UMTS Interface Protocol

Content:

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

Terminology of UMTS RNS Network

n UTRAN: UMTS Terrestrial Radio Access Network

n RNS: Radio Network Subsystem

n RNC: Radio Network Controller

n UE: User Equipment

n Uu: Radio Interface

n Iub: The interface between NodeB and RNC

n Iur: The interface between RNCs

n Iu_CS: between RNC and CS domain

n Iu_PS:between RNC and PS domain

n Iu_BC:for BroadCast domain

Universal model of the UTRAN interfaces

n Horizontal: UTRAN falls into 2 layers

lRadio Network Layer (RNL)

lTransport Network Layer (TNL)

n Vertical:  UTRAN falls into 4 planes

l Control plane

l User plane

l TNL control plane

l TNL user plane

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

Iu interface Functions

n RAB management

lRAB setup, modification and release

lmapping of RAB characteristics to the Uu bearer

lmapping of RAB characteristics to the Iu transmission bearer

lRAB queuing, preemption and priority

n Iu radio resource management

lradio resource acceptance control

n Iu connection management

lIu signaling connection management

n Iu-UP (RNL) management

lIu-UP frame protocol mode selection and protocol initialization

n Mobility management

n Security management

n Service and network access

n Paging coordination

Stream Control Transmission Protocol(SCTP)

n SCTP is a reliable datagram transfer protocol based on an unreliable transfer protocol such as UDP.

n SCTP End Point is a logical entity, logical datagram sender and receiver. Each SCTP End Point is only identified by IP address and port number, similar to TCP.

n SCTP Association is a logical association or channel established between two SCTP End Points. Client/Server mode is adopted. 

MTP3-User Adaptation Layer Protocol(M3UA)

n M3UA (MTP3-User Adaptation Layer) protocol conducts conversion between SPCs and IP addresses. It is used for the SS7 signaling to transfer between the Softswitch and the Signaling Gateway(SG). It supports to transfer the MTP3 user messages over the IP network, including ISUP, TUP, and SCCP messages. 

Signaling connection control protocol SCCP

n RNC, SCCP protocol is mainly used to transport signaling message by Iu/Iur interface. The client is RANAP and RNSAP.

n It offers the connectionless or connection-oriented services for its client. The SCCP also offers the segmentation and reassembly functions.

Iur interface Functions

n Iur interface has the following functions:

n Inter-RNC mobility management

lSRNC relocation, inter-RNC cell and UTRAN registration area update, inter-RNC paging, and protocol error report.

n Dedicated channel data transmission

lused to transmit dedicated channel data between two RNCs.

n Common channel data transmission

lsetup and release of the transmission connection needed in common channel data stream transmission of the Iur interface,

n Global resource management

ltransmission of inter-RNC cell measurement information.

ltransmission of inter-RNC Node B timing information.

Iur Flow Overview

n Radio Link Management

n Physical Channel Reconfiguration

n Radio Link Supervision

n Compressed Mode Control

n Measurements on Dedicated Resources

n DL Power Drifting Correction

n CCCH Signaling Transfer

n Paging

n Common Transport Channel Resources Management

n Relocation Execution

Iub Interface Stack Structure

Iub interface Functions

n Management of the Iub interface transmission resources.

n Logic operation maintenance of Node B, including:

lthe cell configuration management

lradio network performance measurement

lcommon transmission channel management

lradio resource management

n Transmission of application-related operation & maintenance data.

n System information management.

n Channel traffic management.

n Timing and synchronization management, including:

lnode synchronization

ltransmission channel synchronization between the RNC and Node B

Iub Flow Overview

n Click to edit master text style

n System Information Management

n Configuration Alignment

n Measurements

n Radio Link Management

n Radio Link Supervision

n Compressed Mode Control

n DL Power Drifting Correction

Uu Interface Stack Structure

Uu Interface Stack Structure

n Physical Layer Protocol

lprovides the MAC sublayer with transmission channel services.

n MAC Protocol (Media Access Control)

lprovides the RLC sublayer with logic channel services.

n RLC Protocol (Radio Link Control)

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

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

n PDCP (Packet data convergence protocol)

ladapt different types of network layer protocols to the radio interface.

lonly exists in the packet domain

n BMC (Broadcast main control)

ltransfer broadcast and multicast information over the radio interface.

n RRC (Radio resource control)

lProvide services for the non-access layer, for example, transmitting messages like call control, session management and mobility management at the control interface.

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

lSetup, reconfiguration and release of radio bearer.

lDistribution, reconfiguration and release of radio resources used in the RRC connection.

lRRC connection’s mobility function management.

lRequest for QoS control.

lUE measurement report and report control.

lOuter loop power control, ciphering control, paging.

lInitial cell selection and reselection in the idle mode.

PDCP Function

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

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

n 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 services

BMC Services and Function

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

n 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.

BMC Sub-layer Structure

RLC Layer Work Modes

n 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.

n 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.

n 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-Some Transport Channel Principles

n Transport Block

lThe basic switching unit between L1 and MAC layer

n Transport Block Set

lA Set of Transport Blocks which are Transmitted in a Transport channel on a certain moment.

n Transport Block Size

lThe bit number of a Transport Block.

n Transport Block Set Size

lThe bit number of a Transport Block Set.

n Transport Time Interval

lTransport 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.

n Transport Format

lTransport 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.

MAC-Some Transport Channel Principles

n Transport Format Set

lTransport 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.

n Transport Format Combination

lWhen 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.

n Transport Format Combination Set

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

Combination of Coded Composite Transport Channel (CCTrCH) .

n Transport Format Indicator 

lTFI 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.

n Transport Format Combination Indicator

lTFCI is a indicator of the current Transport Format Combination.  

The Services Provided by L1 and Timing Operation

n The Physical Layer provides Data Transport Services for the upper layer, which are implemented by MAC sub-layer through Transport Channel.

lTransport 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.

n 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

n FEC encoding/decoding of transport channel

n To provide measurement and indicator for the upper layer (such as FER, SIR, 

Interference Power, Transport Power and so on)

n Macro Diversity distribution/ Combination and soft handover implementation

n Error Detection of transport channel

n Transport Channel multiplexing, Coding Combination Transport Channel demultiplexing

n Rate Matching

n To map Coding Combination Transport Channel to physical channel

n Physical channel modulation/Frequency Spreading and Demodulation/Frequency De-spreading

n Frequency and Timing (Chip, Bit, Slot, Frame) synchronization

n Close loop power control

n Physical channel power weight and combination

n RF Processing

Radio Network Control-Plane protocol

Finish UMTS Interface Protocol Course!