KR101446806B1 - Method for preventing from call drop and Apparatus therefor - Google Patents

Abstract

The present invention relates to a method and system for preventing arc cutting. A method for preventing call truncation in a Serving Radio Network Subsystem (SRNS) reassignment from a source RNC to a target RNC in a mobile terminal, the method comprising the steps of: (a) receiving a network movement information message from the target RNC; (B) transmitting a network movement information confirmation message to the target RNC; and (c) when the initialization of the RLC is performed after transmitting the network movement information confirmation message, And (d) retransmitting the network movement information confirmation message. According to the present invention, it is possible to prevent a call from being truncated due to an exception occurrence during SRNS relocation.

SRNS reassignment, UMI, UMIC, source RNC, target RNC, retransmission, RLC initialization

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for preventing arc cutting,

The present invention relates to a call blocking prevention method and a radio network controller, and more particularly, to a method and an apparatus for preventing a call from being disconnected due to an exception occurrence during an SRNS relocation procedure.

A UMTS Terrestrial Radio Access Network (UTRAN) of a third generation mobile communication system is composed of a plurality of radio network subsystems (RNS), and one RNS includes a plurality of Node Bs and a Radio Network Controller Hereinafter referred to as 'RNC').

The Node B serves as an access point for connecting a User Equipment (UE) to the UTRAN, and the RNC performs radio resource allocation and management functions for each UE.

The UE is connected to a core network (CN) such as an exchange or SGSN via an RNC. In order to set a shorter path between the UE and the CN according to the movement of the UE, To a target RNC belonging to another SRNS belongs to the SRNC.

In general, the SRNS relocation is performed so that no data is lost. To this end, the acknowledged mode (AM) mode RLC entity in the user plane and control plane participates in the SRNS relocation process.

In the SRNS reassignment, the source RNC delivers the information about the unconfirmed data to the target RNC and the serial number for the data to be sent in the downlink or the uplink.

When the target RNC receives the above information, a UTRAN Mobility Information (UMI) procedure is performed between the target RNC and the UE.

However, when RLC initialization or other exception occurs during the UMI procedure according to the related art, there is a problem that call truncation occurs.

1 and 2 are views showing examples of arc cutting according to the prior art.

First, referring to FIG. 1, when a source RNC delivers information about unacknowledged data or the like to a target RNC, a UMI procedure is started (step 100).

At the start of the UMI procedure, the RRC (Radio Resource Control) entity of the target RNC transmits the UMI message to the RRC entity of the UE (step 102).

The RRC entity and the Radio Link Control (RLC) entity of the UE perform an RLC configuration process (step 104).

After the RLC scheduling process, the RRC entity of the UE transmits a UMIC (UMI Confirm) message to the RRC entity of the target RNC (step 106).

At this time, if the RLC of the UE receives an ACK for the UMIC from the RLC of the target RNC, the SRNS reallocation is normally completed. At this time, the RRC of the UE performs RLC initialization according to the RLC programming procedure, and accordingly, the RRC of the UE transmits an UMIC message having an initial sequence number (SN 0). Therefore, the RLC entity of the target RNC must transmit an ACK for the UMIC having the next sequence number so that the SRNS relocation can be completed.

However, due to the sequence number information received from the source RNC by the RLC of the target RNC, the RLC of the UE may transmit an ACK with a sequence number (for example, SN 9) other than the sequence number (for example, SN 1) In case of transmitting (step 108), it is determined that the RRC of the UE does not normally receive the ACK for the UMIC, and the UE transits to the idle state (step 110).

That is, due to the mismatch of the serial numbers, the RRC termination (DISCONNECT) procedure of the UE is performed, thereby causing a call drop (step 112).

2 is a view showing another example of arc cutting according to the prior art.

In FIG. 2, steps 200 to 206 for receiving the UMI message transmission, RLC combination and UMIC message of the target RNC according to the start of the UMI procedure are the same as those of steps 100 to 106 of FIG.

Referring to FIG. 2, as the target RNC receives information on the unacknowledged data from the source RNC, the target RNC waits for an ACK reception from the UE that the source RNC has not received.

At this time, the target RNC must receive an ACK corresponding to the next serial number of the data transmitted by the source RNC. As the RLC programming process is performed by the UMI reception, the RLC of the target RNC receives the waiting sequence number The ACK is not received.

Accordingly, the RLC entity of the target RNC transmits an RLC initialization (RLC RESET) message to the RLC entity of the UE (step 208).

The RRC of the UE determines that the normal ACK for the UMIC has not been received by the reception of the RLC initialization message, performs the RRC DISCONNECT procedure (step 210), and ends the UMI procedure (step 212).

Generally, according to 3GPP, only a case of normally transmitting / receiving a message between a target RNC and a UE in SRNS relocation is defined. As shown in FIGS. 1 and 2, in the SRNS relocation process, (For example, an ACK) due to a procedure in which the sequence numbers of data to be transmitted and received are inconsistent or incomplete between the source RNC and the UE is not defined .

Since the processing method in the case where an exception occurs between the target RNC and the UE is not defined in the 3GPP standard, there is a problem that the call is disconnected unconditionally in the conventional case.

In order to solve the problems of the related art as described above, the present invention proposes a call blocking prevention method and apparatus for preventing a call from being disconnected even if an exception occurs in the SRNS relocation.

In order to achieve the above object, according to a preferred embodiment of the present invention, there is provided a method for preventing a call disconnection in a mobile terminal from a Serving Radio Network Subsystem (SRNS) reassignment from a source RNC to a target RNC, (A) receiving a network movement information message from the RNC; (B) performing an RLC configuration process; (C) transmitting a network movement information confirmation message to the target RNC; And (d) retransmitting the network movement information confirmation message to the target RNC when initialization of the RLC is performed after transmitting the network movement information confirmation message. .

According to another aspect of the present invention, there is provided a method of preventing call truncation in a target RNC in a Serving Radio Network Subsystem (SRNS) reassignment, comprising: transmitting a network movement information message to a mobile terminal ); (B) receiving a network movement information confirmation message from the mobile terminal; (C) receiving the network movement information confirmation message retransmitted by the mobile station when initialization of the RLC of the mobile station and the target RNC is performed; And (d) transmitting, to the mobile station, a response message having a next sequence number of the network movement information confirmation message, in the SRNS relocation.

According to another aspect of the present invention, when the SRNC is reallocated from the source RNC to the target RNC, the RNC receives the network movement information message from the RRC entity of the target RNC, transmits a network movement information confirmation message, An RRC entity for retransmitting the network movement confirmation message to the RRC of the target RNC when RLC initialization is performed; And an RLC entity configured to perform initialization with an RLC of the target RNC when an exception occurs before receiving a response to the network movement information confirmation message, An apparatus is provided that includes an entity.

According to another aspect of the present invention, in a radio network controller for processing an SRNS relocation, when unacknowledged data and a serial number are received from a source RNC, a network movement information message is transmitted to the mobile station, Receiving RRC entity; And an initialization step of initializing the RLC and the RLC of the mobile station if an exception occurs before transmitting the response to the network movement information confirmation message, and when the RLC entity initializes the mobile movement information retransmitted to the RRC entity And a RLC entity for transmitting a response to the network movement information confirmation message to the RLC of the mobile station when the message is received.

According to the present invention, when an exception occurs during the SRNS relocation, the mobile terminal can prevent the call from being truncated by retransmitting the UMIC message to the target RNC.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate a thorough understanding of the present invention, the same reference numerals are used for the same means regardless of the number of the drawings.

3 is a diagram illustrating a configuration of a mobile communication system according to a preferred embodiment of the present invention.

3 illustrates a configuration of a mobile communication system according to 3GPP standards. The mobile communication system according to the present invention includes a Node B 300 and a Radio Network Controller (RNC) 300 belonging to a radio network subsystem (RNS) (MSC) 304, a GMSC (Gateway MSC) 306, a Serving GPRS Support Node (SGSN) 308, and a Gateway GPRS Support Node : GGSN, 310).

The Node B 300 sets a physical channel required for data exchange with the mobile terminal 312 according to the control information transmitted from the RNC 302, converts the data transmitted from the upper protocol to the radio environment, (312).

In addition, the Node B 300 transmits the data received from the mobile terminal 312 to the upper layer protocol of the RNC 302.

The RNC 302 controls the elements in the RNC to dynamically allocate radio resources of the UTRAN and performs switching to transmit data transmitted through the UTRAN to an appropriate node. The RNC 302 serves as an access point for all services provided through a core network (core network) including the exchange 304 and the SGSN 308.

The core network including the exchange 304 to the GGSN 310 performs functions such as call control, session management, and mobility management. The core network includes a circuit switching area and a packet switching area .

The exchange 304 included in the circuit switching area manages the circuit switching connection and manages the mobility management such as location information update (LAU), location registration, and paging, And the GMSC 306 serves as a path through which the circuit switched area is connected to the external network.

The SGSN 308 included in the packet switched area manages and supports the packet switched service to the UTRAN. In addition, it performs functions such as RAU (Routing Area Update) and Paging (page) to manage the mobility of the mobile communication terminal 312 provided with the packet switching service.

The GGSN 310 serves as a path for connecting the packet switched area to another packet switched network such as the Internet.

3, the UTRAN of the mobile communication system according to the present invention includes a Serving Radio Network Subsystem (SRNS) for managing dedicated radio resources allocated to a mobile terminal. In accordance with movement of the mobile terminal, A new path is set from the initial SRNS to another SRNS so that the SRNS from the source RNC 302 belonging to the initial SRNS to the target RNC 303 belonging to another SRNS Assignment is made.

In general, in order to prevent data loss in the SRNS relocation, the SRNS relocation is performed in an AM mode (Acknowledged Mode), whereby the source RNC 302 delivers information about unacknowledged data to the target RNC 303 side. At this time, the source RNC 302 transmits a sequence number for the unacknowledged data to the target RNC 303 side.

Control of delivery of the unacknowledged data and the serial number is performed between the PDCP entity of the source RNC 302 and the RRC entity, and the transfer of the data is performed by the source RNC 302 Between the RRC entity and the RRC entity of the target RNC 303. [

A UTRAN Mobility Information (UMI) procedure is performed between the target RNC 303 and the mobile terminal 312 when the RRC of the target RNC 303 receives information on the unacknowledged data or the like from the source RNC 302 do.

When a mobile terminal receives a network movement information message (hereinafter, referred to as 'UMI message') from the target RNC 303, the mobile terminal 312 transmits a network movement information confirmation message (UMI Confirm) Quot;).

At this time, according to the AM mode, the mobile terminal 312 must receive a response (ACK) for the UMIC message from the target RNC 303. According to a preferred embodiment of the present invention, when the mobile terminal 312 waits for an ACK reception, when an exception occurs, the call termination is prevented by retransmission of the UMIC.

In the AM mode, data to be transmitted and received between the mobile terminal 312 and the target RNC 303 must be synchronized with each other in the serial number (SN). In the exceptional case, when the serial numbers of data to be transmitted and received are not synchronized Or the data transmitted and received between the source RNC 302 and the mobile terminal 312 is not normally transmitted or received.

In this exceptional situation, the present invention enables the mobile terminal 312 to normally complete the SRNS relocation through retransmission of the UMIC message.

4 to 5 are views showing various examples of UMIC retransmission according to the present invention.

4 is a flowchart illustrating an example of UMIC retransmission according to the present invention.

Referring to FIG. 4, if the target RNC receives information about unacknowledged data from the source RNC, a UMI procedure is initiated between the target RNC and the mobile terminal (step 400).

At the start of the UMI procedure, the RRC entity of the target RNC 303 transmits the UMI message to the RRC entity of the mobile terminal (step 402).

At this time, the UMI message is transmitted via the signaling radio bearer (SRB 1).

The mobile station receiving the UMI message performs a process of initializing the RLC (step 404).

Step 404 is to initialize the RLC buffer and variables of the MT 312. The RRC of the MT terminates all the RBs except for the RBs 2 and initializes the RBs 2.

Thereafter, the RRC of the mobile station transmits an UMIC message to the RRC of the target RNC (step 406).

Here, the UMIC message is transmitted through the radio bearer (SRB 2) corresponding to the ID 2, and the serial number is 0 due to the RLC initialization.

After transmitting the UMIC, the mobile station waits for ACK reception for the UMIC message. Due to an exceptional situation, the RLC of the mobile station can receive an RLC RESET PDU from the RLC of the target RNC 303 (step 408 ).

Step 408 may be performed when the target RNC 303 fails to receive an ACK for the unacknowledged data transmitted from the source RNC 302, and so on.

For example, when the source RNC 302 transmits an MCM (Measurement Control Message) to the mobile terminal 312 and, in response to the reception of the ACK from the mobile terminal 312, The target RNC 303 can determine whether or not the ACK for the MCM is normally received.

In this case, when the target RNC 303 does not receive the ACK for the MCM from the mobile terminal 312, or when the NACK is received, or when the target RNC 303 initializes in the step 404, If the RLC RESET PDU is not received, the RLC RESET PDU is transmitted to the RLC entity of the MS 312 as in step 408.

The RLC of the mobile terminal 312 receives the AM data check failure message in the RRC (step 410).

According to the present invention, the RLC of the mobile station transmits a response message for RLC initialization to the RLC of the target RNC (step 412), and as a next step, the RRC of the mobile terminal 312, And retransmits the UMIC message to the RRC of the target RNC 303 (step 414).

In the UMIC retransmission, the RRC of mobile terminal 312 retransmits the UMIC message to the same radio bearer and sequence number as in step 406. [

In response to the UMIC retransmission, the RLC of the target RNC 303 transmits an ACK (RLC STATUS PDU) for the UMIC to the RLC of the MN 312 (step 416). Since the initialization of the RLC is performed in steps 408 to 412, the RLC of the target RNC transmits an ACK for the UMIC to the next sequence number (SN1) of the UMIC message in step 416. [

According to the present invention, the retransmission of the UMIC message can be repeatedly performed whenever steps 408 to 412 are performed according to the occurrence of an exception situation between the mobile terminal and the target RNC, that is, whenever an ACK to the UMIC is not normally received .

After receiving the ACK for the UMIC, the mobile terminal performs radio bearer setup for data transmission / reception (step 418), and then the UMI procedure is terminated (step 420).

FIG. 4 illustrates a process performed when the mobile station receives an RLC RESET PDU from the target RNC. However, when the mobile station transmits an RLC RESET PDU as shown in FIG. 5, the retransmission of the UMIC message can be performed.

Since steps 500 to 506 in FIG. 5 are the same as those in steps 400 to 406 in FIG. 4, detailed description thereof will be omitted.

The RLC of the target RNC 303 transmits an ACK for the UMIC message to the RLC of the MN 312 (step 508).

However, in step 510, the RLC of the target RNC may send an ACK with an invalid sequence number to the mobile terminal due to the unacknowledged data and the serial number transmitted from the source RNC.

For example, if the mobile station receives an ACK corresponding to the sequence number 9 from the target RNC, the mobile station waits for receipt of the ACK corresponding to the sequence number 1 according to the UMIC message transmission of the sequence number 0, (Step 510). Then, the RLC of the mobile station transmits an RLC RESET PDU to the RLC of the target RNC (step 512).

Meanwhile, the RLC of the target RNC 303 transmits a RLC initialization response message to the RLC of the MN 312 (step 514).

In the above description, when an ACK of an invalid sequence number is received from the target RNC, the mobile station transmits an RCL RESET PDU.

When the mobile station does not receive the ACK for the data transmitted to the source RNC 302 and fails to receive the ACK from the target RNC 303 according to the start of the SRNS reallocation procedure or receives a NACK from the target RNC The mobile terminal 312 transmits the RLC RESET PDU to the target RNC 303. [

According to the present invention, when receiving the RLC initialization response message as described above, the RRC of the mobile station retransmits the UMIC message to the RRC of the target RNC (step 516).

Since the RLC initialization has been performed in steps 508 to 514, the UMIC retransmission is performed through the same radio bearer and sequence number as in step 506. [

Then, the RLC of the target RNC transmits an ACK for the UMIC having a valid sequence number (SN 1) to the mobile terminal (step 518), and the mobile terminal performs a radio bearer setup process or the like (step 520). The UMI procedure is terminated through the above process (step 522).

According to the present invention, retransmission of an UMIC message can be repeated every time a normal ACK according to transmission of an UMIC message of a mobile station is not received or an exception condition requiring RLC initialization occurs, No arc truncation occurs even if initialization is performed.

6 is a flowchart illustrating a UMIC retransmission process of a mobile station according to the present invention.

FIG. 6 illustrates a process in a mobile terminal. Referring to FIG. 6, when an SRNS relocation is started (step 600), the mobile terminal receives a UMI message (step 602).

Upon receipt of the UMI message, the mobile station performs an RLC configuration procedure (step 604) and then transmits the UMIC message to the target RNC (step 606).

Thereafter, the MS determines whether a response message to the UMIC message is normally received (step 608). If the response message to the UMIC message is not received, the MS returns to step 606 and retransmits the UMIC message.

At this time, if the UMIC message is not received, the mobile station can perform the RLC initialization procedure with the target RNC.

Thereafter, if the response message to the UMIC message is normally received, the RLC scheduling process is performed (step 610), and the SRNS relocation procedure is terminated (step 612).

It will be apparent to those skilled in the relevant art that various modifications, additions and substitutions are possible, without departing from the spirit and scope of the invention as defined by the appended claims. The appended claims are to be considered as falling within the scope of the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an example of arc cutting according to the prior art; Fig.

Fig. 2 shows another example of arc cutting according to the prior art; Fig.

3 is a diagram illustrating a configuration of a mobile communication system according to a preferred embodiment of the present invention.

4 is a diagram illustrating an example of UMIC retransmission according to the present invention.

5 illustrates another example of UMIC retransmission according to the present invention.

6 is a flowchart illustrating a UMIC retransmission process of a mobile station according to the present invention.

Claims (14)

CLAIMS 1. A method for preventing call truncation at a mobile terminal in a Serving Radio Network Subsystem (SRNS) reassignment from a source RNC to a target RNC, (A) receiving a network movement information message from the target RNC; (B) performing an RLC configuration process; (C) transmitting a network movement information confirmation message to the target RNC; And (D) retransmitting the network movement information confirmation message to the target RNC when initialization of the RLC is performed after transmitting the network movement information confirmation message, Wherein the step (d) comprises: when the target RNC transmits and receives a message having an invalid sequence number between the mobile station and the target RNC, the target RNC transmits the unacknowledged data transmitted from the source RNC before the SRNS reallocation procedure When the mobile terminal does not receive a normal response message from the terminal or receives a negative acknowledgment (NACK) message, the mobile terminal transmits a normal response message from the target RNC to unacknowledged data transmitted to the source RNC before the start of the SRNS relocation procedure And a negative acknowledgment (NACK) message is received in the SRNS reallocation. The method according to claim 1, Wherein the step (d) is repeated every time the RLC initialization is performed. delete delete delete The method according to claim 1, Wherein the step (d) comprises retransmitting the network movement information confirmation message through the same radio bearer and the same sequence number as the step (c). The method according to claim 6, Wherein the RLC entity of the target RNC transmits a response message with the next sequence number of the network movement information confirmation message to the RLC entity of the mobile station. The method according to claim 1, Wherein the RLC initialization is performed at the RLC layer of the target RNC and the mobile station. A method for preventing call truncation in Serving Radio Network Subsystem (SRNS) reassignment in a target RNC, (A) transmitting a network movement information message to the mobile terminal upon initiation of the SRNS relocation procedure; (B) receiving a network movement information confirmation message from the mobile terminal; (C) receiving the network movement information confirmation message retransmitted by the mobile station when initialization of the RLC of the mobile station and the target RNC is performed; And (D) transmitting a response message having a next sequence number of the network movement information confirmation message to the mobile station. 10. The method of claim 9, Prior to step (c), a message having an invalid serial number is received from the mobile terminal, or a normal response message is not received from the mobile terminal for unacknowledged data transmitted from the source RNC before the start of the SRNS relocation procedure And transmitting an RLC initialization message to the mobile station if a negative acknowledgment (NACK) is received. When the SRNC is reallocated from the source RNC to the target RNC, receives a network movement information message from the RRC entity of the target RNC, transmits a network movement information confirmation message, and when RLC initialization is performed after transmitting the network movement information confirmation message, An RRC entity for retransmitting the network movement confirmation message to an RRC entity of the RNC; And If an exception occurs before receiving a response to the network movement information confirmation message, performs RLC and initialization of the target RNC, and transmits an RLC entity which receives a response of the retransmitted network movement information confirmation message from the RLC of the target RNC , ≪ / RTI &  The retransmission of the network movement information confirmation message is performed when the target RNC receives a message having an invalid sequence number between the mobile station and the target RNC, From the target RNC to the source RNC before the start of the SRNS relocation procedure when the mobile terminal does not receive a normal response message from the mobile station or receives a negative acknowledgment (NACK) message from the target RNC, And a case in which a response message is not received or a negative acknowledgment (NACK) message is received. delete delete A radio network controller for handling SRNS relocation comprising: An RRC entity for transmitting a network movement information message to the mobile terminal and receiving a network movement information confirmation message when the unacknowledged data and the serial number are received from the source RNC; And If an exception occurs before transmission of the response to the network movement information confirmation message, the UE performs initialization with the RLC of the mobile station, and transmits the network movement information confirmation message to the RRC entity, An RLC entity for transmitting a response to the network movement information confirmation message to the RLC entity of the mobile station, The retransmission of the network movement information confirmation message is performed when a message having an invalid sequence number is transmitted / received between the mobile station and the target RNC, the retransmission of the unacknowledged data transmitted from the source RNC before the start of the SRNS reallocation procedure When a normal response message is not received from the mobile station or a negative acknowledgment (NACK) message is received, the mobile station transmits a normal response message from the target RNC to the unacknowledged data transmitted to the source RNC before the start of the SRNS relocation procedure And a negative acknowledgment (NACK) message is received from the radio network controller.

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