3GPP LTE/ Networks - Introduction to Cellular Networks -

Kyunghan Lee Networked Computing Lab (NXC Lab) Department of Electrical and Computer Engineering Seoul National University https://nxc.snu.ac.kr [email protected]

WIRELESS NETWORKING, 430.752B, 2020 SPRING AdaptedSEOUL from NATIONALProf. Sunghyun UNIVERSITYChoi’s slides 5 WirelessRoadmap Networks - Roadmap

IMT-Advanced Mobility Standard LTE-A Pro 2015 2010 Rel. 13/14 1995 2000 2005 High LTE-A (Up to 350 km/h) Rel. 10-12 *Rel. 13 (03/2016) LTE 3G Ev. IEEE IEEE 802.20 802.16m W-CDMA MBWA CDMA AMPS HSDPA/HSUPA GSM CDMA2000/Ev-DV/DO Medium IEEE (Vehicular) 802.16e WiBro/M-WiMAX F-WiMAX

IEE 802.11ac IEEE VHT Low 802.16 a/d 802.11n (Nomadic) IEEE WLAN 802.11a/b

14.4 kbps 144 kbps 384 kbps ~50 Mbps ~100 Mbps ~1 Gbps Peak Data Rate

WIRELESS NETWORKING, 430.752B, 2020 SPRING MWNL SEOUL NATIONAL UNIVERSITY Multimedia & Wireless Networking Lab. Wireless Networks - Roadmap

Source: https://semiengineering.com/should-we-even-be-talking-about-6g/

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY History

□ LTE (Long Term Evolution) § LTE is 3GPP system for the years 2010 to 2020 and beyond § It must keep the support for high mobility users like in GSM/UMTS § LTE(-A) is the latest standard in the mobile network technology tree that previously realized the GSM/EDGE and UMTS/HSPA network technologies

□ LTE–Advanced § LTE-A is often used for LTE Release 10 and beyond § Formal name is Advanced E-UTRA (evolved universal terrestrial radio access) § Cost-efficient support for backward and forward compatibility between LTE and LTE-A

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Standardization for LTE-A

□ 3GPP (Third Generation Partnership Project) § 3GPP was to make a globally applicable third-generation (3G) mobile phone system specification based on evolved Global System for Mobile Communications (GSM) within the scope of the IMT-2000 project § Organizational partners • ETSI (Europe), T1 (USA), TTA (Korea), TTC (Japan), CWTS (China)

https://www.qualcomm.com/ news/onq/2017/08/02/

3GPP Organization Structure 3GPP Organization understanding--starting-basics

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Motivation

□ Need for higher data rates and greater § New defined by 3GPP LTE □ Need for packet switched optimized system § Evolve UMTS towards packet only system

□ Need for high quality of services (QoS) § Use of licensed frequency to guarantee QoS § Reduce round trip delay □ Need for cheaper infrastructure § Simplify architecture § Reduce number of network elements

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Terminology

□ LTE (Long Term Evolution) § Evolution of 3GPP Radio Access Technology § E-UTRAN (Evolved Universal Terrestrial Radio Access Network)

□ SAE (System Architecture Evolution) § Evolution of 3GPP Core network technology (started from 3GPP rel.8) § EPC (Evolved Packet Core) • No more consideration for circuit switching (GSM) or circuit/packet dual (GPRS, UMTS)

□ EPS (Evolved Packet System) § Evolution of the complete 3GPP UMTS Radio Access, Packet Core and its integration into legacy 3GPP/non-3GPP networks § E-UTRAN + EPC

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Overview of LTE Design Benefits

□ New architecture § Flat architecture: one type of node, i.e., eNB § PS core network optimized § No CS core network

□ New interfaces design § Simplified protocol stack § Simple, more efficient QoS § IP

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Key Features of LTE(-A)

□ Bandwidth support § Flexible component carrier from 1.4 MHz to 20 MHz § Maximum 100 MHz by aggregating 5 component carriers

□ Multiple access scheme § Downlink: OFDMA § Uplink: Single Carrier FDMA (SC-FDMA)

□ Duplex mode § FDD: Frequency division duplexing • Full-duplex and half duplex § TDD: Time division duplexing • Half duplex

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Carrier Aggregation 13 Carrier Aggregation 13 □ Carrier Aggregation (CA) Carrier Aggregation § Transmission Bandwidth can be• furtherIntra-band extended CA by means of CA • Intra-band CA § Up to 5 component carriers can be• Contiguous aggregated component for transmission carriers • Contiguous component carriers bandwidth up to 100 MHz • Non-contiguous component carriers • Non-contiguous component carriers § CA systems are deployed to improve• Inter- banddata CArates for users • Inter-band CA § Backwards compatablity is supported• Non -forcontiguous Rel. 8/9 component users carriers • Non-contiguous component carriers □ Intra-band CA § Contiguous component carriers Frequency band A Frequency band B Frequency band A Frequency band B Intra-band § Non-contiguous component carriers Intra-band Frequency band A Frequency band B

Frequency band A Frequency band B Inter-band □ Inter-band CA Frequency band A Frequency band B Inter-band § Frequency band A Frequency band B Non-contiguous component carriers MWNL Multimedia & Wireless Networking Lab. MWNL WIRELESS NETWORKING, 430.752B, 2020 SPRING Multimedia & Wireless Networking Lab. SEOUL NATIONAL UNIVERSITY UE Categories 15 UE Categories □ UE categories depending on maximum peak data rate and MIMO • UEcapabilities categories depending support on maximum peak data rate and MIMO capabilities support

Note:Note: Total numbernumber of of soft soft channel channel bits bitsfor HARQ for HARQ ≈ 8 (# of 8Independent (# of Independent HARQ process HARQ IDs) process × 3 (# ofIDs) retransmitted 3 (# of retransmitteddata) data) maximum number of bits of DL-SCH TB received× maximum within numbera TTI of bits of DL-SCH TB received within a TTI

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY Source: http://blog.3g4g.co.uk/2015/05/new-lte-ue-categories-11-12-13-and-14.html MWNL Multimedia & Wireless Networking Lab. Initial Cell Search and Selection

□ Primary Synchronization Signal (PSS) & Secondary Synchronization Signal (SSS) § Frequency and time synchronization § cell ID determination □ Master Information Block (MIB) § Transmission bandwidth and system frame number

□ System Information Block (SIB) 16 § InitialCell access Cell configuration Search and Selection

eNB

PSS SSS MIB SIB Random Access

UE

• Primary SynchronizationWIRELESS Signal NETWORKING, (PSS) 430.752B, & Secondary 2020 SPRING Synchronization Signal (SSS) SEOUL NATIONAL UNIVERSITY • Frequency and time synchronization • Physical layer cell ID determination • Master Information Block (MIB) • Transmission bandwidth and system frame number • System Information Block (SIB) • Cell access configuration MWNL Multimedia & Wireless Networking Lab. Downlink Data Transmission

□ Channel State Information (CSI) § Channel Quality Indicator (CQI), etc. □ Scheduling § Based on CQI □ HARQ ACK (or NACK) and CSI 17 Downlink Data Transmission

Data arrival eNB Scheduling

… DL control info. ACK or NACK DL data CSI CSI UE

• Channel State Information (CSI) WIRELESS NETWORKING, 430.752B, 2020 SPRING • Channel Quality IndicatorSEOUL (CQI), NATIONAL etc. UNIVERSITY

• Scheduling

• Based on CQI

• HARQ ACK (or NACK) and CSI

*HARQ: Hybrid Automatic Retransmission reQuest MWNL Multimedia & Wireless Networking Lab. Uplink Data Transmission

□ Scheduling Request (SR) □ Uplink grant □ Buffer Status Report (BSR) □ Uplink resource scheduling □ Uplink data transmission § If more uplink data arrives à piggybacking BSR 18 Uplink Data Transmission

eNB

SR UL grant BSR Scheduling UL data (BSR)

UE Data arrival (Data arrival)

• Scheduling Request (SR)

WIRELESS NETWORKING, 430.752B, 2020 SPRING • Uplink grant SEOUL NATIONAL UNIVERSITY

• Buffer Status Report (BSR)

• Uplink resource scheduling

• Uplink data transmission • If more uplink data arrives piggybacking BSR

MWNL Multimedia & Wireless Networking Lab. 22 LTE Network Architecture LTE Network Architecture

UMTSUMTS (3G) (3G) LTELTE ()(4G)

WIRELESS NETWORKING, 430.752B, 2020 SPRING MWNL SEOUL NATIONAL UNIVERSITY Multimedia & Wireless Networking Lab. Overall Architecture

□ Basic EPC architecture with E-UTRAN § User plane (data plane) 23 •OverallAII-IP packet Architecture for a UE is encapsulated and tunneled between the P-GW and eNodeB • Protocol support GTP (GPRS Tunneling Protocol) tunnel associated with each EPS bearer § Control• Basic planeEPC architecture with E-UTRAN • Control signals (channel setup, mobility support, security, etc.) between UE and MME • Signals for establishing the radio bearers and configuration

EPC (Core Network)

E-UTRAN (Access Network) Serving PDN External GW GW Network

UE eNodeB MME HSS Control Plane

User Plane

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY

MWNL Multimedia & Wireless Networking Lab. Functional LTE Network Elements

□ Evolved Node B (eNB) § Supporting LTE radio interface § Performing radio resource management

□ Entity (MME) § Managing user equipment mobility, identity and security parameters

□ Home Subscriber Server (HSS) § Managing all subscriber information of a network service provider

□ Serving Gateway (S-GW) § Routing/forwarding data packets § Mobility anchoring for 3GPP mobility

□ Packet Data Network Gateway (PDN-GW) § UE IP address allocation § Mobility anchoring for non-3GPP mobility

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY LTE to 5G (NSA and SA) (KT 5G NSA (KT and SA) netmanias.com Source:

• AMF: Access and Mobility Management Function, SMF: Session Management Function • UPF: User Plane Function, CUPS: Control and User Plane Separation

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY 26 User Plane

•UserUser plane Plane protocol architecture • E-UTRAN user plane protocol stack, shown in blue color □ • ConsistsUser plane of theprotocol Packet architecture Data Convergence Protocol (PDCP), Radio § E-UTRAN user plane protocol stack, shown in blue color Link§ Consists Control of (RLC),the Packet and Data Medium Convergence Access Protocol Control (PDCP), (MAC) Radio sublayers, Link Control which(RLC), are and terminated Medium Access in the Control eNB (MAC)on the sublayers, network which side are terminated in the eNB on the network side

LTE radio interface MWNL Multimedia & Wireless Networking Lab.

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY 27 GPRS Tunneling Protocol (GTP)

• Why is GTP used in LTE?

•GPRSIt provides Tunneling mobility Protocol (GTP)

• □MultipleWhy is GTPtunnels used can in LTE? be used by same UE to obtain different network§ It provides QoS mobility § Multiple tunnels can be used by same UE to obtain different network QoS • Main§ MainIP remains IP remains hidden so thatso thatit providesit provides security as wellsecurity as well • UE does not know the IP addresses of core network nodes • GTP tunnel example □ GTP tunnel example

IP packet GTP tunnel

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY MWNL Multimedia & Wireless Networking Lab. User Plane

□ PHY § Coding § Modulation § Antenna and resource mapping

□ MAC § MAC multiplexing § Transmission scheduling § Payload selection § Priority handling § Making a decision for modulation and resource § Hybrid ARQ

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY User Plane

□ RLC (Radio Link Control) § Transferring PDUs from higher layers (from either RRC or PDCP) § Error correction with ARQ § Concatenation/segmentation § In-sequence delivery and duplicate detection

□ PDCP (Packet Data Convergence Protocol) § Header compression and corresponding decompression § Ciphering and deciphering § Integrity protection and verification

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY 30 Control plane Control plane • Control plane protocol stack

□ Control• E-UTRAN plane user protocol plane protocolstack stack, shown in blue color § E-UTRAN control plane protocol stack, shown in blue color • Lower layers perform the same functions as those for the user § Lower layers perform the same functions as those for the user plane with planethe exception with the that exception there is thatno header there compressionis no header compression

WIRELESS NETWORKING, 430.752B, 2020 SPRING MWNL SEOUL NATIONAL UNIVERSITY Multimedia & Wireless Networking Lab. Control plane

□ RRC (Radio Resource Control) § Broadcast § Paging § RRC connection management § RB control § Mobility functions § UE measurement reporting and control

□ NAS (Non-Access Stratum) § EPS bearer management § Authentication § ECM-IDLE mobility handling § Paging origination in ECM-IDLE § Security Control * ECM: EPS Connection Management

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY 32 Downlink Flow in Link Layer Protocol Downlink Flow in Link Layer Protocol

Larmo, Anna, et al. "The LTE link-layer design," Communications Magazine, IEEE 47.4 (2009). Reference: Larmo, Anna, et al. "The LTE link-layer design." Communications Magazine, IEEE 47.4 (2009). WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY MWNL Multimedia & Wireless Networking Lab. QoS and EPS bearer

□ EPS Bearers § In order to support multiple QoS requirements, different bearers are set up within EPS

□ Minimum Guaranteed Bit Rate (GBR) bearers § Dedicated resources are allocated § By admission control function in eNB § Bit rates higher than the GBR may be allowed for a GBR bearer if resources are available § For such applications as VoIP

□ Non-GBR bearers § Used for Web browsing, FTP transfer, etc.

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY 34 QCIQCI (QoS(QoS Class Class Identifier) Identifier)

• Standardized QCIs for LTE □ Standardized QCIs for LTE

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY MWNL Multimedia & Wireless Networking Lab. QoS and EPS bearer

Check the35 book □ EstablishmentQoS and time EPS bearer for more details! § Default bearer • EstablishmentEstablished when time UE connects to PDN • Provides• Default bearer always-on connectivity and always non-GBR • Established when UE connects to PDN § Dedicated• Provides bearer always established-on connectivity laterand always non-GBR • Can• Dedicated be GBR bearer or establishednon-GBR later • Can be GBR or non-GBR □ Each •EPSEach bearerEPS bearer has has § QoS• classQoS class identifier identifier (QCI) (QCI) • Allocation and retention priority (ARP) § Allocation• Determines and retention whether a bearer priority can be (ARP) dropped if the network gets congested • Determines whether a bearer can be dropped if the network gets congested

EPS Bearer

WIRELESS NETWORKING, 430.752B, 2020 SPRING SEOUL NATIONAL UNIVERSITY MWNL Multimedia & Wireless Networking Lab.