An object of the present disclosure is to provide a remote unit (RU) apparatus that can effectively utilize statistical information of packets generated in a RU apparatus and a distributed unit (DU) apparatus that execute separated functions in a base station. A RU apparatus (10) according to the present disclosure includes: a reception unit (11) that receives a packet from a DU apparatus (20) that executes processing of a higher-level layer than a layer to be executed by the RU apparatus (10) among communication functions of a base station that are divided into a plurality of layers; and a transmission unit (12) that transmits an alarm signal to the DU apparatus (20) or a management apparatus that manages a network when statistical information regarding the received packet satisfies a predetermined criterion.

TECHNICAL FIELD

The present disclosure relates to an RU apparatus, a DU apparatus, a communication system, a communication method, and a program.

BACKGROUND ART

In recent years, a radio access network in which a baseband unit and a radio unit of a base station are separated and the baseband unit and the radio unit are connected via a fronthaul has been used. Open-Radio Access Network (O-RAN) fronthaul specifications defined in an O-RAN alliance define fronthaul specifications between an O-RAN Radio Unit (O-RU) being equivalent to the radio unit and an O-RAN Distributed Unit (O-DU) being equivalent to the baseband unit. The O-RAN fronthaul specifications have one object to facilitate connection between an O-DU of a certain vendor and an O-RU of a different vendor and to achieve multivendor environment of a radio access network.

Non Patent Literature 1 defines specifications regarding a Management (M)-Plane defined for transmitting administrative data between an O-RU and an O-DU. Non Patent Literature 1 discloses that the O-RU generates statistical information by totalizing packets received from the O-DU.

CITATION LIST

Non Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, Non Patent Literature 1 does not disclose a specific utilization method of the statistical information generated by the O-DU or the O-RU. This is also true in a Centralized Radio Access Network (C-RAN) adopted in Long Term Evolution (LTE) defined in 3rd Generation Partnership Project (3GPP).

An object of the present disclosure is to provide an RU apparatus, a DU apparatus, a communication system, a communication method, and a program, that include a means for utilizing statistical information of packets generated in the RU apparatus and the DU apparatus that execute separated functions of a base station.

Solution to Problem

A remote unit (RU) apparatus according to a first aspect of the present disclosure includes: a reception unit configured to receive a packet from a distributed unit (DU) apparatus configured to execute processing of a higher-level layer than a layer to be executed by a remote unit (RU) apparatus among communication functions of a base station that are divided into a plurality of layers; and a transmission unit configured to transmit an alarm signal to the DU apparatus or a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

A DU apparatus according to a second aspect of the present disclosure includes: a reception unit configured to receive a packet from an RU apparatus configured to execute processing of a lower-level layer than a layer to be executed by the DU apparatus among communication functions of a base station that are divided into a plurality of layers; and a transmission unit configured to transmit an alarm signal to a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

A communication system according to a third aspect of the present disclosure includes: an RU apparatus configured to execute a part of layer processing among communication functions of a base station that are divided into a plurality of layers; a DU apparatus configured to transmit and receive a packet to and from the RU apparatus, and execute processing of a higher-level layer than a layer to be executed by the RU apparatus; and a management apparatus configured to manage a network including the RU apparatus and the DU apparatus, wherein at least one of the RU apparatus and the DU apparatus transmits an alarm signal to the management apparatus when statistical information regarding the received packet satisfies a predetermined criterion, and the management apparatus transmits the predetermined criterion to at least one of the RU apparatus that transmits the alarm signal and the DU apparatus that transmits the alarm signal.

A communication method according to a fourth aspect of the present disclosure includes: receiving a packet from a distributed unit (DU) apparatus configured to execute processing of a higher-level layer than a layer to be executed by a remote unit (RU) apparatus among communication functions of a base station that are divided into a plurality of layers; and transmitting, when statistical information regarding the received packet satisfies a predetermined criterion, an alarm signal to the DU apparatus or a management apparatus configured to manage a network.

A program according to a fifth aspect of the present disclosure causes a computer to execute: receiving a packet from a distributed unit (DU) apparatus configured to execute processing of a higher-level layer than a layer to be executed by a remote unit (RU) apparatus among communication functions of a base station that are divided into a plurality of layers; and transmitting an alarm signal to the DU apparatus or a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide an RU apparatus, a DU apparatus, a communication system, a communication method, and a program that are able to effectively utilize statistical information of packets generated in an RU apparatus and a DU apparatus that execute functions of separated base stations.

EXAMPLE EMBODIMENT

First Example Embodiment

Hereinafter, example embodiments of the present disclosure will be explained with reference to the drawings. A configuration example of an RU apparatus10according to a first example embodiment will be explained with reference toFIG.1. The RU apparatus may be a computer apparatus that operates by a processor executing a program stored in a memory.

The RU apparatus10may execute processing of a lower-level layer among communication functions of a base station divided into a plurality of layers. Meanwhile, a DU apparatus20may execute processing of a higher-level layer than the layer to be executed by the RU apparatus10. The RU apparatus10performs wireless communication with a communication terminal existing in a communication area formed by the RU apparatus10. The communication terminal may be, for example, a smart phone terminal, an Internet of Things (IoT) terminal, or the like. Alternatively, the communication terminal may be an apparatus defined as User Equipment (UE) in 3GPP. The base station may be, for example, an evolved Node B (eNB) that is defaulted as a base station that supports Long Term Evolution (LTE) in 3GPP, or may be a base station that supports so-called 5G.

The RU apparatus10includes a reception unit11and a transmission unit12. The reception unit11and the transmission unit12may be software or modules that execute processing by the processor executing a program stored in a memory. Alternatively, the reception unit11and the transmission unit12may be hardware such as a circuit or a chip.

The reception unit11receives a packet from the DU apparatus20. The RU apparatus10and the DU apparatus20may be connected, for example, via a fixed communication network or may be connected via a wireless communication network. The packet to be received by the RU apparatus10may be, for example, control data required for the communication terminal to utilize a mobile network provided by a communication carrier. Furthermore, the packet to be received by the RU apparatus10may be user data addressed to the communication terminal. Further, the packet to be received by the RU apparatus10may be management data used for managing a communication network including the RU apparatus10and the DU apparatus20.

The transmission unit12transmits an alarm signal to the DU apparatus20or a management apparatus that manages a network when statistical information regarding the received packet satisfies a predetermined criterion.

The statistical information regarding the received packet may be, for example, information acquired by classifying the received packet by using the number of received packets. The number of received packets may be, for example, the number of normally received packets, the number of packets including errors received, the number of packets received at a predetermined timing, the number of packets that cannot be received at a predetermined timing, or the like. The predetermined criterion may be, for example, that a ratio of at least one of the number of normally received packets, the number of packets including an error being received, the number of packets received at a predetermined timing, and the number of packets that cannot be received at a predetermined timing to a total number of received packets exceeds or falls below a predetermined threshold value.

The predetermined criterion may be, for example, a type of the received packet.

The RU apparatus10may receive at least one of information indicating a predetermined criterion and information indicating a predetermined threshold value from the DU apparatus20or the management apparatus that manages a network.

The management apparatus that manages a network may be, for example, an apparatus that manages a network including the DU apparatus20and the RU apparatus10. Alternatively, the management apparatus may be an apparatus that manages a network including an access network including the DU apparatus20and the RU apparatus10, and a core network that manages the access network.

The alarm signal may be a signal used for notifying an abnormal state, a failure, a fault, or the like occurring in the RU apparatus10. Alternatively, the alarm signal may be a signal used for notifying an abnormal state, a failure, a fault, or the like occurring on a transmission path between the RU apparatus10and the DU apparatus20.

Alternatively, the alarm signal may be a signal used for notifying that a logical connection of at least one of a C-Plane and a U-Plane between the RU apparatus10and the DU apparatus20is unstable.

The transmission unit12may transmit an alarm signal to the management apparatus via the DU apparatus20, or may transmit an alarm signal to the management apparatus not via the DU apparatus20. Further, the transmission unit12may transmit an alarm signal to the DU apparatus20via the management apparatus, or may transmit an alarm signal to the DU apparatus20not via the management apparatus.

In addition, the transmission unit12may stop the transmission of the alarm signal to the DU apparatus20or the management apparatus that manages the network when the statistical information regarding the received packet does not satisfy a predetermined criterion.

Next, a configuration example of the DU apparatus20according to the first example embodiment will be explained with reference toFIG.2. The DU apparatus20may be a computer apparatus that operates by a processor executing a program stored in a memory.

The DU apparatus20includes a reception unit21and a transmission unit22. The reception unit21and the transmission unit22may be software or modules that execute processing by the processor executing a program stored in a memory. Alternatively, the reception unit21and the transmission unit22may be hardware such as a circuit or a chip.

The reception unit21receives a packet from the RU apparatus10. The packet received by the DU apparatus20may be, for example, control data required for the communication terminal to use a mobile network provided by a communication carrier. Furthermore, the packet received by the DU apparatus20may be user data transmitted from the communication terminal via the RU apparatus10. Further, the packet received by the DU apparatus20may be management data used for managing a communication network including the RU apparatus10and the DU apparatus20.

The transmission unit22transmits an alarm signal to the management apparatus that manages the network when the statistical information regarding the received packet satisfies a predetermined criterion. The statistical information regarding the received packet is the same as the statistical information in the RU apparatus10.

The predetermined criterion may also be the same as the predetermined criterion in the RU apparatus10.

The DU apparatus20may receive at least one of information indicating a predetermined criterion and information indicating a predetermined threshold value from a management apparatus that manages a network.

As described above, the RU apparatus10can transmit the alarm signal generated based on the received packet to another apparatus other than the RU apparatus10. As a result, an administrator who manages the DU apparatus20or an administrator who manages the management apparatus can detect a fault or the like occurring in the RU apparatus10or a transmission path between the RU apparatus10and the DU apparatus20by receiving the alarm signal. In other words, the administrator who manages the DU apparatus20does not need to actively acquire the statistical information being managed by the RU apparatus10, and does not need to analyze the statistical information in order to detect a fault or the like occurring in the RU apparatus10or the like. Therefore, by using the RU apparatus10, a management load of an administrator who manages a network including the RU apparatus10and the DU apparatus20can be reduced.

Furthermore, the DU apparatus20can also transmit an alarm signal to other apparatuses other than the DU apparatus20, similarly to the RU apparatus10. As a result, the administrator who manages the management apparatus can detect a fault or the like occurring in the DU apparatus20or the transmission path between the RU apparatus10and the DU apparatus20by receiving the alarm signal. The administrator who manages the management apparatus does not need to actively acquire the statistical information managed by the DU apparatus20, and does not need to analyze the statistical information in order to detect a fault or the like occurring in the DU apparatus20or the like. Therefore, by using the DU apparatus20, the management load of the administrator who manages the network including the RU apparatus10and the DU apparatus20can be reduced.

Second Example Embodiment

Next, a configuration example of a communication system according to a second example embodiment will be explained with reference toFIG.3. The communication system inFIG.3includes an O-RU entity30and an O-DU entity40defined in an O-RAN alliance. Further, a Network Management System (NMS)50is a system that manages the O-RU entity30and the O-DU entity40.

The NMS50is equivalent to the management apparatus. The NMS50may be replaced with a Service Management and Orchestration System (SMO). The O-RU entity30is equivalent to the RU apparatus10. The O-DU entity40is equivalent to the DU apparatus20. In the following explanation, it is assumed that the O-RU entity30includes the reception unit11and the transmission unit12of the RU apparatus10, and the O-DU entity40includes the reception unit21and the transmission unit22of the DU apparatus20.

The O-RU entity30executes, for example, Radio Frequency (RF) processing and processing related to a Low-PHY layer. The Low-PHY layer may be, for example, a layer on which processing related to Fast Fourier Transform (FFT), inverse FFT (iFFT), digital beamforming, and Physical Random Access Channel (PRACH) extraction is executed. The PRACH extraction is, for example, processing in which, when the UE establishes a connection with the O-RU entity30, the O-RU entity30extracts or detects the PRACH, which is a signal transmitted first from the UE. The O-RU entity30may be a Transmission Reception Point (TRP) or a Radio Remote Head (RRH) defined in 3GPP.

The O-DU entity40executes, for example, processing related to a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a High-PHY layer. The High-PHY layer is, for example, a layer on which processing related to Forward Error Correction (FEC) encoding, FEC decoding, scrambling, modulating, and demodulating is executed. The processing executed in the O-RU entity30and the O-DU entity40is not limited to the above-described contents, and may be changed from the above-described contents.

The O-RU entity30communicates with the O-DU entity40via a transmission path61and a transmission path62. The transmission path61transmits C-Plane data and U-Plane data. The transmission path62transmits M-Plane data. The C-Plane data, the U-Plane data, and the M-Plane data may be transmitted as packets. The transmission path61and the transmission path62may be referred to as Fronthaul (FH) or a fronthaul interface. The transmission path61and the transmission path62may require a predetermined frequency band.

The NMS50is connected to the O-DU entity40via a network. For example, the NMS50may set management data in the O-DU entity40and further set management data in the O-RU entity30via the O-DU entity40. The management data may be transmitted as M-Plane data to the O-RU entity30via the transmission path62. The management data may be set by using YANG DATA MODEL defined in the O-RAN Alliance. In addition, the management data may be set in the O-RU entity30by using, for example, an o-ran-supervision.yang Module or an o-ran-performance-management.yang Module.

The management data may be preset in at least one of the O-DU entity40and the O-RU entity30.

The C-Plane is a protocol for transferring a control signal. The U-Plane is a protocol for transferring user data. In the C-Plane and U-Plane, a protocol stack that transmits a signal used in an enhanced Common Public Radio Interface (eCPRI) or Radio over Ethernet (RoE) by using Ethernet/IP/User Datagram Protocol (UDP) is supported. Alternatively, the C-Plane and the U-Plane may support a protocol stack that transmits a signal used in eCPRI or RoE by directly using Ethernet. The M-Plane is a protocol for transferring a monitoring signal used for monitoring or maintaining an apparatus.

Next, statistical information generated by the O-RU entity30or the O-DU entity40will be explained. The O-RU entity30or the O-DU entity40measures a packet received as C-Plane data or U-Plane data by using various counters.

The various counters may be, for example, RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL. The RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL are definitions of counters defined as measurement-object in Rx Window Statistics in the O-RAN alliance.

Herein, before explaining the RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL in detail, a method of delay management executed in the O-RU entity30will be explained with reference toFIG.4.FIG.4illustrates transmitting a packet from the O-DU entity40to the O-RU entity30. A method of delay management executed in the O-DU entity40is the same as that of the O-RU entity30, and thus a detailed explanation thereof will be omitted.

FIG.4illustrates that the O-RU entity30and the O-DU entity40perform delay management by using the same time axis. In short, the O-RU entity30and the O-DU entity40perform time synchronization. T1to T4indicate times.

The time T4is a timing at which the O-RU entity30transmits wireless data to the UE. Delay management is performed in the O-RU entity30and the O-DU entity40in order for the O-RU entity30to transmit wireless data at a predetermined time T4. The O-RU entity30needs to complete various kinds of processing such as iFFT, analog conversion, and beamforming in such a way as to be in time for transmission of wireless data at the time T4. A time from a time T3′ to the time T4is a time for the O-RU entity30to execute various kinds of processing such as iFFT, analog conversion, and beamforming. InFIG.4, the time from the time T3′ to the time T4is taken as an O-RU processing delay.

In the O-RU entity30, a reception window is set before the time T4, which is a timing at which wireless data are transmitted, for a time of the O-RU processing delay. A period during which the O-RU entity30can normally receive a packet is defined as a reception window. In short, when receiving a packet in the reception window, the O-RU entity30can transmit the received packet as wireless data at time T4, which is a timing at which wireless data are transmitted. The reception window indicates a period before the time T3′. The reception window may be a period from the time T2, which is a timing at which the O-DU entity40transmits a packet, to the time T3′, or may be a period from an arbitrary timing from the time T2to the time T3′, to the time T3′.

A period from the time T2to the time T3is a transmission delay between the O-DU entity40and the O-RU entity30, and may be referred to as a fronthaul delay. The fronthaul is a line between the O-DU entity40and the O-RU entity30. For example, an optical fiber or the like may be used as the fronthaul. Standards for the fronthaul are defined in the O-RAN Alliance.

The period from the time T1to the time T2indicates an O-DU processing delay. The O-DU processing delay is a period in which processing for the O-DU entity40to transmit a packet is executed. A predetermined period from the time T2may be defined as a transmission window in the O-DU entity40. The transmission window is a period in which a packet transmitted from the O-DU entity40can reach the O-RU entity30by the reception window in the O-RU entity30.

InFIG.4, an example in which a reception window is set in the O-RU entity30has been explained, but a reception window is also set in the O-DU entity40. The O-DU entity40can normally transmit data to other apparatuses by receiving a packet transmitted from the O-RU entity30in the reception window.

Next, details of RX_ON_TIME, RX_ON_TIME C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL will be explained. RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL may be indices by which the O-RU entity30or the O-DU entity40counts the number of packets. The O-RU entity30or the O-DU entity40may count RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL for packets arriving during a predetermined monitoring period. The monitoring period may be a period measured by C/U-plane monitoring period or C/U-plane Monitoring Timer. Furthermore, the monitoring period may be a configured-cu-monitoring-interval.

RX_ON_TIME counts the number of packets of U-Plane data that have arrived at the O-RU entity30or the O-DU entity40within the reception window. The number of packets of the U-Plane data that have arrived in the reception window includes a packet having a sequence number error or a packet having an error such as a corrupted (corruption) packet.

RX_ON_TIME_C counts the number of packets of C-Plane data that have arrived at the O-RU entity30or the O-DU entity40within the reception window. The number of packets of the C-Plane data that have arrived in the reception window includes a packet having a sequence number error or a packet having an error such as a corrupted (corruption) packet.

RX_EARLY counts the number of packets of U-Plane data that have arrived at the O-RU entity30or the O-DU entity40before the reception window starts. RX_EARLY_C counts the number of packets of C-Plane data that have arrived at the O-RU entity30or the O-DU entity40before the reception window starts.

RX_LATE counts the number of packets of U-Plane data that have arrived at the O-RU entity30or the O-DU entity40after the reception window ends. RX_LATE_C counts the number of packets of C-Plane data that have arrived at the O-RU entity30or the O-DU entity40after the reception window ends.

RX_TOTAL counts the number of all packets received during a given monitoring period, including the reception window. All packets include C-Plane data and U-Plane data. Further, all the packets include all packets counted in RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, and RX_LATE_C. Also, all the packets may include packets counted in other counters that differ from RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, and RX_LATE_C.

Next, setting processing of management data in the O-DU entity40according to the second example embodiment will be explained with reference toFIG.5. First, the reception unit21of the O-DU entity40receives management data from the NMS50(S10). The management data include, for example, at least one of a packet type to be measured, an abnormality detection method, and a threshold value for notifying an alarm. The packet type to be measured is information indicating, for example, whether to measure a packet that is C-Plane data, whether to measure a packet that is U-Plane data, or whether to measure packets of both C-Plane data and U-Plane data. When the packets of both the C-Plane data and the U-Plane data are measured, the C-Plane data and the U-Plane data may be measured distinctively, or the C-Plane data and the U-Plane data may be measured without distinction. The management data may be trigger information for the O-RU entity30or the O-DU entity40to send an alarm.

The abnormality detection method may be, for example, to transmit an alarm when a ratio of the number of RX_EARLY or RX_LATE to the total number of RX_ON_TIME, RX_EARLY, and RX_LATE exceeds a threshold value. Namely, the abnormality detection method may be, for example, to transmit an alarm when a ratio of packets received outside a period of the reception window exceeds a threshold value. Alternatively, when the ratio of the number of RX_EARLY or RX_LATE to the number of RX_TOTAL exceeds a threshold value, it may be to transmit an alarm. Alternatively, when the ratio of the number of RX_EARLY or RX_LATE to the number of RX_ON_TIME exceeds a threshold value, it may be to transmit an alarm. The same applies to the number of packets counted by using the counter related to the C-Plane data.

Alternatively, the abnormality detection method may be to transmit an alarm when a ratio of the number of RX_ON_TIME to the total number of RX_ON_TIME, RX_EARLY, and RX_LATE is lower than a threshold value. Alternatively, the abnormality detection method may be to transmit an alarm when a ratio of the number of RX_ON_TIME to the number of RX_TOTAL is lower than a threshold value. Alternatively, the abnormality detection method may be to transmit an alarm when a ratio of the number of RX_ON_TIME to the number of RX_EARLY or RX_LATE is lower than a threshold value. The same applies to the number of packets counted by using the counter related to the C-Plane data.

Alternatively, the abnormality detection method may be to transmit an alarm when RX_ON_TIME exceeds a threshold value. Alternatively, the abnormality detection method may be to transmit an alarm when at least one of RX_EARLY and RX_LATE exceeds a threshold value. Alternatively, the abnormality detection method may be to transmit an alarm when at least one of RX_ON_TIME and RX_ON_TIME_C is lower than a threshold value or 0. The same applies to the number of packets counted by using the counter related to the C-Plane data.

Alternatively, the abnormality detection method may be to transmit an alarm when a packet relevant to RX_EARLY or RX_LATE is measured continuously for a number of times determined as a threshold value. The same applies to the number of packets counted by using the counter related to the C-Plane data.

A threshold value for transmitting an alarm may be a numerical value indicating a ratio, the number of packets, the number of times, or the like. Transmitting an alarm may be restated as transmitting an alarm signal or an alarm message.

Next, a control unit of the O-DU entity40determines whether a packet type to be measured is included in management data (S11). The control unit may be, for example, a processor or the like included in the O-DU entity40. The processing illustrated inFIG.5may be executed by a processor included in the O-DU entity40, which executes a program stored in a memory.

When determining that the packet type to be measured is included in the management data, the control unit of the O-DU entity40sets the packet type specified in the management data as a packet to be measured (S12). When determining that the packet type to be measured is not included in the management data, the control unit of the O-DU entity40sets the packet type determined as a default value, as the packet to be measured (S13). The default value may be stored in advance in a memory or the like in the O-DU entity40.

After step S12or S13, the control unit of the O-DU entity40determines whether an abnormality detection method is included in the management data (S14). When it is determined that the abnormality detection method is included in the management data, the control unit of the O-DU entity40sets the abnormality detection method specified in the management data (S15). When it is determined that the abnormality detection method is not included in the management data, the control unit of the O-DU entity40sets the abnormality detection method determined as a default value (S16). The default value may be stored in advance in a memory or the like in the O-DU entity40.

After step S15or S16, the control unit of the O-DU entity40determines whether the management data include a threshold value for transmitting an alarm (S17). When the control unit of the O-DU entity40determines that the management data include the threshold value for transmitting an alarm, the control unit sets the threshold value specified in the management data (S18). When the control unit of the O-DU entity40determines that the threshold value for transmitting an alarm is not included in the management data, the control unit sets a threshold value determined as a default value (S19). The default value may be stored in advance in a memory or the like in the O-DU entity40.

InFIG.5, a flow of processing in the case where the O-DU entity40receives the management data from the NMS50has been explained, but the same processing as inFIG.5is also performed in a case where the O-RU entity30receives the management data from the NMS50via the O-DU entity40. Therefore, detailed explanation of processing of setting management data in the O-RU entity30will be omitted.

Subsequently, a flow of alarm transmission processing in the O-RU entity30according to the second example embodiment is transmitted with reference toFIG.6. First, the reception unit11of the O-RU entity30receives a packet of C-Plane data and a packet of U-Plane data from the O-DU entity40(S20). Next, a control unit of the O-RU entity30generates statistical information regarding the received packet (S21). Specifically, the control unit of the O-RU entity30performs measurement of packets using RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL. The number of measured packets may be used as the statistical information. For example, the control unit of the O-RU entity30may count the packets by using all the counters, or may measure the packets by using only counters that count packets of the set packet type.

Next, the control unit of the O-RU entity30determines whether statistical information exceeds a threshold value in a preset abnormality detection method (S22). When the control unit of the O-RU entity30determines that the statistical information exceeds the threshold value, the transmission unit12of the O-RU entity30transmits an alarm (S23). For example, the transmission unit12transmits an alarm to the O-DU entity40. Alternatively, the transmission unit12may set a destination of the alarm as the NMS50and transmit the alarm to the NMS50via the O-DU entity40.

When the control unit of the O-RU entity30determines that the statistical information does not exceed the threshold value, the processing of step S20and subsequent steps is repeated.

InFIG.6, a flow of the alarm transmission processing in the O-RU entity30has been explained, but the O-DU entity40also executes the same alarm transmission processing as inFIG.6. For example, in step S20ofFIG.6, the O-DU entity40receives a packet of C-Plane data and a packet of U-Plane data from the O-RU entity30. In step S23, the O-DU entity40transmits an alarm to the NMS50. Other processing of the alarm transmission processing of the O-DU entity40is the same as that of the O-RU entity30, and thus a detailed explanation thereof will be omitted.

As described above, the O-RU entity30and the O-DU entity40use RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL and generate statistical data regarding the received packets. Further, the O-RU entity30and the O-DU entity40transmit an alarm when the statistical information exceeds a threshold value in a preset abnormality detection method. The O-RU entity30and the O-DU entity40transmit an alarm to an apparatus other than the own apparatus. Therefore, an administrator or the like of the NMS50can receive the statistical information from the O-RU entity30or the O-DU entity40without actively acquiring the statistical information generated in the O-RU entity30or the O-DU entity40. As a result, management loads of the O-RU entity30and the O-DU entity40in the administrator or the like of the NMS50can be reduced.

Third Example Embodiment

Next, statistical information used in a third example embodiment will be explained. In the third example embodiment, RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, or RX_ERR_DROP is used, thereby measuring the number of packets. RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, or RX_ERR_DROP is a definition of counters defined in the O-RAN Alliance.

RX_CORRUPT counts the number of packets that have been corrupted out of packets that have arrived at the O-RU entity30or the O-DU entity40within the reception window. The corrupted packet may be, for example, a packet in which an incorrect value is set in a header of the packet, or may be a packet including a protocol error. Among packets in which an incorrect value is set in the header of the packet, a packet in which an incorrect sequence ID is set may be counted by using RX_SEQID_ERR, which will be explained later. The number of corrupted packets may be acquired by measuring a packet of C-Plane data, measuring a packet of the U-Plane data, and measuring without distinguishing between the C-Plane data and U-Plane data.

RX_DUPL counts the number of duplicated packets among the packets that have arrived at the O-RU entity30or the O-DU entity40within the reception window.

RX_SEQID_ERR counts the number of packets having an error related to a sequence ID among the packets of the U-Plane data that have arrived at the O-RU entity30or the O-DU entity40within the reception window. An error related to the sequence ID is that an erroneous sequence ID is set in the packet, for example, when a value set in a sequence ID field of the packet header is not a consecutive value from the sequence ID of the packet received last time.

RX_SEQID_ERR_C counts the number of packets having an error related to the sequence ID, among the packets of the C-Plane data that have arrived at the O-RU entity30or the O-DU entity40within the reception window.

RX_ERR_DROP counts the number of packets discarded in the O-RU entity30or the O-DU entity40, among the packets of the C-Plane data or the U-Plane data that have arrived at the O-RU entity30or the O-DU entity40. The packet counted in RX_ERR_DROP may be a packet that has arrived in the reception window or may be a packet that has arrived outside the reception window.

The following will explain an abnormality detection method when RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, or RX_ERR_DROP is used as the statistical data. In this case, the abnormality detection method may be, for example, to transmit an alarm when a ratio of the number of RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, or RX_ERR_DROP to the number of RX_TOTAL exceeds a threshold value.

Alternatively, the abnormality detection method may be to transmit an alarm when a ratio of the number of RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, or RX_ERR_DROP to the number of RX_ON_TIME exceeds a threshold value.

Alternatively, the abnormality detection method may be to transmit an alarm when at least one of RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, and RX_ERR_DROP exceeds a threshold value.

Alternatively, the abnormality detection method may be to transmit an alarm when RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, or a packet relevant to RX_ERR_DROP is measured continuously by the number of times determined as a threshold value.

As explained above, in the third example embodiment, the O-RU entity30or the O-DU entity40can transmit an alarm in response to the number of packets including an error. As a result, management loads of the O-RU entity30and the O-DU entity40in an administrator of an NMS50or the like can be reduced as in the second example embodiment.

Fourth Example Embodiment

Next, a configuration example of a communication system according to a fourth example embodiment will be explained with reference toFIG.7.FIG.3illustrates an example in which only one transmission path61exists as a transmission path for transmitting C-Plane data and U-Plane data, butFIG.7illustrates a configuration in which the C-Plane data and the U-Plane data are transmitted via a plurality of transmission paths.

As illustrated inFIG.7, between an O-RU entity30and an O-DU entity40, there exist transmission paths61_1to61_n(n is an integer of two or more) as transmission paths for transmitting the C-Plane data and the U-Plane data. Furthermore, a transmission path62exists as a transmission path for transmitting M-Plane data. In other words, between the O-RU entity30and the O-DU entity40, there exist a plurality of fronthauls for transmitting C-Plane data and U-Plane data, and a fronthaul for transmitting M-Plane data. Alternatively, the transmission path for transmitting the M-Plane data may be shared with any one of the transmission paths61_1to61_nfor transmitting the C-Plane data and the U-Plane data. In short, any one of the transmission paths61_1to61_nfor transmitting the C-Plane data and the U-Plane data may transmit the M-Plane data.

The O-RU entity30or the O-DU entity40may generate statistical data by using at least one of RX_ON_TIME, RX_ON_TIME_C, RX_EARLY, RX_EARLY_C, RX_LATE, RX_LATE_C, and RX_TOTAL for each transmission path, i.e., for each fronthaul. Further, the O-RU entity30or the O-DU entity40may generate the statistical data by using at least one of RX_CORRUPT, RX_DUPL, RX_SEQID_ERR, RX_SEQID_ERR_C, and RX_ERR_DROP for each transmission path.

Alternatively, the O-RU entity30or the O-DU entity40may collectively generate the statistical data by using RX_ON_TIME or the like for packets transmitted on the transmission paths61_1to61_n.

The O-RU entity30or the O-DU entity40may implement the abnormality detection method explained in the second or third example embodiment for each transmission path, and determine whether the statistical information exceeds a threshold value. When the statistical information exceeds the threshold value, the O-RU entity30transmits an alarm to the O-DU entity40or transmits an alarm to an NMS50via the O-DU entity40. The O-DU entity40sends an alarm to the NMS50when the statistical information exceeds the threshold value.

Alternatively, the O-RU entity30or the O-DU entity40may determine whether the statistical information generated by collectively generating the packets transmitted on the transmission paths61_1to61_nexceeds a threshold value.

InFIG.7, it has been explained that a plurality of physically different transmission paths are used in order to transmit C-Plane data and U-Plane data between the O-RU entity30and the O-DU entity40. Herein, the plurality of transmission paths used for transmitting the C-Plane data and the U-Plane data may be a plurality of logical transmission paths set in one physical transmission path. For example, a plurality of logical transmission paths identified by using a port identifier may be set in one physical transmission path. For example, a logical transmission path may be identified by using a pair of port identifiers set in each of the O-RU entity30and the O-DU entity40.

In addition, a plurality of logical transmission paths identified by using an extended Antenna carrier-identification/identifier (eaxc-id) may be set in one physical transmission path. The eaxc-id includes RU_Port_ID, DU_Port_ID, BandSector_ID, and a CC_ID. RU_Port_ID is a port identifier of the O-RU entity30and DU_Port_ID is a port identifier of the O-DU entity40. BandSector_ID is an identifier of a band sector, and CC_ID is an identifier of a component carrier. Eaxc-id is determined in the O-RAN fronthaul specifications.

The O-RU entity30or the O-DU entity40may implement the abnormality detection method explained in the second or third example embodiment for each logical transmission path, and determine whether the statistical information exceeds a threshold value.

As explained above, the O-RU entity30and the O-DU entity40can implement the abnormality detection method explained in the second or third example embodiment for each of a plurality of physically different transmission paths or a plurality of logically different transmission paths. By causing the O-RU entity30or the O-DU entity40to autonomously transmit abnormal conditions related to a plurality of transmission paths to other apparatuses, it is possible to reduce administrative loads of an administrator that increases as the number of transmission paths increases.

Fifth Example Embodiment

Next, a configuration example of a communication system according to the fourth example embodiment will be explained with reference toFIG.8. In the communication system inFIG.8, a transmission path62_2for transmitting M-Plane data is added between an NMS50and an O-RU entity30in the communication system inFIG.3. In short, the O-RU entity30transmits the M-Plane data to an O-DU entity40via a transmission path621, and transmits the M-Plane data to the NMS50via the transmission path62_2.

In the communication system illustrated inFIG.8, the O-RU entity30transmits an alarm to the NMS50not via the O-DU entity40. Accordingly, even when an abnormality occurs in a transmission path between the O-RU entity30and the O-DU entity40, the NMS50can receive an alarm from the O-RU entity30. As a result, an administrator can detect the abnormality between the O-RU entity30and the O-DU entity40at an early stage.

Also in the communication system inFIG.8, as explained in the fourth example embodiment, a plurality of transmission paths may be set between the O-RU entity30and the O-DU entity40in order to transmit C-Plane data and U-Plane data.

Sixth Example Embodiment

Next, a configuration example of a communication system according to a sixth example embodiment will be explained with reference toFIG.9. The communication system inFIG.9has a configuration in which a Fronthaul Multiplexer (FHM)80is added to the communication system inFIG.8. The FHM80copies C-Plane data and U-Plane data received from an O-DU entity40and transmits them to a plurality of O-RU entities30. Further, the FHM80combines the C-Plane data and the U-Plane data received from each of the O-RU entities30, and transmits the combined data to the O-DU entity40.

The O-RU entity30transmits the C-Plane data and the U-Plane data to and from the FHM80via a transmission path711. Similarly toFIG.8, the O-RU entity30transmits the management data to the O-DU entity40and an NMS50via a transmission path62_1and a transmission path62_2.

The O-DU entity40transmits the C-Plane data and the U-Plane data to and from the FHM80via a transmission path71_2. The O-DU entity40transmits management data to and from the FHM80via the transmission path72_1. In the transmission path721, the management data may be transmitted as M-Plane data.

The NMS50transmits the management data to and from the FHM80via a transmission path72_2. In addition, the NMS50may transmit management data to and from the O-DU entity40not via the FHM80, as inFIG.8.

Similarly to the O-RU entity30and the O-DU entity40, the FHM80generates statistical information and performs abnormality detection. When an abnormality is detected, the FHM80transmits an alarm to the NMS50or the O-DU entity40.

In the communication system illustrated inFIG.9, in a configuration including the FHM80, the FHM80transmits an alarm to the O-DU entity40or the NMS50. Accordingly, an administrator can detect an abnormality occurring in the FHM80, in addition to the abnormalities occurring in the O-RU entity30and the O-DU entity40.

FIG.10is a block diagram illustrating a configuration example of the RU apparatus10, the DU apparatus20, the O-RU entity30, the O-DU entity40, the NMS50, and the FHM80(hereinafter, referred to as the RU apparatus10or the like). Referring toFIG.10, the RU apparatus10and the like include a network interface1201, a processor1202, and a memory1203. The network interface1201may be used for communicating with other network nodes. The network interface1201may include, for example, a network interface card (NIC) compliant with IEEE 802.3 series.

The processor1202reads and executes software (a computer program) from the memory1203and performs processing of the RU apparatus10and the like explained with reference to a flowchart in the above-described example embodiment. The processor1202may be, for example, a microprocessor, an MPU, or a CPU. The processor1202may include a plurality of processors.

The memory1203is constituted of a combination of a volatile memory and a non-volatile memory. The memory1203may include a storage located remotely from the processor1202. In this case, the processor1202may access the memory1203via Input/Output (I/O) interfaces, which are not illustrated.

In the example ofFIG.10, the memory1203is used for storing software modules. The processor1202reads these software modules from the memory1203and executes the software modules, thereby enabling to perform the processing of the RU apparatus10and the like explained in the above-described example embodiments.

As explained with reference toFIG.10, each of the processors included in the RU apparatus10and the like in the above-described example embodiments executes one or a plurality of programs including instructions for causing a computer to perform the algorithm explained with reference to the drawings.

In the examples described above, the program may be stored and supplied to a computer by using various types of non-transitory computer-readable media. The non-transitory computer-readable media include various types of tangible storage media. Examples of the non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, and hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), Read Only Memory (CD-ROM), CD-R, CD-R/W, and semi-conductor memory (e.g., mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flash ROM, Random Access Memory (RAM)). The program may also be supplied to the computer by various types of transitory computer-readable media. Examples of the transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable medium can supply the program to a computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

The present disclosure is not limited to the above-described example embodiments, and can be appropriately modified without departing from the scope of the present disclosure.

Some or all of the above-described example embodiments may be described as the following supplementary notes, but are not limited thereto.

An RU apparatus including:a reception unit configured to receive a packet from a distributed unit (DU) apparatus configured to execute processing of a higher-level layer than a layer to be executed by a remote unit (RU) apparatus among communication functions of a base station that are divided into a plurality of layers; anda transmission unit configured to transmit an alarm signal to the DU apparatus or a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

The RU apparatus according to supplementary note 1, wherein statistical information regarding the packet is information indicating that an abnormality occurs in communication with the DU apparatus.

The RU apparatus according to supplementary note 2, wherein statistical information regarding the packet is information regarding a packet received in a period different from a reception window being a period in which the packet transmitted from the DU apparatus can be normally received.

The RU apparatus according to supplementary note 3, wherein the transmission unit is configured to transmit the alarm signal when the number of packets received in a period different from the reception window exceeds a predetermined threshold value.

The RU apparatus according to supplementary note 3, wherein the transmission unit is configured to transmit the alarm signal when a ratio of the number of packets received in a period different from the reception window to all packets received in a period including the reception window exceeds a predetermined threshold value.

The RU apparatus according to supplementary note 2, wherein statistical information regarding the packet is information regarding a packet including an error.

The RU apparatus according to supplementary note 6, wherein the transmission unit is configured to transmit the alarm signal when the number of packets including the error or a ratio related to the number of packets including the error exceeds a predetermined threshold value.

The RU apparatus according to any one of supplementary notes 1 to 7, wherein the reception unit is configured to receive the predetermined criterion from the DU apparatus or the management apparatus.

A DU apparatus including:a reception unit configured to receive a packet from an RU apparatus configured to execute processing of a lower-level layer than a layer to be executed by a DU apparatus among communication functions of a base station that are divided into a plurality of layers; anda transmission unit configured to transmit an alarm signal to a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

The DU apparatus according to supplementary note 9, wherein statistical information regarding the packet is information indicating that an abnormality occurs in communication with the RU apparatus.

The DU apparatus according to supplementary note 10, wherein statistical information regarding the packet is information regarding a packet received in a period different from a reception window being a period in which the packet transmitted from the RU apparatus can be normally received.

The DU apparatus according to supplementary note 11, wherein the transmission unit is configured to transmit the alarm signal when the number of packets received in a period different from the reception window exceeds a predetermined threshold value.

The DU apparatus according to supplementary note 11, wherein the transmission unit is configured to transmit the alarm signal when a ratio of the number of packets received in a period different from the reception window to all packets received in a period including the reception window exceeds a predetermined threshold value.

The DU apparatus according to supplementary note 10, wherein statistical information regarding the packet is information regarding a packet including an error.

The DU apparatus according to supplementary note 14, wherein the transmission unit is configured to transmit the alarm signal when the number of packets including the error or a ratio related to the number of packets including the error exceeds a predetermined threshold value.

The DU apparatus according to any one of supplementary notes 9 to 15, wherein the reception unit is configured to receive the predetermined criterion from the management apparatus.

The DU apparatus according to any one of supplementary notes 9 to 16, wherein the transmission unit transmits the predetermined criterion to the RU apparatus.

A communication system including:an RU apparatus configured to execute a part of layer processing among communication functions of a base station that are divided into a plurality of layers;a DU apparatus configured to transmit and receive a packet to and from the RU apparatus, and execute processing of a higher-level layer than a layer to be executed by the RU apparatus; anda management apparatus configured to manage a network including the RU apparatus and the DU apparatus, whereinat least one of the RU apparatus and the DU apparatus is configured to transmit an alarm signal to the management apparatus when statistical information regarding the received packet satisfies a predetermined criterion, andthe management apparatus transmits the predetermined criterion to at least one of the RU apparatus configured to transmit the alarm signal and the DU apparatus configured to transmit the alarm signal.

The communication system according to supplementary note 18, wherein statistical information regarding the packet is information indicating that an abnormality occurs in communication with the DU apparatus.

A communication method being executed in an RU apparatus, the communication method including:receiving a packet from a distributed unit (DU) apparatus configured to execute processing of a higher-level layer than a layer to be executed by a remote unit (RU) apparatus among communication functions of a base station that are divided into a plurality of layers; andtransmitting, when statistical information regarding the received packet satisfies a predetermined criterion, an alarm signal to the DU apparatus or a management apparatus configured to manage a network.

A communication method being executed in a DU apparatus, the communication method including:receiving a packet from an RU apparatus configured to execute processing of a lower-level layer than a layer to be executed by a DU apparatus among communication functions of a base station that are divided into a plurality of layers; andtransmitting, when statistical information regarding the received packet satisfies a predetermined criterion, an alarm signal to a management apparatus configured to manage a network.

A program causing a computer to execute:receiving a packet from a distributed unit (DU) apparatus configured to execute processing of a higher-level layer than a layer to be executed by a remote unit (RU) apparatus among communication functions of a base station that are divided into a plurality of layers; andtransmitting an alarm signal to the DU apparatus or a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

A program causing a computer to execute:receiving a packet from an RU apparatus configured to execute processing of a lower-level layer than a layer to be executed by a DU apparatus among communication functions of a base station that are divided into a plurality of layers; andtransmitting an alarm signal to a management apparatus configured to manage a network when statistical information regarding the received packet satisfies a predetermined criterion.

The present disclosure is not limited to the above-described example embodiments, and can be appropriately modified without departing from the scope of the present disclosure.

REFERENCE SIGNS LIST