KR102270370B1 - Method and apparatus for location registration of terminal in mobile communication system - Google Patents

Abstract

A method and apparatus for registering a location of a terminal in a mobile communication network are disclosed. When the terminal receives a rejection message for the location registration request from the network after transmitting the location registration request message to the network, the terminal waits until the wireless connection disconnection with the network is completed. Send a registration request message.

Description

{Method and apparatus for location registration of terminal in mobile communication system}

The present invention relates to a method and apparatus for registering a location of a terminal in a mobile communication network. More specifically, the present invention relates to a method and apparatus for efficiently using radio resources in terms of time reduction or resource saving compared to existing methods and apparatuses in the process of handover, location registration, and wireless connection re-establishment of a terminal. will be.

Early wireless communication systems were developed to provide voice services while ensuring user activity. Moreover, the wireless communication system is gradually expanding its scope not only to voice but also to data services, and has now developed to the extent that it can provide high-speed data services.

1 is a diagram illustrating a general wireless communication system. Referring to FIG. 1 , a wireless communication system may include a terminal 100 , a radio access network 120 (Radio Access Network, RAN), and a core network 140 .

The radio access network 120 may include radio access points 110 and 115, radio access points. The radio access points 110 and 115 may interact with the terminal 100 through a wireless interface. Other elements of the wireless communication system are mainly connected by wire. As possible examples of the radio access points 110 and 115 , an evolved Node B (eNB), a Node B, NB, or a radio network subsystem including the same (Radio Network Subsystem, RNS), a base station ( There is a base transceiver station (BTS) or a base station subsystem (BSS) including the same, a wireless access point, and the like. Except for some exceptions, the radio access points 110 and 115 generally consist of one or more cells, and the cell governs a specific range, and the terminal 100 connects from the radio access points 110 and 115 within the range of the cell. get service Here, the cell means a cell of a general cellular system, and the radio access points 110 and 115 are devices that manage and control each cell, but in the present specification, for convenience, the cell and the radio access point 110 and 115 are the same. can be used for meaning.

Meanwhile, the core network 140 may include a RAN control element 130 (RAN control entity). The RAN control element 130 is responsible for overall control functions such as mobility management, authentication and security. As an example of the RAN control element, a Mobility Management Entity (MME) and a Serving General Packet Radio Service (GPRS) support element (Serving GPRS Support Node, SGSN) may be included.

In order to provide a service to the terminal 100 , the wireless communication system including the radio access point 110 must maintain a connection with the terminal 100 or retain terminal 100-related information (context). In addition, the wireless communication system performs a handover process, a location registration process, or a wireless connection re-establishment process in order to maintain a connection with the terminal 100 or put a context related to the terminal 100 in the right place.

The handover procedure is mainly used to change the interacting radio access point 110 as the connected terminal 100 moves or according to other reasons. An example of the other reason is load balancing.

The location registration process includes an attach process and a tracking area (TA) update (TA Update, TAU) process. The attach process may be used when the terminal 100 first accesses the network or when a detached terminal 100 accesses the network. The TAU process may be performed in more various situations, and as a representative example of use, the TAU process may be performed when the terminal 100 enters a new TA.

In addition to the handover process and location registration process mainly caused by the mobility of the terminal, the wireless connection between the terminal 100 and the radio access point 110 is unstable and may not be suitable for use for a certain period of time. In this case, the radio connection re-establishment process may be performed between the terminal 100 and the radio access point 110 before starting the handover process and the location registration process separately or without performing the handover process and the location registration process.

An object of the present invention is to provide a method and apparatus for efficiently using radio resources in terms of time reduction or resource saving by improving a handover process, a location registration process, and a radio connection re-establishment process of a terminal.

An embodiment of the present invention for achieving the above technical problem is a method of registering a location of a terminal in a mobile communication system, the method comprising: transmitting a location registration request message to a network; waiting until the wireless connection with the network is disconnected when receiving a rejection message for the location registration request from the network; and when the disconnection of the wireless connection is completed, transmitting a new location registration request message to the network.

An embodiment of the present invention for achieving the above technical problem is a method of registering a location of a terminal in a mobile communication system, the method comprising: transmitting a location registration request message to a network; and, upon receiving a rejection message for the location registration request from the network, immediately transmitting a new location registration request message to the network.

An embodiment of the present invention for achieving the above technical problem is a method for controlling location registration of a base station in a mobile communication system, the method comprising: receiving a connection release command message corresponding to a location request of a terminal from a core network; and when the connection release command message is received, immediately transmitting a connection release message to the terminal.

An embodiment of the present invention for achieving the above technical problem is a method for controlling location registration of a base station in a mobile communication system, the method comprising: receiving a connection release command message corresponding to a location request of a terminal from a core network; and waiting until a new location registration request message for the network is received from the terminal.

An embodiment of the present invention for achieving the above technical problem is a terminal for performing location registration in a mobile communication system, comprising: a transceiver for transmitting and receiving signals and data with a network; and transmitting a location registration request message to the network, and when receiving a rejection message for the location registration request from the network, waits until the wireless connection disconnection with the network is completed, and when the wireless connection disconnection is completed, and a control unit controlling to transmit a new location registration request message to the network.

An embodiment of the present invention for achieving the above technical problem is a terminal for performing location registration in a mobile communication system, comprising: a transceiver for transmitting and receiving signals and data with a network; and a control unit that transmits a location registration request message to the network, and controls to transmit a new location registration request message to the network immediately upon receiving a rejection message for the location registration request from the network.

An embodiment of the present invention for achieving the above technical problem is a base station for controlling location registration of a terminal in a mobile communication system, comprising: a transceiver for transmitting and receiving signals and data to and from the terminal and the core network; and a control unit that controls to transmit a connection release message to the terminal immediately upon receiving a connection release command message corresponding to a location request of the terminal from the core network.

An embodiment of the present invention for achieving the above technical problem is a base station for controlling location registration of a terminal in a mobile communication system, comprising: a transceiver for transmitting and receiving signals and data to and from the terminal and the core network; and a control unit configured to receive a connection release command message corresponding to a location request from the terminal from the core network and to wait until a new location registration request message for the network is received from the terminal.

According to the method and apparatus for registering a location of a terminal in a mobile communication network according to the present invention, it is possible to efficiently use radio resources in terms of time reduction or resource saving.

1 is a diagram illustrating a typical wireless communication system;
2 is a diagram illustrating an example of a situation in which the first problem may occur;
3 is a view showing the operation of a terminal and a network to which the first and second embodiments of the present invention can be applied;
4 is a diagram specifically illustrating the operation of a RAN control element and a radio access point according to a second embodiment of the present invention;
5 is a flowchart illustrating a process of transmitting a location registration message of a terminal 100 that reuses radio resources by a radio access point in a second embodiment of the present invention;
6 is a diagram illustrating a process for recognizing that a terminal to which a radio access point is handed over is a secondary service terminal according to an embodiment of the present invention related to handover of a terminal;
7 is a flowchart illustrating a process of reestablishing a wireless connection by reusing a wireless connection with a radio access point with which the terminal has secondary interaction according to an embodiment of the present invention related to the wireless connection re-establishment of the terminal;
8 is a block diagram illustrating the configuration of a terminal according to an embodiment of the present invention, and
9 is a block diagram illustrating the configuration of a base station according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this case, it should be noted that the same components in the accompanying drawings are indicated by the same reference numerals as possible. Also, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted.

In addition, in describing the embodiments of the present invention in detail, the radio access network specified by the 3GPP standard, Long Term Evolution (LTE) and Evolved Packet Core (EPC), which are core networks, will be the main targets. , the main gist of the present invention is applicable to other communication systems having a similar technical background with slight modifications within a range that does not significantly depart from the scope of the present invention, which can be achieved by those of skill in the technical field of the present invention. judgment will be possible.

In the past, the terminal 100 mainly interacted with one radio access point 110 , but recently it has become able to interact with one or more radio access points 110 and 115 as well. For example, as described above, two radio access points 110 and 115 connected to the terminal 100 are illustrated in FIG. 1 . However, the present invention is not limited to the embodiment shown in FIG. 1 , and the radio access network 120 is not necessarily composed of two radio access points 110 and 115 , and the terminal 100 always has two radios. It is obvious that it does not interact with the access points 110 and 115 .

Hereinafter, throughout this specification, unless otherwise specified, when only one radio access point 110 is referred to, the radio access point 110 means a general radio access point, and the two radio access points 110 and 115 are referred to together. In this case, the first radio access point 110 interacts primarily with the terminal 100, and the second radio access point 115 interacts with the terminal 100 secondaryly. It means the radio access point 115 that works. Also, when the number of radio access points 110 and 115 connected to the terminal 100 is three or more, there may be one or more radio access points 115 secondary to interact with the terminal 100 .

In the network structure described above, the following problems may occur. One is that it may take a long time when the terminal 100, which has failed to register the location for a specific reason, re-registers the location with the corresponding radio access point 110, and the other is that it interacts with two or more radio access points 110 and 115. When the connection state with the radio access point 110 with which the terminal primarily interacts deteriorates, resource waste may occur because the connection state with the radio access point 115 with the secondary interaction is not considered at all. that there is Hereinafter, the problem situation will be described in more detail.

2 is a diagram illustrating an example of a situation in which the first problem may occur. First, in FIG. 2 , the terminal 100 is location registered or serviced in a wireless communication system using another radio access technology (RAT), or in another RAN control element group having a different RAN control element group identifier. there may have been Alternatively, the terminal may be in an idle state.

When the terminal 100 is moved from another RAT or another RAN control element group as in 210, the terminal transmits a TAU request message to the RAN control element 130 as in 220. Alternatively, when the terminal has data to be transmitted to or received from the network in the idle state as in 215 , the terminal transmits a service request message to the RAN control element 130 at 220 . In this case, the message sent by the terminal 100 to the RAN control element 130 is not directly transmitted from the terminal 100 to the RAN control element 130 , but is transmitted through the radio access point 110 .

When a problem occurs, the RAN control element 130 receiving the TAU request message or the service request message from the terminal 100 rejects the request message of the terminal 100 as shown in 240, for example, a TAU reject message or a service reject message. may be sent to the terminal 100 . In this case, the RAN control element 130 may send information explaining or implying the cause of the problem into the rejection message. In addition, the rejection message is not directly transmitted from the RAN control element 130 to the terminal 100 , but is transmitted to the terminal 100 through the radio access point 110 .

In step 240 , the terminal 100 receiving the rejection message from the RAN control element 130 may send a new Attach request message to the RAN control element 130 through the radio access point 110 for a specific cause included in the rejection message. (280). Here, as an example of a specific cause, when the RAN control element 130 does not obtain the identifier of the terminal 100, when the terminal 100 is implicitly detached, bearer information is not activated at all. If not, etc. These three causes are matched to Cause values 9, 10, and 40, respectively, in the Evolved Packet System (EPS).

On the other hand, the RAN control element 130 that has sent the rejection message to the terminal 100 in 240 may give a command to release the terminal 100 related context to the radio access point 110 in 250 . This command may be delivered through a UE CONTEXT RELEASE COMMAND message.

In addition, the radio access point 110 receiving the release command from the RAN control element 130 may send a message to release the connection to the terminal 100 as shown in 260 . An example of the release message transmitted from the radio access point 110 to the terminal 100 is an RRCConnectionRelease message.

At this time, at 260, the release message delivered from the radio access point 110 to the terminal 100 arrives and the time when the radio connection release with the network is completed is at 280, when the terminal 100 sends a new Attach request to the RAN control element 130. If it is earlier than the time of sending the message, the terminal 100 may perform the attach process without any problem.

However, at 260, the release message transmitted from the radio access point 110 to the terminal 100 arrives and the time when the release of the radio connection with the network is completed is at 280, when the terminal 100 sends a new Attach request to the RAN control element 130. Problems can arise when it is later than when the message is sent. In other words, this situation means that the terminal 100 sends an Attach request message to the RAN control element 130 and then the radio connection is released. Accordingly, the terminal 100 recognizes that a problem has occurred in the attach process, waits for a relatively long period of time (for example, for 10 seconds), and then attempts location registration again. While waiting for such a long period of time, the terminal 100 cannot receive a service, and the user of the terminal 100 has to suffer inconvenience.

Hereinafter, an embodiment of the present invention for solving the problem as shown in FIG. 2 will be described in detail. However, the problem to be solved in the present invention is not limited to the situation shown in FIG. 2, but it is self-evident that it is for all situations in which it may take a long time when a terminal that has failed to register a location for a specific reason re-registers a location with a corresponding radio access point. Do.

In order to solve the problem described above, two embodiments of the present invention are possible. However, it is obvious that all possible modifications that can achieve the technical spirit of the present invention can be made in addition to the embodiments described below.

The first embodiment according to the present invention is described based on FIG. 2, the arrival time of the release message delivered from the radio access point 110 to the terminal 100 at 260 is the terminal 100 at 280 the RAN control element ( 130) to make it earlier than the time when a new Attach request message is sent.

Also, in the second embodiment according to the present invention, the connection between the terminal 100 and the radio access point 110 is not released, that is, in the case of FIG. 2 , 260 is not performed. Therefore, according to the second embodiment of the present invention, the release message from the radio access point 110 is not transmitted to the terminal 100 .

The fundamental difference between the above first and second embodiments is whether or not the wireless connection is reused. That is, in the first embodiment, the connection between the terminal 100 and the radio access point 110 is always released and the terminal 100 requests a new location registration. On the other hand, in the second embodiment, the terminal 100 reuses the existing wireless connection to request a new location registration without disconnecting the connection between the terminal 100 and the radio access point 110 .

In both the first embodiment and the second embodiment, when the release message delivered to the terminal 100 from the radio access point 110, which was a problem in FIG. 2, arrives at the terminal and the radio connection is released 260, the terminal 100 By preventing a situation later than the timing 280 of transmitting a new location registration request to the RAN control element 130, the time reduction effect in that the terminal waits for a long period of time and then makes a location registration request again there is

3 is a diagram illustrating a terminal 100 and a network operation to which the first and second embodiments of the present invention can be applied. Specifically, the terminal 100 from the RAN control element 130 to the radio access point 110. It shows an operation of transmitting at least one of an indicator and a timer indicating that a new location registration is required or the RAN control element 130 or the radio access point 110 transmits the timer to the terminal 100 .

Referring to FIG. 3 , the terminal 100 and the radio access point 110 may recognize a situation in which a new location registration process is required. In addition, the terminal 100 or the radio access point 110 may transmit a message to be transmitted in a new location registration process or wireless connection release process based on a timer at an appropriate time.

In step 310, the RAN control element 130 may determine that a new location registration of the terminal 100 is necessary in a specific problem situation. Here, the specific problem situation may be a situation corresponding to at least one of Cause values 9, 10, and 40 in the case of EPS as described above. In addition, the determination made by the RAN control element 130 in step 310 may be a determination according to location registration of the terminal 100 or a service request.

In step 320 , the RAN control element 130 may transmit at least one of a timer and an indicator indicating that a new location registration of the terminal 100 is required to the radio access point 110 . At this time, information transmitted from the RAN control element 130 to the radio access point 110 may be transmitted through a DOWNLINK NAS TRANSPORT message. The DOWNLINK NAS TRANSPORT message is used to transfer a NAS (Non Access Stratum, NAS) message between the terminal 100 and the RAN control element 130 . Examples of the NAS message delivered as the DOWNLINK NAS TRANSPORT message include TAU reject, Service reject, and the like. Meanwhile, information transmitted from the RAN control element 130 to the radio access point 110 may be transmitted through a UE CONTEXT RELEASE COMMAND message instructing disconnection from the terminal 100 .

In addition, an indicator indicating that a new location registration of the terminal 100 is required may be expressed in various ways. For example, the indicator may be expressed as simple binary information, or it may be expressed as a reason or a Cause value in which a new location registration of the terminal 100 is required.

In step 330 , the radio access point 110 may transmit a timer to the terminal 100 . To the terminal 100 , the timer may be included in a DLInformationTransfer message or a NAS message included in the DLInformationTransfer message.

On the other hand, the timer transmitted from the RAN control element 130 to the radio access point 110 in step 320 and the timer transmitted from the radio access point 110 to the terminal 100 in step 330 may be set to the same value or different from each other. It can also be set to a value.

Hereinafter, in a situation such as that shown in FIG. 3 , according to the first embodiment of the present invention, at least one of an indicator and a timer that the radio access point 110 needs to register a new location of the terminal 100 from the RAN control element 130 . The operation of the RAN control element 130 and the radio access point 110 in the case of receiving and not receiving both will be described in detail.

When the radio access point 110 does not receive both the indicator and the timer from the RAN control element 130, it is necessary to release the radio connection as quickly as possible before the terminal 100 requests a new location registration in the network. .

Accordingly, when the RAN control element 115 recognizes a situation in which a new location registration of the terminal 100 is required, the RAN control element 115 may send a UE CONTEXT RELEASE COMMAND message to the radio access point 110 as quickly as possible. For example, a UE CONTEXT RELEASE COMMAND message may be sent to the radio access point 110 as soon as a NAS message notifying the location registration rejection is sent to the terminal 100 . In addition, the radio access point 110 may disconnect the radio connection of the terminal 100 immediately upon receiving the UE CONTEXT RELEASE COMMAND message from the RAN control element 130 . For example, the radio access point 110 may send an RRCConnectionRelease message that is a connection release message to the terminal 100 immediately upon receiving the UE CONTEXT RELEASE COMMAND message from the RAN control element 130 . Also, the terminal 100 may perform a wireless connection release immediately upon receiving a connection release message from the radio access point 110 .

When the radio access point 110 receives the indicator from the RAN control element 130 but not the timer, the radio access point 110 recognizes a situation in which the terminal 100 requests a new location registration through the indicator. Therefore, the radio access point 110 may cause the RAN control element 130 to disconnect the radio connection of the terminal 100 immediately upon recognizing a situation in which new location registration is required through the indicator regardless of whether the RAN control element 130 sends the UE CONTEXT RELEASE COMMAND message. .

For example, if the indicator is received through the UE CONTEXT RELEASE COMMAND message, the radio access point 110 immediately transmits an RRCConnectionRelease message to the terminal 100, and if the indicator is received through another type of message, the UE CONTEXT RELEASE COMMAND message is received. It is possible to immediately transmit the RRCConnectionRelease message to the terminal 100 even before.

When the radio access point 110 receives the timer from the RAN control element 130 , the radio access point 110 may disconnect the radio connection of the terminal 100 from an appropriate time within the time indicated or symbolized by the timer. Here, the timer can be viewed as a kind of promise. For example, the terminal 100 can be viewed as a promise not to make a new location registration request to the RAN control element 130 within the time indicated or symbolized by the timer received by the radio access point 110 at least. Also, an example of an appropriate time when the timer is started may be a time when the radio access point 110 receives the timer.

Next, a configuration for allowing the terminal 100 to request a new location registration by reusing a wireless connection according to the second embodiment of the present invention in a situation such as that shown in FIG. 3 will be described in detail.

When the radio access point 110 does not receive both an indicator and a timer indicating that a new location registration of the terminal 100 is required in step 320 of FIG. 3 , the radio access point 110 reuses a radio connection in which the terminal 100 already exists. Therefore, it is necessary to maintain a wireless connection for a certain period of time with room to request a new location registration. Here, the predetermined period may be determined by a timer unique to the radio access point 110 .

Therefore, if the RAN control element 115 recognizes a situation requiring new location registration of the terminal 100 in step 310 , it may not send the UE CONTEXT RELEASE COMMAND message to the radio access point 110 in step 320 . Also, the radio access point 110 may wait without releasing the radio connection of the terminal 100 for a certain period even when receiving the UE CONTEXT RELEASE COMMAND message from the RAN control element 130 .

When the terminal 100 requests a new location registration to the RAN control element 130 while the radio access point 110 is waiting, the radio access point 110 receives a UE CONTEXT RELEASE COMMAND message from the RAN control element 130. In spite of this, the wireless connection of the terminal 100 may not be released.

When the radio access point 110 receives the indicator from the RAN control element 130 but not the timer, the radio access point 110 recognizes that the terminal 100 requests a new location registration. Therefore, the radio access point 110 recognizes a situation in which a new location registration of the terminal 100 is required through the indicator regardless of whether the RAN control element 130 sends the UE CONTEXT RELEASE COMMAND message, the radio connection of the terminal 100 It may wait until a new location registration request is received from the terminal 100 without release. In addition, the standby time of the radio access point 100 may be maintained for a timer period unique to the radio access point 110 .

When the radio access point 110 receives the timer from the RAN control element 130 , the radio access point 110 may not disconnect the radio connection of the terminal 100 from an appropriate time during the time indicated or symbolized by the timer. Here, the timer can be viewed as a kind of promise. For example, the terminal 100 may be viewed as a promise to request a new location registration within a time indicated or symbolized by a timer received by the radio access point 110 . Also, an example of an appropriate time when the timer is started may be a time when the radio access point 110 receives the timer.

Next, the operation of the terminal 100 according to the first and second embodiments of the present invention in the situation shown in FIG. 3 will be described in detail.

According to the first embodiment of the present invention, when the terminal 100 does not receive a timer from the network in step 330 of FIG. 3 , the terminal 100 waits until the radio connection is disconnected by the radio access point 110 and then receives a new You can try to request a location registration.

Alternatively, the terminal 100 may attempt a new location registration request using a method applied to the above method. That is, the terminal 100 waits for the wireless connection to be disconnected for a certain period of time, then releases the wireless connection with the radio access point 110 after a certain time elapses, establishes a new connection with the radio access point 110 and requests a location registration. you can try

In addition, when the terminal 100 receives the timer in step 330 , it may attempt a new location registration request after waiting at least for the time indicated or symbolized by the timer. In this case, if the wireless connection is first released while waiting for the timer to expire, the terminal 100 may immediately stop the timer and attempt a new location registration request.

In addition, since the terminal 100 can recognize that a new location registration is required from a message received from the network, for example, a location registration rejection message in step 330 of FIG. It can be recognized that it is effective. Accordingly, when the terminal 100 receives a message to release the wireless connection from the radio access point 110 , it can immediately leave the connected state without delay. The information received so that the terminal 100 can recognize that a new location registration process is required may be information received from the NAS layer. In addition, the NAS layer may deliver the information to the RRC layer so that the terminal 100 can immediately leave the connected state without delay.

In a specific situation, some current terminals 100 are designed to delay the wireless connection release process for a period of 60 ms when receiving a wireless connection release message from the radio access point 110 . Therefore, in the embodiment of the present invention, the terminal 100 leaving the connected state 'without delay' may mean 'within 60 ms after receiving the message' or 'without waiting time of 60 ms'.

Next, according to the second embodiment of the present invention, when the terminal 100 does not receive the timer in step 330 of FIG. 3 , the terminal may transmit a new location registration request to the RAN control element 130 immediately after step 330. have. In addition, when the terminal 100 receives the timer in step 330, the terminal may transmit a new location registration request to the RAN control element 130 within a time corresponding to the value indicated or symbolized by the timer.

Meanwhile, the third embodiment in which the terminal 100 determines whether to reuse a wireless connection for new location registration according to a situation is also possible.

Specifically, according to the third embodiment of the present invention, in step 310 of FIG. 3 , the RAN control element 130 may start a timer when it is determined that a new location registration of the terminal 100 is required. Here, the timer may be the same as or different from the timer transmitted by the RAN control element 130 to the radio access point 110 . In addition, the timer of the RAN control element 130 may be started after or simultaneously with transmitting at least one of an indicator and a timer through a location registration related message to the radio access point 110 in step 320 .

Thereafter, if the terminal 100 transmits a new location registration request to the RAN control element 130 before the timer expires, the RAN control element 130 transmits a UE CONTEXT RELEASE COMMAND message to the radio access point 110. Location registration of the terminal 100 may be performed without release. That is, location registration is performed by reusing the wireless connection. In this way, when the terminal 100 attempts to register a location before the timer expires, the RAN control element 130 may stop or terminate the timer upon receiving the location registration request message.

On the other hand, if the terminal 100 does not transmit a new location registration request until the timer expires, the RAN control element 130 triggers radio connection release. The wireless connection release triggering may be performed by sending a UE CONTEXT RELEASE COMMAND message to the radio access point 110 .

4 is a diagram specifically illustrating the operation of the RAN control element 130 and the radio access point 110 according to the second embodiment of the present invention.

As described above, according to the second embodiment of the present invention, even if the RAN control element 130 sends a UE CONTEXT RELEASE COMMAND message to the radio access point 110 to instruct the context release, the radio access point 110 is the terminal 100 ) may not release the relevant context or release the wireless connection. Accordingly, the radio access point 110 may notify the RAN control element 130 that the terminal 100 related context is not released or that the radio connection is not released. When the terminal 100 re-uses an existing radio connection and performs a new location registration request, the radio access point 110 maintains a radio connection for a certain period of time even if it receives a request for context release or radio connection release from the RAN control element 130 . It has been explained before that there are cases when it is necessary to maintain.

Referring to FIG. 4 , in step 410 , the RAN control element 130 may send a message instructing the context release of the terminal 100 to the radio access point 110 . An example of the message transmitted in step 410 includes a UE CONTEXT RELEASE COMMAND message. The radio access point 110 receiving the message from the RAN control element 130 may not perform context release or radio connection release despite the command of the RAN control element 130 .

In addition, in step 420, the radio access point 110 may notify the terminal 100 related context through a message transmitted to the RAN control element 130 that the radio connection is not released. An example of the message transmitted in step 420 may be at least one of a UE CONTEXT RELEASE COMPLETE and an ERROR INDICATION message. In this case, the message transmitted by the radio access point 110 to the RAN control element 130 may contain an Information Element (IE) indicating that the terminal 100 related context is not released or the radio connection is not released. Examples of IEs that may be included in the message include Cause and indicator having a specific value.

Also, the message that the radio access point 110 transmits to the RAN control element 130 may be a new type of message. When the IE indicating that the terminal 100-related release has not been performed is transmitted through a new message, as an embodiment, the new message name may be UE CONTEXT RELEASE FAILURE.

Conventionally, when the RAN control element 130 commands context release, the radio access point 110 has no choice but to operate according to the command of the RAN control element 130 . However, according to the second embodiment of the present invention described above, the radio access point 110 may not release a context or a wireless connection in a specific situation.

On the other hand, when applying FIG. 4 to the third embodiment of the present invention, the RAN control element 130 in step 410 when it does not receive a new location registration request from the terminal 110 until its timer expires. The context release command is sent. Also, even if the timer of the RAN control element 130 expires and a context release command is transmitted to the radio access point 110, if the timer of the radio access point 110 itself expires before the timer expires, the radio access point 110 controls the RAN as in step 420. A message indicating that context release has not been performed may be transmitted to the element 130 .

5 is a flowchart illustrating a process in which the radio access point 110 transmits a location registration message of the terminal 100 that reuses radio resources in the second embodiment of the present invention.

By the process shown in FIG. 5 , the radio access point 110 can successfully transmit the message to the RAN control element 130 even when the terminal 100 reuses radio resources to transmit a location registration request message.

Referring to FIG. 5 , in step 510 , the terminal 100 transmits a message requesting location registration to the radio access point 110 . The message transmitted by the terminal 100 may ultimately be a NAS message transmitted to the RAN control element 130 , and may be transmitted through , for example, a ULInformationTrnasfer message. According to the second embodiment of the present invention, when the terminal 100 reuses a wireless connection to make a new location registration request, the terminal may transmit specific information in a location registration request message. Specific information included in the message may be used to notify that the terminal 100 re-uses a wireless connection and makes a new location registration request.

In step 520 , the radio access point 110 may transmit the location registration request message of the terminal 100 to the RAN control element 130 . In this case, at least one of INITIAL UE MESSAGE and UPLINK NAS TRANSPORT messages may be used to transmit the message of the terminal 100 .

The existing location registration request message is mainly delivered through INITIAL UE MESSAGE. In order for INITIAL UE MESSAGE to be suitable for delivering location registration messages, a special IE is defined unlike UPLINK NAS TRANSPORT messages and DOWNLINK NAS TRANSPORT messages that carry general NAS messages. Also, INITIAL UE MESSAGE is limited to deliver the first NAS message that is sent after a wireless connection is established.

However, if the wireless connection is reused, it may be necessary to deliver a location registration request message in addition to the first NAS message sent after the wireless connection is established. Therefore, the radio access point 110 needs to be changed so that it can send the INITIAL UE MESSGAE even in a situation different from the situation in which the NAS message transmitted first after the wireless connection of the terminal 100 is established. Here, as another example of the situation, there is a case in which the terminal 100 sends specific information through a ULInformationTransfer message and a case in which the RAN control element 130 informs that the terminal 100 will request a new location registration.

In addition, if the message delivered by the radio access point 110 is a UPLINK NAS TRANSPORT message, UPLINK NAS TRANSPORT is not used when sending a location registration request message in some cases, so the radio access point 110 is an IE included in the INITIAL UE MESSAGE. For example, one or more of RRC Establishment Cause, S-TMSI, CSG Id, GUMMEI, Cell Access Mode, Relay Node Indicator, GUMMEI Type, and Tunnel Information for BBF may be included in the UPLINK NAS TRANSPORT message.

5 is applied to the third embodiment of the present invention, if the location registration request message of the terminal 100 is transmitted before the timer of the RAN control element 130 expires, the RAN control element 130 establishes a radio connection. By reuse, location registration of the terminal 100 may be performed.

Next, the second problem to be solved by the present invention will be described.

The second problem is based on a case in which the terminal 100 interacts with two or more radio access points 110 and 115 as shown in FIG. 1 . When the wireless connection state with the radio access point 110 with which the terminal 100 mainly interacts deteriorates below a certain level, the terminal 100 may change the radio access point with which the terminal 100 mainly interacts through a handover process. In this case, the radio access point newly interacting mainly with the terminal 100 , that is, the target radio access point may be the radio access point 115 , which was previously interacting secondary with the terminal 100 .

In the existing handover process, a mechanism for reusing all or part of the radio connection between the radio access point 115 and the terminal 100, which previously interacted secondary with the terminal 100, is not defined. 100), there is no significant difference between the handover to the radio access point 115, which has been secondary to interacting with the terminal 100, and the handover to the radio access point that has not previously interacted with the terminal 100 at all.

On the other hand, when the radio access point 110 mainly interacting with the terminal 100 fails to start handover of the terminal in time, a radio connection failure between the terminal 100 and the radio access point 110 mainly interacting with the terminal 100 (Radio) Link Failure (RLF) or Handover Failure (HOF) may occur. The terminal 100 that has undergone RLF or HOF with the radio access point 100 with which it mainly interacts may attempt radio connection re-establishment. In this case, the target for which the terminal 100 attempts to re-establish a wireless connection may be a radio access point 115 that interacts with the terminal 100 secondaryly.

Even when the terminal 100 undergoes RLF or HOF with the radio access point 110 with which it mainly interacts, the wireless connection state between the radio access point 115 and the terminal 100 with the secondary interaction is good, so that the wireless connection continues. may be well maintained. However, the existing wireless connection re-establishment process proceeded without considering the wireless connection state between the secondary interacting radio access point 115 and the terminal 100 . Even, according to the existing wireless connection re-establishment process, wireless connection re-establishment may be performed after all the connections between the secondary interacting radio access point 115 and the terminal 100 are released.

That is, when there is a radio access point 115 that subordinately interacts with the terminal 100 in the handover process and the radio connection re-establishment process of the terminal 100 as described above, the existing radio resources are reused to provide resources. Although saving can be achieved, a mechanism that reflects this has not been defined previously.

First, with respect to the handover of the terminal 100, the terminal 100 or the radio access point 115 recognizes that the target radio access point 115 is the radio access point 115 with which the target radio access point 115 was subordinately interacted before the handover, and then An existing wireless connection may be reused to complete a wireless connection reconfiguration process.

Next, in relation to the wireless connection re-establishment of the terminal 100, the terminal 100 or the radio access point 115 is a radio access point 115 with which the wireless connection re-establishment target was previously interacted subordinately. The connection can be reused to complete the wireless connection re-establishment process.

In both of the above two methods, a necessary process is performed by reusing a radio connection with the radio access point 115 that has been subordinately interacted with in the past, thereby saving resources.

Hereinafter, an embodiment of the present invention will be described in detail in relation to handover of the terminal 100 and wireless connection re-establishment.

First, in the handover process of the terminal 100, the terminal 100 or the radio access point 115 recognizes that the target radio access point 115 is the radio access point 115 with which the target radio access point 115 was subordinately interacted before the handover, and then already exists. The wireless connection can be reused to complete the wireless connection reconfiguration process.

The terminal 100 may recognize that the target radio access point 115 is the radio access point 115 with which the target radio access point 115 was subordinately interacted before handover even with the existing mechanism. However, the target radio access point 115 may not recognize that the handover terminal 100 is the terminal 100 with which the handover terminal 100 was subordinated previously.

FIG. 6 is a diagram illustrating a process for allowing a radio access point 115 to recognize that the terminal 100 to be handed over is the terminal 100 that was serving as a secondary service according to an embodiment of the present invention related to the handover of the terminal 100 to be.

Referring to FIG. 6 , in step 610 , the radio access point 110 that mainly serves the terminal 100 , that is, the primary radio access point 110 is a message requesting that the radio access point 115 secondary service the terminal 100 . can send The name of the request message transmitted here may be SCELL ADDITION REQUEST MESSAGE. In addition, the request message may include at least one of an identifier used by the radio access point 110 to identify the terminal 100 and an identifier recommended to be used by the radio access point 115 to identify the terminal 100 . The included identifier may mean at least one of C-RNTI and eNB UE X2AP ID.

The message transmitted in step 610 may include additional information in addition to the identifier in order to successfully request the radio access point 115 to provide the secondary service to the terminal 100 . For example, a sub-identifier of the radio access point 115, bearer information desired to be serviced by the radio access point 115, access restriction information of the terminal 100, the RAN control element 130 identifier that manages the terminal 100, RAN The identifier used by the control element 130 to identify the terminal 100, the security-related capabilities of the terminal 100, AS-related security information, the aggregate maximum bit rate of the terminal 100 (Aggregate Maximum Bit Rate, AMBR) ), CSG membership status.

The lower identifier of the radio access point 115 may be expressed in the form of an E-UTRAN Cell Global Identifier (ECGI). When the radio access point 115 is an eNB, it may be necessary to send an ECGI for cell unit classification within the eNB. Meanwhile, the bearer information desired to be serviced by the radio access point 115 may include at least one of a bearer identifier and a bearer QoS parameter. If the element indicated by the lower identifier of the radio access point 115 permits the radio access point 115 to service one or more of the bearers indicated by the bearer identifier contained in the bearer information desired to be serviced, the radio access point 115 is It may be necessary to reserve the necessary resources.

The resource use restriction information of the terminal 100 may contain information about a resource that the terminal 100 cannot use or a resource that can be used. The resource use restriction information may refer to a Handover Restriction List (HRL). Since HRL is mobility-related information, new information on resource use may be used.

The radio access point 115 that has received the identifier of the RAN control element 130 that manages the terminal 100 manages the terminal 100 when it needs to interact with the RAN control element 130 for the terminal 100 . It is possible to find out the RAN control element 130 by using the RAN control element 130 identifier. Also, when the RAN control element 130 interacts with the RAN control element 130 using an identifier used to identify the terminal 100 , the terminal 100 may be identified.

The radio access point 115 prepares an AS security configuration by referring to one or more of Security Capabilities and AS-related security information of the terminal 100 .

The radio access point 115 may schedule so that the sum of the bit rates of specific bearers serving the terminal 100 does not exceed the AMBR of the terminal 100 . The specific bearer may mean all bearers that the radio access point 115 serves to the terminal 100 or all data bearers that the radio access point 115 serves to the terminal 100 .

The CSG membership status indicates the result of membership verification or access control performed by the terminal 100 or the terminal 100 and the radio access point 110 for the radio access point 115 . If the radio access point 115 determines that the CSG membership status is incorrect, the radio access point 115 may send the correct CSG membership status in step 620 or reject the request itself.

In step 620 , the radio access point 115 , that is, the secondary radio access point 115 may send a message to the radio access point 110 , accepting its secondary service to the terminal 100 . The name of the accepted message transmitted here may be SCELL ADDITION ACKNOLEDGE. In addition, the acceptance message may include an identifier to be used or used to identify the terminal 100 in the radio access point 115 . The included identifier may be at least one of C-RNTI and eNB UE X2AP ID. The acceptance message may include at least one of information on a bearer accepted by the radio access point 115 and information on a bearer not accepted by the radio access point 110 among bearers requested to be serviced by the radio access point 110 .

In step 630 , the primary radio access point 110 may send a message requesting handover of the terminal 100 to the secondary radio access point 115 . The handover request message may be a HANDOVER REQUEST message. Also, the HANDOVER REQUEST message may include an identifier received from the secondary radio access point 115 in step 20 .

In step 640 , the secondary radio access point 115 may send a handover acceptance message to the primary radio access point 110 . The handover accept message may be a HANDOVER REQUEST ACKNOWLEDGE message. In addition, the handover accept message may include a RRCConnectionReconfiguartion message, RRCConnectionReconfiguartion message may include information used for terminal 100 is omitted, at least one of a random access procedure (Random Access Procedure), uplink synchronization, uplink assignment have. This information may be expressed as a bitmap.

The RRCConnectionReconfiguartion message received from the secondary radio access point 115 may be transmitted to the terminal 100 , and accordingly, the terminal 100 may omit the random access process during the handover process to the secondary radio access point 115 .

7 shows a method of re-establishing a wireless connection by reusing a wireless connection with a radio access point 115 with which the terminal 100 secondary interacted according to an embodiment of the present invention related to the wireless connection re-establishment of the terminal 100. It is a flowchart showing the process.

Referring to FIG. 7 , in step 710 , the terminal 100 detects the RLF or HOF of the primary radio access point 110 . In addition, the terminal 100 may detect that the radio access point 115 to which the message requesting radio connection re-establishment is transmitted is the secondary radio access point 115 with which it interacted, that is, the secondary radio access point 115 . Accordingly, the terminal 100 may release the relationship with the other secondary radio access points except the secondary radio access point 115 as an initial stage of the radio connection re-establishment process.

In step 720 , the terminal 100 may send a message requesting wireless connection re-establishment to the secondary radio access point 115 . The message requesting radio connection reestablishment may be an RRCConnectionReestablishmentRequest message. In this case, the terminal 100 may omit the random access process before sending the wireless connection re-establishment request message.

The radio connection re-establishment request message may include at least one of an identifier written by the secondary radio access point 115 to identify the terminal 100 , an identifier for the secondary radio access point 115 , and a shortMAC-I for the secondary radio access point.

The identifier used to identify the terminal 100 in the secondary radio access point 115 may be a C-RNTI. The secondary radio access point 115 identifier may be a Physical Cell Identity (PCI) or ECGI. The identifier written by the secondary radio access point 115 to identify the terminal 100 and the identifier of the secondary radio access point 115 may be paired and included in the request message.

The secondary radio access point 115 may retrieve the terminal context using the terminal 100 identifier and the secondary radio access point 115 identifier contained in the request message. Additionally, the secondary radio access point 115 may be used to identify and inquire the terminal 100 using the shortMAC-I for the secondary radio access point.

In step 730 , the secondary radio access point 115 may cooperate with the primary radio access point 110 to recover terminal information. In this case, the secondary radio access point 115 may send a message requesting terminal information to the primary radio access point 110 . The primary radio access point 110 receiving the request may provide terminal information. Examples of terminal information provided by the requested primary radio access point 110 include terminal radio access capability information, AS configuration, AS context, and radio resource management (RRM) configuration.

8 is a block diagram illustrating the configuration of a terminal according to an embodiment of the present invention.

Referring to FIG. 8 , a terminal according to an embodiment of the present invention includes a transceiver 810 , a multiplexing and demultiplexing device 820 , various upper layer devices 830 , a control message processing unit 840 , and a control unit 850 . can do.

The transceiver 810 receives data and control signals from a network, ie, a radio access point, through a downlink channel, and transmits data and control signals to the network through an uplink channel.

The multiplexing and demultiplexing device 820 multiplexes the data generated by the upper layer device 830 or the control message processing unit 840 or demultiplexes the data received from the transceiver 810 to the appropriate upper layer device 830 or control message. It serves to transmit to the processing unit 840 .

The control message processing unit 840 is an RRC layer device and processes a control message received from the network to take a necessary operation. The upper layer device 830 may be configured for each service, and it processes data generated from user services and transmits it to the multiplexing/demultiplexing device 820 or processing data transmitted from the multiplexing/demultiplexing device 820 to process data It is delivered to the service application of the layer.

The controller 850 controls the transceiver 810 and the multiplexing/demultiplexing device 820 according to information received through the transceiver 810 . In addition, the control unit 850 performs a function of controlling the terminal to increase efficiency by shortening the time for the terminal to transmit a new location registration request or reusing the wireless connection according to an embodiment of the present invention.

9 is a block diagram illustrating the configuration of a radio access point, for example, a base station according to an embodiment of the present invention. Referring to FIG. 9 , the base station may include a transceiver 910 , a multiplexing and demultiplexing device 920 , an upper layer device 930 , a control message processing unit 940 , and a control unit 950 .

The transceiver 910 transmits data and control signals to the terminal through a downlink channel and receives data and control signals from the terminal through an uplink channel. Also, the transceiver 910 transmits/receives data and signals to and from other network entities connected through a wired network, and in particular, transmits/receives necessary signals to and from a RAN control element, for example, an MME according to an embodiment of the present invention.

The multiplexing and demultiplexing device 920 multiplexes the data generated by the upper layer device 930 or the control message processing unit 940 or demultiplexes the data received from the transceiver 910 to the appropriate higher layer device 930 or control message. It serves to transmit to the processing unit 940 .

The control message processing unit 940 processes the control message transmitted by the terminal to take a necessary operation, or generates a control message to be transmitted to the terminal and transmits it to a lower layer. The higher layer device 830 may be configured for each bearer, and configures the data transmitted from the S-GW or another base station as an RLC PDU and transmits it to the multiplexing and demultiplexing device 920 or from the multiplexing and demultiplexing device 920 . The delivered RLC PDU is configured as a PDCP SDU and delivered to the S-GW or other base station.

The controller 950 controls the transceiver 910 and the multiplexing/demultiplexing device 920 according to information received through the transceiver 910 . In addition, the control unit 950 releases the wireless connection of the terminal as soon as possible according to an embodiment of the present invention to shorten the time for the terminal to transmit a new location registration request or to allow the terminal to reuse the wireless connection for a predetermined time It performs the function of controlling to increase efficiency by maintaining it. Furthermore, it controls so that the terminal can reuse the radio connection with the secondary base station even in the handover and radio connection re-establishment process of the terminal.

In the above-described embodiments, all steps may be selectively performed or omitted. Also, the steps in each embodiment do not necessarily occur in order and may be reversed.

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. That is, it will be apparent to those of ordinary skill in the art to which the present invention pertains that other modified examples can be implemented based on the technical idea of the present invention.

Claims (16)

A method of a first base station of a communication system, comprising:
A second base station including a first identifier assigned by the first base station for the first base station to identify a terminal, a security-related capability of the terminal, and an aggregate maximum bit rate (AMBR) of the terminal used by the second base station transmitting an additional request message to the second base station; and
When the second base station addition is approved by the second base station, the second base station sends a second base station addition acknowledgment message including a second identifier assigned by the second base station to the second base station to identify the terminal Receiving from a base station,
The first identifier and the second identifier are used to support dual connectivity of the terminal. According to claim 1,
The second base station addition request message is a method, characterized in that it includes information about the bearer. 3. The method of claim 2,
The information on the bearer comprises an identifier of the bearer. 3. The method of claim 2,
The information on the AMBR and the bearer is characterized in that the second base station is used for resource allocation to the terminal. A method of a second base station of a communication system, comprising:
a second base station including a first identifier assigned by the first base station for the first base station to identify the terminal, a security-related capability of the terminal, and an aggregate maximum bit rate (AMBR) of the terminal used by the second base station receiving an additional request message from the first base station;
When the second base station addition is approved by the second base station, the second base station sends a second base station addition acknowledgment message including a second identifier assigned by the second base station to the first to identify the terminal transmitting to the base station;
The first identifier and the second identifier are used to support dual connectivity of the terminal. 6. The method of claim 5,
The second base station addition request message is a method, characterized in that it includes information about the bearer. 7. The method of claim 6
The information on the bearer comprises an identifier of the bearer. 7. The method of claim 6,
The method of claim 1, further comprising allocating a resource to the terminal based on the AMBR and information on the bearer. In the first base station of the communication system,
a transceiver for transmitting and receiving a signal; and
a second base station including a first identifier assigned by the first base station for the first base station to identify a terminal, a security-related capability of the terminal, and an aggregate maximum bit rate (AMBR) of the terminal used by the second base station An additional request message is transmitted to the second base station, and when the second base station addition is approved by the second base station, the second base station uses the second identifier assigned by the second base station to identify the terminal. A control unit configured to receive a second base station addition acknowledgment message including a second base station from the second base station,
The first identifier and the second identifier are used to support dual connectivity of the terminal. 10. The method of claim 9,
The second base station addition request message is a first base station, characterized in that it includes information about the bearer. 11. The method of claim 10,
The information about the bearer, the first base station, characterized in that it includes an identifier of the bearer. 11. The method of claim 10,
The information on the AMBR and the bearer is a first base station, characterized in that used for resource allocation to the terminal of the second base station. In a second base station of a communication system,
a transceiver for transmitting and receiving a signal; and
a second base station including a first identifier assigned by the first base station for the first base station to identify the terminal, a security-related capability of the terminal, and an aggregate maximum bit rate (AMBR) of the terminal used by the second base station Upon receiving the addition request message from the first base station, and when the second base station addition is approved by the second base station, the second base station receives the second identifier assigned by the second base station to identify the terminal A control unit configured to transmit a second base station addition acknowledgment message including a control unit to the first base station,
The second base station, characterized in that the first identifier and the second identifier are used to support dual connectivity of the terminal. 14. The method of claim 13,
The second base station addition request message is a second base station, characterized in that it includes information about the bearer. 15. The method of claim 14,
The information about the bearer, the second base station, characterized in that it includes an identifier of the bearer. 15. The method of claim 14,
The second base station, characterized in that the control unit is further configured to allocate resources to the terminal based on the information on the AMBR and the bearer.

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