Mobile NW Architecture Evolution

Mobile NW Architecture Evolution Prof. Tarik Taleb School of Electrical Engineering Aalto University Mobile Generations AMPS, NMT, TACS 1G 2G 3G 4G ~1980 ~1990 ~2000 ~2010 The foundation of mobile telephony GSM, IS-136, PDC, IS-95 WCDMA cdma2000 Mobile telephony The foundation of for everyone mobile broadband LTE Further enhanced mobile broadband IMT-2000 IMT-Advanced 1

Global LTE Commitments Mobile Network Architecture Evolution 2

Outline Brief Intro to 3GPP Legacy Networks: GSM GPRS UMTS System Architecture Evolution Background & requirements Motivation Basic principles Network elements and high level functions Architectural enhancements for E-UTRAN and interoperability with 3GPP and non-3gpp accesses Interoperability Mobility and handover management Policy Control and Charging (PCC) QoS Provisioning Main References: 1-3GPP Technical Specifications 23.401 2-3GPP Technical Specifications 23.402 3GPP Access Evolution 2G or GSM/CS Voice communication narrowband, real-time, circuit switched WAP or HSCSD as extensions to enable data communications but limited success 2.5G (GPRS/PS, Enhanced Data Rates for GSM Evolution EDGE) Adding Packet Services Theoretical data rates up to 384 Kbps Not always-on IP connectivity: IP address is assigned only when PDP context is established for data transmission 3G or UMTS Built on WCDMA High peak data rates: 2Mbps Extended by HSDPA (Rel. 5), HSUPA (Rel. 6), and HSPA+ (Rel. 7) IMS as service control layer for PS core network Beyond 3G Long Term Evolution (LTE) LTE-Advanced 5G NR 3

Release of 3GPP Specifications LTE DL: 0.3Gbps UP: 75Mbps LTE- Advanced DL: 1Gbps UP: 0.5Gbps 1999 UMTS 2 Mbps HSDPA DL: 14.4 Mbps UP: 384 Kbps 2002 2004 HSUPA DL: 14.4 Mbps UP: 5.7 Mbps HSPA+ DL: 28 Mbps UP: 11 Mbps 2007 2008 2011 UMTS (W-CDMA) HSDPA HSUPA HSPA+ LTE LTE- Advanced Rel 99 Rel 5 Rel 6 Rel 7 Rel 8 SAE Rel 10 W-CDMA EDGE GPRS Wideband Code Division Multiple Access Enhanced Data rates for Global Evolution General Packet Radio Service Presentation Focus Rel9 GSM Global System for Mobile Communications LTE Long Term Evolution HSUPA High Speed Uplink Packet Access HSDPA UMTS High Speed Downlink Packet Access Universal Mobile Telecommunications System Nomenclature (1) Long Term Evolution Evolved UMTS Radio Access (E- UTRA) (Physical and link layers) E-UTRA Network (E-UTRAN) Radio Network s Functions Evolved Packet Core System Architecture 4

Nomenclature (2) Evolved 3GPP System System Architecture Evolution (SAE) Evolved Packet System (EPS) EPS = Evolved UTRAN + Evolved Packet Core 3G+, 3.5G, 4G, 5G,etc Advanced phases of the system design Marketing terms Legacy 3GPP Networks 5

GSM 2G Architecture PSDN SS7 ISUP MAP/IS41 (over TCAP) Um SS7 SMS-SC IAM A 2G MS BSC MSC Abis B VLR BTS D In case of roaming GERAN GSM EDGE Radio Access EIR Network E Routing Info PLMN C PSTN GMSC Subscriber s location? H HLR AuC PSTN, ISDN BTS Base Transceiver Station BSC Base Station Controller MS Mobile Station NSS Network Sub-System MSC Mobile-service Switching Controller VLR Visitor Location Register HLR Home Location Register AuC Authentication Server GMSC MSC EIR Equipment Identity Register PLMN PSDN PSTN PSPDN CSPDN ISDN Public Land Mobile Network Public Switched Data Network Public Switched Telephone Network Packet Switched Public Data Network Circuit Switched Public Data Network Integrated Services Digital Network Circuit Switch vs Packet Switch Reserved bandwidth Time based billing Fixed access time Suitable to real-time applications Lower bit rates (14.4 kbps) Inefficient use of resources Shared bandwidth Traffic based billing Variable access times Ideal for data traffic Higher bit rates (up to 170 kpbs) 2.5 G (GPRS) GPRS General Packet Radio Service 6

GPRS Architecture Um SS7 2.5G MS Abis BTS BSC Packet Data Protocol (PDP) context: 1) PDP type Gb 2) PDP address (for MS) 3) Requested QoS 4) GGSN address A MSC Gs SGSN B VLR EIR IP Gr D E PLMN HLR/ HSS Gn H Gc C AuC GMSC GGSN Gx PSTN PCRF Rx Gi PSTN, ISDN PSDN GPRS General Packet Radio Service SGSN Serving GPRS Support Node GGSN GPRS Support Node HSS Home Subscriber Server PCRF Policy Charging & Rules Function 1- Packet routing from/to MS/GGSN 2- Mobility management 3- Authentication 4- Billing 1- Interfaces to external PDNs 2- Translation between PDP context and GSM adds 3- Authentication 4- Billing UMTS Architecture (3G Rel 99) Um SS7 2.5G MS Abis BTS BSC A MSC B VLR D E PLMN C GMSC PSTN PSTN, ISDN 3G UE Uu Iub RNC Gb IuPS IuCS Gs SGSN EIR IP Gr HLR/ HSS Node B Radio Resource Management at UE and RNC: 1) Handover control 2) Power control 3) Admission control UTRAN UMTS Terrestrial Radio Access 4) Packet scheduling Network 5) Code management Gn H Gc AuC PCRF Gx Rx GGSN Gi PSDN UMTS Universal Mobile Telecommunication System UE User Equipment RNC Radio Network Controller 7

UMTS Architecture (3G Rel 5) Um IP/ATM 2.5G MS BSC A /IuCS Abis BTS ATM Gb /IuPS MSC Gs B VLR SS7 D HLR/ HSS Nb/Nc H C GMSC PSTN/CS- MGW PSTN, ISDN Uu IuCS Gr Gc AuC Gx PCRF Rx 3G UE Iub RNC IuPS SGSN Gn GGSN Gi PSDN Node B Gs IP Multimedia Sub System (IMS) Long Term Evolution 8

LTE Features & Requirements Always on IP connectivity All-IP Network (AIPN) Providing economy of scale and spectrum reuse Supporting full mobility and global roaming Ensuring seamless service across different radio access Efficiently interworking with non-3gpp accesses Compatible with legacy 3GPP networks Ensuring high QoS Affording high user data rates for both uplink and downlink Lower latencies in user data and control planes Supporting diverse mobile network services, both unicast and multicast System with reduced cost (CAPEX and OPEX) Reduced number of network elements flatter architecture Less complexity in RAN and economic usage of backhaul capacity System with improved capacity and coverage Usage of the orthogonal frequency-division multiplexing (OFDM) Spectrum efficiency and reuse System with high level of security LTE history - Workplan First release of Evolved UTRAN + Evolved Packet Core = Evolved Packet System was standardized in 3GPP Release 8 Official freeze of architecture work for Rel-8 was in June 2008 Start of All IP Networks Start of Study Architecture Study Start of Normative Work 2004 2005 2006 2007 2008 2009 2010 2011 9

System Architecture Study Objectives: address architecture impacts stemming from All-IP Network study (TR 22.978) define Evolved Packet Core (EPC) for LTE support mobility between heterogeneous access networks, including service continuity Key Features/Requirements Simple protocol architecture Shared channel based PS mode only with VoIP capability (No CS) Simple Architecture enodeb as the only E-UTRAN node Fully meshed approach with tunneling mechanism over IP transport network Iu Flex approach Smaller number of RAN interfaces enodeb MME/SAE- (S1) enodeb enodeb (X2) Compatibility and inter-working with earlier 3GPP Releases Inter-working with other systems, e.g. cdma2000 FDD and TDD within a single radio access technology Efficient Multicast/Broadcast Single frequency network by OFDM Support of Self-Organizing Network (SON) operation 3GPP TS 22.278 Tech. Spec., Service Requirements for Evolution of the 3GPP System, Stage 1, Release 8, June 2008 10

History on Architecture Battles (1) Architecture A Architecture B GERAN UTRAN Layer-2 like Evolved RAN Iu Gb R1 AAA interface WLAN 3GPP IP Access SGSN Gn/Gp Evolved Packet Core HSS Gx+ R2 PCRF1 Gi Tight coupling to legacy Based on IP-based Mobility Protocols (IETF-based) Gi Op. IP Serv. (IMS, PSS, etc) Op. IP Serv. (IMS, PSS, etc) Internet Mobility between access networks based Wi on 3GPP protocols (e.g. GTP) Internet Gi+ Inter-AS MM Gi+ Gi Gi GPRS Core PCRF2 Wi+ HSS Gb Iu AAA interface GERAN UTRAN Evolved Evolved Packet Core Evolved RAN Access Gi Internet Wi Gi WLAN 3GPP IP Access Loose coupling to legacy Layer-3 like History on Architecture Battles (2) Mobility hsae GW Anchor GTP vs. IP-based Mobility HPLMN S2a/b (PMIP) VPLMN S8a (GTP) S8b (PMIP) legacy PMIP: Proxy Mobile IP GTP: GPRS Tunneling Protocol vsae GW MME UPE S2a/b non-3gpp (GTP or PMIP) 11

Control Plane Data Plane 9/10/2018 Architectural Aspects of EPC 3GPP accesses non-3gpp accesses Untrusted non-3gpp Requirement for a special gateway (evolved Packet Data ) for a secure access of UE to EPC Trusted non-3gpp epdg not required EPS for 3GPP Accesses PDN GW: IP address allocation, charging and enforces QoS Serving GW: Local mobility anchor for intra-3gpp HO MME: Mobility management entity for intra-3gpp mobility, paging, authentication, bearer management, etc. PCRF: QoS and charging rule provisioning VPLMN HPLMN UTRAN 3GPP Access GERAN S1-MME SGSN MME S3 S4 S12 Gxc S6a Gx HSS PCRF Rx UE LTE-Uu E-UTRAN S1-U S10 S11 Serving PDN Packet Data Network (e.g. IMS, PSS etc.) GTP Interface GTP or PMIP Interface PCC Interface 12

Control Plane Data Plane 9/10/2018 EPS for 3GPP Accesses PDN GW: IP address allocation, charging and enforces QoS Serving GW: Local mobility anchor for intra-3gpp HO MME: Mobility management entity for intra-3gpp mobility, paging, authentication, bearer management, etc. PCRF: QoS and charging rule provisioning VPLMN HPLMN UTRAN UE LTE-Uu 3GPP Access E-UTRAN GERAN S1-MME S1-U SGSN MME S3 3GPP Access S10 S11 S6a S12 S4 Serving HSS S6a PCRF Gx PDN Rx Operator's IP Services (e.g. IMS, PSS etc.) GTP Interface GTP or PMIP Interface PCC Interface PDN Functions S1-MME MME UE LTE-Uu E-UTRAN S1-U S10 S11 Serving PDN Operator's IP Services (e.g. IMS, PSS etc.) UE IP address allocation UE data anchoring Per user packet filtering Lawful interception Transport level packet marking Service level charging Service level gating control Rate enforcement based on Aggregate Maximum Bit Rate for an APN Accumulated Maximum Bit Rates of the aggregate of service data flows with the same guaranteed bit rate DHCPv4 & DHCPv6 functions GTP-based Up/Downlink bearer binding Uplink bearer binding verification IP neighborhood detection 13

Control Plane Data Plane Control Plane Data Plane 9/10/2018 Serving Functions S1-MME MME UE LTE-Uu E-UTRAN S1-U S10 S11 Serving PDN Operator's IP Services (e.g. IMS, PSS etc.) PMIPv6 MAG functionality Inter-eNB handover Downlink packet buffering in idle mode Service Request Lawful Interception Packet routing and forwarding Up/Downlink packet marking Accounting for inter-operator charging Up/Downlink charging MME Functions S1-MME MME UE LTE-Uu E-UTRAN S1-U S10 S11 Serving PDN Operator's IP Services (e.g. IMS, PSS etc.) Handling of NAS signaling - En/decryption and authentication of messages Support of UE Reachability in idle state Tracking Area management; PDN/S-GW selection Target MME selection Subscriber authentication Bearer management Lawful Interception of signaling traffic 14

Control Plane Data Plane 9/10/2018 Evolved RAN S1-MME MME UE LTE-Uu E-UTRAN S1-U S10 S11 Serving PDN Operator's IP Services (e.g. IMS, PSS etc.) enb X2 enb Radio Resource Management - Radio Bearer Control Iups - Radio Admission Control - Connection Mobility RNControl - Scheduling Iub Iub IP header compression and encryption of data traffic NB NB MME selection the user data stream Data packet routing UTRAN Uplink transport level packet marking Scheduling and transmission of - paging messages - broadcast information Measurement for mobility and scheduling Tracking Areas, Service Areas, & MME Pool Areas MME MME Pool Area PDN-GW 1 PDN-GW m S-GW 1 S-GW 2 S-GW k Service Area 1 Service Area 2 Service Area K enbs Tracking Area enbs Tracking Area 2 enbs Tracking Area 3 enbs Tracking Area N Tracking Area Update S-GW Relocation MME Relocation 15

LTE UE Identifiers UE IMEI or MEID - Mobile Equipment Identifier Globally unique number identifying a physical piece of mobile station equipment MEID allows hexadecimal digits while IMEI (Int l Mobile Station Equipment Identity) allows only decimal digits Only sent to MME (in NAS), not to enb. Sent only after NAS security is setup (i.e, encrypted and integrity protected). SIM (Subscriber Identity Module) HD: Universal Integrated Circuit Card (UICC) SW: USIM Universal Subscriber Identity Module IMSI Seldom sent over the air (only during attach, if no other valid temporary ID is present in the UE). Temporary identities used instead (S-TMSI, GUTI) Brought, among other things, security improvements (e.g., mutual authentication, longer encryption keys, etc) S-TMSI GUTI System architecture evolution Temporary Mobile Subscriber Identity Globally Unique Temporary Identity Initial Attach 16

UE ID Acquisition GUMMEI ECGI TAI IMSI Globally Unique MME Identity E-UTRAN Cell Global Identifier Tracking Area Identity International Mobile Subscriber Identity Authentication ASME MCC MNC AUTN KSI Access Security Management Entity (MME) Mobile Country Code assigned by ITU, 3 digits Mobile Network Code assigned by National Authority, 2~3 digits Authentication TokeN Key Set Identifier 17

NAS Security Setup ASME KSI NAS Access Security Management Entity (MME) Key Set Identifier Non-Access Stratum Location Update QCI: QoS Class Indicator ARP: Allocation and Retention Priority AMBR: Aggregate Maximum Bit Rates 18

EPS Session Management (1/2) IP-CAN IP Connectivity Access Network EPS Session Management (2/2) 19

Information Elements: Before Attach Information Elements: After Attach http://www.netmanias.com/en/post/techdocs/6098/emm-initial-attach-lte/emm-procedure-1- initial-attach-part-1-cases-of-initial-attach 20

Some Nomenclature Reference Points & Protocols enb-involved signaling: (over S1-AP) Attachment, detachment, bearer establishment/modification, etc Signaling transparent to enb: - on top of Non-Access Stratum (NAS) UE NAS LTE-Uu E-UTRAN S1-MME S1-U MME S10 NAS RRC PDCP RLC S11MAC L1 UE S6a MAC Serving L1 LTE-Uu RRC PDCP RLC HSS Relay enodeb S1-AP SCTP IP L2 L1 Gx PDN PCRF Rx NAS S1-AP SCTP IP Operator's IP L2 Services L1 (e.g. IMS, PSS etc.) S1-MME MME RRC Radio Resource Control PDCP Packet Data Convergence Protocol L2 L1 Encapsulation or tunneling of packets over GTP-U 21

Reference Points & Protocols For exchange of UE subscription data (Diameter) - IPv4/IPv6 for packet forwarding - DHCP and RADIUS/DIAMETER for IP address and protocol configuration HSS NAS S1-MME MME S6a Gx PCRF Rx UE LTE-Uu E-UTRAN S1-U S10 S11 Serving PDN Operator's IP Services (e.g. IMS, PSS etc.) For MME relocation due to UE mobility or load balancing (GPT-C) For controlling data bearer between enb and SGW (GTP-C v2) -Used when PGW and SGW are in HPLMN - Based on either GTP or PMIP Reference Points & Protocols UTRAN For filtering QoS policy and charging control (DIAMETER) Gxc: used when PMIP is used on SGSN Gn/Gp NAS GERAN S1-MME S3 MME S13 EIR S6a S4 S12 HSS Gxc Gx PCRF Rx UE LTE-Uu E-UTRAN S1-U S10 S11 GGSN Serving GGSN PDN Operator's IP Services (e.g. IMS, PSS etc.) Enables user/bearer info exchange for inter-3gpp access mobility (GTP-U) enables UE identity check between MME and EIR Provides mobility support between GPRS and SGW Allows direct tunnel between S-GW and RNC (GTP-U) 22

A-GW: Access gateway for Trusted non-3gpp access epdg: Security GW for untrusted non 3GPP acess HPLMN Non-3GPP Networks 3GPP Access EPS for non-3gpp Accesses Serving PCC Interface PMIP or GTP Interface PMIP Interface AAA Interface S6a No No GTP GTP bearers, bearers! only PMIPv6 tunnels HSS Gxc PDN S2a S2b Gx PCRF Gxa epdg Rx SWx Operator's IP Services (e.g. IMS, Internet) S6b SWm 3GPP AAA Server SWn - Local IP address allocation - IP Sec tunnel authentication and A-GW authorization SWu Untrusted - IP packets en/decapsulation Non-3GPP Trusted Non-- Transport level Access packet marking SWain STa 3GPP Accessuplink - QoS enforcement UE - Lawful interception Summary Migration scenarios from legacy NWs to EPS LTE Requirements & History EPS Architecture, Components, and Protocols Next Lecture Core Aspects: Interoperability Mobility and handover management Policy Control and Charging (PCC) QoS Provisioning Security 23