UMTS Interface ProtocolContents

11 UTRAN System Architecture

11.1 UTRAN Architecture

11.2 Explanation Related to RNS

21.3 UTRAN Common Protocol model

72 UMTS Interface Hierarchy

72.1 Control Plane and User Plane

72.2 Access Layer and Non-access Layer

13 Interface and Protocol

13.1 Protocol Overview

13.1.1 RRC Connection Setup

23.1.2 Network Registration Process

43.1.3 Connection Release Process

63.2 Protocol Related to Interface Uu

63.2.1 Uu Interface protocol architecture

133.2.2 Status of RRC Protocol

143.2.3 Some Explanations

143.3 Protocol related to Interface Iu

143.3.1 IU interface architecture

153.3.2 Protocol Structure of Iu Interface

203.3.3 Some Explanations

223.3.4 RANAP Process

243.4 Protocol related to Interface Iur

243.4.1 Function and Structure of Interface Iur

253.4.2 DCH Frame Protocol of Interface Iur

253.4.3 RNSAP Process

273.5 Protocol Related to Interface Iub

283.5.1 Node B Logic Model

283.5.2 NBAP Process

1 UTRAN System Architecture1.1 UTRAN ArchitectureFigure 1 shows the overall architecture of UMTS UTRAN (UMTS Terrestrial Radio Access Network) system of 3GPP R4.

Figure 1 Overall UTRAN Architecture

The interface between CN and UTRAN is Interface Iu.

Inside UTRAN, the interface between RNC and Node B is Interface Iub.

Inside UTRAN, the interface between RNCs is Interface Iur.

In addition, the interface between UTRAN and UE is Interface Uu.

1.2 Explanation Related to RNS

RNS (Radio Network Subsystem): The general name for one RNC and all Nodes B it manages.

SRNC (Serving RNC): The RNS connecting with CN is called SRNS and the RNC of RNS is called SRNC.

DRNC (Drift RNC): In the case of soft handover of UMTS, UE can use several RNSs. Figure 2 shows the relation of SRNS and DRNS.Figure 2 SRNS and DRNS

Several links can exist inside one UE at the same time. The user data to access DRNS is sent to SRNS from DRNS via Interface Iur. DRNC wont process the data but transmit it between Interface Iub and Interface Iur transparently. One UE can access one or several DRNSs.

CRNC (Control RNC): When UE access one RNS, the RNC of the RNS is called CRNC. Therefore, in Figure 2, both SRNC and DRNC are CRNC. CRNC manages the resources of the whole cell. SRNC schedules data on user DCH and CRNC schedules data on CCH.

For Source RNC (S-RNC) and Target RNC (T-RNC), refer to Chapter of Interface Iu.

1.3 UTRAN Common Protocol model

Figure 3 shows the general protocol model for UTRAN Interfaces, and described in detail in the following subclauses. The structure is based on the principle that the layers and planes are logically independent of each other. Therefore, as and when required, the standardisation body can easily alter protocol stacks and planes to fit future requirements.Figure 3 UTRAN Common Protocol Model

Horizontal, The Protocol Structure consists of two main layers, Radio Network Layer, and Transport Network Layer. All UTRAN related issues are visible only in the Radio Network Layer, and the Transport Network Layer represents standard transport technology that is selected to be used for UTRAN, but without any UTRAN specific requirements.

Vertical, UTRAn falls into the following 4 planes: control plane , user plane , TNL control plane , TNL user plane.

Control planeThe Control Plane Includes the Application Protocol, i.e. RANAP, RNSAP or NBAP, and the Signalling Bearer for transporting the Application Protocol messages.

Among other things, the Application Protocol is used for setting up bearers for (i.e. Radio Access Bearer or Radio Link) in the Radio Network Layer. In the three plane structure the bearer parameters in the Application Protocol are not directly tied to the User Plane technology, but are rather general bearer parameters.

The Signalling Bearer for the Application Protocol may or may not be of the same type as the Signalling Protocol for the ALCAP. The Signalling Bearer is always set up by O&M actions. User planeThe User Plane Includes the Data Stream(s) and the Data Bearer(s) for the Data Stream(s). The Data Stream(s) is/are characterised by one or more frame protocols specified for that interface. TNL control planeThe Transport Network Control Plane does not include any Radio Network Layer information, and is completely in the Transport Layer. It includes the ALCAP protocol(s) that is/are needed to set up the transport bearers (Data Bearer) for the User Plane. It also includes the appropriate Signalling Bearer(s) needed for the ALCAP protocol(s).

The Transport Network Control Plane is a plane that acts between the Control Plane and the User Plane. The introduction of Transport Network Control Plane makes it possible for the Application Protocol in the Radio Network Control Plane to be completely independent of the technology selected for Data Bearer in the User Plane.

When Transport Network Control Plane is used, the transport bearers for the Data Bearer in the User Plane are set up in the following fashion. First there is a signalling transaction by the Application Protocol in the Control Plane, which triggers the set up of the Data Bearer by the ALCAP protocol that is specific for the User Plane technology.

The independence of Control Plane and User Plane assumes that ALCAP signalling transaction takes place. It should be noted that ALCAP might not be used for all types Data Bearers. If there is no ALCAP signalling transaction, the Transport Network Control Plane is not needed at all. This is the case when pre-configured Data Bearers are used.

It should also be noted that the ALCAP protocol(s) in the Transport Network Control Plane is/are not used for setting up the Signalling Bearer for the Application Protocol or for the ALCAP during real time operation.

The Signalling Bearer for the ALCAP may or may not be of the same type as the Signalling Bearer for the Application Protocol. The Signalling Bearer for ALCAP is always set up by O&M actions. TNL user plane

The Data Bearer(s) in the User Plane, and the Signalling Bearer(s) for Application Protocol, belong also to Transport Network User Plane. As described in the previous subclause, the Data Bearers in Transport Network User Plane are directly controlled by Transport Network Control Plane during real time operation, but the control actions required for setting up the Signalling Bearer(s) for Application Protocol are considered O&M actions.2 UMTS Interface Hierarchy2.1 Control Plane and User Plane

Purpose of the control plane:Control the radio access bearer and the connection between UE and the network;

Transmit messages of non-access layer transparently.

Purpose of user plane:Transmit the user data via the access network.

In UTRAN, each interface of RNL has user plane and control plane.

The control plane protocols of each interface on RNL include:

Interface Iu: RANAP

Interface Iur: RANSAP

Interface Iub: NBAP

Interface :Uu: RRC protocol

The user plane data and control plane data of all RNL belong to TNL user plane. TNL control plane protocol is ALCAP, belonging to SAAL (Signalling AAL) of ATM.

2.2 Access Layer and Non-access Layer

The concepts of access layer and non-access layer are related to the communication of UE and CN. The access layer bears the upper layer services via the SAP (Service Access Point), as shown in Figure 4.

Figure 4 Access Layer and Non-access Layer

Example for non-access layer:

In AMR voice telephone (the calling party), there are several UE-CN signaling, which are the control plane signaling of non-access layer. These signaling are encapsulated in RRC protocol first and then transmitted to RNC transparently. RNC decodes these signaling out of RRC messages, encapsulates into RANAP, and then transmits to CN transparently via RANAP.

UE(RNCCM Service Request

RNC(UEAuthentication Request

UE(RNCAuthentication Response

RNC(UECM Service Accept

UE(RNCSETUP

RNC(UECall Processing

RNC(UEAlerting

RNC(UEConnect

UE(RNCConnect Acknowledge

3 Interface and Protocol

3.1 Protocol Overview

Besides the process that UE searches for the net, UE registration fall into 3 phases:

RRC connection setup

Network registration

Connection release

3.1.1 RRC Connection Setup

Figure 5 shows the flow of RRC connection setup.

Figure 5 RRC Connection Setup

Detailed descriptions:

At the beginning, UE does not have dedicated channel resources, so it sends the message of RRC connection setup on CCCH (RACH).RNC allocates RNTI and available resources to UE, decides to allocate DCH to UE, and inform Node B to allocate DCH to UE with NBAP message of Radio Link Setup Request.Node B allocates resources to UE, starts to receive, and returns Radio Link Setup Response to RNC.At this time, there are no resources of the transmission network on Interface Iub, so ALCAP of SRNC sends the message of ERQ (Establish Request). This message contains AAL2 binding ID. This ID can help Node B to bind the data transmission bearer on Interface Iub and DCH, and sends the message of ECF (Establish Confirm) back to RNC.Node B and SRNC perform the frame synchronization via Downlink Synchronization and Uplink. Synchronization in DCH frame protocol, and then to perform the DL transmission.Although DCH resources on Interface Iub are ready, UE does not know it. Therefore, SRNC sends the message of RRC Connection Setup to UE on CCCH (FACH), and informs UE of related parameters.According to related parameters in RRC Connection Setup, UE configures the physical layer. Node B sets up DCH successfully and sends the message of RRC Connection Setup Complete back to SRNC on DCH.3.1.2 Network Registration Process

Figure 6 shows the flow of UE registration for CS domain.

Figure 6 UE Location Update

Detailed descriptions:

After RRC connection sets up, UE establishes DCH. UE needs to change information with CN (this is signaling interaction of non-access layer and readers of non-access layer signaling can refer to [3]), that is, to initiate the Location Update. This message is encapsulated in the RRC message of Initial Direct Transfer, which is sent to RNC by UE.

RRC of RNC receives the message of Initial Direct Transfer, decodes the high-layer messages from it, and sends to RANAP entity. RANAP entity will encapsulate the message of Location Update into Initial UE Message and sends it to CN through SCCP entity. At this time, there is no signaling connection between RNC and CN, so the message of Initial UE Message of RANAP is encapsulated into SCCP connection setup massage (CR) and sent to CN.

SCCP entity of CN receives the SCCP connection setup request. It returns SCCP connection setup message (CC) to RNC and sends the RANAP massage contained in CR messages to RANAP entity. RANAP entity decodes the message of Location Update of NAS layer and sends it to the related modules on NAS layer for processing.

After receiving the message of Location Update from UE, CN initiates the authentication. The signalling during the authentication process is transmitted transparently. RNC and Node B only transfer between UE and CN, but do not process messages. Messages of Authentication Request and Authentication Response are NAS messages, too. They are encapsulated into the message of Direct Transfer of RANAP and RRC.

After the authentication check on UE is passed, CN initiates the security mode process. It is to encrypt and protect the data and signaling of the air interface. Messages of security mode are not transmitted transparently and it needs RNC processing.

After the authentication check is passed and the security mode is initiated, CN sends the message of Location Update Accept to UE, informing that UE registration succeeds. This message is transmitted transparently.

3.1.3 Connection Release Process

Figure 7 shows the connection release process.

Figure 7 RRC Connection Release

Detailed descriptions:

After Location Update completes, CN initiates Iu release process.

SRNC sends the message of RRC connection release to RRC.

UE sends the message of RRC connection release back to RNC.

RNC informs Node B to delete RL and after deleting RL, Node B replies to RNC.

RNC informs CN that returns Iu release completes via RANAP.

CN initiates to release SCCP link and RNC returns the message of SCCP release confirmation.

RNC initiates to release the transmission resources on Interface Iub.

3.2 Protocol Related to Interface Uu3.2.1 Uu Interface protocol architecture

Figure 8 shows the architecture of Uu Interface protocol.

Figure 8 Structure of RRC Protocol

The Uu interface is layered into three protocol layers:

the physical layer (L1);

the data link layer (L2);

network layer (L3).

Layer 2 is split into following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Broadcast/Multicast Control (BMC). Layer 3 and RLC are divided into Control (C-) and User (U-) planes. PDCP and BMC exist in the U-plane only.

In the C-plane, Layer 3 is partitioned into sublayers where the lowest sublayer, denoted as Radio Resource Control (RRC), interfaces with layer 2 and terminates in the UTRAN. The next sublayer provides 'Duplication avoidance' functionality. It terminates in the CN but is part of the Access Stratum; it provides the Access Stratum Services to higher layers. The higher layer signalling such as Mobility Management (MM) and Call Control (CC) is assumed to belong to the non-access stratum..

The functions of RLC:

The RLC sublayer provides ARQ functionality closely coupled with the radio transmission technique used. There is no difference between RLC instances in C and U planes.The UTRAN can be requested by the CN to prevent all loss of data (i.e. independently of the handovers on the radio interface), as long as the Iu connection point is not modified. This is a basic requirement to be fulfilled by the UTRAN retransmission functionality as provided by the RLC sublayer.However, in case of the Iu connection point is changed (e.g. SRNS relocation, streamlining), the prevention of the loss of data may not be guaranteed autonomously by the UTRAN but relies on 'Duplication avoidance' functions in the CN.There are primarily two kinds of signalling messages transported over the radio interface - RRC generated signalling messages and NAS messages generated in the higher layers. On establishment of the signalling connection between the peer RRC entities three or four UM/AM signalling radio bearers may be set up. Two of these bearers are set up for transport of RRC generated signalling messages - one for transferring messages through an unacknowledged mode RLC entity and the other for transferring messages through an acknowledged mode RLC entity.The functions of MAC include:

Mapping between logical channels and transport channels. The MAC is responsible for mapping of logical channel(s) onto the appropriate transport channel(s). Selection of appropriate Transport Format for each Transport Channel depending on instantaneous source rate. Given the Transport Format Combination Set assigned by RRC, MAC selects the appropriate transport format within an assigned transport format set for each active transport channel depending on source rate. The control of transport formats ensures efficient use of transport channels.

Priority handling between data flows of one UE. When selecting between the Transport Format Combinations in the given Transport Format Combination Set, priorities of the data flows to be mapped onto the corresponding Transport Channels can be taken into account. Priorities are e.g. given by attributes of Radio Bearer services and RLC buffer status. The priority handling is achieved by selecting a Transport Format Combination for which high priority data is mapped onto L1 with a "high bit rate" Transport Format, at the same time letting lower priority data be mapped with a "low bit rate" (could be zero bit rate) Transport Format. Transport format selection may also take into account transmit power indication from Layer 1.

Priority handling between UEs by means of dynamic scheduling. In order to utilise the spectrum resources efficiently for bursty transfer, a dynamic scheduling function may be applied. MAC realises priority handling on common and shared transport channels. Note that for dedicated transport channels, the equivalent of the dynamic scheduling function is implicitly included as part of the reconfiguration function of the RRC sublayer.

Identification of UEs on common transport channels. When a particular UE is addressed on a common downlink channel, or when a UE is using the RACH, there is a need for inband identification of the UE. Since the MAC layer handles the access to, and multiplexing onto, the transport channels, the identification functionality is naturally also placed in MAC.

Multiplexing/demultiplexing of upper layer PDUs into/from transport blocks delivered to/from the physical layer on common transport channels. MAC should support service multiplexing for common transport channels, since the physical layer does not support multiplexing of these channels.

Multiplexing/demultiplexing of upper layer PDUs into/from transport block sets delivered to/from the physical layer on dedicated transport channels. The MAC allows service multiplexing for dedicated transport channels. This function can be utilised when several upper layer services (e.g. RLC instances) can be mapped efficiently on the same transport channel. In this case the identification of multiplexing is contained in the MAC protocol control information.

Traffic volume measurement. Measurement of traffic volume on logical channels and reporting to RRC. Based on the reported traffic volume information, RRC performs transport channel switching decisions.

Transport Channel type switching. Execution of the switching between common and dedicated transport channels based on a switching decision derived by RRC.

Ciphering. This function prevents unauthorised acquisition of data. Ciphering is performed in the MAC layer for transparent RLC mode. Access Service Class selection for RACH and CPCH transmission. The RACH resources (i.e. access slots and preamble signatures) and CPCH resources (i.e. access slots and preamble signatures) may be divided between different Access Service Classes in order to provide different priorities of RACH and CPCH usage. In addition it is possible for more than one ASC or for all ASCs to be assigned to the same access slot/signature space. Each access service class will also have a set of back-off parameters associated with it, some or all of which may be broadcast by the network. The MAC function applies the appropriate back-off and indicates to the PHY layer the RACH and CPCH partition associated to a given MAC PDU transfer.The functions of PDCP include: Header compression and decompression. Header compression and decompression of IP data streams (e.g., TCP/IP and RTP/UDP/IP headers) at the transmitting and receiving entity, respectively. The header compression method is specific to the particular network layer, transport layer or upper layer protocol combinations e.g. TCP/IP and RTP/UDP/IP. Transfer of user data. Transmission of user data means that 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.The functions of BMC include:

Storage of Cell Broadcast Messages.The BMC stores the Cell Broadcast messages received over the CBC-RNC interface for scheduled transmission.

Traffic volume monitoring and radio resource request for CBS.At the UTRAN side, the BMC calculates the required transmission rate for Cell Broadcast Service based on the messages received over the CBC-RNC interface, and requests for appropriate CTCH/FACH resources from RRC.

Scheduling of BMC messages.The BMC receives scheduling information together with each Cell Broadcast message over the CBC-RNC-interface. Based on this scheduling information, at the UTRAN side, BMC generates schedule messages and schedules BMC message sequences accordingly. At the UE side, BMC evaluates the schedule messages and indicates scheduling parameters to RRC, which are used by RRC to configure the lower layers for CBS discontinuous reception.

Transmission of BMC messages to UE.This function transmits the BMC messages (Scheduling and Cell Broadcast messages) according to schedule.

Delivery of Cell Broadcast messages to upper layer (NAS).This functions delivers the received Cell Broadcast messages to upper layer (NAS) in the UE. Only non-corrupted Cell Broadcast messages are delivered.The functions of RRC include:

The Radio Resource Control (RRC) layer handles the control plane signalling of Layer 3 between the UEs and UTRAN. The RRC performs the following functions:

Broadcast of information provided by the non-access stratum (Core Network). The RRC layer performs system information broadcasting from the network to all UEs. The system information is normally repeated on a regular basis. The RRC layer performs the scheduling, segmentation and repetition. This function supports broadcast of higher layer (above RRC) information. This information may be cell specific or not. As an example RRC may broadcast Core Network location service area information related to some specific cells.

Broadcast of information related to the access stratum. The RRC layer performs system information broadcasting from the network to all UEs. The system information is normally repeated on a regular basis. The RRC layer performs the scheduling, segmentation and repetition. This function supports broadcast of typically cell-specific information.

Establishment, re-establishment, maintenance and release of an RRC connection between the UE and UTRAN. The establishment of an RRC connection is initiated by a request from higher layers at the UE side to establish the first Signalling Connection for the UE. The establishment of an RRC connection includes an optional cell re-selection, an admission control, and a layer 2 signalling link establishment. The release of an RRC connection can be initiated by a request from higher layers to release the last Signalling Connection for the UE or by the RRC layer itself in case of RRC connection failure. In case of connection loss, the UE requests re-establishment of the RRC connection. In case of RRC connection failure, RRC releases resources associated with the RRC connection.

Establishment, reconfiguration and release of Radio Bearers. The RRC layer can, on request from higher layers, perform the establishment, reconfiguration and release of Radio Bearers in the user plane. A number of Radio Bearers can be established to an UE at the same time. At establishment and reconfiguration, the RRC layer performs admission control and selects parameters describing the Radio Bearer processing in layer 2 and layer 1, based on information from higher layers.

Assignment, reconfiguration and release of radio resources for the RRC connection. The RRC layer handles the assignment of radio resources (e.g. codes, CPCH channels) needed for the RRC connection including needs from both the control and user plane. The RRC layer may reconfigure radio resources during an established RRC connection. This function includes coordination of the radio resource allocation between multiple radio bearers related to the same RRC connection. RRC controls the radio resources in the uplink and downlink such that UE and UTRAN can communicate using unbalanced radio resources (asymmetric uplink and downlink). RRC signals to the UE to indicate resource allocations for purposes of handover to GSM or other radio systems.

RRC connection mobility functions. The RRC layer performs evaluation, decision and execution related to RRC connection mobility during an established RRC connection, such as handover, preparation of handover to GSM or other systems, cell re-selection and cell/paging area update procedures, based on e.g. measurements done by the UE. Paging/notification. The RRC layer can broadcast paging information from the network to selected UEs. Higher layers on the network side can request paging and notification. The RRC layer can also initiate paging during an established RRC connection.

Routing of higher layer PDUs. This function performs at the UE side routing of higher layer PDUs to the correct higher layer entity, at the UTRAN side to the correct RANAP entity.

Control of requested QoS. This function shall ensure that the QoS requested for the Radio Bearers can be met. This includes the allocation of a sufficient number of radio resources.

UE measurement reporting and control of the reporting. The measurements performed by the UE are controlled by the RRC layer, in terms of what to measure, when to measure and how to report, including both UMTS air interface and other systems. The RRC layer also performs the reporting of the measurements from the UE to the network.

Outer loop power control. The RRC layer controls setting of the target of the closed loop power control.

Control of ciphering. The RRC layer provides procedures for setting of ciphering (on/off) between the UE and UTRAN. Arbitration of radio resources on uplink DCH. This function controls the allocation of radio resources on uplink DCH on a fast basis, using a broadcast channel to send control information to all involved users.This function is implemented in the CRNC.

Initial cell selection and re-selection in idle mode. Selection of the most suitable cell based on idle mode measurements and cell selection criteria.

Integrity protection. This function adds a Message Authentication Code (MAC-I) to those RRC messages that are considered sensitive and/or contain sensitive information. Initial Configuration for CBSThis function performs the initial configuration of the BMC sublayer.

Allocation of radio resources for CBSThis function allocates radio resources for CBS based on traffic volume requirements indicated by BMC. The radio resource allocation set by RRC (i.e. the schedule for mapping of CTCH onto FACH/S-CCPCH) is indicated to BMC to enable generation of schedule messages. The resource allocation for CBS shall be broadcast as system information.

Configuration for CBS discontinuous receptionThis function configures the lower layers (L1, L2) of the UE when it shall listen to the resources allocated for CBS based on scheduling information received from BMC.

3.2.2 Status of RRC Protocol

In UMTS, all statuses of UE are scheduled by RRC protocol. One UE has several RRC statuses, such as, Idle and DCH. Figure 9 shows the status and status conversion (containing GSM status).

Figure 9 RRC Status and Status Conversion

UE status is defined by the channel that UE uses.

CELL_DCH status indicates that UE occupies the dedicated physical channel.

CELL_FACH status indicates that UE does not use any dedicated channel but uses the common channel when the traffic is small. UL uses RACH and DL uses FACH. In this status, UE can initiate cell reselection process and UTRAN can determine which cell UE locates in.

CELL_PCH status indicates that UE only intercepts PCH and BCH. In this status, UE can reselect the cell. During the reselection, it converts into CELL_FACH status, the cell update initiates, and it returns to CELL_PCH status. The network can determine the cell which the UE locates in.

URA_PCH status is similar to CELL_PCH status. The network can only determine the URA cell which the UE locates in.

The introduction of CELL_PCH status and URA_PCH status is to keep UE always in online status in order not to waster radio resources.

3.2.3 Some Explanations

In CELL_PCH, URA_PCH or Idle status, UE can intercept PCH and BCH, and can receive the message of Paging. In CELL_DCH or CELL_FACH status, UE cannot intercept PCH and BCH. Paging Type 2 is introduced to page UE in these two statuses.

Usually, the permanent ID information of UE (such as, IMSI) will not be saved in RNC. When UE is making a call, CN informs RNC of the IMSI of the UE with the message of Command ID of RANAP. When CN requires RNC to page a specific UE, RNC will judge which RRC status the IMSI to page is in, to decide the paging type (Paging Type 1 or Paging Type 2).

3.3 Protocol related to Interface Iu3.3.1 IU interface architecture

The Iu interface is specified at the boundary between the Core Network and UTRAN. Figure depicts the logical division of the Iu interface. From the Iu perspective, the UTRAN access point is an RNC. The Iu interface towards the PS-domain of the core network is called Iu-PS, and the Iu interface towards the CS-domain is called Iu-CS. The differences between Iu-CS and Iu-PS are treated elsewhere in the present document. The Iu interface to the Broadcast domain is called Iu-BC.There shall not be more than one Iu interface (Iu-PS) towards the PS-domain from any one RNC. Each RNC shall not have more than one Iu interface (Iu-CS) towards its default CN node within the CS domain, but may also have further Iu interfaces (Iu-CS) towards other CN nodes within the CS domain. (See [6] for definition of Default CN node.) These further Iu interfaces (Iu-CS) shall only be used as a result of intra-MSC inter-system handover or SRNS relocation, in the case the anchor CN node directly connects to the target RNC. There shall not be more than one Iu interface (Iu-BC) from an RNC towards the Broadcast domain.

In the separated core network architecture, this means that there shall be separate signalling and user data connections towards the PS and CS domains this applies in both transport and radio network layers.

In the combined architecture, there shall be separate connections in the user plane towards the PS and CS domains (in both transport and radio network layers). In the control plane, there shall be separate SCCP connections to the two logical domains.

In either architecture, there can be several RNCs within UTRAN and so UTRAN may have several Iu access points towards the Core Network. As a minimum, each Iu access point (in UTRAN or CN) shall independently fulfil the requirements of the relevant Iu specifications3.3.2 Protocol Structure of Iu Interface

Figure 10 shows the structure of Interface Iu-CS protocol and Figure 11 shows the structure of Interface Iu-PS protocol.

Figure 10 Structure of Iu-CS Protocol

Figure 11 Structure of Interface Iu-PS Protocol

RANAP: user plane application protocol. It provides the signalling service between UTRAN and CN that is required to fulfil the RANAP functions. RANAP protocol has the following functions: Relocating serving RNC. This function enables to change the serving RNC 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.

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 change 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 (see [8]). This function has two sub-classes:

1.Transport of the initial NAS signalling message from the UE to CN. This function transfers transparently the NAS information. As a consequence also the Iu signalling connection is set up.

2.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.

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

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

Location related data. This function allows the CN to either retrieve from the RNC deciphering keys (to be forwarded to the UE) for the broadcasted assistance data, or request the RNC to deliver dedicated assistance data to the UE.SCCP: The SCCP is used to support signalling messages between the CNs and the RNC. One user function of the SCCP, called Radio Access Network Application Part (RANAP), is defined. The RANAP uses one signalling connection per active UE and CN for the transfer of layer 3 messages. RANAP may use SSN, SPC and/or GT and any combination of them as addressing schemes for the SCCP. Which of the available addressing scheme to use for the SCCP is an operator matter. A new SCCP connection is established when information related to the communication between a UE and the network has to be exchanged between RNC and CN, and no SCCP connection exists between the CN and the RNC involved, for the concerned UE. MTP3B: provides message routing, discrimination and distribution (for point-to-point link only), signaling link management load sharing and changeover/back between link within one link-set. The need for multiple link-sets is precluded.SAAL-NNI: SAAL-NNI [1] consists of the following sub-layers: - SSCF [3], - SSCOP [2] and AAL5 [6]. The SSCF maps the requirements of the layer above to the requirements of SSCOP. Also SAAL connection management, link status and remote processor status mechanisms are provided. SSCOP provides mechanisms for the establishment and release of connections and the reliable exchange of signalling information between signalling entities. Adapts the upper layer protocol to the requirements of the Lower ATM cells.IUUP: user plane protocol.

GTP-U: GTP-U is used as the user data bearer towards the PS domain.RANAP Signalling is used to establish, modify and release the GTP-U tunnels towards the PS domain.AAL2: AAL2 is used as the user data bearer towards the CS domain.Q.2630.2 is used as the protocol for dynamically setup AAL-2 connections over Iu towards the CS domain. Q.2630.2 adds new optional capabilities to Q.2630.1.3.3.3 Some Explanations3.3.3.1 SRNS RelocationOne case:

UE crosses 2 RNSs during the move, as shown in Figure 12.

Figure 12 SRNS Relocation (I)

One UE can use 2 RNSs at the same time. The data can be sent on two RLs. In addition, the data that UE sends to DRNC is sent to SRNC via Interface Iur, and SRNC will combine them and send to CN.

If UE continues to move, the RL deterioration of UE on SRNS cannot be used again, which will cause the following case.

Figure 13 SRNS relocation (II)

UE and SRNC have no direct contact, but all data still pass SRNC and reach CN via Interface Iur. It will cause the waste of resources. Therefore, SRNS relocation should be initiated, which can move Interface Iu from SRNC to DRNC. In the course of SRNC relocation, SRNC (Serving RNC) is also called Source RNC and DRNC is also called Target RNC. Figure 14 shows the result after the relocation completes.

Figure 14 SRNS Relocation (III)

SRNS relocation is the process to move Interface Iu from Source RNC to Target RNC.

3.3.4 RANAP Process

Table 1 Class 1

Elementary ProcedureInitiating MessageSuccessful OutcomeUnsuccessful Outcome

Response messageResponse message

Iu ReleaseIU RELEASE COMMANDIU RELEASE COMPLETE

Relocation PreparationRELOCATION REQUIREDRELOCATION COMMANDRELOCATION PREPARATION FAILURE

Relocation Resource AllocationRELOCATION REQUESTRELOCATION REQUEST ACKNOWLEDGERELOCATION FAILURE

Relocation CancelRELOCATION CANCELRELOCATION CANCEL ACKNOWLEDGE

SRNS Context TransferSRNS CONTEXT REQUESTSRNS CONTEXT RESPONSE

Security Mode ControlSECURITY MODE COMMANDSECURITY MODE COMPLETESECURITY MODE REJECT

Data Volume ReportDATA VOLUME REPORT REQUESTDATA VOLUME REPORT

ResetRESETRESET ACKNOWLEDGE

Reset ResourceRESET RESOURCERESET RESOURCE ACKNOWLEDGE

Location related DataLOCATION RELATED DATA REQUESTLOCATION RELATED DATA RESPONSELOCATION RELATED DATA FAILURE

Table 2 Class 2

Elementary ProcedureMessage

RAB Modification RequestRAB MODIFY REQUEST

RAB Release RequestRAB RELEASE REQUEST

Iu Release RequestIU RELEASE REQUEST

Relocation DetectRELOCATION DETECT

Relocation CompleteRELOCATION COMPLETE

SRNS Data Forwarding InitiationSRNS DATA FORWARD COMMAND

SRNS Context Forwarding from Source RNC to CNFORWARD SRNS CONTEXT

SRNS Context Forwarding to Target RNC from CNFORWARD SRNS CONTEXT

PagingPAGING

Common IDCOMMON ID

CN Invoke TraceCN INVOKE TRACE

CN Deactivate TraceCN DEACTIVATE TRACE

Location Reporting ControlLOCATION REPORTING CONTROL

Location ReportLOCATION REPORT

Initial UE MessageINITIAL UE MESSAGE

Direct TransferDIRECT TRANSFER

Overload ControlOVERLOAD

Error IndicationERROR INDICATION

Table 3 Class 3

Elementary ProcedureInitiating MessageResponse Message

RAB AssignmentRAB ASSIGNMENT REQUESTRAB ASSIGNMENT RESPONSE x N (N>=1)

3.4 Protocol related to Interface IurThe highest layer protocol of Interface Iur control plane is RANSAP. Figure 15 shows the structure of Interface Iur protocol.

Figure 15 Structure of Interface Iur Protocol

The protocol structure of Interface Iur control plane (including RNL and TNL) is same as that of Interface Iu control plane.

3.4.1 Function and Structure of Interface Iur

Interface Iur is to transmit data when UE performs the soft handover between adjacent RNCs.

3GPP prescribes that Interface Iur is a logic entity. That is, Interface Iur and Interface Iu can either share one channel for the transmission or connect via independent physical interface.

3.4.2 DCH Frame Protocol of Interface Iur

As shown in Figure,when UE crosses RNSs, DRNC can forward DCH data to SRNC via Interface Iur. DRNC does not process DCH data but directly send DCH data at Interface Iub to Interface Iur. DCH frames of Interface Iur and Interface Iub keep consistent, to greatly reduce DCH data processing by DRNC.3.4.3 RNSAP Process

Table 4 Class 1 Elementary Procedures

Elementary ProcedureInitiating MessageSuccessful OutcomeUnsuccessful Outcome

Response messageResponse message

Radio Link SetupRADIO LINK SETUP REQUESTRADIO LINK SETUP RESPONSERADIO LINK SETUP FAILURE

Radio Link AdditionRADIO LINK ADDITION REQUESTRADIO LINK ADDITION RESPONSERADIO LINK ADDITION FAILURE

Radio Link DeletionRADIO LINK DELETION REQUESTRADIO LINK DELETION RESPONSE

Synchronised Radio Link Reconfiguration PreparationRADIO LINK RECONFIGURATION PREPARERADIO LINK RECONFIGURATION READYRADIO LINK RECONFIGURATION FAILURE

Unsynchronised Radio Link ReconfigurationRADIO LINK RECONFIGURATION REQUESTRADIO LINK RECONFIGURATION RESPONSERADIO LINK RECONFIGURATION FAILURE

Physical Channel ReconfigurationPHYSICAL CHANNEL RECONFIGURATION REQUESTPHYSICAL CHANNEL RECONFIGURATION COMMANDPHYSICAL CHANNEL RECONFIGURATION FAILURE

Dedicated Measurement InitiationDEDICATED MEASUREMENT INITIATION REQUESTDEDICATED MEASUREMENT INITIATION RESPONSEDEDICATED MEASUREMENT INITIATION FAILURE

Common Transport Channel Resources InitialisationCOMMON TRANSPORT CHANNEL RESOURCES REQUESTCOMMON TRANSPORT CHANNEL RESOURCES RESPONSECOMMON TRANSPORT CHANNEL RESOURCES FAILURE

Common Measurement InitiationCOMMON MEASUREMENT INITIATION REQUESTCOMMON MEASUREMENT INITIATION RESPONSECOMMON MEASUREMENT INITIATION FAILURE

Information Exchange InitiationINFORMATION EXCHANGE INITIATION REQUESTINFORMATION EXCHANGE INITIATION RESPONSEINFORMATION EXCHANGE INITIATION FAILURE

Table 5 Class 2 Elementary Procedures

Elementary ProcedureInitiating Message

Uplink Signalling TransferUPLINK SIGNALLING TRANSFER INDICATION

Downlink Signalling TransferDOWNLINK SIGNALLING TRANSFER REQUEST

Relocation CommitRELOCATION COMMIT

PagingPAGING REQUEST

Synchronised Radio Link Reconfiguration CommitRADIO LINK RECONFIGURATION COMMIT

Synchronised Radio Link Reconfiguration CancellationRADIO LINK RECONFIGURATION CANCEL

Radio Link FailureRADIO LINK FAILURE INDICATION

Radio Link RestorationRADIO LINK RESTORE INDICATION

Dedicated Measurement ReportingDEDICATED MEASUREMENT REPORT

Dedicated Measurement TerminationDEDICATED MEASUREMENT TERMINATION REQUEST

Dedicated Measurement FailureDEDICATED MEASUREMENT FAILURE INDICATION

Downlink Power Control [FDD]DL POWER CONTROL REQUEST

Compressed Mode Command [FDD]COMPRESSED MODE COMMAND

Common Transport Channel Resources ReleaseCOMMON TRANSPORT CHANNEL RESOURCES RELEASE REQUEST

Error IndicationERROR INDICATION

Downlink Power Timeslot Control [TDD]DL POWER TIMESLOT CONTROL REQUEST

Radio Link Pre-emptionRADIO LINK PREEMPTION REQUIRED INDICATION

Radio Link CongestionRADIO LINK CONGESTION INDICATION

Common Measurement ReportingCOMMON MEASUREMENT REPORT

Common Measurement TerminationCOMMON MEASUREMENT TERMINATION REQUEST

Common Measurement FailureCOMMON MEASUREMENT FAILURE INDICATION

Information ReportingINFORMATION REPORT

Information Exchange TerminationINFORMATION EXCHANGE TERMINATION REQUEST

Information Exchange FailureINFORMATION EXCHANGE FAILURE INDICATION

3.5 Protocol Related to Interface Iub

The high layer protocol of Interface Iub control plane is NBAP. The user plane consists of several frame protocols. Figure 16 shows the structure of protocols.

Figure 16 Structure of Interface Iub Protocol

NBAP includes Node B logic O&M and dedicated NBAP.

3.5.1 Node B Logic Model

Figure 17 Node B Logic Model

Node B logic model consists of cell, common transmission channel/port, Node B communication context, and the corresponding DSCH/DCH. Node B controls NCP and the communication controls port CCP, etc.Node B communication context and the corresponding DSCH/DCH port are related to dedicated user services.Node B communication context is corresponding to CRNC communication context.Node B communication context is identifies by Node B Communication Text ID, containing necessary information to communicate with UE. It is established when RL is setup and deleted when RL is deleted.There is only one NCP link on one Node B. RNC sends all Node B common control signaling from NCP. NCP link must be setup before operating, maintaining, and controlling Node B. There can be several CCP links on one Node B. RNC sends all Node B dedicated control signaling from CCP link. Usually, one cell inside Node B can be configured with one CCP (it is just a routine, not certain.)3.5.2 NBAP Process

Table 6 Class 1

Elementary ProcedureMessageSuccessful OutcomeUnsuccessful Outcome

Response messageResponse message

Cell SetupCELL SETUP REQUESTCELL SETUP RESPONSECELL SETUP FAILURE

Cell ReconfigurationCELL RECONFIGURATION REQUESTCELL RECONFIGURATION RESPONSECELL RECONFIGURATION FAILURE

Cell DeletionCELL DELETION REQUESTCELL DELETION RESPONSE

Common Transport Channel SetupCOMMON TRANSPORT CHANNEL SETUP REQUESTCOMMON TRANSPORT CHANNEL SETUP RESPONSECOMMON TRANSPORT CHANNEL SETUP FAILURE

Common Transport Channel ReconfigurationCOMMON TRANSPORT CHANNEL RECONFIGURATION REQUEST COMMON TRANSPORT CHANNEL RECONFIGURATION RESPONSECOMMON TRANSPORT CHANNEL RECONFIGURATION FAILURE

Common Transport Channel DeletionCOMMON TRANSPORT CHANNEL DELETION REQUESTCOMMON TRANSPORT CHANNEL DELETION RESPONSE

Physical Shared Channel Reconfigure [TDD]PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSEPHYSICAL SHARED CHANNEL RECONFIGURATION FAILURE

AuditAUDIT REQUEST AUDIT RESPONSEAUDIT FAILURE

Block ResourceBLOCK RESOURCE REQUESTBLOCK RESOURCE RESPONSEBLOCK RESOURCE FAILURE

Radio Link SetupRADIO LINK SETUP REQUESTRADIO LINK SETUP RESPONSERADIO LINK SETUP FAILURE

System Information Update SYSTEM INFORMATION UPDATE REQUESTSYSTEM INFORMATION UPDATE RESPONSESYSTEM INFORMATION UPDATE FAILURE

Common Measurement InitiationCOMMON MEASUREMENT INITIATION REQUESTCOMMON MEASUREMENT INITIATION RESPONSECOMMON MEASUREMENT INITIATION FAILURE

Radio Link AdditionRADIO LINK ADDITION REQUESTRADIO LINK ADDITION RESPONSERADIO LINK ADDITION FAILURE

Radio Link DeletionRADIO LINK DELETION REQUESTRADIO LINK DELETION RESPONSE

Synchronised Radio Link Reconfiguration PreparationRADIO LINK RECONFIGURATION PREPARERADIO LINK RECONFIGURATION READYRADIO LINK RECONFIGURATION FAILURE

Unsynchronised Radio Link ReconfigurationRADIO LINK RECONFIGURATION REQUESTRADIO LINK RECONFIGURATION RESPONSERADIO LINK RECONFIGURATION FAILURE

Dedicated Measurement InitiationDEDICATED MEASUREMENT INITIATION REQUESTDEDICATED MEASUREMENT INITIATION RESPONSEDEDICATED MEASUREMENT INITIATION FAILURE

ResetRESET REQUESTRESET RESPONSE

Cell Synchronisation Initiation [3.84Mcps TDD]CELL SYNCHRONISATION INITIATION REQUESTCELL SYNCHRONISATION INITIATION RESPONSECELL SYNCHRONISATION INITIATION FAILURE

Cell Synchronisation Reconfiguration [3.84 Mcps TDD]CELL SYNCHRONISATION RECONFIGURATION REQUESTCELL SYNCHRONISATION RECONFIGURATION RESPONSECELL SYNCHRONISATION RECONFIGURATION FAILURE

Cell Synchronisation Adjustment [3.84Mcps TDD]CELL SYNCHRONISATION ADJUSTMENT REQUESTCELL SYNCHRONISATION ADJUSTMENT RESPONSECELL SYNCHRONISATION ADJUSTMENT FAILURE

Information Exchange InitiationINFORMATION EXCHANGE INITIATION REQUESTINFORMATION EXCHANGE INITIATION RESPONSEINFORMATION EXCHANGE INITIATION FAILURE

Table 7 Class 2

Elementary ProcedureMessage

Resource Status IndicationRESOURCE STATUS INDICATION

Audit RequiredAUDIT REQUIRED INDICATION

Common Measurement ReportingCOMMON MEASUREMENT REPORT

Common Measurement TerminationCOMMON MEASUREMENT TERMINATION REQUEST

Common Measurement FailureCOMMON MEASUREMENT FAILURE INDICATION

Synchronised Radio Link Reconfiguration CommitRADIO LINK RECONFIGURATION COMMIT

Synchronised Radio Link Reconfiguration CancellationRADIO LINK RECONFIGURATION CANCEL

Radio Link FailureRADIO LINK FAILURE INDICATION

Radio Link RestorationRADIO LINK RESTORE INDICATION

Dedicated Measurement ReportingDEDICATED MEASUREMENT REPORT

Dedicated Measurement TerminationDEDICATED MEASUREMENT TERMINATION REQUEST

Dedicated Measurement FailureDEDICATED MEASUREMENT FAILURE INDICATION

Downlink Power Control [FDD]DL POWER CONTROL REQUEST

Compressed Mode Command [FDD]COMPRESSED MODE COMMAND

Unblock ResourceUNBLOCK RESOURCE INDICATION

Error IndicationERROR INDICATION

Downlink Power Timeslot Control [TDD]DL POWER TIMESLOT CONTROL REQUEST

Radio Link Pre-emptionRADIO LINK PREEMPTION REQUIRED INDICATION

Cell Synchronisation Reporting [3.84Mcps TDD]CELL SYNCHRONISATION REPORT

Cell Synchronisation Termination [3.84Mcps TDD]CELL SYNCHRONISATION TERMINATION REQUEST

Cell Synchronisation Failure [3.84Mcps TDD]CELL SYNCHRONISATION FAILURE INDICATION

Information ReportingINFORMATION REPORT

Information Exchange TerminationINFORMATION EXCHANGE TERMINATION REQUEST

Information Exchange FailureINFORMATION EXCHANGE FAILURE INDICATION

_1021361919.doc

2. Radio Link Setup Request

UE

Serving

RNC

Node B

Serving RNS

NBAP

5. Downlink Synchronisation

DCH-FP

4. ALCAP Iub Data Transport Bearer Setup

6. Uplink Synchronisation

DCH-FP

NBAP

DCH-FP

DCH-FP

1. CCCH : RRC Connection Request

RRC

3. Radio Link Setup Response

Allocate RNTISelect L1 and L2 parameters

RRC

8. DCCH : RRC Connection Setup Complete

RRC

RRC

7. CCCH : RRC Connection Setup

RRC

RRC

Start TX description

Start RX description

NBAP

NBAP

_1044191997.doc

PHY

MAC

U-plane information

C-plane signalling

Logical Channels

Transport Channels

RLC

RLC

RLC

L2/BMC

RLC

RLC

L3

RLC

L2/MAC

L1

GC

Nt

DC

L2/RLC

RLC

RLC

control

Duplication avoidance

control

control

Radio Bearers

RRC

UuS boundary

control

BMC

L2/PDCP

PDCP

PDCP

GC

control

Nt

DC

_1390133282.doc

Radio

(Uu)

UE

CN

Access Stratum

Non-Access Stratum

Iu

Radioproto-cols

(1)

Radioproto-cols

(1)

Iu protocols

(2)

Iu protocols

(2)

_1035185631.doc

ATM

Physical Layer

GTP-U

UDP

IP

SSCF-NNI

AAL5

SCCP

SCTP

IP

AAL5

MTP3-B

SSCOP

SSCF-NNI

ATM

Radio

Network

Layer

Transport Network

Control Plane

Network

Plane

Transport

User

User Plane

Control Plane

Network

Plane

Transport

User

Physical Layer

Transport

Network

Layer

Iu UP Protocol Layer

RANAP

M3UA

_1040546557.doc

Physical Layer

Transport

Layer

Radio Network

Layer

RACH FP

SSCOP

ALCAP

AAL Type 2

DCH FP

Node B Application Part (NBAP)

Radio Network

Control Plane

Transport

Network Control Plane

SSCF-UNI

ATM

User Plane

AAL Type 5

USCH FP

SSCOP

DSCH FP

SSCF-UNI

AAL Type 5

Q.2150.2

Q.2630.1

PCH FP

FACH FP

CPCH FP

_1012738950.doc

Iu-BC

Node B

Node B

Node B

Node B

RNC

RNC

CS Domain

BC Domain

UTRAN

Core Network (CN)

Iu Interface

Iu-CS

PS Domain

Iu-PS

_1015237365.doc

SSCF-NNI

SSCOP

MTP3-B

AAL5

IP

SCTP

SCCP

AAL5

SSCF-NNI

STC (Q.2150.1)

RNSAP

Iur

Data

Stream(s)

Transport

Network

Layer

Physical Layer

Transport

User

Network

Plane

Control Plane

User Plane

Transport

User

Network

Plane

Transport Network

Control Plane

Radio

Network

Layer

ATM

ALCAP(Q.2630.1)

AAL2

SSCF-NNI

SSCOP

MTP3-B

IP

SCTP

SSCF-NNI

M3UA

M3UA

_999929116.doc

SSCF-NNI

SCCP

MTP3b

MTP3b

AAL5

AAL2

SSCF-NNI

SSCOP

AAL5

SSCOP

ATM

Radio

Network

Layer

Transport Network

Control Plane

Network

Plane

Transport

User

User Plane

Control Plane

Network

Plane

Transport

User

Physical Layer

Transport

Network

Layer

Iu UP Protocol

Layer

RANAP

Q.2630.1

Q.2150.1