JP7529341B2 - Base station device, mobile communication system, communication method, and communication program - Google Patents

Description

The present invention relates to a base station device, a mobile communication system, a communication method, and a communication program.

In mobile communication systems, there is a demand for reducing the power consumption of mobile terminals. For example, the mobile radio terminal disclosed in Patent Document 1 reduces the power consumption of the battery installed in the mobile radio terminal by determining and changing the cell search period based on the placement interval of base stations and the movement speed of the mobile radio terminal.

Patent No. 4011974

However, in the configuration disclosed in Patent Document 1, each mobile wireless terminal needs to have the function of determining and changing the cell search period based on the placement interval of base stations and the moving speed of the mobile wireless terminal. Therefore, there is a problem that mobile wireless terminals that do not have the above function cannot suppress power consumption unless the function is updated.

The objective of this disclosure is to provide a base station device, a mobile communication system, a communication method, and a communication program that solve the above-mentioned problems.

According to one embodiment, a base station device includes an acquisition unit that acquires a cell stay history of a mobile terminal present in a first cell that is within the wireless communication range of the base station device, the cell stay history including a stay time in the first cell; a determination unit that determines whether the mobile terminal has stayed in the first cell for more than a first predetermined period based on the cell stay history of the mobile terminal acquired by the acquisition unit; and an instruction unit that instructs the mobile terminal to switch the frequency of measuring the communication quality of each of the first cell and adjacent cells from a first frequency to a second frequency that is lower than the first frequency when it is determined that the mobile terminal has stayed in the first cell for more than the first predetermined period.

According to one embodiment, the communication method includes the steps of: acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of a base station device, the cell stay history including a stay time in the first cell; determining whether the mobile terminal has stayed in the first cell for more than a first predetermined period based on the acquired cell stay history of the mobile terminal; and, if it is determined that the mobile terminal has stayed in the first cell for more than the first predetermined period, instructing the mobile terminal to switch the frequency of measuring the communication quality of each of the first cell and adjacent cells from a first frequency to a second frequency that is lower than the first frequency.

According to one embodiment, the communication program causes a computer to execute the following processes: acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of a base station device, the cell stay history including a stay time in the first cell; determining whether the mobile terminal has stayed in the first cell for more than a first predetermined period based on the acquired cell stay history of the mobile terminal; and, if it is determined that the mobile terminal has stayed in the first cell for more than the first predetermined period, instructing the mobile terminal to switch the frequency of measuring the communication quality of each of the first cell and its adjacent cells from a first frequency to a second frequency that is lower than the first frequency.

According to the embodiment, it is possible to provide a base station device, a mobile communication system, a communication method, and a communication program that can reduce the power consumption of a mobile terminal without requiring a change to the functions of the mobile terminal.

2 is a block diagram showing a configuration example of a base station device according to the first embodiment; FIG. 11 is a block diagram showing a configuration example of a mobile communication system according to a second embodiment. 3 is a flowchart showing an example of an operation of the mobile communication system shown in FIG. 2 . FIG. 2 is a diagram showing an example of a cell stay history of a mobile terminal. FIG. 11 is a block diagram showing a configuration example of a mobile communication system according to a third embodiment. 6 is a block diagram showing an example of the configuration of a base station device provided in the mobile communication system shown in FIG. 5 . 6 is a flowchart showing an example of an operation of the mobile communication system shown in FIG. 5 . FIG. 2 is a diagram showing an example of a cell stay history of a mobile terminal.

The following describes the embodiments with reference to the drawings. Note that the drawings are simplified, and the technical scope of the embodiments should not be interpreted narrowly based on the descriptions in the drawings. Also, the same elements are given the same reference numerals, and duplicate explanations will be omitted.

In the following embodiments, when necessary for convenience, they will be divided into multiple sections or embodiments for explanation. However, unless otherwise specified, they are not unrelated to each other, and one is a partial or complete modification, application example, detailed explanation, supplementary explanation, etc. of the other. Furthermore, in the following embodiments, when the number of elements, etc. (including the number, numerical value, amount, range, etc.) is mentioned, it is not limited to that specific number, and may be more or less than the specific number, except when otherwise specified or when it is clearly limited in principle to a specific number.

Furthermore, in the following embodiments, the components (including operational steps, etc.) are not necessarily essential unless otherwise specified or considered to be clearly essential in principle. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., it is intended to include things that are substantially similar or approximate to the shape, etc., unless otherwise specified or considered to be clearly not essential in principle. The same applies to the numbers, etc. above (including numbers, numerical values, amounts, ranges, etc.).

<First embodiment>
FIG. 1 is a block diagram showing an example of the configuration of a base station device 11 according to the first embodiment.
1, the base station device 11 includes an acquisition unit 111, a determination unit 112, and an instruction unit 113. The base station device 11 is connected to a wired or wireless network 14 (not shown). Other base station devices, a management device (management server), a storage device, and the like are connected to the network 14 (none of which are shown).

The management device acquires the cell stay history of each mobile terminal from each base station device or the mobile terminal itself via the network 14, and stores it in a storage device. Then, when a base station device requests the cell stay history of a certain mobile terminal, the management device reads the cell stay history of the relevant mobile terminal from the storage device and transmits it to the base station device 11 that made the transmission request. The storage device may be provided inside the management device. Furthermore, the functions of the management device may be provided in each base station device.

The mobile terminal may be any terminal that performs wireless communication with the base station device 11, such as a mobile phone terminal, a smartphone, or a tablet terminal. The cell stay history is information on the duration of stay in cells in which the mobile terminal has been present from the past to the present (e.g., information on the start and end times of stay in each cell). For example, the cell stay history records a combination of the visited cell ID and the duration of stay in that cell in the order of stay. In the case of LTE (Long Term Evolution), the global-Cell-ID is used as the cell ID.

In the base station device 11, the acquisition unit 111 acquires the cell stay history of a mobile terminal that is present in a cell within the wireless communication range of the base station device 11 (hereinafter also referred to as the device itself).

In this embodiment, an example will be described in which the acquisition unit 111 acquires the cell stay history of the mobile terminal E1 present in the cell C1. In this case, the acquisition unit 111 transmits a transmission request for the cell stay history of the mobile terminal E1 to the management device via the network 14. When the management device receives the transmission request for the cell stay history from the acquisition unit 111, it reads the cell stay history of the mobile terminal E1 from the storage device and transmits it to the acquisition unit 111 that made the transmission request via the network 14. This allows the acquisition unit 111 to acquire the cell stay history of the mobile terminal E1. Note that when the function of the management device is provided in the base station device 11, the acquisition of the cell stay history by the acquisition unit 111 is performed inside the base station device 11.

The determination unit 112 determines whether or not the mobile terminal E1 has been staying (in range) in the cell C1 for more than a predetermined period T1 based on the cell stay history of the mobile terminal E1 acquired by the acquisition unit 111. A case where the mobile terminal E1 has been staying in the cell C1 for more than the predetermined period T1 is, for example, a case where the user carrying the mobile terminal E1 is staying at home. In such a case, it can be determined that the possibility of the mobile terminal E1 leaving the cell C1 within a short period of time is low. Note that the predetermined period T1 can, of course, be set to any period.

When it is determined that the mobile terminal E1 has been in the cell C1 for more than the predetermined period T1, the instruction unit 113 instructs the mobile terminal E1 to reduce the frequency of measuring the communication quality of the cell C1 and each of the adjacent cells (i.e., the frequency of cell searches). In the case of LTE, the instruction unit 113 instructs the mobile terminal E1 to reduce the frequency of Event A3 by using an RRC connection reconfiguration message.

For example, the instruction unit 113 instructs the mobile terminal E1 to switch the cell search frequency from frequency f1 to frequency f2 (f2<f1), which is a frequency lower than frequency f1. The instruction unit 113 may instruct the mobile terminal E1 to gradually decrease the cell search frequency from frequency f1 to frequency f2. Alternatively, the instruction unit 113 may instruct the mobile terminal E1 to stop the cell search. That is, the instruction unit 113 may instruct the mobile terminal E1 to switch the cell search frequency from frequency f1 to frequency f2 (f2=0).

When the mobile terminal E1 receives an instruction from the instruction unit 113 of the base station device 11 to reduce the frequency of cell searches, the mobile terminal E1 reduces the frequency of cell searches in accordance with the instruction. This reduces the power consumption of the mobile terminal E1. Note that the mobile terminal E1 may be an existing terminal, and there is no need to update its functions to reduce power consumption.

In this manner, the base station device 11 according to this embodiment determines whether the mobile terminal E1 has been staying (in range) in the cell C1, which is the wireless communication range of the base station device 11, for more than the predetermined period T1, based on the cell stay history of the mobile terminal E1. Then, when the base station device 11 determines that the mobile terminal E1 has been staying in the cell C1 for more than the predetermined period T1, it instructs the mobile terminal E1 to reduce the frequency of measuring the communication quality of the cell C1 and each of the adjacent cells (i.e., the frequency of cell searches). This allows the mobile terminal E1 to reduce the frequency of cell searches, thereby reducing power consumption without updating functions.

The base station device 11 includes a processor, a memory, and a storage device, which are not shown in the figure. The storage device stores a computer program that implements the processing of the communication method according to this embodiment. The processor then loads the computer program from the storage device into the memory and executes the computer program. In this way, the processor realizes the functions of the acquisition unit 111, the determination unit 112, and the instruction unit 113.

Alternatively, the acquisition unit 111, the determination unit 112, and the instruction unit 113 may each be realized by dedicated hardware. In addition, some or all of the components of the base station device 11 may be realized by general-purpose or dedicated circuits, processors, or combinations of these. These may be configured by a single chip, or may be configured by multiple chips connected via a bus. Some or all of the components of the base station device 11 may be realized by a combination of the above-mentioned circuits, etc., and programs. In addition, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field-Programmable Gate Array), etc. may be used as the processor.

In addition, when some or all of the components of the base station device 11 are realized by multiple information processing devices, circuits, etc., the multiple information processing devices, circuits, etc. may be centrally located or distributed. For example, the information processing devices, circuits, etc. may be realized as a client-server system, cloud computing system, etc., in which each is connected via a communication network. In addition, the functions of the base station device 11 may be provided in the form of SaaS (Software as a Service).

<Embodiment 2>
FIG. 2 is a block diagram showing an example of a configuration of a mobile communication system 1 according to the second embodiment.
2, the mobile communication system 1 includes a plurality of base station devices 11, a management device 12, a storage device 13, a network 14, and a mobile terminal E1. The plurality of base station devices 11, the management device 12, and the storage device 13 are each connected to each other via the network 14.

In this embodiment, an example will be described in which base station devices 11_1 and 11_2 are provided as multiple base station devices 11. Base station device 11_1 has a wireless communication range of cell C1 and can perform wireless communication with mobile terminals (including mobile terminal E1) located in cell C1. Base station device 11_2 has a wireless communication range of cell C2 and can perform wireless communication with mobile terminals located in cell C2.

The management device 12 acquires the cell stay history of each mobile terminal from each base station device 11_1, 11_2 or the mobile terminal itself via the network 14, and stores it in the storage device 13. Then, when a base station device requests the cell stay history of a certain mobile terminal, the management device 12 reads the cell stay history of the mobile terminal from the storage device 13 and transmits it to the base station device that made the transmission request. Note that the storage device 13 may be provided inside the management device 12. Furthermore, the functions of the management device 12 may be provided in each base station device 11_1, 11_2.

In base station device 11_1, acquisition unit 111 acquires the cell stay history of mobile terminal E1 that is present in cell C1, which is the wireless communication range of base station device 11_1.

In addition, in this embodiment, a case will be described in which mobile terminal E1 is present in cell C1, which is the wireless communication range of base station device 11_1. In this case, acquisition unit 111 transmits a request to transmit the cell stay history of mobile terminal E1 to management device 12 via network 14. When management device 12 receives the request to transmit the cell stay history from acquisition unit 111, it reads out the cell stay history of mobile terminal E1 from storage device 13 and transmits it to acquisition unit 111 that made the transmission request via network 14. This allows acquisition unit 111 to acquire the cell stay history of mobile terminal E1. Note that when the function of management device 12 is provided in base station device 11_1, acquisition of the cell stay history by acquisition unit 111 is performed inside base station device 11_1.

The determination unit 112 determines whether or not the mobile terminal E1 has been staying (in range) in the cell C1 for more than a predetermined period T1 based on the cell stay history of the mobile terminal E1 acquired by the acquisition unit 111. A case where the mobile terminal E1 has been staying in the cell C1 for more than the predetermined period T1 is, for example, a case where the user carrying the mobile terminal E1 is staying at home. In such a case, it can be determined that the possibility of the mobile terminal E1 leaving the cell C1 within a short period of time is low. Note that the predetermined period T1 can, of course, be set to any period.

When it is determined that the mobile terminal E1 has been in the cell C1 for more than the predetermined period T1, the instruction unit 113 instructs the mobile terminal E1 to reduce the frequency of measuring the communication quality of the cell C1 and each of its adjacent cells (i.e., the frequency of cell searches).

For example, the instruction unit 113 instructs the mobile terminal E1 to switch the cell search frequency from frequency f1 to frequency f2 (f2<f1), which is a frequency lower than frequency f1. The instruction unit 113 may instruct the mobile terminal E1 to gradually decrease the cell search frequency from frequency f1 to frequency f2. Alternatively, the instruction unit 113 may instruct the mobile terminal E1 to stop the cell search. That is, the instruction unit 113 may instruct the mobile terminal E1 to switch the cell search frequency from frequency f1 to frequency f2 (f2=0).

Having received an instruction from the instruction unit 113 of the base station device 11_1 to reduce the frequency of cell searches, the mobile terminal E1 reduces the frequency of cell searches in accordance with the instruction. This reduces power consumption through the cell search of the mobile terminal E1. Here, the mobile terminal E1 may be an existing one, and there is no need to update its functions to reduce power consumption. Note that if the mobile terminal E1 starts moving while the cell search is stopped and is no longer able to receive radio waves from cell C1, it selects the best cell at that time through a reconnection procedure or a new call.

In this manner, in the mobile communication system 1 according to the present embodiment, the base station device 11_1 determines whether the mobile terminal E1 has been staying (in) the cell C1, which is the wireless communication range of the base station device 11_1, for more than the predetermined period T1, based on the cell stay history of the mobile terminal E1. Then, when the base station device 11_1 determines that the mobile terminal E1 has been staying in the cell C1 for more than the predetermined period T1, it instructs the mobile terminal E1 to reduce the frequency of measuring the communication quality of the cell C1 and each of the adjacent cells (i.e., the frequency of cell searches). This allows the mobile terminal E1 to reduce the frequency of cell searches, thereby reducing power consumption without updating functions.

The configuration and operation of base station device 11_2 are the same as those of base station device 11_1, and therefore will not be described here. In addition, in this embodiment, the mobile communication system 1 is described as having two base station devices 11, but this is not limited to this. The mobile communication system 1 can have any number of base station devices 11. In this case, the configuration and operation of each base station device 11 are the same as those of base station device 11_1.

(flowchart)
Next, the operation of the mobile communication system 1 will be described with reference to FIG.
FIG. 3 is a flowchart showing an example of the operation of the mobile communication system 1.

In this embodiment, a case will be described in which mobile terminal E1 is present in cell C1, which is the wireless communication range of base station device 11_1. Base station device 11_1 also stores information (procedures) indicating the progress of wireless communication connection processing, handover processing, etc., for each mobile terminal (including mobile terminal E1) present in cell C1.

First, the mobile terminal E1 stabilizes the wireless communication connection state with the base station device that manages the serving cell (step S101). In this example, the mobile terminal E1 stabilizes the wireless communication connection state with the base station device 11_1 that manages the serving cell C1.

When the base station device 11_1 detects that the wireless communication state of the mobile terminal E1 has stabilized, it first starts a timer (step S102). After the timer is started, when a predetermined period T0 has elapsed and the timer times out (step S103), the base station device 11_1 acquires the cell stay history of the mobile terminal E1 at the time of the timeout (step S104).

The method of acquiring the cell stay history has already been explained. Specifically, base station device 11_1 transmits a request to transmit the cell stay history of mobile terminal E1 to management device 12 via network 14. When management device 12 receives the request to transmit the cell stay history from base station device 11_1, it reads out the cell stay history of mobile terminal E1 from storage device 13 and transmits it to base station device 11_1 that made the transmission request via network 14. This allows base station device 11_1 to acquire the cell stay history of mobile terminal E1. Note that if the functionality of management device 12 is provided in base station device 11_1, acquisition of the cell stay history by base station device 11_1 is performed within its own device.

Base station device 11_1 determines the period during which mobile terminal E1 stayed in cell C1 (cell stay period) from the acquired cell stay history.

For example, if the cell stay period of the mobile terminal E1 is equal to or shorter than the predetermined period T1 (NO in step S105), the process returns to step S102. That is, the base station device 11_1 periodically refers to the cell stay history of the mobile terminal E1 while the mobile terminal E1 is present in the cell C1.

On the other hand, if the stay period in cell C1 exceeds the predetermined period T1 (YES in step S105), base station device 11_1 instructs mobile terminal E1 to reduce the frequency of measuring the communication quality of cell C1 and its adjacent cells (step S106). That is, base station device 11_1 instructs mobile terminal E1 to reduce the frequency of cell searches.

Figure 4 is a diagram showing an example of the cell stay history of mobile terminal E1. Referring to the cell stay history in Figure 4, mobile terminal E1 first stays in cell C1 for 10 seconds, then stays in cell C2 for 10 seconds, and has stayed in cell C1 for 4000 seconds up to the present. If the predetermined period T1 is set to 3500 seconds, the period during which mobile terminal E1 stays in cell C1 will exceed the predetermined period T1, so base station device 11_1 instructs mobile terminal E1 to reduce the frequency of cell searches.

For example, base station device 11_1 instructs mobile terminal E1 to switch the cell search frequency from frequency f1 to frequency f2 (f2<f1), which is lower than frequency f1. Base station device 11_1 may also instruct mobile terminal E1 to gradually decrease the cell search frequency from frequency f1 to frequency f2. Alternatively, base station device 11_1 may instruct mobile terminal E1 to stop cell search. In other words, base station device 11_1 may instruct mobile terminal E1 to switch the cell search frequency from frequency f1 to frequency f2 (f2=0).

Having received an instruction from base station device 11_1 to reduce the frequency of cell searches, mobile terminal E1 reduces the frequency of cell searches in accordance with the instruction (step S107). This reduces the power consumption of mobile terminal E1. Here, mobile terminal E1 may be an existing terminal, and there is no need to update its functions to reduce power consumption.

If mobile terminal E1 starts moving while the cell search is stopped and is no longer able to receive radio waves from cell C1, it will select the best cell at that time using a reconnection procedure or a new call.

In this manner, in the mobile communication system 1 according to the present embodiment, the base station device 11_1 determines whether the mobile terminal E1 has been staying (in) the cell C1, which is the wireless communication range of the base station device 11_1, for more than the predetermined period T1, based on the cell stay history of the mobile terminal E1. Then, when the base station device 11_1 determines that the mobile terminal E1 has been staying in the cell C1 for more than the predetermined period T1, it instructs the mobile terminal E1 to reduce the frequency of measuring the communication quality of the cell C1 and each of the adjacent cells (i.e., the frequency of cell searches). This allows the mobile terminal E1 to reduce the frequency of cell searches, thereby reducing power consumption without updating functions.

<Third embodiment>
Fig. 5 is a block diagram showing a configuration example of a mobile communication system 2 according to embodiment 3. As shown in Fig. 5, the mobile communication system 2 includes a plurality of base station devices 21, a management device 22, a storage device 23, a network 24, and a mobile terminal E1. The plurality of base station devices 21, the management device 22, and the storage device 23 are each connected via the network 24.

In this embodiment, an example will be described in which base station devices 21_1 to 21_3 are provided as the multiple base station devices 21. Base station device 21_1 has a wireless communication range of cell C1 and can perform wireless communication with mobile terminals (including mobile terminal E1) located in cell C1. Base station device 21_2 has a wireless communication range of cell C2 and can perform wireless communication with mobile terminals located in cell C2. Base station device 21_3 has a wireless communication range of cell C3 and can perform wireless communication with mobile terminals located in cell C3.

In addition, in this embodiment, an example is described in which the cell radius of cells C1 and C2 is small (i.e., the wireless communication range of base station devices 21_1 and 21_2 is narrow), and the cell radius of cell C3 is larger than that of cells C1 and C2 (i.e., the wireless communication range of base station device 21_3 is wide). Note that cell C3 includes all or part of the communication range of cell C2. Hereinafter, cells C1 and C2 are also referred to as pico cells C1 and C2, and cell C3 is also referred to as macro cell C3.

The configurations of the management device 22, storage device 23, and network 24 are similar to those of the management device 12, storage device 13, and network 14, respectively, and therefore will not be described.

Figure 7 is a block diagram showing an example of the configuration of base station device 21_1. Note that the configurations of base station devices 21_2 and 22_3 are similar to those of base station device 21_1, so their explanations are omitted.

As shown in FIG. 7, base station device 21_1 includes an acquisition unit 211, a determination unit 212, and an instruction unit 213. The acquisition unit 211 acquires the cell stay history of mobile terminal E1 present in cell C1, which is the wireless communication range of base station device 21_1 (hereinafter also referred to as its own device). The method of acquiring the cell stay history by the acquisition unit 211 is similar to the method of acquiring the cell stay history by the acquisition unit 111, and therefore a description thereof will be omitted.

The determination unit 212 determines whether the number of times that the mobile terminal E1 stays in cell C1 per predetermined period T2 (cell stay count) is equal to or greater than a predetermined number, based on the cell stay history of the mobile terminal E1 acquired by the acquisition unit 211. An example of a case in which the number of times that the mobile terminal E1 stays in a cell per predetermined period T2 is equal to or greater than a predetermined number is when the mobile terminal E1 performs excessive handover processing between cell C1 and an adjacent cell within a short period of time. This phenomenon is likely to occur when the cell radius of the cell C1 in which the mobile terminal E1 is located is small. Naturally, the predetermined period T2 can be set to any period.

When it is determined that the number of cell stays of the mobile terminal E1 per predetermined period T2 is equal to or greater than a predetermined number, the instruction unit 213 instructs the mobile terminal E1 to select, as the handover destination, a cell having a larger cell radius than the cell C1 among the multiple candidate cells for the handover destination. More preferably, the instruction unit 213 instructs the mobile terminal E1 to select, as the handover destination, a cell having the largest cell radius among the multiple candidate cells for the handover destination.

When the mobile terminal E1 receives an instruction from the instruction unit 213 of the base station device 21_1 to select a cell with a larger cell radius as the handover destination, the mobile terminal E1 switches the communication target to a base station device whose communication range is a cell with a larger cell radius than cell C1 in accordance with the instruction. More preferably, the mobile terminal E1 switches the communication target to a base station device whose communication range is the cell with the largest cell radius among the multiple candidate handover destination cells.

A mobile terminal E1 located in a cell with a large cell radius is less likely to perform handover processing multiple times in a short period of time compared to when the mobile terminal E1 is located in a cell with a small cell radius. This reduces the power consumption due to the handover processing of the mobile terminal E1. Here, the mobile terminal E1 may be an existing terminal, and there is no need to update its functions.

In this manner, in the mobile communication system 2 according to the present embodiment, the base station device 21_1 determines whether the number of cell stays of the mobile terminal E1 per predetermined period T2 is equal to or greater than a predetermined number of times, based on the cell stay history of the mobile terminal E1. Then, when the base station device 21_1 determines that the number of cell stays of the mobile terminal E1 per predetermined period T2 is equal to or greater than the predetermined number of times, it instructs the mobile terminal E1 to set a cell with a larger cell radius than the cell C1 as the handover destination. This allows the mobile terminal E1 to reduce the frequency of handover processing, thereby reducing power consumption without updating functions.

The configuration and operation of base station devices 21_2 and 21_3 are the same as those of base station device 21_1, and therefore will not be described here. In addition, in the present embodiment, the mobile communication system 2 is described as having three base station devices 21, but this is not limiting. The mobile communication system 2 can have any number of base station devices 21. In this case, the configuration and operation of each base station device 21 are the same as those of base station device 21_1.

(flowchart)
Next, the operation of the mobile communication system 2 will be described with reference to FIG.
FIG. 7 is a flowchart showing an example of the operation of the mobile communication system 2.

In this embodiment, a case will be described in which the mobile terminal E1 is present in cell C1, which is within the wireless communication range of the base station device 21_1.

First, the mobile terminal E1 reports (transmits) the measurement result of the communication quality to the base station device 21_1 when a change in the communication quality is triggered (step S201). In the case of LTE, the mobile terminal E1 transmits a Measurement Report message to the base station device 21_1 when an event condition specified by the base station device 21_1 is triggered.

When the base station device 21_1 receives the wireless quality measurement results from the mobile terminal E1, it acquires the cell stay history of the mobile terminal E1 (step S202).

The method of acquiring the cell stay history has already been explained. Specifically, base station device 21_1 transmits a request to transmit the cell stay history of mobile terminal E1 to management device 22 via network 24. When management device 22 receives the request to transmit the cell stay history from base station device 21_1, it reads out the cell stay history of mobile terminal E1 from storage device 23 and transmits it to base station device 21_1 that made the transmission request via network 24. This allows base station device 21_1 to acquire the cell stay history of mobile terminal E1. Note that if the functionality of management device 22 is provided in base station device 21_1, acquisition of the cell stay history by base station device 21_1 is performed within its own device.

Base station device 21_1 determines from the acquired cell visit history whether mobile terminal E1 has visited cell C1 more than N times (N is an integer equal to or greater than 2) during a given period T2 (step S203).

For example, if the number of cell stays of mobile terminal E1 per predetermined period T2 is less than N (NO in step S203), base station device 21_1 selects a handover destination cell by normal processing (step S205). That is, base station device 21_1 selects the cell with the highest communication quality from among multiple cells as the handover destination cell regardless of the cell radius. Thereafter, base station device 21_1 instructs mobile terminal E1 to make the selected cell the handover destination (step S206).

On the other hand, if the number of cell stays of the mobile terminal E1 per predetermined period T2 is N or more (YES in step S203), the base station device 21_1 selects a handover destination cell by a process different from the above-mentioned normal process (step S204). Specifically, the base station device 21_1 selects a cell with a larger cell radius than the cell C1 as the handover destination cell from among multiple cells with high communication quality (step S204). In the example of FIG. 5, the base station device 21_1 selects cell C3, which has a larger cell radius than the cell C1 (and has the largest cell radius among cells C2 and C3), as the handover destination cell. Thereafter, the base station device 21_1 instructs the mobile terminal E1 to make the selected cell the handover destination (step S206).

Figure 8 is a diagram showing an example of the cell stay history of mobile terminal E1. Referring to the cell stay history in Figure 8, mobile terminal E1 first stays in cell C1 for 5 seconds, then stays in cell C2 for 5 seconds, then stays in cell C1 for 5 rows, then stays in cell C2 for 5 seconds, and then stays in cell C1 for 5 seconds. If the predetermined period T2 is set to 100 seconds and the predetermined number of times N is set to 3, the number of times that mobile terminal E1 stays in cell C1 per predetermined period T2 will be 3 or more. Therefore, base station device 21_1 instructs mobile terminal E1 to select a cell with a larger cell radius than cell C1 as the handover destination among multiple cells that are handover destination candidates. More preferably, base station device 21_1 instructs mobile terminal E1 to select a cell with the largest cell radius among multiple cells that are handover destination candidates as the handover destination.

When mobile terminal E1 receives an instruction from base station device 21_1 to select a cell with a larger cell radius as the handover destination, it switches the communication target to a base station device whose communication range is a cell with a larger cell radius than cell C1 in accordance with the instruction. More preferably, mobile terminal E1 switches the communication target to a base station device whose communication range is the cell with the largest cell radius among multiple candidate handover destination cells.

In this manner, in the mobile communication system 2 according to the present embodiment, the base station device 21_1 determines whether the number of cell stays of the mobile terminal E1 per predetermined period T2 is equal to or greater than a predetermined number of times, based on the cell stay history of the mobile terminal E1. Then, when the base station device 21_1 determines that the number of cell stays of the mobile terminal E1 per predetermined period T2 is equal to or greater than the predetermined number of times, it instructs the mobile terminal E1 to set a cell with a larger cell radius than the cell C1 as the handover destination. This allows the mobile terminal E1 to reduce the frequency of handover processing, thereby reducing power consumption without updating functions.

The functions of base station device 11 and base station device 21 may be used in combination. That is, the functions of determination unit 112 and determination unit 212 may be used in combination. The functions of instruction unit 113 and instruction unit 213 may be used in combination.

The embodiments of the present disclosure have been described in detail above with reference to the drawings, but the specific configuration is not limited to the above, and various design changes are possible without departing from the spirit of the present disclosure.

Note that in this disclosure, the communication processing by base station device 11 and base station device 21 described as hardware processing can be realized, for example, by having a CPU execute a computer program.

The above-mentioned program can be stored and supplied to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Non-transitory computer readable media include, for example, magnetic recording media, magneto-optical recording media, CD-ROM (Read Only Memory), CD-R, CD-R/W, and semiconductor memory. Magnetic recording media include, for example, flexible disks, magnetic tapes, and hard disk drives. Magneto-optical recording media include, for example, magneto-optical disks. Semiconductor memories include, for example, mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory). The program may also be supplied to a computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can provide the program to the computer via a wired communication path, such as an electric wire or optical fiber, or via a wireless communication path.

A part or all of the above embodiments may be described as follows, but is not limited to the following:

(Appendix 1)
an acquisition unit that acquires a cell stay history of a mobile terminal that is present in a first cell that is a wireless communication range of the mobile terminal itself, the cell stay history including a stay time of the first cell;
a determination unit that determines whether or not the mobile terminal has stayed in the first cell for more than a first predetermined period based on the cell stay history of the mobile terminal acquired by the acquisition unit;
an instruction unit that instructs the mobile terminal to switch a frequency of measurement of communication quality of each of the first cell and an adjacent cell from a first frequency to a second frequency that is lower than the first frequency, when it is determined that the mobile terminal has stayed in the first cell for more than a first predetermined period;
A base station device comprising:

(Appendix 2)
The instruction unit instructs the mobile terminal to stop measuring the communication quality of each of the first cell and the adjacent cells.
2. A base station apparatus as described in claim 1.

(Appendix 3)
The instruction unit instructs the mobile terminal to gradually reduce a frequency of measurement of communication quality of each of the first cell and the adjacent cell from the first frequency to the second frequency.
2. A base station apparatus as described in claim 1.

(Appendix 4)
The determination unit further determines whether or not a number of times the mobile terminal has stayed in the first cell per second predetermined period is equal to or greater than a predetermined number of times based on a cell stay history of the mobile terminal;
When it is determined that the number of times the mobile terminal stays in the first cell per the second predetermined period is equal to or greater than the predetermined number of times, the instruction unit further instructs the mobile terminal to switch a communication target to another base station device having a communication range including another cell having a larger cell radius than the first cell.
4. A base station device according to claim 1 .

(Appendix 5)
A mobile terminal;
A plurality of base station devices according to any one of Supplementary Notes 1 to 4;
A management device for managing a cell stay history of the mobile terminal;
A mobile communication system comprising:

(Appendix 6)
an acquisition unit that acquires a cell stay history of a mobile terminal that is present in a first cell that is a wireless communication range of the mobile terminal itself, the cell stay history including a stay time of the first cell;
a determination unit that determines whether or not the number of visits of the mobile terminal to the first cell per second predetermined period is equal to or greater than a predetermined number of times based on the cell visit history of the mobile terminal acquired by the acquisition unit;
an instruction unit that instructs the mobile terminal to switch a communication target to another base station device having a communication range including another cell having a larger cell radius than the first cell when it is determined that the number of times the mobile terminal stays in the first cell per the second predetermined period is equal to or greater than the predetermined number of times;
A base station device comprising:

(Appendix 7)
A mobile terminal;
A plurality of base station devices according to Supplementary Note 6;
A management device for managing a cell stay history of the mobile terminal;
A mobile communication system comprising:

(Appendix 8)
acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of the base station device, the cell stay history including a stay time of the first cell;
determining whether the mobile terminal has stayed in the first cell for more than a first predetermined period based on the acquired cell stay history of the mobile terminal;
instructing the mobile terminal to switch a frequency of measurement of communication quality of each of the first cell and adjacent cells from a first frequency to a second frequency lower than the first frequency when it is determined that the mobile terminal has been present in the first cell for more than a first predetermined period of time;
A communication method comprising:

(Appendix 9)
acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of the base station device, the cell stay history including a stay time of the first cell;
determining whether or not the number of visits of the mobile terminal to the first cell per second predetermined period is equal to or greater than a predetermined number of times based on the acquired cell visit history of the mobile terminal;
when it is determined that the number of times that the mobile terminal stays in the first cell during the second predetermined period is equal to or greater than the predetermined number of times, instructing the mobile terminal to switch a communication target to another base station device having a communication range of another cell having a larger cell radius than the first cell;
A communication method comprising:

(Appendix 10)
A process of acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of a base station device, the cell stay history including a stay time of the first cell;
A process of determining whether or not the mobile terminal has stayed in the first cell for more than a first predetermined period of time based on the acquired cell stay history of the mobile terminal;
a process of instructing the mobile terminal to switch a frequency of measurement of communication quality of each of the first cell and adjacent cells from a first frequency to a second frequency lower than the first frequency when it is determined that the mobile terminal has been present in the first cell for more than a first predetermined period of time;
A communications program that causes a computer to execute the above.

(Appendix 11)
A process of acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of a base station device, the cell stay history including a stay time of the first cell;
A process of determining whether or not the number of visits of the mobile terminal to the first cell per second predetermined period is equal to or greater than a predetermined number of times based on the acquired cell visit history of the mobile terminal;
a process of instructing the mobile terminal to switch a communication target to another base station device having a communication range including another cell having a larger cell radius than the first cell when it is determined that the number of times the mobile terminal stays in the first cell during the second predetermined period is equal to or greater than the predetermined number of times;
A communications program that causes a computer to execute the above.

REFERENCE SIGNS LIST 1 Mobile communication system 2 Mobile communication system 11 Base station device 11_1 Base station device 11_2 Base station device 12 Management device 13 Storage device 14 Network 21 Base station device 21_1 Base station device 21_2 Base station device 21_3 Base station device 22 Management device 23 Storage device 24 Network 111 Acquisition unit 112 Determination unit 113 Instruction unit 211 Acquisition unit 212 Determination unit 213 Instruction unit C1 Cell C2 Cell C3 Cell E1 Mobile terminal

Claims (6)

an acquisition unit that acquires a cell stay history of a mobile terminal that is present in a first cell that is a wireless communication range of the mobile terminal itself, the cell stay history including a stay time of the first cell;
a determination unit that determines whether or not the mobile terminal has stayed in the first cell for more than a first predetermined period based on the cell stay history of the mobile terminal acquired by the acquisition unit;
an instruction unit that instructs the mobile terminal to switch a frequency of measurement of communication quality of each of the first cell and an adjacent cell from a first frequency to a second frequency that is lower than the first frequency, when it is determined that the mobile terminal has stayed in the first cell for more than a first predetermined period;
Equipped with
The determination unit further determines whether or not a number of times the mobile terminal has stayed in the first cell per second predetermined period is equal to or greater than a predetermined number of times based on a cell stay history of the mobile terminal;
When it is determined that the number of times the mobile terminal stays in the first cell per the second predetermined period is equal to or greater than the predetermined number of times, the instruction unit further instructs the mobile terminal to switch a communication target to another base station device having a communication range including another cell having a larger cell radius than the first cell.
Base station equipment. The instruction unit instructs the mobile terminal to stop measuring the communication quality of each of the first cell and the adjacent cells.
The base station device according to claim 1 . The instruction unit instructs the mobile terminal to gradually reduce a frequency of measurement of communication quality of each of the first cell and the adjacent cell from the first frequency to the second frequency.
The base station device according to claim 1 . A mobile terminal;
A plurality of base station devices according to any one of claims 1 to 3 ;
A management device for managing a cell stay history of the mobile terminal;
A mobile communication system comprising: acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of the base station device, the cell stay history including a stay time of the first cell;
determining whether the mobile terminal has stayed in the first cell for more than a first predetermined period based on the acquired cell stay history of the mobile terminal;
instructing the mobile terminal to switch a frequency of measurement of communication quality of each of the first cell and adjacent cells from a first frequency to a second frequency lower than the first frequency when it is determined that the mobile terminal has been present in the first cell for more than a first predetermined period of time;
A communication method comprising:
In the step of determining, it is further determined whether or not the number of times that the mobile terminal has stayed in the first cell per second predetermined period is equal to or greater than a predetermined number of times based on a cell stay history of the mobile terminal;
In the instructing step, when it is determined that the number of times that the mobile terminal stays in the first cell during the second predetermined period is equal to or greater than the predetermined number of times, the instructing step further instructs the mobile terminal to switch a communication target to another base station device having a communication range including another cell having a larger cell radius than the first cell.
Communication method. A process of acquiring a cell stay history of a mobile terminal present in a first cell that is a wireless communication range of a base station device, the cell stay history including a stay time of the first cell;
A process of determining whether or not the mobile terminal has stayed in the first cell for more than a first predetermined period of time based on the acquired cell stay history of the mobile terminal;
a process of instructing the mobile terminal to switch a frequency of measurement of communication quality of each of the first cell and adjacent cells from a first frequency to a second frequency lower than the first frequency when it is determined that the mobile terminal has been present in the first cell for more than a first predetermined period of time;
A communication program for causing a computer to execute the following:
In the process of determining, it is further determined whether or not the number of visits of the mobile terminal to the first cell per second predetermined period is equal to or greater than a predetermined number of times based on a cell visit history of the mobile terminal;
In the instructing process, when it is determined that the number of times that the mobile terminal stays in the first cell during the second predetermined period is equal to or greater than the predetermined number of times, the instructing process further instructs the mobile terminal to switch a communication target to another base station device having a communication range of another cell having a larger cell radius than the first cell.
Communications program.

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