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

Abstract

Even if the wireless terminal moves, the application that uses the received radio waves on that wireless terminal 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 the probability distribution (step S104), calculates the beam angle of the base station based on the index value (step S106), and sets the calculated beam angle for the base station (step S108).

Description

Technical Field

[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 Cited Document 1, an optimization technique for antenna beam tilting in mobile communication 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 prior art has a problem that it cannot cope with the uncertainty of the received radio wave intensity. For example, when a wireless terminal moves, an event may occur in which the requirements for communication quality cannot be satisfied on the movement path of the wireless terminal.

[0006] The present invention has been made in view of the above-described problems, and an object thereof is to provide a wireless communication system, a wireless communication control device, a wireless communication control method, and a wireless communication control program that can continue the execution of an application that uses received radio waves by the wireless terminal even when the wireless terminal moves. [Means for solving the problem]

[0007] A wireless communication system according to one embodiment of the present invention comprises a base station that transmits radio waves to a wireless terminal that performs an application using received radio waves while in motion, and a wireless communication control device that controls the base station, 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, a beam angle calculation unit that calculates the beam angle of the base station based on the index value, and a base station setting unit that sets the beam angle calculated by the beam angle calculation unit for the base station.

[0008] Furthermore, a wireless communication control device according to one embodiment of the present invention is a wireless communication control device that controls a base station that transmits radio waves to a wireless terminal that executes an application using received radio waves while in motion, and is characterized by comprising: 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; a beam angle calculation unit that calculates the beam angle of the base station based on the index value; and a base station setting unit that sets the beam angle calculated by the beam angle calculation unit for the base station.

[0009] Furthermore, a wireless communication control method according to one embodiment of the present invention is a wireless communication control method for controlling a base station that transmits radio waves to a wireless terminal that executes an application using received radio waves while moving, and is characterized by including a setting step of setting communication quality conditions necessary for the execution of the application; 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; a beam angle calculation step of calculating the beam angle of the base station based on the index value; and a base station setting step of setting the beam angle calculated in the beam angle calculation step for the base station.

[0010] Furthermore, a wireless communication control program according to one embodiment of the present invention is a wireless communication control program executed by a wireless communication control device that controls a base station that transmits radio waves to a wireless terminal that executes an application using received radio waves while in motion, and each of the units of the wireless communication control device having 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, a beam angle calculation unit that calculates the beam angle of the base station based on the index value, and a base station setting unit that sets the beam angle calculated by the beam angle calculation unit for the base station, is configured to function as a computer. [Effects of the Invention]

[0011] According to the present invention, even if the wireless terminal moves, 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 a mobile wireless terminal.

[0014] The base station transmits radio waves to wireless terminals. Wireless terminals, for example, run applications that utilize the received radio waves while on the move. The wireless communication control unit performs control over the base station.

[0015] 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 travel path setting unit 20, a setting unit 21, an estimation unit 22, a calculation unit 23, a beam angle calculation unit 24, and a base station setting unit 25.

[0016] The movement path setting unit 20 sets the movement path of the wireless terminal within a predetermined area.

[0017] The setting unit 21 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 21 sets the radio wave strength corresponding to the amount of traffic required to execute the application along the wireless terminal's travel path. For example, the setting unit 21 sets the required radio wave strength at each point along the travel path.

[0018] The estimation unit 22 estimates the probability distribution of the communication quality at each point in the space where the wireless terminal moves. In one embodiment, the estimation unit 22 estimates, as the probability distribution on the movement path, the probability that the intensity of the radio wave received by the wireless terminal becomes less than a predetermined value on the movement path. For example, the estimation unit 22 estimates the radio wave intensity at each point on the movement path of the wireless terminal as a probability distribution. Also, the estimation unit 22 may estimate the probability distribution even while the wireless terminal is moving.

[0019] For example, the estimation unit 22 may be configured to estimate the probability distribution at high speed by dividing the radio wave intensity into a linear term and a probability term. The linear term may use, for example, only the expected value or a term that can be measured at high speed such as the direction of the beam. Also, the probability term may be a term that requires time for processing, such as a probability distribution or an event independent of the direction of the beam.

[0020] Also, the estimation unit 22 may perform high-precision estimation using, for example, a GPR (Gaussian Process Regression) kernel function in a three-dimensional orthogonal coordinate system or a polar coordinate system centered on the antenna. Also, the estimation unit 22 may use the multidimensional scaling method (MDS) to expand the three-dimensional space into a high-dimensional space, and represent the non-uniformity of the space structure such as NLOS / LOS in terms of the distance scale in the high-dimensional space.

[0021] The calculation unit 23 calculates, for each point, an index value indicating the degree of satisfaction of the communication quality condition set by the setting unit 20 based on the probability distribution estimated by the estimation unit 22. In one embodiment, based on the probability distribution on the movement path estimated by the estimation unit 22, the probability of becoming less than the radio wave intensity set by the setting unit 21 on the movement path is calculated. For example, the calculation unit 23 calculates the probability that the requirements for communication quality cannot be satisfied at each point on the movement path of the wireless terminal.

[0022] The beam angle calculation unit 24 calculates the beam angle of the base station based on the index value calculated by the calculation unit 23. In one embodiment, the beam angle that satisfies the necessary communication quality in the wireless communication system of the base station is calculated so as to minimize the probability on the movement path calculated by the calculation unit 23 at each point on the movement path.

[0023] The base station setting unit 25 sets the beam angle calculated by the beam angle calculation unit 24 for the base station.

[0024] Note that the wireless communication control device 10 may be configured to repeatedly and rapidly process the steps in which the estimation unit 22 estimates the probability distribution, the calculation unit 23 calculates the probability that the communication quality requirements cannot be satisfied, and the beam angle calculation unit 24 calculates the beam angle that satisfies the communication quality, and optimize the beam direction in real time while the wireless terminal is moving.

[0025] When the wireless communication control device 10 is a system for transmitting the video of the monitoring robot that the wireless communication system moves, it can maintain a stable service quality so that the video is never interrupted on the path where the monitoring robot moves. Also, the wireless communication control device 10 can guarantee the communication quality at important locations such as places where people gather.

[0026] Next, an operation example of the wireless communication control device 10 will be described. FIG. 2 is a flowchart showing an operation example of the wireless communication control device 10.

[0027] In step 100 (S100), the wireless communication control device 10 sets the movement path of the wireless terminal that requires quality maintenance of wireless communication and the radio wave intensity considered from the application.

[0028] In step 102 (S102), the wireless communication control device 10 estimates the probability distribution of the radio wave intensity at each point on the movement path and saves it as a map.

[0029] In step 104 (S104), the wireless communication control device 10 calculates the probability that the necessary quality requirements cannot be satisfied on the movement path.

[0030] In step 106 (S106), the wireless communication control device 10 calculates the beam angle that minimizes the probability that the necessary communication quality cannot be satisfied.

[0031] In step 108 (S108), the wireless communication control device 10 sets the calculated beam angle to the base station.

[0032] In this way, the wireless communication control device 10 calculates the beam angle of the base station to minimize the probability along the movement path calculated by the calculation unit 23 and sets it to the base station, so that even if the wireless terminal moves, the wireless terminal can continue to execute the application that uses the received radio waves.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Thus, the wireless communication control device 10 according to one embodiment can continue the execution of an application that utilizes the received radio waves of a wireless terminal, even when the wireless terminal moves. Furthermore, the wireless communication control device 10 can also be used for beamforming optimization, multiple beamforming optimization, base station layout design, additional base station design, and mobile base station layout design.

[0040] The following describes a more specific embodiment of the wireless communication control device 10.

[0041] <First Example> The first embodiment is a case in which the movement path of a wireless terminal is pre-set in the wireless communication control device 10, and the objective is to increase the number of locations that meet the quality conditions as much as possible.

[0042] The configuration unit 21 pre-sets the target communication quality and the probability of achieving that target along the wireless terminal's travel path as communication quality conditions necessary for the execution of the application. For example, the configuration unit 21 pre-sets the route along which the wireless terminal travels, the target throughput (or signal strength) along that route, and the probability of achieving that throughput.

[0043] The calculation unit 23 calculates the number of target-achievable locations where the target communication quality can be achieved with a target achievement probability of or higher, as an index value indicating the degree of satisfaction of the communication quality conditions, based on the probability distribution of communication quality at each point in the space in which the wireless terminal moves.

[0044] The beam angle calculation unit 24 calculates the beam angle (one beam or multiple beams) that maximizes the number of target achievable locations.

[0045] <Second Example> The second embodiment is a case in which the communication quality that can be achieved at all locations is maximized when the movement path of the wireless terminal is pre-set in the wireless communication control device 10.

[0046] The configuration unit 21 pre-sets the probability of achieving a 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 21 pre-sets the path along which the wireless terminal travels and the probability of achieving a target throughput (or signal strength) along that path.

[0047] The calculation unit 23 calculates the minimum communication quality achievable with the target probability at all points along the wireless terminal's movement path as an index value indicating the degree of satisfaction of the communication quality conditions, based on the probability distribution of communication quality at each point in the space in which the wireless terminal is moving. However, instead of calculating the minimum communication quality achievable with the target probability at all points, the average value of the communication quality achievable with the target probability at all points may be calculated.

[0048] The beam angle calculation unit 24 calculates the beam angle (one beam or multiple beams) that maximizes the minimum communication quality achievable with the target success probability at all locations. For example, the beam angle calculation unit 24 calculates the beam angle that maximizes the throughput (or radio wave intensity) achievable with the target success probability at all locations.

[0049] <Third Example> The third embodiment is a case in which the current location of a wireless terminal is notified to the wireless communication control device 10 in real time, and the objective is to increase as much as possible the number of wireless terminals that meet the communication quality conditions.

[0050] The configuration unit 21 sets, in real time, the target communication quality and the probability of achieving that target at the current location of each of the multiple wireless terminals as communication quality conditions necessary for the execution of the application. For example, the configuration unit 21 sets, in real time, the current location of each of the multiple wireless terminals, the target throughput (or signal strength), and the probability of achieving it.

[0051] The calculation unit 23 calculates, based on the probability distribution of communication quality at each point in the space in which the wireless terminals are moving, the number of wireless terminals that achieve the target communication quality among multiple wireless terminals, in which the probability of achieving the target communication quality is equal to or greater than the target achievement probability, as an index value indicating the degree of satisfaction of the communication quality conditions.

[0052] The beam angle calculation unit 24 calculates the beam angle (one beam or multiple beams) that maximizes the number of target-achieving wireless terminals.

[0053] <Fourth Example> The fourth embodiment is a case in which the current location of a wireless terminal is notified to the wireless communication control device 10 in real time, and the objective is to maximize the communication quality that can be met by all wireless terminals.

[0054] The configuration unit 21 sets, in real time, the probability of achieving the target communication quality at the current location of each of the multiple wireless terminals as a communication quality condition necessary for the execution of the application. For example, the configuration unit 21 sets, in real time, the current location of the wireless terminal and the probability of achieving the target throughput (or signal strength) at the current location.

[0055] The calculation unit 23 calculates the minimum communication quality achievable with the target probability for all of the multiple wireless terminals, based on the probability distribution of communication quality at each point in the space in which the wireless terminals are moving, as an index value indicating the degree of satisfaction of the communication quality conditions. However, instead of calculating the minimum communication quality achievable with the target probability for all wireless terminals, the average value of the communication quality achievable with the target probability for all wireless terminals may be calculated.

[0056] The beam angle calculation unit 24 calculates the beam angle (one beam or multiple beams) that maximizes the minimum communication quality achievable with the target success probability for all wireless terminals. For example, the beam angle calculation unit 24 calculates the beam angle that maximizes the throughput (or radio wave intensity) achievable with the target success probability for all wireless terminals.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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]

[0063] 10... Wireless communication control device, 20... Travel path setting unit, 21... Setting unit, 22... Estimation unit, 23... Calculation unit, 24... Beam angle calculation unit, 25... Base station setting 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 base station that transmits radio waves to a wireless terminal that runs an application using received radio waves while on the move, and a wireless communication control device that controls the base station, 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 beam angle calculation unit that calculates the beam angle of the base station based on the aforementioned index value, A base station setting unit sets the beam angle calculated by the beam angle calculation unit to the base station. A wireless communication system characterized by having the following features.

2. The setting unit pre-sets the target communication quality along the wireless terminal's travel path and the probability of achieving that target as communication quality conditions. The calculation unit calculates, based on the probability distribution, the number of target-achievable locations where the target communication quality can be achieved at or above the target achievement probability, as the index value. The beam angle calculation unit calculates the beam angle that maximizes the number of points where the target can be achieved. The wireless communication system according to claim 1.

3. 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 achievable at all points along the travel path with the target achievement probability as the index value. The beam angle calculation unit calculates the beam angle that maximizes the minimum communication quality. The wireless communication system according to claim 1.

4. The setting unit sets, in real time, the target communication quality and the probability of achieving that target at the current location of each of the multiple wireless terminals as the communication quality conditions. The calculation unit calculates, based on the probability distribution, the number of target-achieving wireless terminals among the plurality of wireless terminals for which the probability of achieving the target communication quality is equal to or greater than the target achievement probability, as the index value. The beam angle calculation unit calculates the beam angle that maximizes the number of wireless terminals that achieve the target. The wireless communication system according to claim 1.

5. The setting unit sets the probability of achieving the target communication quality at the current location of each of the multiple wireless terminals in real time as the communication quality condition. The calculation unit calculates, based on the probability distribution, the minimum communication quality that can be achieved with the target achievement probability for all of the plurality of wireless terminals as the index value. The beam angle calculation unit calculates the beam angle that maximizes the minimum communication quality. The wireless communication system according to claim 1.

6. In a wireless communication control device that controls a base station that transmits radio waves to a wireless terminal that runs an application using received radio waves while on the move, 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 beam angle calculation unit that calculates the beam angle of the base station based on the aforementioned index value, A base station setting unit sets the beam angle calculated by the beam angle calculation unit to the base station. A wireless communication control device characterized by having the following features.

7. In a wireless communication control method for controlling a base station that transmits radio waves to a wireless terminal that runs an application using received radio waves while on the move, A setting step for setting the communication quality conditions necessary for the execution of the aforementioned application, 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 beam angle calculation step, which calculates the beam angle of the base station based on the aforementioned index value, A base station setting step in which the beam angle calculated in the beam angle calculation step is set for the base station. A wireless communication control method characterized by including the following.

8. In a wireless communication control program executed by a wireless communication control device that controls a base station that transmits radio waves to a wireless terminal that runs an application using received radio waves while on the move, 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 beam angle calculation unit that calculates the beam angle of the base station based on the aforementioned index value, A base station setting unit sets the beam angle calculated by the beam angle calculation unit to the base station. A wireless communication control program for causing a computer to function as one of the components of the wireless communication control device having the above-mentioned features.

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