JP5191935B2 - Handover control system, access router, and handover control method - Google Patents

Description

  The present invention relates to a handover control system, an access router, and a handover control method for controlling a handover method of a mobile user terminal performed between a plurality of access networks.

  In recent years, many fixed-line and mobile communication providers that provide public circuit switching services have been using the Internet to integrate fixed- and mobile networks based on the NGN (Next Generation Network) architecture, which is being standardized as a next-generation network. We are moving to an IP-based network that can be easily integrated with services. IMS (IP Multimedia Subsystem), which is the core technology of NGN, uses a policy and charging rules function (PCRF) serving as a resource control server in order to implement QoS / policy control.

  Currently, in 3GPP, 3GPP2, and ITU-T, network resources are provided from the P-CSCF (Proxy Call Session Control Function) corresponding to AF (Application Function) such as SIP (Session Initiation Protocol) server (Non-patent Document 3) to the PCRF. Policy control procedures for making requests are specified. Furthermore, a procedure for opening / closing a port and setting a policy for controlling media traffic from a user is defined from the PCRF to an AGW (Access Gateway) which is a transport edge router.

  On the other hand, as a technique for continuing user communication as much as possible when a user terminal moves, a handover technique has been standardized centering on IETF. However, at present, a specific method for implementing effective resource control in FPMIP (Fast Proxy MIP), which is an IP mobility protocol, utilizing the policy control architecture of IMS has not been proposed.

IETF draft-ietf-mipshop-pfmipv6-01.txt 3GPP TS 23.203 V8.4.0 “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Policy and charging control architecture (Release 8)” IETF RFC3261 “Session Initiation Protocol” IETF RFC5213 “Proxy Mobile IP”

  However, in the conventional technology, in IMS, when a user starts using an application using a resource control server called PCRF, a method for assigning a QoS class to traffic of the application based on a call made by SIP is proposed. (Non-Patent Document 3).

  On the other hand, FPMIP is defined as a fast handover technique. FIG. 3 is a diagram showing an outline of FPMIP. The FPMIP includes an LMA (Location Management Agent) 100, a PMAG (Previous Mobile Access Gateway) 101, an NMAG (Next Mobile Access Gateway) 102, and an MN (Mobile Node) 103. This FPMIP extends the PMIP protocol (Non-Patent Document 4).

  In PMIP (Proxy MIP), the MN does not need to have a function for performing a handover, and a MAG (Mobile Access Gateway) connected to the MN manages the movement of the MN. When the MN connects to the MAG, the MAG notifies the LMA of the information, and establishes a tunnel between the LMA and the MAG. When the MN moves to another MAG, the destination MAG notifies the LMA that the MN has newly connected and establishes a tunnel. Thereafter, the LMA rejects the tunnel with the source MAG.

  On the other hand, in FPMIP, when the MN moves, a traffic transfer tunnel is established between the MAG at the movement source and the MAG at the movement destination. Thereafter, the destination MAG notifies the LMA of the movement of the MN, and forwards the traffic addressed to the MN via the tunnel between the MAGs until a new traffic transfer tunnel is established with the LMA.

  4 and 5 are diagrams showing a handover sequence in FPMIP. FIG. 4 shows a Predictive handover sequence. The Predictive handover shown in FIG. 4 is a handover based on the premise that the radio access network can detect the movement of the MN. This is a method of notifying the MN's movement destination MAG of the movement of the MN and establishing a traffic transfer tunnel between the movement source MAG and the movement destination MAG before the MN connects to the movement destination MAG in advance.

  FIG. 5 illustrates a reactive handover sequence. The reactive handover shown in FIG. 5 does not assume that the radio access network detects the movement of the MN, but establishes a tunnel between the movement source MAG and the movement destination MAG after the MN connects to the movement destination MAG. The tunnel between the MAGs rejects the tunnel from the source MAG, and the MN then transmits and receives traffic using the tunnel formed by PMIP between the LMA and the destination MAG.

  When executing a handover, in a situation where the use band of the source radio access network is congested, it is desirable to cause the MN to execute a handover at high speed and to hand over many MNs to another radio access network. In the Predictive handover, the process of establishing a tunnel between the MAGs that forwards the traffic during the handover by FPMIP is executed before the MN moves. Therefore, compared with the case where the Reactive handover is executed. There is a problem that it takes time for the MN to leave the source access network. When the Predictive type handover is executed, the MN can execute the handover with little packet loss, but the time required for being located in the source radio access network tends to be long.

  The present invention has been made in view of such circumstances, and by quickly switching the handover method of the MN in accordance with the congestion status of the access network of the movement source, the MN is quickly detached from the access network of the movement source, An object of the present invention is to provide a handover control system, an access router, and a handover control method capable of improving the congestion situation of an access network.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the handover control system of the present invention is a handover control system that controls handover of a mobile user terminal performed between a plurality of access networks, and a plurality of access routers that manage the access network and a mobile user terminal are located And a control server that monitors the bandwidth usage of the source access network that performs the notification that the Predictive handover is performed from the mobile user terminal when a predetermined condition is satisfied. When there is, an instruction to perform a reactive handover is given to the access router that manages the access network of the movement source.

  As described above, when a predetermined condition is satisfied, when there is a notification from the mobile user terminal that the Predictive handover is performed, the access router that manages the access network of the movement source Since an instruction to perform the reactive handover is given, the mobile user terminal can perform the handover without waiting for a tunnel between access routers to be established. As a result, the mobile user terminal can be quickly detached from the source access network.

  (2) Further, in the handover control system of the present invention, the control server may provide access routers that manage the access network of the movement source when congestion of a certain value or more occurs in a use band of the movement source access network Thus, an instruction to perform a reactive handover is given.

  In this way, when congestion of a certain value or more occurs in the source access network, the access router that manages the source access network is instructed to perform a reactive handover, and is congested. A mobile user terminal can be quickly handed over from the current access network, and the congestion status of the access network can be alleviated.

  (3) The access router of the present invention is an access router applied to a handover control system for controlling a handover of a mobile user terminal performed between a plurality of access networks, and is a source of movement of the mobile user terminal According to the notification from the control server that monitors the bandwidth usage of the access network, the mobile user terminal is made to perform the handover by switching from the Predictive handover to the Reactive handover.

  As described above, when a predetermined condition is satisfied, when there is a notification from the mobile user terminal that the Predictive handover is performed, the access router that manages the access network of the movement source Since an instruction to perform the reactive handover is given, the mobile user terminal can perform the handover without waiting for a tunnel between access routers to be established. As a result, the mobile user terminal can be quickly detached from the source access network.

  (4) Further, the handover control method of the present invention is a handover control method for controlling handover of a mobile user terminal performed between a plurality of access networks, and the source access in which the mobile user terminal is located in the control server. A step of monitoring the bandwidth usage of the network, and when congestion of a certain value or more occurs in the bandwidth usage of the access network of the movement source as a result of the monitoring, a Predictive handover is performed from the mobile user terminal In response to the notification from the control server in the source access router, the step of giving an instruction to perform the reactive handover to the access router that manages the source access network, Predictive method Switch to handover Reactive systems from Dooba is characterized in that it comprises a step of carrying out the handover to the mobile user terminal, at least.

  In this way, when congestion occurs in the access network of the movement source, when the mobile user terminal is notified that the Predictive handover is performed, the access router that manages the access network of the movement source Since an instruction to perform a reactive handover is given, the mobile user terminal can perform the handover without waiting for the establishment of a tunnel between access routers. As a result, the mobile user terminal can be quickly detached from the source access network. As a result, the congestion status of the access network can be alleviated.

  According to the present invention, when a predetermined condition is satisfied, when there is a notification from the mobile user terminal that a Predictive handover is performed, the access router that manages the access network of the movement source Thus, the mobile user terminal can execute the handover without waiting for the establishment of the tunnel between the access routers. As a result, the mobile user terminal can be quickly detached from the source access network.

It is a figure which shows schematic structure of the handover control system which concerns on this embodiment. It is a sequence chart which shows operation | movement of the handover control system which concerns on this embodiment. It is a figure which shows the outline | summary of FPMIP. It is a figure which shows the sequence of the handover in FPMIP. It is a figure which shows the sequence of the handover in FPMIP.

[Definition of terms]
MN (Mobile Node) means a mobile user terminal.
The MN-ID (MN Identifier) is an ID that uniquely indicates the MN.
The MN-IID (MN Interface Identifier) is an ID indicating the IF of the MN.
CN (Corresponding Node) is a communication partner of the mobile user terminal.
MAG (Mobile Access Gateway) is an access router.
PMAG / NMAG (Previous MAG / Next MAG) is a source MAG and a destination MAG.
An LMA (Location Management Agent) is an anchor for mobility management.
PCRF (Policy and Changing Rule Function) is a policy control server.
AN / AP (Access Network / Access Point) is an AN / AP to which a user attaches.
P-AN / N-AN (Previous AN / Next AN) is a source access network and a destination access network.

  In 3GPP, a procedure for performing resource control and providing QoS for communication of a mobile user terminal (Mobile Node: hereinafter referred to as “MN”) is standardized (Non-patent Document 1). On the other hand, Fast Proxy Mobile IP protocol (hereinafter referred to as “FPMIP”) has been studied as a protocol for realizing IP Mobility at high speed (Non-patent Document 2). In FPMIP, a function of two layers below the IP layer is utilized to notify the destination network that the MN is handed over before the handover of the MN and the MN connects to the destination network. There is a Reactive method in which the handover process is advanced after that. The Predictive method is generally considered to be used by telecommunications carriers because it can implement a generally faster handover than the Reactive method.

  In the present embodiment, when the MN performs a handover, an inquiry is made to the PCRF (resource control server), and the FPMIP controls whether the handover is performed by the Predictive method or the Reactive method according to the status of the source access network.

  FIG. 1 is a diagram showing a schematic configuration of a handover control system according to the present embodiment. The handover control system includes an LMA (Location Management Agent) 100, a PMAG (Previous Mobile Access Gateway) 101, an NMAG (Next Mobile Access Gateway) 102, an MN (Mobile Node) 103, a PCRF (Resource Control Server) 104, , Is composed of.

  As shown in FIG. 1, MAGs (PMAG 101, NMAG 102) are distributed and arranged on a core network that serves as an edge router when the MN 103 connects to the core network. The PCRF (resource control server) 104 performs resource control when the MN 103 connects to the MAG (PMAG 101). The PCRF (resource control server) 104 measures the utilization rate of the radio access network under each MAG (PMAG 101, NMAG 102).

  The PCRF (resource control server) 104 determines whether the handover should be switched from the Predictive method to the Reactive method when the MN 103 performs handover, and notifies the MAG (PMAG 101).

  In this handover control system, when the MN 103 performs a Predictive handover by FPMIP, the PCRF (resource control server) 104, which is the policy control / acceptance control server of the IMS, uses the resource of the source radio access network (P-AN). To monitor. In a situation where the source wireless access network (P-AN) is congested, the MN is quickly connected to the destination access network (N-AN).

  Specifically, when the MN 103 notifies the PCRF (resource control server) 104 that the Predictive handover has been performed, the PCRF (resource control server) 104 performs the reactive handover to the PMAG 101. Notice.

  FIG. 2 is a sequence chart showing the operation of the handover control system according to the present embodiment. The MN transmits “MN ID, New AP ID” as a report to the P-AN. The P-AN transmits “MN ID, New AP ID” as HO Initiate to PMAG. The PMAG transmits “MN ID, MN-HoA, MN IID, LMA Address” to the NMAG. NMAG transmits “MN ID, PMAG, NMAG” to the PCRF. The PCRF transmits “Handover change” to the NMAG. NMAG transmits “MN ID, Handover change” to PMAG. As a result, the handover is switched from the Predictive method to the Reactive method. Therefore, “HI (F or U flag), HAck” is not exchanged between PMAG and NMAG, and data transmission / reception is not performed (tunnel is not established).

  PMAG performs a Detach on MN, and MN is connected from PMAG to NMAG. When the MN and NMAG are connected, the NMAG transmits “MN ID, PMAG, NMAG” to the PCRF. The PCRF transmits “Accept (Reject)” to the NMAG. NMAG transmits “HI (MN ID), HAck” to PMAG. PMAG transmits "MN ID, MN-HoA, MN IID, LMA" to NMAG. Data is exchanged between PMAG and NMAG. Thereby, the Reactive method is executed.

  As described above, according to the present embodiment, the MN handover method is switched from the Predictive method to the Reactive method according to the congestion status of the source access network. As a result, the MN can perform handover without waiting for the establishment of a tunnel between MAGs, and can quickly leave the source access network. By switching the handover, the MN can be quickly handed over from the access network in a congested state, and the congestion state of the access network can be alleviated.

  Certainly, performing reactive handover increases the packet loss at the time of handover, but by quickly executing MN handover, the number of MNs using a congested radio access network is rapidly reduced. be able to. In general, the difference in handover time between the Predictive method and the Reactive method is about several seconds, and the influence on the MN is small. As a result, it is possible to prevent a phenomenon in which the MN that continues to use the radio access network cannot transmit and receive traffic due to congestion of the radio access network.

100 LMA
101 PMAG
102 NMAG
103 MN
104 PCRF (resource control server)

Claims (3)

A handover control system for controlling a handover of a mobile user terminal performed between a plurality of access networks,
Multiple access routers managing the access network;
A control server that monitors the bandwidth usage of the source access network in which the mobile user terminal is located,
When there is congestion of a certain value or more in the bandwidth usage of the access network of the movement source , the control server, when notified from the mobile user terminal that the Predictive handover is performed, A handover control system characterized by giving an instruction to perform a reactive handover to an access router that manages an access network. An access router applied to a handover control system for controlling a handover of a mobile user terminal performed between a plurality of access networks,
When the control server that monitors the bandwidth usage of the source access network in which the mobile user terminal is located receives a notification that congestion of a certain value or more has occurred in the bandwidth usage, the reactive scheme from the handover of the predictive scheme An access router characterized in that the mobile user terminal is handed over by switching to the handover. A handover control method for controlling handover of a mobile user terminal performed between a plurality of access networks,
Monitoring the bandwidth usage of the source access network where the mobile user terminal is located in the control server;
As a result of the monitoring, when congestion exceeding a certain value occurs in the bandwidth usage of the access network of the movement source, when the mobile user terminal is notified that the Predictive handover is performed, Providing an instruction to perform a reactive handover to an access router managing an access network;
In the source access router, the handover control includes at least a step of switching from the Predictive handover to the Reactive handover in response to the notification from the control server, and causing the mobile user terminal to perform the handover. Method.

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