KR20090063089A - How to manage terminal capabilities - Google Patents

Abstract

The present invention relates to a method for managing terminal capability in a wireless communication system. More particularly, the present invention relates to a method for a mobility management entity (MME) of a network in a wireless communication system to manage terminal capability, the method comprising: receiving a first status indicator regarding terminal capability; Determining whether a predetermined condition is satisfied by using the first status indicator, and selectively transmitting the terminal capability to a base station or requesting the base station to acquire the terminal capability according to whether the predetermined condition is satisfied. It relates to a terminal capability management method comprising the step.

Description

How to manage device capabilities {METHOD OF MANAGING USER EQUIPMENT CAPABILITIES}

The present invention relates to a wireless communication system, and more particularly, to a method for managing terminal capability in a wireless communication system.

3rd Generation Partnership Project (3GPP) mobile communication systems based on Wideband Code Division Multiple Access (WCDMA) radio access technology are widely deployed around the world. High Speed Downlink Packet Access (HSDPA), which can be defined as the first evolution of WCDMA, provides 3GPP with a highly competitive wireless access technology in the mid-term future. However, as the demands and expectations of users and operators continue to increase, and the development of competing wireless access technologies continues to progress, new technological evolution in 3GPP is required to be competitive in the future. Reduced cost per bit, increased service availability, flexible use of frequency bands, simple structure and open interface, and adequate power consumption of the terminal are required.

In the 3GPP LTE system, EMM-REGISTERED (EPS Mobility Management-REGISTERED) and EMM-DEREGISTERED states are defined to manage mobility of the UE. The state is applied to a mobility management entity (MME) of a terminal and a network. The UE is initially in the EMM-DEREGISTERED state and performs a process of registering in the corresponding network through an 'Initial Attach' procedure to access the network. If the 'attach' procedure is successfully performed, the UE and the MME are in the EMM-REGISTERED state.

In order to manage a signaling connection between the UE and the EPC, an EPS Connection Management (ECM) -IDLE and an ECM-CONNECTED state are defined. The state is applied to the terminal and the MME. The UE in the ECM-IDLE state becomes an ECM-CONNECTED state when it establishes an RRC connection with the E-UTRAN. The MME in the ECM-IDLE state becomes the ECM-CONNECTED state when it establishes an S1 connection with the E-UTRAN. When the terminal is in the ECM-IDLE state, the E-UTRAN does not have context information of the terminal. Accordingly, the UE in the ECM-IDLE state performs a terminal-based mobility related procedure such as cell selection or cell reselection without receiving a command from the network. On the other hand, when the terminal is in the ECM-CONNECTED state, the mobility of the terminal is managed by the network. In the ECM-IDLE state, if the position of the terminal is different from the position known by the network, the terminal informs the network of the corresponding position of the terminal through a tracking area update procedure.

When the connection is established between the base station and the terminal, the base station needs capability information of the terminal in order to set radio resources to the terminal. In addition, the network needs the capability information of the terminal in order to manage the terminal (eg, mobility support, etc.). The capability information of the terminal may include information for managing / operating a radio resource for the terminal (power control related information, code resource information, encryption related information, PDCP related capability, and the like). In addition, the capability information of the terminal may include Radio Access Technology (RAT) information supported by the terminal.

1 shows that the terminal capability is delivered in the process of the terminal performing the 'attach'. The detailed process is as follows.

1. The UE performs an RRC connection establishment procedure. If the RRC connection establishment is successful, the terminal transmits an RRC CONNECTION COMPLETE message to the base station. The terminal includes a NAS 'Attach Request' message in the RRC message.

2. After the base station receives the RRC message, the base station delivers an S1 control message (Initial UE Message) including the NAS message (Attach Request) to the MME.

3. The MME, in response to the 'Attach Request' message, transmits an S1 control message (Initial Context Setup Request) including 'Attach Accept' to the base station.

4. The base station receives an 'Attach Accept' message from the MME.

5. The base station performs Initial Security Activation.

6. The base station receives capability information from the terminal through the RRC procedure.

7. The base station performs the RRC connection reconfiguration procedure using the received terminal capability information to obtain the latest terminal capability from the terminal.

8. The base station transmits an S1 control message (Initial Context Setup Response) including the terminal capability information to the MME.

As shown in FIG. 1, conventionally, whenever a terminal establishes an RRC connection, the terminal transmits the capability of the terminal to the network. However, with the advent of terminals supporting various wireless access technologies and the complexity of terminal functions, capability information of terminals is also increasing. Considering the fact that the capability of the terminal does not change frequently and the size of the capability information of the terminal is large, a method of sending a considerable amount of information to the network every time an RRC connection is made causes a waste of radio resources.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a method for efficiently managing the terminal capability in a network of a wireless communication system.

Another object of the present invention is to provide a method capable of reducing the amount of radio resources required for the delivery of terminal capabilities.

Another object of the present invention is to provide a method for delivering the latest terminal capability to the network only when the terminal capability is changed.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

In one aspect of the present invention, a method of managing a terminal capability by a Mobility Management Entity (MME) of a network in a wireless communication system, the method comprising: receiving a first status indicator regarding terminal capability; Determining whether a predetermined condition is satisfied using the first status indicator, and optionally transmitting the terminal capability to a base station or requesting the base station to acquire the terminal capability according to whether the predetermined condition is satisfied. Provided is a terminal capability management method comprising a.

In another aspect of the present invention, a method for acquiring terminal capability by a base station in a wireless communication system, the method comprising: receiving a status indicator regarding the terminal capability from the terminal, and the status indicator is a mobility management entity of a network. (B) delivering to the Mobility Management Entity (MME), and receiving the terminal capability from the MME or obtaining a terminal capability from the terminal at the request of the MME. A method is provided.

According to embodiments of the present invention has the following effects.

First, it is possible to reduce the radio resources required to deliver the terminal capability.

Second, since the terminal transmits the capability information only when the terminal capability is changed, the overhead of the terminal operation can be reduced.

Third, the efficiency of network resource utilization can be improved by reducing the transmission of terminal capability information between networks.

Fourth, the operation of the network entity is limited to messages directly related to the layer to preserve the independence of the AS layer and the NAS layer.

Effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

The construction, operation, and other features of the present invention will be readily understood by the embodiments of the present invention described with reference to the accompanying drawings. The embodiments described below are examples in which technical features of the present invention are applied to an Evolved Universal Mobile Telecommunications System (E-UMTS).

2 shows a network structure of an E-UMTS. The E-UMTS system is an evolution from the existing WCDMA UMTS system and is currently undergoing basic standardization work in the 3rd Generation Partnership Project (3GPP). E-UMTS is also called a Long Term Evolution (LTE) system. For details of technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of the "3rd Generation Partnership Project; Technical Specification Group Radio Access Network", respectively.

Referring to FIG. 2, an E-UMTS is largely composed of an access gateway (AG) located at an end of a user equipment (UE), a base station, and an network (E-UTRAN) and connected to an external network. Typically, a base station can transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service. The AG may be divided into a part that handles user traffic processing and a part that handles control traffic. A new interface can be used to communicate with each other between the AG for handling new user traffic and the AG for controlling traffic. One or more cells exist in one eNB. An interface for transmitting user traffic or control traffic may be used between eNBs. CN (Core Network) may be configured with a network node for the user registration of the AG and the UE. An interface for distinguishing between E-UTRAN and CN may be used. AG manages the mobility of the terminal in units of a tracking area (TA). The TA is composed of a plurality of cells, and when the UE moves from one TA to another, the AG notifies the AG of the change of the TA.

3 shows a network structure of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The E-UTRAN system is an evolution from the existing UTRAN system. The E-UTRAN consists of base stations, and eNBs are connected via an X2 interface. The eNB is connected to the terminal through a wireless interface, and is connected to the Evolved Packet Core (EPC) through the S1 interface.

4 and 5 illustrate a control plane and a user plane (U-Plane, User-Plane) structure of a radio interface protocol between a UE and an E-UTRAN based on 3GPP radio access network standards, respectively. Indicates. The air interface protocol consists of a physical layer, a data link layer, and a network layer horizontally, and vertically a user plane and control signal for data information transmission. (Signaling) It is divided into control plane for transmission. The protocol layers of FIGS. 4 and 5 are based on the lower three layers of the Open System Interconnection (OSI) reference model, which are well known in communication systems, based on L1 (first layer), L2 (second layer), and L3 (The third layer).

The control plane refers to a path through which control messages used by the terminal and the network to manage a call are transmitted. The user plane refers to a path through which data generated at an application layer, for example, voice data or Internet packet data, is transmitted. Hereinafter, each layer of the control plane and the user plane of the radio protocol will be described.

The physical layer, which is the first layer, provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to the upper layer of the medium access control layer through a transport channel. Data moves between the medium access control layer and the physical layer through the transport channel. Data moves between the physical layer between the transmitting side and the receiving side through the physical channel. The physical channel is modulated by an orthogonal frequency division multiplexing (OFDM) scheme and utilizes time and frequency as radio resources.

The medium access control (MAC) layer of the second layer provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The functionality of the RLC layer may be implemented as a functional block inside the MAC. In this case, the RLC layer may not exist. The PDCP (Packet Data Convergence Protocol) layer of the second layer performs a header compression function to reduce unnecessary control information in order to efficiently transmit an IP packet such as IPv4 or IPv6 over a narrow bandwidth interface. .

The radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration, re-configuration, and release of radio bearers (RBs) are performed. It is in charge of controlling logical channels, transport channels and physical channels. RB means a service provided by the second layer for data transmission between the UE and the E-UTRAN. The RRC layer exchanges RRC messages between the terminal and the network. If there is an RRC connected (RRC Connected) between the RRC layer of the terminal and the RRC layer of the wireless network, the terminal is in the RRC connected mode (Connected Mode), otherwise it is in the RRC idle mode (Idle Mode).

The non-access stratum (NAS) layer above the RRC layer performs functions such as session management and mobility management. The NAS layer is present in a mobility management entity (MME) of a terminal and a network.

MME is a key control-node in LTE access networks. The MME is responsible for tracking and paging processes for the terminal in the idle state. The MME is also involved in the radio bearer activation / deactivation process and is responsible for selecting a Serving Gateway (SGW) for UEs during 'Initial Attach' or during intra-LTE handovers including core network relocation. Together. The MME is responsible for terminal authentication through interaction with a Home Subscriber Server (HSS). NAS signaling is terminated in the MME, the MME is responsible for generating a temporary identifier and assigning to the terminal. The MME checks whether the UE has a right to camp on a PLMN (Public Land Mobile Network) of the service provider. The MME is the endpoint for encryption / integrity protection for NAS signaling in the network and is responsible for security key management. The MME provides control fairness for mobility between LTE and 2G / 3G access networks.

One cell constituting the eNB is set to one of the bandwidth, such as 1.25, 2.5, 5, 10, 20Mhz to provide a downlink or uplink transmission service to multiple terminals. Different cells may be configured to provide different bandwidths.

The downlink transmission channel for transmitting data from the network to the UE includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a downlink shared channel (SCH) for transmitting user traffic or control messages. have. Traffic or control messages of a downlink multicast or broadcast service may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the terminal to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or a control message.

It is located above the transport channel, and the logical channel mapped to the transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and an MTCH (multicast). Traffic Channel).

Embodiment: Delivery / Recycling of Terminal Capability Information

Since the size of the terminal capability information is not small, providing the information to the network whenever the terminal changes from ECM-IDLE to ECM-CONNECTED causes a lot of overhead of the radio section. Accordingly, the present invention proposes a mechanism for storing capability information of a terminal in a network and then recycling it when necessary. For example, when the terminal is changed from ECM-IDLE to ECM-CONNECTED, the capability information of the terminal may be recycled. The capability information of the terminal may be stored in a mobility management entity (MME) in a network. Therefore, when the terminal is changed from ECM-IDLE to ECM-CONNECTED, if the MME has the terminal capability information, the MME may provide the terminal capability information to the base station instead of the terminal.

In order to recycle the terminal capability stored in the network, a mechanism for determining whether the stored terminal capability is up-to-date is necessary in consideration of the characteristic that the terminal capability can be changed. As an example of the mechanism, a status indicator regarding terminal capability may be used. The state indicator is set for each terminal capability by the terminal. That is, the same state indicator means that the terminal capability information is the same. Therefore, if the status indicator of the terminal and the status indicator of the network is the same, the terminal capability information in the network can be regarded as the latest information. For convenience, the status indicator of the terminal is referred to as a first status indicator, and the status indicator of the network is referred to as a second status indicator. The status indicator may be stored in the MME. In one embodiment, the status indicator may be a value tag. That is, a method of changing the value of the value tag whenever the capability of the terminal changes can be used. As an example, the terminal delivers a value tag to the network whenever performing a procedure requiring terminal capability in the network. An example of a procedure for which the terminal capability is required is a 'Service Request' procedure. In a procedure requiring terminal capability, the network compares a value tag (first value tag) received from the terminal with a value tag (second value tag) stored in the network. If the first value tag and the second value tag are different, the network determines that the stored terminal capability information is not the latest information.

As described above, the capability information and the status indicator of the terminal may be stored in the MME, but comparing the status indicator and determining whether to recycle the terminal capability information stored in the network may be performed in the base station and the MME requiring the terminal capability. . The base station requiring the terminal capability may be a serving base station. An example of the process of performing the above procedure is as follows.

Base station:

     1. Receive the NAS first status indicator included in the RRC message from the terminal.

     2. Read the first status indicator from a NAS container.

     3. Receive the terminal capability information and the second status indicator from the MME.

    4-1. If the first status indicator and the second status indicator are the same, the terminal capability information received from the MME is used.

    4-2. If the first status indicator and the second status indicator are different, the terminal capability information received from the MME is discarded and the terminal requests the capability information.

-MME:

    1. Receive a NAS first status indicator from the terminal.

    2-1. If the first status indicator and the second status indicator in the MME are the same, the stored terminal capability information is transmitted to the base station.

    2-2. If the first status indicator and the second status indicator are different, request the terminal capability information from the base station.

As described above, determining whether the terminal capability information stored in the MME is up-to-date information and determining whether to recycle the information may be performed at either the base station or the MME. However, it is preferable to perform the above-described procedure in the MME from the following point of view.

First, if the base station determines whether the terminal capability information stored in the MME is up-to-date information, the MME must deliver the terminal capability information to the base station in a situation in which it does not know whether the terminal capability information is the latest information. Therefore, if the base station determines that the information is not the latest information after receiving the terminal capability information from the MME, the result is a waste of S1 interface resources.

On the other hand, if the MME determines whether the terminal capability information is the latest information, the MME provides the terminal capability information to the base station only when it is determined that the stored terminal capability information is the latest information. Therefore, it is possible to eliminate the problem of wasting the S1 interface resources to transmit the terminal capability information that is not useful.

Second, if the base station determines whether the terminal capability information stored in the MME is up-to-date information, the base station should read the status indicator in the NAS container included in the RRC message received from the terminal to compare the status indicator. Checking the contents of the NAS container between the terminal and the MME by the base station, which is a network entity related to the AS layer, undermines the independence of the AS layer and the NAS layer.

On the other hand, if the MME determines whether the capability information of the terminal is up-to-date information, the MME does not need to deliver a status indicator regarding the terminal capability information to the base station. Therefore, there is no problem of inefficiency that the base station must read the status indicator in the NAS container, and the independence of the AS layer and the NAS layer is ensured.

Hereinafter, a method of transmitting / recycling terminal capability information according to an embodiment of the present invention mainly on an MME will be described in more detail. As a representative example, only a case in which the terminal performs 'Attach' and 'Service Request' will be described in detail, but the present invention is not limited to the case where the terminal performs the 'Attach' and 'Service Request' procedures. The present invention can be applied to other procedures in which an entity of a network such as a base station can receive (download) the capability of the terminal from the MME.

Delivery of terminal capability information at 'attach'

When the terminal performs the 'attach' procedure, the capability information for the terminal is often invalid or does not exist in the MME. Therefore, when performing the 'Attach' procedure, even if the capability information of the terminal is stored in the MME, the terminal may ignore the capability information of the terminal and receive the latest capability information from the corresponding terminal. Through this, the MME may manage / maintain the latest information on the terminal. More specifically, in the process of performing an 'attach' procedure, there may be the following cases.

Case 1: If the terminal does not transmit the status indicator, the capability information for the terminal may be already stored in the MME. Although the existing state indicator is stored in the MME, it is assumed that the MME does not have the latest capability information of the terminal in consideration of the UE performing the 'attach' procedure. Accordingly, the MME requests capability information of the terminal from the base station and stores capability information received from the terminal.

Case 2: When the terminal transmits the status indicator, the capability information for the terminal may be already stored in the MME. The MME assumes that the terminal does not have the latest capability information in consideration of the fact that the terminal performs the 'attach' procedure even if the stored state indicator matches the received state indicator. Therefore, the MME replaces the stored status indicator with a status indicator received from the terminal. Thereafter, the MME requests the base station for capability information, and stores the capability information received from the terminal through the base station.

Case 3: When the terminal transmits the status indicator, the terminal information for the terminal may not be stored in the MME. Since the MME has no capability information of the terminal, the MME requests the terminal capability information from the base station and stores the capability information received from the terminal.

Hereinafter, referring to FIGS. 6 and 7, a method of delivering capability information of a terminal when performing an 'attach' procedure according to an embodiment of the present invention will be described in detail.

Referring to FIG. 6, an 'Initial Attach' procedure may be performed as follows.

1. The UE performs an RRC connection establishment procedure. The RRC connection establishment procedure may be performed through a random access process. For example, the terminal transmits a RACH preamble, and the base station allocates an uplink resource to the terminal as a response to the preamble. Thereafter, the terminal transmits an 'RRC CONNECTION REQUEST' message to the base station, and the base station transmits a 'RRC CONNECTION SETUP' message to the terminal. If the RRC connection establishment is successful, the terminal transmits a 'RRC CONNECTION COMPLETE' message to the base station. The terminal includes the NAS 'Attach Request' in the 'RRC CONNECTION COMPLETE' message.

2. The base station transmits the first S1 control message including the NAS 'Attach Request' to the MME through the S1 interface. The first control message may be an 'Initial Context Setup Request' message or a corresponding control message.

3. The MME, in response to the NAS 'Attach Request', transmits a second S1 control message including the NAS 'Attach Accept' to the base station. The second S1 control message may be an 'Initial Context Setup Request' or a corresponding message.

4. The base station receives the second S1 control message including the NAS 'Attach Accept' from the MME.

5. The base station may transmit a message including the NAS 'Attach Accept' received from the MME to the terminal. The message is for delivering a NAS message from the MME to the terminal, and may be omitted if the NAS 'Attach Accept' is delivered to the terminal through another process. The message may be a 'DL INFORMATION TRANSFER' message. Thereafter, the base station performs an Initial Security Activation procedure. Specifically, the base station delivers a 'SECURITY MODE COMMAND' message to the terminal. After activating the security according to the message, the terminal transmits a 'SECURITY MODE COMPLETE' message to the base station.

6. Since the base station has not received the information about the terminal capability from the MME, the base station receives the capability information from the terminal through an RRC procedure (UE Capability Transfer RRC procedure) for delivering the terminal capability. Specifically, the base station transmits a 'UE CAPABILITY ENQUIRY' message requesting the latest capability of the terminal to the terminal. The terminal transmits a 'CAPABILITY INFORMATION' message including the latest terminal capability information to the base station in response to the message. The 'CAPABILITY INFORMATION' message may include a value tag related to the terminal capability.

7. The base station performs an RRC connection reconfiguration procedure by using the received terminal capability information. Specifically, the base station sets up a radio bearer and transmits a 'RRC CONNECTION RECONGIGURATION' message indicating the RRC connection reconfiguration to the terminal. If, in step 5, the 'DL INFORMATION TRANSFER' message is delivered to the NAS 'Accept Attach' terminal, the RRC message does not include the NAS 'Accept Attach'. On the other hand, if the 'DL INFORMATION TRANSFER' message is not transmitted in step 5, the base station includes the NAS 'Attach Accept' received from the MME in the 'RRC CONNECTION RECONGIGURATION'. After the UE completes the RRC connection reconfiguration, the terminal transmits a 'RRC RECONFIGURATION COMPLETE' message to the base station. The RRC message may include a NAS 'Attach Complete' message for notifying the MME that the 'attach procedure has been successfully performed'.

8. The base station transmits the third S1 control message including the capability information received from the terminal and the NAS 'Attach Complete' message to the MME through the S1 interface. The third S1 control message may be an 'Initial Context Setup Response' message or a corresponding control message as a response to the second S1 control message received from the MME. The third control message includes a NAS 'Attach Complete message transmitted from the terminal.

9. The MME regards the received capability information of the terminal as the latest information and stores it.

10. The MME considers and stores the value tag included in the capability information of the terminal received from the base station as a value tag corresponding to the latest capability of the terminal.

In step 3, the capability for the terminal and a value tag thereof may be already stored in the MME. The MME considers that the terminal performs 'Initial Attach' even if the existing value tag is stored, and considers that the terminal capability information in the MME is not up to date. Accordingly, the MME acquires the latest capability information of the terminal and a value tag corresponding to the capability information through the processes 5 to 10.

In addition, processes 5 and 6 may be changed in order depending on whether or not to encrypt the RRC message associated with the 'UE Capability transfer' procedure.

7 illustrates performing an 'Initial Attach' procedure according to another embodiment of the present invention. The procedure of FIG. 7 is basically the same as the procedure illustrated in FIG. 6 except that the terminal separately transmits a value tag regarding the terminal capability information at the beginning of the procedure. Referring to FIG. 7, processes 1 to 3 of FIG. 6 may be modified as follows to initially transmit a value tag to an MME. In addition, step 10 is omitted.

1. The terminal performs an RRC connection setup procedure. If the RRC connection establishment is successful, the terminal transmits a 'RRC CONNECTION COMPLETE' message to the base station. The terminal includes a NAS value tag relating to NAS 'Attach Request' and the latest capability in the RRC message.

2. The base station transmits the S1 control message including the NAS 'Attach Request' and the NAS value tag to the MME through the S1 interface.

3. The MME, in response to the NAS 'Attach Request', transmits a first S1 control message including the NAS 'Attach Accept' to the base station through the S1 interface. In addition, the MME stores the value tag and regards it as a value tag related to the latest terminal capability obtained through the process 4-9.

In step 3, capability information for the corresponding UE may be stored or not stored in the MME. In consideration of the 'Initial Attach' procedure, the MME requests the base station for the latest terminal capability information regardless of whether the terminal capability is present or not.

6 and 7, the terminal capability and the value tag are shown to be stored together. This is only to show the relationship between the terminal capability and the value tag, but does not mean that the terminal capability and the value tag are stored at the same time. The terminal capability and the value tag may be stored at the same time or different times according to the implementation.

Transfer / reuse of terminal capability information at 'Service Request'

When the terminal performs a 'Service Request' procedure for the purpose of transmitting a response to the paging of the network or data generated from the user to the network, the capability information of the terminal is generally present in the MME. When the base station needs to know the capabilities of the terminal, if the MME has the latest information on the terminal capabilities, the base station can download and use the capabilities of the terminal from the MME. If the capability information of the terminal of the MME is not the latest information or the MME does not have the capability information of the terminal at all, the MME requests the base station for the latest information on the terminal capability. As an example, when the MME receives a value tag (first value tag) from the terminal, the MME determines whether a stored value tag (second value tag) exists. If the second value tag exists, it is determined whether the first value tag and the second value tag are the same. If any of the above conditions are not satisfied, the MME determines that the stored terminal capability is not the latest information. The MME replaces the second value tag with the first value tag and requests the base station for the latest information about the terminal capability. In response to the request, the base station acquires the latest terminal capability from the terminal and performs a procedure for delivering to the MME. Specifically, the base station receiving the request from the MME transmits a command to transmit the capability information to the terminal. The terminal receiving the command from the base station transmits its capability information to the base station. The base station delivers the capability information received from the terminal to the MME. The MME regards the capability information as the latest information about the terminal and stores it. In some cases, the capability information may include a value tag related to the capability information. In this case, the MME stores the value tag included in the terminal capability together with the latest capability information.

Hereinafter, a method of performing a 'Service Request' procedure according to an embodiment of the present invention will be described in detail with reference to FIGS. 8 to 10.

8 illustrates a process of performing a 'Service Request' procedure when the MME has the latest capability information of the terminal. In the process, the capability information of the terminal stored in the MME is transferred to the base station and recycled. The detailed process is as follows.

1. The terminal performs an RRC connection setup procedure. If the RRC connection establishment is successful, the terminal transmits a 'RRC CONNECTION COMPLETE' message to the base station. The terminal includes a NAS 'Service Request' message and a NAS value tag (first value tag) for the terminal capability in the RRC message.

2. After receiving the RRC message, the base station delivers the NAS 'Service Request' message and the NAS value tag to the MME using the first S1 control message. The S1 control message may be an 'Initial UE Message' or a corresponding control message.

3. The MME, having received the NAS 'Service Request' from the base station, determines whether the terminal capability is recyclable when there is a stored terminal capability. That is, the MME determines whether there is a stored value tag (second value tag) for the capability of the terminal, and compares the first value tag with the second value tag. Since the first value tag and the second value tag are the same, the MME considers the stored terminal capability to be the latest information. Thereafter, the MME downloads the stored terminal capability information to the base station through the second S1 control message. The second S1 control message may be an 'Initial Context Setup Request' or a corresponding control message.

4. The base station receives the second S1 control message.

5. The base station performs an initial security activation procedure. At this time, capability information of the terminal downloaded from the MME may be utilized.

6. The base station performs the RRC connection reconfiguration procedure using the terminal capability information downloaded from the MME.

7. The base station sends a third S1 control message to the MME via the S1 interface in response to the second S1 control message. The third S1 control message may be an 'Initial Context Setup Complete' or a corresponding control message.

9 and 10 illustrate a process of performing a 'Service Request' procedure when the MME does not have the latest capability information of the terminal. In the process, the capability information of the terminal stored in the MME is not recycled. The detailed process is as follows.

1. The terminal performs an RRC connection setup procedure. If the RRC connection establishment is successful, the terminal transmits a 'RRC CONNECTION COMPLETE' message to the base station. The terminal includes a NAS value tag (first value tag) for the NAS 'Service Request' and the terminal capability in the RRC message.

2. After receiving the RRC message, the base station delivers the NAS 'Service Request' message and the NAS value tag to the MME using the first S1 control message. The first S1 control message may be an 'Initial UE Message' or a corresponding control message.

3. The MME, having received the NAS 'Service Request' from the base station, determines whether the terminal capability is recyclable when there is a stored terminal capability. That is, the MME determines whether there is a stored value tag (second value tag) for the capability of the terminal and compares the first value tag with the second value tag. Since the first value tag and the second value tag are different, the MME considers that the stored terminal capability is not the latest information. Accordingly, the MME requests the base station for the latest terminal capability information corresponding to the first value tag.

The MME may request the capability information of the terminal using the following method.

i) The second S1 control message transmitted to the base station through the S1 interface may include a control command for requesting the terminal capability information. The second S1 control message may be an 'Initial Context Setup Request' message or a corresponding control message. The control command for requesting the terminal capability information may be 'UE CAPABILITY REQUEST'. The base station receiving the control command receives the latest capability information from the terminal, and transfers the capability information to the MME (FIG. 9).

ii) UE capability and 'UE CAPABILITY REQUEST' may not be included in the second S1 control message transmitted to the base station through the S1 interface. The second S1 control message may be an 'Initial Context Setup Request' message or a corresponding control message. That is, requesting the base station the latest capability information of the terminal may be indicated by the absence of the terminal capability and the 'UE Capability Request' in the S1 control message. The base station receiving the second S1 control message receives the latest capability information from the terminal, and then transfers the capability information to the MME (FIG. 10).

4. The base station receives the second S1 control message from the MME.

5. The base station performs an initial security activation procedure.

6. Since the base station is requested to transmit the latest capability information of the terminal from the MME to the MME, the base station receives the capability information from the terminal through an RRC procedure (UE Capability transfer RRC procedure) for delivering the terminal capability.

7. The base station performs the RRC connection reconfiguration procedure using the terminal capability information received from the terminal.

8. The base station includes the capability information of the terminal received from the terminal in the third S1 control message and transmits it to the MME. The third S1 control message may be an 'Initial Context Setup Complete' or a corresponding control message as a response to the second S1 control message received from the MME.

9. The MME stores the capability information of the received terminal and regards the information as the latest capability information for the terminal.

10. The MME stores the value tag received with the NAS 'Service Request' message from the base station and considers the value tag corresponding to the latest capability information of the terminal.

In relation to step 10, a value tag may be included in the capability information of the terminal received from the base station. In this case, the MME ignores the value tag received with the 'Service Reqeuset' message and stores the value tag included in the capability information of the terminal as a value tag corresponding to the latest capability information of the terminal.

Also, the processes 6 and 7 may be changed in order depending on whether or not the RRC message related to the 'UE Capability transfer' procedure is encrypted.

8 and 10, the terminal capability and the value tag are shown to be stored together. This is only to show the relationship between the terminal capability and the value tag, but does not mean that the terminal capability and the value tag are stored at the same time. The terminal capability and the value tag may be stored at the same time or different times according to the implementation.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

In this document, embodiments of the present invention have been mainly described based on data transmission / reception relations between a terminal and a base station. Certain operations described in this document as being performed by a base station may in some cases be performed by an upper node thereof. That is, it is obvious that various operations performed for communication with the terminal in a network including a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. A 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the term "terminal" may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

The present invention can be applied to a method for managing terminal capability in a wireless communication system. In more detail, the present invention can be applied to a method in which a mobility management entity (MME) of a network manages a capability of a terminal in a wireless communication system.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.

1 illustrates a method of delivering terminal capability at network connection.

2 shows a network structure of an E-UMTS.

3 is a schematic configuration diagram of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN).

4 and 5 illustrate a control plane and a user plane structure of a radio interface protocol between a UE and an E-UTRAN, respectively.

6 illustrates a method of delivering terminal capability when performing 'Initial Attach' according to an embodiment of the present invention.

7 illustrates a method of delivering terminal capability when performing 'Initial Attach' according to another embodiment of the present invention.

8 illustrates a method of managing terminal capabilities when performing a 'Service Request' according to an embodiment of the present invention.

9 illustrates a method of managing terminal capabilities when performing a 'Service Request' according to another embodiment of the present invention.

10 illustrates a method of managing terminal capability when performing a 'Service Request' according to another embodiment of the present invention.

Claims (15)

A method of managing mobility of a terminal by a mobility management entity (MME) of a network in a wireless communication system, Receiving a first status indicator relating to the terminal capability; Determining whether a predetermined condition is satisfied using the first state indicator; Selectively transmitting the terminal capability to a base station or requesting the base station to obtain the terminal capability according to whether the predetermined condition is satisfied. The method of claim 1, And the first state indicator is a value tag for a current capability of the terminal. The method of claim 1, And the first status indicator is received using an S1 control message. The method of claim 1, The S1 control message is 'Initial UE Message', characterized in that, the terminal capability management method. The method of claim 3, When the 'Attach Request' is included in the S1 control message, requesting the base station to acquire the terminal capability without determining whether the predetermined condition is satisfied. The method of claim 3, When the 'Service Request' is included in the S1 control message, it is determined whether the predetermined condition is satisfied, terminal capability management method. The method of claim 1, And whether the predetermined condition is satisfied is determined by whether the first status indicator and the second status indicator regarding the terminal in the MME are the same. The method of claim 1, And when the predetermined condition is satisfied, delivering the capability of the terminal in the MME to the base station. The method of claim 1, And if the predetermined condition is not satisfied, requesting the base station to acquire the terminal capability. The method of claim 1, The method of claim 1, wherein the transmitting of the capability or requesting the capability of the terminal is performed using an S1 control message. The method of claim 10, The S1 control message is 'Initial Context Setup Request', characterized in that the terminal capability management method. The method of claim 10, Requesting to obtain the terminal capability is indicated by a 'UE Capability Request' included in the S1 control message. The method of claim 10, Requesting to obtain the terminal capability is indicated by the absence of a capability related to the terminal and a 'UE Capability Request' in the S1 control message. The method of claim 1, And requesting the base station to acquire the terminal capability, storing the terminal capability received from the base station and the first status indicator. In the method for obtaining a capability of the terminal by the base station in a wireless communication system, Receiving a status indicator regarding the capability of the terminal from the terminal; Delivering the status indicator to a Mobility Management Entity (MME) in a network; And Receiving the capability of the terminal from the MME, or performing a process for acquiring the capability from the terminal according to the request of the MME, terminal capability acquisition method.

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