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

Abstract

Even if the wireless terminal moves and the strength of the received radio waves changes, the application that the wireless terminal uses the received radio waves will continue to run. [Solution] A wireless communication system according to one embodiment sets communication quality conditions necessary for a wireless terminal to execute an application using received radio waves (step S100), estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves (step S102), calculates an index value indicating the degree of satisfaction of the communication quality conditions for each point based on that probability distribution (step S104), and changes the communication settings of the application to be instructed to the wireless terminal based on that index value (steps S106, S108).

Description

Technical Field

[0006] , ,

[0005] ,

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

Background Art

[0002] In a wireless communication system, when a wireless terminal receives radio waves transmitted by a base station, the intensity of the received radio waves varies depending on the location and time. Further, it is desired that the wireless terminal can surely receive radio waves even during movement and receive a stable service.

[0003] For example, in Citation 1, a traffic control method corresponding to a change in the line capacity of a best-effort wireless line is disclosed.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the conventional technology has a problem that it cannot cope with the uncertainty of the received radio wave intensity. For example, in best-effort wireless communication, when a wireless terminal moves to a place where the radio wave intensity becomes weak, the throughput for the terminal may decrease. In this case, since the line capacity decreases, an increase in delay and data loss may occur.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a wireless communication system, a wireless communication control device, a wireless communication control method, and a wireless communication control program that enable a wireless terminal to continue executing an application that utilizes the received radio waves even when the wireless terminal moves and the strength of the received radio waves changes. [Means for solving the problem]

[0007] A wireless communication system according to one embodiment of the present invention comprises a wireless terminal that executes an application using received radio waves while in motion, and a wireless communication control device that controls the wireless communication performed by the wireless terminal, wherein the wireless communication control device includes a setting unit that sets communication quality conditions necessary for the execution of the application, an estimation unit that estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves, a calculation unit that calculates an index value indicating the degree of satisfaction of the communication quality conditions for each point based on the probability distribution, and a modification unit that changes the communication settings of the application instructed to the wireless terminal based on the index value.

[0008] Furthermore, a wireless communication control device according to one embodiment of the present invention is characterized by comprising: a setting unit that sets communication quality conditions necessary for a wireless terminal to execute an application using received radio waves; an estimation unit that estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves; a calculation unit that calculates an index value indicating the degree of satisfaction of the communication quality conditions for each point based on the probability distribution; and a modification unit that changes the communication settings of the application instructed to the wireless terminal based on the index value.

[0009] Furthermore, a wireless communication control method according to one embodiment of the present invention is characterized by including a setting step of setting communication quality conditions necessary for a wireless terminal to execute an application using received radio waves; an estimation step of estimating the probability distribution of communication quality at each point in the space in which the wireless terminal moves; a calculation step of calculating an index value indicating the degree of satisfaction of the communication quality conditions for each point based on the probability distribution; and a modification step of changing the communication settings of the application instructed to the wireless terminal based on the index value.

[0010] Furthermore, a wireless communication control program according to one embodiment of the present invention causes a computer to function as each part of a wireless communication control device, which includes a setting unit that sets communication quality conditions necessary for a wireless terminal to execute an application using received radio waves, an estimation unit that estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves, a calculation unit that calculates an index value indicating the degree of satisfaction of the communication quality conditions for each point based on the probability distribution, and a modification unit that changes the communication settings of the application instructed to the wireless terminal based on the index value. [Effects of the Invention]

[0011] According to the present invention, even if the wireless terminal moves and the strength of the received radio waves changes, the wireless terminal can continue to execute the application that utilizes the received radio waves. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example configuration of a wireless communication control device according to one embodiment. [Figure 2] This flowchart shows an example of the operation of a wireless communication control device. [Figure 3] This is a graph illustrating a probability distribution. [Figure 4] This figure shows an example of the hardware configuration of a wireless communication control device according to one embodiment. [Modes for carrying out the invention]

[0013] The following describes a wireless communication system and wireless communication control device according to one embodiment. The wireless communication system, which includes a wireless terminal that receives radio waves transmitted by a base station, is equipped with a wireless communication control device and provides a continuously stable wireless communication service to the mobile wireless terminal. The wireless terminal, for example, runs an application that uses the received radio waves while moving. The wireless communication control device controls the wireless communication performed by the wireless terminal.

[0014] Figure 1 shows an example of the configuration of a wireless communication control device 10 according to one embodiment. As shown in Figure 1, the wireless communication control device 10 includes, for example, a setting unit 20, an estimation unit 22, a calculation unit 24, and a modification unit 26.

[0015] The setting unit 20 sets the communication quality conditions necessary for the wireless terminal to execute an application that uses received radio waves. In one embodiment, the setting unit 20 sets the radio wave strength corresponding to the amount of traffic required to execute the application along the travel path of the moving wireless terminal. For example, the setting unit 20 sets the travel path of the wireless terminal and the radio wave strength required at each point along the travel path.

[0016] The estimation unit 22 estimates the probability distribution of communication quality at each point in the space in which the wireless terminal is moving. In one embodiment, the estimation unit 22 estimates the probability that the strength of the radio waves received by the wireless terminal will be less than a predetermined value along the travel path as a probability distribution along the travel path. For example, the estimation unit 22 estimates the radio wave strength at each point along the travel path of the wireless terminal as a probability distribution.

[0017] For example, the estimation unit 22 may be configured to estimate the probability distribution quickly by dividing the radio wave intensity into a linear term and a probability term. The linear term may use only the expected value, or a term that can be measured quickly, such as the beam direction. The probability term may be a term that takes time to process, such as a probability distribution or an event independent of the beam direction.

[0018] Further, the estimation unit 22 may improve the accuracy of estimation by using, for example, a Gaussian Process Regression (GPR) kernel function in a three-dimensional orthogonal coordinate system or a polar coordinate system centered on the antenna. Further, the estimation unit 22 may use a multidimensional scaling method (MDS) to expand the three-dimensional space into a higher dimension, and represent the non-uniformity of the spatial structure such as NLOS / LOS in terms of a distance scale in the higher-dimensional space.

[0019] Based on the probability distribution estimated by the estimation unit 22, the calculation unit 24 calculates an index value indicating the degree of satisfaction of the communication quality condition set by the setting unit 20 for each location. In one embodiment, the calculation unit 24 calculates the probability of falling below the radio wave intensity set by the setting unit 20 on the movement path based on the probability distribution on the movement path estimated by the estimation unit 22. For example, the calculation unit 24 calculates the probability that the communication quality requirements cannot be met at each location on the movement path of the wireless terminal.

[0020] Based on the index value calculated by the calculation unit 24, the change unit 26 changes the communication settings of the application instructed to the wireless terminal. In one embodiment, when the probability that the communication quality of the wireless terminal drops below a predetermined value exceeds a predetermined probability based on the probability on the movement path calculated by the calculation unit 24, the change unit 26 changes the setting of the traffic volume required for the execution of the application according to the throughput for the wireless terminal.

[0021] For example, when the application executed by the wireless terminal reproduces a received image, the change unit 26 changes the setting to reduce the bit rate or frame rate of the image transmitted by the application, and performs traffic control to avoid interruption of the image.

[0022] Further, the change unit 26 may be configured to re-set the application settings according to the quality when the decrease in communication quality exceeds a certain probability based on the probability calculated by the calculation unit 24.

[0023] Furthermore, if the wireless communication control device 10 is a system that transmits video of a moving surveillance robot, it can maintain stable service quality so that the video is never interrupted along the path the surveillance robot is traveling.

[0024] Next, an example of the operation of the wireless communication control device 10 will be described. Figure 2 is a flowchart showing an example of the operation of the wireless communication control device 10.

[0025] In step 100 (S100), the wireless communication control device 10 sets the movement path of the wireless terminals for which maintaining wireless communication quality is necessary, and the radio wave strength that can be expected from the application.

[0026] In step 102 (S102), the wireless communication control device 10 estimates the probability distribution of radio wave intensity at each point along the travel path and saves it as a map.

[0027] In step 104 (S104), the wireless communication control device 10 calculates the probability that the required quality requirements cannot be met along the travel path.

[0028] In step 106 (S106), the wireless communication control device 10 calculates the application settings based on the calculated probability if the deterioration of communication quality exceeds a predetermined probability.

[0029] In step 108 (S108), the wireless communication control device 10 readjusts the application settings to match the quality.

[0030] In this way, the wireless communication control device 10 changes the setting of the amount of traffic required to execute the application according to the throughput to the wireless terminal, based on the probability on the movement path calculated by the calculation unit 24. Therefore, even if the wireless terminal moves and the strength of the received radio waves changes, the wireless terminal can continue to execute the application that uses the received radio waves.

[0031] In other words, the wireless communication control device 10 can realize robust wireless communication in a wireless communication system. For example, as shown in the probability distribution in Figure 3, the wireless communication control device 10 determines the radio wave strength at each point along the wireless terminal's travel path as a distribution. Then, the wireless communication control device 10 determines the relationship between each point and the probability B that the radio wave strength will be greater than or equal to a predetermined value A.

[0032] At this time, the wireless communication control device 10 sets two parameters, radio wave strength and accuracy, to change for each location along the wireless terminal's travel path. For example, the wireless communication control device 10 sets the radio wave strength to correspond to the expected traffic demand for each location along the wireless terminal's travel path. The wireless communication control device 10 also sets the accuracy for each location along the wireless terminal's travel path according to the importance and risk of each location.

[0033] As a specific example, if the wireless communication system is a system that transmits video of a moving surveillance robot, the wireless communication control device 10 performs a PDF analysis of the radio wave intensity at the location of the surveillance robot where quality assurance is required in the wireless communication system, and calculates the probability that the radio wave intensity will be higher than a given radio wave intensity.

[0034] In this case, the wireless communication control device 10 can set the required accuracy of the radio wave strength based on probability, according to the communication quality required for the application. In other words, the wireless communication control device 10 can always maintain an appropriate margin (dB) of radio wave strength by using the distribution of radio wave strength, rather than determining the radio wave strength by a threshold.

[0035] Furthermore, the wireless communication control device 10 may acquire radio wave conditions in real time through online measurement or cloud sensing, and update the learned distribution of radio wave strength online even while the wireless communication system is in operation.

[0036] Furthermore, the wireless communication control device 10 may extend the distribution of radio wave intensity to a four-dimensional spatiotemporal map that also includes the time axis, and predict the future distribution of radio wave intensity. For example, in the time axis direction, the wireless communication control device 10 may predict daily or weekly fluctuations by using a periodic function as the kernel function.

[0037] Thus, the wireless communication control device 10 according to one embodiment can continue the execution of an application that utilizes the received radio waves even when the wireless terminal moves and the strength of the received radio waves changes.

[0038] The following describes a more specific embodiment of the wireless communication control device 10.

[0039] <First Example> The first embodiment is a case in which the movement path of the wireless terminal is pre-configured in the wireless communication control device 10, and the wireless terminal can change its throughput.

[0040] The configuration unit 20 pre-sets the target probability of achieving the desired communication quality along the wireless terminal's travel path as a communication quality condition necessary for the execution of the application. For example, the configuration unit 20 pre-sets the travel path of the wireless terminal and the target throughput achievement probability (or signal strength achievement probability) along that travel path.

[0041] The calculation unit 24 calculates, based on the probability distribution of communication quality at each point in the space in which the wireless terminal moves, the minimum communication quality at which the target achievement probability can be achieved for each point along the wireless terminal's movement path, as an index value indicating the degree to which the communication quality conditions are satisfied.

[0042] The modification unit 26 modifies the communication settings of the application instructed to the wireless terminal so that the minimum communication quality calculated by the calculation unit 24 is met at each point along the wireless terminal's travel path. For example, the modification unit 26 notifies the wireless terminal of the throughput (or radio wave strength) that can be achieved at or above the target success probability at each point along the wireless terminal's travel path.

[0043] Upon receiving notification from the wireless communication control device 10, the wireless terminal either permanently sets the throughput to the minimum throughput achievable along the travel path, or dynamically changes it as needed to the throughput achievable at each point along the travel path. Alternatively, the wireless terminal changes the video encoding rate to a video encoding rate that corresponds to the achievable throughput.

[0044] <Second Example> The second embodiment is a case in which the movement path of the wireless terminal is pre-configured in the wireless communication control device 10, and the wireless terminal cannot change the throughput.

[0045] The configuration unit 20 pre-sets the target communication quality along the wireless terminal's travel path as a communication quality condition necessary for the execution of the application. For example, the configuration unit 20 pre-sets the route along which the wireless terminal travels and the target throughput (or signal strength) along that route.

[0046] The calculation unit 24 calculates the probability of achieving the target communication quality for each point along the wireless terminal's travel path, based on the probability distribution of communication quality at each point in the space in which the wireless terminal is moving, as an index value indicating the degree to which the communication quality conditions are satisfied.

[0047] The modification unit 26 modifies the communication settings of an application that instructs the wireless terminal to either notify the wireless terminal of the probability of achieving the target communication quality at each point along the wireless terminal's travel path, or to stop communication at points where the probability of achieving the target communication quality is below a predetermined value. For example, the modification unit 26 notifies the wireless terminal of the probability of achieving the target throughput (or signal strength) at each point along the wireless terminal's travel path.

[0048] Upon receiving notification from the wireless communication control device 10, the wireless terminal will either refrain from communication at locations along its travel path where the probability of achieving the target throughput (or signal strength) is low, or take measures such as reconsidering its travel path.

[0049] <Third Example> The third embodiment is a case in which the current location of the wireless terminal is notified to the wireless communication control device 10 in real time, and the wireless terminal can change its throughput.

[0050] The configuration unit 20 sets the target communication quality achievement probability at the wireless terminal's current location in real time as a communication quality condition necessary for the execution of the application. For example, the configuration unit 20 sets the wireless terminal's current location and the target throughput achievement probability (or signal strength achievement probability) at the current location in real time.

[0051] The calculation unit 24 calculates the minimum communication quality at which the target achievement probability can be achieved for the current location of the wireless terminal, based on the probability distribution of communication quality at each point in the space in which the wireless terminal is moving, as an index value indicating the degree to which the communication quality conditions are satisfied.

[0052] The modification unit 26 either notifies the wireless terminal of the probability of achieving the target communication quality at each point along the wireless terminal's travel path, or modifies the communication settings of the application instructing the wireless terminal so that the minimum communication quality is met at the current location of the target communication quality. For example, the modification unit 26 notifies the wireless terminal of the throughput (or signal strength) that can be achieved at the current location of the wireless terminal with a probability of achieving the target or higher.

[0053] Upon receiving notification from the wireless communication control unit 10, the wireless terminal changes the throughput in real time to a throughput achievable at the current location (or the expected destination), or changes the video encoding rate to a video encoding rate that corresponds to the achievable throughput.

[0054] <Fourth Example> The fourth embodiment is a case in which the current location of the wireless terminal is notified to the wireless communication control device 10 in real time, and the wireless terminal cannot change its throughput.

[0055] The configuration unit 20 sets the target communication quality at the current location of the wireless terminal in real time as a communication quality condition necessary for the execution of the application. For example, the configuration unit 20 sets the current location of the wireless terminal and the target throughput (or signal strength) at the current location in real time.

[0056] The calculation unit 24 calculates the probability of achieving the target communication quality for the current location of the wireless terminal, based on the probability distribution of communication quality at each point in the space in which the wireless terminal is moving, as an index value indicating the degree to which the communication quality conditions are satisfied.

[0057] The modification unit 26 modifies the communication settings of an application that instructs the wireless terminal to either notify the wireless terminal of the probability of achieving the target communication quality at the wireless terminal's current location, or to stop communication if the probability of achieving the target communication quality at the current location is below a predetermined value. For example, the modification unit 26 notifies the wireless terminal of the probability of achieving the target throughput (or signal strength) at the wireless terminal's current location.

[0058] Upon receiving notification from the wireless communication control device 10, the wireless terminal takes necessary measures such as suspending communication in real time at locations where the probability of achieving the target throughput (or signal strength) is low, or changing its travel route.

[0059] Furthermore, each function of the wireless communication control device 10 may be partially or entirely composed of hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array), or it may be composed of a program executed by a processor such as a CPU.

[0060] For example, the wireless communication control device 10 can be implemented using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0061] Figure 4 shows an example of the hardware configuration of a wireless communication control device 10 according to one embodiment. As shown in Figure 4, for example, the wireless communication control device 10 has an input unit 50, an output unit 51, a communication unit 52, a CPU 53, a memory 54, and an HDD 55 connected via a bus 56, and is equipped with computer functions. The wireless communication control device 10 is also configured to be able to input and output data to and from a computer-readable storage medium 57.

[0062] The input unit 50 is, for example, a keyboard and mouse. The output unit 51 is, for example, a display device such as a display that outputs images. The communication unit 52 is, for example, a wireless network interface and may also have the function of an output unit that outputs data to the outside.

[0063] As described above, the CPU 53 controls each component of the wireless communication control device 10 and performs predetermined processing. The memory 54 and HDD 55 are storage units that store data, etc.

[0064] The storage medium 57 is capable of storing programs and the like that which cause the wireless communication control device 10 to execute its functions. Note that the architecture of the wireless communication control device 10 is not limited to the example shown in Figure 4. [Explanation of Symbols]

[0065] 10... Wireless communication control unit, 20... Setting unit, 22... Estimation unit, 24... Calculation unit, 26... Change unit, 50... Input unit, 51... Output unit, 52... Communication unit, 53... CPU, 54... Memory, 55... HDD, 56... Bus, 57... Storage medium

Claims

1. A wireless communication system comprising a wireless terminal that executes an application using received radio waves while in motion, and a wireless communication control device that controls the wireless communication performed by the wireless terminal, The aforementioned wireless communication control device is A setting unit for setting communication quality conditions necessary for the execution of the aforementioned application, An estimation unit that estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves, A calculation unit calculates an index value for each location that indicates the degree of satisfaction of the communication quality conditions based on the probability distribution, A modification unit that modifies the communication settings of the application to be instructed to the wireless terminal based on the aforementioned index value. A wireless communication system characterized by having the following features.

2. The setting unit pre-sets the probability of achieving the target communication quality along the wireless terminal's travel path as a communication quality condition. The calculation unit calculates, based on the probability distribution, the minimum communication quality that can achieve the target achievement probability for each point along the travel path as the index value, The modification unit modifies the communication settings at each point along the travel path so that the minimum communication quality is met. The wireless communication system according to claim 1.

3. The setting unit pre-sets the target communication quality along the wireless terminal's travel path as the communication quality condition. The calculation unit calculates, based on the probability distribution, the probability of achieving the target communication quality as the index value for each point along the travel path. The modification unit either notifies the wireless terminal of the probability of achievement at each point along the travel route, or modifies the communication settings to stop communication at points where the probability of achievement is below a predetermined value. The wireless communication system according to claim 1.

4. The setting unit sets the probability of achieving the target communication quality at the current location of the wireless terminal in real time as the communication quality condition. The calculation unit calculates, based on the probability distribution, the minimum communication quality at which the target achievement probability can be achieved as the index value for the current location. The modification unit modifies the communication settings so that the minimum communication quality is met at the current location. The wireless communication system according to claim 1.

5. The setting unit sets the target communication quality at the current location of the wireless terminal in real time as the communication quality condition. The calculation unit calculates the probability of achieving the target communication quality as the index value for the current location based on the probability distribution. The modification unit either notifies the wireless terminal of the probability of success at the current location, or modifies the communication settings to stop communication if the probability of success at the current location is less than or equal to a predetermined value. The wireless communication system according to claim 1.

6. A setting unit that sets the communication quality conditions necessary for a wireless terminal to run an application that uses received radio waves, An estimation unit that estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves, A calculation unit calculates an index value for each location that indicates the degree of satisfaction of the communication quality conditions based on the probability distribution, A modification unit that modifies the communication settings of the application to be instructed to the wireless terminal based on the aforementioned index value. A wireless communication control device characterized by having the following features.

7. A configuration process for setting the communication quality conditions necessary for a wireless terminal to run an application that uses received radio waves, An estimation step for estimating the probability distribution of communication quality at each point in the space in which the wireless terminal moves, A calculation step of calculating an index value indicating the degree of satisfaction of the communication quality conditions for each location based on the probability distribution, A modification step of changing the communication settings of the application that instructs the wireless terminal based on the aforementioned index value, and A wireless communication control method characterized by including the following.

8. A setting unit that sets the communication quality conditions necessary for a wireless terminal to run an application that uses received radio waves, An estimation unit that estimates the probability distribution of communication quality at each point in the space in which the wireless terminal moves, A calculation unit calculates an index value for each location that indicates the degree of satisfaction of the communication quality conditions based on the probability distribution, A modification unit that modifies the communication settings of the application to be instructed to the wireless terminal based on the aforementioned index value. A wireless communication control program for causing a computer to function as one of the components of a wireless communication control device having [a specific feature / function].

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