Communication device, communication method, and program

Abstract

A communication device according to one aspect of the present disclosure is a communication device that can be connected to a plurality of mobile networks via a plurality of communication modules, the communication device including a setting unit that sets, for each of the plurality of communication modules, a frequency band used by the communication module so as to reduce overlap with a frequency band used by another communication module, an allocating unit that transmits a packet of communication data from a communication application to the mobile network via a communication module of which usage is not stopped among the plurality of communication modules, a first instruction unit that instructs the communication module to stop usage or resume usage of the frequency band, in accordance with a value of a predetermined quality index relating to quality of each frequency band used by the plurality of communication modules, and a second instruction unit for instructing the allocating unit to stop usage or resume usage of the communication module in accordance with the value of the quality index of each frequency band in a cell to which the communication module is connected and the value of the quality index of each frequency band in a cell in the vicinity of the cell.

Description

Communication device, communication method, and program

[0001] The present disclosure relates to a communication device, a communication method, and a program.

[0002] Communication devices that can connect to multiple mobile networks have been known for some time. For example, Non-Patent Documents 1 and 2 disclose a method for enabling a communication device to connect to multiple mobile networks by using multiple SIM (Subscriber Identity Module) cards. For example, Non-Patent Document 3 discloses a method for enabling a communication device to connect to multiple mobile networks by storing multiple subscriber information items on a single SIM card.

[0003] Furthermore, methods for mitigating degradation of line quality due to handover (HO) in communication devices connected to mobile networks have been known for some time. For example, Non-Patent Document 4 discloses a method for controlling the timing of HO and the cell to which the handover is to be performed in an environment where two mobile networks, 4G / LTE and 5G, are available, in order to mitigate the effects of delay and reduced throughput due to HO. For example, Non-Patent Document 5 discloses a method for selecting a base station to which the handover is to be performed using a signal-to-noise ratio (SINR) as a quality indicator in a dual connectivity environment of 4G and 5G millimeter waves.

[0004] "What is Dual SIM? An explanation of its types and advantages and disadvantages," Internet <URL: https: / / media.mobile.rakuten.co.jp / contents / articles / 2020 / 00014 / > "Dual SIM," Internet <URL: https: / / ja.wikipedia.org / wiki / Dual_SIM> "IIJ Develops Multi-Profile SIM That Enables Connection to Multiple Mobile Phone Networks with a Single SIM," Internet <URL: https: / / www.iij.ad.jp / news / pressrelease / 2022 / 1025.html> T. Mumtaz, S. Muhammad, M. I. Aslam, and N. Mohammad, "Dual Connectivity-Based Mobility Management and Data Split Mechanism in 4G / 5G Cellular Networks," IEEE Access, vol. 8, pp. 86495-86509, 2020. M. Polese, M. Giordani, M. Mezzavilla, S. Rangan, and M. Zorzi, "Improved Handover Through Dual Connectivity in 5G mmWave Mobile Networks," IEEE J. Sel. Areas Commun., vol. 35, no. 9, pp. 2069-2084, Sep. 2017.

[0005] However, while the conventional techniques described in, for example, Non-Patent Documents 1, 2, and 3 allow the use of multiple mobile networks, they do not take into consideration the frequency bands used for each line, and there is a possibility that line quality may be impaired due to, for example, overlapping handovers, etc. In contrast, the conventional methods described in Non-Patent Documents 4 and 5 can mitigate the degradation of line quality due to handovers, but these conventional methods require the addition of functions to base stations, which incurs costs.

[0006] The present disclosure has been made in consideration of the above points, and aims to prevent degradation of line quality in a communication device connectable to multiple mobile networks at low cost.

[0007] A communication device according to one aspect of the present disclosure is a communication device that can connect to multiple mobile networks via multiple communication modules, and includes: a setting unit that sets the frequency band to be used by each of the multiple communication modules so as to minimize overlap with the frequency bands used by other communication modules; a distribution unit that transmits packets of communication data from a communication application to the mobile network via a communication module among the multiple communication modules that is not currently in use; a first instruction unit that instructs the communication module to suspend or resume use of the frequency band depending on the value of a predetermined quality indicator related to the quality of each frequency band used by the multiple communication modules; and a second instruction unit that instructs the distribution unit to suspend or resume use of the communication module depending on the value of the quality indicator for each frequency band in a cell to which the communication module is connected and the value of the quality indicator for each frequency band in a cell neighboring the cell.

[0008] It is possible to prevent degradation of line quality in a communication device that can connect to multiple mobile networks at low cost.

[0009] FIG. 1 is a diagram illustrating an example of a hardware configuration of a communication device according to an embodiment; FIG. 2 is a diagram illustrating an example of a functional configuration of a communication device according to an embodiment; FIG. 3 is a sequence diagram illustrating an example of an initial setting process according to an embodiment; and FIG. 4 is a sequence diagram illustrating an example of a communication process according to an embodiment.

[0010] An embodiment of the present invention will be described below. In the following embodiment, a communication device 10 will be described that can connect to multiple mobile networks via multiple communication modules and can prevent degradation of line quality at low cost. Hereinafter, it is assumed that the communication device 10 is carried by or mounted on some kind of mobile object. For example, it is assumed that the communication device 10 is carried by a person, attached to an animal, or mounted on a vehicle or aircraft (including a drone, etc.). In other words, it is assumed that the communication device 10 moves along with the movement of the mobile object carrying or mounting the communication device 10.

[0011] The communication device 10 according to this embodiment prevents degradation of line quality when connecting to multiple mobile networks by combining three techniques: "control before starting communication," "control of frequency bands used during communication," and "packet scheduling during communication." An outline of each of these three techniques will be explained below.

[0012] Control before communication starts Before communication starts, it is not possible to measure the communication quality of each frequency band available on each line. Therefore, before communication starts, the frequency band to be used by each communication module is set from among the frequency bands available to that communication module, in a combination that is different from that of other communication modules, and in which overlapping of frequency bands between communication modules is minimized. This prevents overlapping use of the same frequency band between communication modules as much as possible, and suppresses simultaneous occurrence of HO (handover).

[0013] Frequency band usage control during communication: The quality index value representing the line quality in each frequency band is measured, and the use of a frequency band where the quality index value falls below a predetermined threshold is stopped. Furthermore, after the use of a certain frequency band is stopped, if the quality index value rises above the threshold due to the occurrence of a handover or a change in the position of the communication device 10, the use of that frequency band is resumed. Note that, as the quality index value, for example, an IP layer quality index value such as RTT (Round-Trip Time), or a wireless layer quality index value such as RSSI (Received Signal Strength Indicator) or RSRP (Reference Signal Received Power) can be used. This prevents the use of frequency bands with poor quality index values, thereby improving line quality.

[0014] Packet schedule during communication: The quality index value of each frequency band is monitored, and if the quality index value of the wireless layer of the cell to which the communication module is connected has recently deteriorated and there is a nearby cell with a better wireless layer quality index value than the cell to which the communication module is connected, packet transmission from that communication module is stopped. Also, after packet transmission from a certain communication module is stopped, if HO of that communication module is completed or the quality index value of the wireless layer recovers, packet transmission from that communication module is resumed. This prevents packet transmission from a communication module that is likely to cause HO, and makes it possible to prevent a deterioration in line quality due to HO.

[0015] By combining the above three methods, it becomes possible to improve line quality not for each communication module, but for the entire communication device 10 that connects to multiple mobile networks via multiple communication modules. Furthermore, since all of the above three methods can be executed by the communication device 10 alone, there is no need to modify the base station, for example, by adding functions to the base station, and it becomes possible to improve line quality at low cost.

[0016] <Example of Hardware Configuration of Communication Device 10> An example of the hardware configuration of the communication device 10 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the hardware configuration of the communication device 10 according to this embodiment.

[0017] 1, a communication device 10 according to this embodiment includes an input / output device 11, an external I / F 12, a plurality of communication I / Fs 13, a memory device 14, and a processor 15. Each of these pieces of hardware is connected to each other via a bus 16 so as to be able to communicate with each other.

[0018] The input / output device 11 is, for example, a touch panel, physical buttons, a display panel, etc. Note that the communication device 10 does not necessarily have to include the input / output device 11, for example.

[0019] The external I / F 12 is an interface with an external device such as a recording medium 12a, etc. Examples of the recording medium 12a include a Secure Digital memory card (SD memory card) and a Universal Serial Bus (USB) memory card.

[0020] Each communication I / F 13 is an interface for connecting to each communication module 20. Here, the communication module 20 is a device for connecting to a mobile network, and is connected to a base station of the mobile network and connected to an external network via the base station. Each communication module 20 is assumed to hold information indicating frequency bands available for that communication module 20. Furthermore, at least one communication device 10 among the communication modules 20 is assumed to be capable of measuring quality index values ​​in each frequency band of the cell to which that communication module 20 is currently connected and its neighboring cells. Hereinafter, when distinguishing between each of the multiple communication modules 20, they will be referred to as "communication module 20-n" (n = 1, ..., N), where N is the total number of communication modules 20. Furthermore, the communication I / F 13 for connecting to the communication module 20-n will be referred to as "communication I / F 13-n."

[0021] The memory device 14 is a storage device that stores programs and data. Examples of the memory device 14 include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), and a flash memory.

[0022] The processor 15 is a computing device that executes the programs stored in the memory device 14. Examples of the processor 15 include a central processing unit (CPU), a micro processing unit (MPU), and a field programmable gate array (FPGA).

[0023] 1 is an example, and the hardware configuration of the communication device 10 is not limited thereto. For example, the communication device 10 may have multiple memory devices 14 or multiple processors 15, or may have various hardware components other than the hardware illustrated. For example, the communication device 10 may have a positioning module that receives a GPS (Global Positioning System) signal to determine its location.

[0024] In addition, in the example shown in FIG. 1, the communication module 20 is connected to the communication device 10 via the communication I / F 13, but for example, all or part of the communication module 20 may be included in the communication device 10.

[0025] <Example of Functional Configuration of Communication Apparatus 10> An example of the functional configuration of the communication apparatus 10 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the functional configuration of the communication apparatus 10 according to this embodiment.

[0026] 2, the communication device 10 according to this embodiment includes one or more communication applications 101, a distribution unit 102, a connection setting instruction unit 103, a communication module information collection unit 104, and a communication module information storage unit 105. Each communication application 101 is realized, for example, by a program executed by the processor 15. The distribution unit 102, the connection setting instruction unit 103, and the communication module information collection unit 104 are realized, for example, by processing executed by the processor 15 or the like by one or more programs stored in the memory device 14. The communication module information storage unit 105 is realized, for example, by a storage area of ​​the memory device 14.

[0027] The communication application 101 generates communication data to be transmitted to an external network via the communication module 20. The communication application 101 also transmits the generated communication data to the distribution unit 102.

[0028] The allocating unit 102 selects a communication module 20 to be used for packet transmission of communication data transmitted from the communication application 101 from among the communication modules 20 that can be used for packet transmission. The allocating unit 102 also transmits the packet of communication data to the selected communication module 20 via the communication I / F 13 corresponding to the selected communication module 20.

[0029] Before starting communication, the connection setting instruction unit 103 sets a combination of frequency bands to be used by each communication module 20. Furthermore, the connection setting instruction unit 103 evaluates a quality index value during communication, and instructs each communication module 20 to stop or resume use of the frequency bands used by the communication module 20, or instructs each communication module 20 to stop or resume use.

[0030] Before starting communication, the communication module information collection unit 104 collects information indicating the frequency bands available for use by each communication module 20. The communication module information collection unit 104 also stores in the communication module information storage unit 105 the number of communication modules 20 connected to the communication device 10 and information indicating the frequency bands available for use by each of the communication modules 20.

[0031] The communication module information storage unit 105 stores information indicating the number of communication modules 20 connected to the communication device 10 and the frequency bands available for each of the communication modules 20 .

[0032] <Details of the processing performed by the communication device 10> Below, the details of the processing performed by the communication device 10 according to this embodiment will be explained, dividing it into an initial setting processing performed before the communication application 101 starts communication and a communication processing performed during communication of the communication application 101.

[0033] <<Initial Setting Process>> An example of the initial setting process according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a sequence diagram showing an example of the initial setting process according to this embodiment.

[0034] First, the communication module information collection unit 104 collects information indicating frequency bands available for use by each communication module 20 (step S101). Note that the communication module information collection unit 104 can collect information indicating frequency bands available for use by each communication module 20 by using, for example, mmcli, which is a command line tool for controlling LTE modules in Linux (registered trademark), AT commands used for collecting information on and controlling communication modules, or the like.

[0035] Next, the communication module information collection unit 104 stores information indicating the number of communication modules 20 connected to the communication device 10 and the frequency bands available for use by each of those communication modules 20 (hereinafter also referred to as available frequency bands) in the communication module information storage unit 105 (step S102).

[0036] Next, the communication module information collection unit 104 notifies the connection setting instruction unit 103 of the available frequency bands of each communication module 20 (step S103).

[0037] Next, when the connection setting instruction unit 103 is notified of the available frequency bands of each communication module 20, it determines the frequency bands to be used by each communication module 20 (hereinafter also referred to as the used frequency bands) (step S104). At this time, the connection setting instruction unit 103 determines, as the used frequency bands, frequency bands that are different from the combinations of frequency bands used by other communication modules 20 and that minimize overlap of the used frequency bands between each communication module 20. In other words, the connection setting instruction unit 103 determines, as the used frequency bands, a combination of one or more frequency bands from the available frequency bands of communication module 20-n (n=1, ..., N). ｎ In this case, the connection setting instruction unit 103 selects, for example, a combination C that satisfies all of the following conditions 1 to 3: ｎ The frequency bands constituting the above are determined as the frequency bands to be used by the communication module 20-n.

[0038] Condition 1: For any n, n'∈[1,...,N] where n≠n', C ｎ ≠C ｎ' is.

[0039] Condition 2: For any n, n'∈[1,...,N] where n≠n', C ｎ and C ｎ' The number of frequency bands included in both ｎｎ' When this is done, K ｎｎ' C such that the sum of (n, n') of ｎ is.

[0040] Condition 3: For any n∈[1,...,N], C ｎ C that makes the number of frequency bands that make up the largest (or is equal to or greater than a predetermined threshold) ｎ is.

[0041] As a specific example, assume that there are two communication modules 20, communication module 20-1 and communication module 20-2. Also, assume that the available frequency bands of communication module 20-1 and communication module 20-2 are "band 1 (2.1 GHz)," "band 42 (3.5 GHz)," and "band 28 (700 MHz)." In this case, the connection setting instruction unit 103 may determine, for example, the available frequency bands of communication module 20-1 to be "band 1 (2.1 GHz)" and "band 28 (700 MHz)," and the available frequency bands of communication module 20-2 to be "band 42 (3.5 GHz)" and "band 28 (700 MHz)."

[0042] Then, the connection setting instruction unit 103 sets the utilization frequency bands of each communication module 20 to each communication module 20 (step S105). For example, in the above specific example, the connection setting instruction unit 103 sets the utilization frequency bands "band 1 (2.1 GHz)" and "band 28 (700 MHz)" for the communication module 20-1, and sets the utilization frequency bands "band 42 (3.5 GHz)" and "band 28 (700 MHz)" for the communication module 20-2. As a result, the utilization frequency bands to be used by each communication module 20 are set for that communication module 20. At this time, since the utilization frequency bands of each communication module 20 are determined by the method described in step S104 above, overlapping use of the same frequency band between the communication modules 20 is prevented as much as possible. This makes it possible to prevent simultaneous handovers between the communication modules 20. Note that information indicating the utilization frequency bands set for each communication module 20 is stored in, for example, the memory device 14.

[0043] <Communication Processing> An example of communication processing according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a sequence diagram showing an example of communication processing according to this embodiment. Note that the communication processing shown in Fig. 4 is repeatedly executed during communication by the communication application 101.

[0044] First, each communication module 20 notifies the connection setting instruction unit 103 of a cell ID, which is the ID of the cell to which the communication module 20 is connected (more precisely, the base station of that cell), and the quality index values ​​of each frequency band in the cell of that cell ID and its neighboring cells (step S201). Note that the cell ID is notified to the connection setting instruction unit 103, for example, from all communication modules 20. On the other hand, the quality index values ​​of each frequency band are notified to the connection setting instruction unit 103, for example, from one specific communication module 20. For example, if one communication module 20 among the communication modules 20-n (n = 1, ..., N) is capable of both measuring quality index values ​​and transmitting packets (U-plane communication), the quality index values ​​of each frequency band are notified to the connection setting instruction unit 103 from that communication module 20. Alternatively, for example, if a communication module dedicated to measuring quality index values ​​exists separately from the communication module 20-n (n = 1, ..., N), the quality index value of each frequency band may be notified from the communication module dedicated to measurement to the connection setting instruction unit 103. However, this is just one example, and for example, two or more communication modules 20 may notify the connection setting instruction unit 103 of the quality index value of each frequency band.

[0045] Next, when the connection setting instruction unit 103 is notified of the quality index value of each frequency band, the connection setting instruction unit 103 evaluates the quality index value (step S202). At this time, the connection setting instruction unit 103 performs the following two evaluations: "used frequency band evaluation" and "HO evaluation".

[0046] Frequency Band Evaluation: When the quality index value of a frequency band falls below a predetermined threshold, the connection setting instruction unit 103 evaluates that the use of the frequency band should be stopped. Furthermore, when the quality index value of a frequency band whose use is currently suspended becomes equal to or greater than the threshold, the connection setting instruction unit 103 evaluates that the use of the frequency band should be resumed. The threshold is set in advance depending on the type of frequency band, quality index value, etc.

[0047] HO Evaluation When the quality index value of the wireless layer of a cell to which a certain communication module 20 is connected deteriorates and there is a nearby cell with a better wireless layer quality index value than the cell to which that communication module 20 is connected, the connection setting instruction unit 103 evaluates that there is a possibility that HO will occur in that communication module 20. Note that when the quality index value of the wireless layer of a cell deteriorates, this means, for example, when the quality index value of the wireless layer of that cell has dropped by a certain amount or more compared to the previous wireless layer quality index value of that cell.

[0048] In addition, the connection setting instruction unit 103 evaluates that the quality of a communication module 20 that is currently out of use has recovered if the quality index value of the wireless layer of the cell to which the communication module is connected becomes equal to or greater than a predetermined threshold value.

[0049] Furthermore, if the cell to which a communication module 20 that is currently out of service is connected has changed (i.e., if the cell ID has changed since the previous time), the connection setting instruction unit 103 evaluates that HO has been completed.

[0050] If it is evaluated that the use of a frequency band should be stopped or resumed, the connection setting instruction unit 103 instructs the communication module 20 that has set that frequency band to stop or resume use (step S203). That is, if it is evaluated that the use of a certain frequency band should be stopped, the connection setting instruction unit 103 instructs the communication module 20 that has set that frequency band to stop use of that frequency band. However, if, as a result of this instruction to stop use, the number of frequency bands that are not currently being stopped in that communication module 20 becomes zero, the connection setting instruction unit 103 instructs the communication module 20 to resume use of, for example, the frequency band that has the largest quality index value, such as RSRP, among the frequency bands used by that communication module 20. On the other hand, if it is evaluated that the use of a certain frequency band that has been stopped should be resumed, the connection setting instruction unit 103 instructs the communication module 20 that has set that frequency band to resume use of that frequency band. This allows the use of the available frequency band to be stopped or resumed, preventing the use of a frequency band with a poor quality index value, and allowing the frequency band to be used again if the quality index value recovers.

[0051] If it is evaluated that there is a possibility that HO will occur, that the quality has recovered, or that HO has been completed, the connection setting instruction unit 103 instructs the allocation unit 102 to suspend or resume use of the corresponding communication module 20 (step S204). That is, if it is evaluated that there is a possibility that HO will occur in a certain communication module 20, the connection setting instruction unit 103 instructs the allocation unit 102 to suspend use of that communication module 20. However, if the number of communication modules 20 that are not suspended becomes zero as a result of this suspension instruction, the connection setting instruction unit 103 instructs the allocation unit 102 to resume use of the communication module 20 that has set, as the frequency band to be used, the frequency band with the largest quality index value, such as RSRP. On the other hand, if it is evaluated that the quality of a certain communication module 20 that has been suspended, has recovered, the connection setting instruction unit 103 instructs the allocation unit 102 to resume use of that communication module 20. Similarly, when it is evaluated that HO of a certain communication module 20 that is currently out of use has been completed, the connection setting instruction unit 103 instructs the allocation unit 102 to resume use of that communication module 20. This prevents packet transmission from a communication module 20 that may cause HO, and also makes it possible to use that communication module 20 again when HO is completed or when the quality of the wireless layer is restored without HO being performed.

[0052] The communication application 101 generates communication data and transmits it to the distribution unit 102 (step S205).

[0053] When the allocating unit 102 receives communication data from the communication application 101, it selects a communication module 20 that transmits a packet of the communication data from among the communication modules 20 that are not suspended (step S206). The allocating unit 102 may select a communication module 20 that transmits a packet of the communication data from among the communication modules 20 that are not suspended using any method. For example, the allocating unit 102 may select a communication module 20 that transmits a packet from among the communication modules 20 that are not suspended using a round robin method. However, this is just one example, and it is also possible to randomly select a communication module 20 that transmits a packet from among the communication modules 20 that are not suspended, or to select a communication module 20 that has a good index value (for example, a quality index value of a wireless layer, etc.).

[0054] Then, the distribution unit 102 transmits the communication data packet to the selected communication module 20 via the communication I / F 13 corresponding to the selected communication module 20 (step S207). As a result, the communication data packet is transmitted to the external network.

[0055] <Modification> A modification of the above embodiment will be described below. In this modification, the communication device 10 has a positioning module capable of measuring the current position, and executes the following measurement phase and utilization phase.

[0056] Measurement Phase In the measurement phase, the communication device 10 mounted on a mobile object, for example, uses a communication module dedicated to measurement to generate quality information including time, availability of each frequency band, a quality index value for each frequency band, and whether or not handover has occurred. At the same time, the communication device 10 uses a positioning module, for example, to generate location information including time and location (latitude and longitude). Then, data (hereinafter referred to as pre-measurement data) is generated by combining the quality information and location information by time. This pre-measurement data is stored, for example, in a memory device 14.

[0057] Usage Phase In the usage phase, a communication device 10 mounted on a mobile object, for example, uses a positioning module to determine its current location and predicts its location at a predetermined time ΔT in the future using a known prediction method. Next, the communication device 10 determines whether the quality index value will decrease at the predicted location using quality information corresponding to the current location and quality information corresponding to the predicted location. The communication device 10 then uses this determination result when evaluating the quality index value in step S202 above. As a result, for example, if the quality index value of a certain frequency band used at the predicted location decreases, the use of that frequency band can be stopped. Similarly, if the quality index value of a certain frequency band that has been suspended recovers at the predicted location, the use of that frequency band can be resumed.

[0058] <Summary> As described above, the communication device 10 according to the present embodiment combines three techniques, namely, "control before starting communication," "control of frequency bands used during communication," and "packet scheduling during communication," to enable the communication device 10 as a whole to improve line quality when connected to multiple mobile networks. Moreover, because the communication device 10 according to the present embodiment executes these three techniques as internal processing, there is no need to modify the base station, for example, by adding functions to the base station, and line quality can be improved at low cost.

[0059] The present invention is not limited to the above-described specifically disclosed embodiments, and various modifications, changes, and combinations with known technologies are possible without departing from the scope of the claims.

[0060] REFERENCE SIGNS LIST 10 Communication device 11 Input / output device 12 External I / F 12a Recording medium 13 Communication I / F 14 Memory device 15 Processor 16 Bus 20 Communication module 101 Communication application 102 Distribution unit 103 Connection setting instruction unit 104 Communication module information collection unit 105 Communication module information storage unit

Claims

1. A communications device connectable to multiple mobile networks via multiple communications modules, comprising: a setting unit that sets, for each of the multiple communications modules, a frequency band to be used by the communications module so as to minimize overlap with frequency bands used by other communications modules; a distribution unit that transmits packets of communications data from a communications application to the mobile network via a communications module among the multiple communications modules that is not currently in use; a first instruction unit that instructs the communications module to suspend or resume use of the frequency band depending on a predetermined quality indicator value related to the quality of each frequency band used by the multiple communications modules; and a second instruction unit that instructs the distribution unit to suspend or resume use of the communications module depending on the quality indicator value of each frequency band in a cell to which the communications module is connected and the quality indicator value of each frequency band in a cell neighboring the cell.

2. The communication device of claim 1, wherein the first instruction unit instructs a communication module using the frequency band to stop using the frequency band when the value of the quality index of the frequency band is less than a predetermined threshold, and instructs a communication module using the frequency band to resume using the frequency band when the value of the quality index of the frequency band whose use is suspended is equal to or greater than the threshold.

3. The communication device of claim 1 or 2, wherein the second instruction unit instructs the allocation unit to suspend use of the communication module when the value of the quality index for each frequency band in the cell to which the communication module is connected drops by more than a predetermined value and there is a neighboring cell having a better quality index value than the cell to which the communication module is connected, and instructs the allocation unit to resume use of the communication module when the value of the quality index for each frequency band in the cell to which the suspended communication module is connected becomes more than a predetermined threshold value or when the cell to which the communication module is connected changes.

4. The communication device according to claim 3, wherein the quality indicators include quality indicators of a wireless layer, including RSSI and RSRP.

5. The communication device according to claim 1, wherein the setting unit sets one or more frequency bands to be used by the communication module from among frequency bands available to the communication module so as to minimize overlap with frequency bands used by other communication modules.

6. A communications method in which a communications device connectable to multiple mobile networks via multiple communications modules executes the following steps: a setting step of setting, for each of the multiple communications modules, a frequency band to be used by the communications module so as to reduce overlap with frequency bands used by other communications modules; a distribution step of transmitting packets of communications data from a communications application to the mobile network via a communications module among the multiple communications modules that is not in use; a first instruction step of instructing the communications module to suspend or resume use of the frequency band depending on a predetermined quality index value related to the quality of each frequency band used by the multiple communications modules; and a second instruction step of instructing the communications module to suspend or resume use depending on a quality index value of each frequency band in a cell to which the communications module is connected and a quality index value of each frequency band in a cell neighboring the cell.

7. A program for causing a communication device connectable to multiple mobile networks via multiple communication modules to execute the following steps: a setting step for setting, for each of the multiple communication modules, a frequency band to be used by the communication module so as to reduce overlap with frequency bands used by other communication modules; a distribution step for transmitting packets of communication data from a communication application to the mobile network via a communication module among the multiple communication modules that is not currently in use; a first instruction step for instructing the communication module to suspend or resume use of the frequency band depending on a predetermined quality index value related to the quality of each frequency band used by the multiple communication modules; and a second instruction step for instructing the communication module to suspend or resume use depending on a quality index value of each frequency band in a cell to which the communication module is connected and a quality index value of each frequency band in a cell neighboring the cell.

Images