JP2021132269A - Detection of discontinuous service area in overlay cell configuration and wireless network design based on detection - Google Patents

Abstract

To prevent the exhaustion of wireless resources in a large-sized first cell even when the operating status of a wireless network in an overlay cell configuration changes.SOLUTION: A management device that manages the setting of a frequency priority parameter of a second cell in an overlay cell configuration in which a first cell and a plurality of second cells having a cell size smaller than that of the first cell coexist acquires a measurement report including the reception intensity of a mobile station located in the plurality of second cells from base stations of the plurality of second cells, detects a discontinuous boundary area in which the other second cells are not continuous in the outer peripheral boundary area of the second cell on the basis of the measurement report for each of the plurality of second cells located in the first cell, and determines whether to include the frequency information of the first cell in setting information of the frequency priority degree parameter set in the second cell on the basis of the detection result of the discontinuous boundary area.SELECTED DRAWING: Figure 1

Description

The present invention relates to a system, a management device, a method and a program for detecting a discontinuous service area in an overlay cell configuration and designing a wireless network based on the detection.

In recent years, as a countermeasure against disasters and out-of-service areas, from mobile base stations in the sky built into aircraft such as aircraft, artificial satellites, HAPS, balloons, helicopters, and drones, to the ground, water, or low altitude air. The expansion of the three-dimensional large zone cell (first cell) to be formed is considered to be effective. In an overlay cell configuration in which ground cells (second cell) such as normal macro cells and small cells are superimposed in this large zone cell, the frequency utilization efficiency is expanded by operating the large zone cell using the same frequency as the ground cell. can do.

In Non-Patent Documents 1 and 2, the procedure for initial connection (attachment) from the UE (mobile station) used by the user to the cell and the cell selection (reselection) from the idle UE (mobile station) are described. The procedure for doing so is disclosed.

3GPP TS 23.401 V16.4.0 (2019-09) 3GPP TS 23.502 V15.2.0 Release 15

The overlay cell configuration has the following problems. For example, the diameter of a large zone cell on the ground (footprint diameter) is about several tens of kilometers to several hundreds of kilometers, and the diameter is several kilometers to several tens of kilometers, which is about 10 times that of a macrocell, which is a relatively large above-ground cell. Further, while a ground base station (for example, a macro cell base station) covers a wide area with a radius of several hundred meters to a dozen kilometers with hundreds to thousands of stations, a base station in the sky forming a large zone cell. Covers a similar wide area with one station. Since the wide area is covered by one large zone cell in this way, the amount of communication traffic in the large zone cell increases, but the radio resources used by the base station in the sky for wireless communication with the UE are the radio resources of the ground base station. Since they are the same, the radio resources of the large zone cell may be exhausted, or the communication quality (throughput) of the UE located in the large zone cell may deteriorate. In order to avoid such exhaustion of radio resources of the large zone cell, the ground cell is preferentially reselected (or handed over between the ground cells) in the area where the ground cell exists in the large zone cell, and the ground cell exists. It is conceivable to design a wireless network with a policy of preferentially reselecting (or handing over to a large zone cell) a large zone cell in an area that does not.

However, in the design of the wireless network according to the above policy, the radio wave of the frequency of the terrestrial cell cannot be detected for some reason (for example, the radio wave from the terrestrial base station does not reach by the building) despite the area where the terrestrial cell exists. In some cases, only radio waves with the frequency of the zone cell can be detected. In this case, even if radio waves from the ground base station become available, they do not return to the ground cell and remain connected to the large zone cell, and there is a possibility that the exhaustion of radio resources in the large zone cell cannot be avoided.

The management device according to one aspect of the present invention sets the frequency priority parameter of the second cell in an overlay cell configuration in which the first cell and a plurality of second cells having a cell size smaller than that of the first cell are mixed. It is a management device to manage. This management device acquires measurement reports including reception intensities of mobile stations located in the plurality of second cells from the base stations in the plurality of second cells and from the base stations in the plurality of second cells. Based on the measurement report, for each of the plurality of second cells located in the first cell, a discontinuous boundary area in which the other second cells are not continuous in the outer peripheral boundary area of the second cell is detected. Means and means for determining whether or not to include the frequency information of the first cell in the setting information of the frequency priority parameter set in the second cell based on the detection result of the discontinuous boundary area. To be equipped.
A method according to another aspect of the present invention sets the frequency priority parameter of the second cell in an overlay cell configuration in which the first cell and a plurality of second cells having a cell size smaller than that of the first cell are mixed. It is a method of management. In this method, a measurement report including the reception intensity of the mobile stations located in the plurality of second cells is acquired from the base stations of the plurality of second cells, and is acquired from the base stations of the plurality of second cells. Based on the measurement report, for each of the plurality of second cells located in the first cell, a discontinuous boundary area in which the other second cells are not continuous in the outer peripheral boundary area of the second cell is detected. Based on the detection result of the discontinuous boundary area, it is determined whether or not to include the frequency information of the first cell in the setting information of the frequency priority parameter set in the second cell. include.
The program according to still another aspect of the present invention sets the frequency priority parameter of the second cell in an overlay cell configuration in which the first cell and a plurality of second cells having a cell size smaller than that of the first cell are mixed. It is a program executed by a computer or a processor provided in the management device that manages the frequency. This program includes a program code for acquiring a measurement report including reception intensities of mobile stations located in the plurality of second cells from the base stations of the plurality of second cells, and the base stations of the plurality of second cells. Based on the measurement report obtained from the above, for each of the plurality of second cells located in the first cell, a discontinuous boundary area in which the other second cells are not continuous in the outer peripheral boundary area of the second cell is defined. Whether or not to include the frequency information of the first cell in the setting information of the frequency priority parameter set in the second cell based on the program code for detection and the detection result of the discontinuous boundary area. Includes program code to determine.

In the management device, the method, and the program, for each of the plurality of second cells located in the first cell, the ratio of the peripheral length of the discontinuous boundary area to the peripheral length of the outer peripheral boundary area of the second cell. Is equal to or greater than a predetermined threshold value, and the frequency of the first cell is added to the setting information of the frequency priority parameter for the second cell in which the ratio of the circumference of the discontinuous boundary area is equal to or greater than the threshold value. Even if the frequency information of the first cell is not included in the setting information of the frequency priority parameter for the second cell in which the ratio of the circumference of the discontinuous boundary area is smaller than the threshold value, including the information of good.
The management device may be a network management system (NMS) that manages a mobile communication network including the base station of the first cell and the base stations of the plurality of second cells.
The management device may be an MME (mobile management entity) connected to a core network to which the base station of the first cell is connected, or the management device in a fifth generation or subsequent generation mobile communication system. It may be an AMF (Access and Mobile Management Function) to which the base station of the first cell is connected, or a core network device other than the AMF.

The communication system according to still another aspect of the present invention includes the management device, the first cell base station forming the first cell, and the plurality of second cell bases forming the plurality of second cells. Including stations.
In the communication system, the first cell base station may be a base station in which at least an antenna is installed in an air vehicle capable of moving or flying over the sky.
In the communication system, all or a part of the plurality of second cell base stations may use frequencies different from each other.
In the communication system, the plurality of second cell base stations have a second cell base station having the same frequency that uses the same frequency as the first cell base station and a different frequency that uses a frequency different from that of the first cell base station. It may include a second cell base station.
In the communication system, the second cell base station having the same frequency has at least an antenna installed in a small cell base station installed on the ground or water or an air vehicle flying at an altitude lower than that of the first cell base station. It is a small cell base station, and the second cell base station having a different frequency has at least an antenna installed in a macro cell base station installed on the ground or water or an air vehicle flying at an altitude lower than that of the first cell base station. The first cell base station may be a base station in which at least an antenna is arranged at the same position as or higher than the second cell base station.
In the communication system, the first cell base station may be a macro cell base station, and the second cell base station having the same frequency and the second cell base station having different frequencies may be small cell base stations, respectively.

According to the present invention, a change in the operating status of a wireless network is estimated by detecting a discontinuous boundary area in which the other second cells are not continuous among a plurality of small-sized second cells in an overlay cell configuration. be able to. Moreover, based on the detection result of the discontinuous boundary area where the change in the operation status of the wireless network can be estimated, the frequency priority in the second cell is given only to the second cell including the discontinuous boundary area among the plurality of second cells. The frequency parameter setting information can include information on the frequency of the large-sized first cell. Therefore, even if the operating status of the wireless network in the overlay cell configuration changes, it is possible to prevent the exhaustion of wireless resources in the large-sized first cell.

An explanatory diagram showing an example of a schematic configuration of a mobile communication system having an overlay cell configuration in which a large zone cell and a plurality of ground cells are arranged according to an embodiment of the present invention. The sequence diagram which shows an example of the control of the frequency priority parameter set in the ground cell in the overlay cell configuration of the communication system which concerns on embodiment. (A) to (c) are explanatory diagrams showing an example of creating a coverage area estimation map by a plurality of ground cells using different frequencies. Explanatory drawing which shows an example of the calculation method of the ratio of the peripheral length of a discontinuous boundary area to the total peripheral length of the outer peripheral boundary area of a ground cell.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, an embodiment of the present invention will be described on the premise of application to a mobile communication system conforming to next-generation standard specifications such as LTE / LTE-Advanced and 5th generation, but similar cell configurations and physical channel configurations will be described. The concept of the present invention can be applied to any system as long as it is used.

First, the overall configuration of a mobile communication system to which the present invention can be applied will be described.
FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a mobile communication system having an overlay cell configuration in which a large zone cell 10A and a plurality of ground cells 20A according to an embodiment of the present invention are arranged. As a measure against disasters and elimination of out-of-service areas, it is effective to deploy a large zone cell 10A as a large-sized first cell formed from the air-floating type communication relay device 15 toward the ground or water. Further, as a countermeasure against the rapidly increasing mobile communication traffic in the large zone cell 10A, it is effective to apply an overlay cell configuration in which a plurality of ground cells 20A are superimposed in the large zone cell 10A.

In FIG. 1, the terrestrial cells 20A as a plurality of second cells are used for wireless communication with a user terminal device (hereinafter, also referred to as “UE”) which is a mobile station, and the frequency (frequency band) A (f _{HAPS) of the large zone cell 10A is used.} A frequency (frequency band) B (f ₁ ) different from that of) is used. The plurality of ground cells 20A may be a plurality of cells in which a _{plurality of frequencies B (f 1} , f ₂ , f _{3, ...) Different from each other are used.} Further, the plurality of ground cells 20A include a plurality of cells formed in the same area by a single ground cell base station and using a plurality of _{different frequencies B (f 1} , f ₂ , f _{3, ...).} But it may be. Further, the plurality of terrestrial cells 20A have a terrestrial cell (for example, a small cell) having the same frequency (frequency band) as the large zone cell 10A for wireless communication with the UE, and a frequency (frequency) different from that of the large zone cell 10A for wireless communication with the UE. It may also include ground cells (eg, macrocells) of different frequencies in which the band) is used.

In the illustrated example, the cell configuration is such that the entire plurality of ground cells 20A are included in the large zone cell 10A, but a part of the plurality of ground cells 20A is partially included in the large zone cell 10A. It may be duplicated.

Further, the plurality of ground cells 20A may be a mixture of small cells and macro cells. In this case, a part of the small cell may overlap with the macro cell, or the entire small cell may be located in the macro cell.

The frequencies A and B used in the cells 10A and 20A may be, for example, a frequency in the microwave band of 300 MHz to 30 GHz or a frequency in the millimeter wave band higher than 30 GHz. Further, the frequency A may be 700 MHz to 1 GHz, and the frequency B may be a frequency higher than 1 GHz.

In FIG. 1, the mobile communication system of the present embodiment is a communication system compliant with next-generation standard specifications such as LTE (Long Term Evolution) / LTE-Advanced or 5th generation, and is mounted on the communication relay device 15. A movable large zone cell base station (sky base station) 10 as a first cell base station, and a plurality of second cell base stations fixedly arranged in a large zone cell 10A which is a wireless communication area of the large zone cell base station 10. The ground cell base station 20 is provided. The large zone cell base station 10 and the ground cell base station 20 are, for example, eNodeB (eNB) or gNodeB (gNB).

The plurality of terrestrial cell base stations 20 use, for example, a frequency B (f ₁ ) _{different from the frequency A (f HAPS) of the large zone cell base station 10 for wireless communication with the UE.} The plurality of ground cell base stations 20 may use a plurality of frequencies B (f ₁ , f ₂ , f ₃ , ...) Different from each other. Further, the ground cell base station 20 may form a plurality of ground cells having a _{plurality of frequencies (f 1} , f ₂ , f _{3, ...) Different from each other in the same area.} Further, the plurality of terrestrial cell base stations 20 are a terrestrial cell base station (for example, a small cell base station) that forms a terrestrial cell having the same frequency (frequency band) as the large zone cell 10A for wireless communication with the UE, and the UE. It may include a ground cell base station (for example, a macro cell base station) that forms a ground cell having a different frequency in which a frequency (frequency band) different from that of the large zone cell 10A is used for wireless communication.

In the present embodiment, the same telecommunications carrier (carrier) operates and manages the mobile communication network of frequency A and the mobile communication network of frequency B to provide the mobile communication service. In order to identify the mobile communication network of frequency A and the mobile communication network of frequency B of the same communication carrier (carrier) from each other, the identification information of the mobile communication networks different from each other in the mobile communication networks of frequency A and frequency B ( PLMN: Public land mobile network number) is assigned and set.

The large zone cell base station 10 is a base station (for example, eNodeB, gNodeB) as a relay communication station mounted on an airborne communication relay device 15 composed of an air vehicle that can move in the sky, and is a feeder on the mobile communication network side. The wireless communication of the link FL and the wireless communication of the service link SL on the mobile station side can be relayed.

Note that FIG. 1 shows an example in which the relay communication station mounted on the communication relay device 15 in the sky is the large zone cell base station 10, but the large zone cell base station 10 is provided in the gateway station 70 on the ground side. Alternatively, it may be provided in a device connected to the gateway station 70 on the ground side. In this case, the relay communication station mounted on the communication relay device 15 performs wireless communication of the feeder link FL with the large zone cell base station 10 and wireless communication of the service link SL with the UE (mobile station). Functions as a relay repeater.

Further, among the components of the large zone cell base station 10, at least an antenna and a wireless device of a service link that wirelessly communicates with the UE may be mounted on the communication relay device 15 and a baseband processing unit may be provided on the ground side.

Further, FIG. 1 shows an example in which the communication relay device 15 equipped with the large zone cell base station 10 is an airship as an airship capable of moving over the sky, but the communication relay device 15 can move or fly over the sky. Drone, balloon, aircraft, helicopter, solar plane type HAPS ("high altitude platform station" or "high altitude pseudo satellite") or LAPS ("low altitude platform station" or "low altitude pseudo satellite"), airship type It may be another unmanned or manned aircraft such as HAPS or LAPS, an artificial satellite. Further, the communication relay device 15 is controlled to move to a predetermined position in the sky located at the time of operation for wireless relay, and then stay at that position or circulate in a predetermined range of flight space including the position. You may.

The aircraft is located in the airspace at an altitude of 100 [km] or less from the ground, sea surface, or water surface such as a river or lake, by autonomous control or external control, or by the control of the operator boarding the aircraft. It may be controlled as follows. Further, the flight airspace of the flying object may be a stratospheric airspace having an altitude of 11 [km] or more and 50 [km] or less. Further, the flight airspace of the flying object may be an airspace having an altitude of 15 [km] or more and 25 [km] or less in which the weather conditions are relatively stable, and particularly an airspace having an altitude of approximately 20 [km]. May be good.

Further, the large zone cell base station 10 is a base station installed at a position higher than the ground cell base station (second base station) 20 (including the position in the atmosphere and the position in outer space outside the atmosphere). You may. The ground cell base station 20 may be installed on the ground or on the water, or may be installed on an aircraft flying at an altitude lower than that of the large zone cell base station 10. Further, the first cell base station (large zone cell base station) 10 may be a macro cell base station, and the second cell base station 20 having a frequency different from that of the macro cell base station may be a small cell base station.

Here, the macro cell base station is a high-power base station that covers a ground cell that is usually installed outdoors in a mobile communication network and is a wide area with a radius of about several hundred meters to several kilometers. The macrocell base station 30 is connected to another base station by, for example, a wired communication line, and can communicate with a predetermined communication interface. In addition, the macro cell base station is connected to the core network of the mobile communication network via a communication line such as a line termination device and a dedicated line, and can communicate with various nodes such as a server on the core network by a predetermined communication interface. It has become.

Unlike wide-area macrocell base stations, small cell base stations have a wireless communication range of several meters to several hundreds of meters, and have a small output that can be installed inside buildings such as ordinary homes, stores, and offices. Base station. Small cell base stations are also connected to the core network of the mobile communication network via line termination devices and communication lines such as ADSL (Asymmetric Digital Subscriber Line) lines and broadband public communication lines such as optical lines, and servers on the core network. It is possible to communicate with various nodes such as devices by a predetermined communication interface.

The ground cell base station 20 in the large zone cell 10A may be a base station installed on the ground or on the water, or may be a low altitude flying object such as a drone or a balloon flying at an altitude lower than that of the large zone cell base station 10. It may be an installed base station.

In FIG. 1, the first mobile station, UE 41, is a user terminal device (MUE) located in the large zone cell 10A of frequency A and connected to the large zone cell base station 10, via the large zone cell base station 10. It is in a state where wireless communication for telephone and data communication is possible.

The second mobile station, UE 42, is a user terminal device (SUE) located in the ground cell 20A of frequency B and connected to the ground cell base station 20, and is a telephone or data via the ground cell base station 20. Wireless communication for communication etc. is possible.

The UE 41 is located in the large zone cell 10A and is connected to the cell 10A. The UE 42 is located in the ground cell 20A and is connected to the cell 20A. In the UE 42', the ratio [%] of the discontinuous boundary area in which other ground cells located in the periphery in the outer peripheral boundary area of the ground cell, which will be described later, is not continuous among the plurality of ground cells 20A is a predetermined threshold value (Z [ %]) Above, the ground cell (hereinafter also referred to as "large zone cell frequency activation cell") 20A'shown by the broken line in the figure, which includes the frequency information of the large zone cell 10A in the frequency priority parameter setting information. It is connected to the ground cell 20A'in the area.

The ratio [%] of the discontinuous boundary area among the plurality of ground cells 20A is smaller than the predetermined threshold value (Z [%]), and the frequency information of the large zone cell 10A is not included in the frequency priority parameter setting information. The ground cell 20A is also referred to as a "large zone cell frequency inactivated cell". Further, in the explanation of this document, when the ground cell 20A and the ground cell 20A'are not distinguished, it is described as "ground cell 20A", and when the ground cell base station 20 and the ground cell base station 20A'are not distinguished, the ground cell base station 20A and the ground cell base station 20A'are not distinguished. Described as "ground cell base station 20". When UE 42 and UE 42'are not distinguished, it is described as "UE 42".

When UEs 41 and 42 are in the large zone cell 10A and the ground cell 20A, respectively, a predetermined communication method and wireless communication resource are provided between the large zone cell base station 10 and the ground cell base station 20 corresponding to the cells in the area. Can be used for wireless communication. Each of the UEs 41 and 42 is configured by using hardware such as a computer device having a CPU and a memory, an external communication interface unit for a core network, and a wireless communication unit, and the base station 10 and 42 are executed by executing a predetermined program. Wireless communication with 20 mag can be performed.

In the present embodiment, the large zone cell base station 10 and the terrestrial cell base station 20 are each configured by using hardware such as a computer device having a CPU and a memory, an external communication interface unit for a core network, and a wireless communication unit, respectively. By executing a predetermined program, various processes for controlling and managing the connection and disconnection of the UE to the cells 10A and 20A can be executed, and various processes such as handover of UEs 41 and 42 can be executed. , The control information including the setting information of the frequency priority parameter can be notified to the UEs 41 and 42, and the wireless communication with the UEs 41 and 42 can be performed using a predetermined communication method and wireless communication resources.

Each of the base stations 10 and 20 is a base station capable of wireless communication of an OFDM (Orthogonal Frequency Division Multiplexing) downlink to a UE which is a mobile station. The base stations 10 and 20 include, for example, an antenna, a radio signal path switching unit, a transmission / reception duplexer (DUP: Duplexer), a downlink radio reception unit and an OFDM (Orthogonal Frequency Division Multiplexing) demodulation unit, an uplink radio reception unit, and an SC-FDMA ( Single-Carrier Frequency-Division Multiple Access) Equipped with a demodulation unit, etc. Further, each of the base stations 10 and 20 includes an OFDM modulation unit, a downlink radio transmission unit, a control unit, and the like.

The SC-FDMA demodulation unit executes an SC-FDMA demodulation process on the received signal received by the uplink radio reception unit, and passes the demodulated data to the control unit. The OFDM modulation unit modulates the downlink signal data received from the control unit and transmitted to the UE in the cell of its own station by the OFDM method so that it is transmitted with a predetermined power. Further, when the base station receives information on a subframe to be stopped from transmission, for example, the OFDM modulation unit is controlled to stop downlink transmission only for a specific subframe in the wireless communication frame. The downlink radio transmission unit transmits the transmission signal modulated by the OFDM modulation unit via the transmission / reception duplexer, the radio signal path switching unit, and the antenna.

The control units of the base stations 10 and 20 are composed of, for example, a computer device, and control each unit or execute various processes by reading and executing a predetermined program. The control unit includes an external communication interface unit for the core networks 51 and 52, core network devices 61 and 62 such as MME (mobility management entity) devices and AMF (access and mobility management function) devices, and a network management system (NMS). For means for controlling and managing initial connection, reselection, disconnection, etc. of the UE cells 10A and 20A in cooperation with the management device 30 such as, and for handover of the UEs 41 and 42. It also functions as a means of performing processing. The MME device and the AMF device accommodate base stations (for example, eNodeB, gNodeB) 10 and 20, function as a gateway for control signals to and from the base station, and control the mobility of the UE.

In the present embodiment, the first core network 51 for the large zone cell base station 10 and the second core network 52 for the ground cell base station 20 are separately provided, but the large zone cell base station 10 and the ground are provided separately. A common core network may be provided in the cell base station 20, and a core network device accommodating the large zone cell base station 10 and a core network device accommodating the ground cell base station 20 may be separately provided in the common core network. .. Further, a common core network is provided for the large zone cell base station 10 and the ground cell base station 20, and a common core network device for accommodating the large zone cell base station 10 and the ground cell base station 20 is provided in the common core network. May be good.

Each of the base stations 10 and 20 can communicate with the management device 30 via the core network devices 61 and 62 such as the MME device of each of the core networks 51 and 52. For example, the large zone cell base station 10 can communicate with the management device 30 via the gateway station 70 and the core network device 61 of the first core network 51. The terrestrial cell base station 20 can communicate with the management device 30 via a predetermined interface and the core network device 62 of the second core network 52.

The communication system of the present embodiment includes at least a management device 30, and may include base stations 10 and 20, respectively. The management device 30 is composed of, for example, a single computer device or a plurality of computer devices, and by reading and executing a predetermined program, a process for managing or controlling a base station and a UE in a mobile communication system having an overlay cell configuration is performed. Run. The management device 30 also functions as the means of the following (1) to (3).

(1) A means for acquiring a measurement report (MR) including a reception intensity of a UE (mobile station) 42 located in a plurality of ground cells (second cell) 20A from a ground cell base station 20 of a plurality of ground cells 20A.
(2) Based on the measurement reports obtained from the ground cell base stations 20 of the plurality of ground cells 20A, for each of the plurality of ground cells 20A located in the large zone cell (first cell) 10A, in the outer boundary area of the ground cell 20A. A means for detecting a discontinuous boundary area in which the other second cells are not continuous.
(3) A means for determining whether or not to include the information of the frequency A of the large zone cell 10A in the setting information of the frequency priority parameter set in the ground cell 20A based on the detection result of the discontinuous boundary area.

The management device 30 also functions as the means of the following (4) and (5).
(4) For each of the plurality of ground cells 20A located in the large zone cell 10A, is the ratio of the peripheral length L2 of the discontinuous boundary area to the peripheral length L of the outer peripheral boundary area of the ground cell 20A equal to or more than a predetermined threshold value Z? A means of determining whether or not.
(5) The frequency priority parameter setting information for the ground cell 20A'in which the ratio of the peripheral length L2 of the discontinuous boundary area is equal to or greater than the threshold value Z includes the information of the frequency A (f _HAPS ) of the large zone cell 10A. A means for not including _{the frequency A (f HAPS} ) information of the large zone cell 10A in the setting information of the frequency priority parameter for the ground cell 20A in which the ratio of the peripheral length L2 of the discontinuous boundary area is smaller than the threshold value Z.

In the communication system having the overlay cell configuration, the diameter (footprint diameter) of the large zone cell 10A on the ground is about several tens of kilometers to several hundreds of kilometers, and the diameter is a relatively large ground cell of several hundreds to several hundreds of kilometers. It is about 10 times as large as a certain macro cell 30A. Further, the macro cell base station 30 covers a wide area with a radius of a dozen kilometers with hundreds to thousands of stations, whereas the large zone cell base station 10 in the sky forming the large zone cell 10A covers a similar wide area. Cover with one station. Since the wide area is covered by one large zone cell in this way, the communication traffic volume of the large zone cell 10A increases, but the radio resource used by the large zone cell base station 10 in the sky for wireless communication with the UE 41 is a ground cell base. Since it is the same as the radio resource of the station 20, the radio resource in the large zone cell 10A may be exhausted. In addition, the communication quality (throughput) of the UE 41 located in the large zone cell 10A may deteriorate. Further, when the communication traffic volume of the large zone cell 10A exceeds the processing capacity of the radio of the large zone cell base station 10, the handover to the large zone cell 10A fails, or the reselection of the large zone cell 10A by the idle UE fails. There is also a risk of doing so.

Therefore, in the present embodiment, as shown below, only the UEs in the ground cell that satisfy the predetermined condition among the plurality of ground cells 20A can be handed over to the large zone cell 10A (or the large zone cell 10A). (To be able to reselect). Specifically, for example, among a plurality of cells 20A, a large zone cell frequency activation cell 20A in which the ratio of the discontinuous boundary area in which the other second cells are not continuous in the outer peripheral boundary area of the ground cell 20A is equal to or more than a predetermined threshold value. Only the UE 42'in the'area'can be handed over to the large zone cell 10A (or the large zone cell 10A can be reselected). As a result, it is possible to prevent the exhaustion of wireless resources in the large zone cell 10A even when the operating status of the wireless network in the overlay cell configuration changes, and it is possible to suppress a decrease in communication quality (for example, throughput) in the large zone cell 10A.

FIG. 2 is a sequence diagram showing an example of control of a frequency priority parameter set in the ground cell 20A in the overlay cell configuration of the communication system according to the present embodiment.
2, the terrestrial cell base station 20, a plurality of UE42 located in the each of the cells 20A, frequency _A large Zonseru 10A _{(f HAPS)} other than the frequency _{B (f 1, f 2,} f 3, ··· ) Is received and collected (S101), and the measurement report (MR) collected from each UE 42 is reported to the management device (NMS) 30 (S102).

The management device 30 receives the MR arrival direction of each UE received from the plurality of ground cell base stations 20 in the large zone cell 10A (for example, the direction of the MR arrival direction based on the position of the antenna of the ground cell base station 20) and the direction of arrival of the MR. The area of cell 20A of each ground cell base station 20 is estimated based on the reception intensity, and a coverage area estimation map of the entire ground cell formed by a plurality of ground cells 20A in the large zone cell 10A is created (S103). The MR arrival direction of each UE can be calculated based on, for example, the position information of the antenna of the ground cell base station 20 and the position information of the current position of each UE (for example, the position information of GNSS).

Next, in the management device 30, based on the coverage area estimation map of the entire ground cell, for each of the plurality of ground cells 20A located in the large zone cell 10A, other ground cells are continuously connected in the outer peripheral boundary area of the ground cell 20A. A ground cell having a predetermined ratio of discontinuous boundary areas (discontinuous boundary area) is detected, and the ratio of the peripheral length L2 of the discontinuous boundary area to the peripheral length L of the outer peripheral boundary area of the ground cell 20A is determined. Large zone cell frequency activation cell) 20A'is identified (S104).

Next, the management device 30 positions the large zone cell frequency activation cell 20A'as the search target frequency in the ground cell base station 20'of the large zone cell frequency activation cell A'having the discontinuous boundary area of the predetermined ratio. Information on the frequency A (large zone cell frequency f _HAPS ) of the large zone cell 10A is transmitted (S105).

Next, when the management device 30 receives the reception result of receiving the signal of the _{large zone cell frequency f HAPS} from the ground cell base station _{20'that has received the information of the large zone cell frequency f HAPS (S106), the management device 30 receives the reception result of receiving the signal of the large zone cell frequency f HAPS. Decided to include the information of the large zone cell frequency f HAPS} in the setting information of the frequency priority parameter of 20', and made an additional request to add the _{information of the large zone cell frequency f HAPS} to the setting information of the frequency priority parameter. , Transmit to the ground cell base station 20'(S108).

On the other hand, the management device 30 sets the frequency priority parameter for the large zone cell frequency inactivating cell 20A (ground cell other than the large zone cell frequency activating cell 20A') which does not have a predetermined ratio of discontinuous boundary area. It is decided not to include the information of the large zone cell frequency f _{HAPS in the setting information.} By not including the information of the large zone cell frequency f _HAPS , it is possible to avoid unnecessary frequency search by the UE and prevent the occurrence of Measurement GAP that stops wireless communication with the terrestrial cell in which the UE is located.

When the ground cell base station 20'receives a _{request for adding information on the large zone cell frequency f HAPS from the management device 30, the ground cell base station 20'adds the information on the large zone cell frequency f HAPS} to the setting information for the frequency priority parameter (S109). The UE 42'is notified of the control information including the setting information of the frequency priority parameter (S110).

When the UE 42'receives the above control information from the ground cell base station 20', the UE 42'receives signals from peripheral base stations for a plurality of frequencies including the _{large zone cell frequency f HAPS based on the setting information in the frequency priority parameter.} do. Then, the UE 42'is handed over from the large zone cell frequency activation cell 20A'to the large zone cell or another ground cell 20A with the large zone cell base station 10 based on the reception result of the signal from the surrounding base station. The process is executed (S111), or the reselection process for reselecting the large zone cell frequency activation cell 20A'with the ground cell base station 20 of the large zone cell frequency activation cell 20A'is executed (S112). ..

In the control sequence of FIG. 2, steps S101 to S110 may be repeatedly executed at regular intervals. For example, the MRs of the ground cells 20A of a specific frequency are totaled at regular intervals, and based on the totaled results, the ground cells 20A'having a predetermined ratio of discontinuous boundary areas are specified, and the frequency of the ground cells 20A' is specified. Information on the large zone cell frequency f _HAPS may be added to the setting information of the priority parameter.

Table 1 shows an example of the frequency priority parameters and the operations of the UEs 42 and 42'in the large zone cell frequency inactivating cell 20A and the large zone cell frequency activating cell 20A', respectively. In the example of Table 1, respectively large Zonseru frequency inactivated cell 20A and the large Zonseru frequency activated cell 20A 'comprises two cells of frequencies f _1, f _2, adjacent to the ground cells of the frequency f ₃ .. Further, the frequency priority parameter at the time of connecting the UEs 42 and 42'is the handover parameter (MeasConfig). The frequency priority parameter at idle when the wireless connection is disconnected is the Reconnection parameter (SIB5).

3 (a) to 3 (c) show the creation of a coverage area estimation map by a plurality of ground cells 20A using _{different frequencies (f 1} , f ₂ , f _{3) (see step S103 of control in FIG. 2 above).} ) Is an explanatory diagram showing an example. In this example, as shown in FIG. 3A, a plurality of ground cells 20A having _{three different frequencies (f 1} , f ₂ , f _{3) are formed in the same area 200.} As shown in FIG. 3C, each ground cell 20A is an area where the reception intensity is equal to or higher than the predetermined out-of-range threshold value X [dBm], and the strong electric field area 20A (1) and the medium electric field are in order from the area closest to the base station. It is composed of an area 20A (2) and a weak electric field area 20A (3). The weak electric field area 20A (3) corresponds to the outer peripheral boundary area of the above-mentioned ground cell 20A, and the area outside the weak electric field area 20A (4) is the out-of-service area 20A (4). _{By superimposing the ground cells 20A of the three} frequencies (f ₁ , f ₂ , f 3) of FIG. 3 (a), the coverage of the ground cells 20A of a plurality of frequencies in the area 200 as shown in FIG. 3 (b). Area estimation map can be created.

FIG. 4 is an explanatory diagram showing an example of a method of calculating the ratio (L2 / L) of the peripheral length L2 of the discontinuous boundary area to the total peripheral length L of the outer peripheral boundary area 20C of the ground cell 20. Of the total peripheral length L of the outer peripheral boundary area 20C of the ground cell 20A in the figure, the portion of the length L1 where the other adjacent ground cells 20A overlap is the continuous boundary area, and the other ground cells 20A overlap. The portion of length L2 that is not provided is the discontinuous boundary area. The ratio [%] of the circumference L2 of the discontinuous boundary area to the circumference L of the outer peripheral boundary area of the ground cell 20A in the control step S104 of FIG. 2 described above can be calculated and estimated by, for example, L2 / L. ..

The determination of whether or not the cell is a ground cell including a predetermined ratio of discontinuous boundary areas is based on a specific index value in the KPI (Key Performance) such as the HO success rate and throughput acquired for the ground cell. You may go.

As described above, according to the present embodiment, the wireless network is configured by detecting a discontinuous boundary area in which other ground cells are not continuous among a plurality of small-sized ground cells (second cells) 20 in the overlay cell configuration. Changes in operational status can be estimated. Moreover, based on the detection result of the discontinuous boundary area in which the change in the operation status of the wireless network can be estimated, only the ground cell 20'including the discontinuous boundary area among the plurality of ground cells 20 is in the ground cell 20'. _{The frequency A (f HAPS} ) information of the large zone cell 10A can be included in the frequency priority parameter setting information. Therefore, it is possible to prevent the exhaustion of wireless resources in the large zone cell 10A even when the operating status of the wireless network in the overlay cell configuration changes.

In the present embodiment, the case of the overlay configuration of the large zone cell 10A and the ground cell 20A has been described, but the present invention is not limited to this configuration, and the present invention is applied to an overlay configuration of a plurality of cells having different sizes. be able to.

Further, in the present embodiment, the description has been made on the premise of application to LTE / LTE-Advanced, but downlink wireless communication, wireless communication frame, and OFDM of the OFDM (Orthogonal Frequency Division Multiplexing) method similar to LTE / LTE-Advanced. The concept of the present invention can be applied to any system as long as it is a system using symbols and the like, and is not limited to the transmitter and receiver configurations shown in the present embodiment.

In addition, the processing steps described herein and the components of a mobile communication system, a large zone cell base station (first cell base station), a ground cell base station (second cell base station), and a user terminal device (mobile station). Can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

Regarding hardware implementation, means such as a processing unit used to realize the above steps and components in an entity (for example, various wireless communication devices, Node B, terminal, hard disk drive device, or optical disk drive device) One or more application-specific ICs (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors , Controllers, microprocessors, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, computers, or combinations thereof.

For firmware and / or software implementation, means such as processing units used to implement the above components are programs (eg, procedures, functions, modules, instructions) that perform the functions described herein. , Etc.) may be implemented. Generally, any computer / processor readable medium that clearly embodies the firmware and / or software code is a means such as a processing unit used to implement the steps and components described herein. May be used to implement. For example, the firmware and / or software code may be stored in memory and executed by a computer or processor, for example, in a control device. The memory may be implemented inside the computer or processor, or may be implemented outside the processor. Further, the firmware and / or software code includes, for example, random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), and electrically erasable PROM (EEPROM). ), FLASH memory, floppy (registered trademark) discs, compact discs (CDs), digital versatile discs (DVDs), magnetic or optical data storage devices, etc. good. The code may be executed by one or more computers or processors, or the computers or processors may be made to perform functional embodiments described herein.

Further, the medium may be a non-temporary recording medium. Further, the code of the program may be read and executed by a computer, a processor, or another device or device machine, and the format thereof is not limited to a specific format. For example, the code of the program may be any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

Also, the description of the embodiments disclosed herein is provided to allow one of ordinary skill in the art to manufacture or use the disclosure. Various amendments to this disclosure will be readily apparent to those of skill in the art and the general principles defined herein are applicable to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be accepted in the broadest range consistent with the principles and novel features disclosed herein.

10 large zone cell base stations (1st base station, relay communication station)
10A large zone cell (1st cell)
15 Communication relay device 20, 20'Ground cell base station (second base station)
20A ground cell (second cell)
20A'Ground cell with a predetermined percentage of discontinuous boundary area 30 Management device 41, 42, 42' UE (mobile station)
51,52 core network 61,62 core network device 70 gateway station

Claims (12)

A management device that manages the setting of the frequency priority parameter of the second cell in an overlay cell configuration in which the first cell and a plurality of second cells having a cell size smaller than that of the first cell coexist.
A means for obtaining a measurement report including the reception intensity of mobile stations located in the plurality of second cells from the base stations in the plurality of second cells, and
Based on the measurement report obtained from the base stations of the plurality of second cells, for each of the plurality of second cells located in the first cell, another second cell is formed in the outer peripheral boundary area of the second cell. Means for detecting discontinuous boundary areas that are not continuous,
A means for determining whether or not to include the frequency information of the first cell in the setting information of the frequency priority parameter set in the second cell based on the detection result of the discontinuous boundary area is provided. A management device characterized by. In the management device of claim 1,
For each of the plurality of second cells located in the first cell, whether or not the ratio of the peripheral length of the discontinuous boundary area to the peripheral length of the outer peripheral boundary area of the second cell is equal to or more than a predetermined threshold value. Judge,
The frequency priority parameter setting information for the second cell in which the ratio of the circumference of the discontinuous boundary area is equal to or greater than the threshold value includes the frequency information of the first cell.
A management device characterized in that the frequency information of the first cell is not included in the setting information of the frequency priority parameter for the second cell in which the ratio of the circumference of the discontinuous boundary area is smaller than the threshold value. In the management device of claim 1 or 2, the management device is a network management system (NMS) that manages a mobile communication network including the base station of the first cell and the base stations of the plurality of second cells. A featured management device. It ’s a communication system,
The management device according to any one of claims 1 to 3, a first cell base station forming the first cell, and a plurality of second cell base stations forming the plurality of second cells. Communication system. In the communication system of claim 4,
The first cell base station is a communication system characterized in that at least an antenna is installed in an air vehicle capable of moving or flying over the sky. In the communication system of claim 4 or 5,
The second cell base station is a communication system characterized in that a plurality of second cells using a plurality of frequencies different from each other are formed in the same area. In the communication system according to any one of claims 4 to 6.
A communication system characterized in that all or a part of the plurality of second cell base stations use frequencies different from each other. In the communication system according to any one of claims 4 to 7.
The plurality of second cell base stations include a second cell base station having the same frequency that uses the same frequency as the first cell base station, and a second cell base station having a different frequency that uses a frequency different from that of the first cell base station. A communication system characterized by including. In the communication system of claim 8,
The second cell base station of the same frequency is a small cell base station installed on the ground or water, or a small cell base station in which at least an antenna is installed in an air vehicle flying at an altitude lower than that of the first cell base station. can be,
The second cell base station having a different frequency is a macro cell base station installed on the ground or water, or a macro cell base station in which an antenna is installed at least on an air vehicle flying at an altitude lower than that of the first cell base station.
The first cell base station is a communication system characterized in that the first cell base station is a base station in which at least an antenna is arranged at the same position as or higher than the second cell base station. In the communication system of claim 8,
A communication system characterized in that the first cell base station is a macro cell base station, and the second cell base station having the same frequency and the second cell base station having different frequencies are small cell base stations, respectively. A method of managing the setting of the frequency priority parameter of the second cell in an overlay cell configuration in which the first cell and a plurality of second cells having a cell size smaller than that of the first cell coexist.
Obtaining a measurement report including the reception intensity of the mobile stations located in the plurality of second cells from the base stations of the plurality of second cells, and
Based on the measurement report obtained from the base stations of the plurality of second cells, for each of the plurality of second cells located in the first cell, another second cell is formed in the outer peripheral boundary area of the second cell. Detecting discontinuous boundary areas that are not continuous
Based on the detection result of the discontinuous boundary area, the setting information of the frequency priority parameter set in the second cell includes determining whether or not to include the frequency information of the first cell. A method characterized by. A computer or processor provided in a management device that manages the setting of the frequency priority parameter of the second cell in an overlay cell configuration in which the first cell and a plurality of second cells having a cell size smaller than that of the first cell coexist. Is a program that runs on
A program code for acquiring a measurement report including reception strength of mobile stations located in the plurality of second cells from the base stations of the plurality of second cells, and
Based on the measurement report obtained from the base stations of the plurality of second cells, for each of the plurality of second cells located in the first cell, another second cell is formed in the outer peripheral boundary area of the second cell. Program code for detecting discontinuous boundary areas that are not continuous,
Based on the detection result of the discontinuous boundary area, the program code for determining whether or not to include the frequency information of the first cell in the setting information of the frequency priority parameter set in the second cell, and A program characterized by including.

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