Communication device, communication system, control circuit, storage medium, and communication method

Abstract

A communication device (40) is used in a communication system that operates as a virtually time-sensitive switch, and comprises: a bridge management unit (401) that uses a first service quality requested for a communication system to configure network nodes, which are included in a wired connection section among network nodes in a traffic communication path, according to a second service quality requested for the wired connection section; a pseudo bridge management unit (403) that configures network nodes included in a wireless connection section according to a third service quality requested for the wireless connection section on the basis of a difference between the first service quality and the second service quality; a log information collection unit (402) that acquires log information indicating a communication state from the network nodes; and an abnormal location estimation unit (406) that estimates, on the basis of the log information, an inter-network-node path or network node that does not satisfy the second service quality or the third service quality.

Description

COMMUNICATION DEVICE, COMMUNICATION SYSTEM, CONTROL CIRCUIT, STORAGE MEDIUM, AND COMMUNICATION METHOD

[0001] The present disclosure relates to a communication device, a communication system, a control circuit, a storage medium, and a communication method used in a communication system.

[0002] In Release 16, the 3GPP (registered trademark) (3rd Generation Partnership Project) standardized support for TSN TSC (TSN Time Sensitive Communication), a function that treats the 5G system as a virtual bridge and transfers Ethernet communications between control devices located on a TSN (Time Sensitive Networking) domain outside the 5G system via the 5G system. Since TSN is an Ethernet-based technology, the PDU (Protocol Data Unit) type transferred in the 5G system by the TSN TSC is limited to the Ethernet type.

[0003] In addition, Release 17 standardizes support for non-TSN network domains, which is a function for transferring Ethernet communication or IP (Internet Protocol) communication between control devices of one or more non-TSN network domains located in a terminal equivalent to a control device or a network under the terminal and control devices located in a non-TSN network domain outside the 5G system via the 5G system. The non-TSN TSC supports both Ethernet type and IP type as PDU types.

[0004] In addition, Release 18 also standardized the introduction of the TSN mechanism into the transport network, which serves as the transfer path between wireless communication base stations and the core network, in order to realize time-sensitive communications.

[0005] When providing TSC, the 5G system operates as a virtual time-sensitive switch from the perspective of an external network domain. When the 5G system operates as a virtual time-sensitive switch using the TSC function from the perspective of an external network, the external network sets the end-to-end (hereinafter referred to as E2E) quality of service (hereinafter referred to as QoS) in the external network domain for the 5G system. The 5G system sets user data transfer paths in wireless communication sections and wired communication sections within the 5G system so as to satisfy the set QoS. For example, Patent Document 1 discloses a technology that generates schedule information for transfer paths in wired sections based on wireless-side scheduling results, particularly at a distributed base station within the 5G system, for the required QoS, thereby enabling appropriate transfer scheduling for the transfer paths in the wired sections.

[0006] International Publication No. 2022 / 162920

[0007] When a 5G system operates as a virtual time-sensitive switch, the application realized by the external network is time-sensitive communication, such as control communication between control devices in a factory. Therefore, if the 5G system cannot achieve the required QoS, the application may stop, and as a condition for restarting the application, it may be necessary to investigate the cause of the failure to achieve the required QoS and take permanent measures. However, when communication that does not meet the QoS required by E2E occurs instantaneously due to changes in communication quality, such as changes in the wireless communication environment, the above-mentioned conventional technology has a problem in that it is difficult to estimate which communication path or which device constituting the communication path is the bottleneck among the communication paths constituting the virtual time-sensitive link, simply by scheduling for each transfer path.

[0008] The present disclosure has been made in consideration of the above, and aims to provide a communication device that can detect communications that do not meet the service quality required in a communication system that operates as a virtual time-sensitive switch, and estimate the device or route that is causing the problem.

[0009] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a communication device used in a communication system that operates as a virtually time-sensitive switch, the communication device comprising: a bridge management unit that performs configurations for network nodes in a wired connection section among network nodes that form a communication path for traffic in the communication system according to a second quality of service required in the wired connection section based on a first quality of service required for the communication system; a pseudo-bridge management unit that performs configurations for network nodes in a wireless connection section among the network nodes according to a third quality of service required in the wireless connection section based on a difference between the first quality of service and the second quality of service; a log information collection unit that acquires log information from the network nodes that indicates a communication state when the network nodes transmit and receive traffic; and an anomaly location estimation unit that estimates, based on the log information, network nodes or paths between network nodes that do not satisfy the second quality of service or the third quality of service.

[0010] The communication device according to the present disclosure has the effect of being able to detect communications that do not satisfy the quality of service required in a communication system that operates virtually as a time-sensitive switch, and to estimate the device or route causing the problem.

[0011] 1 is a diagram showing an example of the configuration of a communication network according to an embodiment;

[0023] FIG. 1 is a block diagram showing an example of the configuration of a wireless communication terminal according to an embodiment;

[0024] FIG. 1 is a block diagram showing an example of the configuration of a wireless communication base station according to an embodiment;

[0025] FIG. 1 is a block diagram showing an example of the configuration of a core network device according to an embodiment;

[0026] FIG. 1 is a block diagram showing an example of the configuration of a communication device according to an embodiment;

[0027] FIG. 1 is a block diagram showing an example of the configuration of a transport network device constituting a transport network according to an embodiment;

[0028] FIG. 2 is a diagram showing one-way communication traffic when a communication system according to an embodiment is operated as a virtual TSN switch;

[0029] FIG. 2 is a diagram showing time-sensitive time-division scheduling for one-way communication traffic when a communication system according to an embodiment is operated as a virtual TSN switch;

[0029] FIG. 3 is a sequence diagram showing an example of operation up to the start of traffic measurement triggered by power-on of a wireless communication terminal in a communication system according to an embodiment;

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A communication device, a communication system, a control circuit, a storage medium, and a communication method according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0013] Embodiment. FIG. 1 illustrates an example configuration of a communication network 80 according to this embodiment. The communication network 80 includes a communication system 1, multiple TSNs 2, and a CUC (Centralized Unit Configurator) / CNC (Centralized Network Configurator) 60. The communication network 80 is a time-sensitive network that virtually operates the communication system 1 as a time-sensitive switch. The time-sensitive network here refers to a network that is controlled by wired transfer scheduling after achieving highly accurate time synchronization. A time-sensitive network generally realizes transfer times with a deterministic amount of delay and delay fluctuation for traffic that occurs periodically from a source device to a logically connected destination device. A time-sensitive switch is used in such a time-sensitive network and can ensure real-time performance with guaranteed time synchronization. In this embodiment, a case where the communication system 1 is configured as a virtual TSN switch will be described.

[0014] The communication system 1 includes one or more wireless communication terminals 10, one or more wireless communication base stations 20, a core network device 30 serving as a gateway device connecting to an external network, a transport network 3, and a communication device 40. The communication system 1 provides a virtual TSN communication link for applications between control devices 50 located on multiple TSNs 2 deployed at different locations by wirelessly bridging a TSN 2 that is also deployed under the wireless communication terminal 10 as an external network. To function as a virtual TSN switch, the communication system 1 has a wired interface with the TSN 2 and provides the wireless communication terminal 10 and the core network device 30 as virtual TSN ports. In the communication system 1, the wireless communication terminal 10, the wireless communication base station 20, the core network device 30, and the transport network 3 are network nodes that serve as communication paths for traffic and report log information indicating the communication status when transmitting and receiving traffic to the communication device 40, as described below.

[0015] The transport network 3 is a group of network devices that physically connects the wireless communication base station 20 and the core network device 30 in order to provide a logical connection between the wireless communication base station 20 and the core network device 30 in the communication system 1. The transport network 3 synchronizes with the time of the communication system 1 with high precision and performs wired transfer according to the transfer scheduling set by the communication device 40. The transport network 3 also monitors whether traffic is being received according to the transfer scheduling set by the communication device 40. If the wireless communication base station 20 and the core network device 30 can be physically connected, the communication system 1 can also logically connect the wireless communication base station 20 and the core network device 30 without going through the transport network 3. Note that in this embodiment, the communication system 1 will be described assuming a Layer 2 bridge system.

[0016] The control devices 50 are devices that exist on the TSN2. The control devices 50 exchange communications between themselves to control, for example, machine tools in a factory. The applications used by the control devices 50 are broadly classified into periodic and non-periodic applications, which are set according to the requirements of the application. Furthermore, to perform highly accurate time synchronization for periodic communications, the communication traffic for time synchronization also has a periodic nature.

[0017] The CUC / CNC 60 performs settings for the TSN 2 and the communication system 1 to operate as a TSN switch. As shown in Fig. 1, for the communication system 1, the CUC / CNC 60 performs settings for the core network device 30 included in the communication system 1. The CUC / CNC 60 also performs settings for the control device 50 to operate as a TSN end station.

[0018] The wireless communication terminal 10 functions as a mobile terminal in the communication system 1. The wireless communication terminal 10 has a wireless interface with the wireless communication base station 20 and a wired interface as a TSN port. The wireless communication terminal 10 simultaneously holds the time of the communication system 1 and the time of TSN2 in order to establish the communication system 1 as a TSN bridge. The wireless communication terminal 10 also transfers application traffic of the control device 50 received via the wireless interface to the wired interface, and transfers application traffic of the control device 50 received via the wired interface to the wireless interface. The wireless communication terminal 10 also measures whether the application traffic addressed to the control device 50 and transferred from the TSN port satisfies the required QoS.

[0019] The wireless communication base station 20 performs wireless communication with the wireless communication terminal 10 via a wireless interface. The wireless communication base station 20 also transfers, via wireless communication, application traffic of the control device 50 received via the wired interface to the wireless communication terminal 10 that is the TSN port where the destination control device 50 is located. The wireless communication base station 20 also transfers the application traffic of the control device 50 received via the wireless interface to the wired interface, with the core network device 30 set as the transfer path as the destination.

[0020] The core network device 30 controls the communication system 1. Here, the control of the communication system 1 includes radio access management, mobility management, subscriber information management, session management, slice management, policy charging management, and control of the wireless communication base station 20 for the wireless communication terminal 10. The core network device 30 also simultaneously holds the time of the communication system 1 and the time of TSN2 in order to establish the communication system 1 as a TSN bridge. The core network device 30 also has a TSN port when the communication system 1 is a TSN bridge, and forwards application traffic of the control device 50 received at the TSN port to the wireless communication base station 20, which is the forwarding path to the wireless communication terminal 10, which is the appropriate forwarding destination TSN port, via the transport network 3. The core network device 30 also forwards the application traffic of the control device 50, which has been forwarded from the wireless communication base station 20 via the transport network 3 and wirelessly transmitted by the wireless communication terminal 10, to the TSN2 connected to the TSN port of the wireless communication terminal 10 or the core network device 30, which is the appropriate forwarding destination TSN port. Furthermore, the core network device 30 measures whether the application traffic destined for the control device 50 and forwarded from the TSN port satisfies the requested QoS.

[0021] The communication device 40 configures the transport network 3 to operate as a time-sensitive network, and configures the core network device 30 and the wireless communication base station 20 to operate as end stations in the time-sensitive network. At this time, the core network device 30 calculates setting values ​​by utilizing QoS parameter settings requested by the CUC / CNC 60 to operate as a virtual TSN switch. The communication device 40 is a device used in the communication system 1 that operates as a virtual time-sensitive switch.

[0022] 1, the communication system 1 includes two wireless communication terminals 10, but it is also possible to include three or more wireless communication terminals 10. Also, in the example of Fig. 1, the core network device 30 has two wired-connected TSNs 2, but it is also possible to have three or more wired-connected TSNs 2. Also, in the example of Fig. 1, there is one control device 50 on each TSN 2, but it is also possible to have two or more control devices 50 on each TSN 2.

[0023] 2 is a block diagram showing an example of the configuration of wireless communication terminal 10 according to the present embodiment. Wireless communication terminal 10 includes log information collection unit 101, traffic estimation unit 102, wireless communication unit 103, memory control unit 104, wired communication unit 105, traffic measurement unit 106, log information reporting unit 107, memory 108, wired NIC (Network Interface Card) unit 109, and antenna unit 110. Wired NIC unit 109 is configured to be wired connected to TSN 2 in FIG. 1. Antenna unit 110 is configured to transmit and receive wireless signals to and from wireless communication base station 20 in FIG. 1. Although FIGS. 1 and 2 show wired NIC unit 109 and antenna unit 110 as being external to wireless communication terminal 10, in reality, wired NIC unit 109 and antenna unit 110 are also included as part of the configuration of wireless communication terminal 10.

[0024] The log information collection unit 101 periodically measures log information such as wireless communication quality, such as received signal power strength at the wireless interface, headers and timestamps of control device application traffic passing through the wired interface, and device loads, such as CPU (Central Processing Unit) usage and temperature, of the wireless communication terminal 10. The log information collection unit 101 stores the measured log information in the memory 108.

[0025] The traffic estimation unit 102 estimates when the next periodic control device application traffic will pass among the control device application traffic transferred between the wireless communication unit 103 and the wired communication unit 105. The periodic control device application traffic referred to here is set from header information, etc. For example, since the time slots for each priority are determined according to the cyclic period and priority queue from the TSN scheduling table managed by the wired communication unit 105, the traffic estimation unit 102 can estimate the next passage time by calculating the return time of the control device application traffic periodically input from TSN2 over a certain period of time.

[0026] The wireless communication unit 103 has a wireless interface function that performs transmission and reception processing of wireless signals input and output from the antenna unit 110. The wireless communication unit 103 also receives control from the core network device 30. The wireless communication unit 103 also has a modem function that performs wireless protocol processing such as control signal transmission and user data transmission with the wireless communication base station 20. The wireless communication unit 103 also restores the time of the communication system 1 from the wireless interface and manages the time as part of the communication system 1. The wireless communication unit 103 also transfers control device application traffic received wirelessly to the wired communication unit 105. The wireless communication unit 103 also wirelessly transmits the control device application traffic transferred from the wired communication unit 105.

[0027] The memory control unit 104 discards from the memory 108 any log information accumulated by the log information collection unit 101 that is older than a certain period of time. The certain period of time is, for example, a period specified by a user of the communication system 1. The memory control unit 104 also discards from the memory 108 any log information that has already been reported to the communication device 40 by the log information reporting unit 107.

[0028] The wired communication unit 105 has a wired interface function for processing wired signals input and output by the wired NIC unit 109. The wired communication unit 105 also has a forwarding function for transmitting control device application traffic transferred from the wireless communication unit 103 to an appropriate TSN2 via the connected wired NIC unit 109 at appropriate timing according to a cyclic period and a priority queue from a TSN scheduling table set by the core network device 30, and for receiving the control device application traffic via a wired connection from the wired NIC unit 109. The wired communication unit 105 also has a time synchronization function as part of the TSN2, a priority control function as part of the TSN2, and a time stamping and time synchronization packet correction function for establishing the communication system 1 as a bridge.

[0029] The traffic measurement unit 106 measures the passage time of the control device application traffic transferred from the wireless communication unit 103 to the wired communication unit 105. The traffic measurement unit 106 also measures the passage time of the control device application traffic transferred from the wired communication unit 105 to the wireless communication unit 103.

[0030] The log information reporting unit 107 transfers the log information accumulated in the memory 108 to the wireless communication unit 103 for transmission to the communication device 40 when the log information is received at a timing other than the reporting period or the timing expected by the traffic measurement unit 106, or in accordance with instructions from the communication device 40.

[0031] The memory 108 stores setting information such as parameters for operating the wireless communication terminal 10, and accumulates log information.

[0032] The wired NIC unit 109 transmits the signal input from the wired communication unit 105 to the connected TSN 2 via a wired connection. The wired NIC unit 109 also outputs the signal received via a wired connection from the TSN 2 to the wired communication unit 105.

[0033] The antenna unit 110 converts the signal input from the wireless communication unit 103 into radio waves and transmits the radio waves. The antenna unit 110 also outputs the received signal to the wireless communication unit 103.

[0034] 3 is a block diagram showing an example of the configuration of the wireless communication base station 20 according to this embodiment. The wireless communication base station 20 includes a log information collection unit 201, a traffic estimation unit 202, a wireless communication unit 203, a memory control unit 204, a wired communication unit 205, a traffic measurement unit 206, a log information reporting unit 207, a memory 208, a wired NIC unit 209, and an antenna unit 210. The wired NIC unit 209 is configured to be wired connected to the transport network 3 in FIG. 1. The antenna unit 210 is configured to transmit and receive wireless signals to and from the wireless communication terminal 10 in FIG. 1. Although the wired NIC unit 209 and the antenna unit 210 are depicted as being external to the wireless communication base station 20 in FIGS. 1 and 3, in reality, the wired NIC unit 209 and the antenna unit 210 are also included as part of the configuration of the wireless communication base station 20.

[0035] The log information collection unit 201 measures log information such as the header and timestamp of the control device application traffic passing through the wired interface, and the device load such as the CPU utilization rate and temperature of the wireless communication base station 20. The log information collection unit 201 stores the measured log information in the memory 208.

[0036] The traffic estimation unit 202 estimates when the next periodic control device application traffic will pass among the control device application traffic transferred between the wireless communication unit 203 and the wired communication unit 205. The periodic control device application traffic referred to here is set from header information, etc. For example, the TSN scheduling table managed by the wired communication unit 205 determines a time slot for each priority according to a cyclic period and a priority queue, so the traffic estimation unit 202 can estimate the next passage time by calculating the return time of the control device application traffic periodically input from the core network device 30 for a certain period of time. The traffic estimation unit 202 estimates the next passage time of the control device application traffic wirelessly received from the wireless communication terminal 10 by the wireless communication unit 203 from the time slot specified by the communication device 40.

[0037] The wireless communication unit 203 has a wireless interface function for performing transmission and reception processing of wireless signals input and output from the antenna unit 210. The wireless communication unit 203 also has a modem function for performing wireless protocol processing such as control signal transmission and user data transmission with the wireless communication terminal 10. The wireless communication unit 203 also transfers control device application traffic received wirelessly to the wired communication unit 205. The wireless communication unit 203 also wirelessly transmits the control device application traffic transferred from the wired communication unit 205.

[0038] The memory control unit 204 discards from the memory 208 any log information accumulated by the log information collection unit 201 that is older than a certain period of time. The certain period of time is, for example, a period specified by a user of the communication system 1. The memory control unit 204 also discards from the memory 208 any log information that has already been reported to the communication device 40 by the log information reporting unit 207.

[0039] The wired communication unit 205 has a wired interface function for processing wired signals input and output by the wired NIC unit 209. The wired communication unit 205 also has a forwarding function for transmitting the control device application traffic transferred from the wireless communication unit 203 to the appropriate core network device 30 via a wired connection via the wired NIC unit 209 at an appropriate timing according to a cyclic period and a priority queue from a TSN scheduling table set by the core network device 30, and for receiving the control device application traffic via a wired connection from the wired NIC unit 209. The wired communication unit 205 also has a time synchronization function as part of the transport network 3 and a priority control function as part of the transport network 3.

[0040] The traffic measurement unit 206 measures the passage time of the control device application traffic transferred from the wireless communication unit 203 to the wired communication unit 205. The traffic measurement unit 206 also measures the passage time of the control device application traffic transferred from the wired communication unit 205 to the wireless communication unit 203.

[0041] The log information reporting unit 207 transmits the log information accumulated in the memory 208 to the communication device 40 at the reporting interval, when an event is detected, or in accordance with a request from the communication device 40 .

[0042] The memory 208 stores setting information such as parameters for the operation of the wireless communication base station 20, and accumulates log information.

[0043] The wired NIC unit 209 transmits the signal input from the wired communication unit 205 via a wired connection to the connected transport network 3. The wired NIC unit 209 also outputs the signal received via a wired connection from the transport network 3 to the wired communication unit 205.

[0044] The antenna unit 210 converts the signal input from the wireless communication unit 203 into radio waves and transmits the radio waves. The antenna unit 210 also outputs the received signal to the wireless communication unit 203.

[0045] 3, the wireless communication base station 20 includes two wired NIC units 209 and two antenna units 210, but it is also possible to include three or more wired NIC units 209 and three or more antenna units 210. Furthermore, in the wireless communication base station 20, the arrangement pattern of the wired NIC units 209 and the antenna units 210 is not limited to the example in FIG.

[0046] 4 is a block diagram showing an example of the configuration of core network device 30 according to this embodiment. Core network device 30 includes bridge management unit 301, log information collection unit 302, traffic estimation unit 303, memory control unit 304, wired communication unit 305, traffic measurement unit 306, log information reporting unit 307, memory 308, and wired NIC unit 309. Wired NIC unit 309 is configured to be wired connected to TSN 2 or transport network 3 in FIG. 1. Although wired NIC unit 309 is depicted in FIGS. 1 and 4 as being external to core network device 30, in reality, wired NIC unit 309 is also a part of the configuration of core network device 30.

[0047] The bridge management unit 301 manages information about the wireless communication terminals 10 that serve as TSN ports in the communication system 1 and the wired communication unit 306 of the core network device 30 in order to treat the communication system 1 as a virtual TSN switch. The information managed by the bridge management unit 301 includes combinations of TSN ports that function as TSN bridges, the residence delay times for those combinations, and the QoS required when the communication system 1 transfers application traffic. The bridge management unit 301 also has a control interface function as a virtual TSN switch seen from the CUC / CNC 60. The bridge management unit 301 also sets TSN scheduling for the wireless communication base station 20, the transport network 3, and the core network device 30 for wired section transfers when the communication system 1 transmits user data from the wireless communication terminal 10.

[0048] The log information collection unit 302 measures log information such as the header and timestamp of the control device application traffic passing through the wired interface, and the device load such as the CPU utilization rate and temperature of the core network device 30. The log information collection unit 302 stores the measured log information in the memory 308.

[0049] The traffic estimation unit 303 estimates when the next periodic control device application traffic will pass among the control device application traffic handled by the wired communication unit 305. The periodic control device application traffic referred to here is set from header information, etc. For example, since the time slots for each priority are determined according to the cyclic period and priority queue from the TSN scheduling table managed by the wired communication unit 305, the traffic estimation unit 303 can estimate the next passage time by calculating the return time of the control device application traffic periodically input from TSN2 over a certain period of time.

[0050] The memory control unit 304 sorts or organizes the log information accumulated by the log information collection unit 302 in the memory 308 .

[0051] The wired communication unit 305 has a wired interface function that processes wired signals input and output from the wired NIC unit 309. The wired communication unit 305 also has a forwarding function that transmits received control device application traffic via a wired connection from the wired NIC unit 309 connected to an appropriate TSN2 and receives control device application traffic via a wired connection from the wired NIC unit 309. The wired communication unit 305 also has a time synchronization function as part of the TSN2, a priority control function as part of the TSN2, and a time stamping and time synchronization packet correction function for establishing the communication system 1 as a bridge. The wired communication unit 305 also has a time synchronization function as part of the transport network 3 and a priority control function as part of the transport network 3.

[0052] The traffic measurement unit 306 measures the passage time of the control device application traffic that is received by the wired communication unit 305 from TSN2 and transferred to the transport network 3 destined for the wireless communication base station 20. The traffic measurement unit 306 also measures the passage time of the control device application traffic that is received by the wired communication unit 305 from the transport network 3 and transferred to TSN2.

[0053] The log information reporting unit 307 transmits the log information accumulated in the memory 308 to the communication device 40 at the reporting interval, when an event is detected, or in accordance with a request from the communication device 40 .

[0054] The memory 308 stores setting information such as parameters for operating the core network device 30, and accumulates log information.

[0055] The wired NIC unit 309 transmits the signal input from the wired communication unit 305 to the connected TSN 2 via a wired connection. The wired NIC unit 309 also outputs the signal received via a wired connection from the TSN 2 to the wired communication unit 305.

[0056] 4, the core network device 30 includes two wired NIC units 309, but it is also possible to include three or more wired NIC units 309. Furthermore, the arrangement pattern of the wired NIC units 309 in the core network device 30 is not limited to the example in FIG.

[0057] 5 is a block diagram showing an example of the configuration of a communication device 40 according to this embodiment. The communication device 40 includes a bridge management unit 401, a log information collection unit 402, a pseudo-bridge management unit 403, a memory control unit 404, a wired communication unit 405, an abnormality location estimation unit 406, an abnormality location reporting unit 407, a memory 408, and a wired NIC unit 409. The wired NIC unit 409 is configured to be wired to the wireless communication base station 20, the transport network 3, the core network device 30, etc. in FIG. 1. Although the wired NIC unit 409 is depicted in FIGS. 1 and 5 as being external to the communication device 40, in reality, the wired NIC unit 409 is also a part of the configuration of the communication device 40.

[0058] The bridge management unit 401 handles the transport network 3 as a TSN, and therefore sets a TSN scheduling table for the devices that make up the transport network 3. The bridge management unit 401 also manages the TSN scheduling table for operating the wireless communication base station 20 and the core network device 30 as TSN end stations. Information managed by the bridge management unit 401 includes the communication paths of the control device application traffic transferred between the wireless communication base station 20 and the core network device 30, the residence delay time in the devices that form each transfer path, the QoS required for the transport network 3, etc.

[0059] The log information collection unit 402 requests log information from the devices constituting the transport network 3, the wireless communication base station 20, and the core network device 30. The log information collection unit 402 also accepts notification of log information and stores the collected log information in the memory 408.

[0060] When the communication system 1 is operated as a pseudo TSN switch, the pseudo bridge management unit 403 manages the non-TSN sections of the communication path of the control device application traffic passing through the communication system 1, excluding the section from the wireless communication base station 20, which is the TSN scheduled section, to the core network device 30 via the transport network 3, as pseudo TSN sections by calculating backward from the TSN scheduling set for the TSN scheduled section based on the communication performance required of the communication system 1.

[0061] The memory control unit 404 sorts or organizes, in the memory 408, the log information accumulated by the log information collection unit 402 and the log information reported from other devices.

[0062] The wired communication unit 405 has a wired interface function for processing wired signals input / output from the wired NIC unit 409. The wired communication unit 405 also transfers a control signal for TSN scheduling from the bridge management unit 401 to an appropriate destination.

[0063] The abnormality location estimation unit 406 uses the log information stored in the memory 408 to detect whether the communication system 1 is normal or abnormal as a virtual TSN switch. When the abnormality location estimation unit 406 detects an abnormality, it estimates a device or communication path that may have caused the abnormality among the devices constituting the communication system 1. The abnormality location estimation unit 406 determines whether to request further log information from the estimated device or device related to the communication path, and if it determines to request log information, it notifies the wired communication unit 405 to transmit a log information request addressed to the device requesting the log information.

[0064] If the abnormality location estimation unit 406 detects that the communication system 1 is abnormal as a virtual TSN switch, the abnormality location reporting unit 407 reports that an abnormality has occurred and the estimated location of the abnormality to the device that is the destination of the abnormality.

[0065] The memory 408 stores setting information such as parameters for the operation of the communication device 40, and accumulates log information.

[0066] The wired NIC unit 409 transmits the signal input from the wired communication unit 405 to the connected network. The wired NIC unit 409 also outputs the signal received via wire from the connected network to the wired communication unit 405.

[0067] 6 is a block diagram showing an example of the configuration of a transport network device 70 constituting the transport network 3 according to this embodiment. The transport network device 70 includes a bridge management unit 701, a log information collection unit 702, a traffic estimation unit 703, a memory control unit 704, a wired communication unit 705, a traffic measurement unit 706, a log information reporting unit 707, a memory 708, and a wired NIC unit 709. The wired NIC unit 709 is configured to be wired connected to the wireless communication base station 20 or the core network device 30 in FIG. 1. Although the wired NIC unit 709 is depicted in FIGS. 1 and 6 as being external to the transport network device 70, in reality, the wired NIC unit 709 is also included as part of the configuration of the transport network device 70.

[0068] The bridge management unit 701 manages information for operating as a TSN switch. The information managed includes combinations of TSN ports functioning as TSN bridges, the residence delay times for those combinations, and the QoS required when the transport network device 70 transfers traffic. The bridge management unit 701 also has a control interface function as a TSN switch seen from the communication device 40.

[0069] The log information collection unit 702 measures log information such as headers and timestamps of traffic passing through the wired interface, and device loads such as CPU utilization and temperature of the transport network device 70. The log information collection unit 702 stores the measured log information in memory 708.

[0070] The traffic estimation unit 703 estimates when periodic traffic will next pass among the traffic handled by the wired communication unit 705. The periodic traffic referred to here is set from header information, etc. For example, since the time slots for each priority are determined according to the cyclic period and priority queue from the TSN scheduling table managed by the wired communication unit 705, the traffic estimation unit 703 can estimate the next passage time by calculating the return time of traffic periodically input from the wireless communication base station 20, the core network device 30, or another transport network device 70 for a certain period of time.

[0071] The memory control unit 704 sorts or organizes the log information accumulated by the log information collection unit 702 in the memory 708 .

[0072] The wired communication unit 705 has a wired interface function for processing wired signals input / output from the wired NIC unit 709. The wired communication unit 705 also has a forwarding function for transmitting received traffic via a wired connection from the wired NIC unit 709 connected to an appropriate transport network 3, and for receiving traffic via a wired connection from the wired NIC unit 709. The wired communication unit 705 also has a time synchronization function as part of the transport network 3, and a priority control function as part of the transport network 3.

[0073] The traffic measurement unit 706 measures the passage time of the traffic transferred by the wired communication unit 705 .

[0074] The log information reporting unit 707 transmits the log information accumulated in the memory 708 to the communication device 40 at the reporting interval, when an event is detected, or in accordance with a request from the communication device 40 .

[0075] The memory 708 stores setting information such as parameters for operating the core network device 30, and accumulates log information.

[0076] The wired NIC unit 709 transmits the signal input from the wired communication unit 705 via a wired connection to the connected transport network 3. The wired NIC unit 709 also outputs the signal received via a wired connection from the transport network 3 to the wired communication unit 705.

[0077] 6, the transport network device 70 includes two wired NIC units 709, but may include three or more wired NIC units 709. In addition, the arrangement pattern of the wired NIC units 709 in the transport network device 70 is not limited to the example in FIG.

[0078] FIG. 7 is a diagram illustrating one-way communication traffic when the communication system 1 according to the present embodiment operates as a virtual TSN switch. The upper part of FIG. 7 shows that in the communication system 1, there is input from the time-sensitive network from TSN2 at (1), and output to the time-sensitive network to TSN2 at (2). Looking at the breakdown of the communication system 1, as shown in the lower part of FIG. 7, it can be seen as a non-TSN section, which is a wireless section between the wireless communication terminal 10 and the wireless communication base station 20, and a TSN section, which is a wired section between the wireless communication base station 20, the transport network 3, and the core network device 30. In this case, since TSN scheduling is performed in the TSN section, the input traffic in (3) can be calculated by back-calculating from the scheduling in the TSN section and the operation as a virtual TSN switch required of the communication system 1. In other words, the communication system 1 can treat the non-TSN section as a pseudo-TSN.

[0079] FIG. 8 is a diagram illustrating time-sensitive time-division scheduling for one-way communication traffic when the communication system 1 according to this embodiment operates as a virtual TSN switch. In FIG. 8, the horizontal axis represents the time axis. Note that (1), (2), and (3) in FIG. 8 correspond to (1), (2), and (3) in FIG. 7. (1) and (2) are determined by the requested QoS parameters, TSN scheduling, and input / output TSN ports input to the communication system 1 from the CUC / CNC 60, which controls the scheduling of the entire communication network 80 including TSN 2. In the example of FIG. 8, the communication system 1 is required to have an overall delay budget 803 of 3 ms.

[0080] The communication system 1 can calculate the time division scheduling to be realized in (3) by having the wireless communication base station 20, the transport network 3, and the core network device 30 perform TSN scheduling for the communication performance settings of the user data transmission path in the non-TSN section, which is the wireless section, based on the requested QoS parameters, TSN scheduling, and input / output TSN ports. Specifically, as shown in Fig. 8, if the delay budget 802 in the TSN section is 1 ms, the delay budget 801 in the pseudo-TSN section, which is the non-TSN section, can be calculated as 2 ms from the difference between the delay budget 803 of 3 ms and the delay budget 802 of 1 ms.

[0081] For example, in the communication system 1, if the received traffic deviates from the time-division scheduling that should be realized in (3), this means that the QoS could not be realized in the preceding non-TSN section. In the example of Figure 8, this is the case when a delay of 2 ms or more occurs. Therefore, if the communication system 1 cannot realize the requested QoS, TSN scheduling, etc. as a virtual TSN switch, it is possible to check the details by checking the log information in the non-TSN section. The same is true for traffic in the reverse direction, but in the TSN section, each device that makes up the TSN section operates with its own time-division scheduling, so the communication system 1 can narrow down the devices that could not realize the QoS in more detail.

[0082] FIG. 9 is a sequence diagram showing an example of operations up to the start of traffic measurement triggered by power-on of the wireless communication terminal 10 in the communication system 1 according to this embodiment.

[0083] In step ST101, when the wireless communication terminal 10 is powered on, it performs a registration operation with the communication system 1, which is a typical cellular communication system, and a session establishment operation according to the service requested by the wireless communication terminal 10. The operation of step ST101 also includes operations such as authentication, security, and billing. When the operation of step ST101 is completed, in the communication system 1, a wireless section route is set by the wireless communication terminal 10 and the wireless communication base station 20, and a wired section route is set by the wireless communication base station 20, the transport network 3, and the core network device 30, making it possible to connect to an external network from the perspective of the wireless communication terminal 10. The wireless communication terminal 10 can transparently forward wired traffic from TSN2, which is an external network to which the wireless communication terminal 10 is connected by wire, to TSN2, which is an external network connected to the core network device 30.

[0084] In step ST102, the CUC / CNC 60, which is a device that manages the external network, notifies the communication system 1 of a QoS request based on QoS parameters, TSN scheduling to a TSN port, etc., in order to operate the communication system 1 as a virtual TSN switch in the external network. As a result, in the communication system 1, the core network device 30 is set as an interface.

[0085] In step ST103, the bridge management unit 301 of the core network device 30 converts the QoS parameters, TSN scheduling, and the like required for operating the communication system 1 as a virtual TSN switch in the external network into parameters required for the wireless section route and parameters required for the wired section route within the communication system 1. The bridge management unit 301 of the core network device 30 notifies the transport network 3, the wireless communication base station 20, and the wireless communication terminal 10 that constitute the communication system 1 of the converted parameters. This allows the communication system 1 to modify the session that the wireless communication terminal 10 established in step ST101.

[0086] In step ST104, the bridge management unit 301 of the core network device 30 notifies the wireless communication base station 20 and the transport network 3 of the QoS request and the TSN scheduling to the TSN port in order to set the optimal transfer scheduling of the wired section route by the wireless communication base station 20, the transport network 3, and the core network device 30 in each device as TSN scheduling.

[0087] In step ST105, the bridge management unit 301 of the core network device 30 notifies the communication device 40 of the scheduling results obtained in steps ST103 and ST104.

[0088] In step ST106, the pseudo bridge management unit 403 of the communication device 40 calculates pseudo TSN scheduling for treating the non-TSN section as a pseudo TSN section by working backwards, that is, TSN scheduling for the pseudo TSN section.

[0089] In step ST107, the log information collection unit 402 of the communication device 40 instructs the wireless communication terminal 10, the wireless communication base station 20, the transport network 3, and the core network device 30 to measure traffic. At this time, the log information collection unit 402 of the communication device 40 instructs the devices related to the non-TSN section, i.e., the wireless communication terminal 10 and the wireless communication base station 20, to perform measurement based on the calculation result of the TSN scheduling of the pseudo-TSN section.

[0090] FIG. 10 is a sequence diagram showing an example of traffic monitoring triggered by the communication device 40 in the communication system 1 according to the present embodiment.

[0091] In step ST201, when the communication device 40 detects that time has elapsed to the point where the measurement period has expired, or when a request for log collection is made by a user, a user of the communication system 1, etc., the sequence is started.

[0092] In step ST202, the log information collection unit 402 of the communication device 40 instructs each related device in the communication system 1, namely the wireless communication terminal 10, the wireless communication base station 20, the transport network 3, and the core network device 30, to report a log.

[0093] In step ST203, the radio communication terminal 10, the radio communication base station 20, the transport network 3, and the core network device 30 that have received the log report instruction report the log information to the communication device 40.

[0094] FIG. 11 is a sequence diagram showing an example of traffic monitoring triggered by an event other than that from the communication device 40 in the communication system 1 according to the present embodiment.

[0095] In step ST301, if any of the radio communication terminal 10, the radio communication base station 20, the transport network 3, and the core network device 30 does not receive the expected traffic, this is taken as an opportunity to start the sequence.

[0096] In step ST302, the wireless communication terminal 10, or the wireless communication base station 20, or the transport network 3, or the core network device 30 that did not receive the expected traffic notifies the communication device 40 of log information indicating that the expected traffic was not received.

[0097] In step ST303, log information collection section 402 of communication device 40 instructs, based on the log information notified in step ST302, wireless communication terminal 10, wireless communication base station 20, transport network 3, or core network device 30 that notified the log information, to report a log. Note that log information collection section 402 of communication device 40 may also instruct devices other than the device that notified the log information in step ST302 to report a log.

[0098] In step ST304, the radio communication terminal 10, the radio communication base station 20, the transport network 3, or the core network device 30 that has received the instruction in step ST303 reports the log information to the communication device 40.

[0099] In step ST305, the abnormality location estimation unit 406 of the communication device 40 estimates the location of the failure based on the log information collected from the wireless communication terminal 10, the wireless communication base station 20, the transport network 3, or the core network device 30.

[0100] In the communication device 40, each component operates as follows in the operations of the sequence diagrams shown in Figures 9 to 11. Based on the first quality of service required for the communication system 1, the bridge management unit 401 performs settings according to the second quality of service required for the wired connection section for network nodes in the wired connection section among the network nodes that form the communication path of traffic in the communication system 1. In the example of Figure 1, the network nodes in the wired connection section correspond to the wireless communication base station 20, the transport network 3, and the core network device 30. In addition, in the example of Figure 8, the first quality of service corresponds to 3 ms of the delay budget 803, and the second quality of service corresponds to 1 ms of the delay budget 802.

[0101] Next, the pseudo bridge management unit 403 performs setting for the network nodes in the wireless connection section among the network nodes according to a third quality of service required in the wireless connection section, based on the difference between the first quality of service and the second quality of service. In the example of Fig. 1, the network nodes in the wireless connection section correspond to the wireless communication terminal 10 and the wireless communication base station 20. In the example of Fig. 8, the third quality of service corresponds to 2 ms of the delay budget 801.

[0102] Next, the log information collection unit 402 acquires, from the network node, log information indicating the communication state when the network node transmits and receives traffic. For example, the log information collection unit 402 can acquire the log information from the network node at a specified interval, when a specified event is detected in the network node, or in response to a request from the log information collection unit 402 to the network node.

[0103] Then, the anomaly location estimation unit 406 estimates a network node or a route between network nodes that does not satisfy the second quality of service or the third quality of service based on the log information. For example, the anomaly location estimation unit 406 can estimate a network node or a route between network nodes that does not satisfy the second quality of service or the third quality of service by using a timestamp included in the log information acquired from the network node when the second quality of service or the third quality of service is not satisfied.

[0104] In the present embodiment, the time-sensitive network including the communication system 1 is assumed to be TSN, but is not limited to this. The time-sensitive network including the communication system 1 may be DetNet (Deterministic Networking).

[0105] Next, the hardware configuration of the communication device 40 will be described. In the communication device 40, the wired NIC unit 409 is a network interface card. The bridge management unit 401, the log information collection unit 402, the pseudo bridge management unit 403, the memory control unit 404, the wired communication unit 405, the abnormality location estimation unit 406, the abnormality location reporting unit 407, and the memory 408 are realized by processing circuits. The processing circuit may be a processor and memory that executes a program stored in memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0106] FIG. 12 is a diagram showing an example of the configuration of a processing circuit 90 that implements the communication device 40 according to this embodiment, where the processing circuit is configured with a processor 91 and a memory 92. The processing circuit 90 shown in FIG. 12 is a control circuit and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. The processing circuit 90 implements each function by having the processor 91 read and execute the program stored in the memory 92. That is, the processing circuit 90 includes the memory 92 for storing a program that results in the processing of the communication device 40 being executed. This program can also be said to be a program that causes the communication device 40 to execute each function implemented by the processing circuit 90. This program may be provided by a storage medium on which the program is stored, or by other means such as a communication medium.

[0107] The above program can also be said to be a program that causes the communication device 40 to execute the following steps: a first step in which the bridge management unit 401 configures network nodes in the wired connection section among the network nodes that serve as communication paths for traffic in the communication system 1, based on the first service quality required for the communication system 1, in accordance with the second service quality required in the wired connection section; a second step in which the pseudo-bridge management unit 403 configures network nodes in the wireless connection section among the network nodes in accordance with the third service quality required in the wireless connection section, based on the difference between the first service quality and the second service quality; a third step in which the log information collection unit 402 acquires log information from the network nodes that indicates the communication status when the network nodes send and receive traffic; and a fourth step in which the abnormality location estimation unit 406 estimates, based on the log information, network nodes or routes between network nodes that do not satisfy the second service quality or the third service quality or

[0108] Here, the processor 91 is, for example, a CPU, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc. The memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disc).

[0109] FIG. 13 is a diagram illustrating an example of a processing circuit 93 that implements the communication device 40 according to this embodiment and is configured with dedicated hardware. The processing circuit 93 illustrated in FIG. 13 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The processing circuit may be partially implemented with dedicated hardware and partially implemented with software or firmware. In this way, the processing circuit can implement each of the above-described functions using dedicated hardware, software, firmware, or a combination thereof.

[0110] The hardware configuration of the communication device 40 has been described, but the wireless communication terminal 10, the wireless communication base station 20, the core network device 30, and the transport network device 70 that is the transport network 3 also have the same hardware configuration.

[0111] As described above, according to the present embodiment, the communication device 40 controls the operation of the communication system 1, which operates as a virtually time-sensitive switch. The communication device 40 calculates the required performance of internal transport traffic in the communication system 1 from the required performance of application traffic transferred within the communication system 1, and configures the communication links between network nodes constituting the communication path of the application traffic to perform one or more time-sensitive communications. Furthermore, for sections that do not support time-sensitive communications, the communication device 40 treats them as one or more pseudo-time-sensitive communication links by back-calculating the required performance of the application traffic and the required performance of one or more time-sensitive communication links, and simultaneously notifies the communication device of the ideal return time and instructs the communication device 40 to monitor the traffic transit time. Each network node evaluates the difference between the actual return time of the traffic and the ideal return time, and for traffic whose evaluation results do not satisfy the required performance, reports log information to the communication device 40, storing the traffic information together with a timestamp.

[0112] The communication device 40 monitors traffic by polling network nodes or operating as a trap server from the network nodes and collecting log information including relevant traffic information and timestamps. When application traffic transferred within the communication system 1 does not meet required performance, the communication device 40 collects traffic information and timestamps for the application traffic that do not meet the required performance in one or more time-sensitive communication links or one or more pseudo time-sensitive communication links that form the internal transfer path. The communication device 40 estimates the network node or communication link that did not meet the required performance by using the collected traffic information and timestamps.

[0113] As a result, the communication device 40 used in the communication system 1, which operates as a virtual time-sensitive switch, can detect when E2E, for example, communication that does not meet the QoS required by the communication system 1, occurs instantaneously, and can estimate the bottleneck, i.e., the network node or route that is causing the bottleneck, in order to meet the QoS.

[0114] It should be noted that the transport network 3 can achieve the same effect by performing equivalent settings on a layer 3 switch. Furthermore, the TSN 2 does not necessarily have to be a TSN-compliant network, and it is possible to achieve the same effect by performing equivalent settings on any time-sensitive network that performs wired transfer scheduling control in synchronization with time with high precision.

[0115] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0116] 1 Communication system, 2 TSN, 3 Transport network, 10 Wireless communication terminal, 20 Wireless communication base station, 30 Core network device, 40 Communication device, 50 Control equipment, 60 CUC / CNC, 70 Transport network device, 80 Communication network, 90, 93 Processing circuit, 91 Processor, 92, 108, 208, 308, 408, 708 Memory, 101, 201, 302, 402, 702 Log information collection unit, 102, 202, 303, 703 Traffic estimation unit, 103, 203 Wireless communication unit, 104, 204, 304, 404, 704 Memory control unit, 105, 205, 305, 405, 705 Wired communication unit, 106, 206, 306, 706 Traffic measurement unit, 107, 207, 307, 707 log information reporting unit, 109, 209, 309, 409, 709 wired NIC unit, 110, 210 antenna unit, 301, 401, 701 bridge management unit, 403 pseudo bridge management unit, 406 abnormality location estimation unit, 407 abnormality location reporting unit.

Claims

1. A communication device for use in a communication system that operates as a virtual time-sensitive switch, comprising: a bridge management unit that performs setting, based on a first quality of service required for the communication system, on network nodes in a wired connection section among network nodes that serve as a communication path of traffic in the communication system, in accordance with a second quality of service required in the wired connection section; a pseudo bridge management unit that performs setting for a network node in a wireless connection section among the network nodes according to a third quality of service required in the wireless connection section based on a difference between the first quality of service and the second quality of service; a log information collection unit that acquires, from the network node, log information indicating a communication state when the network node transmits and receives the traffic; an anomaly location estimation unit that estimates the network node or a route between the network nodes that does not satisfy the second quality of service or the third quality of service based on the log information; A communication device comprising:

2. the log information collection unit acquires the log information from the network node at a specified interval, when a specified event is detected in the network node, or in response to a request from the log information collection unit to the network node; 2. The communication device according to claim 1 .

3. the anomaly location estimation unit estimates the network node or a route between the network nodes that does not satisfy the second service quality or the third service quality by using a timestamp included in the log information acquired from the network node when the second service quality or the third service quality is not satisfied.

3. The communication device according to claim 2.

4. The time-sensitive network including the communication system is Time Sensitive Networking.

2. The communication device according to claim 1 .

5. The time-sensitive network including the communication system is Deterministic Networking.

2. The communication device according to claim 1 .

6. A communication device according to any one of claims 1 to 5; a network node which is a communication path of the traffic and which reports log information indicating a communication state when transmitting and receiving the traffic to the communication device; A communication system comprising:

7. 1. A control circuit for controlling a communication device used in a communication system that operates as a virtually time-sensitive switch, comprising: based on a first quality of service required for the communication system, setting a network node in a wired connection section among network nodes that form a communication path of traffic in the communication system in accordance with a second quality of service required in the wired connection section; setting a third quality of service required for a network node in a wireless connection section among the network nodes, based on a difference between the first quality of service and the second quality of service; acquiring, from the network node, log information indicating a communication state when the network node transmits and receives the traffic; estimating the network node or a route between the network nodes that does not satisfy the second quality of service or the third quality of service based on the log information; A control circuit for causing the communication device to execute the above.

8. A storage medium storing a program for controlling a communication device used in a communication system that operates as a virtual time-sensitive switch, The program is based on a first quality of service required for the communication system, setting a network node in a wired connection section among network nodes that form a communication path of traffic in the communication system in accordance with a second quality of service required in the wired connection section; setting a third quality of service required for a network node in a wireless connection section among the network nodes, based on a difference between the first quality of service and the second quality of service; acquiring, from the network node, log information indicating a communication state when the network node transmits and receives the traffic; estimating the network node or a route between the network nodes that does not satisfy the second quality of service or the third quality of service based on the log information; A storage medium for causing the communication device to execute the above.

9. A communication method for a communication device used in a communication system that operates as a virtual time-sensitive switch, comprising: a first step in which a bridge management unit performs setting, based on a first quality of service required for the communication system, for network nodes in a wired connection section among network nodes that serve as a communication path for traffic in the communication system, in accordance with a second quality of service required for the wired connection section; a second step in which a pseudo bridge management unit performs setting on a network node in a wireless connection section among the network nodes according to a third quality of service required in the wireless connection section based on a difference between the first quality of service and the second quality of service; a third step of acquiring, from the network node, log information indicating a communication state when the network node transmits and receives the traffic by a log information collector; a fourth step of an anomaly location estimation unit estimating, based on the log information, the network node or a route between the network nodes that does not satisfy the second quality of service or the third quality of service; A communication method comprising: