3GPP Telecommunication Systems Long Term Evolution (LTE) Gert-Jan van Lieshout Samsung Electronics Research Institute Deventer, The Netherlands gert.vanlieshout@samsung.com 2012-06-05 Mobile and Wireless; 23-10-2014
Outline Outline Introduction [4]-[9] � 3 rd Generation Partnership Project (3GPP) � Start of LTE � Overall LTE architecture � LTE RAN: “E-UTRAN” [11]-[34] � E-UTRAN Release-8 � � E-UTRAN architecture � User Plane protocol Stack � Control Plane protocol Stack � Specific Features: Quality of Service � Mobility � E-UTRAN after Release-8 � LTE Core Network: “EPC” [36]-[54] � Core Network Architecture � Signalling Sequence Examples � PS CN evolution � Interworking with non-3GPP accesses � Summary [56] � 2 Mobile and Wireless; 23-10-2014
I Introduction Mobile and Wireless; 23-10-2014
3GPP structure 3 rd Generation Partnership Project (3GPP) (Europe) (USA) (Korea) (China) (Japan) (Japan) www. 3gpp.org 4 Mobile and Wireless; 23-10-2014
Why LTE ? Competition situation around 2006: � GSM did not have any serious competition a decade � Even today, still the unchallenged nr. 1 in number of mobile phones � UMTS had competition from the beginning but won � CDMA-2000 (3GPP2 evolution “UMB” on side-track) � More data centric solutions are standardised by IEEE: � 802.16 � Mainly backhaul broadband wireless (OFDM, nomadic) � 802.16e (“WiMax”) � Broadband wireless access to end-users (OFDM, with mobility support) � Large group of supporters (Samsung, Intel, ….) � Flatter architecture (2 nodes) => Cheaper � 802.20 � Also based on OFDM with mobility support � Can HSDPA/EDCH meet the WiMax competition ? (=> Yes) � 3GPP answer: “Long Term Evolution” (LTE) 5 Mobile and Wireless; 23-10-2014
Why LTE ? LTE & EPC � Around 2006, 3GPP RAN groups start to work on LTE “Long Term Evolution”. In parallel SA2 started to work on the EPS ‘Evolved Packet System’ started. � Main objectives: � Ensure competitiveness in the next 10 years and behond � Enhanced capability of 3GPP system to cope with rapid growth of IP data traffic � Support for (seamless) mobility between heterogeneous access networks � Important parts of such a long-term evolution included: � Reduced latency, higher user data rates, improved system capacity and coverage, and reduced overall cost for the operator � “flat IP Architecture” � LTE/SAE system was to be packet only system � Migration aspects were to be taken into account for the above, i.e. how to migrate from the existing architecture � Resulted in 2 new main architecture documents: � 23.401: GPRS enhancements for E-UTRAN � 23.402: Architecture enhancements for non-3GPP accesses 6 Mobile and Wireless; 23-10-2014
LTE: Overall architecture Overall network architecture (non roaming) Source: TS23.401 7 Mobile and Wireless; 23-10-2014
LTE: Basic principle Uu (radio) interface: Terminal to Network UE Network / “Infrastructure side” Uu 8 Mobile and Wireless; 23-10-2014
LTE: Basic principle S1 interface: Separates RAN from CN Non-Access Stratum (NAS) functionality - no radio specific functionality Access Stratum (AS) , Radio Network functionality - all radio specific functionality - no user service specific functionality UE E-UTRAN CN S1 Uu 9 Mobile and Wireless; 23-10-2014
E-UTRAN II E-UTRAN Release-8 • E-UTRAN architecture • User Plane protocol Stack • Control Plane protocol Stack • Specific Features: • Quality of Service • Mobility E-UTRAN beyond Release-8 • Release-10: Carrier Aggregation • Release-11 • Release-12 … Mobile and Wireless; 23-10-2014
E-UTRAN architecture E-UTRAN Architecture � E-UTRAN consists of eNBs � flat architecture (no RNC or BSC as in UTRAN and GERAN) for reduced latency and delays � eNBs are interconnected with each MME / S-GW MME / S-GW other by means of the X2 interface � can be a logical connection via CN elements S1 S1 S1 1 � eNBs are also connected to the Evolved S X2 E-UTRAN Packet Core (EPC) eNB eNB X2 X2 � eNBs are connected to the Mobility Management Entity (MME) via the S1-C (control) interface eNB � eNBs are connected to the to the Serving Uu Gateway (S-GW) by means of the S1-U (user data) interface 11 Mobile and Wireless; 23-10-2014
E-UTRAN architecture E-UTRAN Functions � Main functions hosted by eNB include � Functions for Radio Resource Management: � Connection Mobility Control, eNB � Radio Bearer Control, Inter Cell RRM � Radio Admission Control, RB Control � Dynamic allocation of resources Connection Mobility Cont. MME to UEs in both uplink and Radio Admission Control downlink (scheduling) NAS Security eNB Measurement � IP header compression and Configuration & Provision Idle State Mobility encryption of user data stream Handling Dynamic Resource Allocation (Scheduler) � Routing of User Plane data EPS Bearer Control RRC towards Serving Gateway PDCP � Scheduling and transmission S-GW P-GW RLC of paging messages Mobility UE IP address Anchoring allocation MAC (originated from the MME); S1 PHY Packet Filtering � Scheduling and transmission of internet broadcast information (originated E-UTRAN EPC from the MME or O&M) 12 Mobile and Wireless; 23-10-2014
E-UTRAN protocol stack: User Plane UE eNB User Plane protocol stack (1) PDCP PDCP RLC RLC � PDCP (Packet Data Convergence Protocol) – 36.323 MAC MAC PHY PHY ciphering � timer-based discard and header compression using the RoHC protocol � in-sequence delivery, retransmission and duplicate detection of PDCP SDUs at handover � Radio Bearers � RLC (Radio Link Control) – 36.322 ROHC ROHC reliability increase through retransmissions � PDCP Security Security segmentation and concatenation of SDUs for the � same radio bearer in-sequence delivery � Segm. Segm. ... RLC ARQ etc ARQ etc � MAC (Media Access Control) – 36.321 Logical Channels multiplexing/demultiplexing of RLC PDUs � Scheduling / Priority Handling scheduling information reporting � error correction through HARQ MAC Multiplexing � logical channel prioritisation � HARQ Transport Channels UL-SCH 13 Mobile and Wireless; 23-10-2014
E-UTRAN protocol stack: User Plane User Plane protocol stack (2) IP PDU#1 IP PDU#2 IP PDU#2 Radio Bearer 1 Radio Bearer 1 Radio Bearer 2 Header IP Payload Header IP Payload Header IP Payload H H H PDCP SN PDCP SDU SN PDCP SDU SN PDCP SDU RLC SDU RLC SDU RLC SDU RLC H H H RLC PDU RLC PDU MAC H MAC SDU MAC SDU Multiplexing PHY Transport Block CRC 14 Mobile and Wireless; 23-10-2014
E-UTRAN protocol stack: Control Plane Control Plane protocol stack (1) � RRC (Radio Resource Control) – 36.331 � Broadcast of system information, paging, RRC connection management, RB control, mobility functions, UE measurement reporting and control � PDCP (Packet Data Convergence Protocol) – 36.323 � Ciphering and integrity protection UE eNB MME NAS NAS RRC RRC PDCP PDCP RLC RLC MAC MAC PHY PHY 15 Mobile and Wireless; 23-10-2014
E-UTRAN protocol stack: Control Plane Control Plane protocol stack (2) � Only two RRC states � IDLE and CONNECTED � (Compare to IDLE, CELL_PCH, CELL_FACH, CELL_DCH in UMTS) � Idle mode � UE known in EPC, not in EUTRAN � UE has an IP address and its location known on Tracking Area level � UE-based cell-selection and tracking area update to EPC � MME initiates paging in the whole tracking areas indicated by the UE � Connected mode � Unicast data communication possible � UE known in E-UTRAN and its location known on Cell level � Mobility is UE-assisted, network-controlled � Discontinuous Data Reception (DRX) supported for power saving 16 Mobile and Wireless; 23-10-2014
E-UTRAN Mobility Control Plane protocol stack (3) UE1 -> UE2 -> Core Network S1-Conn. Y TA 403 S1 S1 S1-connection Y TA 403 eNB (Tracking Area) UE1 -> Cell X = Data record RRC-connection X Cells TA 403 (Tracking Area) Uu (the “radio interface”) UE 1, Connected C h 4 a n s n e l a a C q s k h 4 a w l d n s s n e e d j l a a a a f f q s k q s k r l w l d UE 2, Idle mode mode w l d r ö ö s s e d j e d j t a a a a a f f f f i d l q s k q s k r r l u a w l d w l d r r ö ö o ö d s e d j e d j t a l k a a f f f f i d l d k s q s k r r u a k d f w l d r r o ö d l j e d j l k c f f d k s r k d f r l j c 17 Mobile and Wireless; 23-10-2014
E-UTRAN QOS End-to-End QOS E-UTRAN EPC Internet UE eNB S-GW P-GW Peer Entity End-to-end Service EPS Bearer External Bearer E-RAB S5/S8 Bearer Radio Bearer S1 Bearer Radio S1 S5/S8 Gi � E-UTRAN is responsible for Radio Bearer management and therefore ensuring QoS over the radio � one-to-one mapping between EPS bearer, E-RAB and Radio Bearer 18 Mobile and Wireless; 23-10-2014
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