KR101467795B1 - Method of managing user equipment capabilities - Google Patents

Abstract

The present invention relates to a method for managing terminal capabilities in a wireless communication system. More particularly, the present invention relates to a method for managing a terminal capability of a Mobility Management Entity (MME) of a network in a wireless communication system, comprising the steps of: receiving a first status indicator Determining whether a predetermined condition is satisfied using the first status indicator, and transmitting the terminal capability to a base station selectively according to whether the predetermined condition is satisfied or requesting the base station to acquire the terminal capability To a terminal capability management method.

Description

[0001] METHOD OF MANAGING USER EQUIPMENT CAPABILITIES [0002]

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

A 3rd Generation Partnership Project (3GPP) mobile communication system based on WCDMA (Wideband Code Division Multiple Access) radio access technology is widely deployed all over the world. HSDPA (High Speed Downlink Packet Access), which can be defined as the first evolutionary phase of WCDMA, provides 3GPP with highly competitive wireless access technology in the mid-term future. However, since the development of wireless access technology that continues to increase and compete with the requirements and expectations of users and operators continues, development of new technologies in 3GPP is required for future competitiveness. Cost reduction per bit, increased service availability, use of flexible frequency band, simple structure and open interface, and proper power consumption of terminal.

In the 3GPP LTE system, an EMM-REGISTERED (EPS Mobility Management-REGISTERED) and an EMM-DEREGIEDED state are defined to manage the mobility of a UE. The status is applied to a Mobility Management Entity (MME) of the UE and the network. The terminal is initially in the EMM-DEREGISTERED state and performs the process of registering with the network through the 'Initial Attach' procedure to access the network. When the 'Attach' procedure is successfully performed, the terminal and the MME enter the EMM-REGISTERED state.

ECM (EPS Connection Management) -IDLE and ECM-CONNECTED states are defined to manage the signaling connection between the terminal and the EPC. This state is applied to the terminal and the MME. The UE in the ECM-IDLE state enters the ECM-CONNECTED state when it makes an RRC connection with the E-UTRAN. The MME in the ECM-IDLE state enters the ECM-CONNECTED state when it makes 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. Therefore, the terminal in the ECM-IDLE state performs terminal-based mobility-related procedures such as cell selection or cell reselection without receiving commands 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. If the location of the terminal is different from the location known by the network in the ECM-IDLE state, the terminal informs the network of the corresponding location of the terminal through a tracking area update procedure.

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

FIG. 1 shows that the terminal capability is transferred in the process of 'Attach' by the terminal. The detailed procedure is as follows.

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

2. After receiving the RRC message, the BS transmits an Initial UE message including the NAS message (Attach Request) to the MME.

3. As a response to the 'Attach Request' message, the MME sends an Initial Context Setup Request message containing 'Attach Accept' to the base station.

4. The base station receives the '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 acquires the latest terminal capability from the terminal by performing the RRC connection reconfiguration procedure using the received terminal capability information.

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

As shown in FIG. 1, each time a terminal establishes an RRC connection, the terminal transmits its capability to the network. However, since terminals supporting various wireless access technologies have emerged and the terminal functions have become complicated, the capability information of the terminals is also increasing. Considering that the capability of the UE does not change frequently and the size of the capability information of the UE is large, a method of sending a small amount of information to the network every time an RRC connection is established causes a waste of radio resources.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently managing terminal capabilities in a network of a wireless communication system.

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

It is still another object of the present invention to provide a method for transmitting the latest terminal capability to a network only when the terminal capability is changed.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise forms disclosed. It will be possible.

According to an aspect of the present invention, there is provided a method for managing a terminal capability of 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 selectively transmitting the terminal capability to a base station according to whether the predetermined condition is satisfied or requesting the base station to acquire the terminal capability A terminal capability management method is provided.

According to another aspect of the present invention, there is provided a method of acquiring a terminal capability in a wireless communication system, the method comprising: receiving a status indicator related to the terminal capability from the terminal; Receiving a terminal capability from the MME or performing a process for acquiring the terminal capability from the terminal in response to a request from the MME, Method is provided.

According to the embodiments of the present invention, the following effects are obtained.

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

Second, since the terminal transmits 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 network capability information between networks.

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

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

Hereinafter, the structure, 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 the 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 evolved 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 Long Term Evolution (LTE) system. For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of "3rd Generation Partnership Project (Technical Specification Group Radio Access Network)" respectively.

Referring to FIG. 2, an E-UMTS includes an Access Gateway (AG) located at the end of a User Equipment (UE), a base station and a network (E-UTRAN) and connected to an external network. Typically, a base station may simultaneously transmit multiple data streams for broadcast services, multicast services, and / or unicast services. The AG can be divided into a part for handling user traffic and a part for processing control traffic. A new interface between the AG for handling new user traffic and the AG for handling control traffic can communicate with each other. One eNB has one or more cells. An interface for transmitting user traffic or control traffic may be used between eNBs. The CN (Core Network) may be configured as a network node for user registration of the AG and the UE. An interface for distinguishing E-UTRAN and CN may be used. The AG manages the mobility of the terminal in the TA (Tracking Area) unit. The TA consists of a plurality of cells. When the UE moves from one TA to another TA, it informs AG that the TA where the TA is located has changed.

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

4 and 5 show a control plane and a U-plane (User-Plane) structure of a radio interface protocol between a UE and an E-UTRAN based on the 3GPP radio access network standard . The wireless interface protocol consists of a physical layer, a data link layer, and a network layer horizontally, and vertically includes a user plane for transmitting data information, (Control Plane) for signaling transmission. The protocol layers of FIGS. 4 and 5 are based on the lower three layers of the Open System Interconnection (OSI) reference model widely known in communication systems, L1 (first layer), L2 (second layer), L3 (Third layer).

The control plane is a path through which control messages used by the UE and the network to manage calls are transmitted. The user plane means a path through which data generated in the application layer, for example, voice data or Internet packet data, is transmitted. Hereinafter, the layers of the control plane and the user plane of the wireless protocol will be described.

The physical layer as the first layer provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to a medium access control layer (upper layer) through a transport channel. Data moves between the MAC layer and the physical layer over the transport channel. Data is transferred between the transmitting side and the receiving side physical layer through the physical channel. The physical channel is modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses 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 an upper layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The function of the RLC layer may be implemented as a function block inside the MAC. In this case, the RLC layer may not exist. The Packet Data Convergence Protocol (PDCP) layer of the second layer performs a header compression function to reduce unnecessary control information for efficient transmission in an air interface having a narrow bandwidth when transmitting IP packets such as IPv4 or IPv6 .

The Radio Resource Control (RRC) layer located at the bottom of the third layer is defined only on the control plane and is configured by the configuration, re-configuration and release of radio bearers (RBs) And controls the logical channels, the transport channels, and the physical channels. RB denotes 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 UE and the network. If there is an RRC connection (RRC Connected) between the RRC layer of the UE and the RRC layer of the wireless network, the UE is in the RRC Connected Mode, otherwise it is in the RRC Idle Mode.

The Non-Access Stratum (NAS) layer at the top of the RRC layer performs functions such as session management and mobility management. The NAS layer exists in the Mobility Management Entity (MME) of the UE and the network.

The MME is a key control-node in an LTE access network. The MME is responsible for the tracking and paging procedures for the terminals in the idle state. In addition, the MME participates in the radio bearer activation / deactivation process and is responsible for selecting a Serving Gateway (SGW) at the time of 'Initial Attach' or during an intra-LTE handover including a core network relocation. It is. The MME takes charge of terminal authentication through interaction with a Home Subscriber Server (HSS). The NAS signaling is terminated at the MME, and the MME is responsible for creating and assigning a temporary identifier to the terminal. The MME verifies that the terminal has the authority to camp-on the service provider's PLMN (Public Land Mobile Network). MME is the endpoint for encryption / integrity protection for NAS signaling in the network and is responsible for security key management. MME provides a control flattening function for mobility between LTE and 2G / 3G access networks.

One cell constituting the eNB is set to one of the bandwidths of 1.25, 2.5, 5, 10, 20Mhz and the like to provide a downlink or uplink transmission service to a plurality of UEs. Different cells may be set up to provide different bandwidths.

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

A logical channel mapped to a transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH) Traffic Channel).

Embodiment: Delivery / Recycling of Terminal Capability Information

Since the size of the terminal capability information is not so large, providing the information to the network every time the terminal is changed from ECM-IDLE to ECM-CONNECTED results in a large overhead of the wireless section. Therefore, the present invention proposes a mechanism for storing the capability information of the terminal in a network and reusing it when necessary. For example, when the UE changes from ECM-IDLE to ECM-CONNECTED, the capability information of the UE can be reused. The capability information of the UE may be stored in a Mobility Management Entity (MME) in the network. Therefore, when the terminal is changed from ECM-IDLE to ECM-CONNECTED, if the MME has terminal capability information, the MME can provide the terminal capability information to the base station instead of the terminal.

In order to reuse the terminal capability stored in the network, there is a need for a mechanism for determining whether the stored terminal capability is up-to-date information in consideration of the characteristic that the terminal capability can be changed. As an example of the mechanism, a status indicator related to the terminal capability can be used. The status indicator is set for each terminal capability by the terminal. That is, the same status indicator means that the terminal capability information is the same. Therefore, if the status indicator of the terminal equals the status indicator of the network, 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 implementation, the status indicator may be a value tag. That is, a method of changing the value of the value tag every time the capability of the terminal is changed can be used. For example, a terminal transmits a value tag to a network whenever a terminal performs a procedure requiring a terminal capability. One example of a procedure in which the terminal capability is required is a 'Service Request' procedure. In the procedure in which the terminal capability is required, the network compares the value tag (first value tag) received from the terminal with the 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 UE can be stored in the MME, but it is possible to compare the status indicators and determine whether the UE capability information stored in the network is recycled or not, . The base station requiring the terminal capability may be the serving base station. An example of a procedure for performing the above procedure is as follows.

- base station:

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

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

     3. Receives 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 MME discards the terminal capability information received from the MME and requests capability information from the terminal.

- MME:

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

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

    2-2. If the first state indicator and the second state indicator are different, the base station requests the terminal capability information.

As described above, it is possible to determine whether the terminal capability information stored in the MME is up-to-date information, and determine whether to recycle the information, either in the base station or in the MME. However, it is preferable in the following respects to perform the above-described procedure in the MME.

First, if the base station determines that the terminal capability information stored in the MME is up-to-date information, the MME must transmit the terminal capability information to the base station in a state where the terminal capability information of the MME is unknown. Accordingly, if the base station determines that the information is not the latest information after receiving the terminal capability information from the MME, it results in waste of the S1 interface resources.

On the other hand, if the MME determines that the terminal capability information is the latest information, the MME provides the terminal capability information to the base station only when it determines that the stored terminal capability information is the latest information. Therefore, it is possible to eliminate the problem of wasting S1 interface resources to transmit unavailable terminal capability information.

Second, if the BS determines that the UE capability information stored in the MME is up-to-date, the BS must read the status indicator in the NAS container included in the RRC message received from the UE to compare the status indicator. Confirming the contents of the NAS container between the terminal and the MME is a network entity that is related to the AS layer, which is an ineffective operation by undermining the independence of the AS layer and the NAS layer.

On the other hand, if the MME determines that the capability information of the terminal is the latest information, the MME does not need to transmit the status indicator about the terminal capability information to the base station. Therefore, there is no inefficiency problem of the base station having to read the status indicator in the NAS container, and the independence of the AS layer and the NAS layer is ensured.

Hereinafter, a method for transferring / reusing terminal capability information according to an embodiment of the present invention will be described in more detail with reference to the MME. As a representative example, the case where 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 also be applied to other procedures by which an entity of a network such as a base station can receive (download) the capability of the terminal from the MME.

Transfer of terminal capability information in '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, even if the capability information of the terminal is stored in the MME during the 'Attach' procedure, the latest capability information can be received from the terminal while ignoring the capability information of the terminal. Accordingly, the MME can manage / maintain the latest information on the terminal. More specifically, in the process of performing the 'Attach' procedure, there may be the following cases.

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

Case 2: When the UE transmits a status indicator, capability information for the corresponding UE may already be stored in the MME. It is assumed that the MME does not have the latest capability information of the UE considering that the UE performs the 'Attach' procedure even if the stored status indicator matches the received status indicator. Accordingly, the MME replaces the stored status indicator with the status indicator received from the terminal. Thereafter, the MME requests the base station for capability information of the terminal and stores capability information received from the terminal through the base station.

Case 3: When the UE transmits the status indicator, the UE information about the corresponding UE may not be stored in the MME. Since the MME has no capability information of the UE, the MME requests the UE capability information and stores the capability information received from the UE.

Hereinafter, with reference to FIG. 6 and FIG. 7, a method of transmitting 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, the 'Initial Attach' procedure may be performed as follows.

1. The terminal performs an RRC connection establishment procedure. The RRC connection establishment procedure can be performed through a random access procedure. For example, the UE transmits a RACH preamble, and the BS allocates uplink resources to the UE as a response to the preamble. Thereafter, the MS transmits an 'RRC CONNECTION REQUEST' message to the BS, and the BS transmits an 'RRC CONNECTION SETUP' message to the MS. If the RRC connection establishment is successful, the UE transmits 'RRC CONNECTION COMPLETE' message to the base station. The MS 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 sends a second S1 control message including the NAS 'Attach Accept' to the base station as a response to the NAS 'Attach Request'. 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 NAS 'Attach Accept' from the MME.

5. The base station can forward the message including the 'Attach Accept' received from the MME to the MS. The message is for transferring the NAS message from the MME to the terminal, and may be omitted if the NAS 'Attach Accept' is transmitted 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 BS transmits a 'SECURITY MODE COMMAND' message to the MS. After activating 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 information on the terminal capability from the MME, the base station receives capability information from the terminal through the RRC procedure (UE Capability transfer RRC procedure) for transmitting the terminal capability. Specifically, the BS transmits 'UE CAPABILITY ENQUIRY' message requesting the latest capability of the UE to the UE. The terminal transmits 'CAPABILITY INFORMATION' message including the latest terminal capability information to the base station as a response to the message. The 'CAPABILITY INFORMATION' message may include a value tag related to the terminal capability.

7. The base station performs the RRC connection reconfiguration procedure using the received terminal capability information. Specifically, the base station sets up a radio bearer and transmits an 'RRC CONNECTION RECONFIGURATION' message to the UE instructing RRC connection reconfiguration. If the RRC message is transmitted to the NAS 'Accept Attach' terminal through the 'DL INFORMATION TRANSFER' message in step 5, the NAS 'Accept Attach' does not include the RRC message. 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 'RRC CONNECTION RECONGIGURATION'. After completing the reconfiguration of the RRC connection, the UE transmits an 'RRC RECONFIGURATION COMPLETE' message to the base station. The RRC message may include an 'Attach Complete' message to inform 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 the NAS 'Attach Complete message transmitted from the UE.

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

10. The MME regards 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 and stores the value tag.

In step 3, the capability and corresponding value tag for the corresponding terminal may already be stored in the MME. The MME considers that the terminal capability information in the MME is not the latest information, considering that the terminal is performing 'Initial Attach' even if the existing value tag is stored. Accordingly, the MME acquires the latest capability information of the terminal and the value tag corresponding to the capability information through steps 5 to 10 above.

In addition, the procedures 5 and 6 may be changed in accordance with whether the RRC message related to the 'UE Capability transfer' procedure is encrypted or not.

FIG. 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 process illustrated in FIG. 6 except that the terminal separately transmits the value tag regarding the terminal capability information at the beginning of the procedure. Referring to FIG. 7, in order for the terminal to initially transmit the value tag to the MME, it can be seen that steps 1 to 3 of FIG. 6 are modified as follows. Step 10 is omitted.

1. The terminal performs an RRC connection establishment procedure. If the RRC connection establishment is successful, the UE transmits 'RRC CONNECTION COMPLETE' message to the base station. The terminal includes the NAS 'Attach Request' and the NAS value tag regarding 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. As a response to the NAS 'Attach Request', the MME transmits a first S1 control message including the NAS 'Attach Accept' to the base station via the S1 interface. Also, the MME stores the value tag and regards it as a value tag related to the latest terminal capability acquired through steps 4 to 9.

In step 3, the capability information for the corresponding terminal may or may not be stored in the MME. Considering that the MME is performing the 'Initial Attach' procedure, the MME requests the latest terminal capability information to the base station regardless of whether the terminal capability exists or not.

In Figures 6 and 7, the terminal capability and the value tag are shown to be stored together. This is only to show the relevance of the terminal capability and the value tag, which does not mean that the terminal capability and the value tag are stored at the same time. Terminal capabilities and value tags can be stored at the same time or at different times, depending on the implementation.

Delivery / reuse of terminal capability information in 'Service Request'

When the terminal performs a 'Service Request' procedure for the purpose of transmitting a response to a paging of a network or data generated by a user to a network, it is common that the capability information of the terminal exists in the MME. If the MME has up-to-date information on the terminal capability when the base station needs to know the capability of the terminal, the base station can download and use the capability 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. For example, when the MME receives the value tag (first value tag) from the terminal, it determines whether or not the stored value tag (second value tag) exists. If the second value tag exists, it is determined whether the first value tag is identical to the second value tag. If any of the above conditions is 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 on 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 the latest terminal capability to the MME. Specifically, the base station receiving the request from the MME sends an instruction to the terminal to transmit capability information. Upon receiving the command from the base station, the terminal transmits its capability information to the base station. The BS transmits capability information received from the MS to the MME. The MME regards the capability information as the latest information about the terminal and stores the information. Optionally, the capability information may include a value tag associated with 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 specifically described with reference to FIGS.

8 shows a process of performing a 'Service Request' procedure when the MME has latest capability information of the UE. In the above procedure, the capability information of the UE stored in the MME is transmitted to the base station for recycling. The detailed procedure is as follows.

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

2. After receiving the RRC message, the base station transmits 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 judges whether the terminal capability is recyclable when there is the 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 regards the stored terminal capability as 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, the capability information of the terminal downloaded from the MME can 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 transmits a third S1 control message to the MME via the S1 interface as a response to the second S1 control message. The third S1 control message may be 'Initial Context Setup Complete' or a corresponding control message.

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

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

2. After receiving the RRC message, the base station transmits 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 judges whether the terminal capability is recyclable when there is the 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. Therefore, the MME requests the latest terminal capability information corresponding to the first value tag to the base station.

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

i) A control command for requesting terminal capability information may be included in a second S1 control message transmitted to the base station via the S1 interface. The second S1 control message may be an 'Initial Context Setup Request' message or a corresponding control message. The control command for requesting the UE capability information may be a UE Capability Request. After receiving the control command, the base station receives the latest capability information from the terminal and then transmits the capability information to the MME (FIG. 9).

ii) may not include the UE capability and UE CAPABILITY REQUEST in the second S1 control message transmitted to the base station via the S1 interface. The second S1 control message may be an 'Initial Context Setup Request' message or a corresponding control message. That is, the request for the latest capability information of the terminal to the base station can be indicated by the absence of the terminal capability and the 'UE Capability Request' in the S1 control message. After receiving the second S1 control message, the base station receives the latest capability information from the terminal and then transmits 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 to the MME from the MME, the base station receives capability information from the terminal through the RRC procedure (UE Capability transfer RRC procedure) for transmitting 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 transmits the capability information of the UE received from the UE to the MME by including it in the third S1 control message. The third S1 control message may be 'Initial Context Setup Complete' or a corresponding control message as a response to the second S1 control message occasioned by the MME.

9. The MME stores capability information of the transmitted 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 regards it as a value tag corresponding to the latest capability information of the terminal.

With respect to the process 10, the capability information of the terminal received from the base station may include a value tag. In this case, the MME ignores the value tag received together with the message 'Service request', and regards the value tag included in the capability information of the terminal as a value tag corresponding to the latest capability information of the terminal and stores the value tag.

In addition, steps 6 and 7 may be changed in accordance with whether the RRC message related to the 'UE capability transfer' procedure is encrypted or not.

In Figures 8 to 10, the terminal capability and the value tag are shown to be stored together. This is only to show the relevance of the terminal capability and the value tag, which does not mean that the terminal capability and the value tag are stored at the same time. Terminal capabilities and value tags can be stored at the same time or at different times, depending on the implementation.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

In this document, the embodiments of the present invention have been mainly described with reference to the data transmission / reception relationship between the terminal and the base station. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or 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. The term 'terminal' may be replaced with terms such as User Equipment (UE), Mobile Station (MS), and Mobile Subscriber Station (MSS).

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of 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) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like which performs the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-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 description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

The present invention can be applied to a method for managing terminal capability in a wireless communication system. More particularly, the present invention can be applied to a method of managing a capability of a terminal by a Mobility Management Entity (MME) of a network in a wireless communication system.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

1 shows a method of transmitting a terminal capability in a network connection.

2 shows the network structure of the E-UMTS.

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

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

FIG. 6 illustrates a method of transmitting a terminal capability when 'Initial Attach' is performed according to an embodiment of the present invention.

FIG. 7 illustrates a method of transmitting a terminal capability in 'Initial Attach' according to another embodiment of the present invention.

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

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

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

Claims (15)

A method for managing a terminal capability of a Mobility Management Entity (MME) of a network in a wireless communication system, Receiving a status indicator for the terminal capability from a base station, the status indicator comprising a first value tag associated with the terminal capability; Comparing the first value tag in the status indicator with a second value tag stored in the MME; Determining terminal capability information stored in the MME as the latest terminal capability information when the first value tag and the second value tag are the same and transmitting the terminal capability information stored in the MME to the base station; And Determining that the terminal capability information stored in the MME is not the latest terminal capability information when the first value tag and the second value tag are not the same and transmitting a request message for obtaining the terminal capability information of the terminal to the base station ≪ / RTI > The method according to claim 1, Wherein the status indicator is received via an S1 control message. 3. The method of claim 2, Wherein the S1 control message is an " Initial UE Message ". 3. The method of claim 2, Determining whether a 'Service Request' message is included in the S1 control message; ≪ / RTI > delete delete delete The method according to claim 1, Wherein the terminal capability information and the request message are transmitted via an S1 control message. 9. The method of claim 8, Wherein the S1 control message is an " Initial Context Setup Request ". 9. The method of claim 8, Wherein the S1 control message is a UE Capability Request. delete The method according to claim 1, Receiving the requested terminal capability information from the base station through the request message; And And storing the received terminal capability information in the MME as the latest terminal capability information. delete delete delete

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