UMTS Terrestrial Radio Access Network (UTRAN) Detach yes FFS, Contr expected Resource Management yes...

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UMTS Terrestrial Radio Access Network (UTRAN) UTRAN Architecture (Part 1) UMTS Terrestrial Radio Access (UTRA) and Radio Protocols UTRAN Architecture (Part 2) UTRAN Procedures (see separate presentation)

Transcript of UMTS Terrestrial Radio Access Network (UTRAN) Detach yes FFS, Contr expected Resource Management yes...

UMTS Terrestrial Radio Access

Network (UTRAN)

• UTRAN Architecture (Part 1)

• UMTS Terrestrial Radio Access (UTRA) and

Radio Protocols

• UTRAN Architecture (Part 2)

• UTRAN Procedures (see separate presentation)

Cellular Communication Systems 2Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

References

Books:

• Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks –Architecture, Mobility and Services. 2nd edition, Wiley, 2005

• Cornelia Kappler: UMTS Networks and Beyond, Wiley, 2009

• Holma, Toskala: WCDMA for UMTS. 4th edition, Wiley, 2007

Central 3GPP Documents on UTRAN:

• 25.401: UTRAN overview

• 25.301: Radio link protocols (UTRA)

• 25.931: UTRAN procedures

Cellular Communication Systems 3Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Architecture

Part 1:

• UTRAN Components and Interfaces

• UTRAN Functions

Cellular Communication Systems 4Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Components and Interfaces

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub Iub Iub Iub

UTRAN

Source: 3GPP 25.401

A Radio Network Subsystem (RNS) consists of a RNC and a number of Node B‘s

Cellular Communication Systems 5Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Architecture Principles – User Plane

Source: 3GPP 25.401

Non-Access Stratum (NAS):

• Protocols between UE and CN that are not terminated in the UTRAN

Access Stratum (AS): • Provides UE-CN transport service to NAS services• AS protocols are closely linked to radio technology

UTRAN

UE CN Access Stratum

Non-Access Stratum

Radio (Uu)

Iu

Radio proto- cols (1)

Radio proto- cols (1)

Iu protocols

(2)

Iu protocols

(2)

radio access bearer SAPs (user plane)

Cellular Communication Systems 6Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Architecture Principles – Control Plane

UTRAN

UE CN

Access Stratum

Non-Access Stratum

Radio (Uu)

Iu

Radio proto- cols (1)

Radio proto- cols (1)

Iu protocols

(2)

Iu protocols

(2)

CM,MM,GMM,SM (3)

CM,MM,GMM,SM (3)

Source: 3GPP 25.401

Non-Access Stratum control plane functions:

CM: Connection Management

MM: Mobility Management

GMM: GPRS MM

SM: Session Management

signaling connection

Cellular Communication Systems 7Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Functions (1)

- Transfer of User Data

- Functions related to overall system access control

- Admission Control

- Congestion Control

- System information broadcasting

- Radio channel ciphering and deciphering

- Integrity protection

- Functions related to mobility

- Handover

- SRNS Relocation

- Paging support

- Positioning

- Synchronisation

Source: 3GPP 25.401, Ch 7

Cellular Communication Systems 8Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Functions (2)

- Functions related to radio resource management and control

- Radio resource configuration and operation

- Radio environment survey

- Combining/splitting control

- Connection set-up and release

- Allocation and deallocation of radio bearers

- Radio protocols function

- RF power control

- Radio channel coding and decoding

- Channel coding control

- Initial (random) access detection and handling

- CN distribution function for Non Access Stratum messages

- Functions related to broadcast and multicast services (broadcast/multicast interworking function BM-IWF)

- Broadcast/Multicast Information Distribution

- Broadcast/Multicast Flow Control

- Cell-based Services (CBS) Status Reporting

- Tracing

- Volume reporting

Cellular Communication Systems 9Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Functions located inside/outside ASSource: 3GPP TS 23.110, Release 9

FUNCTION Non Access Stratum Access Stratum

Call set up/release yes no

(Connection) Bearer Set-Up Release CN bearer Radio Access Bearer

Supplementary Services yes no

Location management yes (IWF/CN related) yes (Radio related)

Attach/ Detach yes FFS, Contr expected

Resource Management yes (for NAS resource) yes (for AS resource incl. radio)

Handover yes* yes

Macrodiversity yes* yes

Encryption yes yes**

Authentication yes no

compression (non source dependent) yes yes

source dependent coding yes no

radio channel coding (could be many) no yes (could be many)

UE location identification may be supported yes

Charging yes no

NOTE *: Optionally execution. In some CNs, it may not be present but not full service will be supported (e.g. limited to

RLL type of service).

NOTE **: Contributions expected to clarify the role between encryption and subscriber data.

o

Cellular Communication Systems 10Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UMTS Terrestrial Radio Access (UTRA)

Radio Interface Protocols

• Air interface protocol architecture

• Layer 1, 2 and 3 protocols

• Mapping between logical, transport and physical channels

Cellular Communication Systems 11Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Radio Protocols – Overview

RLC

RRC

L1

GMM /

SM / SMS

RRC

MAC

ATM

RANAP

AAL5

Relay

ATM

AAL5

3G SGSNRNSMS

Iu-PsUu

RLC SCCP

Signalling

BearerMAC

L1

Signalling

Bearer

RANAP

SCCP

GMM /

SM / SMS

L1

RLC

PDCP

MAC

E.g., IP,

PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,

PPP

3G-SGSNUTRANMS

Iu-PSUu Gn Gi

3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

Layer 3

– IP (user plane)

– RRC (control plane)

Layer 2

– PDCP (user plane)

– BMC (user plane)

– RLC

– MAC

Layer 1

– PHY

See 3GPP 25.301 and

UMTS Networks book, ch. 9

Control plane

User plane

Cellular Communication Systems 12Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Source: 3GPP 25.301

Radio Protocol ArchitectureRadio Access BearersAS control plane SAPs

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Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

BMC L2/BMC

control

PDCP PDCP L2/PDCP

Radio

Bearers

RRC

Cellular Communication Systems 13Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

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Logical

Channel

s

Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

Radio Access BearersAS control plane SAPsPhysical Layer – Services

Transport channels do not define whatis transported (which is defined by logical channels)

Example: DCH offers the same type of service for control and user data

Physical layer offers information transfer services (transport channels) to

MAC and higher layers

Physical layer transport services define

–how and

–with what characteristics data are transferred over the radio interface

Cellular Communication Systems 14Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Radio Access BearersAS control plane SAPs

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Logical

Channel

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Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

Physical Layer – Channel Types

• common transport channels: there is a need for inband identification of the UEs when particular UEs are addressed

• dedicated transport channels: the UEs are identified by the physical channel, i.e. code and frequency for FDD (code, time slot and frequency for TDD)

Cellular Communication Systems 15Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Physical Layer – Common Transport Channels (1)

Random Access Channel (RACH)

• Contention based uplink channel used for transmission of relatively small amounts of data, e.g. for initial access or non-real-time dedicated control or traffic data

Forward Access Channel (FACH)

• Common downlink channel for relatively small amount of data

• no closed-loop power control

Downlink Shared Channel (DSCH) – TDD only

• Downlink channel shared by several UEs carrying dedicated control or traffic data

Uplink Shared Channel (USCH) – TDD only

• Uplink channel shared by several UEs carrying dedicated control or traffic data

Cellular Communication Systems 16Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Physical Layer – Common Transport Channels (2)

Broadcast Channel (BCH)

• Downlink channel used for broadcast of system information into an entire cell

Paging Channel (PCH)

• Downlink channel used for broadcast of control information into an entire cell allowing efficient UE sleep mode procedures

• Information types are paging and notification

High-Speed Downlink Shared Channel (HS-DSCH) – Rel. 5

• High-speed downlink channel shared by several UEs

Cellular Communication Systems 17Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Physical Layer – Dedicated Transport Channels & Transport Formats

Dedicated Channel (DCH)

Channel dedicated to one UE used in uplink or downlink

Enhanced Dedicated Channel (E-DCH)

• Channel dedicated to one UE used in uplink only

• Subject to Node-B controlled scheduling and HARQ

Transport Formats and Transport Format Sets

• A Transport Format or a Transport Format Set is associated with each transport channel

• A Transport Format defines the format offered by L1 to MAC (encodings, interleaving, bit rate and mapping onto physical channels)

• A Transport Format Set is a set of Transport Formats

• Example: a variable rate DCH has a Transport Format Set (one Transport Format for each rate), whereas a fixed rate DCH has a single Transport Format

Cellular Communication Systems 18Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Physical Layer Processing

DCH DCH DCH

DPCH DPCH

CRC attachment

Channel Coding

Rate Matching

CRC attachment

Channel Coding

Rate Matching

CRC attachment

Channel Coding

Rate Matching

Transport Channel Multiplexing

Physical Channel Mapping

Coded Composite Transport Channel (CCTrCH)

DataDataData Data

DataData

Transport

Block SetTransport

Block SetTransport

Block

Note: Physical Channel

Mapping is used to implement

multicoding (more than one

DPCH). This will usually

only be used for high data

rates

Note: Functional blocks

which implement

concatenation, segmentation,

interleaving, discontinuous

transmission (DTX) and

macrodiversity

distirbution/combining have

been suppressed.

See 3GPP 25.302 for details

o

Physical Channels

Transport Channels(PHY SAP)

Cellular Communication Systems 19Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Physical Layer – Functions

• Macrodiversity distribution/combining and soft handover execution

• Error detection on transport channels and indication to higher layers (CRC)

• FEC encoding/decoding and interleaving/deinterleaving of transport channels

• Multiplexing of transport channels and demultiplexing of coded composite transport channels

• Rate matching (fit bits into physical channel)

• Mapping of coded composite transport channel on multiple physical channels

• Power weighting and combining of physical channels

• Modulation and spreading/demodulation and despreading of physical channels

• Frequency and time (chip, bit, slot, frame) synchronisation

• Measurements and indication to higher layers (e.g. frame error rate, signal-to-interference ratio, interference power, transmit power, etc.)

• Closed-loop power control

• RF processing

• Support of timing advance on uplink channels (TDD only)

• Support of Uplink Synchronisation (TDD only)

Cellular Communication Systems 20Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

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Logical

Channel

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Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

Radio Access BearersAS control plane SAPs

Medium Access Control (MAC) – Services

Data transfer (logical channels SAPs)

– Unacknowledged transfer of MAC SDUs between peer MAC entities

– No data segmentation (performed by higher layers) in R.99

Reallocation of radio resources and MAC parameters

– Execution of radio resource reallocation and change of MAC parameters by request of RRC, i.e. change of transport format (combination) sets, change of transport channel type

– Autonomous resource allocation in TDD mode

Reporting of measurements

– Local measurements such as traffic volume and quality indication (reported to RRC)

Cellular Communication Systems 21Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

MAC – Logical Channels

• Control Channels (transfer of control plane information)

– Broadcast Control Channel (BCCH) – DL

– Paging Control Channel (PCCH) – DL

– Common Control Channel (CCCH) – DL/UL

– Dedicated Control Channel (DCCH) – DL/UL

– Shared Channel Control Channel (SHCCH) – DL/UL (TDD)

• Traffic Channels (transfer of user plane information)

– Dedicated Traffic Channel (DTCH) – DL/UL

– Common Traffic Channel (CTCH) – DL/UL

Logical channels define what information is transported

(transport channels (PHY SAP) define how data are transported)

o

Cellular Communication Systems 22Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

MAC – Functions (1)

PHY PHY

ATM

DschFP

IubUE NodeB CRNCUu Iur SRNC

AAL2

ATM

DschFP

MAC-c/sh

ATM ATM

MAC-d

DCCH DTCH

AAL2

MAC-c/sh

MAC-d

DTCH DCCH

AAL2

DschFP

AAL2

DschFP

• Mapping between logical channels and transport channels

• Selection of appropriate Transport Format for each Transport Channel depending on instantaneous source rate

• Priority handling (multiplexing) between data flows of one UE (MAC-d)

• Priority handling (scheduling) between different UEs (MAC-c/sh)

• Identification of UEs on common transport channels

Example: DTCH/DCCH mapped on DSCH (TDD only)

Cellular Communication Systems 23Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

MAC – Functions (2)

PHY PHY

ATM

DschFP

IubUE NodeB CRNCUu Iur SRNC

AAL2

ATM

DschFP

MAC-c/sh

ATM ATM

MAC-d

DCCH DTCH

AAL2

MAC-c/sh

MAC-d

DTCH DCCH

AAL2

DschFP

AAL2

DschFP

• Multiplexing/demultiplexing of upper layer PDUs on common transport channels

• Multiplexing/demultiplexing of upper layer PDUs on dedicated transport channels

• Traffic volume measurement

• Transport channel type switching (controlled by RRC)

• Ciphering for transparent RLC mode

Example: DTCH/DCCH mapped on DSCH (TDD only)

Cellular Communication Systems 24Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Logical/ Transport/ Physical Channels Mapping (excerpt, FDD)

BCCH

PCCH

CCCH

DCCH

DTCH

CTCH

BCH

DCH

RACH

FACH

PCH

P-CCPCH

S-CCPCH

P-CPICH

PRACH

DPDCH

DPCCH

PICH

P-SCH

S-SCH

AICH

S-CPICH

Logical Channels

(MAC SAP)

Transport Channels

(PHY SAP)

Physical Channels

DPCH

Key: Uplink

Downlink

Bidirectional

Data Transfer

Association

Control Ch

Traffic Ch

Common Ch (no FPC)

Common Ch (FPC)

Dedicated Ch (FPC) Info Channels

Assoc Channels

Fixed Channels

o

Notes:

• Figure deschribes a subset of the possible mappings only! See 25.301, sc. 5.6 or following slides for the complete list of possible mappings.

• FPC denotes Fast Power Control

Cellular Communication Systems 25Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

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Logical

Channel

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Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

• Transparent data transfer (TM)• Unacknowledged data transfer (UM)• Acknowledged data transfer (AM)

Radio Link Control (RLC)

Cellular Communication Systems 26Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RLC – Services (1)

Transparent data transfer (TM)

• Transmission of upper layer PDUs without adding any protocol information (no RLC header)

• Possibly including segmentation/reassembly functionality

Unacknowledged data transfer (UM)

• Transmission of upper layer PDUs without guaranteeing delivery to the peer entity

– Error detection: The RLC sublayer shall deliver only those SDUs to the receiving upper layer that are free of transmission errors by using the sequence-number check function

– Immediate delivery: The receiving RLC sublayer entity shall deliver a SDU to the upper layer receiving entity as soon as it arrives at the receiver

Acknowledged data transfer (AM)

• Transmission of upper layer PDUs and guaranteed delivery to the peer entity

• Notification of RLC user at transmitting side in case RLC is unable to deliver the data correctly

• in-sequence and out-of-sequence delivery

• error-free delivery (by means of retransmission)

• duplication detection

Cellular Communication Systems 27Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RLC – Services (2)

Maintenance of QoS as defined by upper layers

• retransmission protocol configurable by layer 3 to provide different levels of QoS

Notification of unrecoverable errors

• RLC notifies the upper layer of errors that cannot be resolved by RLC itself by normal exception handling procedures

There is a single RLC connection per Radio Bearer

Cellular Communication Systems 28Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RLC – Functions

• Transfer of user data (AM, UM, TM)

• Segmentation and reassembly (RLC PDU size adapted to transport format)

• Concatenation

• Padding

• Sequence number check (UM mode)

• Duplicate RLC PDUs detection

• In-sequence delivery of upper layer PDUs

• Error correction (selective-repeat ARQ)

• Flow control between RLC peers

• SDU discard

• Protocol error detection and recovery

• Exchange of status information between peer RLC entities

• Ciphering (non-transparent mode)

• Suspend/resume and stop/continue of data transfer

• Re-establishment of AM/UM RLC entity

Convert variable-size higher

layer PDUs into fixed-size

RLC PDUs (TBs)

Convert radio link

errors into packet

loss and delay

Avoid Tx and Rx

buffer overflows or

protocol stalling

Cellular Communication Systems 29Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Logical/Transport Channels Mapping Details

UTRAN side

Broadcast

Channel

(BCH)

Paging

Channel

(PCH)

Forward

Access

Channel

(FACH)

Random

Access

Channel

(RACH)

Dedicated

Channel

(DCH)

BCCH-

SAP

DCCH-

SAPCCCH-

SAP

PCCH-

SAPDTCH- SAP

Transport

Channels

MAC SAPs

CTCH-

SAP

To / From Physical Channels

Logical

Channels

Broadcast

Control

Channel

(BCCH)

Paging

Control

Channel

(PCCH)

Dedicated

Control

Channel

(DCCH)

Common

Control

Channel

(CCCH)

Common

Traffic

Channel

(CTCH)

Dedicated

Traffic

Channel

(DTCH)

U

D

U/D Uplink / Downlink

Uplink

Downlink

U DDDU/D

U/DD D U/D U/DD

Tr

Tr

Tr

UM

AM

UM

AM

Tr

Tr

UM

AM

UM

UM

AM

UM

AM Tr

UM

AM

UM

Control

Plane

User

Plane

RLC Modes

Tr Transparent

UM Unacknowledged

AM Acknowledged

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Cellular Communication Systems 30Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Control Plane Relationships

RLC

Call signalling: RLC Entities / Channels / Signaling Radio Bearers (SRB) Relationships

Abbr. Mode RLC Entities

Tr Transparent mode 2 (one Tx and one Rx)

UM Unacknowleged Mode 2 (one Tx and one Rx)

AM Acknowleged Mode 1 (bi-directional for ARQ)

SRB1 SRB2 SRB3/4

Notes:

This is for a single user and only shows

the control plane. SRB0 is not shown as

this is for the CCCH - i.e. not used for a

dedicated call, only for establishment.

RLC Entity RLC EntityUM RLC EntityAM RLC EntityAM

MAC

Logical

ChannelsDCCH DCCH DCCH DCCH

DCH

LAYER 1 CCTrCH

DCH

CCTrCH

DPDCH DPDCH

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Cellular Communication Systems 31Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Circuit-Switched Voice Call Relations

RL

C

Call signalling: RLC Entities / Channels / Radio Bearers (RB)

Relationships

Abbr. Mode RLC Entities

Tr. Transparent mode 2 (one tx. and one rx.)

UM Unacknowleged Mode 2 (one tx. and one rx.)

AM Acknowleged Mode 1 (bi-directional for ARQ)

SRB1 SRB2 SRB3/4

Notes:

This is for a single user. SRB0 is not shown as this

is for the CCCH - i.e. not used for a dedicated call,

only for establishment.

RLC Entity RLC EntityUM RLC EntityAM

MAC

DCCH DCCH DCCH DCCH

LAYER 1CCTrCH

RLC

RLC

RLC

RLC

RLC

RLC

Cla

ss A

(81bits)

Cla

ss B

(103bits)

Cla

ss C

(60bits)

AM

R V

OIC

E C

OD

EC

DL

Cla

ss A

(81bits)

Cla

ss B

(103bits)

Cla

ss C

(60bits)

AM

R V

OIC

E C

OD

EC

UL

Tr

RB

RB

RB

RB

RB

RB

DTCH DTCH

Control Plane

Use

r P

lan

e

DCH DCH

DPDCHPhysical

Channels

RLC EntityAM

DCH DCH

CCTrCH

DPDCH

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Cellular Communication Systems 32Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

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Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

Radio Access BearersAS control plane SAPsPacket Data Convergence Protocol (PDCP)

Service: PDCP SDU delivery PDCP is defined for PS domain only!

Cellular Communication Systems 33Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

PDCP – Functions

Header compression and decompression

• Header compression and decompression of IP data streams (e.g. TCP/IP and RTP/UDP/IP headers)

Header compression method is specific to the upper layer protocol combinations, e.g. TCP/IP or RTP/UDP/IP (RFC 2507 & RFC 3095)

Transfer of user data

• PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa

Support for lossless SRNS relocation

• Maintenance of PDCP sequence numbers for radio bearers that are configured to support lossless SRNS relocation

Cellular Communication Systems 34Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

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Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

Broadcast/Multicast Control (BMC)

Functions:

• Storage of Cell Broadcast Messages

• Traffic volume monitoring and radio resource request for CBS

• Scheduling of BMC messages

• Transmission of BMC messages to UE

• Delivery of Cell Broadcast messages to upper layer (NAS) in the UE

Service:

• broadcast/multicast transmission service in the user plane for common user data in unacknowledged mode

o

Cellular Communication Systems 35Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

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Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC

RLC RLC

RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

Radio

Bearers

RRC

Radio Resource Control (RRC)

Services Provided to Upper Layers

General Control (GC) – information broadcast service

Notification (Nt) – paging and notification broadcast services

Dedicated Control (DC) – connection management and message transfer

Cellular Communication Systems 36Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RRC – Interaction with Lower Layers

R R C R R C

R L C R L C

Radio Resource

Assignment

[Code, Frequency,

TS, TF Set, Mapping,

etc.]

Measurement Report

RLC retransmission

control

L 1 L 1

U T R A N U E

Co

ntr

ol

Mea

sure

men

ts

Co

ntr

ol

Mea

sure

men

ts

Co

ntr

ol

Mea

sure

men

ts

Co

ntr

ol

Mea

sure

men

ts

M A C M A C

Co

ntr

ol

Co

ntr

ol

Cellular Communication Systems 37Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RRC – Functions

RRC handles the control plane signaling of layer 3 between the UEs and UTRAN:- Broadcast of information provided by the non-access stratum (Core Network) - Broadcast of information related to the access stratum- Establishment, re-establishment, maintenance and release of RRC

connections- Establishment, reconfiguration and release of Radio Bearers (L2 SAPs)- Assignment, reconfiguration and release of radio resources for the RRC

connection- RRC connection mobility functions- Paging/notification- Routing of higher layer PDUs on UE- Control of requested QoS- UE measurement reporting and control of the reporting- Outer loop power control- Control of ciphering- Slow DCA (TDD)- Arbitration of radio resources on uplink DCH- Initial cell selection and re-selection in idle mode- Integrity protection (message authentication for sensitive data)- Control of Cell Broadcast Service (CBS)- Timing advance control (TDD)

Cellular Communication Systems 38Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RRC State Machine

• RRC state machine exists as two peer entities (MS and UTRAN)

• The two peer entities are synchronized (apart from transient situations and error cases)

Idle mode

Cell

Connected

RRC

connection

establishment

URA

Connected

RRC

connection

release

Enter URA

connected state

Enter cell

connected state

Connected mode

Cellular Communication Systems 39Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Registration Area (URA)

LA

RA

RA

RA RA

RA

RA RA

RA

RA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

• URA is known to the

UTRAN only

• URA is established in

RRC connected mode

URA is independent of RNC area

URA may cover

•part of an RNC area

•parts of several RNC areas

URAs may overlap

URA

URAURA U

RA

URA

URA

URA

URA

URA

URA

URA

Cellular Communication Systems 40Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RRC State Machine

Idle mode

Cell

Connected

RRC

connection

establishment

URA

Connected

RRC

connection

release

Enter URA

connected state

Enter cell

connected state

Connected mode

RRC Idle mode:

– no connection established between the MS and UTRAN

– no signalling between UTRAN and the MS except for system information sent from UTRAN on a broadcast channel to the MS

– MS can only receive paging messages from a CN identity on the PCH

– no information of the MS isstored in UTRAN

Cellular Communication Systems 41Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

RRC State Machine

RRC Connected mode:

– two main states • Cell Connected: MS position is known at the cell level; RRC connection

mobility is handled by handover and cell update procedures

• URA Connected: MS position is known at the URA level; URA updating procedures provide the mobility functionality; no dedicated radio resources are used in the state.

– there is one RNC that is acting as serving RNC, and an RRC connection is established between the MS and this SRNC

An UE has either zero or one RRC connection

Idle mode

Cell

Connected

RRC

connection

establishment

URA

Connected

RRC

connection

release

Enter URA

connected state

Enter cell

connected state

Connected mode

Cellular Communication Systems 42Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UMTS RRC State Optimization (PS mode)

Goal: Minimization of Radio Resource Consumption during Idle Times

Tradeoff for idle periods

• retaining in state => continuous state cost or

• move to cheaper state => transition cost

Limited resources

• radio resources (transmit power)

• channelization codes

• processing cost (signaling)

• power consumption

• transport resources (Iu, Iub, …)

Find optimal timeout settings depending on

• traffic model (distribution of idle times)

• cost per state and scarcity of allocated resources

• cost per transition

• user mobility

• …

cell_DCH

URA_PCH

cell_PCH

idle

T1

T2

T3

Cellular Communication Systems 43Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UMTS RRC State OptimizationO

ptim

ization o

f Tim

eout

Valu

es

sum

state cost

transition cost

Cellular Communication Systems 44Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Architecture

Part 2:

•Macro diversity: Serving and Drift RNC

•UTRAN architecture details and protocols

•AS and NAS services

•RRC connection and signaling connection

Cellular Communication Systems 45Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Macro Diversity:Serving and Drift RNS

Serving RNS (SRNS)

Core Network

Iu

Drift RNS (DRNS) Iur

UE

Cells

Source: 3GPP 25.401

Each RNS is responsible for the resources of its set of cells

For each connection between User Equipment (UE) and the UTRAN, one RNS is the Serving RNS (SRNS)

Drift RNSs (DRNS) support the Serving RNS by providing radio resources

Macro-diversity and handover is jointly supported by Node B(s) and RNC(s)

Cellular Communication Systems 46Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Serving, Drift and Controlling RNC

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub Iub Iub Iub

UTRAN

UE

SRNCDRNC

Softer handover:

maximum ratio combiningin Node B

Soft handover:

radio frame selection (layer 1) in SRNC (and DRNC)

Cellular Communication Systems 47Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Roles of RNSs/RNCs

Serving RNS (SRNS)

• A role an RNS can take with respect to a specific connection between a UE and UTRAN

• There is one Serving RNS for each UE that has a connection to UTRAN

• The Serving RNS is in charge of the RRC connection between a UE and the UTRAN

• The Serving RNS terminates the Iu for this UE

Drift RNS (DRNS)

• A role an RNS can take with respect to a specific connection between a UE and UTRAN

• An RNS that supports the Serving RNS with radio resources when the connection between the UTRAN and the UE need to use cell(s) controlled by this RNS

Controlling RNC (CRNC)

• A role an RNC can take with respect to a specific set of UTRAN access points (an UTRAN access point is specific to a cell)

• Exactly one Controlling RNC serves an UTRAN access point (i.e. each cell)

• The Controlling RNC has the overall control of the logical resources of its UTRAN access points

Source: 3GPP 21.905

Cellular Communication Systems 48Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Distribution of Functions between RNCs

Radio resource management:

• CRNC owns the radio resources of a cell

• SRNC handles the connection (RRC/RANAP) to one UE, and may borrow radio resources of a certain cell from the CRNC

• SRNC performs dynamical control of power for dedicated channels, within limits admitted by CRNC

Inner loop power control for some radio links of the UE connection may be done by the Node B

Inner loop control is controlled by an outer loop, for which the SRNC has overall responsibility

• SRNC handles scheduling of data for dedicated channels

• CRNC handles scheduling of data for common channels (no macro diversity on DL common channels)

Source: 3GPP 25.401, Ch 6.3

Cellular Communication Systems 49Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Serving, Drift and Controlling RNC

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub Iub Iub Iub

UTRAN

UE 1

SRNCDRNC

UE 2

common/shared channel

SRNC

dedicated channel in

macro-diversity mode

Cellular Communication Systems 50Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Architecture: Functional Split

Control plane

Bearer plane

Core Network

Node-B

Paging

Com./ SharedChannel

Processing

Cell Control

DedicatedChannel

Processing

Mobile Control

Broadcast

CRNC/DRNC SRNC

Cellular Communication Systems 51Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Core Network

User plane Control plane

Iub Iur

paging (connected)

paging

(connected,

PCCH)

MAC-b

RLC-b

RRC-b

BCCH

BCH

PHY

Softer Handover

Splitting /

Combining

N

B

A

P

Iub

CCH

FP

Node-B

Iub/Iur

DCH

FP

Iu

Soft Handover

Splitting /

Combining

optional

CTCHPCCH

BCCH

N

B

A

P

R

N

S

A

P

Iur

CCH

FP

Iub

CCH

FP

Iub/Iur

DCH

FP

Iub/Iur

DCH

FP

RANAPCRNC

paging (idle)

DRNC

BM-IWF

PCH RACH

FACH

DSCH

CPCH

CCCH

RLC-c/sh

MAC-c/sh

BMC

RRC-c/sh

SABP

Iu

MAC-d

DCH

DTCH

RLC-d

PDCP

RRC-d

Soft Handover

Splitting /

Combining

DCCH

SRNC

R

N

S

A

P

RANAP

Iur

CCH

FP

Iub/Iur

DCH

FP

Iu-CS

FP

Iu-PS

FP

LOGICAL

CHANNELS

TRANSPORT

CHANNELS

UTRAN Protocol Architecture: Summary

o

Cellular Communication Systems 52Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Mapping of Layers to NodeB, CRNC and SRNCR

LC

, e

tc.

PH

YM

AC

Node B

CCCH DCCH, DTCH

MA

C-c

/sh

MA

C-d

MA

C-d

PHY-upper

RL

C,

etc

.

RL

C,

etc

.

Controlling RNC Serving RNC

Iub Iur

PC

H

FA

CH

RA

CH

DS

CH

US

CH

DC

H

FA

CH

RA

CH

DS

CH

US

CH

DC

H

Common Ch (no fast power control)

Common Ch (fast power control)

Dedicated Ch (fast power control)

Control Ch

Traffic Ch

Logical Channels Transport Channels

o

Cellular Communication Systems 53Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Wrap-up: Why is UTRAN so complicated?

Some answers:

• Radio resources are the limiting factor

• CDMA macro-diversity mode

– Single RLC/MAC entity required for synchronous delivery of radio

frames over all SHO legs

– Splitting/combining of radio frames (multicast)

• Tight handover requirements esp. for voice

– Need for proactive handover initiation requires interaction between

radio layers

• Designed for maximum functionality and flexibility

– Overdimensioned from the viewpoint of a single application

Cellular Communication Systems 54Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Radio Protocols in Context

PHY PHY

ATM

DchFP

ATM

MAC-d

IubUE NodeB CRNCUu SRNC

ATM ATM

Iur

MAC-d

DCCH DTCH

DchFP

PHY-upper PHY

AAL2 AAL2

DTCH DCCH

AAL2 AAL2

DchFP DchFP

PHY

Transport Network Layer (TNL)

Radio Protocols (UTRA)

Radio Network Layer (RNL)

o

Radio protocols terminated in different entities (NodeB, CRNC, SRNC)

Radio Network Layer to support external interfaces and split of UTRA functionality

Transport Network Layer to support L2 transport (ATM or IP) between entities

Example: DCH (user plane)

Cellular Communication Systems 55Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UTRAN Protocol Reference Model

Radio Protocols (UTRA)

• Protocols constituting the radio interface

Radio Network Layer (RNL)

• UTRAN-specific protocols to control the management and use of radio access bearers across the UTRAN interfaces (Iu, Iub, Iur)

• Protocols handling the distribution of the radio protocols over multiple physical entities

• User plane: frame protocols (FP), e.g. DchFP

• Control plane: application part (AP) protocols, e.g. RANAP, NBAP, RNSAP

Transport Network Layer (TNL)

• Set of general „transport“ protocols allowing non-adjacent network nodes to communicate

• ATM transport or IP transport (Release 4 and beyond)

o

Cellular Communication Systems 56Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Serving and Controlling RNCExample: DCH (Dedicated Channel – UL&DL macro diversity)

PHY PHY

ATM

DchFP

ATM

MAC-d

Iub UE NodeB CRNC Uu SRNC

ATM ATM

Iur

MAC-d

DCCH DTCH

DchFP

PHY-upper PHY

AAL2 AAL2

DTCH DCCH

AAL2 AAL2

DchFP DchFP

PHY

Source: 3GPP 25.401, sc 11.2.4 (see also 25.301, sc 5.6.1)

Combining/splitting of

phy. channels

Combining/splitting is supported for DCH only

(no layer 2 processing in Node B and DRNC)

cells servedby the same

node B

cells servedby the same

CRNC (optional)

cells servedby different

RNCs

Cellular Communication Systems 57Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

PHY PHY

ATM

FachFP

IubUE NodeB CRNCUu Iur SRNC

AAL2

ATM

FachFP

MAC-c/sh

ATM ATM

MAC-d

DCCH DTCH

AAL2

MAC-c/sh

MAC-d

DTCH DCCH

AAL2

FachFP

AAL2

FachFP

Serving and Controlling RNCExample: FACH (Forward Access Channel – DL, no macro diversity)

Physical channel is terminated within node B (no support for combining/splitting)

Common MAC (MAC-c/sh) terminates in the CRNC

Dedicated MAC (MAC-d) terminates in the SRNC

Source: 3GPP 25.401, sc 11.2.3 (see also 25.301, sc 5.6.2)

CCCHCCCH

Cellular Communication Systems 58Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Example: BCH (Broadcast Channel – DL, system information)

UE NodeB

RLC

MAC

PHY

RLC

MAC

PHY

RRC

RRC

RRC

CRNC

Source: 3GPP 25.301, sc 5.6.7

RRC terminates in

• CRNC: provides broadcast information distributed by node B

• Node B: handles periodic repetition of broadcast information

Splitting of RRC eliminates repetition of broadcast data on Iub interface

o

Cellular Communication Systems 63Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Access Stratum Services Revisited

DC Nt GC

UTRAN UE Core Network

Access Stratum (AS)

Non-Access Stratum (NAS)

Radio (Uu) Iu

DC Nt GC

DC Nt GC DC Nt GC DC Nt GC

DC Nt GC

end AS entity end AS entity

Relay/RNC functions

Uu Stratum (UuS)

Iu Stratum

L2/L1

RRC

L2/L1

RRC

Source: 3GPP 25.301

(see also 3GPP 23.110)

Services of Access Stratum:• General Control (GC) – general network-specific broadcasts• Notification (Nt) – UE-specific infos• Dedicated Control (DC) – connected mode• User data transfer (RAB) – connected mode

Note: NAS signaling services are provided by RANAP

Cellular Communication Systems 64Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Services provided at AS SAPs –GC and Nt (UE in idle mode)

General Control SAPs (GC) – information broadcast service

– Enable CN to provide information and to give commands that do not relate to specific users or specific sessions (group calls, conference)

– Typically one GC SAP per AN/CN connection point (Iu)

– Typically one GC SAP in MS

Notification SAPs (Nt) – paging and notification broadcast services

– SAPs are used to broadcast data to identified users

– Typical use is for initiating paging in the AN

– Typically one Nt SAP per AN/CN connection point (Iu)

– Typically one Nt SAP (a Paging SAP) in MS

Source: 3GPP 23.110, ch. 6; see also 25.301, ch 5.4

o

Cellular Communication Systems 65Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Services provided at AS SAPs – DC (conn. mode)

Dedicated Control SAPs (DC) – connection establishment/release and message transfer

• SAPs are used to establish and release connections with specific UEs, and to transfer information on these connections

• Several types of connections are identified, point connections (single user) and group connections

• SAPs are identified by a SAPI at the AS boundary

• SAPI is valid for the lifetime of a connection

• SAPI is used as a unambiguous connection identifier of the associated SAP

• Typically a great number of DC SAPs per AN/CN connection point

• Typically a single DC SAP in MS

Source: 3GPP 23.110

o

Cellular Communication Systems 66Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

UE mode

HLR

GGSN

Side note: modes, states and hierarchy (PS mode, AS and NAS)

SGSN

RNC

UE

RRC connection

Signaling connection

PMM state (detached, idle, connected)

SM: PDP context (active, inactive)

Cellular Communication Systems 67Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Radio Link, RRC Connection & Signaling Connection

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub Iub Iub Iub

UTRAN

UE

radio link

RRC connection -> connected mode

signaling connection

SRNC

RRC connections and signaling connections are logical links

Cellular Communication Systems 68Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Radio Link, RRC Connection & Signaling Connection

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub Iub Iub Iub

UTRAN

UE

radio link

SRNCDRNC

RRC connection

signaling connection

Cellular Communication Systems 69Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

MSC/VLRor SGSN

SRNCUE

RRC Connection and Signaling Connection

RRC Connection RANAP Connection

RRC RANAPRRC RANAP

Signaling Connection

Radio Access Bearer

Signaling Radio Bearer Iu Signaling Bearer

Higher layer control

Higher layer control

Cellular Communication Systems 70Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Signaling Connection

• No signaling connection exist (idle state)

– UE has no relation to UTRAN, only to CN

– no data transfer

– paging identification by IMSI, TMSI, P-TMSI

• Signaling connection exist (connected state)

UE position can be known on different levels:

- URA level (UTRAN registration area): URA is a specified set of cells, which can be identified on the BCCH.

- Cell level: Different channel types can be used for data transfer:

- Common transport channels (RACH, FACH, DSCH, USCH)

- Dedicated transport channels (DCH)

Source: 3GPP 25.301, ch 6.2

Cellular Communication Systems 71Andreas Mitschele-Thiel, Jens Mueckenheim Oct-17

Recap on Important Vocabulary

RRC connection

• point-to-point bi-directional connection between RRC peer entities on the UE and the UTRAN sides

• UE has either zero or one RRC connection

Signaling connection

• an acknowledged-mode link between the UE and the CN to transfer higher layer information between the entities in the non-access stratum (via RRC and RANAP)

Radio link

• a logical association between a single UE and a single UTRAN access point (cell)

• its physical realization comprises one or more radio bearer transmissions

Radio bearer (compare signaling radio bearer)

• service provided by the RLC layer for transfer of user data between UE and SRNC

Radio interface

• interface between UE and a UTRAN access point

• radio interface encompasses all the functionality required to maintain the interface

Source: 3GPP TR 21.905