3gpp lte(-a): part ii lte system mac/network...

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2015년 한국통신학회 이동 및 무선통신 단기강좌 3GPP LTE(-A): Part II LTE System MAC/Network Layer 2015. 8. 28. Jae-Hyun Kim [email protected] Wireless Internet aNd Network Engineering Research Lab. http://winner.ajou.ac.kr School of Electrical and Computer Engineering Ajou University, Korea

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2015년 한국통신학회 이동 및 무선통신 단기강좌

3GPP LTE(-A): Part IILTE System

MAC/Network Layer2015. 8. 28.

Jae-Hyun [email protected]

Wireless Internet aNd Network Engineering Research Lab.http://winner.ajou.ac.kr

School of Electrical and Computer Engineering Ajou University, Korea

Contents

LTE network overview• Standardization of LTE• LTE Network Architecture

User plane protocol• Packet Data Convergence Protocol• Radio Link Control• Medium Access Control

Control plane protocol• C-Plane Overview• Mobility Control• Radio Resource Management• Summary of C-Plane: Initial Attach Procedure

2

LTE network overviewStandardization of LTELTE Network Architecture

3

Release of 3GPP specifications

4

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

GSM/GPRS/EDGE enhancements

Release 99 - W-CDMA [DL:2/UL:2Mbps for 5MHz]

Release 4 – TDD [DL:2/UL:2Mbps for 5MHz]

Release 5 – HSDPA, IMS [DL:14.4Mbps/UL:2Mbps for 5MHz]

Release 6 – HSUPA, MBMS, IMS+ [DL:2/UL:5.7Mbps for 5MHz]

Release 7 – HSPA+(MIMO, HOM etc.) [DL:20/UL:10Mbps for 5MHz]

Release 8 – LTE, SAE [DL:75/UL:25Mbps for 10MHz]

Release 9 – Small LTE/SAE enhancement

Release 10 – LTE-Advanced

Release 11 Interconnection

Release 12

ITU-R M.1457IMT-2000 Recommendations

WCDMA 최초 상용화

LTE 국내 상용화

LTE 최초 상용화

WCDMA 국내 상용화

2014 2015

Release 13

LTE-A 최초 상용화

3GPP Standards

Version Released Information

Release 98 1998 This and earlier releases specify pre-3G GSM networksRelease 99 2000 Q1 Specified the first UMTS 3G networks (3.84 Mcps,W-CDMA FDD & TDD), incorporating a CDMA air interfaceRelease 4 2001 Q2 1.28 Mcps TDD (TD-SCDMA) added features including an all-IP Core NetworkRelease 5 2002 Q1 Introduced IMS and HSDPA

Release 6 2004 Q4 Integrated operation with Wireless LAN networks and adds HSUPA, MBMS, enhancements to IMS such as Push to Talk over Cellular (PoC),GAN (Generic Access Network)

Release 7 2007 Q4

Focuses on decreasing latency, improvements to QoS and real-time applications such as VoIP. This specification also focus on HSPA+(High Speed Packet Access Evolution), SIM high-speed protocol and contactless front-end interface (Near Field Communication enabling operators to deliver contactless services like Mobile Payments), EDGE Evolution. LTE & SAE Feasibility Study

Release 8 FrozenMar. 2009

LTE, All-IP Network (SAE). Release 8 constitutes a refactoring of UMTS as an entirely IP based fourth-generation network. OFDMA air interface, UMTS Femtocells, Dual carrier HSDPA

Release 9 FrozenMar. 2010

SAES Enhancements, MSR(Multi-standard radio), dual carrier HSUPA, dual band HSDPA, SON, LTE Femtocells (HeNB), LTE-A feasibility study, MBSFN, WiMaX and LTE/UMTS Interoperability,

Release 10 FrozenJune 2011

LTE Advanced fulfilling IMT Advanced 4G requirements. CoMP study, Backwards compatible with release 8 (LTE). Multi-Cell HSDPA (4 carriers).

Release 11 Frozen Mar. 2013

Advanced IP Interconnection of Services. Service layer interconnection between national operators/carriers as well as third party application providers, CoMP, eDL MIMO, eCA, MIMO OTA, HSUPA TxD & 64QAM MIMO, HSDPA 8C & MIMO, MB MSR

Release 12 FrozenMar. 2015 New carrier type, LTE-Direct, Active antenna systems, WiFi Offload and Interworking

Release 13 In progress LTE-U(Unlicensed), SDN, Virtualization & Cloud

5

3GPP Standard Documents

6

3GPP TS 36.300 overview

7

Title 3GPP TS 36.300

Scope Overview and overall description of E-UTRAN radio interface

protocol

Contentssection contents

4 Overall Architecture

5 Physical Layer계층별기능 및구조

6 Layer 2

7 RRC

8 E-UTRAN identities

주요 기능 설명

9 ARQ and HARQ

10 Mobility

11 Scheduling and Rate Control

12 DRX in RRC_CONNECTED

13 QoS

section contents

14 Security

주요 기능 설명

15 MBMS

16Radio Resource Management

aspects

17 Void

18 UE capabilities

19 S1 interface 인터페이스 별 프로토콜설명

20 X2 interface

21 Void

22Support for Self-configuration and

Self-optimization

23 Others

LTE Channel Architecture

8

PDCP: Packet Data Convergence Protocol SRB: Signalling Radio Bearer PCCH: Paging Control Channel

BCCH: Broadcast Control Channel CCCH: Common Control Channel DCCH: Dedicated Control Channel

PCH: Paging Channel BCH: Broadcast Channel RACH: Random Access Channel

DL-SCH: DownLink Shared CHannel UL-SCH: UpLink Shared Channel PBCH: Physical Broadcast Channel

PRACH: Physical Random Access Channel PDSCH: Physical Downlink Shared Channel PUSCH: Physical Uplink Shared Channel

LTE network overviewStandardization of LTELTE Network Architecture

9

Evolution of Network Architecture

10

cdma2000 Solutions Evolution :Reference Architecture for Voice Traffic

11

IP

64k PCM/32K ADPCM

PCM

BTS

ATMAAL2

ATM

Packet Pipes ATM

PCM/ Channelized T1

PSAXPSAXPSAX

MSCPSTN

Media Gateway

PSAXPSAXPSAX

MSC

BTS

ATMAAL2

ATM

Packet Pipes

PCM

Media Gateway

APX8000

Voice call Flow

64k PCM/32K ADPCM100BT

Ethernet

GX550 GX550

1

2 3

1

1 TDM

2

3

ATM :PCM 64 kbps

ATM :ADPCM 32 kbps

Tandem Tandem

4

4 IP :G.726 32 kbps

100BTEthernet

TMX880 TMX880

APX8000

RNCRNC5

5 IP :Vocoder bypass

2.5G

3G

3G+

UMTS Architecture(Release 99)

3GPP Release 1999 Network Architecture

12

RNC

RNC

BSC

SGSN

MSCVLR

Iub (ATM)

Node B

Node BPSTN

SS7

HLR

GGSN Internet

Iub (ATM)

Iu-ps (ATM)

Iu-ps (ATM)

Iu-ps (ATM)

Iu-cs (ATM)

Iu-cs (ATM)

A-interface

Gn(GTP/IP) Gi(IP)

BTS

UE

Uu

Iur (ATM)

UMTS Architecture(Release-4)

3GPP Release 4 Network Architecture

13

RNC

RNC

SGSN

MGW

Node B

Node B

PSTN

SS7

HSSHLR

GGSN Internet

IubIu-ps

Gn(GTP/IP) Gi(IP)

IurIu-cs(bearer)

MSC Server

GMSC Server

MGW

SS7 GW

SS7 GW

PCM

Iu-cs(control)

H248/IP H248/IP

RTP/IP

IP

Iub

HSS Home Subscriber Server MGW : Media Gateway

UMTS Architecture(Release-5)

14

RNC

RNC SGSN

Node B

PSTN

SS7

HSSHLR

GGSN

InternetGi(IP)

Iur

Iu

CSCF

R-SGW

PCMGn

Cx

Iub

MGWGi

CSCF

MGCFMg

T-SGW

SS7

McGrMRF

Mr

Gi

RNC : Radio Network Controller SGSN : Serving GPRS Support Node GGSN : Gateway GPRS Support Node CSCF : Call State Control Function MGCF : Media Gateway Control Function MRF : Multimedia Resource Function

SS7 : Signal System No.7 R-SGW : Roaming Signaling Gateway T-SGW : Transport Signaling Gateway

Radio Access Network (RAN)(UTRAN)

3G Core Network (CN) External Network

LTE- Evolution Path of Core Network

15

E-UTRAN(Evolved Universal Terrestrial Radio Access Network)

X2

S1

• NB : NodeB• RNC : Radio Network Controller• SGSN : Serving GPRS Support Node• GGSN : Gateway GPRS Support Node

• eNB : E-UTRAN NodeB• aGW : Access Gateway• MME : Mobility Management Entity• UPE : User Plane Entity

Overall Architectural Overview

EPS (Evolved Packet System) network elements

16

Evolved Packet Core (EPC)E-UTRAN

3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013

Interface for data planeInterface for control plane

E-SMLC: Evolved Serving Mobile Location Centre GMLC: Gateway Mobile Location Centre

HSS: Home Subscriber Server PCRF: Policy Control and Charging Rules Function

Core Network Elements

17

Network Elements Features

PCRF(Policy Control and Charging Rules Function)

Policy control decision making Controlling the flow-based charging functionalities in the PCEF (Policy Control

Enforcement Function) which resides in the P-GW• QoS authorization (QoS class identifier and bit rates)

HSS(Home Subscriber Server)

Contains users’ SAE subscription data such as EPS-subscribed QoS profile and any access restrictions for roaming

Information about the PDNs to which the user can connect Identity of the MME to which the user is currently attached or registered

E-SMLC(Evolved Serving Mobile Location Centre)

Manage the overall coordination and scheduling of resources required to find the location of a UE attached to E-UTRAN

Calculate the final location of UE based on the estimates it receives Estimate the UE speed and the achieved accuracy

GMLC (Gateway Mobile Location Centre)

Contain functionalities required to support location services Send positioning requests to the MME and receives the final location estimates

Core Network Elements

18

Network Elements Features

P-GW (PDN Gateway) IP address allocation for the UE QoS enforcement and flow-based charging according to the PCRF

S-GW (Serving Gateway)

All user IP packets are transferred through the S-GW LMA (Local Mobility Anchor) when the UE moves between eNode-Bs Retains the information about the bearers when the UE is in idle state Temporarily buffers downlink data while the MME initiates paging of the UE to

re-establish the bearers Collecting information for charging (the volume of data sent/rcvd) Mobility anchor for inter-working with GPRS and UMTS

MME(Mobility Management Entity)

Process the signaling between the UE and the CN (Core Network) (NAS: Non-Access Stratum)

Bearer & Connection management• Establishment, maintenance and release of the bearers• Establishment of the connection and security between the network and

UE

Access Network

Overall Network Architecture E-UTRAN consists of eNBs eNBs are interconnected with each other by X2 interface eNBs are connected by means of S1 interface to the EPC S1 interface supports a many-to-many relation between MMEs/S-GW

and eNBs

19 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013

S1 S1

S1 S1X2X2 S1

S1

S1 S5

S1

Access Network

The eNB hosts following functions RRM (Radio Resource Management)

Radio Bearer Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs (scheduling)

Processing user plane data IP header compression and encryption of user data stream AS security Selection of an MME at UE attachment when no routing to an MME

can be determined from the information provided by the UE Forwarding of user plane data towards S-GW

Measurement and measurement reporting configuration for mobility and scheduling

Scheduling and transmission of control messages from the MME paging messages broadcast information PWS (Public Warning System) messages

CSG (Closed Subscriber Group) handling

Transport level packet marking in the uplink (ex. Setting the DSCP (DiffServ Code Point)

20 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013

Access Network: User Plane U-Plane PDCP (Packet Data Convergence Protocol) RLC (radio Link Control)MAC (Medium Access Control) GTP (GPRS Tunneling Protocol) on the S1 (eNB↔S-GW) on the S5/S8 (S-GW ↔ P-GW)

21

• C-Plane

S5/S8a

eNB

LTE-Uu

UEApplication

IP

PDCP

L1

MAC

RLC

S1-U

PDCP

L1

MAC

RLC

GTP-U

L1

L2

UDP/IP

S-GWGTP-U

L1

L2

UDP/IP

GTP-U

L1

L2

UDP/IP

P-GW

IP

GTP-U

L1

L2

UDP/IP

SGi

Servers PDNApplication

IP

Access Network: Control Plane C-Plane Idle state Cell selection/reselection(based on radio link quality, cell status,

radio access technology), paging ,system information acquisition

Connected state RRC(radio resource control): CH quality, neighboring cell

information, mobility procedures

22

eNB

LTE-Uu

UENAS

RRC

PDCP

L1

MAC

RLC

S1-MME

PDCP

L1

MAC

RLC

SCTP

L1

L2

IP

RRC S1-AP

MMENAS

S1-AP

SCTP

L1

L2

IPAS

Interfaces

X2 and S1 user plane aspect IP packet for a UE is encapsulated and tunneled using GTP-U (GPRS Tunneling

Protocol – User Plane) Local transport protocol is UDP

• No flow control, No error control

X2 and S1 control plane aspect S1AP (S1 Application Protocol) is used to transport the signaling message

between eNode-B and the MME Local transport protocol is SCTP

• Guarantees delivery of signaling messages• Support multiple SAE bearers

23

User plane for S1-U interface Control plane for S1-MME Interface

3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013

SCTP : Stream Control Transmission Protocol

EPS Bearer Service Architecture

EPS bearer / E-RAB is established when the UE connects to a PDN Default bearer remains established throughout the lifetime of the PDN connection

Dedicated bearer Any additional EPS bearer/E-RAB that is established to the same

PDN is referred to as a dedicated bearer.

24

P-GWS-GW PeerEntity

UE eNB

EPS Bearer

Radio Bearer S1 Bearer

End-to-end Service

External Bearer

Radio S5/S8

Internet

S1

E-UTRAN EPC

Gi

E-RAB S5/S8 Bearer

3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013

QoS and EPS Bearers

Multiple applications have different QoSrequirements Different bearers are set up within EPS each being associated with a QoS

GBR bearers Permanent allocation of dedicated transmission resources ex) VoIP

Non-GBR bearers Do not guarantee any particular bit rate ex) web browsing, FTP transfer

Each bearer has an associated QCI, and an ARP Priority and packet delay budget RLC mode, scheduling policy, queue management and rate shaping policy

25GBR : Minimum Guaranteed Bit Rate QCI: QoS Class Identifier ARP: Allocation and Retention Priority

Standardized QCI for LTE

QCI(QoS Class Identifier)

ResourceType

Priority

PacketDelay

Budget

PacketError Loss

RateExample Services

1

GBR

2 100ms 10-2 Conversational Voice

2 4 150ms 10-3 Conversational Video (Live Streaming)

3 3 50ms 10-3 Real Time Gaming

4 5 300ms 10-6 Non-Conversational Video (Buffered Streaming)

5

Non-GBR

1 100ms 10-6 IMS Signaling

6 6 300ms 10-6Video (Buffered Streaming),TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing,

progressive video, etc.)

7 7 100ms 10-3 Voice, Video (Live Streaming)Interactive Gaming

8 8300ms 10-6

Video (Buffered Streaming),TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing,

progressive video, etc.)9 9

26 3GPP TS 23.203 v12.1.0, “Policy and charging control architecture,” Jun. 2013.

User Plane ProtocolPacket Data Convergence ProtocolRadio Link ControlMedium Access Control

27

Overview of User Plane Protocol

PDCP layer Process RRC messages in the control plane and IP

messages in the user plane Header compression Security reordering and retransmission during handover

RLC layer Segmentation and reassembly ARQ Reordering for HARQ

MAC layer Multiplexing of data from different radio bearer Achieve QoS for each radio bearer Report the eNodeB to the buffer size for uplink

28

PDCP : Packet Data Convergence Protocol RLC: Radio Link Control MAC: Medium Access Control HARQ : Hybrid Automatic Repeat RequestQoS : Quality of Service

S5/S8a

eNB

LTE-Uu

UEApplication

IP

PDCP

L1

MAC

RLC

S1-U

PDCP

L1

MAC

RLC

GTP-U

L1

L2

UDP/IP

S-GWGTP-U

L1

L2

UDP/IP

GTP-U

L1

L2

UDP/IP

P-GW

IP

GTP-U

L1

L2

UDP/IP

SGi

Servers PDNApplication

IP

PDCP overview

Functions Header compression/

decompression of user plane data

Security Ciphering and deciphering for

user plane and control plane data Integrity protection and

verification for control plane data

Handover support In-sequence delivery and

reordering of upper layer PDUs at handover

Lossless handover for user plane data mapped on RLC Acknowledge Mode (AM)

Discard for timeout user plane data

29

* 3GPP TS 36.323 v11.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification”(Release 11), April, 2013

Header Compression

Robust Header Compression (ROHC) Introduced RFC 3095 and RFC 4815 Increase channel efficiency by reducing overhead Robust at unreliable link Three different mode : Unidirectional mode(U-mode), Bidirectional

Optimistic mode(O-mode), and Bidirectional Reliable mode(R-mode) Compression example VoIP (in the active period)

• payload 5,11~32 bytes ([email protected]~12.2kbps)+ header 40/60 bytes (RTP 12+UDP 8+IPv4 20/IPv6 40) payload 32 bytes + header 4~6 bytes

30 acticom mobile networks, http://www.acticom.de/en/

Wireless Link

Payload RTP UDP IP

CompressorDe-Compressor

Framing/Error Detection

RoHC Context

Payload H

CompressedHeader

RoHC Context

PayloadIP RTP UDP

CompressorDe-Compressor

Framing/Error Detection

Sender Receiver

Header Compression

Header Fields Classification

31

Type DescriptionInferred” They are never sent and they can

be known by other component in the header

Static* Send only once, their valuesnever change during the stream

Static-def**

Send only once, they give the definition of the stream

Static-known^

They are never sent and their values are known

Changing< Header fields with a changing value. The change can be periodic or randomly. They are always send

Ver*

ToS< Flow ID**Length” Next

Header* Hop Limit<

Source Address**

Destination Address**

Source Port** Destination Port**Length” Checksum<

Ver^ P* E* CCnt< M< P.Type< Sequence Number<

Timestamp<

Source Synchronization Indentification(SSRC)**

Source Contribution Identification (1st)<

Contributing source (CSRC)<

Source Contribution Identification (last)<

Application Data

0 15 31

IPv6

UDP

RTP

Header Compression

Header Fields Classification

32

Type DescriptionInferred” They are never sent and they can

be known by other component in the header

Static* Send only once, their valuesnever change during the stream

Static-def**

Send only once, they give the definition of the stream

Static-known^

They are never sent and their values are known

Changing< Header fields with a changing value. The change can be periodic or randomly. They are always send

Static Info

ROHC header

Application Data

1 byte

3~5 bytes

Header Compression

ROHC compression with U,O,R operation mode

33

Security

LTE security distribution NAS security Carried out for NAS messages / between UE and MME NAS messages are integrity protected and ciphered with extra NAS

security header

AS security (PDCP) Carried out for RRC and user plane data / between UE and eNB RRC messages are integrity protected and ciphered U-plane data is only ciphered

34 3GLTEINFO, http://www.3glteinfo.com/lte-security-architecture-20110325/

Security

Ciphering Prevent unauthorized user from seeing the content of

communication For control plane (RRC) data and user plane data PDCP Control PDUs (ROHC feedback and PDCP status reports)

are not ciphered

Integrity protection Used to detect whether a text is tampered during delivery Control plane (RRC) data For RN, User plane data 32-bit Message Authentication Code for Integrity (MAC-I)

35

PDCP PDU format

PDCP Data PDU User plane PDCP Data PDU Long PDCP SN (12bits) (DRBs mapped on RLC AM or UM) Short PDCP SN (7bits) (DRBs mapped on RLC UM) Integrity protection for RN user plane (DRBs mapped on RLC AM or

RLC UM) Extended PDCP SN (15 bits) (DRBs mapped on RLC AM)

Control plane PDCP Data PDU For control plane SRBs

PDCP Control PDU Interspersed ROHC feedback packet DRBs mapped on RLC AM or RLC UM

Status report DRBs mapped on RLC AM

36

D/C SN or Type MAC-IData(DRB) O SN (7,12, 15 bits) Δ

Data(SRB) X SN (5 bits) O

ROHC feedback O Type X

StatusReport O Type X

* 3GPP TS 36.323 v11.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification”(Release 11), April, 2013

PDCP PDU format

PDCP Data PDU

37

<User plane PDCP Data PDU with long PDCP SN (12 bits)>

<User plane PDCP Data PDU with short PDCP SN (7 bits)>

<User plane PDCP Data PDU with extended PDCP SN (15 bits)>

<RN user plane PDCP Data PDU with integrity protection><Control plane PDCP Data PDU for SRBs>

* 3GPP TS 36.323 v11.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification”(Release 11), April, 2013

PDCP PDU format

PDCP Control PDU

38

* 3GPP TS 36.323 v11.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification”(Release 11), April, 2013

<PDCP Control PDU for interspersed ROHC feedback packet>

<PDCP Control PDU for PDCP status report using a 12 bit SN>

<PDCP Control PDU for PDCP status report using a 15 bit SN>• FMS: PDCP SN of the first missing PDCP SDU

User Plane ProtocolPacket Data Convergence ProtocolRadio Link ControlMedium Access Control

39

RLC Overview

Radio Link Control(RLC) Located between RRC/PDCP and MAC Error correction through ARQ Segmentation/Concatenation/Reassembly of RLC SDUs 3 transfer modes TM (Transfer Mode)

• Only used for RRC messages which do not need RLC configuration• through BCCH, DL/UL CCCH and PCCH

UM (Unacknowledged Mode)• Utilized by delay-sensitive and error-tolerant real-time applications• through DL/UL DTCH, MCCH or MTCH

AM (Acknowledged Mode)• Utilized by error-sensitive and delay-tolerant non-real-time applications• through DL/UL DCCH or DL/UL DTCH

40

SDU: Service Data Unit BCCH: Broadcast Control Channel CCCH: Common Control ChannelPCCH: Paging Control Channel DTCH: Dedicated Traffic Channel MCCH: Multicast Control ChannelMTCH: Multicast Traffic Channel DCCH: Dedicated Control Channel

TM RLC entity

Features No segmentation/ No concatenation No RLC headers Deliver TMD PDUs Only for RRC messages which do not need RLC configuration

SI messages Paging messages RRC messages which are sent when no SRBs other than SRB0

41

< Model of TM RLC entity >BCCH : Broadcast Control Channel PCCH : Paging Control Channel SRB: Signaling Radio BearerCCCH : Common Control Channel SI: System Information TMD: Transparent Mode Data

UM RLC entity

Features Segment or concatenate RLC SDUs Add or remove RLC headers Reorder received RLC PDUs Reassembly of RLC SDUs Used by delay-sensitive and error-tolerant real-time applications VoIP, MBMS

42DTCH : Dedicated Traffic Channel MCCH : Multicast Control Channel SDU: Service Data UnitMTCH : Multicast Traffic Channel MBMS: Multimedia Broadcast/Multicast ServiceUMD: Unacknowledged Mode Data

< Model of UM RLC entity >

concatenation

UM data transfer

43< Example of PDU loss detection with HARQ reordering >

AM RLC entity

Features Similar function of UM RLC entity Support ARQ (Stop and Wait) Detect the loss of AMD PDU and request retransmission to peer Deliver AMD PDU, AMD PDU segment and STATUS PDU Used by error-sensitive and delay-tolerant non-real-time applications

Interactive/background type services: Web-browsing, file downloading

44

< Model of AM RLC entity >

ARQ: Automatic Repeat reQuest

AM data transfer

Retransmission and resegmentation Status reports from receiving side ACK/NACK

RLC data PDU is stored in retransmission buffer Resegment the original RLC PDU into smaller PDU segments

45< Example of RLC re-segmentation >

Data flow through L2 protocol stack

46A. Larmo et al., "The LTE link-layer design," Communications Magazine, IEEE , April 2009.

User Plane ProtocolPacket Data Convergence ProtocolRadio Link ControlMedium Access Control

47

MAC overview

48

Transport channel name Direction AcronymBroadcast Channel Downlink BCHDownlink Shared Channel Downlink DL-SCHPaging Channel Downlink PCHMulticast Channel Downlink MCHUplink Shared Channel Uplink UL-SCHRandom Access Channel Uplink RACH

Logical channel name Type AcronymBroadcast Control Channel Control BCCHPaging Control Channel Control PCCHCommon Control Channel Control CCCHDedicated Control Channel Control DCCHMulticast Control Channel Control MCCHDedicated Traffic Channel Traffic DTCHMulticast Traffic Channel Traffic MTCH

Functions Channel Mapping Building MAC PDU Random access Scheduling Power saving by Discontinuous

Reception(DRX) Error correction through HARQ Multiplexing / Demultiplexing Transport Format Selection Priority handling Logical Channel prioritization

• 3GPP TS 36.300 V11.5.0, "E-UTRA and E-UTRAN; Overall description; Stage 2(Release 11)", Mar, 2013.• 3GPP TS 36.300 V11.6.0, “E-UTRA and E-UTRAN; Overall description”, June, 2013.

Building MAC PDU(MAC PDU Format)

MAC PDU = MAC Header + MAC Payload MAC subheader Logical Channel ID (LCID), Length(L) field

MAC control element Used for MAC-level peer-to-peer signaling

Buffer status report / UE’s available power headroom in uplink/ DRX command, etc.

Headerless MAC PDU MAC PDU constructed without header Use it when MAC PDU is used to transport data from the PCCH or BCCH

PCCH or BCCH : one-to-one corresponding between MAC SDU and MAC PDU

49

Random Access(RA) Procedure

Purpose RA is performed when UE didn’t assigned resource for data transmission

Contention based Perform when eNB doesn’t know the presence of UE or UE have data to transmit

while UE lost timing information Examples

• Initial access from RRC_IDLE• RRC Connection Re-establishment procedure• UL data arrival during RRC_CONNECTED requiring random access procedure

» E.g. when UL synchronisation status is "non-synchronised" or there are no PUCCH resources for SR available

Non-contention based Perform when eNB know the incoming of UE or eNB have data to transmit while

UE lost timing information Examples

• Handover• For positioning purpose during RRC_CONNECTED requiring RA• DL data arrival during RRC_CONNECTED requiring random access procedure

» E.g. when UL synchronisation status is “non-synchronised”

50

Random Access Procedure- Contention based(1)

51

(0) Selection of preamble : select a preamble in preamble groups

Preambles for contention based access(2 groups, select a group by message size)

Total 64 preambles(spreading codes) in each cell

Preambles forcontention-free access

(1) Preamble Transmission on RACH• Set transmission power : according to DL estimation on RSRP• Power ramping : increase transmission power by number of retrials

(2) RA Response (PDCCH tagged with RA-RNTI + PDSCH)• Send response for a UE if single preamble is detected• This message includes UL resource grant, timing alignment

information for sending third message• Assign a temporary ID for UE(TC-RNTI)

• RSRP : Reference Signal Received Power• RA-RNTI : Random Access Radio Network Temporary Identifier

•TC-RNTI : Temporary Cell Radio Network Temporary Identifier

• No RA Response for UE Backoff Back to Selection of preamble

Random Access Procedure- Contention based(2)

52

(3) First PUSCH TX – Includes TC/C-RNTI

• Conveys actual random access procedure message• If multiple UEs selected same RACH and preamble in (1), collision occurs• No collision eNB detects one C-RNTI and get message from PUSCH

• UE considers as success, and TC-RNTI is promoted to C-RNTI• If (3) is collided No arrival of Contention Resolution for UE Backoff Back to Selection of preamble

(4) Contention Resolution on DL

Random Access Procedure- Non-Contention based

53

(0) RA Preamble Assignment

(1) RA Preamble

(2) RA Response

• eNB assigns to UE a non-contention Random Access Preamble before RA(ex> before handover)

• Transmits non-contention RA Preamble

• Conveys at least timing alignment information and initial UL grant for handover, timing alignment information for DL data arrival, RA-preamble identifier

Data Transmission after RA- Downlink Scheduling(1) Dynamic Scheduling Signal and transmit data without periodicity Signaling is required at each transmission

54

Signaling for dynamic scheduled data

PDCCH

DL-SCH

•PDCCH(Physical Downlink Control Channel)•DL-SCH(Downlink Shared Channel)

Data Transmission after RA- Downlink Scheduling(2) Semi-persistent scheduling Schedule periodical transmission Only the one signaling at first transmission is required Reduce signaling overhead

Scheduling periodicity is configured by RRC

55

PDCCH

DL-SCH

Signaling for semi-persistent data(example : period = 4)

No additional signalling for semi-persistent scheduled data

Data Transmission after RA- Uplink Scheduling Procedure eNodeB notifies the TX slot which can be used by UE for uplink transmission UE sends data through UL-SCH and activates HARQ process

HARQ mechanism : Stop-and-Wait

eNodeB signals transmission result by HARQ ACK/NACK to UE For NACK, eNodeB schedule for retransmission through PDCCH

56

Tx in 5

Txin 7

Tx in 7

ULData

PDCCH

UL-SCH

ACK NACKPHICH

1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6

ULData

7

ULData

N=4 N=4UE Response eNB Response

Subframe

• Example for N=4 : UE/eNB response after 4 subframe

•PDCCH(Physical Downlink Control Channel)•UL-SCH(Uplink Shared Channel)•PHICH(Physical HARQ Indicator Channel)

Wireless Packet Scheduling Algorithm

Features of Scheduling Algorithms for Wireless Network Each user experience different transmission speed Channel environment differ by randomly through time Bursty error occurs User’s channel capacity changes by fading Require to estimate channel environment

57

• Additional Slides

Signaling for Resource Allocation

For resource allocation, eNodeB requires… Channel Quality Information(frequency specific) Traffic information(volume and priority, queue

status

Signaling tradeoff Data rate ↔ Overhead

CQI measurement DL : through the feedback of CQIs by UEs UL : by Sounding Reference Signals(SRS) transmitted by

UE to estimate ch. quality Frequency of the CQI reports is configurable

Reduce overhead ↔ Accuracy

Information about queue status DL : directly available at eNB UL : specific reporting mechanism

58

• Additional Slides

Scheduling Algorithms

Opportunistic algorithm / High Rate User First (HRUF) Simplest algorithm considering wireless channel Optimizing the total throughput Assign resources to user with best CQI

Fairness problem occurs If the an user with best channel continuously generates traffic, then other

users cannot be assigned wireless resource Other users cannot transmit their traffic Fairness and QoS are not

assured

59

max ( )i t

( )i t : Maximum transmission rate of user i

• Additional Slides

Scheduling Algorithms

Fair algorithmsMinimize UE latency Ex. Min-Max : Maximizes the minimum allocated rate

Total Throughput reduced

60

max min{ ( )}iit

• Additional Slides

Scheduling Algorithms

Proportional Fair Share Scheduling (PFSS) AlgorithmMaximize Throughput with some degree of fairness Algorithm Basically, schedule UE when its instantaneous channel quality is

high relative to its own average channel Reduce priority of UE by volume of received traffic increase

fairness

61

( )max

ˆ ( )i

i

tt

1 ( -1)( ) 1- ( -1)e e

served rate in slot tt tT T

Te : Estimation interval

m : resource block

f : subframe

2( ) log 1 ( , )i kt SNR m f

Large Te tends to maximize the total average throughputSmall Te tends to maximize fairness

• Additional Slides

Retransmission – HARQ (1/5)

Downlink : Asynchronous adaptive HARQ Asynchronous Retransmission with additional explicit signaling to indicate the HARQ

process number to the receiver

Adaptive HARQ Modulation and coding scheme(MCS), resource allocation can be

changed Non-adaptive HARQ : retransmit with previous MCS and resource

62

Retransmission – HARQ (2/5)

Uplink : Synchronous Non-adaptive/adaptive HARQ Uplink : Synchronous HARQ Synchronous

• Retransmission occur at predefined times relative to the initial transmission to reduce control signaling

63

Grant

Data

PDCCH

UL-SCH

Grant

New/ReTxData

PHICH ACK /NACK

HARQfeedback seen

by the UE

PDCCHseen by the UE

UE behaviour

ACK or NACK

NewTransmission

New transmission accordingto PDCCH

ACKor NACK

Retrans-mission

Retransmission according toPDCCH(adaptive retransmission)

ACK NoneNo (re)transmissionPDCCH is required to resumeRetransmissions

NACK None Non-adaptive retransmission

Power Saving/Fast Wake-up –Discontinuous Reception(DRX)

64

Power saving in UMTS Through the state change from CELL_DCH to IDLE_MODE Fast recovering to CELL_DCH takes undesired delay

•DCH (Dedicated Channel)•FACH (Forward access channel)•PCH (Cell Paging channel)•URA_PCH (URA Paging channel).

Power Saving/Fast Wake-up –Discontinuous Reception(DRX)

65

RRC_CONNECTED

RRC_IDLE

• DRX UE only listens at certain Intervals• DRX reduced battery consumption• DRX resume transfer even quicker• DRX reduced signaling

Power Saving in LTE/LTE-Advanced : Discontinuous Reception(DRX) Power saving with maintaining connected states When need power saving Change to DRX mode while maintain RRC_CONNECTED state UE can fast wake-up, because it maintain connectivity with eNodeB

Power Saving/Fast Wake-up –Discontinuous Reception (DRX) UE does not monitor the downlink channels during

such DRX period HARQ Round Trip Time (RTT) Short cycle, Long cycle Wake-up and check downlink during “on duration” only By two timer, control wake-up interval(=short DRX cycle and long

DRX cycle)

66

ActivateInactivity timer

ActivateShort DRX Cycle Timer

② ⑤

⑥ enter short DRX mode enter long DRX mode

Control Plane ProtocolC-Plane OverviewMobility ControlRadio Resource ManagementSummary of C-Plane: Initial Attach Procedure

67

Control Plane Protocol Overview

Non-access stratum PLMN selection Tracking area update Paging Authentication EPS bearer establishment,

modification and release

Access stratum control plane radio-specific functionalities The AS interacts

with the NAS (upper layers)

68RRC: Radio Resource Control PDCP: Packet Data Convergence ProtocolRLC: Radio Link Control PLMN: Public Land Mobile Network EPS: Evolved Packet System

eNB

PHY

UE

PHY

MAC

RLC

MAC

MME

RLC

NAS NAS

RRC RRC

PDCP PDCP

PHY

MAC

IP

S1-AP

SCTP

PHY

MAC

IP

S1-AP

SCTP

LTE-Uu(radio interface)

S1-MME(logical interface)

Control Plane Protocol Overview: NAS Overview Highest stratum of c-plane (UE <-> MME) S1-MME (eNB – MME)

Main functions EPS mobility management UE mobility

EPS session management IP connectivity between the UE and a P-GW

Security integrity protection and ciphering of NAS signaling messages.

69 3GPP TS 24.301 V10.7.0 “UMTS; LTE; NAS; EPS; Stage 3”, July, 2012 3GPP TS 24.401 V8.9.0 “ LTE; GPRS enhancements for E-UTRAN access”, March, 2010

Control Plane Protocol Overview: RRC Overview AS of c-plane (UE <-> eNB) LTE-Uu interface

Main functions Broadcast SI related to NAS and AS Paging Establishment of an RRC connection (UE<->E-UTRAN) Security functions (key management) Establishment of p-to-p Radio BearersMobility functions QoS management functions UE measurement reporting NAS direct message transfer (NAS<->UE)

70 3GPP, "TS 36.331 V10.5.0 Radio Resource Control (RRC) Protocol specification (Release 10)," ed, 2012.

NAS/RRC State

Protocol State Description

NAS(UE,MME)

EMM-Deregistered • UE is detached• No EMM context has been established in UE and MME.

EMM-Registered • UE has been attached• IP has been assigned• An EMM Context has been established • A default EPS Bearer has been activated• The MME knows the location of the UE(TA).

ECM-Idle • No NAS signaling connection (ECM connection)• No UE context held in E-UTRAN(eNB)• The MME knows the location of the UE(TA)

ECM-Connected • NAS signaling connection (ECM connection; a RRC connection & a S1 signaling connection)

• The MME knows the location of the UE(cell)

RRC(UE,eNB)

RRC-Idle • RRC connection has not been established.RRC-Connected • RRC connection has been established.

71TA: Tracking Area EMM: EPS Mobility Management ECM: EPS Connection ManagementMME: Mobility Management Entity1. Netmanias, “EMM and ECM States,” http://www.netmanias.com, 2013.

NAS/RRC State

72

When UE is switched on for the first time after subscription

When UE is switched on after a long time after the power has been turned off

There exists no UE context in the UE and MME.

NAS/RRC State

73

When UE is switched on within a certain period of time after the power has been turned off

When ECM connection is released during communication due to radio link failure

Some UE context can still be stored in the UE and MME (e.g., to avoid running an AKA procedure during every attach procedure).

NAS/RRC State

74

When UE is attached to the network (MME) and using services

The mobility of UE is handled by handover

NAS/RRC State

75

NAS/RRC State

76

When UE is attached to the network (MME) and not using any service

NAS/RRC State

77

Control Plane Protocol Overview: RRC States

RRC_IDLE UE known in EPC and has IP

address UE location known on Tracking

Area level Paging in TA controlled by EPC UE-based cell-selection and TA

update

RRC_CONNECTED UE known in EPC and E-

UTRAN/eNB UE location known on cell level Unicast data transfer is possible eNB-based mobility DRX supported for power

saving

78

2.

3.

5.HO

Control Plane Protocol Overview: UE Operation in RRC States

RRC_IDLEMonitors a paging channel incoming calls system information change ETWS, CMAS

measurement cell (re-)selection Acquire system information

(MIB, SIBs)

RRC_CONNECTEDMonitors a Paging channel

and/or SIB1 detect system information change

Monitor control channelsassociated and data channel

Provide channel quality and feedback information

measurement and reportingAcquire system information

79DRX: Discontinuous Reception ETWS: Earthquake and Tsunami Warning SystemCMAS: Commercial Mobile Alert Service

Control Plane Protocol Overview: UE Camping Procedure

80 Bong Youl (Vrian) Cho, “LTE RRC/RRM”, TTA LTE/MIMO Standards/Technology Trainning, May 2012

AS

PHY

RRC

NAS

(2) TriggerSystemAcquisition

(4) ScheduleBroadcast ControlChannel read

(6) Process SIB1Check PLMNIs Cell reserved?Is CSG Id valid?Cell belong to Forbidden TA?Cell barred?If fail, go back to (3)If ok, go to (7)

(8) All SIBsobtained

(10) Service Obtained(Camped)

(1) PLMN selectionRead USIMRead stored info on MESelect Band, PLMN, etc

(3) AcquisitionScan Band/Freq

(5) Read MIB/SIB1Using SI-RNTI

(7) SIB2 and Other SIBs(9) Cell isSelected and UE camps

RRC Services

Services provided to upper layers Broadcast of common control information Notification of UEs in RRC_IDLE receiving call, ETWS, CMAS

Transfer of dedicated control information information for one specific UE

Services expected from lower layers PDCP Integrity protection and ciphering

RLC Reliable and in-sequence transfer of information

• without introducing duplicates• with support for segmentation and concatenation

81ETWS: Earthquake and Tsunami Warning System CMAS: Commercial Mobile Alert Service

RRC Functions

82

Broadcast of system information

NAS common information For UEs in RRC_IDLE

• Cell (re-)selection parameters• Neighboring cell information

For UEs in RRC_CONNECTED• Common channel configuration information

RRC connection control

Paging Establishment/modification/release of RRC connection or DRBs Initial security activation RRC connection mobility Radio configuration control (ARQ, HARQ, DRX) QoS control Recovery from radio link failure

Inter-RAT mobility Security activation Transfer of RRC context information

Measurement configuration control and reporting

Establishment/modification/release of measurements Setup and release of measurement gaps Measurement reporting

Transfer of information Dedicated NAS information Non-3GPP dedicated information UE radio access capability information

Others Generic protocol error handling Support of self-configuration and self-optimization

Connection Control

Security activation Ciphering of both control plane RRC data (SRBs 1 and 2) and

user plane data (all DRBs) Integrity protection which is used for control plane data only

Connection establishment, modification and release DRB establishment, modification and release

83SRB: Signaling Radio Bearers DRB: Date Radio Bearers

Connection Establishment and Release

84

Data

DRB Establishment: Signaling Radio Bearers SRB: radio bearers that are used only for the

transmission of RRC and NAS messages SRB0 For RRC messages Using the CCCH logical channel

SRB1 For RRC messages (which may include a piggybacked NAS message) For NAS messages prior to establishment of SRB2 All using DCCH logical channel

SRB2 For NAS messages Using DCCH logical channel Lower-priority than SRB1 Always configured by E-UTRAN after security activation

85CCCH: Common Control Channel DCCH: Dedicated Control Channel

DRB Establishment : Signaling Radio Bearers

86

An EPS bearer is mapped (1-to-1) to a DRB A DRB is mapped (1-to-1) to a DTCH logical channel All logical channels are mapped (n-to-1) to the DL-SCH

or UL-SCH DL-SCH or UL-SCH are mapped (1-to-1) to the

corresponding PDSCH or PUSCH

Break Time!-Carrier Aggregation-WiFi Interworking

87

Multi-Carrier VS. Carrier Aggregation

88

광대역 LTE VS. Carrier Aggregation

89

800MHz

900MHz

1.8GHz

2.1GHz

2.3GHz

2.6GHz

KT파워텔

KTKT4GLTE

SKT2G

CDMA

SKT4GLTE

LG U+4GLTE

KT파워텔

KTKT4GLTE

SKT2G

CDMA

SKT4GLTE

LG U+4GLTE

811 816 817 819 824 829 839 849 856 861 862 864 869 874 884 894

KT4GLTE

905 915 950

KT4GLTE

960

1735 1740 1745 1755173017251715

LG U+2.5G

CDMARev.A

1765 1770 1780 1840 186018301810

LG U+2.5G

CDMARev.A

18701850

KT3G

WCDMA

1960 198019301920

LG U+4GLTE

21702110 2150

SKT3G

WCDMA

LG U+4GLTE

2120

KT3G

WCDMA

SKT3G

WCDMA

2331.5 2358.523272300

SKT4G

WiBro

KT4G

WiBro

25402520 26602640

Uplink Downlink

800MHz

900MHz

1.8GHz

2.1GHz

2.3GHz

2.6GHz

KT파워텔

KTKT4GLTE

SKT2G

CDMA

SKT4GLTE

LG U+4GLTE

KT파워텔

KTKT4GLTE

SKT2G

CDMA

SKT4GLTE

LG U+4GLTE

811 816 817 819 824 829 839 849 856 861 862 864 869 874 884 894

KT4GLTE

905 915 950

KT4GLTE

960

KT4GLTE

1735

KT4GLTE

1740 1745 1755

SKT4GLTE

SKT4GLTE

173017251715

LG U+2.5G

CDMARev.A

1765 1770 1780

2013.8.30 주파수 경매결과

KT4GLTE

KT4GLTE

1840 1860

SKT4GLTE

18301810

LG U+2.5G

CDMARev.A

18701850

KT3G

WCDMA

1960 198019301920

LG U+4GLTE

21702110 2150

SKT3G

WCDMA

LG U+4GLTE

2120

KT3G

WCDMA

SKT3G

WCDMA

2331.5 2358.523272300

SKT4G

WiBro

KT4G

WiBro

25402520

LG U+4GLTE

26602640

LG U+4GLTE

Uplink Downlink

2세대 3세대 3.9세대

KT4GLTE

KT4GLTE

국내 주파수 활용 현황

4세대`12.8 4세대`13.7

SKT4GLTE

SKT4GLTE

SKT: 25+30MHz, KT: 25(30)+30(35)MHz, LGU+: 40+40MHz

Status of Commercial Services for CA

Commercial services for Multi-carrier(MC) and CA * SKT

LTE-A network deployment for 850Mhz & 1.8GHz frequency band• Deployment completion in 84 major cities, Korea (2013. 07)• Starting MC service (2012.07)• Starting CA service (2013.06)• Starting Broadband LTE (2013.08)• Starting Broadband LTE-A (Broadband LTE + CA) (2014.06.19)

LG U+ LTE-A network deployment for 800Mhz & 2.1GHz & 2.6GHz frequency bands

• Deployment completion in Seoul and major cities, Korea (3Q of 2013)• Deployment completion in rest cities, Korea (4Q of 2013)• Starting MC service (2013.05)• Starting CA service (2013.07)• Starting Broadband LTE (2013.08)• Starting Broadband LTE-A (Broadband LTE + CA) (2014.06.21)

KT LTE-A network deployment for 900Mhz & 1.8GHz frequency band

• Deployment completion in Seoul and major cities, Korea (3Q of 2013)• Deployment completion in rest cities, Korea (4Q of 2013)• Starting Broadband LTE (2013.09)• Starting Broadband LTE-A (Broadband LTE + CA) (2014.07.01)

91 SKT hompage, “SK텔레콤, 30일 84개시중심가로 ‘LTE-A’ 확대”, http://www.sktelecom.com, July, 2013. LGU+ homepage, “LG유플러스, 세계최초 ‘100% LTE’ 상용화”, www.uplus.co.kr, July, 2013.

Status of Commercial Services for CA

SKT: “세계 최초 광대역 LTE-A 서비스” 세계최초 X3 Carrier Aggregation 상용화 서비스 (14년 6월)광대역 LTE-A: 광대역 LTE+ CA (DL bandwidth: 20MHz +10MHz)

92

Status of Commercial Services for CA

LGU+: “8ollow Me!” 3사중 최대 LTE 주파수 확보 (총 80MHz) (13년 7월) 2015년 3 band CA 서비스 예정

93

Service mode

*123456# 으로 진입 EARFCN (E-UTRA Absolute Radio

Frequency Channel Number) 현재 잡고 있는 주파수의 번호

• Band 5: 800MHz 2500/20500• Band 3 광대역: 1.8GHz 1350/19350

Band Band 5: LGU+, 850 MHz Band 1: LGU+ 2100 MHz Band 7: LGU+ 2600 MHz Band 8: KT, 900 MHz Band 3: KT, 1800 MHz Band 5: SK, 850 MHz Band 3: SK, 1800 MHz

94

Service mode

PLMN (public land mobile network) 이동통신사 고유번호

• SK: 45005, KT: 48008, LGU+:45006• 해외로밍시 계약사업자망에 접속

TAC(Tracking area code) 페이징 단위

PCI (Physical cell ID) 504개 eNB ID 할당

RSRP, RSRQ, RSSI 신호세기

RRC (Radio Resource Control) IDLE/Connected

CQI Modulation 상태

95

Service mode

SVC: CS_PS Circuit/Packet switching 모두사용

TMSI (Temporary Mobile Subscriber Identity) eNB가 UE에게 부여하는 식별 번호

ANT 안테나수

CA (Carrier Aggregation)

96

WiFi Interworking

KT: “LTE와 WiFi를 묶어 데이터통신 서비스 제공” 데이터통화 속도 최대 1.17Gbps 제공 (2015년 6월)

97

Control Plane ProtocolC-Plane OverviewMobility ControlRadio Resource ManagementSummary of C-Plane: Initial Attach Procedure

98

Mobility Control

Criteria for cell selection or reselection Radio link quality: primary criterion UE capability Subscriber type Cell type

E-UTRAN provides a list of neighboring frequencies and cells; white-list or black-list

99

Mobility in RRC_IDLE: PLMN and Cell Selection PLMN selection The NAS handles PLMN selection based on a list of available PLMNs

provided by the AS

Cell selection (EMM-DEREGISTERED) The UE searching for the strongest cell on all supported carrier

frequencies of each supported RAT Using NAS’s support and stored information from a previous access Requirement: not take too long

Cell reselection (EMM-REGISTERED) Move the UE to the best cell of the selected PLMN

100

Mobility in RRC_IDLE: Cell Reselection

101

RRC_IDLE Mobility

Measurement and evaluation of serving cell

Measurement of neighbour cells

Evaluation of neighbour cells for cell reselection

Acquisition of the system information of the target cell

Cell reselection to the target cell

Mobility in RRC_IDLE: Cell Selection Criteria

102

Cell selection: received level & qualitySrxlev &Squal

Srxlev rxlevmeas rxlevmin rxlevminoffsetSqual qualmeas qualmin qualminoffset

rxlevmeas: Measured cell RX level value (RSRP)

qualmeas: Measured cell quality value (RSRQ)

rxlevmin: Minimum required RX level in the cell (dBm), in SIB1

qualmin: Minimum required quality level in the cell (dB), in SIB1

rxlevminoffset, qualminoffset: offsets which may be configured to

prevent ping-pong between PLMNs, in SIB1

Mobility in RRC_CONNECTED

103

Mobility in RRC_CONNECTED: Handover

UE

Measurement Report

RRCConnectionReconfiguration

Handover Preparation

Source eNB Target eNB

Random access procedure

RRCConnectionReconfigurationComplete

UE RRC context information(UE capabilities, current AS-

configuration, UE-specific RRM information

Handover command

information for random access(mobility control, radio resource configuration), dedicated radio resource security configuration, C-RNTI

104

Mobility in RRC_CONNECTED: Handover Handover from Macro cell to macro cell HO triggering condition UE satisfies A3 condition during TTT

-> HO request to S-eNB -> HO execution

105

• A3 satisfaction

• H/O completion

• HO execution

TTT HO delay

Hyst + offset

Mobility in RRC_CONNECTED : Seamless Handover Seamless handover OBJECTIVE : Interruption Time Minimization Used for all RBs carrying control plane data and user plane data

mapped on RLC UM Loss tolerant and delay sensitive

eNB forwards only non-transmitted SDUs via X2 to target eNB If transmission was started but has not been successfully

received packets are lostMinimum complexity because context is not transferred

between eNB via X2 ROHC, COUNTS context is reset

106 3GPP TS 36.323, “E-UTRA; PDCP specification.”

Mobility in RRC_CONNECTED : Seamless Handover Seamless handover in the downlink

107

SDUs are transmitted to eNBin sequence

손실된패킷은재전송되지않음

전송하지못한패킷은 X2로전달

Reordering은 UE가수행

3GPP TS 36.323, “E-UTRA; PDCP specification.”

Mobility in RRC_CONNECTED : Lossless Handover Lossless handover OBJECTIVE : In-Sequence Delivery without Losses Possible because PDCP adds a sequence number to packets Applied for radio bearers that are mapped on RLC-AM Delay-tolerant and loss-sensitive

Un-acknowledged packets are forwarded via X2 an retransmitted they may be received twice

ROHC context is reset

108 3GPP TS 36.323, “E-UTRA; PDCP specification.”

Mobility in RRC_CONNECTED : Lossless Handover Lossless handover in the uplink

109

SDUs are delivered to the GW in sequence

Serving eNB transfers via X2, out-of-sequence SDUs

STATUS TRANSFER contains Sequence and Hyper Frame Numbers

Unacknowledged SDUs are retransmitted duplicity of P4

3GPP TS 36.323, “E-UTRA; PDCP specification.”

Mobility in RRC_CONNECTED : Lossless Handover Lossless handover in the downlink

110

SGW transmits End Marker to serving eNB

Target eNB knows when it can start to transmit SDUs from SGW

SDUs are delivered to the UE in sequence

3GPP TS 36.323, “E-UTRA; PDCP specification.”

Mobility in RRC_CONNECTED: Detailed Handover Procedure (1/3)

111

Adm

issio

n Co

ntro

l

S1-Based handover

Mobility in RRC_CONNECTED: Detailed Handover Procedure (2/3)

112

Mobility in RRC_CONNECTED: Detailed Handover Procedure (3/3)

113

Measurements

Measurement Configuration: RRCConnectionReconfiguration messageMeasurement objects: carrier frequency or list of cells Reporting configurations: RSRP/RSRQ, number of cellsMeasurement identities Quantity configurations: filteringMeasurement gaps: time periods

UE may measure and report Serving cell Listed cells Detected cells on a listed frequency

114RSRP: Reference Signal Received Power RSRQ: Reference Signal Received Quality

Measurements: Measurement report triggering

115

Event Condition

A1 Serving becomes better than threshold:

A2 Serving becomes worse than threshold:

A3Neighbor becomes offset better than Pcell:

A4 Neighbor becomes better than threshold:

A5PCell becomes worse than threshold1 and neighbor becomes better than threshold2:

1 & 2

A6(Rel-10)

Neighbour becomes offset better than SCell:

B1 Inter RAT neighbor becomes better than threshold:

B2PCell becomes worse than threshold1 and inter RAT neighbor becomes better than threshold2: 1 & 2

Mserving/Mn/Mp/Ms: measurement result of serving cell/neighbor cell/Pcell/SCell Of/Oc: frequency/cell specific offsetPCell: Primary (serving) Cell SCell: Secondary (serving) Cell <- carrier aggregation 3GPP, "TS 36.331 V10.5.0 Radio Resource Control (RRC) Protocol specification (Release 10)," ed, 2012.

Measurements: Reference Signal Received Power

RSRPUEs measure RSRP over

the cell-specific RSsPeriodic measurement Intra-freq.: 200ms Inter-freq.: 480ms

(proportion to the DRX cycle)

Requirements intra-frequency: 8 cells inter-frequency: 4 cells * 3

carriers = 12 cells

116

Measurements: Reference Signal Received Quality Reference Signal Received Quality (RSRQ)

RSRQ ∝

RSSI the total received power

• interference from all sources• serving and nonserving cells• adjacent channel interference and thermal noise

LTE Rel-8 RSRQ was applicable only in RRC_CONNECTED state

• Handover

LTE Rel-9 RSRQ was also introduced for RRC_IDLE

• Cell reselection

117RSSI : Received Signal Strength Indicator

Measurements: System Information Blocks

118ETWS: Earthquake and Tsunami Warning Service CMAS: Commercial Mobile Alert SystemMBMS: Multimedia Broadcast/Multicast Services

SIB Contents

MIB • parameters which are essential for a UE’s initial access to the network

SIB1 • parameters needed to determine if a cell is suitable for cell selection• information about the time-domain scheduling of the other SIBs

SIB2 • common and shared channel information

SIB3-8 • parameters used to control intra-frequency, inter-frequency and inter-RAT cell reselection

SIB9 • signal the name of a Home eNodeB (HeNBs)

SIB10-12 • ETWS notifications and CMAS warning messages

SIB13 • MBMS related control information

Measurements: RRC messages to transfer SI (example) MIB(SIB1) message is carried by PBCH(PDSCH) created every 40(80) msec broadcasted every 10(20) msec

Other SI messages are created and broadcasted dynamically on the PDSCH

119

Message Content Period ApplicabilityMIB Most essential parameter 40 ms Idle/connectedSIB1 Cell access related parameters, scheduling information 80 ms Idle/connected1st SI SIB2: Common and shared channel configuration 160 ms Idle/connected2nd SI SIB3: Common cell reselection information and intra-frequency cell

reselection parameters other than the neighbouring cell informationSIB4: Intra-frequency neighbouring cell Information

320 ms Idle only

3rd SI SIB5: Inter-frequency cell reselection information 640 ms Idle only4th SI SIB6: UTRA cell reselection information

SIB7: GERAN cell reselection information640 ms Idle only

PBCH: Physical Broadcast Channel PDSCH: Physical Downlink Shared ChannelSFN: System Frame Number

Paging

Pagingtransmit paging

information to a UE inRRC-IDLE -> RRC-CONNECTED

MME initiates pagingPhone callDL trafficSI changeETWS notification

120

eNB

[NAS: Service Request][eNB UE signalling connection ID]

Random access procedure

<RRC>Paging <S1AP>Paging

<NAS>Service Request

<S1-AP>Initial UE MESSAGE

<S1-AP>Initial Context Setup Request[NAS message]

[MME UE signaling connection ID][Security Context]

[UE Capability Information][Bearer Setup:serving S-GW TEID,

QoS Profile]

<RRC>Radio Bearer Setup

<RRC>Radio Bearer Setup Complete<S1-AP>Initial Context Setup Complete

[eNB UE signalling connection ID][Bearer Setup Confirm:eNB TEID]

P-RNTI check

Monitor PDCCH at certain UE-specific subframes

MMEUE

TA: Tracking Area PDCCH: Physical Downlink Control Channel RNTI: Radio Network Temporary IdentifierP-RNTI: Paging RNTI ETWS: Earthquake and Tsunami Warning service

Send to all eNBs in a TA

, S-TMSI

Paging: Tracking Area

TAI: Global Unique IDPLMN ID + TAC

In order to paging, MME needs TAI Ex) MME1 sends paging to

UE1 => broadcast all the eNBs in TAI1 & TAI2

TAI listUE receives TAI list when it is

connected

TAUWhen UE move out from

own TAI listPeriodic TAU

121TAI: Tracking Area Identifier TAC: Tracking Area Code TAU: Tracking Area Update

Control Plane ProtocolC-Plane OverviewMobility ControlRadio Resource ManagementSummary of C-Plane: Initial Attach Procedure

122

Radio Resource Management: RRM Functions

123

Power control Scheduling Cell search Cell reselection Handover Radio link or connection monitoring Connection establishment and re-establishment Interference management Location services Self-Optimizing network (SON)Network planning

Radio Resource Management: LTE RRM Characteristic

124MBMS: Multimedia Broadcast/Multicast Service

Characteristics DetailsInterference fluctuation • Fast time and frequency domain scheduling

Wide range of DRX • DRX: 0~2.5 sec

Different RATs • LTE, 3GPP & non-3GPP legacy RATs• Different channel structure

Various cell sizes • Macro / femto / pico• A few ‘m’ ~ tens of ‘km’

Various frame structure • FDD(synchronized or unsynchronized), TDD

Low latency requirements • Measurements & reports• HO

Power Control

LTE power control is not as critical as in WCDMA LTE uplink resources are orthogonal

-> no intra-cell interference (theory) frequency selective scheduling

Power ControlMaximize system capacityMinimize inter-cell interference

125SRSs: Sounding Reference Signals RB: Resource Block RE: Resource Element

Power Control: UL Power Control Uplink power control: PUSCH, PUCCH and the SRSs

(unit of RB) · ∆

Semi-static basic open-loop operating point : cell specific power level : factor to trade off the fairness of uplink scheduling against total

cell capacity• PUCCH: always 1 -> maximize fairness for cell edge UE

: downlink pathloss estimate calculated in the UE

dynamic offset updated from subframe to subframe ∆ : MCS dependent power offset : TPC command related power

• TPC command: relative power offset comparing to its previous Tx power, or absolute power

126

SRSs: Sounding Reference Signals RB: Resource Block RE: Resource ElementTPC: Transmitter Power Control 3GPP, "TS 36.213 v10.6.0 LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures

(Release 10)," July 2012.

Downlink power allocation (unit of RE) Cell specific RS EPRE (Energy per RE)

: semi-static (eNB signals UE)

10log : 0dB for all

transmission modes except multi-user MIMO

: UE specific parameter from higher layer

: 2 (transmit diversity with 4 antenna ports) or 1 (otherwise)

: cell specific parameter

from higher layer

PDSCH power to RS, where NO RSs are present, is UE specific and signaled by higher layer as .(ex. -4.77dB)

Cell-specific RS power, signaled in SIB2 (-60~50dBm)

Power Control: DL Power Allocation

127RE: Resource Element 3GPP, "TS 36.213 v10.6.0 LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures

(Release 10)," July 2012.

EPRE

Subcarrier Index[f]

PDCCH power depending on /

For PDSCH power in same symbol as RS an additional cell specific offset is applied, that is signaled by higher layers as (ex. -3.98dB)

Cell Search

Cell Search UE acquires the carrier frequency, timing and cell identity of

cells

Cell search within E-UTRAN Identify one of the 504 unique Physical Cell Identities (PCIs)

RequirementsMaximum permissible cell identification delay(∝ DRX cycle)Minimum synchronization signal quality : the energy per Resource Element (RE) of the synchronization

signal : total received energy of noise and interference on the same RE

128

Case Max. Delay Min. /Intra-frequencyDRX (0~40ms) 800ms -6dB

Inter-frequencyDRX(0~160ms) 3.84s -4dB

Radio Link Failure Handling

1st phase Layer 1 monitors downlink quality and indicates problems to RRC RRC filters L1 indications and starts a timer if no recovery within 1st phase, triggers 2nd phase

Layer 2 monitors random access attempts and indicates problems to RRC RRC triggers 2nd phase

2nd phase – Radio Link Failure (RLF): Possible recovery through an RRC Connection Reestablishment

procedure reestablishment may be performed in any cell to which the UE’s context

is made available If no recovery within 2nd phase, UE goes autonomously to IDLE

129

Inter-Cell Interference

LTE is designed for frequency reuse 1 (To maximize spectrum efficiency) All the neighbor cells are using same frequency channels no cell-planning to deal with the interference issues

Shared channels RB scheduled to cell edge user can be in high interference

->low throughput / call drops

Control channels Neighbor interference -> radio link failures at cell edge.

130

Inter-Cell Interference Coordination

ICIC mitigates interference on traffic channels only Power and frequency domain to mitigate cell-edge interference from

neighbor cells

X2 interface is used to share the information between the eNBs

A.Neighbor eNBs use different sets of RBs improves cell-edge SINR decrease in total throughput

B.Center users: complete range of RBsCell-edge users: different sets of RBs

C.Scheme B + different power schemes For center/cell edge user: low/high power

131

Control Plane ProtocolC-Plane OverviewMobility ControlRadio Resource ManagementSummary of C-Plane: Initial Attach Procedure

132

Summary of Control Plane: Initial Attach Procedure

133

Summary of Initial Attach Procedure

S-GW: Serving Gateway P-GW: Packet Data Network Gateway HSS: Home Subscriber Server PCRF: Policy and Charging Rule Function SPR: Subscriber Profile Repository IMSI: International Mobile Subscriber Identity Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011 http://www.netmanias.com/bbs/view.php?id=techdocs&no=74

Summary of Control Plane: Acquisition of IMSI

134

Summary of Initial Attach Procedure

Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: Acquisition of IMSI

135GUMMEI: Globally Unique MME ID ECGI: E-UTRAN Cell Global Identifier TAI:Tracking Area Identity Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: Authentication

136

Summary of Initial Attach Procedure

Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: Authentication

137MCC: Mobile Country Code MNC: Mobile Network CodePLMN: Public Land Mobile Network ID PLMN=MCC+MNC Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: NAS Security Setup

138

Summary of Initial Attach Procedure

Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: NAS Security Setup

139 Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: Location Update

140

Summary of Initial Attach Procedure

Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: Location Update

141APN: Access Point Name QCI: QoS Class identifier ARP: Allocation and Retention Priority AMBR: Aggregated Maximum Bit Rate Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: EPS Session Establishment

142

Summary of Initial Attach Procedure

Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: EPS Session Establishment (1)

143TEID: Tunnel Endpoint ID Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: EPS Session Establishment (2)

144TEID: Tunnel Endpoint ID Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: EPS Session Establishment (3)

145 Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011

Summary of Control Plane: EPS Session Establishment (4)

146

Summary of Control Plane

147

13

2 4 5

67 9

8 EMM- Registered

Summary

LTE network overview• Standardization of LTE/ Features of LTE/ LTE

Network Architecture/ LTE Physical layer

User plane protocol• PDCP/ RLC/ MAC

Control plane protocol• C-Plane Overview/ Mobility Control/ Radio Resource

Management/ Initial Attach Procedure

148

Thank you !

Q & A149

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