JP2010226470A - Handover control system, mag, and handover control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a high-speed handover capable of totally reducing packet loss by avoiding congestion of a communication channel when the used band of the communication channel in which traffics are transferred is in a congestion state at the time of handover. <P>SOLUTION: The handover control system includes MAGs (mobile access gateways) 101, 102, an LMA (local mobility anchor) 100, and a PCRF (policy and charging rule function) resource control server 104. The system controls the handover of an MN (mobile user terminal) 103. The PCRF resource control server 104 monitors a traffic flow rate between a moving source MAG 101 and a moving destination MAG 102, limits a time for performing handover in FPMIP (fast proxy mobile IP protocol) for the moving source MAG 101 and the moving destination MAG 102 when the traffic flow rate exceeds a first threshold value, and gives an instruction for switching from the handover in the FPMIP to the handover in PMIP when the traffic flow rate exceeds a second threshold value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention comprises a plurality of MAGs (Mobile Access Gateways), an LMA (Local Mobility Anchor) that manages the MAGs, and a PCRF (Policy and Charging Rule Function) resource control server. The present invention relates to a handover control system, a MAG, and a handover control method for controlling a handover of a mobile user terminal performed with a destination MAG.

  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 control function (PCRF), which is a resource control server, in order to implement QoS / policy control.

  At present, in 3GPP, 3GPP2, and ITU-T, from P-CSCF (Proxy Call Session Control Function) corresponding to AF (Application Function) such as SIP (Session Initiation Protocol) server disclosed in Non-Patent Document 3 to PCRF. Policy control procedures for making network resource requests and the like 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, handover technology has been standardized around IETF as a technology for continuing user communication as much as possible when a mobile user terminal moves. However, at present, no specific method has been proposed on how to implement effective resource control in FPMIP, which is an IP mobility protocol, utilizing the policy control architecture of IMS.

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 (Local Mobility Anchor) 100, a PMAG (Previous Mobile Access Gateway) 101, an NMAG (Next Mobile Access Gateway) 102, and an MN (Mobile Node) 103. A tunnel T ₁ is established between the LMA 100 and the PMAG 101, and a tunnel T ₂ is established between the LMA 100 and the NMAG 102. Further, a tunnel T ₃ is established between the PMAG 101 and the NMAG 102 at the time of handover. 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 tunnel is established between the movement source MAG and the movement destination MAG. At this time, the traffic addressed to the MN is transferred via the tunnel between the MAGs until the destination MAG notifies the LMA of the movement of the MN and establishes the tunnel.

  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. In this method, the MN's movement destination MAG is notified of the movement of the MN, and a tunnel is established 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.

  In handover, it is desirable that packet loss be as small as possible. In FPMIP, after connecting to a destination MAG, a tunnel from LMA by PMIP is used from a tunnel between MAGs. In FPMIP, it is ideal in terms of reducing packet loss after confirming that there is no traffic flowing in the FPMIP tunnel from the source MAG, but in reality, the MAG is Since it is not known how long the user has been using the application, it is difficult to realize. The prior art does not define when the MAG will reject the FPMIP tunnel.

  Further, the conventional technology does not guarantee any traffic transfer in the tunnel established by the movement source MAG and the movement destination MAG. Therefore, when congestion occurs in the network path through which the tunnel between the movement source MAGs and the movement destination MAG passes, the MN may not be able to perform a seamless handover.

  The present invention has been made in view of such circumstances, and a handover control system, a MAG and a MAG that can reduce packet loss overall, avoid congestion of a communication path, and realize high-speed handover. An object is to provide a handover control method.

  (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 includes a plurality of MAGs (Mobile Access Gateways), an LMA (Local Mobility Anchor) that manages each MAG, and a PCRF (Policy and Charging Rule Function) resource control server. A handover control system for controlling a handover of a mobile user terminal performed between a movement source MAG and a movement destination MAG, wherein the PCRF resource control server has a traffic flow rate between the movement source MAG and the movement destination MAG. And an instruction to perform different handovers according to the traffic flow rate is given to the source MAG and destination MAG.

  In this way, the traffic flow between the movement source MAG and the movement destination MAG is monitored, and instructions for performing different handovers according to the traffic flow are given to the movement source MAG and the movement destination MAG. In addition to avoiding congestion on the communication path, it is possible to realize high-speed handover.

  (2) Also, in the handover control system of the present invention, the PCRF resource control server performs handover in FPMIP (Fast Proxy Mobile IP Protocol) according to the traffic flow rate for the source MAG and destination MAG. It is characterized by giving an instruction to switch between handovers in PMIP (Proxy Mobile IP Protocol).

  In this way, instructions for switching between handover in FPMIP and handover in PMIP are given to the source MAG and destination MAG according to the traffic flow rate, so that packet loss is reduced and communication path congestion is avoided. It is possible to realize a fast handover.

  (3) Further, in the handover control system of the present invention, the PCRF resource control server performs a handover in FPMIP when the traffic flow rate exceeds a first threshold for the movement source MAG and the movement destination MAG. It is characterized by limiting the time to be performed (the time during which traffic transfer is continued in a tunnel established between MAGs).

  As described above, when the traffic flow rate exceeds the first threshold for the source MAG and the destination MAG, the time for performing the handover in FPMIP (the time for continuing the traffic transfer in the tunnel established between the MAGs) However, the packet loss can be reduced as compared with the case where the handover is performed only by PMIP, although the packet loss is slightly generated as compared with the case where the handover is performed by FPMIP. Moreover, since the traffic flowing between the MAGs can be prevented from flowing for a long time by quickly rejecting the communication paths between the MAGs, it is possible to avoid further congestion of the communication paths between the MAGs. As a result, even when the network resources between MAGs are not sufficient, it is possible to provide an opportunity for high-speed handover by FPMIP to many mobile user terminals.

  (4) Further, in the handover control system of the present invention, the PCRF resource control server starts from the handover in FPMIP when the traffic flow rate exceeds the second threshold for the source MAG and destination MAG. It is characterized by giving an instruction to switch to handover in PMIP.

  In this way, when the traffic flow rate exceeds the second threshold value for the movement source MAG and the movement destination MAG, an instruction to switch from the FPMIP handover to the PMIP handover is given. It can be avoided.

  (5) The MAG of the present invention includes a plurality of MAGs (Mobile Access Gateways), an LMA (Local Mobility Anchor) that manages the MAGs, and a PCRF (Policy and Charging Rule Function) resource control server. MAG applied to a handover control system for controlling a handover of a mobile user terminal performed between a source MAG and a destination MAG, and in accordance with an instruction from the PCRF resource control server, FPMIP (Fast It is characterized by switching between handover in Proxy Mobile IP Protocol and handover in PMIP (Proxy Mobile IP Protocol).

  As described above, the FPMIP handover and the PMIP handover are switched according to the instruction from the PCRF resource control server, so that packet loss can be reduced, communication path congestion can be avoided, and high-speed handover can be realized. It becomes possible.

  (6) Further, the MAG of the present invention limits the time for performing a handover in FPMIP (the time for continuing traffic forwarding in a tunnel established between MAGs) according to an instruction from the PCRF resource control server. It is said.

  Thus, in accordance with an instruction from the PCRF resource control server, the time for performing the handover in FPMIP (the time for continuing the traffic transfer in the tunnel established between the MAGs) is limited, so that compared with the case of performing the handover by FPMIP Although some packet loss occurs, the packet loss can be reduced as compared with the case where handover is performed only with PMIP. Moreover, since the traffic flowing between the MAGs can be prevented from flowing for a long time by quickly rejecting the communication paths between the MAGs, it is possible to avoid further congestion of the communication paths between the MAGs. As a result, even when the network resources between MAGs are not sufficient, it is possible to provide an opportunity for high-speed handover by FPMIP to many mobile user terminals.

  (7) Further, the control method of the handover control system of the present invention includes a plurality of MAGs (Mobile Access Gateways), an LMA (Local Mobility Anchor) that manages the MAGs, and PCRF (Policy and Charging Rule Function) resource control. And a handover control method of a handover control system configured to control handover of a mobile user terminal performed between a source MAG and a destination MAG, wherein the source MAG in the PCRF resource control server Monitoring the traffic flow between the destination MAG and the destination MAG; determining whether the traffic flow exceeds a first threshold value or a second threshold value; When the threshold value of 1 is exceeded, FP for the source MAG and destination MAG A step of giving an instruction to limit a time for performing a handover in IP (Fast Proxy Mobile IP Protocol) (a time for continuing traffic forwarding in a tunnel established between MAGs); When the source MAG and destination MAG are instructed to switch from handover in FPMIP to handover in PMIP (Proxy Mobile IP Protocol), in the source MAG and destination MAG, In response to an instruction from the PCRF resource control server, a step of switching a handover in FPMIP to a handover in PMIP, and a time for performing a handover in FPMIP according to an instruction from the PCRF resource control server (between MAGs) And a step of limiting the time during which traffic forwarding is continued in the established tunnel).

  As described above, when the traffic flow rate exceeds the first threshold for the source MAG and the destination MAG, the time for performing the handover in FPMIP (the time for continuing the traffic transfer in the tunnel established between the MAGs) However, the packet loss can be reduced as compared with the case where the handover is performed only by PMIP, although the packet loss is slightly generated as compared with the case where the handover is performed by FPMIP. Moreover, since the traffic flowing between the MAGs can be prevented from flowing for a long time by quickly rejecting the communication paths between the MAGs, it is possible to avoid further congestion of the communication paths between the MAGs. As a result, even when the network resources between MAGs are not sufficient, it is possible to provide an opportunity for high-speed handover by FPMIP to many mobile user terminals. In addition, when the traffic flow rate exceeds the second threshold value for the movement source MAG and the movement destination MAG, an instruction to switch from the FPMIP handover to the PMIP handover is given, thereby avoiding communication path congestion between the MAGs. It becomes possible.

  According to the present invention, the traffic flow between the movement source MAG and the movement destination MAG is monitored, and instructions for performing different handovers according to the traffic flow are given to the movement source MAG and the movement destination MAG. Reduction and communication path congestion can be avoided, and high-speed handover can be realized.

It is a figure which shows the network structure assumed in this embodiment. It is a figure which shows schematic structure 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.
LMA (Local Mobility Anchor) 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 access network and an access point 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 the present embodiment, when there are not enough resources in the network on the communication path used by the MN for communication, IP Mobility is transferred to many mobile user terminals by utilizing 3GPP resource control procedures and controlling FPMIP. provide.

  FIG. 1 is a diagram showing a network configuration assumed in the present embodiment. The LMA 100 has established IP tunnels (communication paths) Ta to Te with the MAGs 101a to 101e. It is assumed that the address does not change even when the MN 103 moves to a radio access network under a certain MAG (IP mobility).

FIG. 2 is a diagram showing a schematic configuration of the handover control system according to the present embodiment. This handover control system includes an LMA (Local Mobility Anchor) 100, a PMAG (Previous Mobile Access Gateway) 101, an NMAG (Next Mobile Access Gateway) 102, an MN (Mobile Node) 103, and a PCRF (Resource Control Server) 104. And is composed of. A tunnel T ₁ is established between the LMA 100 and the PMAG 101, and a tunnel T ₂ is established between the LMA 100 and the NMAG 102. Further, a tunnel T ₃ is established between the PMAG 101 and the NMAG 102 at the time of handover.

  In this handover control system, when the MN 103 is handed over by FPMIP, the PCRF 104, which is an IMS policy control / acceptance control server, performs resource control according to the state of the communication path between the destination MAG 101 and the source MAG 102. . This supports realization of high-speed handover of the MN 103 in a network that accommodates various traffic such as the Internet and mobile services, such as a communication carrier.

The PCRF 104 monitors traffic between MAGs 101 and 102 adjacent on the network. Then, two thresholds are held for the communication paths between the MAGs, and acceptance control is performed when the MN 103 is handed over. In the first threshold, when the traffic flow of the communication path between the MAGs 101 and 102 does not exceed the physical band, but when the physical band is being compressed, the PCRF 104 receives the handover of the MN 103. accepting handover PFMIP, but notified to shorten the time to use the tunnel _{T 3} between the MAG101,102.

  In the second threshold, since the traffic flowing in the network between the MAGs is compressing the physical path of the communication path between the MAGs, the PFMIP handover cannot be accepted, and the PCRF 104 A notification is made to perform handover by PMIP.

  FIG. 4 is a sequence chart showing the operation of the handover control system according to the present embodiment. FIG. 4 shows Predictive handover. 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. That is, it notifies the handover of the MN by the L2 (radio access network) function. 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 “Accept (Reject)” to NMAG. At this time, the determination of “Handover change”, the availability of FPMIP movement, and the tunnel rejection between MAGs (timing to throw HI) are controlled.

  Next, NMAG transmits “Hack, MN ID” to PMAG. PMAG transmits “HI (F or U flag)” to NMAG, and NMAG transmits “HAck” to PMAG. Data is exchanged between PMAG and NMAG. Next, MN becomes attach from PMAG to attach and NMAG. Then, DL data is transmitted from NMAG to MN, and UL data is transmitted from MN to NMAG. This UL data is transmitted from NMAG to LMA via PMAG. Next, the PMAG sends “HI” to the NMAG to notify that the traffic transfer is completed, and the NMAG sends “HAck” to the PMAG. Next, NMAG establishes a tunnel with LMA, and switching to PMIP is performed.

  FIG. 5 is a sequence chart showing the operation of the handover control system according to the present embodiment. FIG. 5 shows a reactive handover. When the MN changes from PMAG to attach and NMAG, the NMAG transmits “MN ID, PMAG, NMAG” to the PCRF. The PCRF transmits “Accept (Reject)” to NMAG. At this time, the determination of “Handover change”, the availability of FPMIP movement, and the tunnel rejection between MAGs (timing to throw HI) are controlled.

  Next, NMAG transmits “HI, MN ID” to PMAG. PMAG transmits "MN ID, MN-HoA, MN IID, LMA" to NMAG. Data is exchanged between PMAG and NMAG. DL data from PMAG is transmitted to MN via NMAG. Further, UL data from the MN is transmitted to the PMAG via the NMAG, and is transmitted from the PMAG to the LMA. Next, “HI” is transmitted from PMAG to NMAG, and NMAG transmits “HAck” to PMAG. Next, NMAG establishes a tunnel with LMA, and switching to PMIP is performed.

  As described above, according to the present embodiment, when the traffic flow exceeds the first threshold, the PCRF 104 notifies the MAG to reject the tunnel established by FPMIP in a short time. . As a result, some packet loss occurs during the FPMIP handover, but a handover that does not cause a handover packet loss can be performed rather than a handover using only PMIP. Moreover, since the traffic flowing between the MAGs is prevented from flowing for a long time by quickly rejecting the tunnel between the MAGs, the communication path between the MAGs can be prevented from being further congested. As a result, the resource control when establishing a tunnel between MAGs by FPMIP is sufficient for network resources between MAGs by simply setting two-stage (multi-stage) thresholds rather than accept / reject resource control. Even if not, it is possible to provide high-speed handover by FPMIP to many MNs.

100 LMA
101 PMAG
101a-101e MAG
102 NMAG
103 MN
104 PCRF (resource control server)
Ta to Te tunnel (communication route)
T ₁ through T ₃ tunnel (communication path)

Claims (7)

It is composed of a plurality of MAGs (Mobile Access Gateways), LMAs (Local Mobility Anchors) that manage the MAGs, and PCRF (Policy and Charging Rule Function) resource control servers. A handover control system for controlling a handover of a mobile user terminal performed between
The PCRF resource control server monitors a traffic flow rate of a communication path between the movement source MAG and the movement destination MAG, and performs different handovers for the movement source MAG and the movement destination MAG according to the traffic flow rate. A handover control system characterized by giving an instruction.   The PCRF resource control server instructs the movement source MAG and the movement destination MAG to switch between handover in FPMIP (Fast Proxy Mobile IP Protocol) and handover in PMIP (Proxy Mobile IP Protocol) according to the traffic flow rate. The handover control system according to claim 1, wherein:   The PCRF resource control server restricts the time for which the traffic transfer is continued in the tunnel established between the MAGs when the traffic flow rate exceeds a first threshold for the source MAG and the destination MAG. The handover control system according to claim 2.   The PCRF resource control server gives an instruction to switch from a handover in FPMIP to a handover in PMIP when the traffic flow rate exceeds a second threshold to the source MAG and destination MAG. The handover control system according to claim 2. It is composed of a plurality of MAGs (Mobile Access Gateways), LMAs (Local Mobility Anchors) that manage the MAGs, and PCRF (Policy and Charging Rule Function) resource control servers. MAG applied to a handover control system for controlling a handover of a mobile user terminal performed between
A MAG that switches between execution of handover by FPMIP (Fast Proxy Mobile IP Protocol) and execution of handover by PMIP (Proxy Mobile IP Protocol) in accordance with an instruction from the PCRF resource control server.   6. The MAG according to claim 5, wherein the MAG is configured to limit a time during which traffic transfer is continued in a tunnel established between the MAGs according to an instruction from the PCRF resource control server. It is composed of a plurality of MAGs (Mobile Access Gateways), LMAs (Local Mobility Anchors) that manage the MAGs, and PCRF (Policy and Charging Rule Function) resource control servers. A handover control method of a handover control system for controlling a handover of a mobile user terminal performed between
In the PCRF resource control server,
Monitoring the traffic flow between the source MAG and the destination MAG;
Determining whether the traffic flow has exceeded a first threshold or a second threshold;
When the traffic flow rate exceeds a first threshold as a result of the determination, an instruction is given to the source MAG and destination MAG to limit the time for which traffic forwarding is continued in the tunnel established between the MAGs. Steps,
As a result of the determination, when the traffic flow rate exceeds a second threshold value, a step of giving an instruction to switch from the handover in FPMIP to the handover in PMIP (Proxy Mobile IP Protocol) to the source MAG and destination MAG When,
In the movement source MAG and the movement destination MAG,
Switching a handover in FPMIP to a handover in PMIP in response to an instruction from the PCRF resource control server;
And a step of limiting a time for performing a handover in FPMIP according to an instruction from the PCRF resource control server.

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