Interface Protocols

UMTS Interface Protocol

ZTE University

Content

Network Architecture Iu Interface Iur Interface Iub Interface Uu Interface Service Data Processing Flow

CN

UTRAN

UE

UMTS System Structure

UTRAN ： UMTS Terrestrial Radio Access Network CN ： Core Network UE ： User Equipment

UMTS Network Architecture

Analogy

Analogy

To start, we can divide a call into two parts: the signaling (or control) and data (or information). Already ahead of key concepts, we can understand the RRC as responsible for the control, and the RAB as responsible for the information part and represents the logical connection between the Ue and CN. RAB is service specific.

the RRC is in Layer 3 - control plane, while the RAB occurs between the UE

and CN, in the user plane.

Analogy

• On that fictitious scenario, the seller is the UTRAN, responsible for creating and maintaining the communication between the UE (buyer) and CN (deposit) so that the QoS requirements of each are met.

• The cliff is the Uu Interface between the UE and the UTRAN, and the road through the remote control car goes until the deposit is the Iu Interface, between the UTRAN and CN

• Sending requests and receipts is part of signaling, or the RRC. The shipment of purchases is the data part, or the RAB. In our scenario, the RRC are the Rails, and RAB is the full service of sending data between the UE and the CN.

• The railcars are the RBs, and convey the information in the radio path. These wagons define what type of thing will be transported, and in what quantity. Similarly, the RBs define what type of data will in the RRC, which can be Data or Signaling. When the QoS attributes change, then the Rbs associated with that RRC connection need to be reconfigured

• The remote control cars are the Iu bearer, and carry information on Iu Interface (between the UTRAN and the CN), either CS or PS.

What is a bearer?

Bearer: a bearer capability of defined capacity, delay and bit error rate, etc. (as defined in 3GPP specs.)

Bearer is a flexible concept designating some kind of ”bit pipe”

at a certain network level (see previous slide) between certain network entities

with certain QoS attributes, capacity, and traffic flow characteristics

Four UMTS QoS Classes

conversational, streaming, interactive, background

UMTS QoS (service) classes

ConversationalConversational StreamingStreaming InteractiveInteractive BackgroundBackground

low delay

low delay variation

video telephony/

conferencing

speechvideo streaming

audio streaming

low round-trip delay

www applications

delay is not critical

store-and- forward applications

(e-mail, SMS)

file transfer

reasonably low delay

basic applications

basic QoS requirements

End-to-End Service

UMTS Bear ServiceExternal Bear

Service

TE/MT Local

Bear service

Physical Bear

Service

UTRA FDD/TDD

Service

Backbone

Services

Iu Interface

Bear ServicesRB Services

RAB ServiceCN Bear

Service

TE CN

GatewayUTRANMT TE

CN Iu

EDGE

Node

UMTS

UMTS Bearing Services Structure

Universal model of the UTRAN interfaces

Application

Protocol

Data

Stream(s)

ALCAP(s)

TransportNetwork

Layer

Physical Layer

Signalling

Bearer(s)

Transport Network

User Plane

Control Plane User Plane

Transport

User

Network

Plane

Transport NetworkControl Plane

Radio

Network

Layer

Signalling

Bearer(s)

Data

Bearer(s)

Universal model of the UTRAN interfaces

Horizontal: UTRAN falls into 2 layers Radio Network Layer (RNL) Transport Network Layer (TNL)

Vertical: UTRAN falls into 4 planes Control plane User plane TNL control plane TNL user plane

In R99 and R4, the ATM technology is adopted at the transport network layer, while R5, IP transmission is introduced.

Content


Iu Interface

Node B

RNC

RNC

CS

Domain

PS

Domain

BC

Domain

Node B

Node B

Node B

UTRAN Core Network

(CN)

“Iu-CS”

“ Iu-PS”

“Iu-BC”

Iu Interface

Iu interface Functions RAB management

RAB setup, modification and release mapping of RAB characteristics to the Uu bearer mapping of RAB characteristics to the Iu transmission bearer RAB queuing, preemption and priority

Iu radio resource management Interacts with RRM function to analyze the current usage of radio resources to add or reject RAB request

Iu connection management Establishment and release of resources for Iu connection and managing the overload

Iu-UP (RNL) management Iu-UP frame protocol mode selection and protocol initialization

Mobility management Handovers SRNC relocation

Security management: Send Security Keys (Ciphering Keys) and the integrity Keys to UTRAN

Service and network access Paging coordination

Iu-CS Interface Stack Structure

Physical Layer

ATM

AAL 5 AAL 5

SSCF-NNI

SSCOP

Q.2150.1

AAL 2

Q.2630.1

RANAP

Radio Network

Layer

transport

Network Layer

Control Plane

transport Network Control

Plane

User Plane

Iu UP Protocol

Layer

MTP3b

SCCP

SSCF-NNI

SSCOP

MTP3b

transport Network User

Plane

transport Network User

Plane

Iu-CS Protocols

Radio Network Layer - Control Plane

RANAP : provides the signaling service between UTRAN and CN which is required to fulfill the RANAP functions :

Overall RAB Management Relocating SRNC Location reporting

Transport Network Layer- User Plane

SCCP : provides a service for transfer of messages between any two signaling points in the same or different network. It can act as connectionless or connection-oriented transport protocol.

Counter Unit

C310210956 Max setup time of RAB CS connection

Milisecond

Iu-PS Interface Stack Structure

Physical Layer

ATM

AAL 5

SSCF-UNI

SSCOP

RNSAP

Radio Network

Layer

Transport

Network Layer

Control Plane

Transport Network

Control Plane

User Plane

Iu UP Protocol

Layer

MTP3-B

SCTP

IP

SCCP

Transport Network User

Plane


Plane

Physical Layer

ATM

AAL 5

UDP

IP

GTP-U

M3UA

Iu-PS Protocols

Transport Network Layer- User Plane

AAL : ATM Adaptation Layer – To transmit higher protocols via ATM/IP, it is required to have adaptation sub layers. These sub layers contain a common adaptation and a service-specific adaptation part.

User plane data is carried by data bearers which use AAL 5 in case of Iu PS and AAL 2 in all other cases.

AAL2 connection is totally independent of ATM. Therefore it is still used in IP transmissions

C380020016 : The number of AAL2 resource requests that failed to modify to RNC because of no enough bandwidth in TrPath

Basic Processing Initial Message Response Message for Success

Response Message for Failure

Iu Release IU RELEASE COMMAND

IU RELEASE COMPLETE

Relocation Preparation

RELOCATION REQUIRED

RELOCATION COMMAND

RELOCATION PREPARATION FAILURE

Relocation Resource Allocation

RELOCATION REQUEST

RELOCATION REQUEST ACKNOWLEDGE

RELOCATON FAILURE

Relocation Cancel RELOCATION CANCEL

RELOCATION CANCEL ACKNOWLEDGE

SRNS Context Transfer

SRNS CONTEXT REQUEST

SRNS CONTEXT RESPONSE

Security Mode Control

SECURITY MODE COMMAND

SECURITY MODE COMPLETE

SECURITY MODE REJECT

Data Volume Report DATA VOLUME REPORT REQUEST

DATA VOLUME REPORT

Reset RESET RESET ACKNOWLEDGE

Reset Resource RESET RESOURCE RESET RESOURCE ACKNOWLEDGE

Iu Flow Overview

Basic Processing Message

RAB Release Request RAG RELEASE REQUEST

Iu Release Request IU RELEASE REQUEST

Relocation Detect RELOCATION DETECT

Relocation Complete RELOCATION COMPLETE

SRNS Data Forwarding Initiation SRNS DATA FORWARD COMMAND

SRNS Context Forwarding from Source RNC to CN FORWARD SRNS CONTEXT

SRNS Context Forwarding to Target RNC from CN FORWARD SRNS CONTEXT

Paging PAGING

Common ID COMMON ID

CN Invoke Trace CN INVOKE TRACE

CN Deactivate Trace CN DEACTIVATE TRACE

Location Reporting Control LOCATION REPORTING CONTROL

Location Report LOCATION REPORT

Initial UE Message INITIAL UE MESSAGE

Direct Transfer DIRECT TRANSFER

Overload Control OVERLOAD

Error Indiction ERROR INDICATION

Iu Flow Overview

Basic Processing Initial Message Response Message

RAB Assignment RAB ASSIGNMENT REQUEST

RAB ASSIGNMENT RESPONSE x N (N>=1)

Iu Flow Overview

Content


Iur Interface Stack Structure

Physical Layer

ATM

AAL 5 AAL 5

SSCF-UNI

SSCOP

STC(Q.2150.1)

AAL Type 2

ALCAP(Q.2630.1)

RNSAP

Control Plane User Plane

Iur Data Flow

MTP3-B

SCTP

IP

M3UA

SCCP

SSCF-UNI

SSCOP

MTP3-B

SCTP

IP

M3UA

Radio Network

Layer

Transport

Network Layer


Plane

Transport Network

Control PlaneTransport Network User

Plane

Iur interface Functions

Inter-RNC mobility management SRNC relocation, inter-RNC cell and UTRAN registration area update, inter-RNC paging, and

protocol error report.

Dedicated channel data transmission SRNC triggers measurement of dedicated resources in the DRNC.

Common channel data transmission setup and release of the transmission connection needed in common channel data stream

transmission of the Iur interface,

Global resource management transmission of inter-RNC cell measurement information. transmission of inter-RNC Node B timing information.

Serving RNC and Drift RNC in UTRAN

Core network

Iu

Iur

Iub

Iub

DRNC

SRNC

UEUE

BSBS

BSBS

RNCRNC

RNCRNC

Concept needed for:Soft handover between base stations belonging to different RNCs

Serving RNS (SRNS) Relocation

RNS = Radio Network Sub-system = RNC + all base stations controlled by this RNC

SRNS Relocation means that the Serving RNC functionality is transferred from one RNC (the “old” SRNC) to another (the “new”

SRNC, previously a DRNC) without changing the radio resources and without interrupting the user data flow.

RANAP provides the signalling facilities over the two Iu interfaces involved (Iu interfaces to “old” and “new” SNRC) for performing

SRNC Relocation in a co-ordinated manner.

SRNS Relocation (cont.)

Core network

Iu

Iur

Iub

Iub

DRNC

SRNC

UEUE

BSBS

BSBS

RNCRNC

RNCRNC Iu

SRNC

SRNC provides: 1) connection to core network

2) macrodiversity combining point

Soft handover concept

Iu

Iur

Iub

Iub

DRNC

SRNC

UEUE

BSBS

BSBS

RNCRNC

RNCRNC

Leg 1

Leg 3

Signal combining point is in

SRNC

(downlink: in UE)

BSBS Leg 2

Legs 1 and 2: Iur interface is not needed

Leg 3 is added: Iur interface is needed!

Core network

Parameter VALUE

Timer for Event 1D in HSPA or MBMS326ms. To 1280 ms

Event 1D hysterisis 4 dB

SRNC Wait Time for Relocation Preparation 60*100ms

Content


Iub Interface Stack Structure

Physical Layer

ATM

AAL Type 5 AAL Type 5

SSCF-UNI

SSCOP

Q.2150.1

SSCF-UNI

SSCOP

AAL Type 2

Q.2630.1

ALCAP

Node B

Application

Part (NBAP)

Radio

Network

Layer

Transport

Network Layer

Radio Network Control

Plane

Transport Network Control

Plane User Plane

Iub interface Functions

Management of the Iub interface transmission resources. Logic operation maintenance of Node B, including:

the cell configuration management radio network performance measurement common transmission channel management radio resource management

Transmission of application-related operation & maintenance data. System information management. Channel traffic management. Timing and synchronization management, including:

node synchronization transmission channel synchronization between the RNC and Node B

Iub interface

• Iub interface has a 16 Mbps bandwidth – 3G has a 10 Mbps and 2G has a 6 Mbps link

• Iub Bandwith is dynamic

BSC

RNC

BBU

RRU RRU

Content


RRC

MAC

Physical Layer

BMC

RLCRLCRLCRLCRLCRLCRLCRLC

PDCPPDCP

Transport Channel

Logical Channel

RB

Control

ControlControl

Control

Control

Control Plane signaling User Plane Message Uu Interface Edge

L1

L2/MAC

L2/RLC

L2/BMC

L2/PDCP

L3

Uu Interface Stack Structure

Uu Interface Stack Structure(1) Physical Layer Protocol

provides the MAC sublayer with transmission channel services. MAC Protocol (Media Access Control)

provides the RLC sublayer with logic channel services. RLC Protocol (Radio Link Control)

on the control plane, provides the RRC sublayer with signaling radio bearer services.

on the user plane, provides service radio bearer services together with the PDCP sublayer.

PDCP (Packet data convergence protocol) adapt different types of network layer protocols to the radio

interface. only exists in the packet domain

BMC (Broadcast main control) transfer broadcast and multicast information over the radio

interface.

Uu Interface Stack Structure(2)

RRC (Radio resource control) Provide services for the non-access layer, for example,

transmitting messages like call control, session management and mobility management at the control interface.

Setup, maintenance and release of an RRC connection between UE and UTRAN.

Setup, reconfiguration and release of radio bearer. Distribution, reconfiguration and release of radio resources used in

the RRC connection. RRC connection’s mobility function management. Request for QoS control. UE measurement report and report control. Outer loop power control, ciphering control, paging. Initial cell selection and reselection in the idle mode.

Camping on a UTRAN cell Camping on a GSM/GPRS cell

GPRS Packet Idle Mode

out of

service

in

service

out of

service

in

service

out of

service

in

service

Idle Mode

UTRA Connection Mode

CELL_FACHCELL_DCH

URA_PCH CELL_PCH

RRC Status and Migration Diagram

PDCP Function

User Data Transport: Transmit NAS data to RLC layer or reverse.

IP Head Compression: Compress or decompress the IP data in the Transport entities and receive entities. Different network layer has different compression algorithm.

Sequence Number Maintenance: If RB supports lossless SRNS Reselection, the Sequence Number can be kept synchronized between UE and RNC.

PDCP is only used in PS servicesPDCP is only used in PS services

BMC Services and Function

BMC services adopt TM or UM to provide Broadcast/Multicast services for the public users

The functions of BMC include cell broadcast message depository, service flow monitor, radio resource request for cell broadcast, BMC message scheduling, sending and receiving cell broadcast message and so on.

RLC Layer Work Modes

RLC provides the services for the upper layer: RLC connection setup/release, TM data Transport, UM data Transport, AM data Transport, unrecoverable error notify and so on.

The functions for RLC include Segment, Reassemble, Concatenation, Padding added, Data Transport, Error Detect, PDU delivery in order, Detection Repeat, Flow Control, Sequence Number Detection, Protocol Error Detection/ Retrieval/ Encryption/ Suspend function.

RLC work modes: TM, UM,AM. Different work mode is adopted according to the QoS requirement of different services; for the signaling, the work mode also depends on the significance.

MAC-Transport Channel Categories

BCH, Broadcast ChannelFACH, Forward Access ChannelPCH, Paging ChannelRACH, Random Access ChannelCPCH, Common Packet ChannelDSCH, DL Share Channel

DCH, Dedicated Channel

Common Transport Channel

Dedicated Transport Channel

Transport Block Transport Block Transport Block



Transport Block

Transport Block

Transport Block

Transport Block

Transport Block

Transport Block

Transport Block Transport Block

Transport Block

Transport Time Interval



MAC-Some Transport Channel Principles


Transport Block The basic switching unit between L1 and MAC layer

Transport Block Set A Set of Transport Blocks which are Transmitted in a Transport channel on a certain

moment. Transport Block Size

The bit number of a Transport Block. Transport Block Set Size

The bit number of a Transport Block Set. Transport Time Interval

Transport Time Interval is defined as a time interval for a Transport Block arrived, and it equals to the time for transporting a Transport Block on the Physical Layer of Radio Interface. It is always the gemination of MIN. interleaving cycle (10ms, Size of Radio Frame). MAC layer transports a Transport Block Set to the physical layer in each TTI.

Transport Format Transport Format is defined as the format of a Transport Block Set which is

transported on a Transport channel. The format is provided for MAC layer by L1 (or MAC layer provides for L1). The Transport Format is consisted of two parts: dynamical part and static part.


Transport Format Set Transport Format Set is defined as a set of Transport Format on a Transport

Channel. In side of a Transport Format Set the static part of transport format is the same. The previous two features of the dynamic part determine the instantaneous bit rate of the Transport channel.

Transport Format Combination When one or more transport channels map in L1, for each transport channel, there

should be a sets of Transport Format (Transport Format Set) available. For a certain time, not all the Format Combination is appropriate for L1, but only a sub-set, which is Transport Format Combination.

Transport Format Combination Set Transport Format Combination Set is defined as a set of Transport Format

Combination of Coded Composite Transport Channel (CCTrCH) . Transport Format Indicator

TFI is the specific indicator for a certain Transport Format among the Transport Format Set. It is used between L1 and MAC layer, when they exchange a transport block set.

Transport Format Combination Indicator TFCI is a indicator of the current Transport Format Combination.

The Services Provided by L1 and Timing Operation The Physical Layer provides Data Transport Services for

the upper layer, which are implemented by MAC sub-layer through Transport Channel.

Transport Format (or Transport Format Set) defines the feature of the transport channel, meanwhile, it also indicates the processing on the transport channel by physical layer, such as convolutional encoding and interleaving, rate match required by the services and so on.

The operation on the physical layer is strictly according to the timing of L1 Radio frame. And for every 10ms (or multiple times of 10ms) to generate a transport block.

Physical Layer Function

FEC encoding/decoding of transport channel To provide measurement and indicator for the upper layer (such as

FER, SIR, Interference Power, Transport Power and so on) Macro Diversity distribution/ Combination and soft handover

implementation Error Detection of transport channel Transport Channel multiplexing, Coding Combination Transport

Channel demultiplexing Rate Matching To map Coding Combination Transport Channel to physical channel Physical channel modulation/Frequency Spreading and

Demodulation/Frequency De-spreading Frequency and Timing (Chip, Bit, Slot, Frame) synchronization Close loop power control Physical channel power weight and combination RF Processing

Content


Radio Network Control-Plane protocol

RNC

CN

Node B

UE RNC

RANAP

RNSAP

NBAP

RRC

NBAP ： Node B Application Part

RANAP: Radio Access Network Application Part

RNSAP: Radio Network Subsystem Application Part

RRC: Radio Resource Control

AS and NAS

DCNtGC

UTRANUE Core Network

Access Stratum (AS)

Non-Access Stratum (NAS)

Radio(Uu) Iu

DCNtGC

DCNtGC DCNtGC DCNtGC DCNtGC

end AS entity end AS entity

Relay

UuStratum(UuS)

IuStratum

L2/L1

RRC

L2/L1

RRC

High Layer PDU

RLC SDU

High Layer PDU

RLCHeader

RLCHeader

MAC SDU MAC SDUMAC

HeaderMAC

Header

Transport Block Transport Block

CRC CRC

RLC SDU

……

……

……

……

……

High Layer

L2 RLC

(Non-Transparent Mode)

L2 MAC

(Non-Transparent Mode)

L1

Segment

And

Concatenation

Reassembly

Uu Interface Data Flow

The Physical Channel Forming Flow before Frequency Spreading

10 、 20 、 40 or 80ms

data

data

data

TrCH-i

dataCRC dataCRC dataCRC

data CRC data CRC data CRCd a t aCBL CBL CBL

0 、 8 、 16 or 24bits

Block Size Z ＝512 － Ktail ， CC

5120 － Ktail ， Turbo 码

CedBL CedBL CedBLCoded data CC or TCRate matched data

Rate matched data DTX

or

orData before 1st interleavingData after 1st interleaved

line of interleaver:1,2,4 or 8

Radio Frame

Radio Frame

Radio Frame

Number of Radio Frame:1,2,4 or 8

TrCH-1 TrCH-2 TrCH-ICCTrCHTrCH-1TrCH-2 TrCH-I DTXCCTrCH

Ph-1 Ph-2 Ph-P

In 10ms

In 10msPh-1 Ph-2 Ph-P

TPC TFCI pilot

Frequency Spreading, Scrambling



TrCH-i+1

data1 data2 TPC TFCI pilotdata1 data2 TPC TFCI pilotdata1 data2

Interface Protocols

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