This section describes the architecture for Gx (PCRF) with respect to 5G NSA Architecture.

S6a (HSS)

S6a interface introduced new AVP "Extended-Max-Requested-BW-UL" and "Extended-Max-Requested-BW-DL" in grouped AVP "AMBR" to handle 5G throughput ranges. When the maximum bandwidth value to be set for UL (or DL, respectively) traffic is higher than 4294967295 bits per second, the "Max-Requested-Bandwidth-UL" (or DL, respectively) AVP must be present and set to the upper limit 4294967295, and the "Extended-Max-Requested-BW-UL" (or -DL, respectively) must be present, and set to the requested bandwidth value in kilobits per second.

S1AP (eNodeB)

S1AP interface introduced new AVP “Extended UE Aggregate Maximum Bit Rate Downlink” and “Extended UE Aggregate Maximum Bit Rate Uplink” in the grouped IE “UE Aggregate Maximum Bit Rate”, whose units are bits/second. If the Extended UE Aggregate Maximum Bit Rate Downlink/Uplink IE is included, the UE Aggregate Maximum Bit Rate Downlink/Uplink IE must be ignored.

Extended E-RAB MBR/GBR

S1AP interface also introduced new AVPs “Extended E-RAB Maximum Bit Rate Downlink/Uplink”, “Extended E-RAB Guaranteed Bit Rate Downlink/Uplink” in the grouped IE “GBR QoS Information”, whose units are bits/second.

NAS (UE)

Extended APN Aggregate Maximum bit rate:

As the existing IE in NAS “APN-AMBR” supports APN-AMBR values up to 65.2Gbps, to convey the 5G throughput (beyond 65.2Gbps) over NAS, a new IE “Extended APN aggregate maximum bit rate” has been introduced in all applicable NAS messages. Following is the structure of IE “Extended APN aggregate maximum bit rate” and the units for encoding/decoding.

Example:

MME to convey downlink APN-AMBR of 128Gbps in NAS, “Extended APN aggregate maximum bit rate” IE should be sent by MME as below:

Extended EPS Quality of Service

As the existing IE in NAS “EPS Quality of Service” supports MBR and GBR values up to 10Gbps, to convey the 5G throughput (beyond 10Gbps) over NAS, a new IE “Extended EPS Quality of Service” has been introduced in all applicable NAS messages. The structure of IE “Extended EPS Quality of Service” and the units for encoding/decoding is displayed below.

Unit for maximum bit rate (Octet 3)

Example:

MME to convey downlink MBR of 20 GBPS in NAS, legacy “EPS quality of service” IE should be sent by MME as below:

Extended Quality of Service IE should be sent by MME as below:

This section describes the following call flows related to the DCNR feature.

Initial Registration by DCNR capable UE

Figure 1. Call flow for Initial Registration of DCNR capable UE

1. DCNR capable UE sets “DCNR bit” in NAS message “Attach Request” in “UE Network Capability” IE.

2. MME successfully authenticates the UE

3. As part of authorization process, while sending ULR to HSS, MME advertises the DCNR support by sending “NR as Secondary RAT” feature bit in “Feature-List-ID-2”.

4. HSS sends ULA by advertising the DCNR by sending “NR as Secondary RAT” feature bit in “Feature-List-ID-2” and sends "Max-Requested-Bandwidth-UL" as 4294967295 bps, "Max-Requested-Bandwidth-DL" as 4294967295 bps and the extended bandwidth values in new "AVPs Extended-Max-Requested-BW-UL" and "Extended-Max-Requested-BW-D"L.

   If HSS determines that the UE is not authorized for DCNR services, HSS sends Subscription-Data with “Access-Restriction” carrying “NR as Secondary RAT Not Allowed”.

5. MME sends Create Session Request with the extended APN-AMBR values in existing AMBR IE. As the APN-AMBR values in GTP-v2 interface are encoded in kbps, existing AMBR IE handles the 5G-NSA bit rates.

6. P-GW sends CCR-I to PCRF advertising the DCNR by sending “Extended-BW-NR” feature bit in “Feature-List-ID-2”. P-GW also sends "APN-Aggregate-Max-Bitrate-UL" as 4294967295 Bits/Sec, "APN-Aggregate-Max-Bitrate-DL" as 4294967295 Bits/Sec and the extended bandwidth values in new AVPs "Extended-APN-AMBR-UL" and "Extended-APN-AMBR-DL".

7. PCRF sends CCA-I advertising the DCNR by sending “Extended-BW-NR” feature bit in “Feature-List-ID-2”. PCRF also sends "APN-Aggregate-Max-Bitrate-UL" as 4294967295 bps and "APN-Aggregate-Max-Bitrate-DL" as 4294967295 bps and the extended bandwidth values in new "AVPs Extended-APN-AMBR-UL" and "Extended-APN-AMBR-DL". PCRF may offer the same extended "APN-AMBR" values requested by PCEF or may modify the extended "APN-AMBR" values. P-GW enforces the "APN-AMBR" values accordingly.

8. P-GW honors the "APN-AMBR" values as offered by PCRF and sends the extended "APN-AMBR" values in existing IE "APN-AMBR" in the Create Session Response.

9. MME computes the UE-AMBR values and sends the extended UE-AMBR values in new IEs “Extended UE Aggregate Maximum Bit Rate Downlink” and “Extended UE Aggregate Maximum Bit Rate Uplink” also by setting the legacy “UE AMBR Uplink” and “UE AMBR Downlink” values to the maximum allowed value 10000000000 bps(10 Gbps) in “Initial Context Setup Request”.

   MME sends the "APN-AMBR" values up to 65.2 Gbps in existing IE "APN-AMBR" in NAS Activate Default EPS Bearer Context Request – Attach Accept. If the "APN-AMBR" values are beyond 65.2 Gbps, MME sends the extended "APN-AMBR" values in new IE “Extended APN aggregate maximum bit rate”

   If ULA is received with “Access-Restriction” carrying “NR as Secondary RAT Not Allowed”, MME sends the “Initial Context Setup Request” with “NR Restriction” bit set in “Handover Restriction List” IE. MME sets the RestrictDCNR bit to "Use of dual connectivity with NR is restricted" in the EPS network feature support IE of the ATTACH ACCEPT message. Accordingly, UE provides the indication that dual connectivity with NR is restricted to the upper layers.

   If DCNR feature is not configured at MME Service or Call Control Profile level, MME sets the RestrictDCNR bit to "Use of dual connectivity with NR is restricted" in the EPS network feature support IE of the ATTACH ACCEPT message. Accordingly, UE provides the indication that dual connectivity with NR is restricted to the upper layers.

10. eNodeB sends Initial Context Setup Response. If master eNodeB determines to establish the bearer on secondary eNodeB, F-TEID of secondary eNodeB may be sent in this step (Transport layer address and TEID of secondary eNodeB). It is transparent to MME if the bearer is established on master eNodeB or secondary eNodeB.

11. eNodeB sends Uplink NAS Transport with NAS message Attach Complete - Activate Default EPS Bearer Context Accept.

12. MME sends Modify Bearer Request to S-GW with S1-U FTEID details as received in Initial Context Setup Response.

13. MME receives Modify Bearer Response from S-GW.

E-RAB Modification Procedure

When Secondary Cell Group (SCG) bearer option is applied to support dual connectivity operation, this procedure is used to transfer bearer contexts to and from Secondary eNodeB or Secondary gNodeB.

1. The Master eNodeB sends a E-RAB Modification Indication message (eNodeB address(es) and TEIDs for downlink user plane for all the EPS bearers) to the MME. The Master eNB indicates for each bearer whether it is modified or not. “E-RAB to be Modified List” IE contains both “E-RAB to Be Modified Item IEs” and “E-RAB not to Be Modified Item IEs”. For the bearer that need to be switched to Secondary eNodeB/gNodeB, “E-RAB to Be Modified Item IEs” contains the Transport layer address of gNodeB and TEID of gNodeB.

2. The MME sends a Modify Bearer Request (eNodeB address(es) and TEIDs for downlink user plane for all the EPS bearers) message per PDN connection to the Serving GW, only for the affected PDN connections.

3. The S-GW returns a Modify Bearer Response (S-GW address and TEID for uplink traffic) message to the MME as a response to a Modify Bearer Request message.

4. For the bearers transferred to SeNB, S-GW sends one or more "end marker" packets on the old path (to Master eNodeB) immediately after switching the path.

5. The MME confirms the E-RAB modification with the E-RAB Modification Confirm message. The MME indicates for each bearer whether it was successfully modified, retained unmodified or already released by the EPC.

The 5G Non Standalone feature complies with the following standards:

• 3GPP 23.003 Release 15.2.0 - Numbering, addressing and identification.

• 3GPP 23.401 Release 15.2.0 - General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access.

• 3GPP 29.272 Release 15.2.0 - Evolved Packet System (EPS); Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN) related interfaces based on Diameter protocol.

• 3GPP 29.274 Release 15.2.0 - 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C); Stage 3.

• 3GPP 29.303 Release 15.2.0 - Domain Name System Procedures.

Use the following configuration to enable this DCNR.

configure 
   context context_name 
      mme service  service_name 
         [ no ]dcnr
           end

NOTES:

• mme-service service_name: Configures MME Service. mme_service must be an integer from 1 to 63.

• dcnr: Configures dual connectivity support with New Radio (5G).

• no: Disables the DCNR.

Use the following configuration to create and enable DCNR.

configure 
   call-control-profile call_control_profile 
      [ remove | no ] dcnr 
         end

Notes:

• call-control-profile call_control_profile: Configures Call Control Profile. call_control_profile must be an integer from 1 to 64.

• dcnr: Configures dual connectivity support with New Radio (5G).

• remove: Removes the configured values of DCNR.

• no: Disables the DCNR.

Use the following configuration to locally configure the UE-AMBR values.

configure 
   call-control-profile call_control_profile 
      qos ue-ambr max-ul max_ul_value max-dl max_dl_value
       remove qos ue-ambr  
       end

NOTES:

• call-control-profile call_control_profile: Configures Call Control Profile. call_control_profile must be an integer from 1 to 64.

• qos: (MME / S4-SGSN) Quality of Service.

• ue-ambr : UE aggregate maximum bitrate.

• max-ul : Maximum aggregate bitrate uplink.

• max-dl : Maximum aggregate bitrate downlink.

• max_ul_value: Integer value between 1 through 4000000000000(4 Tbps).

• max_dl_value: Integer value between 1 through 4000000000000(4 Tbps).

• remove: Removes the configured values of QOS UE AMBR.

Use the following configuration to locally configure the APN-AMBR values.

configure 
   apn-profile apn_profile 
      qos apn-ambr max-ul max_ul_value max-dl max_dl_value 
       remove qos apn-ambr  
         end

NOTES:

• apn-profile apn_profile: Configures APN Profile. apn_profile must be an integer from 1 to 64.

• qosl: Quality of Service.

• apn-ambr : (MME) Configures the APN AMBR.

• max-ul : maximum bitrate uplink.

• max-dl : maximum bitrate downlink.

• max_ul_value: Integer value between 1 through 4000000000000(4 Tbps).

• max_dl_value: Integer value between 1 through 4000000000000(4 Tbps).

• remove: Removes the configured values of QOS APN AMBR.

Use the following configuration to locally configure the Dedicated Bearer MBR values.

configure 
   apn-profile apn_profile 
      qos dedicated-bearer mbr max-ul max_ul_value max-dl max_dl_value 
       remove qos dedicated-bearer 
         end

NOTES:

• apn-profile apn_profile: Configures APN Profile. apn_profile must be an string from 1 to 64.

• qosl: Quality of Service.

• decicated-bearer mbr : (MME) Configures the QOS parameters for the dedicated bearer.

• max-ul : maximum bitrate uplink.

• max-dl : maximum bitrate downlink.

• max_ul_value: Integer value between 1 through 4000000000000(4 Tbps).

• max_dl_value: Integer value between 1 through 4000000000000(4 Tbps).

• remove: Removes the configured values of QOS APN AMBR.

show mme-service name [all] [name]

• DCNR - Dual Connectivity with New Radio

show mme-service statistics

• Dual Connectivity with NR Statistics:

  Attach Procedure

  • Attach Request Rcvd - Number of Attach Requests received with UE advertising DCNR support.

  • Attach Acc DCNR allowed - Number of Attach Accepts sent by the MME acknowledging the DCNR support for the UE (Restrict DCNR bit not set in Attach Accept).

  • Attach Acc DCNR denied - Number of Attach Accepts sent by the MME rejecting the DCNR support for the UE (Restrict DCNR bit set in Attach Accept).

  • Attach Reject Sent - Number of Attach Rejects sent by MME whose corresponding Attach Requests have DCNR support capability.

  • Attach Complete Rcvd - Received by MME whose corresponding Attach Requests have DCNR support capability.

  Intra MME TAU Procedure

  • TAU Request Rcvd - Number of TAU Requests received for Intra-MME TAU procedure with UE advertising DCNR support.

  • TAU Accept DCNR allowed - Number of TAU Accepts sent by the MME acknowledging the DCNR support for the UE (Restrict DCNR bit not set in TAU Accept) for Intra-MME TAU procedure.

  • TAU Accept DCNR denied - Number of TAU Accepts sent by the MME rejecting the DCNR support for the UE (Restrict DCNR bit set in TAU Accept) for Intra-MME TAU procedure.

  • TAU Complete Rcvd - Number of TAU Completes received by MME whose corresponding Intra-MME TAU Requests have DCNR support capability.

  Inter MME TAU Procedure

  • TAU Request Rcvd - Number of TAU Requests received for Inter-MME TAU procedure with UE advertising DCNR support.

  • TAU Accept DCNR allowed - Number of TAU Accepts sent by the MME acknowledging the DCNR support for the UE (Restrict DCNR bit not set in TAU Accept) for Inter-MME TAU procedure.

  • TAU Accept DCNR denied - Number of TAU Accepts sent by the MME rejecting the DCNR support for the UE (Restrict DCNR bit set in TAU Accept) for Inter-MME TAU procedure.

  • TAU Reject Sent - Number of TAU Rejects sent by the MME whose corresponding Inter-MME TAU Requests have DCNR support capability.

  • TAU Complete Rcvd - Number of TAU Completes received by MME whose corresponding Inter-MME TAU Requests have DCNR support capability.

  Dual Connectivity with NR Subscribers

  • Attached Calls - Number of DCNR supported UEs attached with the MME.

  • Connected Calls - Number of DCNR supported UEs in connected mode at MME.

  • Idle Calls - Number of DCNR supported UEs in idle mode at MME.

  Handover Statistics:

  • Intra MME Handover:

    • Path Update procedures

      • Attempted - Number of E-RAB modification indication procedures attempted (procedure level stats).

      • Success - Number of E-RAB modification indication procedures succeeded (procedure level stats).

      • Failures - Number of E-RAB modification indications procedure failed (procedure level stats).

    Bearer Statistics

    • ERAB Modification Indication

      • Attempted - Number of bearers for which E-RAB modification indications procedure Attempted (bearer level stats).

      • Success - Number of bearers for which E-RAB modification indications procedure Succeeded (bearer level stats).

      • Failures - Number of bearers for which E-RAB modification indications procedure Failed (bearer level stats).

  Node Selection:

  SGW DNS:

  • Common - Indicates the number of times SGW DNS selection procedures are performed with DNS RR excluding NR network capability. This counter increments only when the DNS RR with +nc-nr is absent.

  • NR Capable - Indicates the number of times SGW DNS selection procedures were performed with DNS RR including NR network capability. This counter increments only when the DNS RR with +nc-nr is present.

  SGW Local Config

  • Common - Indicates the number of times SGW selection procedures were performed with locally configured SGW address, without considering the NR network capability.

  PGW DNS:

  • Common - Indicates the number of times PGW DNS selection procedures were performed with DNS RR excluding NR network capability. This counter increments only when the DNS RR with +nc-nr is absent.

  • NR Capable - Indicates the number of times PGW DNS selection procedures were performed with DNS RR including NR network capability. This counter increments only when the DNS RR with +nc-nr is present.

  PGW Local Config:

  • Common - Indicates the number of times PGW selection procedures were performed with locally configured PGW address, without considering the NR network capability.

Note

When UE is defined with “UE usage type” and “NR Capable”, selection of S-GW/P-GW via DNS follows below order: MME prefers to choose S/PGW that support both services +ue and +nr If step:1 fails, MME selects S/PGW that support service +nr only If step:2 fails, MME selects S/PGW that support service +ue only If step:3 fails, MME selects S/PGW without +nr or +ue service.

show subscribers mme-service

• DCNR Devices - Dual-connectivity with New Radio.

show mme-service db record imsi

ARD:

• Dual-connectivity-NR-not-allowed - Flag to identify if ARD is received from HSS indicating DCNR feature is allowed for the given IMSI or not.

show mme-service statists s1ap

S1AP Statistics:

Transmitted S1AP Data:

• E-RAB Modification Cfm - Counter to identify the number of E-RAB Modification Confirm messages sent by MME upon successful E-RAB modification procedure.

Received S1AP Data

• E-RAB Mod Ind - Counter to identify the number of E-RAB Modification Indication messages received from Master eNodeB

show mme-service session full all

UE DC-NR Information:

• DC-NR capable UE - Counter to identify if the UE is DCNR capable

• DC-NR operation allowed - Counter to identify if the DCNR operation is allowed by MME for the DCNR capable UE

The following 5G Non Standalone feature related bulk statistics are available in the MME schema.