GB2582860A

GB2582860A - Communication apparatus, communication method, and program

Info

Publication number: GB2582860A
Application number: GB2002977.3A
Authority: GB
Inventors: Kurokawa Yasunari
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2019-03-12
Filing date: 2020-03-02
Publication date: 2020-10-07
Anticipated expiration: 2040-03-02
Also published as: GB2582860B; JP7342385B2; GB202002977D0; JP2020150348A

Abstract

A communication apparatus 100 comprising first 131 and second 133 communication processing sections in communication with one or more respective first and second network layer processing apparatus to process a first or second respective network layer; the second layer being higher than the first; an information obtaining section 135 to record connection failure occurrences with at least of the one second network layer apparatus; and a control section 137 configured to select and disconnect one of the first network layer apparatus when connection with one of the second network layer apparatus has failed. A method, computer program and computer-readable non-transitory recording medium having a program are also claimed. First network layer processing apparatus may be a radio access unit or femtocell base station (211, 212 fig.3) accommodated by the communication apparatus which may be another radio access network 611, 612 or gateway, respectively. The one or more second network layer processing apparatus may be core network nodes (311, 312 fig. 3) and may update in accordance with connection states stored on a state management table [60, fig 6].

Description

COMMUNICATION APPARATUS, COMMUNICATION METHOD, AND

PROGRAM

BACKGROUND

Technical Field

[0001] The present invention relates to a communication apparatus, a communication method, and a program.

Background Art

[0002] In mobile communication systems such as 3rd Generation (3G) and Long Term Evolution (LTE), introduction of a femtocell base station (Home NodeB, HNB) has been in process. The femtocell base station is a base station apparatus constituting a femtocell whose communication area has a radius of several tens of meters or less. Functions of the femtocell base station include complementing an area that is difficult to be covered by a wireless area of a macro base station, whose communication area has a radius of several kilometers, and providing a high-quality communication service at home or the like. Note that, in LTE, the femtocell base station is referred to as a Home eNodeB (HeNodeB) or an HeNB.

[0003] If a Mobility Management Entity (MATE) or a Serving Gateway (SGW) being a connection destination of an HeNB is in a state not capable of providing a service in such mobile communication systems, a terminal apparatus located in a serving area of a cell provided by the HeNB cannot transition to an available macro cell or an available cell of another HeNB, which has been posing a problem.

[0004] To address such a problem, for example, PTL 1 discloses a femto gateway that transmits a connection release request to a femtocell base station for releasing connection with a terminal that is connected to the femtocell base station, when the femto gateway detects communication failure with a core node [0005] [PTL I] WO 2015/045306

SUMMARY

[0006] However, not all lower network nodes (first network layer processing apparatuses) under a communication apparatus, such as the above-described gateway, are necessarily connected to a single higher network node (second network layer processing apparatus). Therefore, when failure occurs in any of second network layer processing apparatuses, the communication apparatus needs to appropriately control the first network layer processing apparatuses.

[0007] An example object of the present invention is to provide a communication apparatus, a communication method, and a program that enable appropriate control over operation of a first network layer processing apparatus which performs processing of a first network layer, even when failure occurs in a second network layer processing apparatus which performs processing of a second network layer which is higher than the first network layer.

[0008] According to one aspect of the present invention, a communication apparatus includes: a first communication processing section configured to communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; a second communication processing section configured to communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; an obtaining section configured to obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and a control section configured to specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0009] According to one aspect of the present invention, a communication method includes: communicating with one or more first network layer processing apparatuses which perform processing of a first network layer; communicating with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtaining information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specifying, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0010] According to one aspect of the present invention, a program is a program that causes a processor to: communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0011] According to one aspect of the present invention, a recording medium is a computer-readable non-transitory recording medium having recorded thereon a program that causes a processor to: communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0012] According to the present invention, appropriate control over operation of the first network layer processing apparatus which performs processing of the first network layer is possible, even when failure occurs in the second network layer processing apparatus which performs processing of the second network layer which is higher than the first network layer. Note that, according to the present invention, instead of or together with the above effects, other effects may be exerted.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Fig. 1 is a diagram for illustrating a reference example related to operation of an HeNB-GW and an HeNB when failure (connection abnormality) in an MIME is detected; Fig. 2 is a diagram for illustrating a reference example related to operation of an HeNB-GW and an HeNB when failure (connection abnormality) in an SGW is detected; Fig. 3 is an explanatory diagram illustrating an example of a schematic configuration of a system 1 according to a first example embodiment; Fig. 4 is a block diagram illustrating an example of a schematic configuration of an HeNB-GW 100 according to the first example embodiment; Fig. 5 is a sequence diagram for illustrating processing for establishing connection between the HeNB-GW 100 and MIVIEs 311 and 312; Fig. 6 illustrates a specific example of an MME state management table 60; Fig. 7 is a sequence diagram for illustrating processing for establishing connection between the HeNB-GW 100 and HeNBs 211 and 212; Fig. 8 is a diagram illustrating a specific example of an HeNB-MME mapping table 80 stored in a storage section 120, for example; Fig. 9 is a diagram illustrating an Attach sequence performed after S1 connections between the HeNBs 211 and 212 and the HeNB-GW 100 and SI connections between the HeNB-GW 100 and the MMEs 311 and 312 are established; Fig. 10 is a diagram illustrating a specific example of a UE-bearer mapping table stored in the storage section 120, for example; Fig. 11 is a diagram illustrating a sequence performed when Si connections between the HeNBs and the HeNB-GW and Si connections between the HeNB-GW and the MMEs are established, and subsequently abnormality occurs in any of the S1 connections between the HeNB-GW and the MMES; Fig. 12 is a diagram for illustrating a specific example of a sequence performed when abnormality occurs in connection in any of S1-U interfaces between the HeNB-GW and the SGWs; Fig. 13 is an explanatory diagram illustrating an example of a schematic configuration of a system 2 according to a second example embodiment of the present invention; Fig. 14 is a block diagram illustrating an example of a schematic configuration of a CU 500 according to the second example embodiment; Fig. 15 is a block diagram illustrating an example of a schematic configuration of a communication apparatus 1000 according to the second example embodiment; and Fig. 16 is a diagram illustrating some examples of MTC applications.

DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0014] Hereinafter, example embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the Specification and drawings, elements to which similar descriptions are applicable are denoted by the same reference signs, and overlapping descriptions may hence be omitted.

[0015]

Descriptions will be given in the following order.

1. Overview of Example Embodiments of Present Invention 2. First Example Embodiment 2.1. System Configuration 2.2. Configuration of HeNB-GW 100 2.3. Technical Features 2.4. Example Alterations 3. Second Example Embodiment 3.1. System Configuration 3.2. Configuration of CU 500 3.3. Technical Features 4. Third Example Embodiment 4.1. Configuration of Communication Apparatus 1000 4.2. Technical Features 5. Terminal Apparatus 6. Other Aspects [0016] Overview of Example Embodiments of Present Invention>> First, an overview of example embodiments of the present invention will be described.

[0017] (1) Technical Issues In mobile communication systems such as 3rd Generation (3G) and Long Term Evolution (LTE), introduction of a femtocell base station (Home NodeB, HNB) has been in process. The femtocell base station is a base station apparatus constituting a femtocell whose communication area has a radius of several tens of meters or less. Functions of the femtocell base station include complementing an area that is difficult to be covered by a wireless area of a macro base station, whose communication area has a radius of several kilometers, and providing a high-quality communication service at home or the like. Note that, in LTE, the femtocell base station is referred to as a Home eNodeB (HeNodeB) or an HeNB.

[0018] If a Mobility Management Entity (MME) or a Serving Gateway (SGW) being a connection destination of an HeNB is in a state not capable of providing a service in such mobile communication systems, a terminal apparatus located in a serving area of a cell provided by the HeNB cannot transition to an available macro cell or an available cell of another HeNB, which has been posing a problem.

[0019] For example, Fig. 1 is a diagram for illustrating a reference example related to operation of an HeNB-GW and an HeNB when failure in an MME (connection abnormality) is detected.

[0020] In the processing illustrated in Fig. 1, first, a call is established between a UE, an HeNB, an HeNB-GW, and a first MME (ST101). While a call is established as described above, the HeNB-GW detects a connection abnormality in a Stream Control Transmission Protocol (SCTP) layer being a transport layer on an Sl-MME interface between the HeNB-GW and the first MME (ST103).

[0021] Next, the HeNB-GW extracts UE(s) that has been connected to the MATE (first MME) in which the abnormality occurred, and executes an SI: UE Context Release procedure (TJE Context Release Command, UE Context Release Complete, RRC Connection Release) for the UE, to thereby perform call release (ST105, ST107, and ST109) [0022] Subsequently, the UE executes an RRC Connection Establishment procedure with the HeNB, and attempts call establishment again (ST111). In this case, also when a state of the first MME that is connected with the HeNB providing a service for the UE is a failure (connection abnormality) state, the 1.3E performs Attach Request to the HeNB (ST113). Subsequently, the HeNB transmits 51: Initial UE Message to the HeNB-GW (ST113). Subsequently, the HeNB-GW returns S1: Error Indication, which is a negative response to Si: Initial UE Message (ST115). In this manner, the call establishment processing fails.

[0023] From the viewpoint of the UE that failed in the above-described call establishment processing, the HeNB with which the UE attempted the call establishment provides radio coverage of the most satisfactory quality. Therefore, the UE repeatedly attempts call establishment with the same HeNB and HeNB-GW. However, the call establishment processing will continue to fail until a connectable ATME recovers.

[0024] Fig. 2 is a diagram for illustrating a reference example related to operation of an HeNB-GW and an HeNB when failure (connection abnormality) in an SGW is detected.

[0025] In the processing illustrated in Fig. 2, first, a call and bearers are established between a UE, an HeNB, an HeNB-GW, an MME, and an SGW (ST201).

[0026] The HeNB-GW periodically transmits GTP-U: Echo Request to the SGW with which a bearer(s) is established, for the purpose of normality confirmation (ST203). When GTP-U: Echo Response is not returned from the SGW within a certain period of time, the HeNB-GW retransmits Echo Request (ST205). Here, when a retransmission period expires, such as when the number of times of retransmission reaches a predetermined number, all E-UTRAN Radio Access Bearers (E-RABs) established with the SGW are released through an E-RAB Release procedure (ST207).

[0027] After the E-RABs are released, the UE immediately attempts re-establishment of an E-RAB with the same HeNB and HeNB-GW (ST209). However, the re-establishment processing will continue to fail if there is no available SGW.

[0028] Further, not all the HeNBs under the HeNB-GW are necessarily connected to a single core network node (such as an MME and an SGW) Therefore, the HeNB-GW needs to appropriately control the HeNBs under the HeNB-GW.

[0029] Also when a base station includes a center/central unit and radio units in the 5th Generation (5G) radio access network or the like, not all the radio units under the center/central unit are necessarily connected to a single core network node.

[0030] In view of this, for example, one example object of the following example embodiments is to enable appropriate control over operation of a first network layer processing apparatus which performs processing of a first network layer, even when failure occurs in a second network layer processing apparatus which performs processing of a second network layer which is higher than the first network layer. [0031] (2) Technical Features The present example embodiments includes: for example, communicating with one or more first network layer processing apparatuses which perform processing of a first network layer; communicating with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtaining information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specifying, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with a second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0032] According to the above configuration, for example, appropriate control over operation of the first network layer processing apparatus which performs processing of the first network layer is enabled, even when failure occurs in the second network layer processing apparatus which performs processing of the second network layer which is higher than the first network layer.

[0033] Note that the above-described technical features are concrete examples of the example embodiments of the present invention, and the present example embodiments of the present invention are, of course, not limited to the above-described technical features.

[0034] <<2. First Example Embodiment>> Next, with reference to Fig. 3 to Fig. 12, a first example embodiment will be described.

[0035] <2.1. System Configuration> With reference to Fig. 3, an example of a configuration of a system 1 according to the first example embodiment will be described. Fig. 3 is an explanatory diagram illustrating an example of a schematic configuration of the system 1 according to the first example embodiment. With reference to Fig. 3, the system 1 includes a small cell system la, a macro cell system lb, and a User Equipment 400 (UE).

[0036] For example, the system 1 is a system conforming to 3rd Generation Partnership Project (3GPP) standards/specifications. More specifically, for example, the system 1 may be a system conforming to LTE/LTE-Advanced and/or System Architecture Evolution (SAE) standards/specifications. Alternatively, the system 1 may be a system conforming to 5th Generation (56)/ New Radio (NR) standards/specifications. The system 1 is, of course, not limited to these examples. [0037] (Small Cell System la) For example, the small cell system la includes an HeNB-GW 100, HeNBs 211 and 212, MMEs 311 and 312, and SGWs 321 and 322. In the small cell system la as described above, the MMES 311 and 312 and the SGWs 321 and 322 constitute a core network. Specifically, each of the MMES 311 and 312 is an apparatus that performs signal control and UE mobility management in the core network, and the MN/1Es 311 and 312 perform processing of setting up user data channels between their respective SGWs 321 and 322 and the HeNB-GW 100. Each of SGWs 321 and 322 is an apparatus that transmits user data in the core network.

[0038] The HeNB-GW 100 is connected to each of the SGWs 321 and 322 via an S1-U interface, and is connected to each of the MMEs 311 and 312 via an S1-MME interface. Further, the HeNB-GW 100 is connected to each of the HeNBs 211 and 212 via an S1 interface. The HeNB-GW 100 is a gateway which accommodates a plurality of HeNBs (for example, the HeNBs 211 and 212), and relays a control signal to and from the MMEs and user data to and from the SGWs.

[0039] For example, each of the HeNBs 211 and 212 is an LTE small cell base station that is assumed to be installed in an office floor of a company or a general home. The HeNBs 211 and 212 respectively configure cells 51 and 52 as communication coverage, and perform radio communication with UE(s) located in respective cells.

[0040] (Macro Cell System lb) The macro cell system lb includes a base station 213, an MME 313, and an SGW 323. In the macro cell system lb as described above, the MATE 313 and the SGW 323 constitute a core network. Specifically, the MME 313 is an apparatus that performs signal control and UE mobility management in the core network, and performs processing of setting up a user data channel(s) between the SGW 323 and the base station 213. The SGW 323 is an apparatus that transmits user data in the core network. [0041] The base station 213 is connected to the SGW 323 via an S1-U interface, and is connected to the MME 313 via an SI -MME interface. For example, the base station 213 provides coverage wider than that of the small cell system la. For example, the base station 213 configures two cells 53 and 54.

[0042] For example, the base station 213 may be an evolved Node B (eNB) or a generation Node B (gNB) in 50. The base station 213 may include a plurality of units (or a plurality of nodes). The plurality of units (or the plurality of nodes) may include a first unit (or a first node) configured to perform higher protocol layer processing and a second unit (or a second node) configured to perform lower protocol layer processing. As an example, the first unit may be referred to as a center/central unit (CU), and the second unit may be referred to as a distributed unit (DU) or an access unit (AU). As another example, the first unit may be referred to as a digital unit (DU), and the second unit may be referred to as a radio unit (RU) or a remote unit (RU). The digital unit (DU) may be a base band unit (BBU), and the RU may be a remote radio head (RRH) or a remote radio unit (RRU). The terms for the first unit (or the first node) and the second unit (or the second node) are, of course, not limited to these examples. Alternatively, the base station 213 may be a single unit (or a single node). In this case, the base station 213 may be one of the plurality of units (e.g., either one of the first unit and the second unit) or may each be connected to another unit of the plurality of units (e.g., the other one of the first unit and the second unit).

[0043] (UE 400) In the example illustrated in Fig. 3, the UE 400 located in the cell 51 being coverage of the HeNB 211 of the small cell system la, and communicates with the SGW 321 and the MME 311 via the HeNB-GW 100. The UE 400 is also located in the cell 54 of the macro cell system lb. [0044] <2.2. Configuration of HeNB-GW 100> Next, with reference to Fig. 4, an example of a configuration of the HeNB-GW 100 according to the first example embodiment will be described. Fig. 4 is a block diagram illustrating an example of a schematic configuration of the HeNB-GW 100 according to the first example embodiment. With reference to Fig. 4, the HeNB-GW 100 includes a network communication section 110, a storage section 120, and a processing section 130.

[0045] (1) Network Communication Section 110 The network communication section 110 receives signals from a network, and transmits signals to the network.

[0046] (2) Storage Section 120 The storage section 120 temporarily or permanently stores programs (instructions) and parameters for operation of the HeNB-GW 100, as well as various data. The program includes one or more instructions for operation of the HeNB-GW 100.

[0047] (3) Processing Section 130 The processing section 130 provides various functions of the HeNB-GW 100. The processing section 130 includes a first communication processing section 131, a second communication processing section 133, an obtaining section 135, and a control section 137. Note that the processing section 130 may further include constituent elements other than these constituent elements. In other words, the processing section 130 may also perform operation other than the operation of these constituent elements. Specific operation of the first communication processing section 131, the second communication processing section 133, the obtaining section 135, and the control section 137 will be described later in detail.

[0048] (4) Implementation Example The network communication section 110 may be implemented with a network adapter and/or a network interface card, and the like. The storage section 120 may be implemented with a memory (e.g., a nonvolatile memory and/or a volatile memory) and/or a hard disk, and the like. The processing section 130 may be implemented with one or more processors. The first communication processing section 131, the second communication processing section 133, the obtaining section 135, and the control section 137 may be implemented with the same processor, or may be separately implemented with different processors. The memory (storage section 120) may be included in the one or more processors or may be provided outside the one or more processors.

[0049] The HeNB-GW 100 may include a memory configured to store a program (instructions) and one or more processors that can execute the program (instructions). The one or more processors may execute the program, and thereby perform operation of the processing section 130 (operation of the first communication processing section 131, the second communication processing section 133, the obtaining section 135, and/or the control section 137). The program may be a program for causing the processor(s) to execute operation of the processing section 130 (operation of the first communication processing section 131, the second communication processing section 133, the obtaining section 135, and/or the control section 137).

[0050] <2.3. Technical Features> Next, technical features of the first example embodiment will be described.

[0051] The HeNB-GW 100 (first communication processing section 131) communicates with one or more first network layer processing apparatuses which perform processing of a first network layer. The HeNB-GW 100 (second communication processing section 133) communicates with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer. The HeNB-GW 100 (obtaining section 135) obtains information on occurrence of failure in connection with the second network layer processing apparatus. The HeNB-GW 100 (control section 137) specifies a first network layer processing apparatus whose connection is set up with a second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on the occurrence of the failure. [0052] (1) First Network Layer Processing Apparatus For example, the first network layer processing apparatuses are femtocell base station, such as the HeNBs 211 and 212. Specifically, the HeNB-GW 100 is a gateway which accommodates femtocell base stations such as the HeNBs 211 and 212. For example, the HeNB-GW 100 (first communication processing section 131) transmits and/or receives a control signal to and from the HeNBs 211 and 212 via the Si interfaces, and transmits and receives user data to and from the HeNBs 211 and 212 via the SI-U interfaces.

[0053] (2) Second Network Layer Processing Apparatus For example, the second network layer processing apparatuses are core network nodes, such as the MMEs 311 and 312 or the SGWs 321 and 322. For example, the HeNB-GW 100 (second communication processing section 133) transmits and/or receives a control signal to and from the MMES 311 and 312 via the S1-MME interfaces, and transmits and/or receives user data to and from the SGWs 321 and 322 via the 51-U interfaces.

[0054] The HeNB-GW 100 (second communication processing section 133) manages and monitors the SI connection of each of the MMEs 311 and 312. Each time a state of any 51 connection is changed, for example, the HeNB-GW 100 (second communication processing section 133) updates an MATE state in an MIME state management table, which is managed in the storage section 120, to a state after the change.

[0055] In this case, for example, when the HeNB-GW 100 (first communication processing section 131) receives a connection request from an HeNB, the HeNB-GW 100 (first communication processing section 131) determines one MME to which the HeNB is to be connected, and reads a state of the MME to be connected from the NINIE state management table.

[0056] (3) Information on Occurrence of Failure For example, the HeNB-GW 100 (obtaining section 135) detects the occurrence of the failure in the connection with the second network layer processing apparatus, to obtain the information on the occurrence of the failure in the connection. Specifically, the HeNB-GW 100 (obtaining section 135) detects the occurrence of the failure in the connection with the second network layer processing apparatus with reference to the MME state management table, based on a state of the MME in the MME state management table.

[0057] (4) Control Related to Connection The HeNB-GW 100 (control section 137) manages bearers (communication channels) with each of the HeNBs and the SGWs, and performs relaying processing for the bearers between the HeNBs and the HeNB-GW and the bearers between the HeNB-GW and the SGWs. When the HeNB-GW 100 (control section H7) detects abnormality in the second network layer processing apparatus, based on the information on the occurrence of the failure, the HeNB-GW 100 (control section 137) instructs the second communication processing section 143 to perform disconnection processing of disconnecting the connection with the second network layer processing apparatus, i.e., processing of releasing the connection.

[0058]

(5) Examples

(5-1) Operation Example of Monitoring Connection State Related to MIME Next, an operation example of monitoring a connection state related to the MME will be described [0059] -Processing for Establishing Connection between HeNB-GW 100 and MMEs 311 and 312 Fig. 5 is a sequence diagram for illustrating processing for establishing connection between the HeNB-GW 100 and the MIVIEs 311 and 312. Fig. 6 is a specific example of an MME state management table 60. With reference to Fig. 5 and Fig. 6, the processing for establishing connection between the HeNB-GW 100 and the MMEs 311 and 312 will be described.

[0060] In the operation example illustrated in Fig. 5, the MME state management table 60 includes items of "IP address" being connection information and "state (status)" (normal or abnormal), concerning each of the MMEs 311 and 312. As an initial state, a value of an IP address and a value indication "abnormal" are set to each of the MMEs 311 and 312.

[0061] The HeNB-GW 100 (second communication processing section 133) reads the IP addresses of the MMEs 311 and 312 with reference to the MME state management table 60 (ST501), and transmits Si Setup Request to destinations (for example, the MMEs 311 and 312) by using the read IP addresses as the destinations (ST503). [0062] For example, when the HeNB-GW 100 (second communication processing section 133) receives a positive response (S1 Setup Response) returned from the MME 311 (ST505), the HeNB-GW 100 (second communication processing section 133) updates the state of the MME 311 in the MME state management table 60 to "normal" (ST507). On the other hand, for example, when the HeNB-GW 100 (second communication processing section 133) receives a negative response (SI Setup Failure) from the MME 312 or receives no responses (ST509), the HeNB-GW 100 (second communication processing section 133) updates the state of the MME 312 in the MIME state management table 60 to "abnormal-(ST511).

[0063] Next, the HeNB-GW 100 (second communication processing section 133) monitors normality of connection of the MIME 311 that returned Si Setup Response, through an SCTP Heartbeat procedure (ST513). When abnormality is detected through the procedure, or if the HeNB-GW 100 (second communication processing section 133) receives SCTP: Abort from the MME 311, the HeNB-GW 100 (second communication processing section 133) updates the state of the MIME 311 in the MME state management table to "abnormal" (ST515).

[0064] The HeNB-GW (second communication processing section 133) periodically transmits S1 Setup Request to the MME, 312, with which S1 connection is not established, to attempt an Si connection establishment (ST517). Subsequently, the processing of ST505 or ST509 is repeated.

[0065] -Processing for Establishing Connection between HeNB-GW 100 and HeNBs 211 and 212 Fig. 7 is a sequence diagram for illustrating processing for establishing connection between the HeNB-GW 100 and the HeNBs 211 and 212. Fig. 8 is a diagram illustrating a specific example of an HeNB-MME mapping table 80 stored in the storage section 120, for example. With reference to Fig. 7 and Fig. 8, the processing for establishing connection between the HeNB-GW 100 and the HeNBs 211 and 212 will be described.

[0066] First, the HeNB-GW 100 (first communication processing section 131) receives S1 Setup Request from any of the HeNBs 211 and 212 (ST701). Next, the HeNB-GW 100 (first communication processing section 131) determines an MME to be a connection destination, based on information elements of Si Setup Request (such as Global eNB ID/Supported TAs) and information preset in the HeNB-GW 100 (ST703). [0067] After the MATE to be a connection destination is determined, the HeNB-GW 100 (first communication processing section 131) accesses the MIME state management table to search for a state of the MME to be a connection destination (ST705). When the state of the MIME to be a connection destination is -normal", the HeNB-GW 100 (first communication processing section 131) returns a positive response (S1 Setup Response) to corresponding one of the HeNBs 211 and 212 (ST707). In this case, the HeNB-GW 100 (first communication processing section 131) stores information concerning which MMES are connected with the corresponding one of lleNBs 211 and 212, in the HeNB-MME mapping table 80 as illustrated in Fig. 8.

[0068] On the other hand, if the state of the MME to be a connection destination is "abnormal", the HeNB-GW 100 (first communication processing section 131) returns a negative response (St Setup Failure) to each of the HeNBs 211 and 212 (ST709), and transmits SCAT Abort (ST711). In this case, the HeNB-GW 100 (first communication processing section 131) sets "Transport Resource Unavailable" to CAUSE included in S1 Setup Failure, and notify corresponding one of the HeNBs 211 and 212 that transport resources are unavailable.

[0069] -Attach Sequence between HeNB and MME Fig. 9 is a diagram illustrating an Attach sequence performed after Si connections between the HeNBs 211 and 212 and the HeNB-GW 100 and St connections between the HeNB-GW 100 and the MMEs 311 and 312 are established. Fig. 10 is a diagram illustrating a specific example of a UE-bearer mapping table 10 stored in the storage section 120, for example. With reference to Fig. 9, the Attach sequence performed after S t connections between the HeNBs 211 and 212 and the HeNB-GW 100 and S1 connections between the HeNB-GW 100 and the MMEs 311 and 312 are established will be described.

[0070] First, any of the HeNBs receives Attach Request from the UE (ST901). The HeNB 211 or 212 includes received Attach Request in Si: Initial UE Message to transfer Attach Request to any of the MMEs 311 and 312, via the HeNB-GW 100 (ST903). Then, the MIME 311 or 312 transmit a session addition request (Create Session Request) to corresponding SGW 321 or 322 (ST905).

[0071] The SGW 321 or 322 transmit Create Session Response to corresponding MIME 311 or 312 (ST907), and the MIME 311 or 312 transmits Si: Initial Context Setup Request including Attach Accept to the HeNB-GW 100 (second communication processing section 133) (ST909).

[0072] The second communication processing section 133 notifies the control section 137 of bearer information (Bearer ID, SGW 1L1D, SGW IP) that is set in Initial Context Setup Request (ST911), and receives a positive response from the control section 137 (ST913). Subsequently, based on an MME UE S1 AP ID and an eNB UE S1 AP ID being LIE identification information that is set in Initial Context Setup Request, the second communication processing section 133 adds the bearer information on the bearer established for the UE (UE 400) to the UE-bearer mapping table 10 as illustrated in Fig. 10 (ST915). Subsequently, the HeNB-GW 100 transfers Sl: Initial Context Setup Request, in which the TEID/IP is replaced by an ID of the control section 137 of the HeNB-GW 100, to corresponding HeNB 211 or 212 (ST917). The HeNB-GW 100 (second communication processing section 133) notifies the control section 137 of an HeNB TEID and an HeNB IP that is set in Sl: E-RAB Setup Response being information necessary for relaying (ST919), and transfers Si: E-RAB Setup Response, in which the TEID/IP is replaced by the ID of the control section 137 of the HeNB-GW 100, to the corresponding MME 311 or 312 (ST921).

[0073] -Processing Performed when Abnormality Occurs in SI Connection between HeNB-GW and MME Fig. 11 is a diagram illustrating a sequence performed when S1 connections between the HeNB and the HeNB-GW and S1 connections between the HeNB-GW and the MME are established, and subsequently abnormality occurs in any of the S1 connections between the HeNB-GW and the MMES.

[0074] When the obtaining section 135 of the HeNB-GW 100 detects occurrence of abnormality in a connection with the MATE 311 (ST1101), the control section 137 of the HeNB-GW 100 notifies the first communication processing section 131 of an ID that specifies the MIME 311 relating to the failure (ST1103) The first communication processing section 131 refers to the HeNB-MME mapping table, based on the information of the MME ID, to create an ID/IP list of HeNBs that have been connected to the MME 311 (ST1105). Then, the first communication processing section 131 deletes corresponding entries of HeNB from the HeNB-MME mapping table (ST1107). The first communication processing section 131 transmits SCTP: Abort, which carries an intention of forcibly disconnecting SCTP connection, to the HeNBs 211 on the ID/IP list of the HeNBs that have been connected to the MME 311 (ST1109).

[0075] The second communication processing section 133 refers to the UE-bearer mapping table to search for a list of UEs (UE IDs) that have been connected to the MME (MME ID) related to the failure, as well as pieces of bearer information (number of bearers, bearer list, SGW IP) that have been established by the UEs (ST1 111), and transmits the list to the control section 137 (ST1113) Next, the second communication processing section 133 deletes corresponding entries of the UEs from the UE-bearer mapping table (ST1115). The control section 137 that has received the bearer list deletes information necessary for relaying, such as a TEID/IP (ST1117). [0076] (5-2) Operation Example of Monitoring Connection state of SGW Fig. 12 is a diagram for illustrating a specific example of a sequence performed when abnormality occurs in a connection in any of Sl-U interfaces between the HeNB-GW and the SGWs.

[0077] When the obtaining section 135 of the HeNB-GW 100 detects occurrence of abnormality in a connection with the SGW 321 (ST1201), the control section 137 of the HeNB-GW 100 performs processing of releasing E-RABs established with the SGW 321 in which the abnormality occurs (ST1203 and ST1205).

[0078] Subsequently, the second communication processing section 133 refers to the IIE-bearer mapping table to extract a list of UEs, no bearer information being stored corresponding to the UEs, and then creates an HeNB ID list of HeNBs serving to those UEs (ST1207), and notifies the first communication processing section 131 of the HeNB ID list (ST1209). Then, the first communication processing section 131 transmits SCTP: Abort, which carries an intention of forcibly disconnecting SCTP connection, to each of the HeNBs on the HeNB ID list (ST1211).

[0079] (5-3) Effects According to the examples, when abnormality is detected in a connection with an MIME, SCTP connection with an associated HeNB can be disconnected. As a result, the HeNB that loses the connection stops radio transmission, which allows UEs under the HeNB to transition to an available service provided by a macro cell, or a cell of another HeNB, for example.

[0080] According to the examples, an SCTP and 51 connection establishment request from an HeNB that attempts to establish connection with the MIME is rejected until connection between an HeNB-GW and the MME recovers. This configuration can prevent a TIE from entering a serving area of the same HeNB again.

[0081] According to the examples, when the HeNB-GW detects occurrence of abnormality in a connection with an MIME and thus disconnects a connection with an HeNB associated with the MME, the HeNB-GW can maintain a connection with another HeNB associated with an MIME in which no abnormality is detected. This configuration can prevent unnecessary radio transmission stoppage of an HeNB. [0082] According to the examples, also when abnormality is detected in a connection with the HeNB-GW and an SGW, a SCTP connection with an HeNB associated with the SGW is disconnected. This configuration can prevent a UE from immediately repeating an Attach procedure.

[0083] <2.4. Example Alterations> In the above-described examples, each MME is a single apparatus; however, a connection of MIVIE POOL constituted with a plurality of MMEs may be a monitoring target, based on application of the SI-Flex technology, for example. In this case, if it is determined that all the MMEs in the MIME Pool connected with an HeNB have connection abnormality, the HeNB-GW may disconnect an SCTP and S1 connection with the HeNB. Then, when connection with even one of the MMEs in the MME Pool recovers, the HeNB-GW may recognize that the state thereof has changed to the "normal" state, and may accept a connection request transmitted from the HeNB to the MIME Pool.

[0084] <<3. Second Example Embodiment>> Next, with reference to Fig. 13 and Fig. 14, a second example embodiment of the present invention will be described.

[0085] <3.1. System Configuration> With reference to Fig. 13, an example of a configuration of a system 2 according to the second example embodiment of the present invention will be described. Fig. 13 is an explanatory diagram illustrating an example of a schematic configuration of the system 2 according to the second example embodiment of the present invention. With reference to Fig. 13, the system 2 includes a central unit 500 (CU), distributed units 611 and 612 (DUs), core network nodes 701 and 702, and a UE 800.

[0086] Specifically, the system 2 employs architecture of the 5G communication systems. In the system 2, each of the core network nodes 701 and 702 is connected to the CU 500 being a central node, via a New Generation (NG) interface. Further, each of the DUs 611 and 612, which communicates with the UE 800 via a radio interface, and the CU 500 are connected to each other via an F1 interface.

[0087] <3.2. Configuration of CU 500> Next, with reference to Fig. 14, an example of a configuration of the CU 500 according to the second example embodiment will be described. Fig. 14 is a block diagram illustrating an example of a schematic configuration of the CU 500 according to the second example embodiment. With reference to Fig. 14, the CU 500 includes a network communication section 510, a storage section 520, and a processing section 530.

[0088] (1) Network Communication Section 510 The network communication section 510 receives signals from a network, and transmits signals to the network.

[0089] (2) Storage Section 520 The storage section 520 temporarily or permanently stores programs (instructions) and parameters for operation of the CU 500, as well as various data. The program includes one or more instructions for operation of the CU 500.

[0090] (3) Processing Section 530 The processing section 530 provides various functions of the CU 500 The processing section 530 includes a first communication processing section 531, a second communication processing section 533, an obtaining section 535, and a control section 537. Note that the processing section 530 may further include constituent elements other than these constituent elements. In other words, the processing section 530 may also perform operation other than the operation of these constituent elements. Specific operation of the first communication processing section 531, the second communication processing section 533, the obtaining section 535, and the control section 537 will be described later in detail.

[0091] (4) Implementation Example The network communication section 510 may be implemented with a network adapter and/or a network interface card, and the like. The storage section 520 may be implemented with a memory (e.g., a nonvolatile memory and/or a volatile memory) and/or a hard disk, and the like. The processing section 530 may be implemented with one or more processors. The first communication processing section 531, the second communication processing section 533, the obtaining section 535, and the control section 537 may be implemented with the same processor, or may be separately implemented with different processors. The memory (storage section 520) may be included in the one or more processors or may be provided outside the one or more processors.

[0092] The CU 500 may include a memory configured to store a program (instructions) and one or more processors that can execute the program (instructions). The one or more processors may execute the program, and thereby perform operation of the processing section 530 (operation of the first communication processing section 531, the second communication processing section 533, the obtaining section 535, and/or the control section 537). The program may be a program for causing the processor(s) to execute operation of the processing section 530 (operation of the first communication processing section 531, the second communication processing section 533, the obtaining section 535, and/or the control section 537).

[0093] <3.3. Technical Features> Next, technical features of the second example embodiment will be described.

The CU 500 (first communication processing section 531) communicates with one or more first network layer processing apparatuses which perform processing of a first network layer. The CU 500 (second communication processing section 533) communicates with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer. The CU 500 (obtaining section 535) obtains information on occurrence of failure in connection with the second network layer processing apparatus. The CU 500 (control section 537) specifies a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on the occurrence of the failure.

[0094] For example, the first network layer processing apparatuses first units of a radio access network, such as the DUs 611 and 612. Specifically, the CU 500 is a second unit of the radio access network which accommodates the first units such as the DUs 611 and 612. For example, the second network layer processing apparatuses are core network nodes, such as the core network nodes 701 and 702.

[0095] The CU 500 (obtaining section 535) may detect the occurrence of the failure in the connection with the second network layer processing apparatus, to obtain the information on the occurrence of the failure in the connection.

[0096] More specifically, the CU 500 (second communication processing section 533) may update, in accordance with a connection state with the second network layer processing apparatus, a state management table which stores information on the connection state in the storage section 520, for example. Further, the CU 500 (obtaining section 535) may detect the occurrence of the failure in the connection with the second network layer processing apparatus, to obtain the information on the occurrence of the failure in the connection with reference to the state management table. [0097] According to the second example embodiment, the CU 500 that has detected a connection abnormality with any of the core network nodes 701 and 702 can disconnect a connection with DUs which communicate with the corresponding core network node, and can reject a reconnection request from the DUs until the core network nodes recover.

[0098] <<4. Third Example Embodiment>> Next, with reference to Fig. 15, a third example embodiment of the present invention will be described. The above-described first and second example embodiments are each a concrete example embodiment, whereas the third example embodiment is a more generalized example embodiment.

[0099] <4.1. Configuration of Communication Apparatus 1000> First, with reference to Fig. 15, an example of a configuration of a communication apparatus 1000 according to the third example embodiment w 11 be described. Fig. 15 is a block diagram illustrating an example of a schematic configuration of the communication apparatus 1000 according to the third example embodiment. With reference to Fig. 15, the communication apparatus 1000 includes a first communication processing section 1031, a second communication processing section 1033, an obtaining section 1035, and a control section 1037. Specific operation of the first communication processing section 1031, the second communication processing section 1033, the obtaining section 1035, and the control section 1037 will be described later.

[0100] The first communication processing section 1031, the second communication processing section 1033, the obtaining section 1035, and the control section 1037 may be implemented with the same processor, or may be separately implemented with different processors. The first communication processing section 1031, the second communication processing section 1033, the obtaining section 1035, and the control section 1037 may include a memory configured to store a program (instructions) and one or more processors that can execute the program (instructions), and the one or more processors may perform operation of the first communication processing section 1031, the second communication processing section 1033, the obtaining section 1035, and the control section 1037. The program may be a program for causing the processor(s) to perform the operations of the first communication processing section 1031, the second communication processing section 1033, the obtaining section 1035, and the control section 1037.

[0101] Note that each of the above-described processors may, for example, be a virtual processor implemented with a hypervisor installed in a general-purpose computer or the like. Moreover, the above-described memory or memories may, for example, be a virtual memory implemented with a hypervisor installed in a general-purpose computer or the like.

[0102] <4.2. Technical Features> Next, technical features of the third example embodiment will be described.

[0103] In the third example embodiment, the communication apparatus 1000 (first communication processing section 1031) communicates with one or more first network layer processing apparatuses which perform processing of a first network layer. The communication apparatus 1000 (second communication processing section 1033) communicates with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer. The communication apparatus 1000 (obtaining section 1035) obtains information on occurrence of failure in connection with the second network layer processing apparatus. The communication apparatus 1000 (control section 1037) specifies a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on the occurrence of the failure. [0104] For example, the first communication processing section 1031 may perform operation of the first communication processing section 131 according to the above-described first example embodiment or the first communication processing section 531 according to the above-described second example embodiment. The second communication processing section 1033 may perform operation of the second communication processing section 133 according to the above-described first example embodiment or the second communication processing section 533 according to the above-described second example embodiment. The obtaining section 1035 may perform operation of the obtaining section 135 according to above-described first example embodiment or the obtaining section 535 according to the above-described second example embodiment. The control section 1037 may perform operation of the control section 137 according to the above-described first example embodiment or the control section 137 according to the above-described second example embodiment. [0105] The third example embodiment has been described above. According to the third example embodiment, for example, appropriate control over operation of the first network layer processing apparatus which performs processing of the first network layer is enabled, even when failure occurs in the second network layer processing apparatus which performs processing of the second network layer which is higher than the first network layer.

[0106] <<5. Terminal Apparatus>> In the first to third example embodiments, the terminal apparatus is a user terminal (User Equipment, UE) (or including a mobile station, a mobile terminal, a mobile device, a wireless device, or the like) as described below.

[0107] First, the user terminal (User Equipment, UE) (or including a mobile station, a mobile terminal, a mobile device, a wireless device, or the like) is an entity connected to a network via a radio interface.

[0108] The UE in the Specification is not limited to a dedicated communication apparatus, and may be any device as described below that includes communication functions of the UE described in the Specification.

[0109] Each of "user terminal (User Equipment, UE) as an expression used in the 3rd Generation Partnership Project (3GPP)", "mobile station", "mobile terminal", "mobile device", and "wireless terminal" used as a term is intended to have the same meaning as each other in general, and may be a stand-alone mobile station, such as a terminal, a mobile phone, a smartphone, a tablet, a cellular IoT terminal, and an IoT device. [0110] Note that it should be understood that "UE" and "wireless terminal-used as a term also encompass an apparatus that remains fixed for a long period of time.

[0111] Further, for example, the UE may be a production facility, a manufacturing facility, and/or an energy-related machine (examples thereof include a boiler, an engine, a turbine, a solar panel, a wind power generator, a hydroelectric power plant, a thermal power plant, a nuclear power plant, a storage battery, a nuclear power system, a nuclear-related device, a heavy electric device, a pump such as a vacuum pump, a compressor, a fan, an air blower, a hydraulic device, an pneumatic device, a metal processing machine, a manipulator, a robot, a robot application system, a tool, a die, a roll, a conveyance apparatus, an elevating apparatus, a freight handling apparatus, a fiber-related machine, a sewing machine, a printing machine, a print-related machine, a paper processing machine, a chemical machine, a mining machine, a mining-related machine, a construction machine, a construction-related machine, an agricultural machine and/or instrument, a forestry machine and/or instrument, a fishery machine and/or instrument, a safety and/or environment preservation instrument, a tractor, a bearing, a precision bearing, a chain, a gear, a power transmission apparatus, a lubrication apparatus, a valve, a pipe joint, and/or an application system for any device or machine described above).

[0112] Further, for example, the UE may be a transport apparatus (examples thereof include a vehicle, an automobile, a two-wheeled vehicle, a bicycle, a train, a bus, a vehicle-drawn cart, a rickshaw, a ship and other watercraft, an airplane, a rocket, an artificial satellite, a drone, and a hot-air balloon).

[0113] Further, for example, the UE may be an information communication apparatus (examples thereof include an electronic computer and its related apparatus, a communication apparatus and its related apparatus, and an electronic component). [0114] Further, for example, the UE may be a refrigerator, a refrigerator application appliance and apparatus, a commercial and service device, a vending machine, an automated service machine, a machine and an apparatus for an office, and a consumer electric and electronic machine instrument (examples thereof include an audio device, a speaker, a radio, an image/video display device, a television, a microwave oven, a rice cooker, a coffee maker, a dishwashing machine, a laundry machine, a drying machine, a fan, an exhaust fan and its related appliance, and a vacuum cleaner).

[0115] Further, for example, the UE may be an electronic application system or an electronic application apparatus (examples thereof include an X-ray apparatus, a particle acceleration apparatus, a radioactive substance application apparatus, a sonic wave application apparatus, an electromagnetic application apparatus, and an electric power application apparatus).

[0116] Further, for example, the UE may be a light bulb, a lighting device, a metering machine, an analyzing device, a testing and measuring machine (examples thereof include a smoke alarm device, a human alarm sensor, a motion sensor, and a wireless tag), a watch or a clock, a physical and chemical machine, an optical machine, a medical device and/or a medical system, a weapon, a sharp-edged craft tool, or a hand tool.

[0117] Further, for example, the UE may be a personal digital assistant or apparatus provided with radio communication functions (examples thereof include an electronic apparatus configured to allow attachment or insertion of a wireless card, a wireless module, and the like (for example, a personal computer and an electronic measuring device)).

[0118] Further, for example, the UE may be an apparatus, or a part of the apparatus, that provides an application, a service, and a solution as described below, in "Internet of Everything (Internet of Things (IoT))" using wired or wireless communication technologies.

[0119] An IoT device (or thing) includes an appropriate electronic device, software, sensor, and network connection, for example, that enable data collection and data exchange between devices, or with another communication device.

[0120] Further, the IoT device may be an automated device that follows software instructions stored in internal memory.

[0121] Further, the IoT device may operate without the need of human directions or control. [0122] Further, the loT device may be an apparatus installed for a long period of time, and/or may remain inactive for a long period of time.

[0123] Further, the IoT device may be implemented as a part of a stationary apparatus. The loT device may be embedded in a non-stationary apparatus (for example, a vehicle), or may be attached to an animal or a human being to be monitored/tracked.

[0124] It should be understood that the IoT technology can be implemented in any communication device that can connect to a communication network allowing transmission and/or reception of data, irrespective of human input control or software instructions stored in memory.

[0125] It should be understood that the IoT device may be referred to as a Machine Type Communication (MTC) device, a Machine to Machine (M2M) communication device, or a Narrow Band-IoT (NB-IoT) UE.

[0126] Further, it should be understood that the UE can support one or more applications of IoT or MTC applications.

[0127] Fig. 16 is a diagram illustrating some examples of MTC applications. Specifically, some examples of MTC applications are listed in a table disclosed in Annex B of Ref 1 below (contents of which are incorporated herein by reference), as illustrated in Fig. 16, for example.

Ref 1: 3GPP TS 22.368 V13.2.0 (Upload date: 2017-01-13) The list is not comprehensive, and indicates only some examples of MTC applications.

[0128] Some examples of the application, the service, and the solution may include a Mobile Virtual Network Operator (NIVNO) service/system, a disaster prevention radio service/system, a private radio telephone (Private Branch Exchange (PBX)) service/system, a PHS/digital cordless telephone service/system, a Point of Sale (POS) system, an advertising service/system, a multicast (Multimedia Broadcast and Multicast Service (MBMS)) service/system, a Vehicle to Everything (V2X) (vehicle-to-vehicle communication, vehicle-to-infrastructure communication, and vehicle-to-pedestrian communication) service/system, an in-train mobile radio service/system, a positional information-related service/system, a radio communication service/system in case of a disaster/emergency, an Internet of Things (IoT) service/system, a community service/system, an image/video distribution service/system, a femtocell application service/system, a Voice over LTE (VoLTE) service/system, a wireless tag service/system, a billing service/system, a radio on-demand service/system, a roaming service/system, a user behavior monitoring service/system, a communication carrier/communication NW selection service/system, a function limitation service/system, a Proof of Concept (PoC) service/system, a personal information management service/system for a terminal, a display image/video service/system for a terminal, a non-communication service/system for a terminal, and an ad hoc NW/Delay Tolerant Networking (DTN) service/system.

[0129] Note that the above-described UE categories are merely application examples of the technical concept and the example embodiments described in the Specification. It goes without saying that these examples are not restrictive, and those of ordinary skill in the art can make various modifications.

[0130] <<6. Other Aspects>> Descriptions have been given above of the example embodiments of the present invention. However, the present invention is not limited to these example embodiments. It should be understood by those of ordinary skill in the art that these example embodiments are merely examples and that various alterations are possible without departing from the scope and the spirit of the present invention.

[0131] For example, the steps of the processing described in the Specification may not be necessarily executed in time series along the order illustrated in the sequence diagrams. For example, the steps of the processing may be executed in order different from the order described in the sequence diagrams, or may be executed in parallel. A part of the steps of the processing may be omitted, and another step may be added in the processing.

[0132] Moreover, an apparatus including constituent elements (e.g., the first communication processing section, the second communication processing section, the obtaining section, and/or the control section) of the communication apparatus described in the Specification (e.g., one or more apparatuses (or units) among a plurality of apparatuses (or units) constituting the communication apparatus, or a module for one of the plurality of apparatuses (or units)) may be provided. Moreover, methods including processing of the constituent elements may be provided, and programs for causing a processor to execute processing of the constituent elements may be provided.

Moreover, non-transitory computer-readable recording media (non-transitory computer readable media) having recorded thereon the programs may be provided. It is apparent that such apparatuses, modules, methods, programs, and non-transitory computer-readable recording media are also included in the present invention.

[0133] The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes.

[0134] (Supplementary Note 1) A communication apparatus comprising: a first communication processing section configured to communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; a second communication processing section configured to communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; an obtaining section configured to obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and a control section configured to specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0135] (Supplementary Note 2) The communication apparatus according to Supplementary Note 1, wherein at least one of the one or more first network layer processing apparatuses is a femtocell base station.

[0136] (Supplementary Note 3) The communication apparatus according to Supplementary Note 2, wherein the communication apparatus is a gateway which accommodates one or more femtocell base stations including the femtocell base station.

[0137] (Supplementary Note 4) The communication apparatus according to Supplementary Note 1, wherein the one or more first network layer processing apparatuses are one or more first units of a radio access network.

[0138] (Supplementary Note 5) The communication apparatus according to Supplementary Note 4, wherein the communication apparatus is a second unit of the radio access network which accommodates the one or more first units.

[0139] (Supplementary Note 6) The communication apparatus according to any one of Supplementary Notes 2 to 5, wherein the one or more second network layer processing apparatuses are one or more core network nodes.

[0140] (Supplementary Note 7) The communication apparatus according to any one of Supplementary Notes 1 to 6, wherein the obtaining section is configured to obtain the information on occurrence of the failure in the connection, by detecting occurrence of the failure in the connection with the at least one second network layer processing apparatus.

[0141] (Supplementary Note 8) The communication apparatus according to Supplementary Note 7, wherein the second communication processing section is configured to update, in accordance with a connection state with each of the one or more second network layer processing apparatuses, a state management table which stores information on the connection state; and the obtaining section is configured to obtain the information on occurrence of the failure in the connection, by detecting occurrence of the failure in the connection with the at least one second network layer processing apparatus with reference to the state management table.

[0142] (Supplementary Note 9) A communication method comprising: communicating with one or more first network layer processing apparatuses which perform processing of a first network layer; communicating with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtaining information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specifying, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0143] (Supplementary Note 10) A program that causes a processor to: communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0144] (Supplementary Note 11) A computer-readable non-transitory recording medium having recorded thereon a program that causes a processor to: communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.

[0145] This application claims priority based on Japanese Patent Application No. 2019-044548 filed on March 12, 2019, the entire disclosure of which is incorporated herein.

[0146] In mobile communication systems, appropriate control over operation of the first network layer processing apparatus which performs processing of the first network layer is enabled, even when failure occurs in the second network layer processing apparatus which performs processing of the second network layer which is higher than the first network layer.

Claims

WHAT IS CLAIMED IS: 1 A communication apparatus comprising: a first communication processing section configured to communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; a second communication processing section configured to communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; an obtaining section configured to obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and a control section configured to specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.
2. The communication apparatus according to claim I, wherein at least one of the one or more first network layer processing apparatuses is a femtocell base station.
3. The communication apparatus according to claim 2, wherein the communication apparatus is a gateway which accommodates one or more femtocell base stations including the femtocell base station.
4. The communication apparatus according to claim 1, wherein the one or more first network layer processing apparatuses are one or more first units of a radio access network.
5. The communication apparatus according to claim 4, wherein the communication apparatus is a second unit of the radio access network which accommodates the one or more first units.
6. The communication apparatus according to any one of claims 2 to 5, wherein the one or more second network layer processing apparatuses are one or more core network nodes.
7. The communication apparatus according to any one of claims 1 to 6, wherein the obtaining section is configured to obtain the information on occurrence of the failure in the connection, by detecting occurrence of the failure in the connection with the at least one second network layer processing apparatus.
8. The communication apparatus according to claim 7, wherein the second communication processing section is configured to update, in accordance with a connection state with each of the one or more second network layer processing apparatuses, a state management table which stores information on the connection state; and the obtaining section is configured to obtain the information on occurrence of the failure in the connection, by detecting occurrence of the failure in the connection with the at least one second network layer processing apparatus with reference to the state management table.
9. A communication method comprising: communicating with one or more first network layer processing apparatuses which perform processing of a first network layer; communicating with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtaining information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specifying, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.
10. A program that causes a processor to: communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.
11. A computer-readable non-transitory recording medium having recorded thereon a program that causes a processor to: communicate with one or more first network layer processing apparatuses which perform processing of a first network layer; communicate with one or more second network layer processing apparatuses which perform processing of a second network layer which is higher than the first network layer; obtain information on occurrence of failure in connection with at least one second network layer processing apparatus among the one or more second network layer processing apparatuses; and specify, among the one or more first network layer processing apparatuses, a first network layer processing apparatus whose connection is set up with the second network layer processing apparatus in which the failure has occurred, to disconnect the connection, based on the information on occurrence of the failure.