JP6121672B2 - Mobile communication system and mobile communication method - Google Patents

Description

  The present invention relates to a mobile communication system and a mobile communication method, and more particularly to a mobile communication system and a mobile communication method that effectively use resources between a radio base station and a mobility management station.

  Coupled with the rapid spread of smartphones with advanced functions of mobile terminals, services using the LTE (Long Term Evolution) method, which is a technology for realizing ALL-IP (Internet Protocol) / broadbanding of mobile networks, have been introduced. The LTE system is a mobile communication system standardized by 3GPP (3rd Generation Partnership Project).

  A radio access network based on the LTE scheme is composed of a mobility management station (MME) and a radio base station (eNB: evolved Node B / HeNB: Home evolved Node B) positioned as part of the core network. And a mobile terminal (UE: User Equipment) connects with eNB / HeNB by a radio link. In the following description, the mobility management station will be referred to as “MME”, the radio base station as “eNB”, and the mobile terminal as “UE”.

  The UE includes a radio interface and is connected to the eNB through a radio link within the service area of the eNB. An eNB is an entity (node) that terminates a radio interface with a UE. That is, the eNB has a call admission control function when the UE is directly connected to the UE through a radio link and a call is transmitted from the UE, a paging function that calls the UE when there is an incoming call, and the like. The MME is an entity (logical node) that performs call connection control and standby position (mobility) management of the UE and performs bearer management, NAS (Non-Access-Stratum) signaling processing, and the like. is there.

  The UE is connected to the eNB through the LTE-Uu interface, and performs radio processing between the UE and the eNB by performing handover processing, radio bearer setting, cancellation, and the like by RRC (Radio Resource Control).

  The MME connects to the eNB via the S1-MME interface, exchanges control plane information with the eNB via S1-AP (S1 Application Protocol), and sets related parameters of the eNB. Packet call connection, authentication processing, security processing, standby position registration processing, and the like are performed by the NAS, which is a functional layer between the UE and the MME.

  Further, LTE call control is based on the concept of always-on connection, a bearer is set as soon as the UE is turned on, and an IP address is allocated to the UE, enabling IP communication in the same way as a fixed communication network (described later). reference).

  FIG. 1 shows a protocol stack of a control plane for transmitting a call and a signal for controlling the network in such a radio access network of the LTE system.

  Between the UE and the eNB, in order from the upper layer, RRC, PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Media Access Control), and physical layer (L1) are configured.

  Further, between the eNB and the MME, in order from the upper layer, are configured by S1-AP, SCTP (Stream Control Transport Protocol), IP, data link layer (L2), and physical layer (L1). SCTP is a transport layer protocol for transferring telephone network control signals over an IP network.

  A technique relating to such a protocol stack is disclosed in Patent Document 1. The technique disclosed in Patent Document 1 proposes a protocol stack that allows a target UE to measure and report desired radio quality. A “Drive Test” is performed to measure and investigate radio quality. The technology disclosed in Patent Document 1 is a technology related to a “MDT (Minimisation of Drive Tests)” method that causes a target UE to measure and report desired radio quality. The function of processing the RRC protocol in the target UE and eNB does not delete “UE Context” including “MDT policy” applied in the target UE even when the target UE transitions to the RRC_Idle state. It is configured.

  Patent Document 2 discloses a technique for efficiently connecting a relay node (RN) between a UE and a DeNB (Donor evolved Node B) in an LTE-Advanced system that is a successor of the LTE system. Is described. The technique described in Patent Literature 2 is configured such that the DeNB performs the S1 protocol setting process with the MME instead of the RN. In the RN attach process, the DeNB notifies the MME of predetermined information. As a result, it is possible to efficiently connect the RN to the DeNB by omitting some of the conventional processing steps.

JP 2011-223119 A JP 2011-023873

  FIG. 2 is a sequence diagram illustrating an attach processing procedure performed when the UE is powered on in the LTE scheme. The HSS (Home Subscriber Server) shown in the figure is a subscriber information database in the mobile communication network, and manages authentication information and location information. An S-GW (Serving Gateway) is a packet gateway that accommodates an access network and controls transfer of user data packets in a user plane. A P-GW (Packet data network Gateway) is a gateway serving as a connection point with a packet data network, and performs IP address assignment, packet transfer to the S-GW, and the like.

  First, the UE that has been powered on sets up a radio control link for transmitting and receiving control signals to and from the eNB (S101). Then, an attach request is transmitted to the MME (S102).

  The UE and the MME perform authentication and concealment, and the MME registers the location with the HSS and stores that the UE is connected as a subordinate of the MME (S103).

  Subsequently, the MME transmits a bearer setting request to the S-GW to start setting a communication path for the UE. Thereby, path setting and IP address assignment to the UE are performed between the S-GW and the P-GW. And S-GW prepares the radio access bearer of eNB direction from S-GW, and returns a bearer setting response with respect to MME. (S104).

  The MME transmits a context setting request to the eNB, and notifies the information element received from the S-GW and the IP address of the UE (S105). The context setting request includes an attach completion notification that is a response to the attach request.

  The eNB performs setting of the radio data link and transmits an attach completion notification to the UE (S106). Also, the eNB sets a radio access bearer in the S-GW direction from the eNB, and returns a context setting response to the MME (S107).

  In the process from S105 to S107, communication path information and communication control information regarding the target UE are set in the MME and eNB.

  The UE that has received the attach completion notification in S106 returns an attach completion response to the MME (S108).

  The MME that has received the context setting response and the attach completion response transmits a bearer update request to the S-GW, and notifies the information element received from the eNB included in the context setting response. The S-GW sets a radio access bearer in the eNB direction from the previously prepared S-GW, and returns a bearer update response to the MME (S109).

  Through the above processing, the communication path from the UE to the P-GW is set, and the UE to which the IP address is assigned can perform IP communication in the same manner as the fixed communication network. If the UE does not perform communication for a certain period of time, the radio control link, the radio data link, and the radio access bearer are released, but the communication path of the core network is maintained.

  As described above, when the UE non-communication state continues for a certain period of time, radio resources are released. However, the control signal interface (S1-MME interface) between the eNB and the MME remains maintained.

  Transmission of control signals between the eNB and the MME in the LTE scheme operates on the SCTP protocol. Even when the user is sleeping at night or the like and the UE is in a no-communication state, the SCTP connection remains established between the eNB and the MME in order to confirm the existence of the opposite node and to maintain the communication path information. ing.

  Thus, it is conceivable that the SCTP connection is disconnected when the UE is not in communication to release unnecessary resources between the eNB and the MME. However, when the SCTP connection is disconnected, the upper interface S1-AP also needs to be disconnected. When S1-AP is disconnected, context information such as eNB information (communication path information, communication control information) set during the attach process described above is deleted from the MME, which corresponds to a sudden call or incoming call. I can't.

  In this way, between the eNB and the MME, even when the UE is in a no-communication state, resources related to the interface of the control signal are still captured and cannot be released. Therefore, in an environment where the bandwidth of the transmission section between the eNB and the MME is narrow, or in an environment where the number of installed eNBs is larger than the number of installed MMEs, the eNB and the MME in a time zone in which no traffic occurs. Improvement for effective utilization of resources is desired.

  Further, neither of Patent Documents 1 and 2 above describes a description regarding releasing resources between the eNB and the MME when the UE is in a no-communication state.

  In view of the above-described problems, an object of the present invention is to provide a mobile communication system and a mobile communication method that can effectively use resources by deleting a useless connection between an eNB and an MME when a UE is not in communication. It is to provide.

  To achieve the above object, a mobile communication system according to an aspect of the present invention includes a radio base station connected to a mobile terminal via a first link, and a radio base station connected to the radio base station via a second link. A mobility management station that controls call connection of the mobile terminal and manages a position (mobility) during standby, and each of the radio base station and the mobility management station does not perform communication by the mobile terminal for a predetermined time. The present invention relates to a reservation execution means for executing a reservation process that disconnects the connection of the first protocol of the second link and resets it when a predetermined event occurs, and the execution of the reservation process. Information is sent and received between the radio base station and the mobility management station using a message of the second protocol of the second link. A message transmission / reception unit that holds the context information including connection information and connection control information related to the mobile terminal when the connection is disconnected, and resets the connection. Is characterized in that the held context information is used.

  The mobile communication method according to another aspect of the present invention includes a radio base station connected to a mobile terminal via a first link, and a call connection control of the mobile terminal connected to the radio base station via a second link. And the connection of the first protocol of the second link when the mobile terminal is in a non-communication state in which communication by the mobile terminal is not performed for a predetermined time with the mobility management station that manages the position (mobility) at the standby time. The radio base station using the second protocol message of the second link to define the execution of the preservation process to be reset when a predetermined event occurs, and to specify information related to the execution of the preservation process. Between the mobile terminal and the mobility management station, and when the connection is disconnected by executing the preservation process, Holds context information includes connection information and connection control information, which is characterized by using the context information that the holding is when reconfiguring the connection.

  The present invention can effectively use resources by deleting a useless connection between a radio base station and a mobility management station when a mobile terminal is not communicating.

It is a figure which shows the protocol stack of the control plane in a radio access network of a LTE system. It is a sequence diagram which shows the attachment process procedure of a LTE system. It is a block diagram which shows the structure of the mobile communication system of the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the mobile communication method of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the mobile communication system of the 2nd Embodiment of this invention. It is a sequence diagram which shows the process regarding the setting of the start time / end time of a preservation process. It is a state transition diagram which shows the state transition of S1 interface, and the related operation | movement of eNB. It is a state transition diagram which shows the state transition of S1 interface, and the related operation | movement of MME. It is a sequence diagram which shows the flow of a process when the end time of a preservation process is detected during execution of a preservation process. It is a sequence diagram which shows the flow of a process at the time of detecting the call of UE during execution of a preservation | save process. It is a sequence diagram which shows the flow of a process at the time of detecting the incoming call to UE during execution of a preservation | save process. It is a sequence diagram which shows the flow of the process which changes the setting of the start time / end time of a preservation process from the MME side. It is a sequence diagram which shows the flow of the process which changes the setting of the start time / end time of a preservation process from eNB side.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  Note that the embodiment is an exemplification, and the disclosed invention is not limited to the structure of the following embodiment.

  First, a first embodiment that is a basic embodiment of the present invention will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a block diagram illustrating a configuration of the mobile communication system according to the first embodiment of this invention.

  A mobile communication system 1 according to the first embodiment includes a radio base station 10 connected to a mobile terminal 30 via a first link, and a mobility management station 20 connected to the radio base station 10 via a second link. Including. The mobility management station 20 performs call connection control of the mobile terminal 30 and position (mobility) management during standby.

  The radio base station 10 and the mobility management station 20 are configured to include message transmission / reception means 11 and 21 and preservation (preservation) execution means 12 and 22, respectively. The preservation execution means 12 and 22 disconnect the connection of the first protocol of the second link when no communication is performed by the mobile terminal 30 for a predetermined time, and reset when a predetermined event occurs. The preservation process to be executed is executed. The message transmission / reception means 11 and 21 transmit / receive information related to execution of the preservation process between the radio base station 10 and the mobility management station 20 using a message of the second protocol of the second link.

  And the preservation | save execution means 12 and 22 hold | maintain the context information of the mobile terminal 30 when disconnecting the said connection, and use the hold | maintained context information when resetting the connection. The context information includes connection information related to the mobile terminal 30 and connection control information.

  FIG. 4 is a flowchart showing the operation of the mobile communication method according to the first embodiment of the present invention.

  In the mobile communication method according to the first embodiment of the present invention, first, execution of a preservation process is defined between a radio base station and a mobility management station (S10).

  The radio base station is connected to the mobile terminal through the first link. The mobility management station is connected to the radio base station via the second link, and performs call connection control of the mobile terminal and position (mobility) management during standby. Preservation processing refers to disconnecting the connection of the first protocol of the second link when no communication is performed by the mobile terminal for a predetermined time, and resetting when a predetermined event occurs. It is processing to do. Then, the time zone for which the preservation process is executed is defined for each mobile terminal.

  Information related to the execution of the preservation process is transmitted and received between the radio base station and the mobility management station using the second protocol message of the second link (S20).

  When the connection is disconnected by executing the preservation process, context information including connection information and connection control information related to the mobile terminal is held. Further, when the connection is reset, the held context information is used (S30).

  As described above, in the present embodiment, when the mobile terminal is in a no-communication state, the first protocol connection of the link (second link) between the radio base station and the mobility management station is disconnected, and a predetermined event Introduced a preservation process that resets when an error occurs. Information related to the execution of the preservation process is configured to be transmitted and received between the radio base station and the mobility management station using a message of the second protocol of the second link. Therefore, the mobile communication system according to the present embodiment can effectively use resources by deleting a useless connection between a radio base station and a mobility management station when the mobile terminal is not in communication.

  Further, by executing the preservation process, the context information of the mobile terminal is retained when the connection is disconnected, and the retained context information is used when resetting the connection. Therefore, even if the connection of the second link is disconnected, it can be recovered early when an event that requires resetting occurs.

  Next, a second embodiment will be described.

  FIG. 5 is a block diagram showing the configuration of the mobile communication system according to the second embodiment of the present invention.

  The mobile communication system 2 according to the second embodiment includes an eNB 100 that is a radio base station, an MME 200 that is a mobility management station, and a UE 300 that is a mobile terminal.

  The UE 300 is connected to the eNB 100 through a radio interface.

  The eNB 100 includes a message input / output unit 111, a message analysis processing unit 112, a state transition processing unit 121, an MME information management unit 122, and a timer management unit 123. The MME 200 includes a message input / output unit 211, a message analysis processing unit 212, a state transition processing unit 221 and a mobility management unit 222.

  Note that the message input / output unit 111 and the message analysis processing unit 112 surrounded by a dotted line correspond to the message transmitting / receiving unit 11 of the first embodiment. Then, the state transition processing unit 121, the MME information management unit 122, and the timer management unit 123 surrounded by a dotted line correspond to the preservation execution unit 12 of the first embodiment. Similarly, the message input / output unit 211 and the message analysis processing unit 212 correspond to the message transmission / reception means 21 of the first embodiment, and the state transition processing unit 221 and the mobility management unit 222 execute the preservation of the first embodiment. Corresponds to means 22.

  The eNB 100 and the MME 200 are connected by an S1-MME interface, and SCTP is used as a transport layer protocol and S1-AP is used as an upper layer protocol. In the following description, the S1-MME interface is simply referred to as the S1 interface.

  The message input / output units 111 and 211 transmit and receive messages to be described later between the eNB 100 and the MME 200 in order to realize the preservation function.

  The message analysis processing units 112 and 212 input information based on the received message to the state transition processing units 121 and 221 and execute the processing determined by the state transition processing units 121 and 221.

  The state transition processing units 121 and 221 determine a processing method to be executed based on a received message or a detection event, and manage a transition state of an S1 interface described later.

  The MME information management unit 122 manages the time (start time / end time) related to the preservation process for each UE. The time information for each UE is notified to the MME 200. In addition, in conjunction with the state transition processing unit 121, the state of the S1 interface is managed.

  As will be described later, the mobility management unit 222 manages the time (start time / end time) regarding the reservation processing for each UE notified from the eNB 100. Further, in conjunction with the state transition processing unit 221, the state of the S1 interface is managed.

  The timer management unit 123 performs time management related to execution of the preservation process.

  Next, messages used for realizing the preservation process will be described. As described above, when the UE 300 is not in communication, the SCTP connection of the S1 interface is disconnected to release resources, and when a predetermined event is detected, the process of resetting the SCTP connection is referred to as a preservation process.

  As a message used for the preservation process, an existing message of S1-AP and a newly defined message are used.

  As an existing message, S1 Setup (S1 Setup) and Configuration Update (Configuration Update) are used.

  The S1 setup is a message used for exchanging application level data required in the eNB 100 and the MME 200 in order to correctly communicate in the S1 setup procedure between the eNB 100 and the MME 200.

  The configuration update is a message used to update eNB information or MME information that has been set in S1 setup between the eNB 100 and the MME 200. When the eNB information is updated, an eNB configuration update is transmitted from the eNB 100 to the MME 200. Conversely, when updating the MME information, the MME configuration update is transmitted from the MME 200 to the eNB 100.

  In this embodiment, time information related to the preservation process for each UE is added to these existing messages as a new parameter.

  That is, although details will be described later, the eNB 100 notifies the MME 200 of the reservation processing start time and end time for each UE using the S1 setup, and the eNB 100 and the MME 200 manage the time information, respectively.

  Further, when it is necessary to update the time information managed by each, the update is notified to the other party using configuration update. For example, when changing the time information managed by the eNB 100, the change information is notified to the MME 200 by the eNB configuration update. The MME 200 changes the managed time information to the notified time information. Similarly, when changing the time information managed by the MME 200, the change information is notified to the eNB 100 by MME configuration update. The eNB 100 changes the managed time information to the notified time information. This configuration update is used when the communication tendency of the user changes greatly and the time zone when no communication is performed is changed.

  There are the following four messages as newly defined messages.

  S1 preservation request (S1 Preservation Request), S1 preservation response (S1 Preservation Response), S1 wakeup request (S1 Wake up Request), S1 wake up response (S1 Wake up Response).

  These messages are newly added as S1 Preservation messages (S1 Preservation) for the preservation process.

  The S1 reservation request is a message that the eNB 100 transmits to notify the MME 200 when it is time to start a preset reservation process.

  The S1 reservation response is a message that is transmitted in order to reply from the MME 200 to the eNB 100 that the reservation process has been approved when the MME 200 receives the S1 reservation request from the eNB 100. When the eNB 100 receives the S1 reservation response from the MME 200, the eNB 100 disconnects the SCTP connection. When the SCTP connection is disconnected, the S1 interface enters a sleep state.

  The S1 wakeup request is a message notifying that the preservation process is to be terminated when the eNB 100 or the MME 200 detects a predetermined event when the S1 interface is in the sleep state. That is, the S1 wake-up request is a message notifying the other device that the sleep period has ended. As the predetermined event, there is a case where the end time of the preservation process managed by the eNB 100 is detected, a call from the UE 300 is detected, and an MME 200 detects an incoming call from the network to the UE 300. . When the eNB 100 detects the end time of the preservation process and when the eNB 100 detects a call from the UE 300, the eNB 100 transmits the message to the MME 200. When the MME 200 detects an incoming call from the network to the UE 300, the MME 200 transmits the message to the eNB 100.

  The S1 wakeup response is a message that is transmitted by the MME 200 or eNB 100 that has received the S1 wakeup request to reply to the eNB 100 or MME 200 that has transmitted the S1 wakeup request that the wakeup has been approved. After the transmission / reception of the message, the eNB 100 and the MME 200 set the S1 interface to an on-service state.

  Next, the flow of the preservation process will be described.

  First, the setting of the start time / end time of the preservation process will be described with reference to FIG.

  FIG. 6 is a sequence diagram showing processing relating to setting of the start time / end time of the preservation processing according to the present embodiment.

  This process is performed during the attach process that is performed when the UE is powered on, as described with reference to FIG. That is, it is performed in the S1 setup procedure between the eNB 100 and the MME 200.

  When the SCTP connection corresponding to the target UE 300 is established (S201), information is exchanged between the eNB 100 and the MME 200 by the S1-AP message of the higher layer.

  First, an S1 setup request is transmitted from the eNB 100 to the MME 200 (S202). As described above, the S1 setup request includes information defining the start / end time of the preservation process for the target UE 300 as an additional parameter. Therefore, the MME 200 that has received the S1 setup request registers the start time / end time of the preservation process for the notified UE 300 in the mobility management unit 222. Then, an S1 setup response is transmitted to the eNB 100 in order to reply that the preservation process has been approved (S203).

  The eNB 100 that has received the S1 setup response from the MME 200 sets a timer for the preservation process corresponding to the UE 300 in the timer management unit 123 and starts it (S204).

  Through the above processing, the start time / end time of the reservation processing of each UE 300 is registered and managed in the MME information management unit 122 in the eNB 100 and in the mobility management unit 222 in the MME 200, respectively.

  The start time / end time of the preservation process may be arbitrarily determined.

  For example, in the eNB 100, a communication monitoring unit (not shown) constantly monitors the communication state of each UE, accumulates a log of time from disconnection to the next call, and enters a no-communication state. You may comprise so that the time slot | zone with the highest probability may be determined statistically. Moreover, you may comprise so that it may determine based on the report from a user. Further, the MME 200 may determine by performing the statistical processing described above.

  In this way, the S1 setup procedure between the eNB 100 and the MME 200 is completed by the transmission / reception of the S1 setup request and the S1 setup response, and the S1 interface enters an on-service state.

  Next, the state transition of the S1 interface and the operations of the eNB 100 and the MME 200 related thereto will be described.

  FIG. 7 is a state transition diagram showing the state transition of the S1 interface and the related operation of the eNB 100. FIG. 8 is a state transition diagram showing state transition of the S1 interface and related operations of the MME.

  By introducing the preservation process, the S1 interface has two states, an on-service state and a sleep state. The in-service state is a state in which the SCTP connection is connected and the service can be provided at any time, and the sleep state is a state in which the SCTP connection is disconnected and resources are released.

  With reference to FIG. 7, the state transition of the S1 interface and the operation of the eNB 100 related thereto will be described.

  As described with reference to FIG. 6, the start time of the preservation process of each UE 300 is managed. And if the MME information management part 122 of eNB100 detects the start time of the preservation | save process with respect to a certain UE300 by the timer information of the timer management part 123 (1-1), the S1 reservation request | requirement with respect to the UE300 will be transmitted to MME200. That is, the MME information management unit 122 inputs an event of timer information to the state transition processing unit 121. The state transition processing unit 121 instructs the message analysis processing unit 112 to transmit the S1 reservation request because the transition state of the S1 interface of the target UE 300 being managed is the in-service state. Then, the S1 reservation request is transmitted from the message input / output unit 111.

  The MME 200 that has received the S1 reservation request transmits an S1 reservation response in order to reply to the eNB 100 that the reservation request has been approved. The eNB 100 receives this S1 preservation response (1-2). When the eNB 100 receives the S1 reservation response from the MME 200, the eNB 100 disconnects the SCTP connection. The S1 interface enters a sleep state due to the disconnection of the SCTP connection. That is, the message analysis processing unit 112 inputs the S1 reservation response notified from the message input / output unit 111 to the state transition processing unit 121. The state transition processing unit 121 instructs the message analysis processing unit 112 to disconnect the SCTP connection because the transition state of the managed S1 interface is the in-service state. Then, the S1 interface is shifted to the sleep state.

  At this time, both the eNB 100 and the MME 200 hold the context information including the IP address, port number, tracking area identifier, eNB identifier, and the like without deleting them.

  When the S1 interface is in the sleep state, when the eNB 100 detects a predetermined event, the eNB 100 resets the SCTP connection and returns the S1 interface to the in-service state.

  First, the first event is a case where the preset time of the preservation process is detected by the timer information of the timer management unit 123 (1-3a). The second event is a case where it is detected that the UE 300 has made a call from the radio link connected to the UE 300 (1-3b).

  In each case, the eNB 100 resets the SCTP connection and transmits an S1 wakeup request to the MME 200. That is, the first event or the second event is input to the state transition processing unit 121. The state transition processing unit 121 instructs the message analysis processing unit 112 to reset the SCTP connection and transmit the S1 wakeup request because the transition state of the S1 interface of the target UE 300 being managed is the sleep state. Then, an S1 wakeup request for notifying that the sleep period has ended is transmitted from the message input / output unit 111.

  The MME 200 that has received the S1 wakeup request transmits an S1 wakeup response to reply to the eNB 100 that the wakeup request has been approved. The eNB 100 receives this S1 wakeup response (1-4). When the eNB 100 receives the S1 wakeup response from the MME 200, the eNB 100 changes the state of the S1 interface to the in-service state. That is, the message analysis processing unit 112 inputs the S1 wakeup response notified from the message input / output unit 111 to the state transition processing unit 121. The state transition processing unit 121 transitions the state of the managed S1 interface to the in-service state.

  Note that when the SCTP connection is reset and the state of the S1 interface transitions to the in-service state, the information held before transitioning to the sleep state is used as the context information.

  On the other hand, the SME wake-up request may be transmitted from the MME 200 upon detecting an incoming call addressed to the UE 300 where the MME 200 is in the sleep state (1-3c). In this case, the eNB 100 transmits an S1 wakeup response to the MME 200, and changes the state of the S1 interface to the in-service state. That is, the message analysis processing unit 112 inputs the S1 wakeup request notified from the message input / output unit 111 to the state transition processing unit 121. The state transition processing unit 121 transitions the state of the managed S1 interface of the target UE 300 to the in-service state, and instructs the message analysis processing unit 112 to transmit an S1 wakeup response. Then, an S1 wakeup response is transmitted from the message input / output unit 111.

  The above is the state transition of the S1 interface and the operation of the eNB 100 related thereto.

  Next, referring to FIG. 8, the state transition of the S1 interface and the operation of the MME 200 related thereto will be described.

  Also in the MME 200, as described with reference to FIG. 6, the start time / end time of the reservation process of each UE 300 is registered. And the S1 reservation request | requirement which notifies the start of the preservation | save process with respect to a certain UE300 is received from eNB100 (2-1).

  In the MME 200, the message analysis processing unit 212 inputs the S1 reservation request notified from the message input / output unit 211 to the state transition processing unit 221. The state transition processing unit 221 confirms that the state of the S1 interface of the target UE 300 being managed is the in-service state and that the time related to the reservation processing of the target UE 300 is registered in the mobility management unit 222.

  Then, the state transition processing unit 221 instructs the message analysis processing unit 212 to transmit an S1 preservation response indicating that this preservation processing has been approved. The S1 preservation response is transmitted from the message input / output unit 211. In addition, the state transition processing unit 221 transitions the state of the S1 interface to the sleep state. At this time, as described above, the context information is retained without being deleted.

  When the incoming call to the UE 300 is notified from the network side while the S1 interface is in the sleep state (2-2b), the MME 200 performs the process of resetting the SCTP connection and returning the S1 interface to the in-service state.

  In this case, the MME 200 resets the SCTP connection and transmits an S1 wakeup request to the eNB 100. That is, an incoming call detection event is input to the state transition processing unit 221. The state transition processing unit 221 instructs the message analysis processing unit 212 to reset the SCTP connection and transmit the S1 wakeup request because the transition state of the S1 interface of the target UE 300 being managed is the sleep state. Then, an S1 wakeup request is transmitted from the message input / output unit 211.

  The eNB 100 that has received the S1 wakeup request transmits an S1 wakeup response to reply to the MME 200 that the wakeup request has been approved. The MME 200 receives this S1 wakeup response (2-3). When the MME 200 receives the S1 wakeup response from the eNB 100, the MME 200 changes the state of the S1 interface to the in-service state. That is, the message analysis processing unit 212 inputs the S1 wakeup response notified from the message input / output unit 211 to the state transition processing unit 221. The state transition processing unit 221 changes the state of the S1 interface of the target UE 300 being managed to the in-service state.

  Note that when the SCTP connection is reset and the state of the S1 interface transitions to the in-service state, the information held before transitioning to the sleep state is used as the context information.

  Further, as described above, there is a case where the S1 wakeup request is received from the eNB 100 when the S1 interface is in the sleep state (2-2a). In this case, an S1 wakeup response is transmitted to the eNB 100, and the state of the S1 interface is changed to the in-service state. That is, the message analysis processing unit 212 inputs the S1 wakeup request notified from the message input / output unit 211 to the state transition processing unit 221. The state transition processing unit 221 changes the state of the S1 interface of the target UE 300 being managed to the in-service state, and instructs the message analysis processing unit 212 to transmit an S1 wakeup response. Then, an S1 wakeup response is transmitted from the message input / output unit 211.

  The above is the state transition of the S1 interface and the operation of the MME 200 related thereto.

  Next, the flow of the above-described preservation process will be described with reference to the sequence diagrams of FIGS.

  FIG. 9 is a sequence diagram illustrating a processing flow when the end time of the preservation process is detected during execution of the preservation process.

  First, when the S1 interface is in service, the timer management unit 123 of the eNB 100 starts processing by detecting the start time of a preservation process of a certain UE 300 (S301).

  The eNB 100 transmits an S1 preservation request notifying the start of the preservation process to the MME 200 (S302).

  The MME 200 confirms that the transition state of the S1 interface of the target UE 300 being managed is the in-service state and that the start time / end time of the preservation process related to the UE 300 is registered. Then, the MME 200 transmits an S1 reservation response for replying to the eNB 100 that the reservation request has been approved (S303).

  When the eNB 100 receives the S1 reservation response from the MME 200, the eNB 100 disconnects the SCTP connection (S304). At this time, both the eNB 100 and the MME 200 retain the context information regarding the target UE 300 without deleting it.

  The S1 interface enters a sleep state due to the disconnection of the SCTP connection.

  When the S1 interface is in the sleep state, the eNB 100 detects the preset end time of the reservation process using the timer information of the timer management unit 123 (S305).

  The eNB 100 resets the SCTP connection (S306). Then, an S1 wake-up request notifying that the sleep period has ended is transmitted to the MME 200 (S307).

  The MME 200 that has received the S1 wakeup request transmits an S1 wakeup response to reply to the eNB 100 that the wakeup request has been approved (S308).

  As a result, the S1 interface returns to the in-service state.

  As described above, when the SCTP connection is reset and the S1 interface is returned to the in-service state, the context information used before the transition to the sleep state is used.

  Further, the eNB 100 may add the information corresponding to the initial context setting request (Initial Context Setup Request) in the initial context setting procedure to the S1 wakeup request and transmit the information to the MME 200. With such a configuration, the S1 wakeup request and the initial context request can be transmitted simultaneously.

  FIG. 10 is a sequence diagram showing a process flow when a call from UE 300 is detected during execution of the preservation process.

  In other words, this is a process flow when a call from the UE 300 is detected before the end time of the reservation process is reached while the S1 interface enters the sleep period.

  The processing of S401 to S404 is the same as the processing of S301 to S304 in FIG.

  The eNB 100 detects that the UE 300 has made a call from the radio link connected to the UE 300 (S405). In this case, the timer management unit 123 of the eNB 100 is measuring the specified end time. Therefore, since no further timing is necessary, the timer management unit 123 stops the timer (S406).

  The subsequent processing is the same as the processing of S306 to S308 in FIG.

  That is, the eNB 100 resets the SCTP connection (S407). Then, an S1 wake-up request notifying that the sleep period has ended is transmitted to the MME 200 (S408).

  The MME 200 that has received the S1 wakeup request transmits an S1 wakeup response to reply to the eNB 100 that the wakeup request has been approved (S409).

  As a result, the S1 interface returns to the in-service state.

  FIG. 11 is a sequence diagram illustrating a process flow when an incoming call to UE 300 is detected during execution of the preservation process.

  That is, this is a process flow when the MME 200 detects an incoming call to the UE 300 before reaching the end time of the reservation process in a state where the S1 interface enters the sleep period.

  The processing of S501 to S504 is the same as the processing of S301 to S304 in FIG.

  When the S1 interface is in the sleep state, the MME 200 detects an incoming call to the UE 300 by a notification from the network side (S505).

  The MME 200 resets the SCTP connection (S506). Then, an S1 wakeup request notifying that the sleep period has ended is transmitted to the eNB 100 (S507).

  Note that the MME 200 may be configured such that the paging information for calling the UE 300 that is the call destination is added to the S1 wake-up request and transmitted to the eNB 100. With such a configuration, there is no need to send a separate paging message, which is efficient.

  The eNB 100 that has received the S1 wake-up request stops counting the timer of the corresponding UE 300 of the timer management unit 123 (S508). Then, an S1 wakeup response is transmitted to reply to the MME 200 that the wakeup request has been approved (S509).

  As a result, the S1 interface returns to the in-service state.

  The above is the description of the flow of the preservation process using the sequence diagram.

  Furthermore, the flow of processing for changing the setting of the start time / end time of the preservation processing in the above-described preservation processing will be described with reference to the sequence diagrams of FIGS.

  The start time / end time of the preservation process is set in the eNB 100 and the MME 200 by transmitting and receiving the S1 setup request and the S1 setup response in the S1 setup procedure described with reference to FIG. In order to change the set information, a configuration update message and a configuration update acknowledge message are used.

  FIG. 12 is a sequence diagram showing a flow of processing for changing the setting of the start time / end time of the preservation process from the MME 200 side.

  This process is applied when the MME 200 has a function of statistically processing the communication tendency of each UE 300 and determining the execution start / end time of the preservation process. This is used when the user's communication tendency changes greatly and the time zone when no communication is performed is changed.

  The MME 200 sets the start time / end time of the preservation process to be changed in the MME configuration update and transmits it to the eNB 100 (S601).

  The eNB 100 that has received the MME configuration update updates the reservation process start time / end time of the corresponding UE 300 to the notified time (S602). Further, the setting value of the corresponding timer of the timer management unit 123 is changed (S603).

  The eNB 100 that has performed the above process transmits an MME configuration update approval to the MME 200 (S604).

  The MME 200 that has received the MME configuration update approval updates the start time / end time of the preservation process managed by the MME 200 (S605).

  Next, a flow of processing for notifying update information from the eNB 100 will be described.

  FIG. 13 is a sequence diagram showing a flow of processing for changing the setting of the start time / end time of the preservation process from the eNB 100 side.

  This process is applied when the eNB 100 has a function of statistically processing the communication tendency of each UE 300 and determining the execution start / end time of the preservation process. This is used when the user's communication tendency changes greatly and the time zone when no communication is performed is changed.

  The eNB 100 sets the start time / end time of the preservation process to be changed in the eNB configuration update and transmits it to the MME 200 (S701).

  MME200 which received eNB configuration update updates the start time / end time of the preservation process of corresponding UE300 to the notified time (S702). Then, eNB configuration update approval is transmitted to the eNB 100 (S703).

  The eNB 100 that has received the eNB configuration update approval from the MME 200 updates the start time / end time of the preservation process managed by the eNB 100 (S704). Further, the eNB 100 changes the setting value of the corresponding timer of the timer management unit 123 (S705).

The above is the description of the process flow for changing the setting of the start time / end time of the preservation process. Also, a modification of the mobile communication system of the second embodiment described above will be described.

  In this modified example, when the S1 interface is in the sleep state, even if the UE 300 receives an incoming call from the network side, only the incoming call with a predetermined priority is accepted. With this configuration, it is possible to provide a service that only needs to handle an emergency incoming call during sleep.

  This is to include an allowable paging priority (Allowable Paging Priority) in addition to the setting information of the start time / end time of the preservation process in the S1 setup request used in the S1 setup procedure described with reference to FIG. What is necessary is just to comprise. Thereby, the MME 200 registers the allowable paging priority information in addition to the start time / end time of the preservation process for the target UE 300.

  And in the process which MME200 detects an incoming call during sleep demonstrated with reference to FIG. 11, it comprises so that the paging priority contained in the incoming call information notified from the network side may be identified. Then, the process for terminating the sleep state may be performed only for an incoming call with a priority higher than the allowable paging priority.

    As described above, the mobile communication system according to the present embodiment newly introduces a preservation process so that when the UE 300 is in a non-communication state, the SCTP connection of the S1 interface is disconnected to release resources. . Therefore, the mobile communication system of the present embodiment can effectively utilize the resources of the S1 interface between the eNB 100 and the MME 200.

  Then, the context information is retained when the connection is disconnected, and the context information is used when a predetermined event is detected and the connection is reset. For this reason, the mobile communication system of the present embodiment can reset the connection without delay even if the connection is disconnected, when resetting is necessary.

  Such a mobile communication system according to the present embodiment is used particularly in an environment where the bandwidth of the transmission section between the eNB 100 and the MME 200 is narrow or in an environment where the number of installed eNBs 100 is larger than the number of installed MMEs 200. Thus, a great effect is achieved.

  In addition, when executing this preservation process, necessary information is added as an additional parameter to the existing message of S1-AP, and four messages are newly defined as the S1 preservation message. Therefore, the above-described preservation process can be realized without changing the circuit so much.

DESCRIPTION OF SYMBOLS 1, 2 Mobile communication system 10 Radio base station 11, 21 Message transmission / reception means 12, 22 Preservation execution means 20 Mobility management station 30 Mobile terminal 100 eNB
111, 211 Message input / output unit 112, 212 Message analysis processing unit 121, 221 State transition processing unit 122 MME information management unit 123 Timer management unit 222 Mobility management unit

Claims (6)

A radio base station connected to a mobile terminal via a first link, a mobility management station connected to the radio base station via a second link and performing call connection control and standby position (mobility) management of the mobile terminal; With
Each of the radio base station and the mobility management station
When the communication by the mobile terminal is not performed for a predetermined time, the connection of the first protocol of the second link is disconnected, and a reservation process is executed for resetting when a predetermined event occurs. Reservation execution means;
Message transmission / reception means for transmitting / receiving information related to execution of the preservation process between the radio base station and the mobility management station using a message of the second protocol of the second link; ,
The preservation execution means holds context information including connection information and connection control information related to the mobile terminal when the connection is disconnected, and holds the context when the connection is reset. Using information ,
The second link is an LTE (Long Term Evolution) S1 interface, the first protocol is SCTP (Stream Control Transport Protocol), and the second protocol is S1-AP (S1 Application Protocol). Because
The preservation execution means includes a state transition processing unit that manages a state in which the SCTP connection is disconnected as a sleep state of the S1 interface and a state in which the SCTP connection is set as an in-service state of the S1 interface. ,
The message transmitting / receiving means adds and manages a message notifying the start of the preservation process and a message notifying the end of the preservation process in addition to the message of the S1-AP when executing the preservation process. Including a processing unit,
The message transmitting / receiving unit of the radio base station transmits the start time and end time of the reservation process for the mobile terminal as an additional parameter in an S1 setup request of the existing message of the S1-AP, Communicate to the mobility management station,
When the S1 interface is in the service state and the start time detection of the reservation process is input, the state transition processing unit of the radio base station sends the message transmission / reception means of the radio base station to the S1-AP The start of the preservation process is instructed to be transmitted to the mobility management station by transmitting the S1 reservation request of the message added to the message, and the S1 reservation response to the S1 reservation request is received from the mobility management station A mobile communication system , wherein the message transmission / reception means of the radio base station is instructed to disconnect the SCTP connection, and the S1 interface is changed to the sleep state . The state transition processing unit of the radio base station, at S1 interface the sleep state, there is an input of the calling detection from the input or the mobile terminal of the as predetermined event preservation processing end time detection And instructing the message transmission / reception means of the radio base station to reset the SCTP connection, and transmitting the S1 wake-up request for the message added to the S1-AP to terminate the preservation process. It instructs to transmit the movement from the mobility management station when there is a reception of the S1 wakeup response to step S1 wakeup request, according to claim 1, characterized in that shifting the step S1 interface to the service in state Communications system. The state transition processing unit of the mobility management station, at S1 interface the sleep state, when there is an input of an incoming call detection to the mobile terminal as the predetermined event, the message transmitting and receiving means of the mobility management station Instructing the wireless base station to reset the SCTP connection, instructing the wireless base station to transmit the completion of the preservation process by transmitting the S1 wakeup request of the message added to the S1-AP. If there is reception of the S1 wakeup response to step S1 wakeup request from the station, the mobile communication system according to claim 1, characterized in that shifting the step S1 interface to the service in state. A radio base station connected to a mobile terminal via a first link, a mobility management station connected to the radio base station via a second link and performing call connection control and standby position (mobility) management of the mobile terminal; A preserving process in which the connection of the first protocol of the second link is disconnected and reset when a predetermined event occurs when communication by the mobile terminal is not performed for a predetermined time Prescribe the execution of
Information related to execution of the preservation process is transmitted and received between the radio base station and the mobility management station using a message of the second protocol of the second link,
By executing the preservation process, when disconnecting the connection, the mobile terminal holds context information including connection information and connection control information related to the mobile terminal, and holds the context information when resetting the connection. Using context information ,
The second link is an LTE (Long Term Evolution) S1 interface, the first protocol is SCTP (Stream Control Transport Protocol), and the second protocol is S1-AP (S1 Application Protocol). Because
Managing the state in which the SCTP connection is disconnected as the sleep state of the S1 interface and the state in which the SCTP connection is set as an in-service state of the S1 interface;
In executing the preservation process, a message notifying the start of the preservation process and a message notifying the end of the preservation process are added to the S1-AP message and managed.
Including the start time and end time of the reservation processing for the mobile terminal as an additional parameter in the S1 setup request of the existing message of the S1-AP, and transmitting from the radio base station to the mobility management station;
When the S1 interface is in the service state and the start time of the preservation process is detected in the radio base station, an S1 reservation request for the message added to the S1-AP is transmitted to start the preservation process. To the mobility management station,
When the wireless base station receives an S1 reservation response to the S1 reservation request from the mobility management station, the SCTP connection is disconnected and the S1 interface is changed to the sleep state. Mobile communication method. At S1 interface the sleep state, when there is a detection of a call from the detection or the mobile terminal of the end time of the preservation process as the predetermined event at a radio base station, resetting the connection of the SCTP Then, an S1 wake-up request for the message added to the S1-AP is transmitted to notify the end of the preservation process to the mobility management station,
The mobile communication method according to claim 4 , wherein when the radio base station receives an S1 wake-up response to the S1 wake-up request from the mobility management station, the mobile base station transitions the S1 interface to the in-service state. At S1 interface the sleep state, when detecting an incoming call to the mobile terminal as the predetermined event at the mobility management station, reconfigure the connection of the SCTP, the message added to the S1-AP Transmitting an S1 wake-up request to inform the radio base station of the end of the preservation process;
The mobile communication method according to claim 4 , wherein when the mobility management station receives an S1 wakeup response to the S1 wakeup request from the radio base station, the S1 interface is changed to the in-service state.