Base station device, control method, and program for controlling wave stop in shared frequency band

Abstract

To more reliably execute wave stop when a base station in a radio communication system capable of using a shared frequency band should perform the wave stop.SOLUTION: A base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system is configured to: receive information indicating whether or not to stop transmission of a radio wave using the frequency band from a control device included in the wireless communication system; control so as to stop the transmission of the radio wave using the frequency band and release the stop based on the reception of the information or another predetermined factor different from the reception of the information; confirm that stop information indicating that the transmission of the radio wave using the frequency band should be stopped is not notified from the control device before the stop is released based on elimination of the other predetermined factor after performing the stop based on the other predetermined factor; and release the stop when it is confirmed that the stop information is not notified, and control so as to maintain the stop when it is not confirmed that the stop information is not notified.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a technique for controlling the suspension of radio waves transmitted by a base station in a wireless communication system that can use a shared frequency band. [Background technology]

[0002] In order to improve frequency utilization efficiency, there is a mechanism for sharing a specific frequency band among multiple wireless systems. For example, in Japan, television broadcasting, public service radio, and cellular communication systems may share the 2.3 GHz band. When a cellular communication system uses a shared frequency band, it may be required to stop (shut off) radio waves transmitted by the base station when another wireless system uses that frequency band. Patent Document 1 describes a technology for estimating the position of a wireless station to avoid radio wave interference in a shared frequency band. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-143207 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a technique that enables a base station in a wireless communication system that can use a shared frequency band to more reliably stop transmitting when the base station needs to stop transmitting. [Means for solving the problem]

[0005] A control device according to one aspect of the present invention is a base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, and comprises: a receiving means for receiving information indicating whether or not the transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; a control means for controlling the suspension of the transmission of radio waves using the frequency band and the cancellation of the suspension based on the reception of the information or another predetermined factor different from the reception of the information; and a confirmation means for confirming that, after performing the suspension based on the other predetermined factor, the control device has not notified the control device of suspension information indicating that the transmission of radio waves using the frequency band should be stopped before canceling the suspension based on the resolution of the other predetermined factor, and the control means cancels the suspension if it is confirmed that the suspension information has not been notified, and controls to maintain the suspension if it is not confirmed that the suspension information has not been notified. [Effects of the Invention]

[0006] According to the present invention, when a base station in a wireless communication system that can use a shared frequency band needs to stop transmitting, the base station can more reliably stop transmitting. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system. [Figure 2] FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station. [Figure 3] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station. [Figure 4] 10 is an example of a flowchart showing an operation flow of a base station. [Figure 5] FIG. 4 is a diagram illustrating an example of a sequence executed between a base station and a first control device. [Figure 6] FIG. 4 is a diagram illustrating an example of a sequence executed between a base station and a first control device. [Figure 7]FIG. 4 is a diagram illustrating an example of a sequence executed between a base station and a first control device. [Figure 8] 10 is an example of a flowchart showing an operation flow of a base station. [Figure 9] FIG. 4 is a diagram illustrating an example of a sequence executed between a base station and a first control device. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Furthermore, the same reference numerals are used for the same or similar components, and redundant explanations will be omitted.

[0009] (System Configuration) FIG. 1 shows an example of the configuration of a wireless communication system 100 according to this embodiment. The wireless communication system 100 is, for example, a cellular communication system conforming to the cellular communication standard of the Third Generation Partnership Project (3GPP (registered trademark)). However, the present invention is not limited to this, and the following discussion can be applied to a wireless communication system conforming to any wireless communication standard. The wireless communication system 100 includes, for example, a base station 111, a first control device 121, and a second control device 122. The base station 111 is connected to the first control device 121 and the second control device 122 via a wired network. The base station 111 may be connected to the first control device 121 and the second control device 122 via a wireless network. The first control device 121 is connected to a frequency sharing management device 131 via a wired network or a wireless network. The frequency sharing management device 131 may be included in the wireless communication system 100 or may be located outside the wireless communication system 100. In other words, the operator of the wireless communication system 100 and the operator of the frequency sharing management device 131 may be different. Although Figure 1 shows a configuration in which one base station 111, one first control device 121, one second control device 122, and one frequency sharing management device 131 are deployed, two or more of each device may be deployed, or two or more of the devices may be configured as one device.

[0010] The base station 111 exchanges radio signals with one or more user terminals (not shown) via a wireless medium. The base station 111 may be, for example, a next generation Node B (gNB) or an evolved Node B (eNB). The user terminal may also be referred to as User Equipment (UE). The user terminal may be, for example, a smartphone, a mobile phone, a personal computer, a tablet terminal, a wearable terminal, an IoT (Internet of Things) terminal, or the like.

[0011] The first control device 121 is a device that configures, manages, controls, etc., network devices such as the base station 111 that configure the wireless communication system 100. The first control device 121 may be, for example, an Element Management System (EMS). The EMS may provide the wireless communication system 100 with functions for performing network fault management, configuration management, performance management, security management, etc., in cooperation with, for example, a Network Management System (NMS) that comprehensively manages network devices. The EMS may perform, for example, collection of statistical information regarding communications in a cell configured by the base station 111, base station configuration such as setting and changing parameters for the operation of the base station 111, and base station control such as call control of the base station during congestion and blocking control for maintenance. Note that the first control device 121 may be a network device other than an EMS as long as it is a device that can configure and control the base station. Signals exchanged between the first control device 121 and the base station 111 may be called M-plane (management) signals.

[0012] The second control device 122 is a device that controls the base station 111 and user terminals to connect to and operate in the wireless communication system. For example, the second control device 122 may be a Mobility Management Entity (MME) in a mobile communication system based on the Long Term Evolution (LTE) standard or an Access and Mobility Management Function (AMF) in a fifth-generation (5G) mobile communication system. The second control device 122 may be a network device other than an MME or an AMF, and may be any of the network devices included in an Evolved Packet Core (EPC) or a 5G Core Network (5GC) that provide predetermined functions to the network. The second control device 122 may provide the wireless communication system 100 with functions such as management of network registration of user terminals, mobility management, authentication, and session management. Signals exchanged between the second control device 122 and the base station 111 and user terminals may be called C-plane (control) signals.

[0013] The base station 111 performs wireless communication using a predetermined frequency band. For example, the base station 111 may perform wireless communication using frequency bands allocated to cellular communication systems, such as the 700 MHz band, 800 MHz band, 900 MHz band, 1.5 GHz band, 1.7 GHz band, 2 GHz band, 2.5 GHz band, 3.4 GHz band, 3.5 GHz band, 3.7 GHz band, 4.5 GHz band, and 28 GHz band. Meanwhile, the base station 111 may be able to use frequencies allocated to other wireless systems. For example, there is a mechanism for multiple wireless systems to flexibly share frequencies, taking into account the geographical and temporal operational status of existing wireless systems. This mechanism may be called dynamic frequency sharing. In dynamic frequency sharing, a primary user of a predetermined frequency band submits an operation plan for that frequency band. If a base station used by a secondary user is likely to cause interference to the primary user's wireless system within a predetermined temporal and geographical range of the primary user's operation plan, the base station is instructed to stop transmitting. This allows frequencies to be shared geographically and temporally between the primary user and the secondary user. A primary user is, for example, a broadcasting company. A secondary user is, for example, a mobile phone company. The primary user or secondary user may be another type of company. The primary user's operation plan may include the frequency to be used, the location, the date and time, etc. For example, the frequency band that is the target of dynamic spectrum sharing may be the 2.3 GHz band. The frequency band that is the target of dynamic spectrum sharing may also be another frequency band.

[0014] The processing for sharing frequencies in dynamic spectrum sharing may be executed by the spectrum sharing management device 131. The processing for sharing frequencies may be, for example, allocating frequencies to secondary users or issuing instructions to shut down transmissions. For example, the spectrum sharing management device 131 identifies base stations that may cause interference to the primary user based on the operation plan received from the primary user. The spectrum sharing management device 131 then determines the date, time, and location when the secondary user is not permitted to use the base station. Based on the determination results, the spectrum sharing management device 131 may instruct the secondary user to shut down the base station. The secondary user shuts down the base station based on the instruction from the spectrum sharing management device 131 and notifies the spectrum sharing management device 131 that the shutdown is complete. The spectrum sharing management device 131 may notify the primary user that the shutdown is complete. Note that when the spectrum sharing management device 131 becomes able to lift the suspension of the base station that it instructed to shut down, it may notify the secondary user that it may lift the suspension. Furthermore, when issuing an instruction to stop transmission, the frequency sharing management device 131 may also notify the period for which transmission should be stopped. In this case, the frequency sharing management device 131 does not need to notify the cancellation of the suspension. When it becomes possible to cancel the suspension based on the instruction from the frequency sharing management device 131, the secondary user will cancel the suspension of the base station.

[0015] When a predetermined shared frequency band included in the target of dynamic frequency sharing is used in the wireless communication system of the secondary user, the first control device 121 may execute control of the base station 111 based on an instruction from the frequency sharing management device 131 regarding whether the shared frequency band is available. For example, the first control device 121 may notify the frequency sharing management device 131 of the frequency used by the base station 111, the location, date and time, the base station identifier, etc. Furthermore, the first control device 121 may receive an instruction from the frequency sharing management device 131 to shut down the transmission of the base station 111. The instruction from the frequency sharing management device 131 may include the identifier of the base station that is to shut down the transmission, the date and time when the shut down should start, etc. Note that the instruction from the frequency sharing management device 131 may also include the frequency band that is to be shut down, the date and time when the shut down should be lifted, etc. Then, based on the instruction from the frequency sharing management device 131, the first control device 121 may transmit information to the base station 111 indicating that it should shut down the transmission of radio waves (stop transmitting radio waves). When the base station 111 receives information indicating that it should stop transmitting from the first control device 121, it may stop transmitting signals using a predetermined frequency band. On the other hand, when it becomes possible to resume communications using the predetermined shared frequency band, i.e., when it is possible to lift the suspension, the first control device 121 may send a permission notice to the base station 111 indicating that it is permitted to transmit radio waves using the predetermined shared frequency band. When the base station 111 receives the permission notice from the first control device 121, it may lift the suspension and resume transmitting radio waves using the predetermined shared frequency band. In dynamic spectrum sharing, the application by the primary user may be automated using a system, or may be partially input by an operator. For example, the operation plan by the primary user may be accepted by an operator of the spectrum sharing management device 131, and the operator may input some information included in the operation plan and the usage application into the spectrum sharing management device 131. The input information may be automatically notified from the frequency sharing management device 131 to the first control device 121, or may be notified by the operator of the frequency sharing management device 131 to the operator of the wireless communication system 100, and the information regarding the outage may be input to the first control device 121 by the operator of the wireless communication system 100.

[0016] As described above, the base station 111 in a wireless communication system using a shared frequency band stops transmitting when it receives information indicating that radio wave transmission should be stopped from the first control device 121 based on an instruction from the frequency sharing management device 131. Meanwhile, the base station 111 may also stop transmitting due to other predetermined factors. For example, the base station 111 may stop transmitting when communication with the second control device 122 is disconnected. As an example, the base station 111 provides wireless access services to user terminals while exchanging control information with the second control device 122. During this time, the base station 111 may perform alive monitoring to check the operating status of the second control device 122. For example, the base station 111 may transmit a predetermined signal to the second control device 122 at a predetermined period and determine that the second control device 122 is operating normally by receiving a response thereto. Such a predetermined signal for alive monitoring may be called a heartbeat signal. At this time, if there is no response from the second control device 122, the base station 111 may stop transmitting radio signals in its cell as a fail-safe measure. That is, the base station 111 may also stop transmitting in this case. The base station 111 may continue transmitting a predetermined signal for alive monitoring to the second control device 122 even during the suspension of transmission, and upon receiving a response from the second control device 122, may cancel the suspension of transmission and resume transmitting radio signals. In this way, the base station 111 may autonomously suspend transmission based on a predetermined factor, and may autonomously cancel the suspension of transmission when the predetermined factor is resolved.

[0017] When the base station 111 resumes the radio wave suspension that it performed due to a predetermined cause after the cause is resolved, interference may occur in the shared frequency band. For example, assume that the frequency sharing management device 131 issues a radio wave suspension instruction to the first control device 121 while the base station 111 is suspending radio waves. If the base station 111 successfully receives information from the first control device 121 indicating that it should stop transmitting radio waves to the base station 111, the base station 111 may continue the radio wave suspension even after the predetermined cause is resolved. On the other hand, the information indicating that it should stop transmitting radio waves may not reach the base station 111 due to a disconnection of communication between the base station 111 and the first control device 121, etc. If the information from the first control device 121 is not correctly received, the base station 111 may transmit radio signals using the shared frequency band even when use of the shared frequency band is not permitted. This may result in interference with the primary user's radio system. Note that if the base station 111 is suspending transmission based on another predetermined factor at the timing when it should suspend transmission based on an instruction from the frequency sharing management device 131, the operator of the wireless communication system cannot determine whether the information from the first control device 121 has been successfully received by the base station 111. For example, if the base station 111 suspends transmission after transmitting information from the first control device 121, the operator of the wireless communication system can confirm that the information has been successfully received by the base station 111. However, if information is transmitted from the first control device 121 while the base station 111 is suspending transmission, it cannot be confirmed in advance whether the base station 111 will continue the suspension when the other predetermined factor is resolved. In this way, there is a possibility that the base station 111 will cancel the suspension and resume communication using the shared frequency band at the timing when it should continue the suspension.

[0018] In consideration of these circumstances, in the present embodiment, when the base station 111 suspends radio waves based on a predetermined factor other than receiving information indicating that radio wave transmission should be suspended from the first control device 121, the base station 111 confirms that the control device 121 has not notified it of suspension information indicating that radio wave transmission using the shared frequency band should be suspended before the base station 111 resumes the suspension based on the resolution of the other predetermined factor. For example, the base station 111 may transmit a message to the first control device 121 inquiring whether or not it is permitted to transmit radio waves using the shared frequency band, and may perform this confirmation by receiving a response to the message. The base station 111 then resumes the suspension if it is confirmed that the first control device 121 has not notified it of suspension information, and maintains the suspension if it is not confirmed that the suspension information has not been notified. By operating in this manner, even if the base station 111 does not successfully receive information indicating that radio wave transmission should be suspended from the first control device 121 during the period in which the base station 111 suspended radio waves, the base station 111 can avoid resuming the suspension and starting communication using the shared frequency band during the period in which the base station 111 should suspend radio waves. This makes it possible to avoid interference with the wireless system of the primary user.

[0019] (Circuit configuration) An example of the configuration of the base station 111 described above will be described. FIG. 2 is a diagram showing the hardware configuration of the base station 111. In one example, the base station 111 includes a processor 201, a ROM 202, a RAM 203, a storage device 204, and a communication circuit 205. The processor 201 is a computer including one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). The processor 201 reads and executes programs stored in the ROM 202 or the storage device 204, thereby executing the overall processing of the device and each of the above-mentioned processes. The ROM 202 is a read-only memory that stores information such as programs and various parameters related to the processing executed by the base station 111. The RAM 203 functions as a workspace when the processor 201 executes a program, and is also a random access memory that stores temporary information. The storage device 204 is, for example, a removable external storage device. The communication circuit 205 is, for example, configured to include a circuit for communicating with other devices.

[0020] (Functional configuration) Fig. 3 is a diagram showing an example of the functional configuration of the base station 111. The base station 111 is configured to include, as its functions, an information receiving unit 301, a wave-stop control unit 302, and a status checking unit 303, for example. Fig. 3 shows the functional configuration of the base station 111 of this embodiment, and omits, for example, the general configuration of a base station. Note that these functional units can be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204 and controlling the communication circuit 205 as necessary. However, the present invention is not limited to this, and for example, dedicated hardware for realizing each function may be provided.

[0021] The information receiving unit 301 receives, from the first control device 121, wave suspension instruction information indicating whether or not to suspend transmission of radio waves using the shared frequency band. The wave suspension control unit 302 controls the suspension and lifting of the suspension of radio waves using the shared frequency band. For example, the wave suspension control unit 302 may suspend transmission of radio waves based on receiving, from the first control device 121, information indicating whether or not to suspend transmission of radio waves using the shared frequency band, and may lift the suspension based on receiving a permission notice indicating that transmission of radio waves using the shared frequency band is permitted. The wave suspension control unit 302 may suspend transmission of radio waves based on a predetermined factor other than receiving, from the first control device 121, information indicating whether or not to suspend transmission of radio waves using the shared frequency band, and may lift the suspension based on the resolution of the predetermined factor. Furthermore, the wave suspension control unit 302 may lift the suspension if it is confirmed that no suspension instruction information has been notified from the first control device 121 before lifting the suspension, and may maintain the suspension if it is not confirmed that no suspension instruction information has been notified. The state confirmation unit 303 confirms that no wave-shutoff instruction information has been notified from the first control device 121. For example, before canceling the wave-shutoff, the state confirmation unit 303 can confirm that no wave-shutoff instruction information has been notified by transmitting a message to the first control device 121 inquiring whether or not it is OK to transmit radio waves using the shared frequency band, and receiving a response to this message from the first control device 121. Furthermore, the state confirmation unit 303 can confirm that no wave-shutoff instruction information has been notified by monitoring the operating state of the first control device 121.

[0022] (Processing flow) (Processing example 1) FIG. 4 shows an example of a flowchart of the operation of the base station 111, which communicates using a shared frequency band in this processing example, when the base station 111 resumes the suspension of radio waves from a suspended state. This operation can be performed when the base station 111 is suspending radio waves based on a predetermined factor other than receiving information (shutdown instruction information) from the first control device 121 indicating that radio wave transmission should be stopped. For example, the predetermined factor can be that the base station 111 does not receive a response within a predetermined period of time after transmitting a predetermined signal for alive monitoring to the second control device 122. The predetermined factor may be any other factor as long as it is a factor that allows the base station 111 to determine that radio waves should be suspended. Note that the base station 111 may suspend radio waves autonomously or based on an instruction from another network device. In this example, a case where the base station 111 autonomously suspends radio waves will be described. First, it is assumed that the base station 111 is suspending radio waves autonomously based on a predetermined factor other than the shutdown instruction information (S401). The base station 111 determines whether the cause of the outage has been resolved, and if the cause of the outage has been resolved (YES in S402), executes the process of S403, and if the cause of the outage has not been resolved (NO in S402), maintains the outage until the cause of the outage is resolved. For example, if the base station 111 transmits a predetermined signal for alive monitoring to the second control device 122 and does not receive a response within a predetermined period, the base station 111 can periodically retransmit the predetermined signal for alive monitoring to the second control device even during the outage, and can determine that the cause of the outage has been resolved if it receives a response.

[0023] When the cause of the wave outage is resolved (YES in S402), the base station 111 checks whether the first control device 121 has not notified it of stop instruction information indicating that the transmission of radio waves using the shared frequency band should be stopped (S403). In this example, the base station 111 transmits a message to the first control device 121 inquiring whether it is permitted to transmit radio waves using the shared frequency band. If the first control device 121 holds information indicating whether the base station 111 is permitted to transmit radio waves using the shared frequency band, the first control device 121 can respond to the base station 111 based on this information. For example, when the first control device 121 receives a wave outage instruction from the frequency sharing management device 131, the first control device 121 can hold information about the base station that should stop transmitting (such as an identifier that can uniquely identify the base station) until the instruction is lifted. Note that when the frequency sharing management device 131 issues a wave outage instruction specifying a period, the first control device 121 can hold a pair of information about the base station that should stop transmitting and the period for which the wave should be out. When the first control device 121 receives an instruction to lift the suspension from the frequency sharing management device 131, it can notify the base station that should lift the suspension and discard information about the base station that should shut down. Furthermore, when the first control device 121 receives an instruction to lift the suspension from the frequency sharing management device 131 that includes a suspension period, it can notify the base station that should lift the suspension based on the lapse of the period and discard information about the base station that should shut down. If the base station 111 that sent the message inquiring whether it is permitted to transmit radio waves using the shared frequency band is a base station that should shut down, the first control device 121 responds with suspension instruction information. Furthermore, if the base station 111 that sent the message inquiring whether it is permitted to transmit radio waves using the shared frequency band is not a base station that should shut down, the first control device 121 responds with a permission notification indicating that it is permitted to transmit radio waves using the shared frequency band. In addition, during the period from when base station 111 starts to shut down based on a specified factor other than receiving stop instruction information from first control device 121 until the other specified factor is resolved, if base station 111 receives stop instruction information from control device 121 and does not receive a permission notification from control device 121 indicating that it is permitted to transmit radio waves using a shared frequency band after the stop instruction information is notified, base station 111 can maintain the shut down until it receives a permission notification.

[0024] When the base station 111 receives a response including a permission notification from the first control device 121 (YES in S404 and YES in S405), the base station 111 cancels the suspension of transmission and resumes communication using the shared frequency band (S406). When the base station 111 receives a response including suspension instruction information from the first control device 121 (YES in S404 and NO in S405), the base station 111 maintains the suspension of transmission until it receives a permission notification from the first control device 121 (NO in S407). In this case, when it receives a permission notification from the first control device 121 (YES in S407), the base station 111 cancels the suspension of transmission and resumes communication using the shared frequency band (S406). On the other hand, when the base station 111 does not receive a response from the first control device 121 (NO in S404), it maintains the suspension of transmission and continues to retransmit the inquiry to the first control device 121.

[0025] FIG. 5 shows an example of a sequence between the base station 111 and the first control device 121 in this example. This sequence can be executed when the base station 111 is shutting down based on a predetermined factor other than receiving shutdown instruction information from the first control device 121. When the base station 111 detects that the factor for the shutdown has been resolved (S501), it transmits a message to the first control device 121 inquiring whether it is permitted to transmit radio waves using the shared frequency band (S502). The first control device 121 transmits a response based on information stored therein about the base station that should shut down (S503). For example, if the base station 111 is not a base station that should shut down, the first control device 121 transmits a response including a permission notification indicating that it is permitted to transmit radio waves using the shared frequency band. On the other hand, if the base station 111 is a base station that should shut down, the first control device 121 transmits a response including shutdown instruction information. Based on the response from the first control device 121, the base station 111 either cancels the suspension of transmission (S504) or maintains the suspension of transmission.

[0026] Thus, in this example, when the cause of the outage is resolved, base station 111 inquires of first control device 121 whether it is OK to transmit radio waves using the shared frequency band, and based on the response, it lifts or maintains the suspension. First control device 121 holds information about base stations that should suspend transmission in response to instructions from frequency sharing management device 131, and responds to base station 111 based on this information. With this configuration, when base station 111 lifts the suspension, it checks whether it is OK to lift the suspension in the shared frequency band, making it possible to avoid generating interference in the shared frequency band.

[0027] (Variation) In the above example, when the cause of the outage is resolved, the base station 111 inquires of the first control device 121 whether it is permitted to transmit radio waves using the shared frequency band. At this time, there are cases where a response from the first control device 121 cannot be received. For example, there are cases where a message from the base station 111 does not reach the first control device 121 or a response from the first control device 121 does not reach the base station 111 due to disconnection or congestion of the communication line between the base station 111 and the first control device 121. In this way, if the base station 111 cannot receive a response from the first control device 121, it cannot release the outage. As a result, a situation where wireless access services cannot be provided to user terminals may continue.

[0028] Therefore, the base station 111 may retransmit the inquiry using a predetermined timer. For example, when the cause of the outage is resolved and the base station 111 transmits a message to the first control device 121 inquiring whether it is permitted to transmit radio waves using the shared frequency band, the base station 111 starts the predetermined timer and waits for a response from the first control device 121. If the predetermined timer expires without receiving a response from the first control device 121, the base station 111 retransmits the message. At this time, the base station 111 may start the predetermined timer again. If the predetermined timer expires without receiving a response from the first control device 121, the base station 111 may retransmit the message again. On the other hand, if the base station 111 receives a response from the first control device 121 before the predetermined timer expires, the base station 111 releases or maintains the outage based on the response. The base station 111 may maintain the outage while waiting for a response from the first control device 121.

[0029] 6 shows an example of a sequence between the base station 111 and the first control device 121 when the base station 111 transmits a message to the first control device 121 inquiring whether it is permitted to transmit radio waves using the shared frequency band and does not receive a response to the message. Operations similar to those in FIG. 5 are assigned the same reference numerals and will not be described again. That is, when the cause of the outage is resolved (S501), the base station 111 transmits a message to the first control device 121 inquiring whether it is permitted to transmit radio waves using the shared frequency band and starts a predetermined timer (S601). If a response is not received from the first control device 121 before the timer expires, the base station 111 retransmits the message and starts the predetermined timer (S602). The base station 111 may continue to retransmit the message until it receives a response from the first control device 121 (S603, S604). When the base station 111 receives a response from the first control device 121 within the time limit of the predetermined timer (S503), it cancels the timer and cancels or maintains the suspension of transmission based on the received response (S504).

[0030] In this way, in this modification, after the cause of the outage is resolved, the base station 111 transmits a message to the first control device 121 inquiring whether it is OK to transmit radio waves using the shared frequency band, and continues to retransmit the message until it receives a response. This allows the base station 111 to reliably avoid causing interference to the primary user even if a situation arises in which the base station 111 cannot confirm whether it is OK to transmit radio waves using the shared frequency band due to disconnection or congestion of the communication line between the base station 111 and the first control device 121.

[0031] (Processing example 2) In the processing example 1, an example is described in which the base station 111 stops transmitting due to a factor other than receiving the stop instruction information from the first control device 121, and when the factor for the stop is resolved, it transmits a message to the first control device 121 inquiring whether it is OK to transmit radio waves using the shared frequency band. In this example, an example is described in which the base station 111, instead of or in addition to transmitting the message, performs alive monitoring of the first control device 121, and implicitly confirms that the first control device 121 has not notified the stop instruction information based on the fact that the first control device 121 has operated normally. That is, the base station 111 performs alive monitoring of the first control device 121 during the period in which it is stopping transmitting, and based on the fact that the first control device 121 has operated normally until the factor for the autonomous stop of the base station 111 is resolved, it can cancel the suspension without transmitting a message to the first control device 121 inquiring whether it is OK to transmit radio waves using the shared frequency band. With this configuration, it becomes possible to resume wireless access services without waiting for a response to an inquiry from the first control device 121 as to whether or not it is permissible to transmit radio waves using the shared frequency band.

[0032] FIG. 7 shows an example of a sequence between the base station 111 and the first control device 121 when the base station 111 stops transmission based on a predetermined factor and then resumes transmission based on the monitoring results of the first control device 121 when the predetermined factor is resolved. Operations similar to those in FIG. 5 are assigned the same reference numerals and will not be described again. Specifically, the base station 111 performs an autonomous transmission shutdown when a predetermined factor occurs (S701). After the base station 111 performs transmission shutdown, it transmits a signal to check the operating status of the first control device 121 (S702) and starts a predetermined timer. The first control device 121 responds to the signal received from the base station 111 (S703). By receiving a response from the first control device 121 before the predetermined timer expires, the base station 111 confirms that the first control device 121 is operating normally and that there is no problem with the communication line between the base station 111 and the first control device 121, and then stops the timer. At a predetermined cycle for checking the operating status of the first control device 121, the base station 111 again transmits a signal for checking the operating status of the first control device 121 (S704) and starts a predetermined timer. The first control device 121 responds to the signal received from the base station 111 (S705). If the base station 111 receives a response from the first control device 121 before the timer expires, the base station 111 stops the timer. The base station 111 periodically repeats this operation (S706, S707). Then, when the cause of the outage is resolved (S501), the base station 111 determines whether it has been confirmed that the first control device 121 was operating normally from the start of the outage to the resolution of the cause of the outage. If it is confirmed that the first control device 121 was operating normally, the base station 111 resumes the outage (S504). If the base station 111 does not confirm that the first control device 121 was operating normally during the period from the start of the outage to the resolution of the cause of the outage, the base station 111 may transmit a message to the first control device 121 after the cause of the outage is resolved, inquiring whether or not it is permitted to transmit radio waves using the shared frequency band. The base station 111 may maintain the outage until it receives a response to the message from the first control device 121.

[0033] In this way, in this example, the base station 111 does not explicitly check with the first control device 121 before lifting the suspension, but rather implicitly checks that suspension instruction information has not been notified from the first control device 121 based on the monitoring result of the operation state of the first control device 121, and then lifts the suspension. This allows the base station 111 to quickly resume wireless access service once the cause of the suspension is resolved.

[0034] (Processing example 3) In the processing example 1, the base station 111 stops transmitting due to a factor other than receiving the stop instruction information from the first control device 121, and when the factor for the stop is resolved, the base station 111 transmits a message to the first control device 121 inquiring whether or not it is OK to transmit radio waves using the shared frequency band. In this example, the base station 111 performs alive monitoring of the first control device 121 and stops transmitting based on the fact that it does not receive a response to the alive monitoring signal. That is, when the base station 111 is communicating using the shared frequency band, if a situation occurs in which communication between the base station 111 and the first control device 121 is disabled, the base station 111 may not receive the stop instruction information from the first control device 121. In this case, the radio waves transmitted by the base station 111 may continue to interfere with the wireless system of the primary user of the shared frequency band. Therefore, in this example, the base station 111 periodically transmits a signal for performing alive monitoring between the base station 111 and the first control device 121, and if it does not receive a response, the base station 111 stops transmitting. Then, the base station 111 maintains the stopped state until it receives a response from the first control device 121. This allows the base station 111 to keep the transmission stopped when it cannot be determined whether or not a stop transmission instruction or the like has been received from the frequency sharing management device 131, for example, and therefore makes it possible to avoid causing interference to the wireless system of the primary user of the shared frequency band.

[0035] Figure 8 shows an example of the flow of operations executed by the base station 111 in this example. Operations similar to those in Figure 4 are given the same reference numerals, and descriptions thereof will be omitted. This operation can be executed when the base station 111 starts communication using a shared frequency band. First, the base station 111 transmits a signal to the first control device 121 to confirm the operation status (S801). By receiving a response from the first control device 121 (YES in S802), the base station 111 can confirm that the first control device 121 is operating normally and that there is no problem with the communication line between the base station 111 and the first control device 121.

[0036] On the other hand, if the base station 111 does not receive a response from the first control device 121 (NO in S802), it autonomously shuts down transmission (S401). For example, the base station 111 may transmit a control signal to the first control device 121 requesting confirmation of the operation status, as in FIG. 7, and may also start a predetermined timer. The predetermined timer may be called an EMS Down determination timer. If the predetermined timer expires without receiving a response from the first control device 121, the base station 111 may autonomously shut down transmission. Note that if the predetermined timer expires without receiving a response from the first control device 121, the base station 111 may not immediately shut down transmission autonomously, but may instead retransmit a signal for confirming the operation status of the first control device 121 one or more times, and if the number of retransmissions exceeds a predetermined threshold, may autonomously shut down transmission. For example, if a response from the first control device 121 is temporarily not received due to congestion on the communication line between the base station 111 and the first control device 121, autonomously shutting down the transmission based on this may result in a situation in which the wireless access service to the user terminal is repeatedly stopped and resumed. In response to this, the base station 111 may autonomously shut down the transmission after performing a predetermined number of retransmissions, thereby avoiding such a situation in which the service is repeatedly stopped and resumed. The base station 111 may use, for example, an Internet Control Message Protocol (ICMP) Ping as a signal to check the operating status of the first control device 121. As an example, the base station 111 may send an ICMP Echo Request, and in response, the first control device 121 may return an ICMP Echo Reply. The signals used in the alive monitoring between the base station 111 and the first control device 121 are not limited to these, and any signal that allows the base station 111 to check the operating status of the first control device 121 may be used.

[0037] When the base station 111 stops transmitting based on the fact that it has not received a response from the first control device 121 (S401), it periodically determines whether the cause of the transmission outage has been resolved (S402). For example, the base station 111 may continuously retransmit a signal to check the operation status of the first control device 121 even during the transmission outage. Then, when the cause of the transmission outage is resolved (YES in S402), the base station 111 transmits a message to the first control device 121 inquiring whether it is OK to transmit radio waves using the shared frequency band (S403). For example, when the base station 111 determines that the cause of the transmission outage has been resolved by receiving a response to the signal to check the operation status of the first control device 121, it may subsequently transmit a message to the first control device 121 inquiring whether it is OK to transmit radio waves using the shared frequency band. The subsequent operation of the base station 111 is the same as that of FIG. 4, and therefore description thereof will be omitted.

[0038] 9 shows an example of a sequence between the base station 111 and the first control device 121 in this example. First, when the base station 111 starts communication using a shared frequency band, it transmits a signal to the first control device 121 to confirm the operation status and starts a predetermined timer (S901). When the base station 111 receives a response from the first control device 121 before the expiration of the predetermined timer (S902), it stops the predetermined timer. At the next timing corresponding to the alive monitoring period of the first control device 121, the base station 111 again transmits a signal to the first control device 121 to confirm the operation status and starts the predetermined timer (S903). When the base station 111 receives a response from the first control device 121 before the expiration of the predetermined timer (S904), it stops the timer. Then, at the next timing corresponding to the alive monitoring cycle of the first control device 121, the base station 111 transmits a signal to the first control device 121 to check the operating status and starts a predetermined timer (S905). If the predetermined timer expires without receiving a response to the signal, the base station 111 stops transmitting (S906). The base station 111 then periodically transmits a signal to the first control device 121 to check the operating status (S907 to S909). If the base station 111 receives a response from the first control device 121 (S910), the base station 111 stops the predetermined timer and transmits a message to the first control device 121 inquiring whether or not it is permitted to transmit radio waves using the shared frequency band (S911). If the base station 111 receives a response from the first control device 121 (S912), the base station 111 releases or maintains the transmission suspension based on the response (S913).

[0039] The first timer used by the base station 111 when checking the operation status of the first control device 121 and the second timer used by the base station 111 when checking whether or not it is permitted to transmit radio waves using the shared frequency band to the first control device 121 may be the same or different. In this example, the third timer used by the base station 111 when checking the operation status of the first control device 121 before shutting down the radio waves may be the same or different. The fourth timer used by the base station 111 when checking the operation status of the first control device after shutting down the radio waves may be the same or different. For example, the base station 111 may set the expiration date of the third timer to be shorter than the expiration date of the fourth timer. This allows the base station 111 to quickly detect that it should shut down the radio waves before shutting down the radio waves, and after shutting down the radio waves, may reduce the processing load on the network and the base station itself, which would be caused by frequently checking the first control device 121. The base station 111 may set the expiration date of the third timer to be longer than the expiration date of the fourth timer. This allows the base station 111 to quickly detect that communication between itself and the first control device 121 has been restored after an outage, and can shorten the interruption of wireless communication services to the user terminal.

[0040] As described above, in this example, when communicating using the shared frequency band, the base station 111 monitors the first control device 121 to determine whether it is alive or dead, and if it does not receive a response from the first control device 121, it suspends transmission. This allows the base station 111 to communicate using the shared frequency even in a situation where communication between the base station 111 and the first control device 121 is not possible, thereby preventing interference with the primary user's wireless system. Furthermore, when communication with the first control device 121 is restored, the base station 111 checks whether it is permitted to transmit radio waves using the shared frequency band, and releases or maintains the suspension of transmission based on the response. This allows the base station 111 to maintain the suspended transmission state even if it receives a suspension instruction from the frequency sharing management device 131 during a period when it was unable to communicate with the first control device 121. Furthermore, the base station 111 continues to check the operating status of the first control device 121 in a situation where communication between the base station 111 and the first control device 121 is not possible. This allows the base station 111 to quickly resume the suspension of radio access services to the user terminal when communication between the base station 111 and the first control device 121 is restored.

[0041] As described above, according to this embodiment, after the cause of the outage is resolved, the base station 111 checks whether the first control device 121 has not notified it of suspension information indicating that transmission of radio waves using the shared frequency band should be suspended, and releases or maintains the outage depending on the result. This configuration makes it possible to avoid a situation in which interference occurs when the base station 111 uses a shared frequency band when the shared frequency band is being used by a primary user. This enables the wireless communication system 100 to provide wireless communication services using a shared frequency band other than the frequency band allocated to the mobile communication system. This makes it possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0042] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the invention. [Explanation of symbols]

[0043] 111: base station, 121: first control device, 122: second control device, 131: frequency sharing management device

Claims

1. A base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, a receiving means for receiving information indicating whether or not transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; a control means for controlling the suspension and release of transmission of radio waves using the frequency band based on reception of the information or a predetermined factor other than reception of the information; and a confirmation means for confirming that, after the suspension based on the other predetermined cause, suspension information indicating that transmission of radio waves using the frequency band should be suspended has not been notified from the control device before the suspension is released based on the resolution of the other predetermined cause, The control means controls to release the stop when it is confirmed that the stop information has not been notified, and to maintain the stop when it is not confirmed that the stop information has not been notified. A base station device characterized by:

2. The confirmation means, before canceling the suspension, transmits a message to the control device inquiring whether or not it is permitted to transmit radio waves using the frequency band, and performs the confirmation by receiving a response to the message from the control device.

2. The base station apparatus according to claim 1, wherein:

3. When the control means receives the stop information from the control device in response to the confirmation, the control means maintains the stop until it receives a permission notice from the control device indicating that it is permitted to transmit radio waves using the frequency band.

3. The base station device according to claim 2, wherein:

4. If a response is not received from the control device within a predetermined period of time after the message is sent by the confirmation means to the control means, The control means controls to maintain the stop, The confirmation means resends the message.

4. The base station apparatus according to claim 2, wherein the base station apparatus is a base station.

5. If the control means is notified of the stop information from the control device and has not received a permission notice from the control device indicating that radio waves using the frequency band may be transmitted after the stop information is notified during the period from when the stop is initiated based on the other predetermined factor until the other predetermined factor is resolved, the control means maintains the stop until the permission notice is received, and releases the stop based on the reception of the permission notice.

2. The base station apparatus according to claim 1, wherein:

6. The confirmation means performs the confirmation by monitoring the operating state of the control device.

2. The base station apparatus according to claim 1, wherein:

7. The control means releases the suspension based on the determination by the monitoring that the control device has been operating normally over a period from when the suspension was initiated based on the other predetermined factor until the other predetermined factor is resolved.

7. The base station apparatus according to claim 6,

8. The control means controls the control device to maintain the stop if it is not confirmed that the control device has been operating normally during the period.

8. The base station device according to claim 7,

9. The confirmation means performs the monitoring even when the stop is not being performed, When the control means has not performed the stop, if it is not confirmed that the control device is operating normally during the monitoring, the control means controls the device to perform the stop.

7. The base station apparatus according to claim 6,

10. A base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, a receiving means for receiving information indicating whether or not transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; a control means for controlling the suspension and release of transmission of radio waves using the frequency band based on reception of the information or a predetermined factor other than reception of the information; a confirmation means for confirming that the device is in a state where it can receive stop information from the control device, the stop information indicating that transmission of radio waves using the frequency band should be stopped; When it is not possible to confirm that the stop information can be received, the control means controls the device to stop even if the other predetermined factors have not occurred. A base station device characterized by:

11. A control method executed by a base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, comprising: a receiving step of receiving information indicating whether or not transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; a control step of controlling the suspension and cancellation of transmission of radio waves using the frequency band based on reception of the information or a predetermined factor other than reception of the information; a confirmation step of confirming that, after the suspension based on the other predetermined factor, suspension information indicating that transmission of radio waves using the frequency band should be suspended has not been notified from the control device before the suspension is released based on the resolution of the other predetermined factor, The control step performs control to cancel the stop when it is confirmed that the stop information has not been notified, and to maintain the stop when it is not confirmed that the stop information has not been notified. A control method comprising:

12. A control method executed by a base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, comprising: a receiving step of receiving information indicating whether or not transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; a control step of controlling the suspension and cancellation of transmission of radio waves using the frequency band based on reception of the information or a predetermined factor other than reception of the information; a confirmation step of confirming that the device is in a state where it can receive stop information from the control device, the stop information indicating that transmission of radio waves using the frequency band should be stopped; In the control step, when it is not possible to confirm that the stop information can be received, the control is performed so as to stop the vehicle even if the other predetermined factors have not occurred. A control method comprising:

13. A computer included in a base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, receiving information indicating whether or not transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; based on reception of the information or a predetermined factor other than reception of the information, control is performed to stop transmission of radio waves using the frequency band and to release the stop; after the suspension is performed based on the other predetermined factor, and before the suspension is released based on the resolution of the other predetermined factor, a confirmation is made that suspension information indicating that transmission of radio waves using the frequency band should be suspended has not been notified from the control device; When it is confirmed that the stop information has not been notified, the stop is cancelled, and when it is not confirmed that the stop information has not been notified, the stop is maintained. Program for.

14. A computer included in a base station device in a wireless communication system capable of performing wireless communication by sharing a frequency band used by another wireless system, receiving information indicating whether or not transmission of radio waves using the frequency band should be stopped from a control device included in the wireless communication system; based on reception of the information or a predetermined factor other than reception of the information, control is performed to stop transmission of radio waves using the frequency band and to release the stop; A program for confirming that a state in which stop information indicating that transmission of radio waves using the frequency band should be stopped can be received from the control device, If it is not possible to confirm that the stop information can be received, control is performed to stop the device even if the other predetermined factors have not occurred. program.

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