Transcript wcdmaranprotocolsandprocedures-120913010015-phpapp01

WCDMA RAN Protocols and Procedures
Chapter 8
Iu Interface - RANAP Protocol
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Objectives of Chapter 8,
Iu Interface - RANAP Protocol
After this chapter the participants will be able to:
1.
Explain the Iu interface and the Radio Access Network Application Protocol
(RANAP) protocol structure.
2.
Explain the main functions and procedures of RANAP.
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RADIO ACCESS NETWORK
APPLICATION PART (RANAP)
PROTOCOL
---INTRODUCTION---
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• The Iu interface connects WCDMA RAN to the Core Network.
• The Radio Access Network Application Part (RANAP) protocol is used over
the Iu interface
• RANAP carries Non-Access Stratum (NAS) messages, which are relayed
between the CN nodes and the Ues.
• The Iu interface is divided into two instances:
* the Iu Circuit Switched (CS) to connect WCDMA RAN to the MSC server
* the Iu Packet Switched (PS) to connect to the SGSN
• The Iu interface is divided into:
* a control plane
* a user plane.
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Iu-CS Interface (figure 8-1)
RNL
Control Plane
User Plane
Iu UP protocol
layer
RANAP
TNL
TN User Plane
TN Control Plane
TN User Plane
Q.2630.1
SCCP
MTP3b
Q.2150.1
MTP3b
NNI-SAAL
NNI-SAAL
AAL2
ATM
Physical Layer
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Iu-PS Interface (figure 8-2)
RNL
Control Plane
User Plane
Iu UP protocol
layer
RANAP
TNL
TN User Plane
TN Control Plane
SCCP
MTP3b
TN User Plane
GTP-U
UDP
IP
AAL5
NNI -SAAL
ATM
ATM
Physical Layer
Physical Layer
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RANAP signaling over the lu interface
MSC/VLR
(figure 8-3)
NAS-messages
MGW
RANAP
Iu UP
Uu
Node B
(RBS 3000)
Iub
RNC
Iu UP
RANAP
SGSN
NAS-messages
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RADIO ACCESS NETWORK
APPLICATION PART (RANAP)
PROTOCOL
---RANAP PROTOCOL STACK---
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1. RANAP uses the SS7 over ATM protocol stack for signaling transport.
2.
Signaling Connection Control Part (SCCP) are used to transmit RANAP
PDUs over the broadband MTP architecture:
(1) connection-oriented
•
For Dedicated control services: maintenance of an associated Iu signaling
connection for a specific UE (such as NAS messages ).
(2) connectionless services
•
For General control services : relate to the entire Iu interface instance
between an RNC and the CN (such as block and reset ).
•
For Notification services : relate to a single UE or all UE's in a specified
area (such as paging)
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RANAP Protocol stack
(figure 8-4)
IuPS
SGSN
Uu
Iub
IuCS
SRNC
RANAP Signaling
MSC
RANAP
RANAP
SCCP SAP
SCCP SAP
SCCP
SCCP
MTP-3B
MTP-3B
NNI-SAAL
Lower layer signaling
NNI-SAAL
AAL5
AAL5
ATM
ATM
PHY
PHY
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IU USER PLANE (UP)
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1. The Iu User Plane protocol is part of the Radio Network Layer.
2. The purpose of the User Plane protocol : to carry user data related to RABs
over the Iu interface.
3. The protocol supports two modes:
(1) Transparent Mode (TrM)
• protocol does not perform any framing or control. For instance, the transfer
of GTP-U PDUs (packet data) could utilize the transparent mode of the Iu UP
protocol.
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(2) Support Mode for Predefined SDU sizes (SMpSDU)
• performs framing of the user data into segments of predefined size.
correspond to AMR speech frames, or derived from the data rate of a
CS data call.
• control procedures for initialization and rate control are defined
• functionality is specified for indicating the quality of the frame based, for
example, on CRC from the radio interface .
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Iu UP protocol layer in transparent occurrence over Iu
interface
Iu Interface
UTRAN
CN
(figure 8-5)
RNL-SAP
Iu UP layer in
transparent mode
Radio Interface
Protocols
Iu UP layer in
transparent mode
TNL-SAP
TNL-SAP
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Iu UP protocol layer in support mode occurrence over Iu
interface
Iu Interface
UTRAN
CN
(figure 8-6)
RNL-SAP
Radio Interface
Protocols
Iu UP layer in
support mode
Iu UP layer in
support mode
Support Mode
Functions
Support Mode
Functions
Transfer of Iu
UP protocol
frames
TNL-SAP
TNL-SAP
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Transport Network Control Plane for Iu CS
(figure 8-7)
Uu
Iub
IuCS
SRNC
Q.2630.1 Signaling
Q.2630.1
MGW
Q.2630.1
Q.2150.1
Q.2150.1
MTP-3B
MTP-3B
NNI-SAAL
Lower layer signaling
NNI-SAAL
AAL5
AAL5
ATM
ATM
PHY
PHY
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Transport Network User Plane for Iu CS
(figure 8-8)
Uu
Iub
IuCS
SRNC
MGW
Iu UP
Iu UP
AAL2
AAL2
ATM
ATM
PHY
PHY
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Transport Network User Plane for Iu PS
(figure 8-9)
Uu
Iub
IuPS
SGSN
SRNC
Signaling
GTP-U
GTP-U
UDP
UDP
IP
IP
Lower layer signaling
AAL5
AAL5
ATM
ATM
PHY
PHY
• a GTP-U tunnel is set up by RANAP.
• It only needs an identifier for the tunnel and the IP addresses for the RNC and SGSN.
• Further on a GTP-U tunnel is set up between the SGSN and the GGSN.
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Iu Connections between RNC and the Core Network
(figure 8-10)
User Plane/AAL2
Q.AAL2
RANAP
User Plane/GTP-U
RANAP
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FUNCTIONS OF RANAP
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1. RANAP supports functionalities that are implemented by various RANAP
Elementary Procedures (EPs). Each function may require the execution of one
or more EPs.
2. Three kinds of EPs are used:
–Class 1: EPs with response (success and/or failure)
–Class 2: EPs without response
–Class 3: EPs with possibility of multiple responses
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3. RANAP has the following functions:
• Paging
This function provides the CN for capability to page the UE.
• Common ID management
IMSI of the UE is sent from the CN to WCDMA RAN .
• Transport of NAS information between UE and CN.
provides transparent transfer of UE-CN signaling messages that are not
interpreted by WCDMA RAN.
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• Security mode control
used to send the security keys and the algorithms (ciphering and integrity
protection) to the WCDMA RAN, and setting the operation mode for security
functions.
• Radio Access Bearer (RAB) Management
responsible for setting up, modifying and releasing RABs.
• Iu Release
Releases all resources (control and user plane) from a given instance of Iu
related to the specified UE.
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• Relocating Serving RNC (SRNC)
* handles both SRNS relocation (not implemented) and hard handover.
* In SRNC relocation the serving Radio Network Subsystems (RNS)
functionality is relocated from one RNS to another without changing the
radio resources and without interrupting the user data flow. Only when all
Radio Links are already in the same DRNC that is target for the relocation.
• Management of overload
Controls the overload of the Iu interface.
• Reset
used to reset the Iu interface in error situations.
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• Location reporting
allows the CN to receive information on the location of the given UE.
• Data volume reporting
responsible for reporting unsuccessfully transmitted data
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RANAP PROCEDURES
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Paging
 Paging is used by the CN to page a UE
– This procedure uses connectionless signaling
 The PAGING message includes:
– Permanent NAS UE Identity (i.e. IMSI) for calculation of paging group and also
for WCDMA RAN paging co-ordination.
* paging coordination means that if a Radio Resource Control (RRC) connection
already exists for this UE, the radio-interface paging-message will be sent via this
RRC connection instead of via the broadcast paging channel.
– The DRX Cycle Length Coefficient (if available) may be included in the Paging
message, which used for calculating the paging occasions for the UE.
– Temporary UE ID (that is, the TMSI). Used over the paging channel. If TMSI is not
included the RNC shall use the Permanent NAS UE Identity instead,
– Paging Cause shall indicate the reason for sending the paging message.
– Non Searching Indication.
 If set to non-searching, the RNC does not need to do WCDMA RAN paging
co-ordination.
– Paging Area.
 Can be the LAI, RAI and (if omitted) the whole RNC area.
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Initial UE Message
 The Initial UE Message procedure is used to establish an Iu signaling connection
between a CN domain and the RNC.
– This procedure uses connection oriented signaling.
 The SRNC sends a SSCP Connect Request (CR) message to the CN. The SCCP
Connection Request message carries the RANAP Initial UE message.
 The Initial UE Message carries the NAS messages with the establishment cause,
the UE identity and the current location, on cell level of the UE.
 The SRNC receives confirmation that the signaling connection has been setup by
a SCCP Connection Confirm (CC) message. The SCCP CC message may include
a RANAP message, for example “Common Id”
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Common ID
 The Common ID procedure informs the RNC about the permanent NAS UE
Identity (i.e. IMSI).
– This procedure uses connection oriented signaling.
 The permanent NAS UE Identity is tied to the RRC connection and is used at
Paging to check if an RRC connection already exists for this UE;
– That is WCDMA RAN paging co-ordination.
 The WCDMA RAN also needs the permanent NAS UE Identity from this
message in order to be able to calculate the paging group in case of WCDMA
RAN initiated paging.
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Direct Transfer
 The Direct Transfer procedure is used to transfer NAS information between the
CN and the RNC or vice versa.
– This procedure uses connection oriented signaling.
 Besides NAS-PDU for the NAS information, this message also includes
– SAPI for indicating the priority of the message. SAPI 0 for high priority and
SAPI 3 for low priority (SMS). Only used downlink.
– LAI + RAC. Needed in connection with Routing Area Update. Only used
towards the PS domain.
 In this specific case Direct Transfer is used for Authentication and Ciphering
Request and Response.
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Security Mode Control
 The Security Mode Control procedure is used by the CN to pass
cipher and integrity protection information to the WCDMA RAN.
– This procedure uses connection oriented signaling.
 Messages
– If WCDMA RAN can support the requested ciphering and integrity
protection, the message SECURITY MODE COMPLETE is returned.
– Otherwise the message SECURITY MODE REJECT with an appropriate
cause value is returned.
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Security Mode Control continued
 In case a UE has RABs towards both the PS and CS CNs (not
supported), the following is valid:
– User data for RABs towards CS are ciphered with the ciphering key
received from the CS domain.
– User data for RABs towards PS are ciphered with the ciphering key
received from the PS domain.
– Signaling data is ciphered and integrity protected with the latest received
keys.
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RAB Assignment
 The RAB Assignment procedure is used to establish one or more new RABs for a
given UE and/or to modify or release already existing RABs.
– This procedure uses connection oriented signaling.
 The RAB Establishment consists of two parts:
– Iu bearer setup between the CN and the SRNC.
– Radio Bearer Setup between the UE and the SRNC.
 The RAB ASSIGNMENT REQUEST message contains:
– list of RABs to establish with their bearer characteristics
– list of RABs to modify with their bearer characteristics
– list of RABs to release
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RAB Assignment continued
 Upon reception of RAB ASSIGNMENT REQUEST, the WCDMA RAN executes
the requested configuration. The result is reported to CN in one or more RAB(s)
ASSIGNMENT RESPONSE messages. The first of these messages contains:
–
–
–
–
–
successfully established RABs
successfully modified RABs
released RABs
RABs failed to establish, modify or release
queued RABs
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RAB Assignment continued
 The subsequent messages are used for reporting the outcome of the queued RABs.
(The procedure is not completed until all RABs have been reported.)
 The following outcomes are possible:
– successfully established or modified
– failed to establish or modify
– failed to establish due to timer expiry
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Iu Release
(figure 8-12)
 The Iu Release procedure is used to release an Iu connection and
all WCDMA RAN resources related to that Iu connection.
– This procedure uses connection oriented signaling.
 Any RABs still existing for the UE will also be released.
RNC
CN
”Iu Release Command”
”Iu Release Complete ”
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Iu Release Request
 This procedure is used by WCDMA RAN to ask the CN to initiate
the release of an Iu connection.
– This procedure uses connection oriented signalling.
 The CN can follow the request and initiate the Iu Release
procedure. It can, however, also choose to take some other action,
including ignoring the request.
RNC
CN
”Iu Release Request”
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