Control device, base station, control method, and program

Abstract

To perform flexible operation of networks while preventing the interference between the networks.SOLUTION: When a first pattern is used in a first network in which time slots of time division duplex (TDD) are allocated to an uplink and a downlink being the directions of communication between a base station and a terminal, and the first pattern and a second pattern different from the first pattern in allocation of the directions of communication to the time slots can be used in a second network for communication with the TDD between the base station and the terminal, based on satisfaction of a predetermined condition, a control unit controls base stations belonging to the second network to use the time slots in which the directions of communication allocated in the first pattern and the second pattern match each other and not to use the time slots in which the allocated directions of communication do not match each other.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a technique for suppressing interference between wireless communication networks. [Background technology]

[0002] The fifth generation (5G) cellular communication standard, standardized by the 3rd Generation Partnership Project (3GPP), has been put into practical use. In addition to networks deployed nationwide by telecommunications carriers, 5G allows the use of local 5G, which allows networks to be deployed by regions and companies other than telecommunications carriers. Regional BWA (Broadband Wireless Access) is also known as a network that can be deployed by regions and companies other than telecommunications carriers. In the following, networks deployed nationwide by telecommunications carriers are sometimes referred to as carrier networks, and local 5G and regional BWA networks are sometimes referred to as local networks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2020 / 0008087 Summary of the Invention [Problem to be solved by the invention]

[0004] In an environment where different networks, such as a carrier network and a local network, coexist, it is necessary to suppress interference caused by communication of a network, such as a local network, which has a relatively low priority, with respect to communication of a network, such as a carrier network, which should be prioritized. For example, when a carrier network communicates by time division duplex (TDD), if the local network performs downlink communication in a time slot in which uplink communication is performed in the carrier network, a signal from a base station of the local network may cause interference in the base station of the carrier network. In response to this, the local network can suppress the occurrence of interference by synchronizing the time slots in which uplink communication and downlink communication are performed with the carrier network. However, it is assumed that the local network will perform flexible operation without synchronizing the transmission timing of uplink and downlink with that of the carrier network, for example, by increasing the number of uplink slots when the communication demand in the uplink is high in the local network. In order to perform such flexible operation, a technology for suppressing the influence of interference between networks is important (see Patent Document 1).

[0005] The present invention provides a technique that enables flexible network operation while suppressing interference between networks. [Means for solving the problem]

[0006] A control method according to one aspect of the present invention is a method for controlling a time slot allocation pattern for a first network, in which time slots of time division duplexing (TDD) are allocated to uplink and downlink, which are directions of communication between a base station and a terminal, and a second network different from the first network is capable of using the first pattern and a second pattern in which the allocation of the directions of communication to time slots is different from the first pattern, for TDD communication between a base station and a terminal, by controlling a time slot belonging to the second network to use the time slots in which the directions of communication assigned in the first pattern and the second pattern match, and not to use the time slots in which the directions of communication assigned in the first pattern and the second pattern do not match, based on a predetermined condition being satisfied.1. Control the base station The predetermined condition includes that the first base station operates using the first pattern, and a second base station of the second network, which is in a mutually interfering relationship with the first base station, operates using the second pattern. . Effect of the Invention

[0007] According to the present invention, it is possible to operate networks flexibly while suppressing interference between networks. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an example of a system configuration. [Diagram 2] FIG. 1 is a diagram illustrating an example of the configuration of TDD time slots available in a local network. [Diagram 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station device. [Figure 4] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. [Diagram 5] FIG. 11 is a diagram showing an example of a flow of processing executed by a base station of a local network. [Figure 6] FIG. 11 is a diagram showing an example of a process flow executed by a node in a core network of a local network. [Figure 7] A figure showing an example of base station information used by nodes in a core network of a local network. [Figure 8] FIG. 11 is a diagram showing an example of a process flow executed by a node in a core network of a local network. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] (System Configuration) FIG. 1 shows an example of the configuration of a system according to this embodiment. The system according to this embodiment includes a plurality of networks. Here, all of the plurality of networks are cellular communication networks conforming to the cellular communication standard of the Third Generation Partnership Project (3GPP). The first network is a carrier network 101 provided nationwide by a wireless communication carrier, and the second network is a local network 103 provided locally by a region, a company, or the like. Note that these are only examples, and the following discussion can be applied to any system in which a plurality of TDD systems whose frame timings are synchronized coexist. In one example, the local network 103 is configured within an area in which the carrier network 101 is deployed. That is, the local network 103 is deployed in an overlapping area within the area in which the carrier network 101 is deployed. Note that these are only examples, and the following discussion can be applied to other types of wireless communication networks. Note that in this embodiment, the carrier network 101 and the local network 103 are operated using adjacent frequency bands. 1 shows an example in which carrier network 101 uses the 4.5 GHz band, and local network 103 uses the 4.6 GHz band and 4.7 GHz band. In this embodiment, base station 104 and base station 105 of local network 103 use the 4.6 GHz band, and base station 106 uses the 4.7 GHz band adjacent to the 4.6 GHz band.

[0011] In the carrier network 101, in an area where wireless communication with a base station 102 for providing the communication service of the carrier network 101 is possible, a wireless communication service is provided to a terminal 108 of a user who has a contract with a wireless communication carrier. The base station 102 of the carrier network 101 is connected to a core network (not shown), and mobility management, session management, and the like are performed by a node in the core network. Similarly, in the local network 103, in an area where wireless communication with any of the base stations 104 to 106 of the local network 103 is possible, a wireless communication service is provided to a terminal 109 prepared for communication of the local network. Here, in this embodiment, the carrier network 101 is a network that should be prioritized, and the local network 103 communicates after processing so that there is no interference with the communication of the carrier network 101 or the interference level is sufficiently small. Note that mobility management and session management of the local network 103 are performed by a node 107 in a core network independent of the core network of the carrier network 101.

[0012] It is considered that the carrier network 101 and the local network 103 communicate with each other at their own timing. In this case, even if the carrier network 101 and the local network 103 communicate with each other using, for example, orthogonal frequency division multiplexing (OFDM) that can ensure mutual orthogonality, the orthogonality is not guaranteed because the timing of the radio frames does not match, and mutual interference may occur. This interference can be suppressed, for example, by base stations 104 to 106 transmitting and receiving radio frames in synchronization with base station 102 of the carrier network 101 to match the timing of the radio frames.

[0013] There are multiple patterns of situations in which mutual interference occurs. For example, interference from the carrier network 101 to the local network 103 may be (1) interference from the base station 102 to the base stations 104 to 106, and (2) interference from the base station 102 to the terminal 109. Furthermore, interference from the carrier network 101 to the local network 103 may be (3) interference from the terminal 108 to the base stations 104 to 106, and (4) interference from the terminal 108 to the terminal 109. Furthermore, interference from the local network 103 to the carrier network 101 may be (5) interference from the base stations 104 to 106 to the base station 102, and (6) interference from the base stations 104 to 106 to the terminal 108. Furthermore, interference from the local network 103 to the carrier network 101 may be (7) interference from the terminal 109 to the base station 102, and (8) interference from the terminal 109 to the terminal 108. In this case, by assuming that the local network 103 is subordinate to the carrier network 101, the interference of (1) to (4) is tolerated to a certain extent, and the local network 103 can perform processing to reduce the effects of this interference. On the other hand, the interference of (5) to (8) is interference with a prioritized network, so the local network 103 must prevent such interference from occurring or sufficiently suppress such interference.

[0014] In one example, the interference of (5) can be sufficiently suppressed by having base stations 104 to 106 of local network 103 transmit signals at the same timing as base station 102 of carrier network 101 transmits a signal. Also, by making the frequency band of the signal transmitted and received by base station 102 of carrier network 101 different from the frequency band of the signal transmitted and received by base stations 104 to 106 of local network 103, the interference of (6) and (7) can be sufficiently suppressed. Also, the interference of (8) can be sufficiently suppressed by having terminal 109 of local network 103 transmit a signal at the same timing as terminal 108 of carrier network 101 transmits a signal.

[0015] Meanwhile, in recent cellular communication standards, a time division duplex (TDD) system has been standardized, which allows flexible change of the ratio between the downlink, in which a signal is transmitted from a base station to a terminal, and the uplink, in which a signal is transmitted from a terminal to a base station. The TDD system is a system for performing uplink and downlink communications using a common frequency band, and each of a plurality of time slots separated by unit time is assigned to either the uplink or the downlink. Since there is generally a high demand for downlink communications, the carrier network 101 tends to assign many time slots to the downlink. On the other hand, it may be assumed that the local network 103 requires more uplink time slots than the carrier network 101 depending on its application. In this case, the local network 103 can assign time slots to the uplink and downlink independently of the carrier network 101's assignment of time slots to the uplink and downlink (see Patent Document 1). However, in this case, the interferences (5) and (8) described above occur.

[0016] On the other hand, in the local network 103, it is possible to change and use only a part of the time slots allocated in the carrier network 101. In one example, it is possible to set that only a part of the slots allocated to the uplink in the carrier network 101 is allocated to the downlink, and the slots allocated to the downlink in the carrier network 101 are used for the downlink as they are. It is also possible to set that only a part of the slots allocated to the downlink in the carrier network 101 is allocated to the uplink, and the slots allocated to the uplink in the carrier network 101 are used for the uplink as they are. According to the former setting, the terminal 109 does not transmit a signal while the downlink communication is being performed in the carrier network 101, so that the interference of (8) can be suppressed. On the other hand, according to the latter setting, the base stations 104 to 106 do not transmit signals while the uplink communication is being performed in the carrier network 101, so that the interference of (5) can be suppressed.

[0017] Here, from the viewpoint of protecting the base station 102 of the carrier network 101, a case where a setting that does not cause interference (5) is used will be considered. An example of the setting of time slots available in the local network 103 in this case is shown in FIG. 2. Here, a time slot allocation pattern in which the settings of the uplink and downlink time slots of the carrier network 101 match those of the carrier network 101 is called a synchronous TDD pattern. On the other hand, a time slot allocation pattern in which the direction of some communication (uplink or downlink) of the time slot allocation of the carrier network 101 is changed is called quasi-synchronous TDD communication. In this embodiment, in particular, as shown in FIG. 2, a TDD pattern in which the time slots allocated to the downlink in the time slots of the carrier network 101 are used as the uplink is referred to as quasi-synchronous TDD, referring to communication used in the local network 103. In FIG. 2, a time slot allocated to the uplink communication is indicated by "U", a time slot allocated to the downlink communication is indicated by "D", and a time slot indicating a period of switching from the downlink to the uplink is indicated by "S".

[0018] In this embodiment, in carrier network 101, communication is performed according to the synchronous TDD pattern of Fig. 2. However, Fig. 2 is only an example, and the use of any one of a plurality of TDD settings may be permitted in carrier network 101. Meanwhile, in local network 103, a synchronous TDD pattern, which is the same TDD pattern as carrier network 101, and an asynchronous TDD pattern in which the time slots of carrier network 101 assigned to the downlink are used as the uplink.

[0019] In this embodiment, the base stations 104 to 106 of the local network are normally operated in a quasi-synchronous TDD pattern for low latency communication and high speed uplink communication. On the other hand, when the base stations 104 to 106 of the local network cause interference to the carrier network 101, the operation can be switched from an asynchronous TDD pattern to a synchronous TDD pattern. For example, when a terminal 109 connected to the base station 104 operated in a quasi-synchronous TDD pattern causes interference to a terminal 108 of the carrier network, the base station 104 is changed to operate in a synchronous TDD pattern.

[0020] In this case, in the local network 103, the base station 104 operates in a synchronous TDD pattern, and the base stations 105 and 106 operate in a quasi-synchronous TDD pattern. As a result, downlink communication of the base station 104 and uplink communication of the base stations 105 and 106 may interfere with each other within the local network 103. As a result, for example, the effective throughput and delay time of the uplink communication of the base station 105 and the base station 106 operating in the quasi-synchronous TDD pattern may not be able to satisfy requirements.

[0021] In this embodiment, in consideration of such circumstances, the base stations 104 to 106 of the local network 103 are made to execute a technique for suppressing the influence of interference based on the TDD pattern used in each base station. Specifically, the base stations 104 to 106 use time slots in which the communication direction (uplink or downlink) matches between the first and second patterns of TDD based on a predetermined condition, and do not use time slots in which the communication direction does not match. For example, when the synchronous TDD pattern and the quasi-synchronous TDD pattern in FIG. 2 are used, the base stations 104 to 106 for which a predetermined condition is satisfied do not use time slots with time slot numbers 8, 9, 18, and 19, and perform communication in the remaining time slots. The predetermined condition may be, for example, operation in a synchronous TDD pattern. Also, the predetermined condition may be that the base stations 104 to 106 or a connected terminal are present in a position that may cause interference to the carrier network 101. In addition to the above conditions, the predetermined conditions may include the presence of other base stations in the vicinity that operate using quasi-synchronous TDD patterns on the same or adjacent frequencies.

[0022] Also, the base stations 104 to 106 may assume that there is another base station that does not use some of the time slots as described above, and may preferentially use the time slots not used by the other base station so that the efficiency of communication of the other base station does not deteriorate. Then, while operating in the quasi-synchronous TDD pattern, the base stations 104 to 106 identify the communication direction in the quasi-synchronous TDD pattern of the time slots not used by the other base station. Then, the base stations 104 to 106 restrict the use of the time slots used by the other base station among the time slots assigned to the communication direction. For example, according to the above-mentioned technique, the other base station does not use the time slots with time slot numbers 8, 9, 18, and 19, but the communication direction of the quasi-synchronous TDD pattern in these time slots is the uplink. Then, the base stations 104 to 106 restrict the use of the time slots with time slot numbers 4, 5, 14, and 15 that are assigned to the uplink in the quasi-synchronous TDD pattern and are used by the other base station. The restrictions include not using the frequency band and using the frequency band only when retransmitting data. This can reduce the probability that the second communication of the base stations 104 to 106 interferes with the first communication of another base station in the uplink.

[0023] The configuration of a device that performs such processing and an example of the flow of processing will be described below with reference to the drawings.

[0024] (Device configuration) 3 shows an example of the hardware configuration of base stations 104 to 106 of local network 103. Base stations 104 to 106 each have a control unit 301, a storage unit 302, a wireless communication unit 303, and an antenna control unit 304, for example, as their hardware configuration.

[0025] The control unit 301 includes one or more processors, such as a central processing unit (CPU) and a micro processing unit (MPU). The control unit 301 may include a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), and the like. The storage unit 302 stores various information, such as a control program executed by the control unit 301, control parameters, a TDD pattern to be used, and connection terminal information. The control unit 301 controls the entire device, for example, by executing a control program stored in the storage unit 302. In one example, various operations described below are realized by the control unit 301 executing a control program stored in the storage unit 302.

[0026] The wireless communication unit 303 includes a circuit for performing communication conforming to 3GPP cellular communication standards, such as 5th generation (5G) New Radio (NR) and Long Term Evolution (LTE) conforming to the 3GPP standard. The wireless communication unit 303 includes, for example, a baseband chip and an RF (Radio Frequency) chip. The antenna control unit 304 controls an antenna for wireless communication by the wireless communication unit 303. The antenna control unit 304 may be included in the wireless communication unit 303, or may exist separately from the wireless communication unit 303. The antenna controlled by the antenna control unit 304 may be an antenna that can be used, for example, an antenna that can operate in both frequency bands that can be used by the carrier network 101 and the local network 103. However, this is just one example, and the antenna may be, for example, an antenna that can operate only in the frequency band of the local network 103, or an antenna that can operate in other frequency bands.

[0027] FIG. 4 is a diagram showing an example of the functional configuration of the base station device according to the present embodiment. The base station device has, as an example of its functional configuration, a signal transmission unit 401, a signal reception unit 402, a data storage unit 403, a connection control unit 404, a TDD pattern determination unit 405, and a TDD time slot use suppression unit 406. These functional configurations can be realized, for example, by the control unit 301 executing a program stored in the storage unit 302. The signal transmission unit 401 and the signal reception unit 402 transmit and receive signals having a frame configuration defined in the 3GPP cellular communication standard. The data storage unit 403 stores software corresponding to the control to be executed, information related to cellular communication, and the like. The data storage unit 403 can store, for example, information on the operation mode (TDD pattern being used) currently used in the base station, as described later. The connection control unit 404 executes processing related to connection and disconnection of the terminal to the cellular network, such as communication of a radio resource control (RRC) message between the terminal and the base station. The connection control unit 404 can also execute processing related to connection with the core network function.

[0028] The TDD pattern determination unit 405 determines the TDD pattern to be used. For example, when a first terminal currently connected detects radio waves from a second terminal in the carrier network 101, the TDD pattern determination unit 405 determines that an uplink signal from the first terminal may interfere with the second terminal, and determines to use the synchronous TDD pattern. The TDD pattern determination unit 405 may also determine to use the synchronous TDD pattern when the TDD pattern determination unit 405 detects radio waves from the second terminal in its own device. Note that these are only examples, and the TDD pattern determination unit 405 may determine to use the synchronous TDD pattern when it determines that interference may occur with the second terminal when a quasi-synchronous TDD pattern is used. The TDD pattern determination unit 405 may also determine to use the synchronous TDD pattern when the frequency of communication in the uplink is low and the communication demand in the uplink can be satisfied even when the synchronous TDD pattern is used. When the synchronous TDD pattern is not used, the TDD pattern determination unit 405 determines to use the quasi-synchronous TDD pattern. That is, the TDD pattern determination unit 405 may determine to use a TDD pattern in which some of the time slots allocated to the downlink in the synchronous TDD pattern are allocated to the uplink. Note that the TDD pattern determination unit 405 may also determine to use a TDD pattern in which the uplink time slots in the synchronous TDD pattern are allocated to the downlink, on the condition that interference with the base station 102 of the carrier network 101 can be sufficiently suppressed. The TDD pattern determination unit 405 notifies the connection control unit 404 of the determined TDD pattern.

[0029] The TDD time slot usage suppression unit 406 executes processing related to suppressing the use of predetermined TDD time slots, which will be described later.

[0030] (Processing flow) Next, an example of the flow of a process for suppressing the use of a predetermined TDD time slot, which is executed by the TDD time slot usage suppression unit 406, will be described with reference to FIG. 5. This process is started in each of the base stations 104 to 106 of the local network 103 when each of these base stations is connected to the core network device 107 of the local network 103. This process can be realized by the control unit 301 of the base station of the local network 103 reading and executing a computer program stored in the storage unit 302. Note that this is just an example, and for example, dedicated hardware for executing the following process may be used in at least one of the base stations 104 to 106 of the local network 103. Note that, in the following, a case where the base station 104 executes the process will be described, but the base stations 105 and 106 can also execute similar processes.

[0031] After the process starts, the base station 104 acquires base station information on the base stations of the local network 103 present in the vicinity (S501). The base station 104 may acquire base station information on the base stations of the local network 103 present in the vicinity, for example, by using an inter-base station interface. The base station 104 may also acquire the base station information from, for example, a node in the core network. The base station present in the vicinity here may be, for example, another base station that provides the cell based on the cell included in the neighboring cell list defined by 3GPP. That is, the other base station that is determined to be adjacent in advance is determined to be the base station present in the vicinity. Also, for example, when the source of the radio wave detected by the terminal 109 connected to the base station 104 is another base station or a terminal connected to the other base station, the other base station may be treated as the base station present in the vicinity of the base station 104. When the adjacent base stations include base stations of other networks such as the base station of the carrier network 101, only the base stations belonging to the same local network 103 as the base station that executes this process may be extracted. In this embodiment, it is assumed that the base stations 104 to 106 are recognized as being present in the vicinity of each other. Therefore, the base station 104 acquires base station information regarding the base stations 105 and 106. Note that the base station information includes, for example, information indicating whether the base station is operated in a synchronous TDD pattern or a quasi-synchronous TDD pattern. The base station information may also include information regarding the frequency band being used by the base station that provides the base station information.

[0032] Next, the base station 104 determines whether or not the base station itself is currently operating in a synchronous TDD pattern (S502). If the base station 104 is operating in a synchronous TDD pattern (YES in S502), the base station 104 determines whether or not there is a base station operating in a quasi-synchronous TDD pattern in the same frequency band as the base station itself or in an adjacent frequency band based on the acquired base station information (S503). If the base station 104 determines that there is no such base station in the vicinity (NO in S503), the base station 104 ends the process without imposing any particular restriction such as a restriction on the use of some time slots. On the other hand, if the base station 104 determines that there is such a base station in the vicinity (YES in S503), the base station 104 does not use time slots whose link directions do not match between the synchronous TDD pattern and the quasi-synchronous TDD pattern (S504).

[0033] For example, around the base station 104, the base station 105 operates in a quasi-synchronous TDD pattern in the same frequency band as the base station 104, and the base station 106 operates in a quasi-synchronous TDD pattern in a frequency band adjacent to the frequency band used by the base station 104. Therefore, the base station 104 does not use a time slot in which the uplink and downlink directions do not match between the quasi-synchronous TDD pattern and the synchronous TDD pattern used by these base stations 105 and 106. For example, when the base station 105 and the base station 106 use the quasi-synchronous TDD pattern shown in FIG. 2, the base station 104 does not use time slots with time slot numbers 8, 9, 18, and 19. In other words, the base station 104 operates according to a new TDD pattern in which the time slots in which the communication directions match between the synchronous TDD pattern and the quasi-synchronous pattern are left blank for the time slots in which the communication directions do not match. This makes it possible to prevent communication of base station 104 from interfering with communication of carrier network 101 using a synchronous TDD pattern, and also to prevent communication of base stations 105 and 106 of local network 103 using an asynchronous TDD pattern. This makes it possible to suppress the probability of errors occurring in uplink communication of base stations 105 and 106, for example, and reduce communication delays.

[0034] The above processing is performed by the base station 104 operating using a synchronous TDD pattern. If such a base station 104 exists, the surrounding base stations 105 and 106 operating using quasi-synchronous TDD patterns may perform processing based on the above processing of the base station 104.

[0035] For example, when the base station 105 determines that its own device is operating in an asynchronous TDD pattern (NO in S502), it determines whether there is a base station operating in a synchronous TDD pattern in the same frequency band as its own device (S505). The base station 105 has acquired the base station information of the base station 104 in S501, and determines that the base station 104 is operating in a synchronous TDD pattern at the same frequency as its own device (YES in S505). In this case, the base station 105 can operate so as to suppress the use of uplink time slots in common between the synchronous TDD pattern and the asynchronous TDD pattern. That is, the base station 105 suppresses the use of time slots numbered 4, 5, 14, and 15. This is a process for ensuring that the base station 104 can surely execute uplink communication because the base station 104 stops using the time slots numbered 8, 9, 18, and 19. That is, if the base station 105 uses the time slots numbered 4, 5, 14, and 15, it may interfere with the uplink communication in the base station 104, so the use of some time slots is restricted to suppress this interference. For example, the base station 105 may be configured such that only retransmitted data is transmitted in the time slots numbered 4, 5, 14, and 15 (S506). That is, in the base station 105, if communication is successful in the time slots numbered 8, 9, 18, and 19, the time slots numbered 4, 5, 14, and 15 are not used. Also, the base station 105 may be configured not to use the time slots numbered 4, 5, 14, and 15 even in retransmission. Thereby, the success rate of the uplink communication of the base station 104 communicating in the synchronous TDD pattern can be improved.

[0036] On the other hand, the base station 106 determines that the base station itself is operating in an asynchronous TDD pattern (NO in S502), but determines that there is no surrounding base station operating in a synchronous TDD pattern in the same frequency band as the base station itself (NO in S505). This is because the frequency band used by the base station 106 is different from the frequency band used by the base station 104. In this case, even if the base station 106 uses the time slots with time slot numbers 4, 5, 14, and 15, it is expected that interference with the communication of the base station 104 will be limited. For this reason, the base station 106 ends the process without placing any particular restrictions on the time slots to be used. Note that the base station 106 may also not use the time slots with time slot numbers 4, 5, 14, and 15, or may only retransmit data in these time slots.

[0037] In this processing example, the processing of S504 and S506 is executed to reduce errors in uplink time slots in the local network 103, but only one of these processing may be executed. Also, the base station 104 operating in a synchronous TDD pattern may execute the processing of S504 without executing the determination processing of S503.

[0038] As described above, each base station in local network 103 autonomously restricts the use of some of the time slots, thereby making it possible to suppress the occurrence of interference within local network 103 while preventing interference with carrier network 101. Furthermore, by partially restricting uplink communication in a quasi-synchronous TDD pattern within local network 103, it is possible to suppress interference with base stations operating in a synchronous TDD pattern and improve the efficiency of uplink communication.

[0039] <Modification> In the above-mentioned processing example, each base station in the local network 103 executes the processing, but the present invention is not limited to this. In this modified example, a case will be described in which the node 107 on the core network to which each base station of the local network 103 is connected executes processing to control the base station, such as setting a time slot in which communication should be suppressed. The configuration of the node 107 is generally similar to the configuration of the base station (the configuration of FIG. 3 and FIG. 4). However, since the node 107 is generally connected to each base station using a wired line, the wireless communication unit 303 can be replaced with a communication unit that performs wired communication, and the antenna control unit 304 and the antenna can be replaced with, for example, an interface for wired communication. In addition, the signal transmission unit 401 and the signal reception unit 402, and the connection control unit 404 of the node 107 are configured to perform communication within the core network according to, for example, the 5G core (5GC) standard, manage connection / disconnection with each base station, and communicate with each base station. In addition, the TDD pattern determination unit 405 and the TDD time slot usage suppression unit 407 perform overall processing for each base station to be controlled by the node 107. Using this configuration, the node 107 executes the above-mentioned processing for a plurality of base stations in the local network 103 in an integrated manner.

[0040] An example of the flow of processing executed in the node 107 will be described with reference to FIG. 6. This processing is executed in response to the connection of base stations such as the base stations 104 to 106 to the local network 103. The node 107 recognizes, for example, that the base station device has been connected to the local network 103 and that various settings as a base station of the local network 103 have been completed by monitoring a predetermined node, and starts the processing of FIG. 6. In addition, a base station may connect to the node 107 to start the processing. Note that this processing can be realized by the control unit 302 of the node 107 reading and executing a computer program stored in the storage unit 303.

[0041] Node 107 can obtain base station information regarding each base station when connecting to the base station, that is, before the start of the process in FIG. 6. The base station information here may include, for example, base station identification information (base station ID) and adjacent base station information existing around (base station ID of the base station providing adjacent cells). Further, the base station information may include used frequency band information. Note that when Node 107 determines the frequency band to be used in each base station, the base station information may not include this information. Furthermore, when the base station determines the TDD pattern, the information indicating whether each base station operates according to the synchronous TDD pattern or the quasi-synchronous TDD pattern may be included. Note that when Node 107 determines whether each base station uses the synchronous TDD pattern or the quasi-synchronous TDD pattern, the base station information may not include this information. FIG. 7 shows an example of the base station information obtained by Node 107 in this embodiment. In the example of FIG. 7, it is assumed that the base station ID of base station 104 is 104, the base station ID of base station 105 is 105, and the base station ID of base station 106 is 106. As shown in FIG. 7, this base station information indicates that base stations 104 to 106 exist around each other, and that only base station 104 is operated according to the synchronous TDD pattern.

[0042] In the process of FIG. 6, Node 107 first determines the base station with the smallest base station ID value as the first base station to be processed (S601). In this processing example, the base stations to be processed are selected in ascending order of the base station ID value, but this is just an example, and other orders may be used. For example, the base stations to be processed may be selected in descending order of the base station ID value. Also, a serial number may be assigned to the base stations to be processed according to an arbitrary rule, and the process may be executed in the order of the serial numbers. For example, the serial number may be assigned in an arbitrary order such as ascending / descending order of the IP address assigned to the base station, the order in which the base stations are installed, or ascending / descending order of the capabilities of the base stations.

[0043] Next, node 107 executes the TDD time slot usage suppression process (S602), which will be described later, for the first base station to be processed selected in S601. Then, node 107 judges whether execution of the process of S602 has been completed for all base stations to be processed (S603), and if not completed (NO in S603), selects the next base station to be processed (S604) and executes the process of S602. On the other hand, if node 107 judges that execution of the process of S602 has been completed for all base stations to be processed (YES in S603), it ends the process.

[0044] The process executed in S602 is performed, for example, as shown in FIG. 5. That is, the node 107 first acquires information on the base stations of the local network 103 existing around the base station to be processed (S501). Then, when the base station to be processed is operating in a synchronous TDD pattern (YES in S502), the node 107 judges whether there is a surrounding base station operating in a quasi-synchronous TDD pattern in the same frequency band as the base station to be processed or in an adjacent frequency band (S503). When such a surrounding base station exists (YES in S503), the node 107 decides not to allow the base station to be processed to use a time slot in which the uplink and downlink directions are different between the synchronous TDD pattern and the quasi-synchronous TDD pattern (S504). On the other hand, when such a surrounding base station does not exist (NO in S503), the node 107 ends the process without setting a time slot to be restricted from use for the base station to be processed. Furthermore, when the base station to be processed is operating in a quasi-synchronous TDD pattern (NO in S502), node 107 determines whether there is a surrounding base station operating in a synchronous TDD pattern in the same frequency band as the base station to be processed (S505). If such a surrounding base station is present (YES in S505), node 107 restricts the use by the base station to be processed of time slots in which the uplink and downlink directions match in the synchronous TDD pattern and the asynchronous TDD pattern (S506). On the other hand, when there is no such surrounding base station (NO in S505), node 107 does not set any time slots to be restricted for use by the base station to be processed, and ends the process.

[0045] In the processing example of FIG. 6, the node 107 first selects the base station 104 as the base station to be processed. The base station 104 operates in a synchronous TDD pattern, and the base stations 105 and 106 are located around the base station 104, which operate in the same or adjacent frequency bands using a quasi-synchronous TDD pattern. Therefore, the node 107 decides not to allow the base station 104 to use the time slots with the time slot numbers 8, 9, 18, and 19. Next, the node 107 selects the base station 105 as the base station to be processed. The base station 105 operates in a quasi-synchronous TDD pattern, and the base station 104 is located around the base station 105, which operates in the same frequency band using a synchronous TDD pattern. Therefore, the node 107 restricts the use of uplink time slots common to the synchronous TDD pattern and the quasi-synchronous TDD pattern, for example, by allowing the base station 105 to use the time slots with the time slot numbers 4, 5, 14, and 15 only for retransmission. Finally, node 107 selects base station 106 as the target base station. Base station 106 operates in a quasi-synchronous TDD pattern, and there is no base station operating in the same frequency band using a synchronous TDD pattern around base station 106. Therefore, node 107 does not impose any particular restriction on base station 106.

[0046] In this processing example, the processing of S504 and S506 is executed to reduce errors in uplink time slots in the local network 103, but only one of these processing may be executed. Also, the base station 104 operating in a synchronous TDD pattern may execute the processing of S504 without executing the determination processing of S503.

[0047] In this manner, node 107 can restrict the use of some of the time slots by each base station in local network 103, thereby preventing interference with carrier network 101 and suppressing the occurrence of interference within local network 103. Furthermore, by partially restricting uplink communication in a quasi-synchronous TDD pattern within local network 103, it is possible to suppress interference with base stations operating in a synchronous TDD pattern and improve the efficiency of uplink communication.

[0048] In the above process, the processing flow is described in which the base stations to be processed are selected one by one, and whether or not to restrict the use of the time slot for the base station and the content of the usage restriction are determined for the base station. However, the processing is not limited to this. For example, processing may be performed collectively for multiple base stations that exist in the vicinity of each other. The processing flow in this case is shown in FIG. 8.

[0049] The processes from S801 to S804 are the same as those from S501 to S504. That is, based on the information of the base station to be processed, if the base station is operating in a synchronous TDD pattern and there is a base station operating in the same or adjacent frequency band using an asynchronous TDD pattern around the base station, the node 107 restricts the communication of the base station to be processed. At this time, the node 107 also performs the restriction process collectively on the base stations operating in the quasi-synchronous TDD pattern around the base station to be processed. That is, the node 107 identifies the base stations operating in the quasi-synchronous TDD pattern around the base station to be processed and operating in the same frequency band (S805). Then, if such a base station exists (YES in S805), the node 107 restricts the use of the uplink time slot common to the synchronous TDD pattern and the quasi-synchronous TDD pattern for that base station in the same manner as in S506 (S806).

[0050] For example, while performing processing related to the base station 104, the node 107 determines the use restriction of the time slot in the base station 104 in S801 to S804, and determines the use restriction of the time slot in the base station 105 in S806. Note that the node 107 does not impose the use restriction of the time slot in S806 for the base station 106 in relation to the base station 104. After that, the node 107 does not perform the processing of FIG. 8 even if the processing has not yet been performed for the node 105. That is, the base station that became the processing target of S806 is excluded from the base stations to be processed. Also, the node 105 is excluded from the processing target of S806 in the processing related to the other base stations. This makes it possible to reduce the number of base stations to be processed, and therefore the processing load. On the other hand, the base station 106 is left as a base station to be processed because the use restriction of the time slot was not imposed in relation to the base station 104, but the use restriction of the time slot may be imposed in relation to the other base stations. This allows the processing to be performed without omission for all the base stations to be processed.

[0051] If the base station to be processed is operating in a quasi-synchronous TDD pattern (NO in S802), the node 107 judges whether there is another base station operating in a synchronous TDD pattern in the same or adjacent frequency band around the base station (S807, S808). If such another base station is present (YES in S807, YES in S808), the node 107 imposes a time slot usage restriction on this other base station similar to that in S504 (S809). If the frequency band used by this other base station is the same as that used by the base station to be processed (YES in S810), the node 107 imposes a time slot usage restriction on the base station to be processed similar to that in S506 (S811).

[0052] For example, when the node 107 selects the base station 105 as the base station to be processed first, the base station 104 operating in the same frequency band using a synchronous TDD pattern is present around the base station 105. Therefore, the node 107 imposes a time slot usage restriction by S809 on the base station 104, and further imposes a time slot usage restriction by S811 on the base station 105. Also, for example, when the node 107 selects the base station 106 as the base station to be processed first, the base station 104 operating in an adjacent frequency band using a synchronous TDD pattern is present around the base station 106. Therefore, the node 107 imposes a time slot usage restriction by S809 on the base station 104. In this case, since the frequency bands used by the base stations 104 and 106 are different, the process of S811 is not performed. After these processes, the node 107 does not perform the process of FIG. 8 for the node 104 even if the process has not yet been performed. That is, the base station that was the subject of the process of S809 is excluded from the base stations to be processed. In addition, node 104 is also excluded from the processing target of S809 in the processing related to other base stations. For example, if the processing of base station 105 is executed first and a time slot usage restriction is imposed on node 104 in S809, then when the processing of base station 106 is executed next, base station 104 is excluded from the processing target of S809. In this case, if base station 104 is the only other base station operating in a synchronous TDD pattern in S807, the processing of S808 may also be omitted. In this way, the processing load can be reduced.

[0053] In the above embodiment, the use of time slots with time slot numbers 4, 5, 14, and 15 is restricted for a base station operating in a quasi-synchronous TDD pattern when a base station operating in a synchronous TDD pattern using the same frequency band is present in the vicinity. However, this is only an example, and for example, the use of only some of the time slots with time slot numbers 4, 5, 14, and 15 may be restricted. Also, for example, a first base station operating in a quasi-synchronous TDD pattern and a second base station operating in a synchronous TDD pattern may be prioritized, and the above-mentioned restriction may be performed only when the second base station has a higher priority than the first base station. Also, multiple levels of priority may be assigned to each base station, and the number of time slots with time slot numbers 4, 5, 14, and 15 to be restricted in use may be determined according to the difference in priority. That is, when a value obtained by subtracting a second value indicating the priority of a base station operating in a quasi-synchronous TDD pattern from a first value indicating the priority of a base station operating in a synchronous TDD pattern is equal to or greater than a first predetermined value, the use of four time slots may be restricted. Also, when a value obtained by subtracting the second value from the first value is smaller than the first predetermined value and equal to or greater than a second predetermined value, the use of two of the above-mentioned four time slots may be restricted. Also, when a value obtained by subtracting the second value from the first value is smaller than the second predetermined value, the use of none of the above-mentioned four time slots may be restricted. In this manner, restrictions may be strengthened / relaxed in stages.

[0054] In addition, in the above embodiment, the restriction of the uplink communication has been described, but the present invention is not limited to this. For example, when a TDD pattern having more downlink time slots than the synchronous TDD pattern is used in the local network 103, the restriction of the downlink time slots may be performed in the same manner. That is, for a base station operating according to the synchronous TDD pattern in the local network 103, when there is a base station of another local network 103 operating according to a quasi-synchronous TDD pattern in the vicinity, the use of time slots with a communication direction that does not match may be restricted. That is, only time slots with the same uplink and downlink directions in the synchronous TDD pattern and the quasi-synchronous TDD pattern may be used, and time slots with a different direction may be left blank.

[0055] This makes it possible to suppress interference between the carrier network 101 and the local network 103, while allowing the local network 103 to be operated flexibly.

[0056] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0057] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0058] 101: carrier network, 102: base station of carrier network, 103: local network, 104-106: base stations of local network, 107: core network node of local network, 406: TDD time slot usage suppression unit

Claims

1. 1. A control method performed by one or more network devices, comprising: a first network using a first pattern in which time slots of time division duplex (TDD) are assigned to uplink and downlink, which are directions of communication between a base station and a terminal; and a second network different from the first network using the first pattern and a second pattern in which the assignment of the directions of communication to time slots is different from the first pattern for TDD communication between a base station and a terminal, the control method comprising: controlling a first base station belonging to the second network to use time slots in which the directions of communication assigned in the first pattern and the second pattern match, and not to use time slots in which the directions of communication assigned in the first pattern and the second pattern match, based on a predetermined condition being satisfied; the predetermined condition including a condition in which the first base station operates using the first pattern, and a condition in which a second base station of the second network, which is in a mutually interfering relationship with the first base station, operates using the second pattern.

2. the predetermined condition further includes that the second base station uses a second frequency band that is the same as or adjacent to a first frequency band used by the first base station; 2. The control method according to claim 1, further comprising: controlling the first base station to use a time slot of the first pattern, even if the first base station operates using the first pattern and the second base station, which is in a mutually interfering relationship with the first base station, operates using the second pattern, when the second base station is not using the second frequency band.

3. 3. The control method according to claim 1, further comprising the step of controlling the first base station to use, when the first base station operates using the first pattern and when the second base station is not present and is in a mutually interfering relationship with the first base station, even a time slot of the first pattern whose communication direction does not match that of the second pattern is controlled.

4. 4. The control method according to claim 1, wherein when the first base station is controlled not to use a first time slot in which the communication direction does not match between the first pattern and the second pattern, the second base station is controlled to restrict use of a third time slot in which the communication direction is the same as that of the first time slot, among second time slots in the second pattern that are different from the first time slot.

5. 5. The control method according to claim 4, further comprising controlling the second base station to use the third time slot for retransmission when the second base station should retransmit data transmitted in the first time slot, and controlling the second base station not to use the third time slot when the second base station does not retransmit data transmitted in the first time slot.

6. 6. The control method according to claim 4, further comprising controlling the second base station so as to restrict use of the third time slot when the second base station uses the same frequency band as the first base station, and controlling the second base station so as not to restrict use of the third time slot when the second base station uses a frequency band different from that of the first base station.

7. 7. The control method according to claim 1, wherein the second pattern is a pattern in which a part of the time slots allocated to the downlink in the first pattern is allocated to the uplink.

8. 8. The method of claim 1, wherein the first network is a nationwide cellular communications network and the second network is a locally provided cellular communications network.

9. A control method executed by a base station belonging to a second network different from a first network using a first pattern in which time division duplex (TDD) time slots are assigned to communication directions of an uplink and a downlink, the method comprising: When communicating with a terminal via TDD, a control method for controlling, when the first pattern and a second pattern in which the allocation of the communication direction to time slots is different from the first pattern, to use time slots in which the communication directions assigned in the first pattern and the second pattern match, and not to use time slots in which the communication directions assigned in the first pattern and the second pattern match, based on a predetermined condition being satisfied, the predetermined condition including a condition in which the base station operates using the first pattern and another base station of the second network that is in a mutually interfering relationship with the base station operates using the second pattern.

10. The predetermined condition further includes that the other base station uses a second frequency band that is the same as or adjacent to a first frequency band used by the base station; Even when the base station operates using the first pattern and another base station of the second network, which is in a mutually interfering relationship with the base station, operates using the second pattern, if the other base station is not using the second frequency band, control is performed so that even a time slot of the first pattern, the communication direction of which does not coincide with that of the second pattern, is used.

10. The control method according to claim 9.

11. 11. The control method according to claim 9, further comprising the step of: when the base station operates using the first pattern and there is no other base station operating using the second pattern that is in a mutually interfering relationship with the base station, performing control so as to use even time slots of the first pattern whose communication direction does not coincide with that of the second pattern.

12. A control method executed by a base station belonging to a second network different from a first network using a first pattern in which time division duplex (TDD) time slots are assigned to communication directions of an uplink and a downlink, the method comprising: When communicating with a terminal via TDD, a control method for restricting use of a third time slot, which has the same communication direction as the first time slot, among the second time slots in the second pattern, when the second network can use the first pattern and a second pattern in which the allocation of the communication direction to time slots is different from the first pattern, and when another base station in the second network does not use a first time slot, in which the communication direction does not match between the first pattern and the second pattern, but uses a second time slot, in which the assigned communication direction matches.

13. 13. The control method according to claim 12, wherein, when the base station is to retransmit data transmitted in the first time slot, the control is performed so that the third time slot is used for the retransmission, and, when the base station is not to retransmit the data transmitted in the first time slot, the control is performed so that the third time slot is not used.

14. 14. The control method according to claim 12, wherein the control is performed so as to restrict use of the third time slot when the base station uses the same frequency band as the other base stations, and the control is performed so as not to restrict use of the third time slot when the base station uses a frequency band different from that of the other base stations.

15. 15. The control method according to claim 9, wherein the second pattern is a pattern in which a part of the time slots allocated to the downlink in the first pattern is allocated to the uplink.

16. 16. A method according to any one of claims 9 to 15, wherein the first network is a nationwide provided cellular communication network and the second network is a locally provided cellular communication network.

17. A control device, a control means for controlling a first base station belonging to the second network to use a time slot in which the directions of communication assigned in the first pattern and the second pattern are the same and not to use a time slot in which the directions of communication assigned in the first pattern and the second pattern are not the same, when a first network uses a first pattern in which time slots of time division duplex (TDD) are assigned to uplink and downlink, which are directions of communication between a base station and a terminal, and a second network different from the first network is available for TDD communication between a base station and a terminal, based on a predetermined condition being satisfied; A control device characterized in that the specified conditions include the first base station operating using the first pattern and a second base station of the second network that is in a mutually interfering relationship with the first base station operating using the second pattern.

18. A base station that belongs to a second network different from a first network using a first pattern in which time division duplex (TDD) time slots are assigned to an uplink and a downlink that are communication directions, and that communicates with a terminal by TDD, comprising: a control means for controlling, when the first pattern and a second pattern in which the allocation of the communication direction to time slots is different from that of the first pattern, to use time slots in which the communication directions assigned in the first pattern and the second pattern match, and not to use time slots in which the communication directions assigned in the first pattern and the second pattern do not match, based on a predetermined condition being satisfied, in the second network; A base station characterized in that the specified conditions include the base station operating using the first pattern and another base station of the second network that is in a mutually interfering relationship with the base station operating using the second pattern.

19. A base station that belongs to a second network different from a first network using a first pattern in which time division duplex (TDD) time slots are assigned to an uplink and a downlink that are communication directions, and that communicates with a terminal by TDD, comprising: A base station characterized in that, in the second network, the first pattern and a second pattern in which the allocation of the communication direction to time slots is different from the first pattern can be used, and when another base station in the second network does not use a first time slot in which the communication direction does not match between the first pattern and the second pattern, but uses a second time slot in which the assigned communication direction matches, the base station has a control means for controlling to restrict use of a third time slot, of the second time slots in the second pattern, in which the communication direction is the same as that of the first time slot.

20. A program for causing a computer to function as the control means of the control device according to claim 17.

21. A program for causing a computer to function as the control means of the base station according to claim 18 or 19.

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