Control device, wireless communication method, wireless communication system, and control program

Abstract

A control device according to one embodiment of the present invention performs control such that a transmission capacity of each channel is calculated as an evaluation value, a total evaluation value for each combination of one or more channels having frequency bands which do not overlap with each other is calculated, a combination of a predetermined number of channels having the maximum calculated total evaluation value within a predetermined range is selected, a weighting coefficient indicating the proportion of a usage period for each of the channels included in the selected combination is calculated on the basis of a transmission rate or a transmittable data amount of each channel, a switching time to switch each of the channels included in the selected combination is calculated for each of the channels on the basis of the calculated weighting coefficient, and a traffic is transmitted by switching the channels included in the selected combination on the basis of each of the calculated switching times.

Description

Technical Field

[0001] The present invention relates to a control device, a wireless communication method, a wireless communication system, and a control program.

Background Art

[0002] In a wireless communication system using the 920 MHz band in Japan, there is a system that limits the total transmission time per unit time for each channel. For example, the total transmission time of a wireless communication terminal is limited to within 360 seconds per hour (Duty ratio 10%).

[0003] Recently, IoT (Internet of Things) terminals have become widespread and their applications have diversified. Therefore, there are also usage examples where short-time communication alone is not sufficient as in the past (such as monitoring camera video transmission in a wide area).

[0004] When there is a limit (Duty limit) on the total transmission time in this way, the amount of data that can be transmitted is limited separately from the potential of the wireless communication terminal, so there may be cases where a sufficient transmission amount cannot be ensured.

[0005] However, the above limit on the total transmission time is a limit per channel, and for each wireless communication terminal, by utilizing a plurality of channels, transmission up to a maximum of 720 seconds is possible.

[0006] At this time, the conditions for increasing the total transmission time (Duty ratio) used by one wireless transmission device are as follows.

[0007] · Use a plurality of non-overlapping channels (two or more channels) · The channels should be used "alternately" (simultaneous use is generally prohibited) · For the use of each channel, transmission time, carrier sense, and pause time are required for each channel

Prior Art Documents

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, the channels available for wireless communication are limited, and not every channel can be switched. Also, unlike conventional channel selection methods, when selecting multiple channels, it is a condition that their occupied bands do not overlap with each other.

[0010] In addition, when switching to channels with different bandwidths, the amount of data that can be transmitted before and after the switch is different, and it is also conceivable that the communication quality changes and the user's perceived quality deteriorates.

[0011] In addition, when switching and using a plurality of channels, not only does the wireless communication terminal simply mount two wireless communication modules in one housing, but time control or status control becomes necessary.

[0012] The present invention has been made in view of the above-described problems, and an object thereof is to provide a control device, a wireless communication method, a wireless communication system, and a control program capable of maximizing the transmission capacity within a predetermined range even when a limit is imposed on the total transmission time for transmitting traffic per unit time for each channel.

Means for Solving the Problems

[0013] A control device according to an embodiment of the present invention is a control device for controlling a wireless communication system that performs wireless communication using at least any one of a plurality of channels, and a limit is imposed on the total transmission time for transmitting traffic per unit time for each channel. The control device includes: an evaluation value total calculation unit that calculates the transmission capacity of each channel as an evaluation value and calculates the total evaluation value of each combination of one or more channels whose frequency bands do not overlap each other; a selection unit that selects a combination of a predetermined number of channels in which the total evaluation value calculated by the evaluation value total calculation unit is maximized within a predetermined range; a weight coefficient calculation unit that calculates a weight coefficient indicating the ratio of the usage period for each channel included in the combination selected by the selection unit based on the transmission rate or the amount of data that can be transmitted for each channel; a switching time calculation unit that calculates a switching time at which each channel included in the combination selected by the selection unit should be switched based on the weight coefficient calculated by the weight coefficient calculation unit; and a switching control unit that controls to switch the channels included in the combination selected by the selection unit and transmit traffic based on each switching time calculated by the switching time calculation unit.

[0014] Also, in a wireless communication method according to an embodiment of the present invention, in a wireless communication method that performs wireless communication using at least any one of a plurality of channels, with a limit imposed on the total transmission time for transmitting traffic per unit time for each channel, an evaluation value is calculated as the transmission capacity of each channel, and a total evaluation value is calculated for each combination of one or more channels whose frequency bands do not overlap with each other. An evaluation value total calculation step, a selection step of selecting a combination of a predetermined number of channels for which the calculated total evaluation value is maximized within a predetermined range, a weight coefficient calculation step of calculating a weight coefficient indicating the ratio of the utilization period for each channel included in the selected combination based on the transmission rate or the amount of data that can be transmitted for each channel, a switching time calculation step of calculating a switching time at which each channel included in the selected combination should be switched based on the calculated weight coefficient, and a switching control step of controlling to switch the channels included in the selected combination and transmit traffic based on each of the calculated switching times. It is characterized by including.

[0015] Also, a wireless communication system according to an embodiment of the present invention is a wireless communication system that performs wireless communication using at least any one of a plurality of channels, with a limit imposed on the total transmission time for transmitting traffic per unit time for each channel. An evaluation value total calculation unit that calculates the transmission capacity of each channel as an evaluation value and calculates the total evaluation value for each combination of one or more channels whose frequency bands do not overlap with each other, and a combination of a predetermined number of channels for which the total evaluation value calculated by the evaluation value total calculation unit is maximized within a predetermined range. A selection unit that selects, a weight coefficient calculation unit that calculates a weight coefficient indicating the ratio of the utilization period for each channel included in the combination selected by the selection unit based on the transmission rate or the amount of data that can be transmitted for each channel, and a switching time for each channel included in the combination selected by the selection unit based on the weight coefficient calculated by the weight coefficient calculation unit. A switching time calculation unit that calculates the time, and a switching control unit that controls to switch the channels included in the combination selected by the selection unit and transmit traffic based on each of the switching times calculated by the switching time calculation unit. It is characterized by having.

Advantages of the Invention

[0016] According to the present invention, even if a limit is imposed on the total transmission time for transmitting traffic per unit time for each channel, the transmission capacity can be maximized within a predetermined range.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0018] Hereinafter, a wireless communication system according to an embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a wireless communication system 1 according to an embodiment. As shown in FIG. 1, a wireless communication system 1 according to an embodiment is configured such that, for example, N terminals (wireless communication terminals: STAs) 2-1 to 2-N perform wireless communication via an access point (AP) 3. Further, the access point 3 performs wireless communication in accordance with the control of the control device 4.

[0019] Note that the wireless communication system 1 is restricted by the total sum of the transmission times for transmitting traffic per unit time for each channel. For example, under the control of the control device 4, the terminals 2-1 to 2-N and the access point 3 are configured to perform wireless communication using at least any one of a plurality of channels.

[0020] FIG. 2 is a diagram showing a configuration example of the access point 3. As shown in FIG. 2, the access point 3 is connected via a bus 37, for example, to a memory 30, a drive 31, a user interface 32, a wired communication module 33, wireless communication modules 34-1, 34-2, a timer 35, and a control circuit 36.

[0021] The memory 30 is a storage device that stores, for example, a control program 300 and management information 302. The drive 31 reads or writes data to and from a storage medium 310. The user interface 32 is an input / output device including, for example, a keyboard and a display.

[0022] The wired communication module 33 is a module that performs wired communication with other devices. The wireless communication modules 34-1, 34-2 are modules that perform wireless communication with other devices, respectively. Note that the number of wireless communication modules included in the access point 3 is not limited to two.

[0023] Timer 35 measures the time when access point 3 performs control. Control circuit 36 controls each part that constitutes access point 3. For example, control circuit 36 performs control using the time measured by timer 35.

[0024] Note that each of terminals 2-1 to 2-N and control device 4 may be configured in the same manner as access point 3 described above. Hereinafter, when not specifying any one of the configurations with a plurality such as terminals 2-1 to 2-N, it is simply abbreviated as terminal 2 or the like.

[0025] FIG. 3 is a functional block diagram illustrating the functions of control device 4. As shown in FIG. 3, control device 4 includes, for example, an evaluation value total calculation unit 50, a selection unit 52, a weight coefficient calculation unit 54, a switching time calculation unit 56, and a switching control unit 58.

[0026] The evaluation value total calculation unit 50 first acquires information such as the radio wave situation, bandwidth, RSSI (Received Signal Strength Indicator), and traffic volume used for wireless communication between terminals 2-1 to 2-N and access point 3 in the wireless communication system 1. Then, the evaluation value total calculation unit 50 calculates the transmission capacity of each channel as an evaluation value, calculates the total evaluation value of each combination of one or more channels whose frequency bands do not overlap with each other, and outputs the calculation result to the selection unit 52.

[0027] The selection unit 52 selects a combination of a predetermined number (for example, two) of channels in which the total evaluation value calculated by the evaluation value total calculation unit 50 is the maximum within a predetermined range (for example, 720 seconds), and outputs the selection result to the weight coefficient calculation unit 54 and the switching time calculation unit 56.

[0028] The weight coefficient calculation unit 54 first obtains information such as the radio wave situation, bandwidth, RSSI, and traffic volume used for wireless communication between the terminals 2-1 to 2-N and the access point 3 in the wireless communication system 1, for example. Then, based on the bandwidth, transmission rate, transmittable data volume, RSSI, etc. of each channel, the weight coefficient calculation unit 54 calculates a weight coefficient indicating the ratio of the usage period for each channel included in the combination selected by the selection unit 52, and outputs the calculated weight coefficient to the switching time calculation unit 56.

[0029] Based on the weight coefficient calculated by the weight coefficient calculation unit 54, the switching time calculation unit 56 calculates the switching time for switching each channel included in the combination selected by the selection unit 52, and outputs the calculation result to the switching control unit 58.

[0030] Based on each switching time calculated by the switching time calculation unit 56, the switching control unit 58 controls the access point 3 (or the terminal 2) to switch the channels included in the combination selected by the selection unit 52 so as to transmit traffic.

[0031] Also, the switching control unit 58 performs switching control so that the access point 3 (or the terminal 2) repeats channel switching within a monitoring time (for example, 30 minutes) predetermined to be a period shorter than the unit time (for example, 1 hour).

[0032] Note that each function of the control device 4 shown in FIG. 3 may be provided in the access point 3.

[0033] Next, an operation example of the wireless communication system 1 according to an embodiment will be described. First, with reference to FIG. 4, the parameters used in the operation example of the wireless communication system 1 will be described. As shown in FIG. 4, S window is assumed to be the Duty window size (Window time: μsec) set or specified by a vendor / manufacturer, etc.

[0034] S txIt is assumed to be the cumulative time (μsec) of the radio signal that can be transmitted within the Duty window set or specified by the vendor / manufacturer, etc.

[0035] G traffic For example, G is the total traffic that terminal 2 can transmit per unit time, and is the traffic (bps) when the Duty ratio has a maximum of 20% per terminal (the total transmission time within one hour is within 720 seconds).

[0036] G 10%traffic For example, G is the traffic (bps) that terminal 2 can transmit per unit time, and is the traffic when the Duty ratio has a maximum of 10% (the total transmission time within one hour is within 360 seconds).

[0037] D traffic For example, D is assumed to be the traffic (bps) that terminal 2 actually transmits.

[0038] Figure 5 is a flowchart showing an operation example of the wireless communication system 1 according to an embodiment.

[0039] In step 100 (S100), the wireless communication system 1 numerically evaluates the capacity of each selectable channel (transmission rate of all bandwidths) by the total evaluation value calculation unit 50 provided in the control device 4. Then, the total evaluation value calculation unit 50 calculates the total of the evaluation values of a plurality of combinable channels (here, assuming 2 channels, but not limited) on the premise that terminal 2 and access point 3 use a plurality of channels.

[0040] Note that a plurality of channels can be combined only within a range where the occupied frequency bands (frequency bands used by the channels) do not overlap with each other.

[0041] For example, in the channel example shown in FIG. 6, the channels that can be combined with a 1 MHz-wide (bandwidth) channel (1) are channels other than (2) and (4). Also, the channels that can be combined with the 2 MHz-wide (2) are channels other than (1), (3), and (4).

[0042] However, if there are no other channels that can be combined with the maximum selectable channel bandwidth, instead of the sum of the evaluation values of the combined channels, the evaluation value of one channel shall be treated in the same way as the total value.

[0043] In step 102 (S102), the selection unit 52 determines whether D traffic (the assumed transmission traffic) can be transmitted within 10% of the duty ratio of the channel with the maximum evaluation value, or whether there is a channel that can be changed. That is, the selection unit 52 determines whether D traffic ≦G 10%traffic , or whether the number of channels that can be changed = 0. If the answer is no, the process proceeds to the process of S104. If the answer is yes, the process proceeds to the process of S108. Note that the selection unit 52 determines that the channel switching is unnecessary when D traffic ≦G 10%traffic , or when the number of channels that can be changed = 0.

[0044] In step 104 (S104), the selection unit 52 selects a combination of a plurality of channels (two channels in this embodiment) whose total evaluation value is the maximum within a predetermined range (the total transmission time per hour is within 720 seconds).

[0045] In step 106 (S106), the switching control unit 58 performs switching control to switch a plurality of channels based on the switching time calculated by the switching time calculation unit 56 (see FIG. 7 described later).

[0046] In step 108 (S108), the selection unit 52 selects the channel with the maximum evaluation value.

[0047] In step 110 (S110), the switching control unit 58 executes communication using the channel selected by the selection unit 52 in the process of S108.

[0048] FIG. 7 is a flowchart showing the processing executed for the control of the control device 4 to switch a plurality of channels.

[0049] In step 200 (S200), when the traffic assumed to be transmitted exceeds a duty ratio of 10% and does not exceed a duty ratio of 20%, the control device 4 determines to start the calculation process of the switching time. Specifically, the selection unit 52 determines whether D traffic >G 10%traffic , and D traffic ≦G traffic . If No, the process proceeds to the process of S202, and if Yes, the process proceeds to the process of S204.

[0050] In step 202 (S202), the selection unit 52 performs a process of considering that D traffic =G traffic .

[0051] That is, when the traffic assumed to be transmitted by the control device 4 exceeds a duty ratio of 20%, instead of calculating to transmit all the assumed traffic, the calculation is performed with a duty ratio of 20% as the upper limit. Specifically, when D traffic >G traffic , since the traffic assumed to be transmitted is too large, the assumed traffic is replaced with the traffic that can be transmitted.

[0052] In step 204 (S204), the control device 4 starts the calculation of the switching time. At this time, the control device 4 sets, as the switching time, the time obtained by multiplying the above-described weighting factor for each channel with respect to the window (monitoring time (S window : channel usage period) for observing the duty) from the start of the window.

[0053] FIG. 8 is a diagram showing parameters regarding weight coefficients w1 and w2 when the control device 4 performs control to switch between two channels. As shown in FIG. 8, bw1 and bw2 respectively indicate the bandwidths of the channels to be switched, SINR1 and SINR2 indicate the SINR (Signal to Interference plus Noise Ratio) values at each channel of the representative terminal, and R1 and R2 indicate the transmission rates of the optimal MCS (Modulation and Coding Scheme) at each channel of the representative terminal.

[0054] Then, the weight coefficient calculation unit 54 calculates the weight coefficients w1 and w2 by the following equations (1) and (2), respectively.

[0055]

Equation

Equation

[0056] Note that the weight coefficients w1 and w2 may be calculated not only by the transmission rate ratio of the optimal MCS but also as the ratio of the data amounts that can be transmitted with a duty ratio of 10% within the Window of the transmission rate.

[0057] In step 206 (S206: FIG. 7), the switching control unit 58 starts measuring the switching times (switching fixed times: first timing 1, second timing) calculated by the switching time calculation unit 56 by the following equations (3) and (4) for each of the two channels selected by the selection unit 52, for example.

[0058]

Equation

Equation

[0059] In step 208 (S208), the control device 4 sets the upper limit (Duty ratio 10%) of the traffic for each channel of each terminal 2. Specifically, the switching control unit 58 sets the upper limit of the traffic amount (bytes) for each channel to 10% of the Duty ratio per hour, and finally sets the traffic transmitted by the terminal 2 using a plurality of channels to a transmission rate of 10% or more of the Duty ratio by shortening the actual usage time of each channel.

[0060] In step 210 (S210), the switching control unit 58 starts measuring the monitoring time according to the upper limit of the traffic for each channel. The monitoring time (S window ) is the period during which it is monitored whether the limit of 10% of the Duty ratio is being observed for each channel. That is, it is set to a period shorter than the above-mentioned unit time (1 hour), and here it is set to 30 minutes.

[0061] In step 212 (S212), the switching control unit 58 performs control to execute (start or continue) the communication between the terminal 2 and the access point 3.

[0062] In step 214 (S214), the switching control unit 58 determines whether the switching time has elapsed for each channel. If it is determined that the time has elapsed (S214: Yes), the process proceeds to the process of S218. If it is determined that the time has not elapsed (S214: No), the process proceeds to the process of S216.

[0063] In step 216 (S216), the switching control unit 58 determines whether the monitoring time has elapsed. If it is determined that the time has elapsed (S216: Yes), the process returns to the process of S210. If it is determined that the time has not elapsed (S216: No), the process returns to the process of S212.

[0064] In step 218 (S218), the switching control unit 58 performs a channel switch (channel transition) during which communication is being executed, and returns to the process of S206.

[0065] Next, a specific operation example of the wireless communication system 1 according to an embodiment will be described with reference to FIG. 9. FIG. 9 is a diagram showing a specific operation example of the wireless communication system 1 according to an embodiment.

[0066] First, in the wireless communication system 1, before the control device 4 starts switching control, it is assumed that the terminal 2 and the access point 3 are communicating using Ch1 with a width of 1 MHz.

[0067] Next, it is assumed that the control device 4 executes channel switching control and selects Ch11 with a width of 4 MHz and Ch17 with a width of 2 MHz as a channel combination.

[0068] At this time, the transmission capacity of each channel is different. It is assumed that the transmission rate of MCS7 of Ch17 is 6.5 Mbps and the transmission rate of Ch11 is 13.5 Mbps.

[0069] In this case, since the weight coefficient w1 = 0.325 and the weight coefficient w2 = 0.675, using the 4-MHz-wide channel is up to 20.25 minutes in a 30-minute window, and using the 2-MHz-wide channel is up to 9.75 minutes in a 30-minute window.

[0070] Then, the switching control unit 58 repeats the above channel switching until the start time of the next window size (monitoring time) arrives. Therefore, even if the wireless communication system 1 is restricted in the total transmission time of traffic per unit time for each channel, it can achieve transmission with a duty ratio of 10% or more using a plurality of channels while maintaining a constant transmission capacity. That is, even if the wireless communication system 1 is restricted in the total transmission time of traffic per unit time for each channel, it can maximize the transmission capacity within a predetermined range.

[0071] Note that each function of the control device 4 may be partially or entirely configured by hardware such as a PLD (Programmable Logic Device) or an FPGA (Field Programmable Gate Array), or may be configured as a program executed by a processor such as a CPU.

[0072] For example, the control device 4 according to the present invention can be realized using a computer and a program, and it is also possible to record the program on a storage medium or provide it through a network.

[0073] FIG. 10 is a diagram showing a hardware configuration example of the control device 4 according to an embodiment. As shown in FIG. 10, for example, the control device 4 includes an input unit 60, an output unit 61, a communication unit 62, a CPU 63, a memory 64, and an HDD 65 connected via a bus 66, and has functions as a computer. Further, the control device 4 is enabled to input and output data to and from a computer-readable storage medium 67.

[0074] The input unit 60 is, for example, a keyboard and a mouse. The output unit 61 is, for example, a display device such as a display. The communication unit 62 is, for example, a wired or wireless network interface.

[0075] The CPU 63 controls each part constituting the control device 4 and performs predetermined processing and the like. The memory 64 and the HDD 65 are storage devices for storing data and the like. The storage medium 67 is capable of storing a program for causing the control device 4 to execute its functions. Note that the architecture of the control device 4 is not limited to the example shown in FIG. 10.

Explanation of Reference Numerals

[0076] 1... Wireless communication system, 2-1 to 2-N... Terminals, 3... Access point, 4... Control device, 30... Memory, 31... Drive, 32... User interface, 33... Wired communication module, 34-1, 34-2... Wireless communication modules, 35... Timer, 36... Control circuit, 37... Bus, 60... Input section, 61... Output section, 62... Communication section, 63... CPU, 64... Memory, 65... HDD, 66... Bus, 67... Storage medium, 300... Control program, 302... Management information, 310... Storage medium

Claims

1. In a control device that controls a wireless communication system that performs wireless communication using at least one of a plurality of channels, and is restricted by a sum of transmission times for transmitting traffic per unit time for each channel, an evaluation value total calculation unit that calculates the transmission capacity of each channel as an evaluation value, and calculates the total evaluation value of each combination of one or more channels whose frequency bands do not overlap with each other; a selection unit that selects a combination of a predetermined number of channels for which the total evaluation value calculated by the evaluation value total calculation unit is maximized within a predetermined range; a weight coefficient calculation unit that calculates a weight coefficient indicating the ratio of the usage period for each channel included in the combination selected by the selection unit based on the transmission rate or the amount of data that can be transmitted for each channel; a switching time calculation unit that calculates a switching time for switching each channel included in the combination selected by the selection unit based on the weight coefficient calculated by the weight coefficient calculation unit; and a switching control unit that controls to switch the channels included in the combination selected by the selection unit based on each switching time calculated by the switching time calculation unit to transmit traffic. A control device characterized by comprising the above.

2. The switching control unit controls to repeat channel switching within a monitoring time predetermined to be a period shorter than the unit time. The control device according to claim 1, characterized by the above.

3. In a wireless communication method in which a sum of transmission times for transmitting traffic per unit time is restricted for each channel, and wireless communication is performed using at least one of a plurality of channels, an evaluation value total calculation step of calculating the transmission capacity of each channel as an evaluation value, and calculating the total evaluation value of each combination of one or more channels whose frequency bands do not overlap with each other; a selection step of selecting a combination of a predetermined number of channels for which the calculated total evaluation value is maximized within a predetermined range; a weight coefficient calculation step of calculating a weight coefficient indicating the ratio of the usage period for each channel included in the selected combination based on the transmission rate or the amount of data that can be transmitted for each channel; a switching time calculation step of calculating a switching time for switching each channel included in the selected combination based on the calculated weight coefficient; A switching control step of controlling to switch channels included in the selected combination based on each calculated switching time and transmit traffic A wireless communication method characterized by including the above.

4. In the switching control step, Controlling to repeat channel switching within a monitoring time predetermined to be a period shorter than the unit time The wireless communication method according to claim 3, characterized by the above.

5. In a wireless communication system in which a limit is imposed on the total transmission time for transmitting traffic per unit time for each channel, and wireless communication is performed using at least any one of a plurality of channels, An evaluation value total calculation unit that calculates the transmission capacity of each channel as an evaluation value and calculates the total evaluation value of each combination of one or more channels whose frequency bands do not overlap with each other; A selection unit that selects a combination of a predetermined number of channels in which the total evaluation value calculated by the evaluation value total calculation unit is maximized within a predetermined range; A weight coefficient calculation unit that calculates a weight coefficient indicating the ratio of the usage period for each channel included in the combination selected by the selection unit based on the transmission rate or the amount of data that can be transmitted for each channel; A switching time calculation unit that calculates a switching time for switching each channel included in the combination selected by the selection unit based on the weight coefficient calculated by the weight coefficient calculation unit; A switching control unit that controls to switch the channels included in the combination selected by the selection unit based on each switching time calculated by the switching time calculation unit and transmit traffic A wireless communication system characterized by having the above.

6. The switching control unit Controlling to repeat channel switching within a monitoring time predetermined to be a period shorter than the unit time The wireless communication system according to claim 5, characterized by the above.

7. A control program for causing a computer to function as each part of the control device according to claim 1 or 2

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