Communication control method, gateway apparatus, and user terminal

A communication control method according to the present embodiment comprises the steps of: relaying, by a gateway apparatus in a cellular network, user data from an external network to a user terminal connecting to the cellular network; switching an accommodation target of traffic of the user terminal from the cellular network to another network not managed by an operator managing the cellular network; and relaying, by the gateway apparatus, on a basis of a location of the user terminal in the another network, the user data to the user terminal, via the another network.

TECHNICAL FIELD

The present disclosure relates to a communication control method, a gateway apparatus, and a user terminal used in a communication system capable of switching an accommodation target of traffic of a user terminal from a cellular network to another network.

BACKGROUND ART

In recent years, the use of a user terminal capable of connecting not only to a cellular network but also to another network expands. For example, the use of a user terminal (so-called dual terminal) capable of connecting to a cellular network and a wireless LAN (Local Area Network) expands, and therefore, in 3GPP (3rd Generation Partnership Project) which is a project aiming to standardize a cellular communication system, a technology is being considered which is capable of strengthening cooperation between a cellular RAN (Radio Access Network) and a wireless LAN (see Non Patent Document 1).

In such a user terminal, it is possible to switch an accommodation target of traffic of a user terminal from a cellular network to another network. As a result, it is possible to reduce traffic load of a cellular network (offload).

PRIOR ART DOCUMENT

SUMMARY

An object of the present disclosure is to provide a communication control method, a gateway apparatus, and a user terminal capable of realizing a seamless offload when an accommodation target of traffic of a user terminal is switched from a cellular network to another network (network not managed by an operator managing the cellular network, for example).

A communication control method according to an embodiment comprises the steps of: relaying, by a gateway apparatus in a cellular network, user data from an external network to a user terminal connecting to the cellular network; switching an accommodation target of traffic of the user terminal from the cellular network to another network not managed by an operator managing the cellular network; and relaying, by the gateway apparatus, on a basis of a location of the user terminal in the another network, the user data to the user terminal, via the another network.

DESCRIPTION OF THE EMBODIMENT

Overview of Embodiment

A communication control method according to an embodiment comprises the steps of: relaying, by a gateway apparatus in a cellular network, user data from an external network to a user terminal connecting to the cellular network; switching an accommodation target of traffic of the user terminal from the cellular network to another network not managed by an operator managing the cellular network; and relaying, by the gateway apparatus, on a basis of a location of the user terminal in the another network, the user data to the user terminal, via the another network.

The communication control method according to an embodiment further comprises: registering, by the gateway apparatus, the location of the user terminal in the another network, when being requested from the user terminal to register the location of the user terminal.

The communication control method according to an embodiment further comprises: requesting, by the user terminal, on a basis of a global address of the gateway apparatus, the gateway apparatus to register the location of the user terminal.

The communication control method according to an embodiment further comprises: registering, by the gateway apparatus, when receiving information on the location of the user terminal in the another network from the user terminal, the location of the user terminal in the another network, on a basis of information.

In the embodiment, it comprises the steps of: acquiring, by the user terminal, an address of a home agent managing the location of the user terminal; and inquiring, by the user terminal, the cellular network of whether or not the address of the home agent is the global address of the gateway apparatus in the cellular network. In the requesting, when the address of the home agent is the global address of the gateway apparatus, the user terminal requests registration of the location of the user terminal.

The communication control method according to an embodiment further comprises the steps of: notifying, by the user terminal, the cellular network of identification information of a communication node of a connection target in the another network; and receiving, by the user terminal, the global address of the gateway apparatus from the cellular network when the communication node is not a communication node managed by the operator.

The communication control method according to an embodiment further comprises the steps of: receiving, by the user terminal, first information including identification information of a wireless LAN access point from a server managing ANDSF information on a wireless LAN; determining, by the user terminal, whether or not identification information of a wireless LAN access point of a connection target in the another network is included in the first information; and requesting, by the user terminal, to the cellular network, the global address of the gateway apparatus when determining that the identification information of the wireless LAN access point of the connection target is not included in the first information.

The communication control method according to an embodiment further comprises the steps of: acquiring, by the user terminal, an address of a home agent managing the location of the user terminal, and transmitting the address of the home agent to the cellular network; determining, by the cellular network, whether or not the address of the home agent is the global address of the gateway apparatus; determining, by the cellular network, whether or not the user data is relayed via the home agent before the accommodation target of the traffic is switched; maintaining, by the user terminal, connection with the cellular network even after the switching, when it is determined that the acquired address of the home agent is not the global address of the gateway apparatus and the user data is not relayed via the home agent; receiving, by the user terminal, even after the switching, via the cellular network from the gateway apparatus, user data on communication started by the user terminal before the switching; and receiving, by the user terminal, via the another network from a network apparatus different from the gateway apparatus, user data on communication newly started by the user terminal after the switching.

The communication control method according to an embodiment further comprises the steps of: maintaining, by the user terminal, connection with the cellular network even after the switching, when it is not possible for the user terminal to acquire the global address of the gateway apparatus; receiving, by the user terminal, even after the switching, via the cellular network from the gateway apparatus, user data on communication started by the user terminal before the switching; and receiving, by the user terminal, via the another network from a network apparatus different from the gateway apparatus, user data on communication newly started by the user terminal after the switching.

A gateway apparatus according to an embodiment is a gateway apparatus in a cellular network, and is used in a communication system capable of switching an accommodation target of traffic of a user terminal from the cellular network to another network. The gateway apparatus comprises: a controller configured to relay user data from an external network to the user terminal connecting to the cellular network. After the accommodation target of the traffic of the user terminal is switched from the cellular network to the another network not managed by an operator managing the cellular network, the controller relays, on a basis of a location of the user terminal in the another network, via the another network, the user data to the user terminal.

A user terminal according to an embodiment is a user terminal used in a communication system capable of switching an accommodation target of traffic of a user terminal from a cellular network to another network. The user terminal comprises: a receiver configured to receive, while being connected to the cellular network, user data that is relayed from a gateway apparatus in the cellular network and that is from an external network; and a controller configured to request, after the accommodation target of the traffic of the user terminal is switched from the cellular network to the another network not managed by an operator managing the cellular network, the gateway apparatus to register a location of the user terminal in the another network. The receiver receives the user data via the another network from the gateway apparatus.

In the embodiment, the controller transmits, when requesting the gateway apparatus to register the location of the user terminal in the another network, information on the location of the user terminal in the another network, to the gateway apparatus.

Embodiment

Hereinafter, with reference to the drawings, embodiments will be described in which a cellular communication system (LTE system) configured to comply with the 3GPP standards is cooperated with a wireless LAN (WLAN) system.

FIG. 1is a system configuration diagram according to the embodiment. As shown inFIG. 1, a cellular communication system includes a plurality of UEs (User Equipments)100, an E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network)10, and an EPC (Evolved Packet Core)20.

The E-UTRAN10corresponds to a cellular RAN. The EPC20corresponds to a core network. The E-UTRAN10and the EPC20configure a network (cellular network) of the cellular communication system.

The UE100is a mobile-type radio communication apparatus and performs radio communication with a cell with which a connection is established. The UE100corresponds to a user terminal. The UE100is a terminal (dual terminal) that supports both communication schemes of cellular communication and WLAN communication.

The E-UTRAN10includes a plurality of eNBs200(evolved Node-Bs). The eNB200corresponds to a cellular base station. The eNB200manages one cell or a plurality of cells, and performs radio communication with the UE100with which a connection is established with a cell of the eNB200. It is noted that the “cell” is used as a term indicating a minimum unit of a radio communication area, and is also used as a term indicating a function of performing radio communication with the UE100. Furthermore, the eNB200has a radio resource management (RRM) function, a routing function of user data, and a measurement control function for mobility control and scheduling, for example.

The eNB200is connected mutually via an X2 interface. Furthermore, the eNB200is connected, via an S1 interface, to an MME (Mobility Management Entity)/S-GW (Serving-Gateway)500included in the EPC20.

The EPC20includes a plurality of MME/S-GWs500and PGWs (Packet Data Network Gateways)700. The MME is a network node that performs various mobility controls, for example, for the UE100and corresponds to a controller. The S-GW is a network node that performs control to transfer user data and corresponds to a mobile switching center. The PGW700is a network node that controls to relay user data from an external network (and to an external network) not managed by an operator of the cellular network. In the present embodiment, the PGW700has a function, as an HA (Home Agent), of managing the location of the UE100. Furthermore, the PGW700functions as an LMA (Local Mobility Anchor) that switches a communication route to map an existing area of the UE100and relays the user data of the UE100to the existing area. Specifically, the PGW700transfers the user data to an MAG (Mobility Access Gateway) in a network to which the UE100is connected.

A WLAN30includes a WLAN access point (hereinafter, briefly referred to as “AP”)300. Specifically, a WLAN30-1includes an AP managed by an operator of a cellular network (Operator controlled AP), and is supported by the operator of the cellular network. On the other hand, a WLAN30-2includes an AP300-2not managed by the operator of the cellular network, and is not supported by the operator of the cellular network.

The WLAN30is configured to comply with standards of IEEE 802.11, for example. The AP300performs communication with the UE100in a frequency band (WLAN frequency band) different from a cellular frequency band. The AP300is connected, via a router or the like, to the EPC20.

Furthermore, in addition to a case where the eNB200and the AP300are individually located, the eNB200and the AP300may also be “Collocated”. As one mode of the “Collocated”, the eNB200and the AP300may be directly connected to each other through any interface of an operator.

The EPC20further includes an ANDSF (Access Network Discovery and Selection Function) server600. The ANDSF server600manages ANDSF information on the WLAN30. The ANDSF server600provides the UE100with the ANDSF information on the WLAN30, by an NAS (Non Access Stratum) message.

It is noted that the ANDSF server600utilized by the UE100in an H-PLMN (Home Public Land Mobile Network) is called an H-ANDSF server. The ANDSF server600utilized, during roaming, by the UE100in a V-PLMN (Visited Public Land Mobile Network) is called a V-ANDSF server.

Next, configurations of the UE100, the eNB200, and the AP300will be described.

FIG. 2is a block diagram of the UE100. As shown inFIG. 2, the UE100includes: antennas101and102; a cellular communication unit111; a WLAN communication unit112; a user interface120; a GNSS (Global Navigation Satellite System) receiving equipment130; a battery140; a memory150; and a processor160. The memory150and the processor160configure a controller. The UE100may not include the GNSS receiving equipment130. Furthermore, the memory150may be integrally formed with the processor160, and this set (that is, a chip set) may be called a processor160′.

The antenna101and the cellular communication unit111are used for transmitting and receiving a cellular radio signal. The cellular communication unit111converts a baseband signal output from the processor160into a cellular radio signal, and transmits the same from the antenna101. Furthermore, the cellular communication unit111converts a cellular radio signal received by the antenna101into a baseband signal, and outputs the same to the processor160.

The antenna102and the WLAN communication unit112are used for transmitting and receiving a WLAN radio signal. The WLAN communication unit112converts a baseband signal output from the processor160into a WLAN radio signal, and transmits the same from the antenna102. Furthermore, the WLAN communication unit112converts the WLAN radio signal received by the antenna102into the baseband signal, and outputs the same to the processor160.

The user interface120is an interface with a user carrying the UE100, and includes a display, a microphone, a speaker, and various buttons, for example. Upon receipt of the input from a user, the user interface120outputs a signal indicating a content of the input to the processor160. The GNSS receiving equipment130receives a GNSS signal in order to obtain location information indicating a geographical location of the UE100, and outputs the received signal to the processor160. The battery140accumulates power to be supplied to each block of the UE100.

The memory150stores a program to be executed by the processor160and information to be used for a process by the processor160. The processor160includes a baseband processor that performs modulation and demodulation, encoding and decoding, and the like on the baseband signal and a CPU that performs various types of processes by executing the program stored in the memory150. The processor160may further include a codec that performs encoding and decoding on sound and video signals. The processor160executes various types of processes and various types of communication protocols described later.

FIG. 3is a block diagram of the eNB200. As shown inFIG. 3, the eNB200includes an antenna201, a cellular communication unit210, a network interface220, a memory230, and a processor240. The memory230and the processor240configure a controller. It is noted that the memory230may be integrally formed with the processor240, and this set (that is, a chipset) may be called a processor.

The antenna201and the cellular communication unit210are used for transmitting and receiving a cellular radio signal. The cellular communication unit210converts a baseband signal output from the processor240into a cellular radio signal, and transmits the same from the antenna201. Furthermore, the cellular communication unit210converts a cellular radio signal received by the antenna201into a baseband signal, and outputs the same to the processor240.

The network interface220is connected to a neighboring eNB200via the X2 interface and is connected to the MME/S-GW500via the S1 interface. Furthermore, the network interface220is used for communication with the AP300via the EPC20.

The memory230stores a program to be executed by the processor240and information to be used for a process by the processor240. The processor240includes a baseband processor that performs modulation and demodulation, encoding and decoding, and the like on the baseband signal and a CPU that performs various types of processes by executing the program stored in the memory230. The processor240executes various types of processes and various types of communication protocols described later.

FIG. 4is a block diagram of the AP300. As shown inFIG. 4, the AP300includes an antenna301, a WLAN communication unit311, a network interface320, a memory330, and a processor340.

The antenna301and the WLAN communication unit311are used for transmitting and receiving a WLAN radio signal. The WLAN communication unit311converts a baseband signal output from the processor340into a WLAN radio signal, and transmits the same from the antenna301. Furthermore, the WLAN communication unit311converts a WLAN radio signal received by the antenna301into a baseband signal, and outputs the same to the processor340.

The network interface320is connected to the EPC20via a router, and the like. Furthermore, the network interface320is used for communication with the eNB200via the EPC20.

The memory330stores a program to be executed by the processor340and information to be used for a process by the processor340. The processor340includes a baseband processor that performs modulation and demodulation, encoding and decoding, and the like on the baseband signal and a CPU that performs various types of processes by executing the program stored in the memory330.

FIG. 5is a protocol stack diagram of a radio interface in the LTE system. As illustrated inFIG. 5, the radio interface protocol is classified into a layer 1 to a layer 3 of an OSI reference model, wherein the layer 1 is a physical (PHY) layer. The layer 2 includes a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer. The layer 3 includes an RRC (Radio Resource Control) layer.

The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Between the PHY layer of the UE100and the PHY layer of the eNB200, data is transmitted via the physical channel.

The MAC layer performs preferential control of data, and a retransmission process and the like by hybrid ARQ (an HARQ). Between the MAC layer of the UE100and the MAC layer of the eNB200, data is transmitted via a transport channel. The MAC layer of the eNB200includes a scheduler that selects an uplink and downlink transport format (a transport block size, a modulation and coding scheme and the like) and an assignment resource block.

The RLC layer transmits data to an RLC layer of a reception side by using the functions of the MAC layer and the PHY layer. Between the RLC layer of the UE100and the RLC layer of the eNB200, data is transmitted via a logical channel.

The RRC layer is defined only in a control plane. Between the RRC layer of the UE100and the RRC layer of the eNB200, a control message (an RRC message) for various types of setting is transmitted. The RRC layer controls the logical channel, the transport channel, and the physical channel in response to establishment, re-establishment, and release of a radio bearer. When a connection (an RRC connection) is established between the RRC of the UE100and the RRC of the eNB200, the UE100is in a connection state (an RRC connection state) of cellular communication, and when the RRC connection is not established, the UE100is in an idle state (an RRC idle state) of the cellular communication.

A NAS (Non-Access Stratum) layer positioned above the RRC layer performs session management or mobility management, for example. The MME300and the ANDSF server600transmit and receive a NAS message from and to the UE100.

(Operation According to Embodiment)

An operation according to the embodiment will be described, below.

(1) Operation Overview

FIGS. 6(A) to 6(C)are diagrams for describing an operation overview according to the embodiment.FIG. 6(A)is a diagram for describing a user data relay before the accommodation target of the traffic is switched.FIG. 6(B)is a diagram for describing a user data relay after the accommodation target of the traffic is switched to a wireless LAN network managed by a common operator.FIG. 6(C)is a diagram (part1) for describing a user data relay after the accommodation target of the traffic is switched to a wireless LAN network managed by a different operator.

InFIGS. 6(A) to 6(C), there are two types of wireless LAN networks configured by a WAG350(WAG350-1/WAG350-2) and a WLAN AP (AP300-1/AP300-2). One wireless LAN network (hereinafter, referred to as first wireless LAN network, where appropriate) is a network managed by an operator that manages the cellular network. Therefore, the first wireless LAN network and the cellular network are common in operator service. The other wireless LAN network (hereinafter, referred to as second wireless LAN network, where appropriate) is a network not managed by the operator that manages the cellular network.

Here, the WAG350is a gateway apparatus (WAG: WLAN Access Gateway) in the wireless LAN network, and relays the user data from the external network. Furthermore, the WAG350-1included in the wireless LAN network common in operator service corresponds to an MAG, and receives the user data from a PGW700corresponding to an LMA.

Firstly, as shown inFIG. 6(A), before switching the accommodation target of the traffic of the UE100, the UE100performs communication with a server800connected via the external network, and transmits and receives the user data with the server800. The UE100is connected to the eNB200. The UE100transmits and receives the user data through a data path via the PGW700and the eNB200.

Next, when the accommodation target of the traffic of the UE100is switched from the cellular network to the first wireless LAN network, as shown inFIG. 6(B), the UE100is connected to the AP300-1. In this case, the UE100transmits and receives the user data through a data path via the PGW700, the WAG350-1, and the AP300-1.

The cellular network and the first wireless LAN network are common in operator, and thus, it is possible to previously set the WAG350-1that functions as the MAG, to the PGW700, for example. As a result, the PGW700is capable of relaying the user data to the WAG350-1.

Next, when the accommodation target of the traffic of the UE100is switched from the cellular network to the second wireless LAN network, as shown inFIG. 6(C), the UE100is connected to the AP300-2. In this case, the UE100transmits and receives the user data through a data path via the PGW700, the WAG350-2, and the AP300-2. That is, the user data received by the PGW700is not discarded, but is relayed via the WAG350-2to the UE100, and thus, the UE100is capable of receiving, without discontinuation, the user data. As a result, even when the accommodation target of the traffic of the UE100is switched from the cellular network to the second wireless LAN network, it is possible to realize a seamless offload.

An operation by the PGW700to relay the user data to the WAG350-2will be described later.

(2) Operation Sequence

Next, operation sequences1to4that are operation sequences according to the embodiment will be described by usingFIGS. 7 to 10.FIG. 7is a sequence diagram for describing the operation sequence1according to the embodiment.FIG. 8is a sequence diagram for describing the operation sequence2according to the embodiment.FIG. 9is a sequence diagram for describing the operation sequence3according to the embodiment.FIG. 10is a sequence diagram for describing the operation sequence4according to the embodiment.

The UE100is connected to the eNB200included in the cellular network and performs communication with the server800.

In step S101, the eNB200transmits, to the UE100, an offload command to transit the traffic of the UE100. The UE100receives the offload command.

The UE100-1that receives the offload command compares information (received signal intensity and load information, for example) measured from the AP300with a threshold value, and decides the AP300of an offload target. At this time, the UE100-1may refer to user preference information on a user preference recorded in the memory150, and use a threshold value in which the user preference is reflected in a numerical value so that the AP of user preference is preferentially selected (and decided) as the AP of the offload target.

Here, examples of the AP of user preference include AP not managed by the operator (AP of a home managed by the user of the UE100, etc.). The user preference information includes an identifier of the AP (SSID, etc.), an address of an HA (Home Agent) corresponding to the (identifier of) the AP, and the like. The address of the HA may be a global address of the PGW700. When the UE100is connected to the AP, the HA corresponding to the AP manages the location of the UE100and relays the user data.

The UE100may acquire the user preference information as a result of direct input by the user operation, and may acquire the user preference from a predetermined server as a result of a user inputting an address of the predetermined server.

Description proceeds on the assumption that the UE100decides, as the AP of the offload target, the AP300-2of user preference based on the user preference information, below.

In step S102, the UE100-1confirms on the basis of the user preference information whether or not to have an address of the HA corresponding to the AP300-2of the offload target.

When having the address of the HA corresponding to the AP300-2, the UE100-1executes a process of step S103. Description proceeds on the assumption that the address of the HA is a global address of the PGW700, below. It is noted that when not having the address of the HA corresponding to the AP300-2of the offload target, the UE100-1transmits and receives the user data through a data path not passing through the PGW700(not shown).

Next, the UE100ends the connection with the eNB200, and performs connection with the AP300-2of the offload target. The UE100establishes a new data path with the server800. Furthermore, the UE100acquires an address of the UE100in the wireless LAN network.

In step S103, the UE100requests the PGW700to register the location of the UE100, on the basis of the global address of the PGW700. Specifically, the UE100requests the location registration to the PGW700, via the wireless LAN network (that is, the AP300-2and the WAG350-2). The request for the location registration includes an identifier of the UE100and the address of the UE100in the wireless LAN network.

Here, the global address is an address unique not only to the cellular network but also to another network, and thus, the UE100is capable of accessing the PGW700from the wireless LAN network.

In step S104, the PGW700registers the location of the UE100in the wireless LAN network, on the basis of the request for the location registration from the UE100. Specifically, the PGW700registers, in a location management list, the identifier of the UE100and the address of the UE100in the wireless LAN network in an associated manner.

In step S105, the PGW700transmits a response to the request for the location registration (location registration response), to the UE100. The PGW700transmits the location registration response to the UE100via the wireless LAN network, on the basis of the address of the UE100in the wireless LAN network. The UE100knows that the location of the UE100is registered in the PGW700as a result of receiving the location registration response.

Thereafter, the PGW700relays, on the basis of the address of the UE100in the wireless LAN network, the user data of the UE100received from the server800, to the UE100via the WAG350-2. The UE100is capable of receiving the user data transmitted to the PGW700, and thus, it is possible to realize a seamless offload without a temporary communication breakdown.

Next, the operation sequence2will be described by usingFIG. 8. It is noted that a description will be provided while focusing on a portion different from the above-described operation sequence1, and a description of a similar portion will be omitted, where necessary.

In the operation sequence2, the UE100performs an operation for confirming whether or not the address of the HA is the global address of the PGW700.

It is noted that when it is already known that the address of the HA is the global address of the PGW700on the basis of past history information, for example, the UE100is capable of omitting the processes of steps S203and S204. In this case, the UE100executes the same process as that in the operation sequence1.

In step S203, when having the address of the HA corresponding to the AP300-2of the offload target, the UE100inquires the cellular network (specifically, the PGW700) of whether or not the address of the HA is the global address of the PGW700to which the connection is currently established. The information indicating this inquiry includes the address of the HA provided in the UE100.

The PGW700determines whether the address of the HA included in the information indicating the inquiry matches an address of the PGW700.

In step S204, the PGW700transmits a response to the inquiry, to the UE100. The response includes information indicating whether or not the HA address matches the address of the PGW700.

In the operation sequence2, the UE100performs the inquiry of the HA address, and thus, the UE100does not send the location registration request to an HA different from the connected PGW700after the accommodation target of the traffic of the UE100is switched to the wireless LAN network. Thus, it is possible to suppress the generation of unnecessary traffic.

Next, the operation sequence3will be described by usingFIG. 9. It is noted that a description will be provided while focusing on a portion different from the above-described operation sequence1, and a description of a similar portion will be omitted, where necessary.

In the operation sequences1and2, the UE100acquires the global address of the PGW700, on the basis of the user operation. On the other hand, in the operation sequence3, the UE100acquires the global address of the PGW700from the cellular network (specifically, the PGW700).

In step S302, the UE100notifies the PGW700of information (for example, SSID) indicating an identifier of the AP300-2to be connected in the offload target. The UE100may decide the identifier of the AP300-2of the offload target with reference to the user preference information, and the UE100may decide the identifier of the AP300-2of the offload target, on the basis of the identifier of the AP300-2included in the offload command.

In step S303, the PGW700determines whether or not the AP300-2indicated by the notified SSID is an AP managed by the operator. That is, the PGW700determines whether or not the operator managing the PGW700and the operator managing the AP300-2are in common. For example, the PGW700holds list information of the identifier (SSID) of the AP managed by the operator managing the PGW700, and compares the list information with the notified SSID to make the determination.

When determining that the AP300-2is not the AP managed by the operator, the PGW700executes a process of step S304. It is noted that when it is assumed that the AP of the offload target of the UE100is the AP300-1, the PGW700determines that the AP300-1is the AP managed by the operator. In this case, the PGW700relays the user data of the UE100received after the accommodation target of the traffic is switched, via the WAG350-1and the AP300-1.

In step S304, the PGW700notifies the UE100of the global address of the PGW700that functions as the HA. The UE100receives the global address of the PGW700.

In the operation sequence3, when connecting to the wireless LAN network not managed by the operator managing the cellular network, the UE100is capable of receiving the global address of the PGW700. That is, only when the location registration to the PGW700is needed, the UE100is capable of receiving the global address of the PGW700. Thus, it is possible to suppress the generation of unnecessary traffic.

Next, the operation sequence4will be described by usingFIG. 10. It is noted that a description will be provided while focusing on a portion different from the above-described operation sequence1, and a description of a similar portion will be omitted, where necessary.

In the above-described operation sequence3, when the AP300-2that is the connection target after the accommodation target of the traffic is switched is not the AP managed by the operator, the UE100receives the global address of the PGW700. On the other hand, in the operation sequence4, the UE100requests, on the basis of a predetermined condition, the global address of the PGW700to the cellular network (specifically, the PGW700).

As shown inFIG. 10, in step S401, the ANDSF server600transmits ANDSF information on the WLAN30, to the UE100. The UE100receives the ANDSF information while being connected to the cellular network. Description proceeds on the assumption that the ANDSF information includes the identifier of the AP. The AP indicated by the identifier of the AP included in the ANDSF information is an AP managed by the operator managing the cellular network.

Step S402corresponds to step S101.

In step S403, the UE100determines whether or not the AP300-2that is the connection target after the accommodation target of the traffic is switched is the AP included in the ANDSF information. Specifically, the UE100determines whether or not the identifier of the AP300-2matches the identifier of the AP included in the ANDSF information.

When the identifier of the AP300-2is not included in the ANDSF information, the UE100executes a process of step S404.

In step S404, the UE100requests, as the address of the HA, the global address of the PGW700to the PGW700. The PGW700receives the request.

In step S405, the PGW700notifies, on the basis of the request from the UE100, the UE100of the global address of the PGW700. The UE100receives the notification of the global address of the PGW700.

In the operation sequence4, when the identifier of the AP300-2is not included in the ANDSF information, the AP300-2is not managed by the operator managing the cellular network. Therefore, only when the location registration to the PGW700is needed, the UE100is capable of acquiring the global address of the PGW700. Thus, it is possible to suppress the generation of unnecessary traffic.

Other Embodiments

As described above, the present disclosure has been described with the embodiments. However, it should not be understood that those descriptions and drawings constituting a part of the present disclosure limit the present disclosure. From this disclosure, a variety of alternate embodiments, examples, and applicable techniques will become apparent to one skilled in the art.

In the above-described operation sequence2, when the address of the HA received from the UE100does not match the address of the PGW700, the PGW700only notifies the UE100of this unmatch; however, this is not limiting.

For example, when the address of the HA received from the UE100does not match the address of the PGW700, the PGW700may determine, before switching the accommodation target of the traffic, whether or not the user data of the UE100is relayed via the HA indicated by the address of the HA. Specifically, the PGW700determines whether or not the address of the HA received from the UE100matches an address of an apparatus that is a relay source relaying the user data of the UE100from the external network to the PGW700, or an address of an apparatus that is a relay target when relaying the user data from the UE100to the external network.

When determining that the user data of the UE100is not relayed via the HA indicated by the address of the HA, the PGW700requests to maintain the connection of the cellular network, to the UE100. When receiving the user data of the UE100, the PGW700relays the user data by way of the maintained connection. The PGW700relays the user data until the reception of the user data relayed via the HA is ended.

On the other hand, when receiving the request to maintain the connection of the cellular network, for example, the UE100maintains the connection of the cellular network. The UE100receives the user data on the communication started before switching the accommodation target of the traffic, via the cellular network, from the PGW700. When this communication is ended, the UE100ends the connection with the cellular network. On the other hand, the UE100performs connection with the wireless LAN network by switching the accommodation target of the traffic. The UE100receives the user data on the communication started after switching the accommodation target of the traffic, via the wireless LAN network, from the WAG350-2.

As a result, even when the address corresponding to the AP300-2based on the user preference information does not match the PGW700, it is possible to realize a seamless offload.

Furthermore, in either one of the cases, that is, when the UE100is not capable of acquiring the global address of the PGW700, when the PGW700does not provide a resource used for relaying the user data of another network, or when the PGW700does not publish the global address of the PGW700, as described above, the UE100receives the user data on the communication started before switching the accommodation target of the traffic, via the cellular network, from the PGW700, whereby it is possible to realize a seamless offload.

It is noted that when it is preferable that the UE100restarts receiving the user data from the accommodation target without the PGW700relaying the user data, the PGW700may determine to not relay the user data. For example, when a time requiring to compete the reception of the user data when the UE100restarts receiving the user data from the accommodation target is shorter than a time requiring to complete the reception of the user data when the PGW700performs the relay, the PGW700may determine, on the basis of estimated throughput in the wireless LAN network, to not relay the user data.

In the above-described embodiments, the PGW700registers the location of the UE100on the basis of the request for the location registration from the UE100; however, this is not limiting. For example, when transmitting the offload command to the UE100, the PGW700may acquire, via a third party server, the location information of the UE100in another network (a second wireless LAN network, for example). The PGW700is capable of registering the location of the UE100in the other network, on the basis of the acquired location information of the UE100. It is noted that the third party server is, for example, an authentication server that authenticates that the UE100is connected to the network, and manages the location of the UE100in each of a plurality of networks.

Furthermore, when receiving from the UE100information on the location of the UE100in another network (address of the UE100in the wireless LAN network, for example) without receiving the location registration request from the UE100, the PGW700may register, on the basis of the information, the location of the UE100in the other network.

In the above-described embodiments, a case is described where the accommodation target of the traffic of the user data is switched from the cellular network to the wireless LAN network; however, it is possible to use a method similar to the above-described method, even in a network other than the wireless LAN network.

In the above-described embodiments, as one example of cellular communication system, the LTE system is described; however, the present disclosure is not limited to the LTE system, and the present disclosure may be applied to systems other than the LTE system. In each operation sequence described above, the operation performed by the PGW700may be performed by, instead of the PGW700, another network apparatus that configures the cellular network such as the eNB200.

It is noted that the entire content of Japanese Patent Application No. 2013-264609 (filed on Dec. 20, 2013) is incorporated in the present specification by reference.

INDUSTRIAL APPLICABILITY

Thus, a communication control method, a gateway apparatus, and a user terminal according to the present embodiment, with which it is possible to realize a seamless offload when an accommodation target of traffic of the user terminal is switched from a cellular network to another network, are useful in a mobile communication field.