2),PSI(1),PSI(0) PSI(15),PSI(14),PSI(13),PSI(12),PSI(11),PSI(10),PSI(9),PSI(8) 0 or 1 for each bit indicates followings. 0 : indicates establishment of user-plane resources of the PDU session was not requested in the Uplink data status IE or establishment of user-plane resources of the PDU session was not allowed in the Allowed PDU session status IE or establishment of user-plane resource of the PDU session is successful. 1 : indicates either establishment of user-plane resources of the PDU session was requested in the Uplink data status IE but establishment of user-plane resource of the PDU session is not successful or indicates establishment of user-plane resources of the PDU session was allowed in the Allowed PDU session status IE butestablishment of user-plane resource of the PDU session is either not performed or not successful. NOTE : PSI stands for PDU Session Identity
PDU session reactivation result error cause PDU session ID 1 cause value 1 (8 bit) PDU session ID 2 cause value 2 ... PDU session ID N cause value N
The Requested NSSAI is used to inform the 5G core network about the network slice(s) that the mobile device is requesting to use. To understand the role of this IE in the context of real 5G operation, you need to have a good understandings on Network Slicing. I would recommend you to check out the note on Network Slicing for further details.
< 24.501 - Figure 9.11.3.37.1: NSSAI information element >
< 24.501 - Figure 9.11.2.8.1: S-NSSAI information element >
Service type value (4 bit) signalling data mobile terminated services emergency services emergency services fallback high priority access elevated signalling unused; shall be interpreted as "signalling", if received by the network unused; shall be interpreted as "signalling", if received by the network unused; shall be interpreted as "data", if received by the network unused; shall be interpreted as "data", if received by the network unused; shall be interpreted as "data", if received by the network
EMM registration status (S1 mode reg) 0 UE is not in EMM-REGISTERED state 1 UE is in EMM-REGISTERED state 5GMM registration status (N1 mode reg) 0 UE is not in 5GMM-REGISTERED state 1 UE is in 5GMM-REGISTERED state
This IE carriies a bitmap of 16 bits as labeled below. PSI(7),PSI(6),PSI(5),PSI(4),PSI(3),PSI(2),PSI(1),PSI(0) PSI(15),PSI(14),PSI(13),PSI(12),PSI(11),PSI(10),PSI(9),PSI(8) 0 or 1 for each bit indicates followings. 0 : indicates that no uplink data are pending for the corresponding PDU session identity. 1 : indicates that uplink data are pending for the corresponding PDU session identity.
Reference
[1] 5G Standalone Access Registration Signaling Messages [2] 5G Standalone Access: Registration Procedure
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