01-Chapter 1 UTRAN Interface Protocols and Functions.pdf

Protocols and Signalling Analysis HUAWEI UMTS Radio Access Network Table of Contents

Huawei Technologies Proprietary

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Table of Contents

Chapter 1 UTRAN Interface Protocols and Functions............................................................... 1-1 1.1 Overview ............................................................................................................................ 1-1 1.2 Uu Interface ....................................................................................................................... 1-2

1.2.1 Uu Protocol Structure.............................................................................................. 1-2 1.2.2 RRC Functions........................................................................................................ 1-4 1.2.3 L2 Functions............................................................................................................ 1-5 1.2.4 L1 Functions............................................................................................................ 1-6

1.3 Iub Interface....................................................................................................................... 1-6 1.3.1 Iub Protocol Structure ............................................................................................. 1-6 1.3.2 NBAP Functions...................................................................................................... 1-7 1.3.3 NBAP Procedures ................................................................................................... 1-9 1.3.4 Iub FP for Common Transport Channel Data Transfer......................................... 1-10 1.3.5 Iub FP for Dedicated Transport Channel Data Transfer ....................................... 1-14

1.4 Iur Interface...................................................................................................................... 1-18 1.4.1 Iur Protocol Structure ............................................................................................ 1-18 1.4.2 RNSAP Functions ................................................................................................. 1-19 1.4.3 RNSAP Procedures .............................................................................................. 1-20 1.4.4 Iur FP for Transport Channel Data Transfer ......................................................... 1-22

1.5 Iu Interface ....................................................................................................................... 1-22 1.5.1 Iu Protocol Structure ............................................................................................. 1-22 1.5.2 RANAP Functions ................................................................................................. 1-25 1.5.3 RANAP Procedures .............................................................................................. 1-27 1.5.4 Iu UP Functions..................................................................................................... 1-29 1.5.5 GTP-U Functions................................................................................................... 1-34 1.5.6 SABP Functions .................................................................................................... 1-34

Protocols and Signalling Analysis HUAWEI UMTS Radio Access Network

Chapter 1 UTRAN Interface Protocols and Functions


1-1

Chapter 1 UTRAN Interface Protocols and

Functions

1.1 Overview

Figure 1-1 UTRAN interfaces

As shown in Figure 1-1, UTRAN interfaces in the UMTS system include Iub, Iur, Iu and Uu interfaces. See Table 1-1 for the description of the interfaces.

Table 1-1 UTRAN interfaces

Interface Description

Uu Logical interface between UTRAN and UE

Iub Logical interface between RNC and NodeB

Iur Logical interface between RNCs

Iu Logical interface between RNC and CN




1-2

Iub, Iur, Iu and Uu interfaces are standard interfaces and can be used to connect different network elements (NEs) from different providers. Iub, Iur and Iu interfaces are also called UTRAN terrestrial interfaces.

According to the type of CN entity connected to RNC, the Iu interface can be classified as Iu-CS interface, Iu-PS interface and Iu-BC interface. The Iu-CS interface is used to connect RNC and MSC. The Iu-PS interface is used to connect RNC and SGSN. The Iu-BC interface is used to connect RNC and CBC.

1.2 Uu Interface

1.2.1 Uu Protocol Structure

Uu interface is the interface between User Equipment (UE) and UMTS Terrestrial Radio Access Network (UTRAN) and it is the most important interface in the UMTS system.

As shown in Figure 1-2, the Uu interface includes three protocol layers, physical layer (L1), data link layer (L2) and network layer (L3).

L1 provides the radio physical channels for the transmission of the traffic from upper layers. The functions of L1 are implemented by NodeB.

L2 includes four sublayers, Medium Access Control (MAC), Radio Link Control (RLC), Broadcast/Multicast Control (BMC) and Packet Data Convergence Protocol (PDCP). The functions of L2 are implemented by RNC.

L3 includes the Radio Resource Control (RRC) sublayer in the access stratum, the Mobility Management (MM) and Call Control (CC) in the non-access stratum (NAS). The RRC functions of L3 are implemented by RNC, and the MM and CC functions of L3 are implemented by CN.




1-3

L3

co

ntr

co

ntr

co

ntr

co

ntr

LogicalChannels

TransportChannels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DCNtGC

L2/RLC

MAC

RLCRLC

RLCRLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNtGC

RadioBearers

RRC

Figure 1-2 Uu interface protocol stack

The technical specifications of Uu interface are shown in Figure 1-3.




1-4

L3

cont

rol

cont

rol

cont

rol

cont

rol

LogicalChannels

TransportChannels

C-plane signalling U-plane information

TS25.211~TS25.215

L2/MAC

L1

RLC

DCNtGC

L2/RLC

TS25.321

RLCRLC

RLCRLC

RLCRLCTS25.322

Duplication avoidance

UuS boundary

TS25.324 L2/BMC

TS25.331

control

TS25.323 L2/PDCP

DCNtGC

Figure 1-3 Uu interface technical specifications

1.2.2 RRC Functions

The RRC performs the functions listed below:

Broadcast of information related to the non-access stratum (Core Network) Broadcast of information related to the access stratum Establishment, maintenance and release of an RRC connection between the UE

and UTRAN Establishment, reconfiguration and release of Radio Bearers Assignment, reconfiguration and release of radio resources for the RRC

connection RRC connection mobility functions Route selection for the Protocol Data Unit (PDU) of upper layers Control of requested QoS UE measurement reporting and control of the reporting Outer loop power control Control of ciphering Paging Initial cell selection and cell re-selection




1-5

Arbitration of radio resources on uplink DCH RRC message integrity protection CBS control

1.2.3 L2 Functions

L2 includes four sublayers, Medium Access Control (MAC), Radio Link Control (RLC), Broadcast/Multicast Control (BMC) and Packet Data Convergence Protocol (PDCP).

I. MAC

The functions of MAC include:

Mapping between logical channels and transport channels Selection of appropriate transport format for each transport channel Priority handling between data flows of one UE Priority handling between UEs by means of dynamic scheduling Priority handling between data flows of several UEs on FACH Identification of UEs on common transport channels Multiplexing/demultiplexing of upper layer PDUs into/from transport blocks

delivered to/from the physical layer on common transport channels Traffic volume measurement Transport channel type switching Ciphering for transparent mode RLC Access Service Class selection

II. RLC

The functions of RLC include:

Segmentation, reassembly, concatenation, padding and transfer of user data Flow control Error correction, in-sequence delivery of upper layer PDUs and duplicate

detection Sequence numbers check Protocol error detection and recovery Ciphering Suspend/resume function

III. PDCP

The functions of PDCP include:

Header compression and decompression of IP data streams at the transmit and receive entities respectively

Transfer of user data




1-6

Forwarding of PDCP-SDUs from NAS to RLC, and multiplexing of different RBs to the same RLC entity

IV. BMC

The functions of BMC include:

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)

1.2.4 L1 Functions

The functions of L1 (physical layer) mainly includes:

Provision for higher layers with measurements and indications (such as FER, SIR, interference power, and transmission power)

Macro-diversity distribution/combination and soft handover execution Frequency and time (chip, bit, slot, frame) synchronization Closed-loop power control RF processing Multiplexing of transport channels and demultiplexing of coded composite

transport channels Mapping of coded composite transport channels onto physical channels Modulation/demodulation and spreading/despreading of physical channels

The detailed functions and relevant specifications of L1 are involved with the basic principles of WCMDA. They are out of the range of this manual. Refer to relevant protocols and documents for details.

1.3 Iub Interface

1.3.1 Iub Protocol Structure

Iub interface is the interface between RNC and NodeB. The protocol stack of Iub interface is illustrated in Figure 1-4.




1-7

Node BApplication Part (NBAP)

TransportLayer

ATM

Physical Layer

Radio NetworkControl Plane

User Plane

Transport Network Control Plane

RadioNetwork

Layer

Q.2630.1

Q.2150.2

ALCAP

SSCF-UNI

SSCOP

AAL Type 5

SSCF-UNI

SSCOP

AAL Type 5 AAL Type 2

PC

H FP

FAC

H FP

RA

CH

FPD

CH

FP

Figure 1-4 Iub interface protocol stack

The technical specifications of Iub interface are shown in Figure 1-5.

NBAPTS 25.433

Transport Layer

Physical Layer TS 25.431

Radio Network Layer


TransportNetwork

Control Plane

NBAP Transport

TS 25.432

User Plane

DedicatedChannels

TS 25.427

CommonChannels

TS 25.435

DedicatedChannel

Transport

TS 25.426

CommonChannel

Transport

TS 25.434

Transport Signaling

TS 25.426(Dedicated ChannelTransport)

TS 25.434(Common ChannelTransport)

Figure 1-5 Iub interface technical specifications

1.3.2 NBAP Functions

NodeB Application Part (NBAP) is the signalling protocol of the control plane of the radio network layer on the Iub interface, which provides the following functions:

Cell Configuration Management




1-8

This function gives the controlling RNC (CRNC) the possibility to manage the cell configuration information in a NodeB.

Common Transport Channel Management

This function gives the CRNC the possibility to manage the configuration of common transport channels in a NodeB.

System Information Management

This function gives the CRNC the ability to manage the scheduling of System Information to be broadcast in a cell.

Resource Event Management

This function gives the NodeB the ability to inform the CRNC about the status of NodeB resources.

Configuration Alignment

This function gives the CRNC and the NodeB the possibility to verify and enforce that both nodes have the same information on the configuration of the radio resources.

Measurements on Common Resources

This function allows the NodeB to initiate measurements in the NodeB. The function also allows the NodeB to report the result of the measurements.

Radio Link Management

This function allows the CRNC to manage radio links using dedicated resources in a NodeB.

Radio Link Supervision

This function allows the CRNC to report failures and restorations of a radio link.

Compressed Mode Control

This function allows the CRNC to control the usage of compressed mode in a NodeB.

Measurements on Dedicated Resources

This function allows the CRNC to initiate measurements in the NodeB. The function also allows the NodeB to report the result of the measurements.

DL Power Drifting Correction

This function allows the CRNC to adjust the DL power level of one or more radio links in order to avoid DL power drifting between radio links.

Reporting of General Error Situations

This function allows reporting of general error situations.




1-9

1.3.3 NBAP Procedures

NBAP procedures are divided into common procedures and dedicated procedures.

NBAP common procedures are procedures that request initiation of a UE context for a specific UE in NodeB or are not related to a specific UE. NBAP common procedures also incorporate logical O&M procedures.

NBAP dedicated procedures are procedures that are related to a specific UE context in NodeB. This UE context is identified by a UE context identity.

The two types of procedures may be carried on separate signalling links.

I. NBAP Common Procedures

The NBAP functions and corresponding NBAP elementary procedures (EPs) are shown in the Table 1-2.

Table 1-2 NBAP functions and corresponding elementary procedures

Function Elementary procedure

Cell Configuration Management Cell Setup Cell Reconfiguration Cell Deletion

Common Transport Channel Management

Common Transport Channel Setup Common Transport Channel Reconfiguration Common Transport Channel Deletion

System Information Management System Information Update

Resource Event Management Block Resource Unblock Resource Resource Status Indication

Configuration Alignment Audit Required Audit

Reset

Measurements on Common Resources

Common Measurement Initiation Common Measurement Reporting Common Measurement Termination Common Measurement Failure

Radio Link Management. Radio Link Setup

II. NBAP Dedicated Procedures

The NBAP functions and corresponding NBAP dedicated procedures are shown in Table 1-3.




1-10

Table 1-3 NBAP functions and corresponding dedicated procedures

Function Dedicated procedure

Radio Link Management. Radio Link Addition Radio Link Deletion Unsynchronized Radio Link Reconfiguration Synchronized Radio Link Reconfiguration Preparation Synchronized Radio Link Reconfiguration Commit Synchronized Radio Link Reconfiguration Cancellation

Radio Link Pre-emption

Radio Link Supervision. Radio Link Failure Radio Link Restoration

Compressed Mode Control Radio Link Setup Radio Link Addition Compressed Mode Command Unsynchronized Radio Link Reconfiguration Synchronized Radio Link Reconfiguration Preparation Synchronized Radio Link Reconfiguration Commit Synchronized Radio Link Reconfiguration Cancellation


Dedicated Measurement Initiation Dedicated Measurement Reporting Dedicated Measurement Termination Dedicated Measurement Failure

DL Power Drifting Correction Downlink Power Control


Error Indication

1.3.4 Iub FP for Common Transport Channel Data Transfer

Iub frame protocol (FP) for common transport channel data transfer is the protocol of the user plane of the radio network layer on the Iub interface, which provides the following services:

Transport of Transport Block Set (TBS) between the NodeB and the CRNC for common transport channels (including RACH, FACH, and PCH)

Support of transport channel synchronization mechanism Support of Node Synchronization mechanism




1-11

I. RACH Data Transfer

RACH Data Transfer procedure is to transfer RACH Data Frame from NodeB to CRNC, as shown in Figure 1-6.

RACH Data Frame

NodeB CRNC

Figure 1-6 RACH data transfer procedure

II. FACH Data Transfer

FACH Data Transfer procedure is to transfer FACH Data Frame from CRNC to NodeB, as shown in Figure 1-7.

FACH Data Frame

NodeB CRNC

Figure 1-7 FACH data transfer procedure

III. PCH Data Transfer

PCH Data Transfer procedure is to transfer PCH Data Frame from CRNC to NodeB, as shown in Figure 1-8.

PCH Data Frame

NodeB CRNC

Figure 1-8 PCH data transfer procedure




1-12

IV. Node Synchronization

Node synchronization is to obtain the round trip delay (RTD) of transmission over the Iub interface.

In the Node Synchronization procedure, the RNC sends a DL Node Synchronization control frame to the NodeB containing the parameter T1. Upon reception of the frame, the NodeB shall respond with a UL Node Synchronization control frame, indicating T2 and T3, as well as T1 that was indicated in the initiating DL Node Synchronization control frame, as shown in Figure 1-9.

DL Node Synchronization

NodeB CRNC

UL Node Synchronization

Figure 1-9 Node synchronisation procedure

Parameters T1, T2, and T3 are defined as follows:

T1: RNC specific frame number (RFN) that indicates the time when the RNC sends the DL Node Synchronization control frame through the service access point (SAP) to the transport network layer.

T2: NodeB specific frame number (BFN) that indicates the time when the NodeB receives the correspondent DL Node Synchronization control frame through the SAP from the transport network layer.

T3: NodeB specific frame number (BFN) that indicates the time when the NodeB sends the UL Node Synchronization control frame through the SAP to the transport network layer.

V. DL Transport Channels Synchronization

DL transport channel synchronization procedure is used to synchronize the transport channel after the transport channel has been set up or used to maintain the synchronization of the transport channel when there is no DL data frame.

In the DL transport channel synchronization procedure, the CRNC sends a DL Synchronization control frame to the NodeB. This message indicates the target Connection Frame Number (CFN). Upon reception of the frame, the NodeB shall immediately respond with a UL Synchronization control frame indicating the Time of Arrival (ToA) for the DL Synchronization frame and the CFN indicated in the received message, as shown in Figure 1-10.




1-13

DL Synchronization

NodeB CRNC

UL Synchronization

Figure 1-10 FACH and PCH transport channels synchronization procedure

VI. DL Timing Adjustment

Timing Adjustment procedure is used for a NodeB to indicate the CRNC the incorrect ToA of downlink data to the NodeB.

Timing adjustment procedure is initiated by the NodeB if a DL frame arrives outside of the defined arrival window. If the DL frame has arrived before the ToAWS or after the ToAWE, the NodeB will include the ToA and the target CFN in the Timing Adjustment control frame, as shown in Figure 1-11.

Timing Adjustment

NodeB CRNC

.

Figure 1-11 FACH and PCH Timing Adjustment procedure

The arrival window and the ToA are defined as follows:

Time of Arrival Window Endpoint (ToAWE): ToAWE represents the time point by which the DL data shall arrive at the NodeB from Iub. ToAWE is defined as the amount of milliseconds before the last time point from which a timely DL transmission for the identified CFN would still be possible taking into account the NodeB internal delays. ToAWE is set via control plane. If data does not arrive before ToAWE, a Timing Adjustment control frame shall be sent by NodeB.

Time of Arrival Window Startpoint (ToAWS): ToAWS represents the time after which the DL data shall arrive at the NodeB from Iub. ToAWS is defined as the amount of milliseconds from ToAWE. ToAWS is set via control plane. If data arrives before ToAWS, a Timing Adjustment control frame shall be sent by NodeB.

Time of Arrival (ToA): ToA is the time difference between the end point of the DL arrival window (ToAWE) and the actual arrival time of DL frame for a specific CFN. A positive ToA means that the frame is received before ToAWE. A negative ToA means that the frame is received after ToAWE.




1-14

1.3.5 Iub FP for Dedicated Transport Channel Data Transfer

Iub FP for dedicated transport channel data transfer is the radio network user plane of Iub interface which provides the following services:

Transport of TBS between Serving RNC (SRNC) and NodeB Transport of outer loop power control information between SRNC and NodeB Support of transport channel synchronization mechanism Support of Node Synchronization mechanism Transfer of radio interface parameters from SRNC to NodeB

I. Uplink Data Transfer

UL Data Frame

NodeB SRNC

Figure 1-12 Uplink data transfer procedure

Uplink Data Transfer procedure is to transfer UL Data Frame from NodeB to SRNC, as shown in Figure 1-12.

Two modes can be used for the UL transmission: normal mode and silent mode. The SRNC selects the mode when setting up the transport bearer and notifies the NodeB with the relevant control plane procedure.

In normal mode, the NodeB shall always send an UL Data Frame to the RNC for all the DCHs in a set of coordinated DCHs regardless of the number of Transport Blocks of the DCHs.

In silent mode and in case only one transport channel is transported on a transport bearer, the NodeB shall not send an UL Data Frame to the RNC when it has received a TFI indicating “number of TB equal to 0” for the transport channel during a TTI.

In silent mode and in case of coordinated DCHs, when the NodeB receives a TFI indicating “number of TB equal to 0” for all the DCHs in a set of coordinated DCHs, the NodeB shall not send an UL data frame to the RNC for this set of coordinated DCHs.




1-15

II. Downlink Data Transfer

DL Data Frame

NodeB SRNC

Figure 1-13 Downlink data transfer procedure

Downlink Data Transfer procedure is to transfer DL Data Frame from SRNC to NodeB, as shown in Figure 1-13.

The NodeB shall consider a transport bearer synchronized only after it has received at least one data frame on this transport bearer before the latest time of arrival (LTOA).

The NodeB shall consider the DL user plane for a certain RL synchronized if all transport bearers established for carrying DL DCH data frames for this RL are synchronized.

Only when the DL user plane is considered synchronized, the NodeB shall transmit the data on the DL DPDCH.

When the DL user plane is considered synchronized and the NodeB does not receive a valid DL Data Frame in a TTI, it assumes that there is no data to be transmitted in that TTI for this transport channel, and shall act as one of the following cases:

If the NodeB is aware of a TFI value corresponding to zero bits for this transport channel, this TFI is assumed. When combining the TFI’s of the different transport channels, a valid TFCI might result and in this case data shall be transmitted on Uu.

If the NodeB is not aware of a TFI value corresponding to zero bits for this transport channel or if combining the TFI corresponding to zero bits with other TFI’s, results in an unknown TFI combination, the handling will be different. In the former case, at each radio frame, the NodeB shall build the TFCI value of each CCTrCH, according to the TFI of the DCH data frames multiplexed on this CCTrCH. In the latter case, the NodeB shall transmit only the DPCCH without TFCI bits.

III. Outer Loop Power Control Information Transfer

Outer loop power control information transfer procedure is to transfer Outer Loop PC control frame from SRNC to NodeB, as shown in Figure 1-14. The Outer Loop PC control frame can be sent via any of the transport bearers dedicated to one UE.




1-16

Based, for example, on the CRC Indicator (CRCI) values and on the quality estimate in the UL frames, the SRNC modifies the SIR target used by the UL Inner Loop Power Control by including the absolute value of the new SIR target in the Outer Loop PC control frame sent to the NodeB's. Upon reception of the Outer Loop PC control frame, the NodeB shall immediately update the SIR target used for the inner loop power control with the specified value.

Outer Loop PC

NodeB SRNC

Figure 1-14 Outer loop power control information transfer procedure

IV. Radio Interface Parameter Update

Radio interface parameter update procedure is used to update radio interface parameters which are applicable to all RL’s for the concerning UE. Both synchronized and unsynchronized parameter updates are also supported.

The procedure is realized by a transmission of Radio Interface Parameter Update control frame from SRNC to the NodeB, as shown in Figure 1-15.

Radio Interface Parameter Update

NodeB SRNC

Figure 1-15 Radio interface parameter update procedure

V. Node Synchronization

Node synchronization procedure is to obtain the round trip delay (RTD) of transmission over the Iub interface.

In the Node Synchronization procedure, the SRNC sends a DL Node Synchronization control frame to the NodeB containing the parameter T1. Upon reception of the frame, the NodeB shall respond with a UL Node Synchronization control frame, indicating T2 and T3, as well as T1 that was indicated in the initiating DL Node Synchronization control frame, as shown in Figure 1-16.




1-17

DL Node Synchronization

NodeB SRNC

UL Node Synchronization

Figure 1-16 Node synchronization procedure

Parameters T1, T2, and T3 are defined as:

T1: RNC specific frame number (RFN) that indicates the time when RNC sends the DL Node Synchronization control frame through the SAP to the transport network layer.

T2: NodeB specific frame number (BFN) that indicates the time when the NodeB receives the correspondent DL Node Synchronization control frame through the SAP from the transport network layer.

T3: NodeB specific frame number (BFN) that indicates the time when the NodeB sends the UL Node Synchronization control frame through the SAP to the transport network layer.

VI. DL Transport Channel Sychronization

DL transport channel synchronization procedure is used to achieve or restore the synchronization of the DCH data stream in DL direction, and as a keep-alive procedure in order to maintain activity on the Iur/Iub transport bearer.

In the DL transport channel synchronization procedure, the CRNC sends a DL Synchronization control frame to the NodeB. This message indicates the target Connection Frame Number (CFN). Upon reception of the frame, the NodeB shall immediately respond with a UL Synchronization control frame indicating the Time of Arrival (ToA) for the DL Synchronization frame and the CFN indicated in the received message, as shown in Figure 1-17.

The UL Synchronization control frame shall always be sent, even if the DL Synchronization control frame is received by the NodeB within the arrival window.

DL Synchronization

NodeB SRNC

UL Synchronization

Figure 1-17 DCH synchronization procedure




1-18

VII. DL Timing Adjustment

Timing adjustment procedure is used to keep the synchronization of the DCH data stream in DL direction.

The timing adjustment procedure is initiated by the NodeB if a DL frame arrives outside of the defined arrival window. If the DL frame has arrived before the ToAWS or after the ToAWE, NodeB will include the ToA and the target CFN in the Timing Adjustment control frame, as shown in Figure 1-18.

Timing Adjustment

NodeB SRNC

Figure 1-18 Timing adjustment procedure

1.4 Iur Interface

1.4.1 Iur Protocol Structure

Iur interface is the interface between RNCs. The protocol stack of Iur interface is illustrated in Figure 1-19.

Iur DataStream(s)

ALCAP(Q.2630.1)TransportNetwork

Layer

ATM

SSCOP

Physical Layer

SCCP

TransportUser

NetworkPlane

Control Plane User Plane

TransportUser

NetworkPlane

STC (Q.2150.1)

Transport NetworkControl Plane

RadioNetwork

Layer RNSAP

MTP3-B

SSCF-NNI

SSCOP

AAL5

MTP3-B

SSCF-NNI

AAL5 AAL2

Figure 1-19 Iur interface protocol stack




1-19

The technical specifications of the Iur interface are shown in Figure 1-20.

RNSAP

TS 25.423

TransportLayer

Physical Layer TS 25.421

RadioNetworkLayer


TransportNetwork

Control Plane

SignallingTransport

TS 25.422

User PlaneDedicatedChannels

TS 25.427

CommonChannels

TS 25.425

DedicatedChannel

Transport

TS 25.426

CommonChannel

Transport

TS 25.424

Transport Signaling

TS 25.426(Dedicated Channel

Transport)

TS 25.424(Common Channel

Transport)

Figure 1-20 Iur interface technical specifications

1.4.2 RNSAP Functions

Radio Network Subsystem Application Part (RNSAP) is the signalling protocol of the control plane of the radio network layer on Iur interface, which provides the following functions:

Radio Link Management

This function allows the Serving RNC (SRNC) to manage radio links using dedicated resources in a Drift RNS (DRNS).

Physical Channel Reconfiguration

This function allows the Drift RNC (DRNC) to reallocate the physical channel resources for a radio link.

Radio Link Supervision

This function allows the DRNC to report failures and restorations of a radio link.

Compressed Mode Control

This function allows the SRNC to control the usage of compressed mode within a DRNS.


This function allows the SRNC to initiate measurements on dedicated resources in the DRNS. The function also allows the DRNC to report the result of the measurements.

DL Power Drifting Correction




1-20

This function allows the SRNC to adjust the DL power level of one or more Radio Links in order to avoid DL power drifting between the radio links.

CCCH Signalling Transfer

This function allows the SRNC and DRNC to pass information between the UE and the SRNC on a CCCH controlled by the DRNS.

Paging

This function allows the SRNC to page a UE in a URA or a cell in the DRNS.

Relocation Execution

This function allows the SRNC to finalize a relocation previously prepared via other interfaces.


This function allows reporting of general error situations, for which function specific error messages have not been defined.

1.4.3 RNSAP Procedures

RNSAP procedures can be classified into class 1 and class2.

The procedures of class 1 have response messages including successful or unsuccessful outcome, as shown in Table 1-4.

The procedures of class 2 have no response message. The message is always assumed successful, as shown in Table 1-5.

Table 1-4 RNSAP class 1 elementary procedures

Response message Elementary procedure

Initiating message

Successful outcome

Unsuccessful outcome

Radio Link Setup

RADIO LINK SETUP REQUEST

RADIO LINK SETUP RESPONSE

RADIO LINK SETUP FAILURE

Radio Link Addition

RADIO LINK ADDITION REQUEST

RADIO LINK ADDITION RESPONSE

RADIO LINK ADDITION FAILURE

Radio Link Deletion

RADIO LINK DELETION REQUEST

RADIO LINK DELETION RESPONSE

Synchronised Radio Link Reconfiguration Preparation

RADIO LINK RECONFIGURATION PREPARE

RADIO LINK RECONFIGURATION READY

RADIO LINK RECONFIGURATION FAILURE




1-21


Initiating message

Successful outcome

Unsuccessful outcome

Unsynchronised Radio Link Reconfiguration

RADIO LINK RECONFIGURATION REQUEST

RADIO LINK RECONFIGURATION RESPONSE

RADIO LINK RECONFIGURATION FAILURE

Physical Channel Reconfiguration

PHYSICAL CHANNEL RECONFIGURATION REQUEST

PHYSICAL CHANNEL RECONFIGURATION COMMAND

PHYSICAL CHANNEL RECONFIGURATION FAILURE

Dedicated Measurement Initiation

DEDICATED MEASUREMENT INITIATION REQUEST

DEDICATED MEASUREMENT INITIATION RESPONSE

DEDICATED MEASUREMENT INITIATION FAILURE

Common Transport Channel Resources Initialisation

COMMON TRANSPORT CHANNEL RESOURCES REQUEST

COMMON TRANSPORT CHANNEL RESOURCES RESPONSE

COMMON TRANSPORT CHANNEL RESOURCES FAILURE

Table 1-5 RNSAP class 2 elementary procedures

Elementary procedure Initiating message

Uplink Signalling Transfer UPLINK SIGNALLING TRANSFER INDICATION

Downlink Signalling Transfer DOWNLINK SIGNALLING TRANSFER REQUEST

Relocation Commit RELOCATION COMMIT

Paging PAGING REQUEST

Synchronised Radio Link Reconfiguration Commit

RADIO LINK RECONFIGURATION COMMIT

Synchronised Radio Link Reconfiguration Cancellation

RADIO LINK RECONFIGURATION CANCEL

Radio Link Failure RADIO LINK FAILURE INDICATION

Radio Link Restoration RADIO LINK RESTORE INDICATION

Dedicated Measurement Reporting

DEDICATED MEASUREMENT REPORT

Dedicated Measurement Termination

DEDICATED MEASUREMENT TERMINATION REQUEST

Dedicated Measurement Failure DEDICATED MEASUREMENT FAILURE INDICATION


Chapter 1UTRAN Interface Protocols and Functions


1-22

Elementary procedure Initiating message

Downlink Power Control DL POWER CONTROL REQUEST

Compressed Mode Command COMPRESSED MODE COMMAND

Common Transport Channel Resources Release

COMMON TRANSPORT CHANNEL RESOURCES RELEASE REQUEST

Error Indication ERROR INDICATION

Radio Link Pre-emption RADIO LINK PREEMPTION REQUIRED INDICATION

1.4.4 Iur FP for Transport Channel Data Transfer

Iur frame protocol (FP) is the protocol of the user plane of the radio network layer on the Iur interface. It includes Iur FP for common transport channel data transfer and Iur FP for dedicated transport channel data transfer.

Iur FP for common transport channel data transfer and Iub FP for common transport channel data transfer are both specified in 3GPP TS25.425 protocol. For details, refer to section 1.3.4 “Iub FP for Common Transport Channel Data Transfer”.

Iur FP for dedicated transport channel data transfer and Iub FP for dedicated transport channel data transfer are both specified in 3GPP TS25.427 protocol. For details, refer to section 1.3.5 “Iub FP for Dedicated Transport Channel Data Transfer”.

1.5 Iu Interface

1.5.1 Iu Protocol Structure

Iu interface is the interface between UTRAN and CN.

The Iu interface between UTRAN and CS domain of CN is called Iu-CS. The protocol stack is shown in Figure 1-21.

The Iu interface between UTRAN and PS domain of CN is called Iu-PS. The protocol stack is shown in Figure 1-22.

The Iu interface between UTRAN and BC domain of CN is called Iu-BC. The protocol stack is shown in Figure 1-23.




1-23

Iu UP Protocol Layer

Q.2630.1TransportNetwork

Layer

ATM

SSCOP

Physical Layer

SCCP

TransportUser

NetworkPlane


TransportUser

NetworkPlane

Q.2150.1


RadioNetwork

Layer RANAP

MTP3-B

SSCF-NNI

SSCOP

AAL5

MTP3-B

SSCF-NNI

AAL5 AAL2

Figure 1-21 Iu-CS interface protocol stack

Iu UP Protocol Layer

TransportNetwork

Layer

ATM

SSCOP

Physical Layer

SCCP

TransportUser

NetworkPlane


TransportUser

NetworkPlane


RadioNetwork

Layer RANAP

MTP3-B

AAL5 AAL5

ATM

Physical Layer

IP

GTP-UUDPSSCF-NNI

Figure 1-22 Iu-PS interface protocol stack




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TransportNetwork

Layer

RadioNetwork

Layer SABP Protocol Layer

SA Broadcast Plane

TransportUser

NetworkPlane

AAL5

IP

TCP

Physical Layer

ATM

Figure 1-23 Iu-BC interface protocol stack

The technical specifications of Iu interface are shown in Figure 1-24.




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25.413 25.415

TransportNetwork

Layer

25.411

TransportUser

NetworkPlane


TransportUser

NetworkPlane


RadioNetwork

Layer

25.412 25.414

25.419

SA Broadcast Plane

TransportUser

NetworkPlane

Figure 1-24 Iu interface technical specifications

1.5.2 RANAP Functions

Radio Access Network Application Part (RANAP) is the signalling protocol of the control plane of the radio network layer on the Iu interface, which provides the following functions:

Relocating SRNC

This function enables to change the SRNC functionality as well as the related Iu resources (RAB(s) and Signalling connection) from one RNC to another.

Overall RAB management

This function is responsible for setting up, modifying and releasing RABs.

Queuing the setup of RAB

The purpose of this function is to allow placing some requested RABs into a queue, and indicate the peer entity about the queuing.

Requesting RAB release

While the overall RAB management is a function of the CN, the RNC has the capability to request the release of RAB.

Release of all Iu connection resources

This function is used to explicitly release all resources related to one Iu connection.




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Requesting the release of all Iu connection resources

While the Iu release is managed from the CN, the RNC has the capability to request the release of all Iu connection resources from the corresponding Iu connection.

SRNS context forwarding function

This function is responsible for transferring SRNS context from the RNC to the CN for intersystem forward handover in case of packet forwarding.

Controlling overload in the Iu interface

This function allows adjusting the load in the Iu interface.

Resetting the Iu

This function is used for resetting an Iu interface.

Sending the UE Common ID (permanent NAS UE identity) to the RNC

This function makes the RNC aware of the UE's Common ID.

Paging the user

This function provides the CN for capability to page the UE.

Controlling the tracing of the UE activity

This function allows setting the trace mode for a given UE. This function also allows the deactivation of a previously established trace.

Transport of NAS information between UE and CN

This function has two sub-classes:

Sub-class1: Transport of the initial NAS signalling message from the UE to CN. This function transfers transparently the NAS information. After transmission, the Iu signalling connection is set up.

Sub-class2: Transport of NAS signalling messages between UE and CN, This function transfers transparently the NAS signalling messages on the existing Iu signalling connection. It also includes a specific service to handle signalling messages differently.

Controlling the security mode in the UTRAN

This function is used to send the security keys (ciphering and integrity protection) to the UTRAN, and setting the operation mode for security functions.

Controlling location reporting

This function allows the CN to operate the mode in which the UTRAN reports the location of the UE.

Location reporting

This function is used for transferring the actual location information from RNC to the CN.




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Data volume reporting function

This function is responsible for reporting unsuccessfully transmitted DL data volume over UTRAN for specific RABs.

Reporting general error situations

1.5.3 RANAP Procedures

RANAP procedures can be classified as class 1, class 2 and class 3.

The procedures of class 1 have response messages including successful or unsuccessful outcome, as shown in Table 1-6.

The procedures of class 2 have no response message. The message is always considered successful, as shown in Table 1-7.

The procedures of class 3 may have one or several response messages reporting both successful and unsuccessful outcomes of the requests as well as temporary status information about the requests, as shown in Table 1-8. This type of procedures only terminates through response(s) or EP timer expiry.

Table 1-6 NANAP class 1 elementary procedures


Initiating message

Successful outcome Unsuccessful outcome

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

RELOCATION 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




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Initiating message

Successful outcome Unsuccessful outcome

Reset RESET RESET ACKNOWLEDGE

Reset Resource

RESET RESOURCE

RESET RESOURCE ACKNOWLEDGE


Elementary procedure Message

RAB Release Request RAB 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 Indication ERROR INDICATION


Elementary procedure Initiating message Response message

RAB Assignment RAB ASSIGNMENT REQUEST RAB ASSIGNMENT RESPONSE x N (N>=1)




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1.5.4 Iu UP Functions

Iu UP is located in the user plane of the radio network layer on the Iu interface and used to convey user data associated to Radio Access Bearers (RABs). One Iu UP protocol instance is associated to one RAB only.

Iu UP protocol instances exist at Iu access point i.e. at CN and UTRAN. Whenever a RAB requires transfer of user data in the Iu UP, an Iu UP protocol instance exists at each Iu interface access points. These Iu UP protocol instances are established, relocated and released together with the associated RAB procedures.

The Iu UP includes two modes of operation: Transparent Mode (TrM) and Support Mode for predefined SDU size (SMpSDU).

Transparent mode (TrM)

The transparent mode is intended for those RABs that do not require any particular feature from the Iu UP protocol other than transfer of user data. Figure 1-25 illustrates the transparent mode of Iu UP protocol layer.

Iu UP layer(transparent mode)

TNL-SAP

RNL-SAP

TNL-SAP

CNUTRAN

R

adio

Inte

rface

P

roto

cols

Non AccessStratum

Access Stratum

Iu

Iu UP layer(transparent mode)

Figure 1-25 Transparent mode of Iu UP

In this mode, the Iu UP protocol instance does not perform any Iu UP protocol information exchange with its peer over the Iu interface. The Iu UP protocol layer is used for PDUs transfer between upper layers and transport network layer. For instance, Iu UP of Iu-PS adopts transparent mode.

Support mode

The support modes are intended for those RABs that require particular features from the Iu UP protocol in addition to transfer of user data. When operating in a support mode, the peer Iu UP protocol instances exchange Iu UP frames. Figure 1-26 illustrates the support mode of Iu UP protocol layer.




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TNL-SAP

Iu

TNL-SAP

Iu UP layer(support mode)

CNUTRAN

Rad

io In

terfa

ceP

roto

cols

RNL-SAPNon Access

Stratum

Access Stratum

Transfer of IuUP protocol

frames

Support ModeFunctions

Iu UP layer(support mode)

Support ModeFunctions

Figure 1-26 Support mode of Iu UP

The only support mode which has been defined is the support mode for predefined SDU size (SMpSDU). For instance, the transfer of AMR speech PDUs would utilize SMpSDU.

I. User Data Transfer

User data transfer procedure is to transfer Iu UP frames between the two Iu UP protocol layers on the Iu interface. Since an Iu UP instance is associated to an RAB and an RAB only, the user data being transferred only relate to the associated RAB.

As shown in Figure 1-27, the transfer of user data procedure is invoked whenever user data for that particular RAB needs to be sent across the Iu interface.

In SRNC, the upper layers may deliver frame quality classification information together with the RFCI.

CN/ RNC

RNC/ CN Transfer of User Data

(RFCI, payload)

Figure 1-27 Transfers of user data




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II. Initialization Procedure

Initialization procedure is to configure both termination points of the Iu UP with the RFCIs and associated RAB Sub Flows SDU sizes necessary during the transfer of user data phase. This procedure is mandatory for RABs using the support mode for predefined SDU size.

The RNC sends initialization frame to the CN, indicating the RFCIs and their corresponding RAB sub-flow SDU size, as shown in Figure 1-28.

If the CN receives the initialization frame and accepts the parameters, it will respond with an Initialization ACK frame. Otherwise, it will respond with an Initialization NACK frame.

*

Transfer Of User Data

Initialisation

((RFCI, SDU sizes ) m )

Initialisation ACK

* it can repeated n times

RNC CN/other

Figure 1-28 Initialization of Iu UP for m RFCIs

III. Iu Rate Control

Iu rate control procedure is to signal to the peer Iu UP protocol layer the permitted rate(s) over Iu in the reverse direction of the sent rate control frame.

The Iu rate control procedure is invoked whenever the SRNC/CN decides that the set of downlink/uplink permitted rates over Iu shall be modified, as shown in Figure 1-29. The permitted rate is given as RFCI indicators.

Rate Control(RFCI indicators,

[Downlink send intervals*])

* Optional

RNC/CN CN/RNC

Figure 1-29 Rate control




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IV. Time Alignment Procedure

Time alignment procedure is to minimize the buffer delay in RNC by controlling the transmission timing in the peer Iu UP protocol layer entity.

The time alignment procedure is invoked whenever the SRNC detects the reception of Iu UP PDU at an inappropriate timing that leads to an unnecessary buffer delay as shown in Figure 1-30. The Iu UP protocol layer entity in SRNC indicates the peer entity the necessary amount of the delay or advance adjustment in the number of 500 µs steps.

A supervision timer TTA is started after sending the Iu UP time alignment frame. This timer supervises the reception of the time alignment acknowledgement frame.

The requested Iu UP protocol layer entity in the peer node adjusts the transmission timing by the amount as indicated by SRNC. If the time alignment frame is correctly formatted and treated by the receiving Iu UP protocol layer and the time alignment is treated correctly by the upper layers, this latter sends a time alignment acknowledgement frame.

Upon reception of a time alignment acknowledgement frame, the Iu UP protocol layer in the SRNC stops the supervision timer TTA.

If the CN cannot handle the time alignment frame, it will send an NACK frame to the RNC, indicating the causes. The RNC will decide whether to send again the time alignment frame or not according to the causes and meanwhile stop the timer TTA.

Time Alignment

ACK

User data with bad timing

User data with adjusted timing

RNC CN

Figure 1-30 Time alignment

V. Error Event

Error event procedure is to handle the error reporting.




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Over the Iu UP protocol the error reports are made with Error event frames as shown in in Figure 1-31,The Error event procedure in the Iu UP can be triggered by:

An error detected by the Iu UP functions A request by the upper layers

When an Error event is reported by an Error event frame the following information shall be included:

A cause value Error distance (0: if Iu UP function detected; 1: if requested by upper layers).

CN or other/RNC

RNC/CN or other

Error event(Cause value,

Error distance)

Figure 1-31 Error event

VI. Frame Quality Classification

Frame quality classification (FQC) is used to classify the Iu UP frames depending on whether errors have occurred in the frame or not.

The FQC information is exchanged between RNC and CN through user data transfer procedure, as shown in Figure 1-32.

Transfer of User Data(FQC, RFCI, payload )

Transfer of User Data(FQC, RFCI, payload )

CN/RNCRNC/CN

Figure 1-32 Transfers of user data with FQC information




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1.5.5 GTP-U Functions

GPRS Tunnel Protocol User Plane (GTP-U) is to transfer Iu-PS user data through tunnel protocol. In addition, it also includes the user plane auxiliary signalling such as error indication of data transferring, handshaking message and supported extension head list.

1.5.6 SABP Functions

Service Area Broadcast Protocol (SABP) is the protocol of the radio network layer on the Iu-BC interface, which provides the following functions:

Message Handling

This function is to broadcast new messages, amend existing broadcasted messages, and stop the broadcasting of specific messages.

Load Handling

This function is responsible for determining the loading of the broadcast channels at any particular point in time.

Reset

This function permits the CBC to end broadcasting in one or more service areas.

Error Handling

This function allows the reporting of general error situations, for which function specific error messages have not been defined.

01-Chapter 1 UTRAN Interface Protocols and Functions.pdf

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