Netmanias Technical Document: EMM Procedure 4. Service Request 가
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EMM Procedure 4. Service Request
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Netmanias LTE Technical Documents
Visit http://www.netmanias.com to view and download m...
EMM Procedure 4. Service Request
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Abbreviations
AKA Authentication and Key Agreement
AMBR Aggregated Maximum Bit Rate
APN...
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I. Introduction
This document describes the service request procedure defined as EMM Ca...
EMM Procedure 4. Service Request
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bearer and S5 bearer) and the signaling connection (i.e. ECM connection, S11 GTP-C and ...
EMM Procedure 4. Service Request
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Figure 2. Procedures for UE-triggered Service Request (1)
❶ ECM Connection Establishmen...
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Message sent to the MME. Upon receiving the Initial UE Message, the MME allocates MME S...
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❸ E-RAB Establishment
After receiving the Service Request message from the UE, the MME ...
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completing establishment of a downlink EPS bearer (all the bearers in the downlink) fro...
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❶ Service Request Triggering
If the S-GW receives downlink data packets from the P-GW t...
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Figure 5. Procedures for Network-triggered Service Request (2)
❺ E-RAB Establishment
A...
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V. EPS Entity Information: Before/After Service Request
This chapter looks into how in...
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5.2 After Service Request
Once a service request is completed, a UE transits to ECM/RR...
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VI. Closing
In this document, we have learned the service request procedure (“EMM Case...
EMM Procedure 4. Service Request
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EMM Procedure 4. Service Request

  1. 1. Netmanias Technical Document: EMM Procedure 4. Service Request 가 www.nmcgroups.com About NMC Consulting Group NMC Consulting Group is an advanced and professional network consulting company, specializing in IP network areas (e.g., FTTH, Metro Ethernet and IP/MPLS), service areas (e.g., IPTV, IMS and CDN), and wireless network areas (e.g., Mobile WiMAX, LTE and Wi-Fi) since 2002. Copyright © 2002-2014 NMC Consulting Group. All rights reserved. EMM Procedure 4. Service Request Table of Contents I. Introduction II. Cases of Service Request III. UE-triggered Service Request IV. Network-triggered Service Request V. EPS Entity Information: Before/After Service Request VI. Closing This document, as the fourth of the EMM Procedure series, will describe the service request procedure as defined as EMM Case 4 in our technical document, “Eleven EMM Cases in an EMM Scenario”. This procedure is used when a UE, initially attached to the network but staying inactive in Idle state, wishes to use LTE services again when there is new traffic. We will discuss how E-UTRAN resources are allocated to the UE again through this procedure, establishing an ECM connection (RRC + S1 signaling connections) in the control plane, and an E-RAB (DRB + S1 bearer) in the user plane. We will also look into how information elements in EPS entities are different before and after the procedure. February 9, 2014 (Initial Released: May 10, 2012) www.netmanias.com NMC Consulting Group (tech@netmanias.com)
  2. 2. EMM Procedure 4. Service Request 1 Netmanias LTE Technical Documents Visit http://www.netmanias.com to view and download more technical documents. Index Topic Document Title Document presented here 1 Network Architecture LTE Network Architecture: Basic 2 Identification LTE Identification I: UE and ME Identifiers 3 LTE Identification II: NE and Location Identifiers 4 LTE Identification III: EPS Session/Bearer Identifiers 5 Security LTE Security I: LTE Security Concept and LTE Authentication 6 LTE Security II: NAS and AS Security 7 QoS LTE QoS: SDF and EPS Bearer QoS 8 EMM LTE EMM and ECM States 9 Eleven EMM Cases in an EMM Scenario 10 LTE EMM Procedure 1. Initial Attach - Part 1. Cases of Initial Attach 11 LTE EMM Procedure 1. Initial Attach - Part 2. Call Flow of Initial Attach 12 LTE EMM Procedure 2. Detach 13 LTE EMM Procedure 3. S1 Release 14 LTE EMM Procedure 4. Service Request O 15 LTE EMM Procedure 5. Periodic TAU 16 LTE EMM Procedure 6. Handover without TAU - Part 1. Overview of LTE Handover 17 LTE EMM Procedure 6. Handover without TAU - Part 2. X2 Handover 18 LTE EMM Procedure 6. Handover without TAU - Part 3. S1 Handover 19 LTE EMM Procedure 7. Cell Reselection without TAU 20 LTE EMM Procedure 8 & 9. Handover and Cell Reselection with TAU 21 LTE EMM Procedure 10 & 11. Move to Another City and Attach 22 PCC LTE Policy and Charging Control (PCC) 23 Charging LTE Charging I: Offline 24 LTE Charging II: Online (TBD) 25 IP Address Allocation LTE IP Address Allocation Schemes I: Basic 26 LTE IP Address Allocation Schemes II: A Case for Two Cities
  3. 3. EMM Procedure 4. Service Request 2 Abbreviations AKA Authentication and Key Agreement AMBR Aggregated Maximum Bit Rate APN Access Point Name ARP Allocation Retention Priority AS Access Stratum ASME Access Security Management Entity C-RNTI Cell Radio Network Temporary Identifier CSG Closed Subscriber Group DL Downlink DRB Data Radio Bearer ECGI E-UTRAN Cell Global Identifier ECM EPS Connection Management EMM EPS Mobility Management eNB Evolved Node B EPS Evolved Packet System EPS-AKA Evolved Packet System – Authentication and Key Agreement E-RAB E-UTRAN Radio Access Bearer E-UTRAN Evolved Universal Terrestrial Radio Access Network GUMMEI Globally Unique MME ID GUTI Globally Unique Temporary Identifier HSS Home Subscriber Server IMSI International Mobile Subscriber Identity KSI Key Set Identifier LTE Long Term Evolution MAC Message Authentication Code MME Mobility Management Entity NAS Non Access Stratum O&M Operation and Maintenance PCC Policy and Charging Control PCRF Policy and Charging Rule Function P-GW Packet Data Network Gateway QCI QoS Class Identifier RRC Radio Resource Control S1AP S1 Application Protocol SDF Service Data Flow S-GW Serving Gateway SPR Subscriber Profile Repository S-TMSI SAE Temporary Mobile Subscriber Identity TAI Tracking Area Identity TEID Tunnel End Point Identifier TFT Traffic Flow Template UE User Equipment UL Uplink USIM Universal Subscriber Identity Module
  4. 4. EMM Procedure 4. Service Request 3 I. Introduction This document describes the service request procedure defined as EMM Case 4 in our technical document, “Eleven EMM Cases in an EMM Scenario” [1]. This procedure is performed when an inactive UE in Idle state wishes to get activated to handle traffic when there is new traffic. New user traffic can be uplink traffic from UE or downlink traffic from the network to UE. The UE’s E-UTRAN resources (allocated by eNB) have been released, and the UE has been in ECM/RRC-Idle state. Thus, in order for the UE to receive or send user traffic, DL or UL, it needs to transmit to ECM/RRC-Connected state through the service request procedure so that E- UTRAN resources can be allocated again. This document explains the service request procedure in an LTE network. Chapter II categorizes different cases of service request depending on where new traffic is generated. Chapter III and IV describe distinct procedures required in each service request case. Finally, Chapter V summarizes how information elements in EPS entities are different before and after the procedure. II. Cases of Service Request When a UE is still registered at a network, but its S1 connection is released due to inactivity, the UE has no radio resources available. That is, the UE is in EMM-Registered, but ECM-Idle state. If, at this time, new traffic is generated from the UE, or from the network to the UE, the UE requests the network for services, transmitting to ECM-Connected state. Then an ECM connection (RRC + S1 signaling connections) and E-RAB (DRB + S1 bearer) are setup in the control and user planes, respectively, allowing the UE to receive or send traffic. In case the network is sending out traffic to a UE, it first informs the UE of such intent so that the user can request for services. When the UE has new traffic to send, or learns about the network’s intent to send new traffic, it sends the MME a Service Request message, transmitting to ECM/RRC-Connected state. Then the UE, by using the allocated radio and network resources, can receive or send traffic. Service requests can be triggered by a UE or by a network, and can be categorized as follows depending on where the new traffic is generated:  Service Request Case 1: UE-triggered New Traffic When there is uplink data to be sent from UE to the network  Service Request Case 2: Network-triggered New Traffic When there is downlink data to be sent from the network to UE Figure 1 shows the connections established in the user and control planes, and the states of UE and MME, before and after the service request is made. Before the service request, the user is in EMM-Registered and ECM/RRC-Idle state. Thus, only the resources allocated by EPC are kept unreleased while those allocated by E- UTRAN are already released. In the control plane, S5 GTP-C and S11 GTP-C tunnels remain active while the ECM connection is lost. In the user plane, the S5 bearer and the uplink S1 bearer are kept active while the downlink S1 bearer and the DRB are released. After the service request, the UE, now with the allocated E-UTRAN resources, is in EMM-Registered and ECM/RRC-Connected. Also, we can see all of the bearers and connections in the EPS bearer (i.e. DRB, S1
  5. 5. EMM Procedure 4. Service Request 4 bearer and S5 bearer) and the signaling connection (i.e. ECM connection, S11 GTP-C and S5 GTP-C tunnels) are now established to support traffic delivery between the UE and the network (UE through P-GW). Figure 1. Connections and States before/after Service Request III. UE-triggered Service Request Figures 2 and 3 illustrate procedures for a UE-triggered service request caused by uplink traffic from UE. The NAS layer at the UE indicates to the MME that the UE has data to send out by sending a Service Request message. As a result, resources required for data transmission are allocated from the network. As the UE has stayed registered at the network, its NAS security context (KNASenc, KNASint, etc.) is kept valid at the UE and MME. With the context, the UE can send the Service Request as encrypted with the encryption key (KNASenc), and integrity-protected with the integrity key (KNASint). When the MME receives the message, it determines whether to perform authentication procedures for the user or not through integrity check and decryption of the message, and then the eNB establishes an E-RAB. eNB S-GWMME PCRFHSS SPRP-GWUE S5 BearerS1 BearerDRB ECM Connection S5 GTP-C ConnectionS11 GTP-C ConnectionS1 Signaling ConnectionRRC Connection ECM-Connected RRC-Connected EMM-Registered RRC-Connected ECM-Connected EMM-Registered 1) Connections and States before Service Request Control Plane Connection User Plane Connection (Bearer) States S5 GTP-C ConnectionS11 GTP-C Connection S5 BearerS1 Bearer ReleasedDRB Released ECM Connection Released S1 Signaling ReleasedRRC Released Control Plane Connection EMM-Registered EMM-Registered ECM-Idle RRC-Idle RRC-Idle ECM-Idle S1 TEID (UL) States User Plane Connection (Bearer) 2) Connections and States after Service Request
  6. 6. EMM Procedure 4. Service Request 5 Figure 2. Procedures for UE-triggered Service Request (1) ❶ ECM Connection Establishment When there is new traffic to send out, the UE sends the MME a Service Request message to establish an ECM connection. The Service Request message is delivered to the MME, through RRC connection established over radio link, and then through S1 signaling connection established between the eNB and the MME. In this document, we assume that a valid GUTI and NAS security context are kept at the UE and MME. 1), 2) [UE – eNB] RRC Connection Setup The NAS layer at the UE provides the RRC layer with S-TMSI. Then the RRC layer, by using this S-TMSI as a UE ID, sends a RRC Connection Request message to the eNB to set up RRC connection. The eNB returns a RRC Connection Setup message to the UE (see our document, Initial Attach [2] for more information). 3), 4), 5) [UE  MME] ECM Connection Setup Request The NAS layer at the UE sends a Service Request message to the MME to set up an ECM connection. The NAS security context associated with the UE has already been stored at the UE and MME. Thus, the message includes the NAS base key identifier (KSIASME), and is sent encrypted with the encryption key KNASenc and integrity-protected with the integrity key (NASint). This Service Request message is delivered to the eNB as included in a RRC Connection Setup Complete message over the radio link between the UE and eNB. Then it is sent as included in a S1AP message, Initial UE Message, from the eNB to the MME. At this time, the eNB allocates eNB UE S1AP ID, and includes it in the Initial UE [Optional] If NAS message is not Integrity Protected or Integrity Check Failed, MME triggers UE authentication eNB S-GWMME PCRFHSS SPRP-GWUE 3) Service Request KSIASME, NAS-MAC UE has the uplink data to be sent 1) RRC Connection Request 2) RRC Connection Setup 4) RRC Connection Setup Complete Ciphering and Integrity Protected for NAS message between UE and MME GUMMEI 5) Initial UE Message S-TMSI, ECGI, TAI S-TMSI S5 BearerS1 Bearer ReleasedDRB Released ECM Connection Released S5 GTP-CS11 GTP-CS1 Signaling ReleasedRRC Released ECM-Idle RRC-Idle EMM-Registered RRC-Idle ECM-Idle EMM-Registered Service Request Triggering 6) UE Authentication 7) NAS Security Setup Authentication Information Request/Authentication Information Answer Authentication Request/Authentication Response Security Mode Command/Security Mode Complete ECM Connection Establishment1 2 UE Authentication & NAS Security Setup (optional) UL Packet
  7. 7. EMM Procedure 4. Service Request 6 Message sent to the MME. Upon receiving the Initial UE Message, the MME allocates MME S1AP UE ID, and establishes an S1 signaling connection between the eNB and itself. ❷ UE Authentication and NAS Security Setup (Optional) 6) [UE – MME – HSS] UE Authentication After receiving the Service Request message from the UE, the MME performs integrity check on NAS- MAC. If the check passes, the MME can use the current NAS security context in transmitting NAS messages, without having to authenticate the UE again. However, if it fails, the MME performs authentication procedures for the UE through EPS-AKA1 . 7) [UE – MME] NAS Security Setup When the authentication is completed, both the UE and the MME generate the NAS security keys (KNASenc, KNASint) to be used in delivering NAS messages, through the NAS security setup procedure. Figure 3. Procedures for UE-triggered Service Request (2) 1 MME obtains authentication vectors for UE from HSS, and performs user authentication with the UE on behalf of the HSS. See our LTE Security document [3] for detailed procedures. [Optional] If ECGI or TAI is changed eNB S-GWMME PCRFHSS SPRP-GWUE Ciphering and Integrity Setup Complete for RRC message & Bearer 10) RRC Connection Reconfiguration EPS Bearer ID, DRB ID Create DRB IDReceive DRB ID DRB Established (UL/DL) 12) Initial Context Setup Response E-RAB ID, S1 eNB TEID Create S1 TEID (DL) 13) Modify Bearer Reqeust EPS Bearer ID, S1 eNB TEID, ECGI, TAI Receive S1 TEID (DL) S5 Bearer (UL/DL)S1 Bearer (UL)DRB (UL/DL) S1 Bearer Established (DL) S5 Bearer (UL/DL)S1 Bearer (UL/DL)DRB (UL/DL) 9) AS Security Setup (SMC) Modify Bearer Reqeust EPS Bearer ID, ECGI, TAI Indication of IP-CAN Session Modification (CCR) IMSI, UE IP, ECGI, TAI Acknowledge of IP-CAN Session Modification (CCA) Modify Bearer Response EPS Bearer ID EPS Bearer ID 16) Modify Bearer Response Internet Internet UL Packet to Internet at this time 11) UL Traffic Path Available 14) DL Traffic Path Available 8) Initial Context Setup Request Existing S1 TEID (UL)Receive S1 TEID (UL) S1 Bearer Established (UL) S5 BearerS1 BearerDRB ECM Connection S5 GTP-C ConnectionS11 GTP-C ConnectionS1 Signaling ConnectionRRC Connection ECM-Connected RRC-Connected EMM-Registered RRC-Connected ECM-Connected EMM-Registered UE-AMBR (UL/DL), E-RAB ID, E-RAB QoS (QCI, ARP), S1 S-GW TEID, KeNB 15) EPS Session Modification (optional) 3 E-RAB Establishment UL Packet UL Packet
  8. 8. EMM Procedure 4. Service Request 7 ❸ E-RAB Establishment After receiving the Service Request message from the UE, the MME has the eNB establish a DRB and a downlink S1 bearer through E-RAB establishment procedures. 8) [eNB  MME] Requesting E-RAB Establishment Upon receiving the Service Request message from the UE, the MME realizes that an E-RAB has to be established. So, it sends the eNB an Initial Context Setup Request message so that the eNB can set up an S1 bearer with the S-GW, and a DRB with the UE. At this time, the message includes the following information: Initial Context Setup Request (E-RAB ID, KeNB, S1 S-GW TEID, MME UE S1AP ID)  E-RAB ID  KeNB: the AS Security base key that enables eNB to set up AS Security with UE  S1 S-GW TEID: identifies the uplink S1 bearer connected to S-GW for eNB  MME UE S1AP ID: identifies the S1 signaling connection to MME for eNB 9) [UE – eNB] AS Security Setup After receiving the Initial Context Setup Request message from the MME, the eNB realizes that DRB and S1 bearer setup has to be performed in order for user traffic to be delivered. Before establishing a DRB, the eNB performs AS security setup procedures for secured communication with the UE through the SRB and DRB over the radio link (see our “LTE Security” document [3] for more information). The UE and the eNB derive KRRCint/KRRCenc to be used for integrity/encryption, and KUPenc to be used for user traffic encryption, through the AS security setup procedures. After the AS security setup is completed successfully, RRC messages to be delivered through the radio link are sent encrypted and integrity-protected, and user traffic is sent encrypted. Next, the eNB begins DRB establishment. 10) [UE  eNB] DRB Establishment The eNB allocates a DRB ID to create a DRB, an EPS bearer over the radio link, and sends a RRC Connection Reconfiguration message to the UE after configuring DRB QoS parameters for the message based on E-RAB QoS received from the MME. The UE, upon receiving the RRC Connection Reconfiguration message from the eNB, generates a DRB and SRB2. 11) UL Traffic Path Available Once a DRB is generated after Step 10), an uplink EPS bearer is set up from the UE all the way through the P-GW, allowing delivery of UE-generated uplink traffic. 12) 13) & 16) [eNB  S-GW] Setting up Downlink S1 Bearer In Step 12), the eNB allocates a downlink S1 TEID (S1 eNB TEID) for the S1 bearer, and forwards to the MME by including the ID in an Initial Context Setup Response message to be sent as a response to the Initial Context Setup Request it received in Step 8). In Step 13), the MME delivers an S1 eNB TEID as included in a Modify Bearer Request message to the S-GW, which establishes a downlink S1 bearer using the information. Then in Step 16), the S-GW informs the MME the establishment of the downlink S1 bearer through a Modify Bearer Response message. 14) DL Traffic Path Available Once Step 13) is performed, a downlink S1 GTP-U tunnel from the S-GW to the eNB is created,
  9. 9. EMM Procedure 4. Service Request 8 completing establishment of a downlink EPS bearer (all the bearers in the downlink) from the P-GW through the UE. This allows delivery of downlink traffic to the UE. 15) Modifying EPS Session (UE Location Registration) In case the UE’s current cell (ECGI) or TA has been changed at the time of service request, the S-GW sends the P-GW to inform such change. Then, the P-GW reports the same to the PCRF through EPS session medication procedure.2 IV. Network-triggered Service Request Figures 4 and 5 display procedures for a network-triggered service request procedure. This type of request is made when the network has downlink traffic to deliver to a UE in Idle state. The MME does not know the location of a UE which is in Idle state. So, it has to inform it has traffic to send to the UE through paging procedures, so that the bearer (E-RAB) resources that have been released can be established again. Figure 4. Procedures for Network-triggered Service Request (1) 2 During UE’s initial attach, PCRF can provide MME, S-GW and P-GW with its reporting policies on UE location changes through Change Reporting Action parameters included in a CCA message [2]. [Optional] If NAS message is not Integrity Protected or Integrity Check Failed, MME triggers UE authentication10) UE Authentication & NAS Security Setup Authentication Information Request/Authentication Information Answer Authentication Request/Authentication Response Security Mode Command/Security Mode Complete eNB S-GWMME PCRFHSS SPRP-GWUE S5 BearerS1 Bearer ReleasedDRB Released ECM Connection Released S5 GTP-CS11 GTP-CS1 Signaling ReleasedRRC Released ECM-Idle RRC-Idle EMM-Registered RRC-Idle ECM-Idle EMM-Registered S5 Bearer (UL/DL) Internet 7) Service Request KSIASME, NAS-MAC Network has the downlink data to be sent to the UE (Buffering) 5) RRC Connection Request 6) RRC Connection Setup 8) RRC Connection Setup Complete Ciphering and Integrity Protected for NAS message between UE and MME GUMMEI 9) Initial UE Message S-TMSI, ECGI, TAI 1) Downlink Data Notification 2) Downlink Data Notification Ack Send Paging to each eNB which belongs to the TAI(s) in which the UE is registered3) Paging S-TMSI, TAIs 3) Paging S-TMSI 4) Recognize Paging S-TMSI eNBeNBeNB Incoming DL Data EPS-bearer ID Service Request Triggering1 Paging2 ECM Connection Establishment3 4 UE Authentication & NAS Security Setup (optional) DL Packet
  10. 10. EMM Procedure 4. Service Request 9 ❶ Service Request Triggering If the S-GW receives downlink data packets from the P-GW through the S5 bearer, but cannot send them on to the eNB because the downlink S1 bearer is released (i.e. the S-GW does not have an S1 eNB TEID), it buffers the packets, and finds out at which MME the UE is registered. Then, the S-GW sends a Downlink Data Notification message to the MME to inform signaling connections and bearers need to be established for the UE. ❷ Paging The MME knows the UE is located in one of its TAs, but does not know in which cell the UE is. So, the MME sends a Paging message to all the eNBs in the TA the UE was in last time. The eNBs then broadcast the received Paging message, through its PCH (Paging Channel), so that the UE can receive it during its regular monitoring on the PCH. ❸ ECM Connection Establishment Becoming aware of incoming traffic, the UE sends a Service Request message, to establish an ECM connection. The procedure for ECM connection establishment begins when the UE accesses a cell through the radio access channel, and then sends an RRC Connection Request message to establish an RRC connection. It is performed as illustrated in Figure 2 (see detailed description given under Figure 2 for more information about ECM connection establishment). ❹ UE Authentication and NAS Security Setup (Optional) The MME, upon receiving the Service Request message from the UE, performs UE authentication procedures through EPS-AKA, and generates NAS security keys (NASint, NASenc) through NAS security setup procedures if the integrity check on NAS-MAC failed (see our LTE Security document [3] for detailed procedures).
  11. 11. EMM Procedure 4. Service Request 10 Figure 5. Procedures for Network-triggered Service Request (2) ❺ E-RAB Establishment After receiving the Service Request message from the UE, the MME establishes a DRB and downlink S1 bearer through E-RAB establishment procedures. Then, it is ready to receive data packets form the S-GW. The detailed procedures are the same as seen in Figure 3. [Optional] If ECGI or TAI is changed eNB S-GWMME PCRFHSS SPRP-GWUE Ciphering and Integrity Setup Complete for RRC message & Bearer 13) RRC Connection Reconfiguration EPS Bearer ID, DRB ID Create DRB IDReceive DRB ID DRB Established (UL/DL) 15) Initial Context Setup Response E-RAB ID, S1 eNB TEID Create S1 TEID (DL) 16) Modify Bearer Reqeust EPS Bearer ID, S1 eNB TEID, ECGI, TAI Receive S1 TEID (DL) S5 Bearer (UL/DL)S1 Bearer (UL)DRB (UL/DL) S1 Bearer Established (DL) S1 Bearer (UL/DL)DRB (UL/DL) 12) AS Security Setup (SMC) Modify Bearer Reqeust EPS Bearer ID, ECGI, TAI Indication of IP-CAN Session Modification (CCR) IMSI, UE IP, ECGI, TAI Acknowledge of IP-CAN Session Modification (CCA) Modify Bearer Response EPS Bearer ID EPS Bearer ID 19) Modify Bearer Response Buffered DL Packet to UE at this time 14) UL Traffic Path Available 17) DL Traffic Path Available 11) Initial Context Setup Request Existing S1 TEID (UL)Receive S1 TEID (UL) S1 Bearer Established (UL) S5 BearerS1 BearerDRB ECM Connection S5 GTP-C ConnectionS11 GTP-C ConnectionS1 Signaling ConnectionRRC Connection ECM-Connected RRC-Connected EMM-Registered RRC-Connected ECM-Connected EMM-Registered UE-AMBR (UL/DL), E-RAB ID, E-RAB QoS (QCI, ARP), S1 S-GW TEID, KeNB 18) EPS Session Modification (optional) 5 E-RAB Establishment Internet DL PacketDL Packet S5 Bearer (UL/DL)S1 Bearer (UL/DL)DRB (UL/DL) Internet Buffered DL Packet
  12. 12. EMM Procedure 4. Service Request 11 V. EPS Entity Information: Before/After Service Request This chapter looks into how information elements in the EPS entities are changed before and after the service request. All the information elements are categorized into UE ID, UE Location, Security, and EPS Session/Bearer information. 5.1 Before Service Request As explained in the EMM scenario document [1], before a service request is triggered, a UE transits from Active state to EMM-Registered and ECM/RRC-Idle state through S1 release. Therefore, all the information in the EPS entities after S1 release remain the same until the service request procedure is performed [4]. That is, information elements related to the radio resources allocated by E-UTRAN (eNB) and those related to the EPS bearer and signaling connection established in E-UTRAN (i.e. downlink S1 bearer and S1 signaling information) are now deleted from the EPS entities. In Figure 6, information elements stored in each EPS entity before a service request is triggered are marked in black. Figure 6. Information in EPS entities before Service Request SPRPCRFP-GWS-GWUE eNB IMSI GUTI UE IP address C-RNTI - - LTE K NAS Security Info AS Security Info ECGI TAI TAI List - APN in Use EPS Bearer ID DRB ID - - - QCI - - APN-AMBR (UL) TFT (UL) - IMSI GUTI UE IP address - eNB S1AP UE ID MME S1AP UE ID - NAS Security Info - APN in Use EPS Bearer ID - E-RAB ID S1 TEID (UL/DL) S5 TEID (UL/DL) QCI ARP UE-AMBR (UL/DL) APN-AMBR (UL/DL) - Subscribed Profile (Subscribed QCI, ARP, UE-AMBR, APN-AMBR) ECGI TAI TAI List - IMSI - - - - - LTE K - - - - - MME ID PCRF HSS SPR - - - C-RNTI eNB S1AP UE ID MME S1AP UE ID - - AS Security Info ECGI TAI - - - EPS Bearer ID DRB ID E-RAB ID S1 TEID (UL/DL) - QCI ARP UE-AMBR (UL/DL) - - - Default APN - - - - - - - - - - Subscribed Profile (Subscribed QCI, ARP, UE-AMBR, APN-AMBR) IMSI - - - - - - - - - - - - - - - - - - - Access Profile (Subscribed QCI, ARP, APN-AMBR) - - - - IMSI - UE IP address - - - - - - APN in Use - - - - - QCI* ARP* - APN-AMBR (UL/DL)* SDF Filter* - * PCC Rule ECGI TAI - - IMSI - UE IP address - - - - - - APN in Use EPS Bearer ID - - - S5 TEID (UL/DL) QCI* ARP* - APN-AMBR (UL/DL)* TFT (UL/DL)* - * PCC Rule ECGI TAI - - IMSI - - - - - - - - - EPS Bearer ID - - S1 TEID (UL/DL) S5 TEID (UL/DL) QCI ARP - - - - ECGI TAI - - S5 BearerData Radio Bearer S1 Bearer RRC Connection S1 Signaling Connection ECM ConnectionControl Plane S11 GTP-C S5 GTP-C eNB S-GW P-GWUE MME HSS MME User Plane S1 TEID (UL)
  13. 13. EMM Procedure 4. Service Request 12 5.2 After Service Request Once a service request is completed, a UE transits to ECM/RRC-Connected state, and an RRC connection/S1 signaling and E-RAB bearer (DRB + downlink S1 bearer) are established by E-UTRAN. As a result, all the information required for user traffic delivery between UE and P-GW is stored in EPS entities. Figure 7 lists information elements stored in each EPS entity after a service request is completed. These elements are the same as those stored after initial attach [2]. Figure 7. Information in EPS entities after Service Request SPRPCRFP-GWS-GWUE eNB IMSI GUTI UE IP address C-RNTI - - LTE K NAS Security Info AS Security Info ECGI TAI TAI List - APN in Use EPS Bearer ID DRB ID - - - QCI - - APN-AMBR (UL) TFT (UL) - IMSI GUTI UE IP address - eNB S1AP UE ID MME S1AP UE ID - NAS Security Info - APN in Use EPS Bearer ID - E-RAB ID S1 TEID (UL/DL) S5 TEID (UL/DL) QCI ARP UE-AMBR (UL/DL) APN-AMBR (UL/DL) - Subscribed Profile (Subscribed QCI, ARP, UE-AMBR, APN-AMBR) ECGI TAI TAI List - IMSI - - - - - LTE K - - - - - MME ID PCRF HSS SPR - - - C-RNTI eNB S1AP UE ID MME S1AP UE ID - - AS Security Info ECGI TAI - - - EPS Bearer ID DRB ID E-RAB ID S1 TEID (UL/DL) - QCI ARP UE-AMBR (UL/DL) - - - Default APN - - - - - - - - - - Subscribed Profile (Subscribed QCI, ARP, UE-AMBR, APN-AMBR) IMSI - - - - - - - - - - - - - - - - - - - Access Profile (Subscribed QCI, ARP, APN-AMBR) - - - - IMSI - UE IP address - - - - - - APN in Use - - - - - QCI* ARP* - APN-AMBR (UL/DL)* SDF Filter* - * PCC Rule ECGI TAI - - IMSI - UP IP address - - - - - - APN in Use EPS Bearer ID - - - S5 TEID (UL/DL) QCI* ARP* - APN-AMBR (UL/DL)* TFT (UL/DL)* - * PCC Rule ECGI TAI - - IMSI - - - - - - - - - EPS Bearer ID - - S1 TEID (UL/DL) S5 TEID (UL/DL) QCI ARP - - - - ECGI TAI - - S5 BearerData Radio Bearer S1 Bearer EPS Bearer RRC Connection S1 Signaling Connection ECM ConnectionControl Plane S11 GTP-C S5 GTP-C eNB S-GW P-GWUE MME HSS MME User Plane
  14. 14. EMM Procedure 4. Service Request 13 VI. Closing In this document, we have learned the service request procedure (“EMM Case 4” in [1]) required for re- allocation of E-UTRAN (eNB) resources as new traffic arrives to a UE which has stayed in Idle state in the network it accessed. We have also summarized the user information elements that are stored in EPS entities when an end-to-end EPS bearer is established through a service request procedure. When a UE transits to Idle state while still being registered at the network, its EPC resources are kept, but E-UTRAN resources are released. Thus, a DRB has to be re-established as in attach request. However, in case of an S1 bearer, only a downlink S1 bearer needs to be re-established unlike attach request, allowing faster traffic delivery. The subsequent document will discuss procedures required when a UE in Idle state performs Tracking Area Updates (TAUs) regularly (“EMM Case 5: Periodic TAU” in [1]). References [1] Netmanias Technical Document, “Eleven EMM Cases in an EMM Scenario”, October 2013, http://www.netmanias.com/en/?m=view&id=techdocs&no=6002 [2] Netmanias Technical Document, “LTE EMM Procedure 1. Initial Attach – Part 2. Call Flow of Initial Attach”, January 2014, http://www.netmanias.com/en/?m=view&id=techdocs&no=6102 [3] Netmanias Technical Document, “LTE Security II: NAS and AS Security”, August 2013, http://www.netmanias.com/en/?m=view&id=techdocs&no=5903 [4] Netmanias Technical Document, “LTE EMM Procedure 3. S1 Release”, January 2014, http://www.netmanias.com/en/?m=view&id=techdocs&no=6110 [5] NMC Consulting Group Confidential Internal Report, “E2E LTE Network Design”, August 2010
  15. 15. EMM Procedure 4. Service Request About NMC Consulting Group NMC Consulting Group is an advanced and professional network consulting company, specializing in IP network areas (e.g., FTTH, Metro Ethernet and IP/MPLS), service areas (e.g., IPTV, IMS and CDN), and wireless network areas (e.g., Mobile WiMAX, LTE and Wi-Fi) since 2002. Copyright © 2002-2014 NMC Consulting Group. All rights reserved. Carrier WiFi Data Center Migration Wireline Network LTE Mobile Network Mobile WiMAX Carrier Ethernet FTTH Data Center Policy Control/PCRF IPTV/TPS Metro Ethernet MPLS IP Routing 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 eMBMS/Mobile IPTV Services CDN/Mobile CDN Transparent Caching BSS/OSS Cable TPS Voice/Video Quality IMS LTE Backaul Netmanias Research and Consulting Scope Visit http://www.netmanias.com to view and download more technical documents.

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