JP2012253680A - Offload handover method, radio base station and gateway device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an offload handover method, capable of handover while a radio terminal continues offload communication.SOLUTION: A handover source radio base station reports first address information, which is a radio terminal address in the self-station, to a handover target radio base station. A handover target radio base station reports second address information, which is a radio terminal address in the self-station, to the handover source radio base station. The handover source radio base station converts the transmission destination address of a packet which is destined to a radio terminal and received from a device in the Internet from the first address to the second address, and then transfers the packet to the handover destination radio base station through a public access network. The handover destination radio base station converts the transmission destination address of the received packet, from the second address to the first address, and transmits the packet to the radio terminal.

Description

  The present invention relates to an offload handover method in a mobile radio communication system that performs offload communication.

  In recent mobile communication systems, as shown in Non-Patent Document 1 below, a wireless terminal directly communicates with a server in the Internet via a small wireless base station, not via a mobile core network. Off-road communication is being considered. Moreover, in the following Patent Document 1, in a connection state via a mobile core network, a traffic amount between a wireless terminal and a server in the Internet is monitored, and when a predetermined condition is satisfied, the connection state does not pass through the core network A technique for switching to is disclosed.

JP 2010-226229 A

3GPP TS 22.20 V 9.4.0 (2010-03)

  However, according to the above conventional technique, the wireless terminal in the offload state communicates with a server on the Internet using the IP address for Internet connection acquired by the wireless base station. Therefore, when a wireless terminal moves and performs a handover to connect to another wireless base station, there is a problem that an IP address is changed and communication with a server on the Internet cannot be continued.

  The present invention has been made in view of the above, and an object of the present invention is to provide an offload handover method in which a wireless terminal performing offload communication can perform handover while continuing offload communication. .

  In order to solve the above-described problems and achieve the object, the present invention provides a wireless terminal connected to a device on the Internet via a wireless base station and not via a mobile core network but via a public access network. An offload handover method in a mobile communication system that performs offload communication, in which a handover source radio base station sends information on a first address that is an address for a radio terminal in its own station to a handover destination radio base station A first address notification step of notifying, and a second address notification in which the handover destination radio base station notifies the handover source radio base station of information of a second address which is a radio terminal address in the own station And a handover source wireless base station to the wireless terminal received from the device on the Internet. A handover source radio base station transfer step of converting a packet transmission destination address from the first address to the second address and transferring the packet to the handover destination radio base station via the public access network; A destination radio base station that converts a destination address of the received packet from the second address to the first address, and transmits the packet to the radio terminal. Thus, the handover is performed while the offload communication is continued.

  Advantageous Effects of Invention According to the present invention, there is an effect that a wireless terminal performing offload communication can perform handover while continuing offload communication.

FIG. 1 is a diagram showing a configuration example of a mobile communication system according to the first embodiment. FIG. 2 is a sequence diagram illustrating a handover operation according to the first embodiment. FIG. 3 is a diagram illustrating an address conversion table. FIG. 4 is a diagram showing an address conversion table. FIG. 5 is a diagram illustrating a configuration example of the mobile communication system according to the second embodiment. FIG. 6 is a sequence diagram illustrating a handover operation according to the second embodiment. FIG. 7 is a diagram illustrating a configuration example of a mobile communication system before handover according to the third embodiment. FIG. 8 is a sequence diagram illustrating a handover operation according to the third embodiment. FIG. 9 is a table showing correspondence between IP addresses and tunnels. FIG. 10 is a table showing the correspondence between the updated IP address and the tunnel. FIG. 11 is a diagram illustrating a configuration example of a mobile communication system after handover according to the third embodiment.

  Embodiments of an offload handover method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a mobile communication system according to the present embodiment. The mobile communication system includes a radio terminal (hereinafter referred to as UE) 1, a radio base station (hereinafter referred to as BTS) 2 and 3, a mobile communication core network 4, and a mobile communication core network 4. Mobile management device (hereinafter referred to as MME) 5, public access network 6, router 7 in public access network 6, gateway device (hereinafter referred to as GW) 8, Internet 9, And a server 10 on the Internet 9.

  The UE 1 is a terminal that can be connected to the BTSs 2 and 3 by radio. The BTSs 2 and 3 are connected to the UE 1 and relay communication with the mobile communication core network 4 or the public access network 6. The mobile communication core network 4 is a network that provides mobile communication. The MME 5 manages the movement of UE1 and communication calls. The router 7 routes packets in the public access network 6 and connects to the BTSs 2 and 3. The GW 8 connects the public access network 6 and the Internet 9. The server 10 is on the Internet 9 and provides various services. Here, the IP address of the server 10 is “IPS”.

  In FIG. 1, UE1 is connected to BTS2, uses a radio terminal (UE) address “IPU1” assigned to BTS2, and does not go through mobile communication core network 4, but BTS2 and public access network 6, off-road communication is performed with the server 10 on the Internet 9. As a method for obtaining the UE address, for example, there are various methods such as a method using DHCP (Dynamic Host Configuration Protocol) and a method of determining in advance, and the method is not limited to any one of the methods. The UE address “IPU1” is set as the first address.

  Next, an operation for performing handover from a state in which UE1 is performing offload communication will be described. FIG. 2 is a sequence diagram showing a handover operation in the mobile communication system according to the present embodiment.

  Here, in a state before the handover is performed, the transmission source address of the packet transmitted from the server 10 to the UE 1 is “IPS”, and the transmission destination address is “IPU 1”. The packet is routed to the UE 1 through the Internet 9, the GW 8, the router 7, and the BTS 2 by the transmission destination address “IPU 1”. Further, the source address of the packet transmitted from the UE 1 to the server 10 is “IPU1”, and the destination address is “IPS”. The packet is routed to the BTS 2, the router 7, and the GW 8 by the transmission destination address “IPS”, and further routed in the Internet 9 to arrive at the server 10. The UE 1 and the server 10 communicate with each other by specifying a communication partner based on the packet address.

  From this state, a case will be described in which handover is performed with BTS2 as the handover source (source radio base station) and BTS3 as the handover destination (target radio base station). First, the BTS 2 transmits a handover request to the MME 5 (step S1001). The MME 5 that has received the handover request transmits the handover request to the target BTS 3 (step S1002). Based on the received handover request, the BTS 3 performs a process (assignment process) for acquiring a UE address for the UE 1 and acquires the UE address “IPU 2” (step S1003). The UE address “IPU2” is set as the second address. Further, the BTS 3 transmits a handover request confirmation for approving the handover execution to the MME 5 (step S1004).

  The MME 5 transmits a handover command to the BTS 2 in order to notify the execution of the handover (Step S1005). The BTS 2 that has received the handover command transmits the handover command to the UE 1 (step S1006).

  The BTS 2 transmits a UE address notification to the MME 5 in order to notify the BTS 3 of the UE address “IPU1” used by the UE 1 (step S1007). MME5 which received UE address notification transmits UE address notification to BTS3 (step S1008). Further, the BTS 3 transmits a UE address notification to the MME 5 in order to notify the BTS 2 of the UE address “IPU2” acquired for the UE1 (step S1009). MME5 which received UE address notification transmits UE address notification to BTS2 (step S1010).

  On the other hand, UE1 that has received the handover command in step S1006 changes the connection destination to BTS3 and transmits a handover execution notification to BTS3 (step S1011). As a result, the BTS 3 recognizes that the UE 1 has performed handover and has connected to its own station.

  FIG. 3 is a diagram illustrating an address conversion table generated in the BTS 2 by handover. In BTS2, “IPU1” is converted to “IPU2”. FIG. 4 is a diagram showing an address conversion table generated in the BTS 3 by handover. In BTS3, "IPU2" is converted to "IPU1".

  After the handover shown in FIG. 2 is performed, when the server 10 transmits a packet to the UE 1 with the source address “IPS” and the destination address “IPU 1”, the BTS 2 before the handover is routed through the GW 8 and the router 7 in the Internet 9. The packet is transmitted to (step S1012). The BTS 2 converts the destination address “IPU1” to “IPU2” and transmits the packet to the router 7 (step S1013). The router 7 performs routing based on the transmission destination address “IPU2”, and transmits the packet to the BTS 3 (step S1014). Receiving this, the BTS 3 converts the destination address from “IPU2” to “IPU1” and transmits the packet to the UE1 (step S1015).

  On the other hand, when the UE 1 transmits a packet to the server 10 with the source address “IPU1” and the destination address “IPS”, the packet is routed to the BTS 3, the router 7, and the GW 8, and further routed through the Internet 9 to be sent to the server 10. It is transmitted (step S1016).

  As described above, in the present embodiment, when a radio terminal in offload communication performs a handover, the handover destination radio base station uses the radio terminal for the radio terminal used by itself to the handover source radio base station. The address is notified, and the handover source radio base station notifies the handover destination radio base station of the address for the radio terminal used by itself. Then, the handover source radio base station converts the transmission destination address to the radio terminal address in the handover destination radio base station for the packet having the handover source radio terminal address as the transmission destination address, and converts it into the public access network. On the other hand, for the packet having the wireless terminal address at the handover destination wireless base station as the transmission destination address, the handover destination wireless base station sets the transmission destination address to the wireless terminal address used before the handover. The data is converted and transmitted to the wireless terminal. As a result, the wireless terminal and the server on the Internet can use the same wireless terminal address before and after the handover, and the wireless terminal performs handover for moving the wireless base station while continuing offload communication. be able to.

Embodiment 2. FIG.
In Embodiment 1, the radio terminal address is converted between the handover source radio base station and the handover destination radio base station. In the present embodiment, when the radio terminal address in the handover source radio base station and the radio terminal address in the handover destination radio base station belong to the same subnetwork, the radio terminal continues to perform offload communication while continuing the offload communication. A method for performing handover for moving between base stations will be described. A different part from Embodiment 1 is demonstrated.

  FIG. 5 is a diagram illustrating a configuration example of the mobile communication system according to the present embodiment. Each configuration is the same as in the first embodiment (see FIG. 1), but here, BTSs 2 and 3 belong to the same subnetwork.

  Next, an operation for performing handover from a state in which UE1 is performing offload communication will be described. FIG. 6 is a sequence diagram showing a handover operation in the mobile communication system.

  The state before the handover is performed is the same as in the first embodiment. The operation from when the BTS 2 transmits a handover request to the MME 5 (step S1001) until the MME 5 transmits a UE address notification to the BTS 3 (step S1008) is the same as in the first embodiment.

  Next, the BTS 3 compares the UE address “IPU1” of the UE1 in the BTS2 before the handover indicated by the UE address notification received from the MME 5 with the UE address “IPU2” acquired from the router 7 by the local station. As a result of the comparison, it is detected that “IPU1” and “IPU2” belong to the same subnet (step S2001).

  Since the UE address acquired by BTS2 and the UE address acquired by BTS3 belong to the same subnet, when the server 10 transmits a packet, the packet is “IPU2” even if the destination address is “IPU1”. However, similarly, the public access network 6 is routed from the Internet 9 and arrives at the router 7 that accommodates the BTSs 2 and 3.

  The BTS 3 performs a process of changing the transmission destination of “IPU1” to the BTS 3 with respect to the router 7 (step S2002). As a method of changing the transmission destination, for example, when the connection between the public access network 6 and the BTSs 2 and 3 is Ethernet (registered trademark), the MAC corresponding to the UE address “IPU2” is transmitted by transmission of GARP (Gratuitous ARP). There is a method for causing the router 7 to learn the address, but the method is not limited to this.

  Thereafter, as in the first embodiment, UE1 that has received the handover command in step S1006 changes the connection destination to BTS3 and transmits a handover execution notification to BTS3 (step S1011). As a result, the BTS 3 recognizes that the UE 1 has performed handover and has connected to its own station.

  After the handover shown in FIG. 6 is performed, when the server 10 transmits a packet to the UE 1 with the transmission source address “IPS” and the transmission destination address “IPU 1”, the packet is routed from the Internet 9 through the public access network 6 to the router 7. To arrive. Since the transmission destination of “IPU1” is BTS3, the router 7 transmits this packet to BTS3, and BTS3 transmits this to UE1 (step S2003).

  On the other hand, when the UE 1 transmits a packet to the server 10 with the source address “IPU1” and the destination address “IPS”, the packet is routed to the BTS 3, the router 7, and the GW 8, and further routed through the Internet 9 to be sent to the server 10. It is transmitted (step S2004).

  As described above, in the present embodiment, when a radio terminal in off-road communication performs a handover, the radio base station that is the handover source uses the radio that was used by the local station to the radio base station that is the handover destination. Notify the terminal address. Then, the handover destination radio base station compares the address for the radio terminal acquired by the own station with the address for the radio terminal used by the radio base station of the handover source, and as a result of comparison, both addresses are in the same subnet. In the case of belonging, the router is caused to change the transmission destination of the packet addressed to the handover source wireless terminal address to the handover destination wireless base station. As a result, the wireless terminal and the server on the Internet can use the same wireless terminal address before and after the handover, and the handover for moving the wireless base station can be performed while the offload communication is continued. Further, the operation when transmitting a packet from the server to the wireless terminal after the handover can be simplified as compared with the first embodiment.

Embodiment 3 FIG.
In the first and second embodiments, routing in the public access network 6 is performed using the radio terminal address assigned to the UE 1. In this embodiment, when a tunnel is formed between the radio base stations 2 and 3 and the gateway device 8 and packets are transferred through the tunnel in the public access network 6, the radio base station continues with offload communication. A method for performing a handover for moving the mobile phone will be described. A different part from Embodiment 1, 2 is demonstrated.

  FIG. 7 is a diagram illustrating a configuration example of a mobile communication system before handover according to the present embodiment. Here, there is no router 7 in the public access network 6, and the BTS 2 and GW 8 have a function of configuring a tunnel 101 for packet transmission between the public access networks 6. As a technique for configuring a tunnel, there are various techniques such as a PPP (Point to Point Protocol) and an IPsec (Security Architecture for Internet Protocol) tunnel. In FIG. 7, a tunnel 101 is a tunnel set between the BTS 2 and the GW 8. Communication data between the server 10 and the UE 1 is routed in the Internet 9 with an address assigned to the server 10 or the UE 1, and is transferred on the tunnel 101 in the public access network 6.

  Next, an operation for performing handover from a state in which UE1 is performing offload communication will be described. FIG. 8 is a sequence diagram showing a handover operation in the mobile communication system according to the present embodiment.

  In a state before the handover is performed, the transmission source address of the packet transmitted from the server 10 to the UE 1 is “IPS”, and the transmission destination address is “IPU 1”. The packet is routed through the Internet 9 by the transmission destination address “IPU1” and arrives at the GW 8. FIG. 9 is a table showing correspondence between IP addresses held by the GW 8 and tunnels. Based on this table, the GW 8 transmits the packet having the transmission destination address “IPU1” to the tunnel 101, and transfers the packet within the public access network 6 to the BTS 2 through the tunnel 101. BTS2 transmits a packet of destination address “IPU1” to UE1. Further, the source address of the packet transmitted from the UE 1 to the server 10 is “IPU1”, and the destination address is “IPS”. The BTS 2 also holds a table similar to the table shown in FIG. 9, and the BTS 2 transmits a packet whose transmission source address is “IPU 1” using the tunnel 101. The packet is transmitted through the public access network 6 through the tunnel 101, arrives at the GW 8, is routed through the Internet 9 by the destination address “IPS”, and arrives at the server 10.

  From this state, a case will be described in which handover is performed with BTS2 as the source radio base station and BTS3 as the target radio base station. First, the BTS 2 transmits a handover request to the MME 5 (step S3001). The MME 5 that has received the handover request transmits the handover request to the BTS 3 that is the target radio base station (step S3002). The BTS 3 performs processing for generating a tunnel for the UE 1 with the GW 8 (step S3003).

  After generating the tunnel, the BTS 3 transmits a handover request confirmation for approving the handover to the MME 5 (step S3004). The MME 5 transmits a handover command to the BTS 2 in order to notify the execution of the handover (step S3005). The BTS 2 that has received the handover command transmits a handover command to the UE 1 (step S3006). The BTS 2 transmits a UE address notification to the MME 5 in order to notify the BTS 3 of the UE address “IPU1” used by the UE 1 (step S3007). MME5 which received UE address notification transmits UE address notification to BTS3 (step S3008). The BTS 3 that has received the UE address notification transmits a transfer destination change request to the GW 8 in order to change the transmission destination of the transmission destination address “IPU1” in the GW 8 from the tunnel 101 to the tunnel 102 (step S3009). When the GW 8 receives the transfer destination change request, the GW 8 updates a table that holds the correspondence between the UE address and the tunnel (step S3010). FIG. 10 is a table showing correspondence between updated IP addresses and tunnels held by the GW 8. The tunnel 102 is associated with the address “IPU1”.

  On the other hand, UE1 that has received the handover command in step S3006 changes the connection destination to BTS3, and transmits a handover execution notification to BTS3 (step S3011). Recognize that you are connected.

  FIG. 11 is a diagram illustrating a configuration example of a mobile communication system after handover. Communication data between the UE 1 and the server 10 is transferred on the tunnel 102 set between the BTS 3 and the GW 8.

  After the handover shown in FIG. 10 is performed, when the server 10 transmits a packet to the UE 1 with the transmission source address “IPS” and the transmission destination address “IPU 1”, the packet arrives from the Internet 9 to the GW 8. The GW 8 transmits the packet to the BTS 3 through the tunnel 102, and the BTS 3 transmits this to the UE 1 (step S3012).

  On the other hand, when the UE 1 transmits a packet to the server 10 with the source address “IPU1” and the destination address “IPS”, the BTS 3 is transferred to the GW 8 through the tunnel 102 and further routed through the Internet 9 to be sent to the server 10. It is transmitted (step S3013).

  As described above, in the present embodiment, when a radio terminal in offload communication performs handover, the handover source radio base station notifies the handover destination radio base station of the radio terminal address, The handover destination radio base station notifies the gateway device located at the boundary between the public access network and the Internet of the tunnel corresponding to the radio terminal address, and the gateway device uses the radio terminal address. It was decided to change the tunnel. As a result, even when a tunnel is configured for communication, the wireless terminal and the server on the Internet can use the same wireless terminal address before handover and after handover. The handover for moving the radio base station can be performed while continuing.

1 Radio terminal (UE)
2, 3 Radio base station (BTS)
4 Mobile communication core network 5 Mobility management device (MME)
6 Public access network 7 Router 8 Gateway device (GW)
9 Internet 10 Server 101, 102 Tunnel

Claims (7)

An offload handover method in a mobile communication system in which a wireless terminal performs offload communication with a device on the Internet via a public access network without passing through a mobile core network via a wireless base station,
A first address notification step in which the handover source radio base station notifies the handover destination radio base station of information of a first address that is an address for a radio terminal in the own station;
A second address notification step in which the handover destination radio base station notifies the handover source radio base station of information of a second address that is an address for the radio terminal in the own station;
The handover source radio base station converts the transmission destination address of the packet addressed to the radio terminal received from the device on the Internet from the first address to the second address, and transmits the packet via the public access network. A handover source radio base station transfer step of transferring to the handover destination radio base station;
A handover destination radio base station transmitting a handover destination radio base station that converts a transmission destination address of the received packet from the second address to the first address and transmitting the packet to the radio terminal;
The offload handover method is characterized in that the handover is performed while continuing the offload communication. An offload handover method in a mobile communication system in which a wireless terminal performs offload communication with a device on the Internet via a public access network without passing through a mobile core network via a wireless base station,
An address notification step in which the handover source radio base station notifies the handover destination radio base station of the information of the first address that is the address for the radio terminal in the local station;
An address comparison step in which the handover destination radio base station compares the received first address with a second address that is a radio terminal address in the own station;
As a result of the comparison, when the handover destination radio base station detects that the handover source radio base station and its own station belong to the same subnet, the destination address is the first address for the public access network. A transmission destination changing step for changing a transmission destination of a packet addressed to a certain wireless terminal from the handover source wireless base station to the own station;
A handover destination radio base station transmitting step, wherein the handover destination radio base station sends a packet addressed to the radio terminal whose destination address received from the device on the Internet is a first address;
The offload handover method is characterized in that the handover is performed while continuing the offload communication. The radio terminal uses the tunnel set up between the radio base station and the gateway device that connects the public access network and the Internet via the radio base station, without going through the mobile core network, and the public access An offload handover method in a mobile communication system that performs packet transfer in a network and performs offload communication with a device on the Internet via the gateway device,
An address notification in which a handover source radio base station that sets up a first tunnel with the gateway device and transfers packets notifies the handover destination radio base station of information on the address for the radio terminal in the own station Steps,
For a second tunnel set up between the handover destination radio base station and the gateway device, a packet whose destination is the radio terminal address received from the device on the Internet to the gateway device A tunnel change step of changing the transfer destination of the first tunnel from the first tunnel;
A packet transfer step in which a handover destination radio base station transfers, using the second tunnel, a destination of a packet received from the radio terminal and addressed to the device on the Internet;
The offload handover method is characterized in that the handover is performed while continuing the offload communication. The wireless base station is an unrelated base station in a mobile communication system that performs offload communication with a device on the Internet through a public access network without going through a mobile core network via a wireless base station,
For the handover source radio base station,
The handover destination radio base station is notified of the information of the first address which is the radio terminal address in the local station, and the destination address of the packet addressed to the radio terminal received from the device on the Internet is handed over Converting to a second address that is a radio terminal address in the handover destination radio base station notified from the destination radio base station, and transferring the packet to the handover destination radio base station via the public access network;
In the case of a handover destination radio base station,
The handover source radio base station is notified of the second address information, and the destination address of a packet received from the handover source radio base station via the public access network is set to the second address. To the first address and transmit to the wireless terminal,
Thus, a radio base station that performs handover while continuing off-road communication. The radio base station in the mobile communication system in which the radio terminal performs offload communication with a device on the Internet via the public access network without going through the mobile core network via the radio base station,
For the handover source radio base station,
Notifying the handover destination radio base station of the information of the first address that is the address for the radio terminal in the own station,
In the case of a handover destination radio base station,
When the received first address is compared with the second address that is the address for the wireless terminal in the local station, and as a result of comparison, when it is detected that the handover source wireless base station and the local station belong to the same subnet The destination address of the packet destined for the wireless terminal whose destination address is the first address is changed from the handover source radio base station to the local station and received from the device on the Internet. A packet addressed to the wireless terminal whose destination address is the first address is transmitted to the wireless terminal;
Thus, a radio base station that performs handover while continuing off-road communication. The radio terminal uses the tunnel set up between the radio base station and the gateway device that connects the public access network and the Internet via the radio base station, without going through the mobile core network, and the public access The wireless base station in a mobile communication system that performs packet transfer in a network and performs offload communication with a device on the Internet via the gateway device,
For the handover source radio base station,
Before handover, the first tunnel is set up with the gateway device to transfer the packet, and the handover destination radio base station is notified of the address information for the radio terminal in its own station,
In the case of a handover destination radio base station,
For the second tunnel set up with the gateway device, a forwarding destination in the case of a packet with the address for the wireless terminal received from the device on the Internet as the destination is sent to the gateway device. The first tunnel is changed to the second tunnel, and the transmission destination of the packet addressed to the device on the Internet received from the wireless terminal is transferred using the second tunnel.
Thus, a radio base station that performs handover while continuing off-road communication. The radio terminal uses the tunnel set up between the radio base station and the gateway device that connects the public access network and the Internet via the radio base station, without going through the mobile core network, and the public access The gateway device in a mobile communication system that performs packet transfer in a network and performs offload communication with a device on the Internet via the gateway device,
A tunnel is newly set up with the handover destination radio base station at the time of handover, and in accordance with a request from the handover destination radio base station, a packet transfer destination having a radio terminal address in the handover source radio base station as a transmission destination is set. , Change to the tunnel set up with the handover destination radio base station,
A gateway device characterized by that.

Images