KR20120077397A - Method for controlling overload in a mobile communication system - Google Patents

Abstract

PURPOSE: An overload controlling method of a wireless communication system is provided to perform overload control through information of an eNB or a serving gateway. CONSTITUTION: ENB information is obtained(200). The eNB to perform overload control is selected based on the eNB information(210). A message is transmitted for requesting overload control to the selected eNB(220). A response to the message is received from the selected eNB(230). The eNB information includes the number of logic connections on an SI interface.

Description

Overload control method for wireless communication system {METHOD FOR CONTROLLING OVERLOAD IN A MOBILE COMMUNICATION SYSTEM}

The present invention relates to a wireless communication system, and more particularly, to an overload control method in a mobility management entity (MME) of a wireless communication system.

In the 4G mobile communication system, the MME is a core network system node for performing authentication and authority setting procedures of a user equipment (UE) and supporting mobility of subscribers. A plurality of eNodeBs (eNBs) are present in the E-UTRAN, and the MME and the serving gateway are connected to the plurality of eNodeBs (eNBs). The eNodeB (eNB) is a radio network control station that performs radio resource management and control, mobility management, call control, and transmission network optimization. The eNodeB (eNB) is a node interworking with the 4G mobile communication core network, and is a subject for signaling in a wireless section through the LTE-Uu interface with the terminal. In addition, the eNodeB (eNB) transmits and receives all signaling related to mobility management, paging, and service of the terminal, and transmits an associated control plane signal to the MME 10 through an S1-MME interface and a user. The plane signal (user plane signal) is transmitted to the serving gateway through the S1-U interface.

When the overload situation occurs in the MME in the 4th generation mobile communication system, the first method of controlling the overload start message is delivered to the eNodeB (eNB). Branches will exist. 1) Reject an RRC access request for a non-emergency mobile originated PS service or a non-emergency mobile originated CS service. 2) Deny all newly connected EPS (Evolved Packet System) mobility management signaling. 3) Deny all RRC connections except emergency sessions.

When one of the three types is selected and delivered to the eNodeB (eNB), the corresponding eNodeB (eNB) rejects the RRC connection request of the terminal included in the reason, and the reason for rejecting the RRC connection request to the corresponding terminal. You must inform. If the overload situation of the MME is released after a certain time elapses, and there is a margin of increase in load, an overload stop message is transmitted to the eNodeB (eNB), indicating that the MME can normally process signaling.

The second method to control the overload situation is to release the existing connected connection for the UEs in ECM-CONNECTED mode due to load balancing TAU required. The disconnected terminals request an RRC connection to another MME that does not have an overload existing in the corresponding MME pool.

However, this prior art has the following problems.

First, when transmitting an overload start message for the overload control in the MME, there is no selection criteria of the eNodeB (eNB). Delivering an overload initiation message to an eNodeB (eNB) that has almost no call processing due to the nature of the eNodeB (eNB) is not helpful for solving the overload of the MME. In addition, when the overload start message is delivered to the entire eNodeB (eNB), it may be helpful for the overload control of the MME temporarily, but there is a problem in that it is unable to serve a wide range of subscribers.

In addition, in view of the currently defined standard, it is not possible to confirm whether the overload start message delivered by the MME actually arrives at the eNodeB (eNB). That is, the MME cannot confirm whether the overload control is substantially performed in the eNodeB (eNB) that requested the overload control.

Therefore, the MME needs a method of selecting when the overload start message is delivered to the eNodeB (eNB) and a method of confirming whether the eNodeB (eNB) has received the overload start message.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above, and to provide a method for overload control using information of an eNodeB (eNB) or a serving gateway.

According to an aspect of the present invention for achieving the above object, the overload control method of the wireless communication system of the present invention comprises the steps of obtaining eNodeB (eNB) information; Selecting an eNodeB (eNB) to perform overload control based on the eNodeB (eNB) information; Transmitting a message requesting overload control to the selected eNodeB (eNB); And receiving a response to the message requesting the overload control from the selected eNodeB (eNB).

According to an embodiment of the present invention for achieving the above object, the overload control method of the wireless communication system of the present invention comprises the steps of: transmitting a message requesting the termination of the overload control to the selected eNodeB (eNB); And receiving a response to the message requesting termination of the overload control from the selected eNodeB (eNB).

According to an embodiment of the present invention for achieving the above object, the overload control method of the wireless communication system of the present invention comprises the steps of obtaining the serving gateway information; And selecting a serving gateway to perform overload control based on the serving gateway information.

According to an embodiment of the present invention for achieving the above object, the overload control method of the wireless communication system of the present invention comprises the steps of: transmitting a message requesting the overload control to the serving gateway; And receiving a response to the message requesting the overload control from the serving gateway.

According to an embodiment of the present invention for achieving the above object, the overload control method of the wireless communication system of the present invention comprises the steps of: transmitting a message requesting the termination of the overload control to the serving gateway; And receiving a response to the message requesting termination of the overload control from the serving gateway.

According to the present invention, an MME, which is a mobility management node of a Long Term Evolution (LTE) core network, can effectively handle an overload situation and terminate an overload situation while providing continuous service when an overload situation occurs. Uncertainty about overload control can be resolved by adding an acknowledgment for an overload-related message to the existing operation for overload control between MME and eNodeB (eNB). In addition, blocking the paging and paging response processing procedure that causes a lot of signaling at the serving gateway can reduce the signaling of the MME and help the MME to get out of an overload situation in a shorter time.

1 is a schematic configuration diagram of a fourth generation mobile communication system.
2 is a flowchart illustrating a method for controlling overload in a mobility management entity according to an embodiment of the present invention.
3 is a diagram illustrating a method for obtaining eNodeB (eNB) identification information according to an embodiment of the present invention.
4 is a diagram illustrating a method for obtaining the number of logical connections on an S1 interface according to an embodiment of the present invention.
5 is a diagram illustrating a method for obtaining a number of logical connections on an S1 interface according to another embodiment of the present invention.
6 is a diagram illustrating a method for transmitting an overload control request message to an eNodeB (eNB) according to an embodiment of the present invention.
7 is a diagram illustrating a method for transmitting an overload control termination message to an eNodeB (eNB) according to an embodiment of the present invention.
8 illustrates a method for transmitting an overload control request message to a serving gateway according to an embodiment of the present invention.
9 illustrates a method for transmitting an overload control termination message to a serving gateway according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The terms or words used in the specification and claims described below should not be construed as being limited to the ordinary or dictionary meanings, and the inventors are appropriate to the concept of terms in order to explain their invention in the best way. It should be interpreted as meanings and concepts in accordance with the technical spirit of the present invention based on the principle that it can be defined. Therefore, the embodiments described in the present specification and the configuration shown in the drawings are only one embodiment of the present invention, and do not represent all of the technical idea of the present invention, and various equivalents may be substituted for them at the time of the present application. It should be understood that there may be variations and examples.

1 is a schematic configuration diagram of a fourth generation mobile communication system.

Referring to FIG. 1, the fourth generation mobile communication system includes an MME 10, a terminal 20, an E-UTRAN 30, and a serving gateway 40.

2 is a flowchart illustrating an overload control method in a mobility management entity according to an embodiment of the present invention.

Referring to FIG. 2, in step 200, eNodeB (eNB) information is obtained.

The eNodeB (eNB) information may include eNodeB (eNB) identification information, the number of logical connections on the S1 interface, the number of signaling on the S1 interface during a predefined time, the overload control priority, whether the overload control request and the overload operation class information. .

Examples of eNodeB (eNB) information are presented in Table 1 below.

Example of eNodeB (eNB) information index eNodeB (eNB) identification Number of logical connections on the S1 interface Number of signaling on S1 interface Overload control rank Overload control request Overload operating class One eNodeB1 300 900 2 Yes 2 2 eNodeB2 200 300 4 No - 3 eNodeB3 200 500 3 No - 4 eNodeB4 100 200 5 No - 5 eNodeB5 400 1200 One Yes 2

The eNodeB (eNB) identification information consists of a mobile country, a mobile network and an eNodeB (eNB) identification number. 3 is a diagram illustrating a method of obtaining eNodeB (eNB) identification information according to an embodiment of the present invention. Referring to FIG. 3, when a Stream Control Transmission Protocol (SCTP) connection is made between the eNodeB (eNB) and the MME 10, the eNodeB (eNB) sends an S1 Setup Request along with its configuration information to the MME (S1 Setup Request). 10) can be delivered. In this case, the included data may include eNodeB (eNB) identification information. If the S1 setting is normally processed, the MME 10 may generate a table for overload control together with configuration information on the corresponding eNodeB (eNB).

The number of logical connections on the S1 interface refers to the number of logical connections between the eNodeB (eNB) and the MME 10 created on the S1 interface for providing a service to a specific subscriber in real time, and is updated every time when the network is created or deleted. 4 is a diagram illustrating a method for obtaining the number of logical connections on an S1 interface according to an embodiment of the present invention. Referring to FIG. 4, an ENB UE S1 Application Protocol (S1AP) ID is allocated in an eNodeB (eNB) for a specific UE, and an initial UE message (INITIAL UE MESSAGE) is transmitted to the MME 10. After receiving the corresponding S1AP message, the MME 10 may allocate an MME 10 UE S1AP ID for the corresponding subscriber and increase the number of logical connections for the eNodeB (eNB) in which the initial UE message has occurred.

5 is a diagram illustrating a method for obtaining the number of logical connections on an S1 interface according to another embodiment of the present invention. Referring to FIG. 5, when a UE context release request (UE CONTEXT RELEASE REQUEST) initiated in an eNodeB (eNB) occurs or when a logical connection is to be deleted in the MME 10, the MME 10 may request a UE context release command ( The UE CONTEXT RELEASE COMMAND is transmitted to the eNodeB (eNB) to request the deletion of the logical connection to the eNodeB (eNB). When the MME 10 receives a UE context release completion or a timeout occurs, the MME 10 may consider the corresponding UE-related logical connection to be deleted and reduce the number of logical connections. That is, the number of logical connections can be reduced when the release process occurs for the existing logical connections. However, if all logical connections of the associated eNodeB (eNB) are lost due to reset, SCTP disconnection, etc., it may be initialized to 0 as in the initial start.

The number of signaling on the S1 interface for a predefined time refers to the number of signaling transmitted and received with the corresponding eNodeB (eNB) for a predefined time (eg, 1 minute). The measurement time may change depending on the signaling environment. Information can be obtained by measuring a UE-related S1AP message transmitted and received with a specific eNodeB (eNB) for a predefined time, and after a predefined time, update the number of signaling for the corresponding eNodeB (eNB) and initialize the measurement value. can do. The message for increasing the number of times may be limited to the UE related service and measured. Services related to a specific UE include E-RAB management functions, initial context transfer functions, UE capability info indication functions, mobility functions such as handover, paging, NAS It may include a signaling signaling function (NAS signaling transport function), S1 UE context release function (S1 UE context release function), status transfer (status transfer) and the like.

The overload control rank may be calculated based on the number of logical connections on the S1 interface and the number of signaling on the S1 interface for a predetermined time, and when overload occurs, overload control may be performed according to the corresponding rank. The selection period and the method of using the two data can be determined by the operator operating the MME 10. For example, the sum of the two values indicates that the eNodeB (eNB) having the highest value has the highest priority. Can be utilized. It can also be calculated by weighting the two data. Since the eNodeB (eNB) with the highest number of signaling and the most logical connections can be regarded as causing the most load on the system, it is determined that the first control is necessary for overload control. Can be.

Whether to request the overload control is to record whether the overload control is requested to the corresponding eNodeB (eNB). If the eNodeB (eNB) is notified that the overload control has been started, an indication is made to prevent re-request for overload control of the same operation. It can be logged to deliver OVERLOAD STOP message after overload release.

The overload operation class may indicate an overload operation to be performed by the eNodeB (eNB).

Referring back to FIG. 2, in step 210, an eNodeB (eNB) to select an overload control is selected based on the eNodeB (eNB) information. eNodeB in consideration of eNodeB (eNB) information such as eNodeB (eNB) identification information, the number of logical connections on the S1 interface, the number of signaling on the S1 interface for a predefined time, the overload control rank, whether the overload control is requested or the overload operation class information. (eNB) can be selected.

In step 220, a message for requesting overload control is transmitted to the selected eNodeB (eNB). 6 is a diagram illustrating a method for transmitting an overload control request message to an eNodeB (eNB) according to an embodiment of the present invention. Referring to FIG. 6, the MME 10 transmits an OVERLOAD START message to the eNodeB (eNB). The message for requesting overload control may include overload operation information of the eNodeB (eNB). Examples of overload operations are shown in Table 2 below.

Example of overload operation Overload operating class Overload operation 1 (minor) Deny all RRC access for non-emergency terminal data transmission 2 (major) Deny all RRC connections for signaling 3 (critical) Only allow RRC access for emergency sessions

In Table 2, the examples are divided into three classes, which can be divided more or less internally. The mapping relationship between the overload operation class and the overload operation may be arbitrarily set by the operator of the MME 10, and the same overload operation may exist according to the overload operation class.

Referring back to FIG. 2, in step 230, a response to a message for requesting overload control is received from the selected eNodeB (eNB). Referring to FIG. 6, the MME 10 receives an OVERLOAD START ACKNOWLEDGE message from an eNodeB (eNB). By using the response message to the message requesting the overload control, it is possible to check whether the selected eNodeB (eNB) has received the message requesting the overload control, so as to re-select another eNodeB (eNB) to perform the overload control. It is easy to judge. After receiving the overload start approval message from the eNodeB (eNB), the MME 10 may update the eNodeB (eNB) information by indicating that the corresponding eNodeB (eNB) is performing overload control and displaying the delivered overload operation together. . The indication of the overload action is the same when the overload start message is compared with the previous overload action and the current overload action when the overload start message needs to be delivered again. In order not to pass.

7 is a diagram illustrating a method for transmitting an overload control termination message to an eNodeB (eNB) according to an embodiment of the present invention.

Referring to FIG. 7, the MME 10 transmits an OVERLOAD STOP message requesting the termination of overload control to the selected eNodeB (eNB), and sends a message to request a termination of the overload control from the selected eNodeB (eNB). You may receive an OVERLOAD STOP ACKNOWLEDGE message in response. The MME 10 checks whether the overload control has been performed before the overload stop message is transmitted to the eNodeB (eNB) through the overload control of Table 1, and targets only the eNodeB (eNB) being controlled. An overload abort message can be delivered. After receiving the overload stop grant message from the eNodeB (eNB), it can be indicated by N in the overload control of Table 1 that the eNodeB (eNB) has finished the overload control.

8 is a diagram illustrating a method for transmitting an overload control request message to a serving gateway according to an embodiment of the present invention.

Referring to FIG. 8, the MME 10 transmits an OVERLOAD START message to the serving gateway 40 and receives an OVERLOAD START ACKNOWLEDGE message from the serving gateway 40. The serving gateway information may be updated after receiving the overload start approval message from the serving gateway 40.

The MME 10 may maintain a table that stores information necessary for requesting the overload control to the serving gateway 40. Table 3 is an example of such a table.

Example of serving gateway information index Serving Gateway IP Address Information Number of sessions opened Overload control rank Overload control Overload operating class One 1.1.1.1 300 One Yes 2 2 2.2.2.2 200 2 No - 3 3.3.3.3 100 3 No -

The MME 10 may maintain session information for each serving gateway 40 whenever a session for a subscriber is established, and may redefine the overload control rank whenever the session establishment information is updated. Table 3 shows the overload control order in order of increasing number of sessions as an example to simplify the table. Whether overload control and class can be handled in the same manner as overload control and class for the eNodeB (eNB).

The serving gateway 40 receives an overload initiation message from the MME 10, and then delivers a downlink data notification message when downlink data arrives to reduce signaling to the MME 10. And fail due to no resource available. In addition, a bearer request generated by the PDN gateway may be failed. Refer to 3GPP TS23.401 FIG. 5.4.1-1 for the bearer creation request procedure requested by the PDN gateway.

9 is a diagram illustrating a method for transmitting an overload control termination message to a serving gateway according to an embodiment of the present invention.

Referring to FIG. 9, the MME 10 transmits an OVERLOAD STOP message requesting the termination of the overload control to the serving gateway 40, and sends a message to the message requesting the termination of the overload control from the serving gateway 40. You may receive an OVERLOAD STOP ACKNOWLEDGE message in response.

The MME 10 may check whether the overload control was previously performed before the overload stop message was transmitted to the serving gateway 40 through the overload control of Table 3, and only the serving gateway being controlled. An overload abort message can be delivered.

The serving gateway information may be updated after receiving the overload stop acknowledgment message from the serving gateway 40. For example, it can be indicated by N in the overload control of Table 3 that the serving gateway 40 has finished the overload control.

While the invention has been described using several embodiments, these embodiments are illustrative and not restrictive. As such, those of ordinary skill in the art will appreciate that various changes and modifications can be made to the present disclosure without departing from the spirit of the invention and the scope of the rights set forth in the appended claims. .

10: MME
20: UE
30: E-UTRAN
40: serving gateway

Claims (16)

As an overload control method of a wireless communication system,
obtaining eNodeB (eNB) information;
Selecting an eNodeB (eNB) to perform overload control based on the eNodeB (eNB) information;
Transmitting a message requesting overload control to the selected eNodeB (eNB); And
Receiving a response to the message requesting the overload control from the selected eNodeB (eNB)
Overload control method comprising a. The method of claim 1,
The eNodeB (eNB) information includes the number of logical connections on the S1 interface. The method of claim 1,
The eNodeB (eNB) information includes the number of signaling on the S1 interface for a predefined time. The method of claim 1,
The eNodeB (eNB) information includes an overload control priority. The method of claim 4, wherein
The overload control method is calculated based on the number of logical connections on the S1 interface and the number of signaling on the S1 interface for a predefined time. The method of claim 1,
The eNodeB (eNB) information includes an overload control method including whether to request an overload control. The method of claim 1,
The eNodeB (eNB) information includes overload operation class information. The method of claim 1,
The message for requesting overload control includes overload operation information for the selected eNodeB (eNB). The method of claim 1,
Updating the eNodeB (eNB) information after receiving a response to the message requesting the overload control. The method of claim 1,
Transmitting a message requesting termination of overload control to the selected eNodeB (eNB); And
Receiving a response to the message requesting termination of the overload control from the selected eNodeB (eNB)
Overload control method further comprising. The method of claim 10,
And updating the eNodeB (eNB) information after receiving a response to the message requesting termination of the overload control. The method of claim 1,
Obtaining serving gateway information; And
Selecting a serving gateway to perform overload control based on the serving gateway information;
Overload control method further comprising. The method of claim 12,
Transmitting a message requesting overload control to the serving gateway; And
Receiving a response to the message requesting the overload control from the serving gateway
Overload control method further comprising. The method of claim 13,
And updating the serving gateway information after receiving a response to the message requesting the overload control from the serving gateway. The method of claim 13,
Sending a message requesting termination of overload control to the serving gateway; And
Receiving a response from the serving gateway to a message requesting termination of the overload control
Overload control method further comprising. 16. The method of claim 15,
And updating the serving gateway information after receiving a response to the message requesting the termination of the overload control from the serving gateway.

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