Mobile communication method, radio base station, and upper level node

MOBILE COMMUNICATION METHOD, RADIO BASE STATION AND TOP NODE

Technical Field

The present invention relates to a mobile communication method for handovering a mobile station from a handover source radio base station to a handover target radio base station in a mobile communication system including multiple base stations radio and a top node of multiple radio base stations.

In addition, the present invention relates to a radio base station and an upper node used in the above mobile communication method.

Background of the Technique

In an IMT-2000 (International Mobile Telecommunication-2000) system, as shown in figure 1, an Iu interface is defined between a RAN (Radio Access Network) node (for example, RNC: Radio Network Controller - Radio Network Controller) and a central node (for example, SGSN; Serving GPRS Service Node - GPRS Server Operation Node) and a GTP tunnel (GPRS Tunneling Protocol) used for data transmission in a user plane (U-plane) is established in the UI interface.

In the IMT-2000 system above, when a mobile station performs a handover via RNCs which are under the control of the same SGSN, that is, when the mobile system performs “SRSK relocation”, the SGSN transmits a “Relocation Request message ”Using RANAP (Radio Access Network Application Part - Part of the Radio Access Network application) and the final GTP tunnel ID on the SGSN side is reset.

That is, an SGK informs RNC # 2 of a final GTP tunnel ID on the Node B side using the “Relocation Request message” and, thus, a GTP tunnel # 2 is established between the SGSN and an RNC # 2 handover target.

Petition 870190121452, of 11/22/2019, p. 14/18

Non-Patent Document 1: 3GPP TS25.413.

Disclosure of the Invention

In a next generation mobile communication system (for example, LTE: Long Term Evolution) after XMT-2000 systems, an SI interface corresponding to an lu interface is defined. Also, at the SI interface, a GTP tunnel is configured between a RAN node (for example, an eNB radio base station) and a central node (for example, Port SAE (System Architecture Evolution - Evolution of System Architecture).

In the mobile communication system above, in handover, an SAE Access Terminal, corresponding to an SAE Access Terminal having been established between an eNB handover source radio base station and the central node SAE Port, needs to be configured between a station eNB handover target radio base and the central node SAE Port.

Usually, the central node SAE Port starts the establishment above the SAE Access Terminal.

In the LTE system, however, handover is performed as follows. Specifically, as shown in figure 2, an eNB2 handover target radio base station transmits a Complete Handover message in step S2007. Then, in step S2008, a central node SAE Port performs processing to reallocate a TE (End of Tunnel) ID on the side of the central node in the GTP tunnel to be configured between the central node and the target radio base station of eNB handover₂. Consequently, the LTE system has a handover delay problem.

The present invention was made taking into account the problem described above and an objective of the present invention is to provide a method of mobile communication, a radio base station and an upper node which are able to reduce a delay in the handover allowing a eNB handover target radio base station use an UE Context aided by an eNB handover source radio base station, in handover.

A first aspect of the present invention is summarized as a mobile communication method for handovering a mobile station from a radio base station to another radio base station other than the radio base station in a mobile communication system including a plurality of stations radio base station and an upper node of the plurality of radio base stations, in which the upper node and a handover source radio base station store configuration information about an access terminal having been configured between the upper node and the handover source radio base station, the mobile communication method including the steps of:

(A) inform, from the handover source radio base station to a handover target radio base station, the access terminal configuration information; (B) store, in the handover target radio base station, the access terminal configuration information informed by the handover target radio base station; and (C) establishing, on the upper node, an access terminal between the upper node and the handover target radio base station using the configuration information stored in the access terminal without performing relocation processing of the new terminal configuration information. of access, the access terminal being configured in response to a request to change the path of the handover target radio base station.

In the first aspect, each of the access terminals can be a tunnel used for user data transmission and the configuration information of the access terminal can be a GTP-U TE-ID on the upper node side in the tunnel.

In the first aspect, in step (A), the handover source radio base station can inform the target handover radio base station about an IP address for the upper node, in addition to the configuration information of the access terminal.

In the first aspect, in step (A), the handover source radio base station can transmit the configuration information from the access terminal to the handover target radio base station by the fact that the access terminal configuration information is contained in a message requesting the handover target radio base station to perform the handover.

In the first aspect, in step (B), the handover target radio base station can select the access terminal configuration information that can be assigned to the handover target radio base station from the access terminal configuration information informed by the handover target radio base station and store the configuration information of the access terminal so selected.

In the second aspect of the present invention, it is summarized as a radio base station used in a mobile communication system in which a mobile station's handover can be performed, the radio base station including: a handover control unit configured to transmit a message to a target handover radio base station when a predetermined condition is met with respect to the quality of communication at the mobile station, the message asking the target handover radio base station to perform the handover, in which the handover control unit is configured to transmit a GTP-U TE-ID on the upper node side in a tunnel because it has the TE-ID contained in the message, the tunnel having been established between the radio base station and an upper node of the radio base station and being used for user data transmission.

A second aspect of the present invention is summarized as a radio base station used in a mobile communication system in which a mobile station's handover can be performed, the radio base station including: a handover control unit configured to establish a tunnel for user data transmission between the radio base station and an upper node of the radio base station when it received a message from a handover target radio base station, the message requesting that the radio base station performs the handover, wherein the handover control unit is configured to tunnel between the radio base station and the upper node using a GTP-U TE-ID on the upper node side in a tunnel established between the source radio base station handover and the upper node, the TE-ID being contained in the message.

A third aspect of the present invention is summarized as an upper node of a plurality of radio base stations used in a mobile communication system in which handover of a mobile station can be performed, in which the upper node is configured to store information configuration over an access terminal having been configured between the upper node and a handover source radio base station, the upper node is configured to establish the stored access terminal configuration information without reallocating new access terminal configuration information.

As described above, the present invention can provide a method of mobile communication, a radio base station and an upper node which are capable of reducing a handover delay by allowing an eNB handover target radio base station to use an UE context. assisted by an eNB handover source radio base station, in handover.

Brief Description of Drawings

Figure 1 is a diagram of the entire configuration of an IMT 2000 system.

Figure 2 is a sequence diagram showing handover operations in a next generation mobile communication system.

Figure 3 is a diagram of the entire configuration of a mobile communication system according to a first embodiment of the present invention.

Figure 4 is a functional block diagram of an eNB according to the first embodiment of the present invention.

Figure 5 is a functional block diagram of an SAE Door according to the first embodiment of the present invention.

Figure 6 is a diagram in sequence showing handover operations in the mobile communication system according to the first embodiment of the present invention.

Figure 7 is a flow chart showing an operation of the eNB according to the first embodiment of the present invention.

Figure 8 is a flow chart showing an operation of the eNB according to the first embodiment of the present invention.

Figure 9 is a flow chart showing an operation of the SAE Gate according to the first embodiment of the present invention.

Best Mode for Carrying Out the Invention (Configuration of the Mobile Communication System According to the First Modality of the Present Invention)

A first embodiment of the present invention will be described with reference to figures 3 to 5.

A mobile communication system according to this modality is operable to implement a communication technology used during handover, in particular operable to implement a communication technology of an access terminal which is established between a radio base station (here after eNB ) and an upper node (here after Porta SAE).

In this modality, description will be provided taking, as an example, a mobile communication system including, as shown in figure 3, an LTB / SAE architecture of which standardization has been carried out at 3GPP. However, the present invention is not limited to the above mobile communication system and is applicable to a mobile communication system including another architecture.

A radio access network is composed of multiple eNBs and a central node MME / SAE Port to which the eNBs are connected.

Here, an MME is a node that handles control data and an SAE Port is a node that handles user data.

Note that, although the eNBs are connected to each other via interfaces called X2 interfaces, each eNB and the MME / SAE Port are connected to each other via an interface called an S1 interface.

Data in the control plane (C-plane) (control data) and data in the user plane (U-plane) (user data) are transmissible over an X2 interface or an S1 interface.

In particular, data in the user plane is transmitted via GTP-U / UDP and a GTP tunnel used for data transmission in the user plane is established between an eNB and the SAE Port having TE-IDs exchanged between them.

As shown in figure 4, each of the eNBs, according to the present embodiment, includes a control unit 101, a wired transmission unit 102, a handover control unit 103 and a context management unit 104.

The control unit 101 is configured to control operations of the respective function units 102 to 104.

Wired transmission unit 102 is configured to transmit and receive control data and user data via a wired transmission path.

The context management unit 104 is configured to contain a UE Context containing a GTP-U TE-ID (access terminal configuration information) for identification of each mobile station (here after UE) on an SAE Access Terminal (an access terminal established between eNB and Porta SAE.

The handover control unit 103 is configured to perform signaling during handover.

For example, handover control unit 103 is an eNB handover source configured to report an eNB₂ handover target of an UE Context (containing access terminal configuration information, such as a GTP-U TE-ID on the SAE Port side in a GTP tunnel) of a handover in question.

Specifically, the handover control unit 103 is configured to transmit a Handover Request message when it is considered, based on a measurement transmission message transmitted from the EU, that the quality of communication in the EU satisfies a predetermined condition, the message Handover Request requesting that eNB₂ handover target perform the handover.

Additionally, the handover control unit 103 can be configured to transmit a TE-ID on the side of the SAE Port in a GTP tunnel having the TE-ID, according to the configuration information of the access terminal described above, contained in Handover Request message, the GTP tunnel having been established between eNB and the SAE Port, which is a superior node of eNB.

Additionally, the handover control unit 103 can be configured to inform the eNB2 handover target of an IP address for the SAE Port (an address for the upper node), in addition to the access terminal configuration information described above.

The handover control unit 103 in the handover target eNB2 is configured to establish a GTP tunnel between the eNB₂ handover target and the SAE Port when having received an eNB message₂ handover source requesting that eNB₂ handover target perform the handover.

Specifically, the handover control unit 103 above is configured to establish the GTP tunnel between the eNB₂ handover target and the SAE Port using the TE-ID, which is contained in the Handover Request message, on the SAE Port side in the GTP tunnel that was established between the handover source eNBi and the SAE Port.

Here, the handover control unit 103 above is configured to perform relocation processing with respect to a TE-ID on the eNB side.₂ handover target in the GTP tunnel above.

Note that, since ΤΕ-IDs can be independently allocated to the respective eNBs, the handover control unit 103 above is configured to allocate the same TE-ID as the TE-ID reported by eNB! handover source, that is, the TE-ID on the eNB side₂ handover target in the GTP tunnel above.

Additionally, the handover control unit 103 above is configured to inform the SAE Port of the allocated TE-ID (access terminal configuration information) on the eNB side₂ handover target and an IP address for eNB₂ handover target using a Full Handover message.

Additionally, the handover control unit 103 at eNB₂handover target can be configured to select the configuration information of the access terminal (a TE-ID on the side of the eNB₂) that can