Information processing device, system, method and program

Abstract

To provide an information processing device capable of interpolating a radio wave map.SOLUTION: According to an embodiment, an information processing device includes a processing unit. The processing device, based on the status of a propagation path including time fluctuations between a first radio device that moves in a predetermined geographical range and a second radio device that forms a radio communication area including the predetermined geographical range, generates data of a missing portion on a radio map on which data on received power at each point in the predetermined geographical range is mapped.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an information processing device, a system, a method, and a program. [Background technology]

[0002] In recent years, the fifth-generation mobile communication system (5G) has been attracting attention. With the widespread adoption of 5G, it is predicted that the introduction of mobile edge computing (MEC) will progress in factories, distribution centers, and other locations. For example, it is expected that the transportation of goods and other items using autonomous mobile robots (AMRs) that adaptively select routes will become mainstream, replacing auto-guided vehicles (AGVs) that move along predetermined routes.

[0003] Currently, the category of AMR includes not only autonomously operating transport robots, but also transport robots that operate based on external instructions. The latter type of AMR communicates with an MEC server. More specifically, AMRs communicate wirelessly with base stations (access points) installed in factories or distribution centers, for example.

[0004] To move AMRs along appropriate routes within a factory, distribution center, etc. under the control of an MEC server, it is necessary to ensure smooth communication between the MEC server and the AMR at all times, or more specifically, smooth wireless communication between a base station and the AMR. Various technologies have been proposed to ensure smooth wireless communication. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-140585 [Non-patent literature]

[0006] [Non-Patent Document 1] A. Narzullaev, Y. Park, K. Yoo, and J. Yu, A fast and accurate calibration algorithm for real-time locating systems based on the received signal strength indication. AEU Int J Electron Commun 65(4):305-311 Summary of the Invention [Problem to be solved by the invention]

[0007] As a step to move AMRs along appropriate routes, a radio wave map is sometimes generated using the AMR, which maps data on the received power at each location within a factory, distribution center, etc., for wireless communication between a base station and the AMR. When generating this radio wave map, it is important to know how to fill in any missing data that may occur on the radio wave map.

[0008] One embodiment of the present invention provides an information processing device, system, method, and program capable of interpolating a radio wave map. [Means for solving the problem]

[0009] According to an embodiment, an information processing device includes a processing unit that generates data for missing portions on a radio wave map on which data related to received power at each point within a predetermined geographical range is mapped, based on a propagation path status, including time fluctuations, between a first radio device moving within a predetermined geographical range and a second radio device communicating with the first radio device. The processing unit determines the state of the propagation path based on the difference between a first received power measured at the first radio device side and a second received power measured at the second radio device side. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an information processing apparatus according to an embodiment. [Figure 2]FIG. 1 is a diagram illustrating an application example of an information processing apparatus according to an embodiment. [Figure 3] A diagram showing an example of a radio wave map obtained using the Friis propagation formula. [Figure 4] A diagram showing an example of a radio wave map with missing parts [Figure 5] FIG. 10 is a diagram showing an example of a radio wave map including fluctuation components. [Figure 6] FIG. 1 is a diagram showing an example of a radio wave map that includes fluctuation components and has missing parts; [Figure 7] 1 is a diagram showing an example of a radio wave map that tracks short-term fluctuations in comparison with a radio wave map that tracks instantaneous fluctuations; [Figure 8] FIG. 10 is a diagram illustrating an example of acquiring received power in the information processing apparatus according to the embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of actual measurement values of a radio wave map in the information processing apparatus according to the embodiment. [Figure 10] A plot of the relationship between distance from the access point and RSSI for route [1] (Y=0) in Figure 9. [Figure 11] A plot of the relationship between distance from the access point and RSSI for route [2] (Y=3) in Figure 9. [Figure 12] A plot of the relationship between distance from the access point and RSSI for route [3] (Y=6) in Figure 9. [Figure 13] FIG. 10 is a diagram showing an example of the result of applying interpolation to the route [2] (Y=3) in FIG. 9. [Figure 14] FIG. 10 is a diagram showing a cumulative probability distribution of errors in interpolation of a radio wave map by the information processing apparatus according to the embodiment; [Figure 15] 1 is a flowchart showing an operation procedure of an information processing apparatus according to an embodiment; [Figure 16] A flowchart showing the procedure for selectively using interpolation methods in radio wave map interpolation in S103 of FIG. 15. [Figure 17] FIG. 10 is a diagram illustrating a modified example of the information processing apparatus according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the drawings. 1 is a diagram illustrating an example of the configuration of an information processing device 1 according to an embodiment. Application examples of the information processing device 1 will be described later, but the information processing device 1 is a device that generates a radio wave map for AMR route selection in a factory, a distribution center, etc. When generating the radio wave map, the information processing device 1 according to the embodiment has a function of appropriately interpolating missing portions of data on the radio wave map, which will be described in detail below.

[0012] 1, the information processing device 1 includes an acquisition unit 10, a processing unit 20, a storage unit 30, and an output unit 40. The processing unit 20 includes a control unit 21, a radio wave map generation unit 22, a propagation path status assessment unit 23, and a radio wave map interpolation unit 24.

[0013] The acquisition unit 10 is a module that acquires various information, including propagation path information and terminal information, from an AMR, which is a mobile object that moves within a predetermined geographical area, such as within a factory. The acquisition unit 10 acquires various information from the AMR via a base station installed within the factory or the like. The base station is a radio device that forms a wireless communication area that includes a predetermined geographical area, such as within a factory, through which the AMR moves. The base station performs wireless communication with the AMR within the wireless communication area, more specifically, with the radio device installed in the AMR. The information processing device 1 and the base station may be connected via a wired or wireless connection. In other words, the concept of the acquisition unit 10 encompasses a module that acquires various information via a wired connection and a module that acquires various information via a wireless connection.

[0014] Propagation path information is information that serves as a means of understanding the status of the radio wave propagation path between the base station and the AMR at the location where the AMR is located within a factory, for example. Details of propagation path information will be described later. Terminal information is, for example, scan data from an LRF (Laser Range Finder) installed on the AMR, and / or data on the AMR's movement speed and direction.

[0015] The processing unit 20 processes the information acquired by the acquisition unit 10. The processing unit 20 is one or more electronic circuits including a control unit and an arithmetic unit. The electronic circuits are realized by analog or digital circuits, etc. For example, a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), an ASIC, an FPGA, a system-on-chip (SoC), or a combination thereof is possible. Furthermore, at least some of the units in the processing unit 20 may be executed by these electronic circuits using software or programs.

[0016] The radio wave map generating unit 22, the propagation path status grasping unit 23, and the radio wave map interpolating unit 24 will be described in detail later, but first, an overview of each unit in the processing unit 22 will be described.

[0017] The control unit 21 stores the various types of information acquired by the acquisition unit 10 in the storage unit 30, and also reads this information from the storage unit 30 and transfers it to the radio wave map generation unit 22 and the propagation path status assessment unit 23. The storage unit 30 is a volatile storage medium such as a DRAM (Dynamic RAM [Random Access Memory]), or a non-volatile storage medium such as an HDD (Hard Disk Drive). In the former case, the storage unit 30 functions as a buffer, and in the latter case, the storage unit 30 functions as storage.

[0018] The radio wave map generation unit 22 generates a radio wave map from propagation path information, terminal information (the current location of the AMR ascertained from the terminal information), and map information. The radio wave map is information that indicates, for example, the distribution of received power within a factory. In other words, it is information in which data related to received power at each point within a factory is mapped. Details of the radio wave map will be described later. Map information is, for example, information related to the layout within a factory, and is information generated from LRF scan data, which is one type of terminal information. Details of the map information will also be described later.

[0019] The propagation path status grasping unit 23 grasps (determines) the status of the propagation path from the propagation path information. The radio wave map interpolation unit 24 interpolates missing parts on the radio wave map generated by the radio wave map generation unit 22 based on the status of the propagation path. More specifically, the radio wave map interpolation unit 24 appropriately determines a method for interpolating the radio wave map depending on the status of the propagation path. In addition, the radio wave map interpolation unit 24 calculates the reliability of the interpolated data.

[0020] The output unit 40 is a module that outputs various information including the radio wave map generated by the radio wave map generation unit 22 and having missing portions interpolated by the radio wave map interpolation unit 24, and reliability information indicating the reliability calculated by the radio wave map interpolation unit 24. The output of the various information can be performed via a wired connection or wirelessly. In other words, the concept of the output unit 40 encompasses a module that outputs various information via a wired connection and a module that acquires various information via wireless connections.

[0021] In the information processing device 1 configured as described above, when missing data in the radio wave map is interpolated, the interpolation method is changed depending on the propagation path conditions, thereby enabling a more accurate radio wave map to be reproduced. Furthermore, since accurate interpolation is difficult in an environment with a lot of multipath, by outputting reliability information in association with the radio wave map, it is possible to obtain the effect that the information can be referenced in AMR route selection performed using the radio wave map.

[0022] Next, an application example of the information processing device 1 according to the embodiment will be described. Fig. 2 is a diagram showing an application example of the information processing device 1 according to the embodiment.

[0023] Consider, for example, an automated guided robot (AMR) moving around a factory. Simple control is sufficient for linear movement within a limited range along a pathway. However, more sophisticated control is required for complex movements, such as turning around corners or avoiding obstacles. Wired control of this type of control presents challenges, such as limited control within the reach of the wire, loss of control due to wire breaks, and tangled wires. These issues become particularly pronounced when controlling multiple robots. Wireless control, on the other hand, solves these problems. Wireless control can be achieved, for example, via wireless LAN or local 5G. Robots can be broadly divided into two types: those that operate autonomously and those that operate based on external commands. While the former type is useful for each robot to determine its own situation, the cost of each robot is high, which can have a significant impact when using multiple robots. In contrast, the latter type can reduce total costs by consolidating functions into a device that issues commands from an external source. Furthermore, the ability to obtain information about each robot at a glance is convenient for management purposes.

[0024] Therefore, a system in which the MEC server 100 centrally controls the AMR 200 via the base station 110 is assumed here. Also, it is assumed that the information processing device 1 of the embodiment has its functions incorporated into the MEC server 100 as a received power data processing device. A cloud system can also be assumed as a system for centrally controlling the AMR 200. In this case, the functions of the information processing device 1 are incorporated into a server on the cloud.

[0025] Next, a radio wave map and wireless control of the AMR 200 will be described. Hereinafter, the MEC server 100 and the base station 110 may be collectively referred to as the base station 110 side.

[0026] As an example, consider using Local 5G to control a terminal (AMR200) on the base station 110 side. More specifically, control is performed by the MEC server 100 to operate the AMR200. To operate the AMR200 along an appropriate route, the AMR200 side acquires the received power of signals (downlink [line]) from the base station 110 at each location. The MEC server 100 associates map information created by moving the AMR200 around with the estimated location and received power to create a heat map of the received power at each location, i.e., a radio wave map. The map information, estimated location, and received power information are transmitted from the AMR200 to the base station 110 via the uplink. The MEC server 100 selects an appropriate route for the AMR200 based on the information in the radio wave map. For example, it is possible to control the AMR200 not to pass through locations with weak received power because there is a possibility that the AMR200 may become uncontrollable.

[0027] Next, the advance preparation of map information and radio wave maps will be described. If the environment in which the AMR 200 moves is relatively static, it is sufficient to store fixed map information. However, in an environment where the location of objects changes over time, such as a factory, the map information needs to be updated as appropriate, and the situation is different. Therefore, a map is first created. Under the control of the MEC server 100, the AMR 200 moves throughout the entire area where it may travel during transportation. The AMR 200 determines the distance to walls and obstacles by measuring the time of flight (TOF) using an LRF or the like. Then, the LRF scan data, speed, and (wheel) direction are sent to the base station 110 via the uplink, and the map and the position of the AMR 200 are determined. Next, based on the map information, the AMR 200 again moves throughout the entire area under the control of the MEC server 100, and a radio wave map is created. The base station 110 broadcasts a synchronization signal, and the AMR 200 receives this synchronization signal and returns received power information, such as SSS-RSRP (Secondary Synchronization Signal Reference Signal Received Power) and PSS-RSRP (Primary Synchronization Signal Reference Signal Received Power), to the base station 110 via uplink. At this time, the AMR 200 also transmits LRF scan data, speed, and (wheel) direction to the base station 110, just as it did when creating the map. This has the significance of updating the map from the time of map creation and of linking the received power with the map / self-location. With regard to the latter, even if the received power can be measured, it is meaningless as a radio wave map unless its location can be identified. Note that in the above procedure, map creation and radio wave map creation are separate processes, but they may be performed simultaneously from the beginning.

[0028] Next, the update of map information and radio wave maps will be explained. Based on the radio wave map calculated in the advance preparation described above, the AMR200 selects a specific route and begins actual operation. In a factory, for example, one example would be transporting cargo. During actual operation, as described above, the received power and map / self-location are measured and information is updated. The MEC server 100 may individually store radio wave maps that differ over time, may store only the latest radio wave map, or may merge the latest radio wave map with the most recent radio wave map and store it. The MEC server 100 may determine whether to update based on reliability information. Furthermore, when multiple AMR200s are in operation, the radio wave maps for each may be merged and saved.

[0029] Next, the missing data in the radio wave map will be described. When the MEC server 100 generates a radio wave map, there may be missing received power data in some locations. Consider this case using Local 5G as an example. The base station 110 transmits a synchronization signal continuously for 5 ms, waits a 20 ms interval, and then transmits it again for 5 ms. In the case of a frequency of 3 to 6 GHz and a subcarrier spacing of 15 kHz, eight SS / PBCH (Synchronization Signal / Physical Broadcast Channel) blocks are transmitted within 5 ms. Since each SS / PBCH contains one PSS and one SSS, the AMR 200 can obtain eight pieces of PSS-RSRP and SSS-RSRP information within 5 ms. Here, consider the case where a radio wave map is created using 5-cm square pixels. When the AMR travels at 1 m / s, it takes 50 ms to travel one pixel. In other words, 16 pieces of PSS-RSRP and SSS-RSRP information are obtained per pixel, which is sufficient for obtaining received power information. However, creating a radio wave map is meaningless unless it is associated with locations on the map. When LRF scan data, received power information, and self-location information are sent over the uplink, communication delays due to the large amount of data and processing delays in the MEC server 100 can delay the association of these data, potentially resulting in pixels without information in the radio wave map. Furthermore, uplink resources must be allocated in the previous downlink, and depending on the allocation timing, data may not be transmitted over the uplink immediately upon generation, resulting in delays.

[0030] Next, the spatial interpolation of the radio wave map and the propagation paths will be explained. Figure 3 shows an example of a radio wave map obtained by mapping the received power at each point using the Friis propagation formula, assuming a frequency of 4.8 GHz. The Friis propagation formula simulates a channel in which the received power decreases monotonically with distance and is dominated by direct waves. While it would be ideal to obtain the received power for all points as shown in Figure 3, as mentioned above, there may be gaps in the radio wave map, as shown in Figure 4, for example. However, in this case, the received power decreases monotonically, so interpolation is considered easy.

[0031] On the other hand, Figure 5 shows the received power obtained using the Friis propagation formula, with a random variation of 0 to 6 dB. When reflected waves are present, the strength varies depending on the phase relationship between the direct wave and the reflected wave at the receiving point, and the phase relationship between the reflected waves themselves, resulting in a non-monotonically decreasing received power with distance. In this state, if gaps appear in the radio wave map, as shown in Figure 6, interpolation becomes more difficult. This suggests the need to change the interpolation method depending on the propagation path conditions. Note that the radio wave maps in Figures 3 to 6 are considered two-dimensionally on the xy plane, but they can also be considered three-dimensionally by adding the z-axis, or they can be sliced along the z-axis to consider two-dimensional radio wave maps on the xy plane for each height.

[0032] The spatial interpolation of radio wave maps and propagation paths will now be further explained. In cellular communications, when an AMR200 moves around at a speed of 1 m / s, received power is acquired frequently, as mentioned above. If uplink communications are performed without delay, it is possible to obtain the 5 cm square radio wave map mentioned above. Then, based on the received power data acquired in detail at each pixel, interpolation can be performed with a certain degree of accuracy in environments dominated by direct waves. However, this interpolation approach is not suitable when there is a lot of multipath or when fine spatial resolution is not required.

[0033] There are three theories of radio wave propagation: [1] instantaneous fluctuations (fading), [2] short-term fluctuations (shadowing), and [3] long-term fluctuations (propagation distance characteristics). [1] Instantaneous fluctuations (fading) look at intervals of up to a few wavelengths with a resolution of less than one wavelength. This allows for the spatial distribution of standing waves caused by arriving multiple waves to be understood. [2] Short-term fluctuations (shadowing) look at intervals of up to about 100 meters with a resolution of 1 to 10 meters. In a cellular environment, the degree of obstruction from buildings and other obstacles changes as you move, and this effect is apparent depending on the location. [3] Long-term fluctuations (propagation distance characteristics) look at intervals on the order of kilometers with a resolution of 10 to 100 meters. For example, in a macrocell, it is possible to understand macro trends, such as attenuation by the third or fourth power.

[0034] Therefore, the information processing device 1 of the embodiment appropriately selects a method of interpolating the radio wave map based on the state of the propagation path. That is, the information processing device 1 adaptively uses a method of tracking instantaneous fluctuations (first fluctuations), a method of tracking short-term fluctuations (second fluctuations), and a method of tracking long-term fluctuations (third fluctuations).

[0035] For example, when there is a lot of multipath or when fine spatial resolution is not required, the information processing device 1 assumes [2] short-term fluctuation (shadowing) or [3] long-term fluctuation (propagation distance characteristics) rather than [1] instantaneous fluctuation (fading) when interpolating the radio wave map. There is a relationship between the pixel resolution of the radio wave map and [1] instantaneous fluctuation (fading), [2] short-term fluctuation (shadowing), and [3] long-term fluctuation (propagation distance characteristics). When assuming [2] short-term fluctuation (shadowing) or [3] long-term fluctuation (propagation distance characteristics), the information processing device 1 changes the pixel resolution of the radio wave map from a fine resolution (e.g., 5 cm) such as (A) to a coarse resolution (e.g., 1 to 10 m or 10 to 100 m) such as (B), as shown in FIG. 7. The resolution may also be changed depending on the location.

[0036] The information processing device 1 may change the resolution according to requirements, such as the convenience of using the radio wave map for route selection, whether or not the area is prone to collision with an obstacle, etc. If it is necessary to track even instantaneous fluctuations according to requirements and the influence of multipath is significant, the information processing device 1 may perform interpolation in a state where the influence of multipath is suppressed by using spatial diversity technology using an array antenna or averaging the received power in the frequency direction or the time direction, or may also use an index of the reliability of the interpolated value.

[0037] Next, the propagation path information will be described. The information processing device 1 uses, as propagation path information, received power measured on the AMR 200 side using a synchronization signal or a reference signal from the base station 110. As an index, RSRP (Reference Signal Received Power), RSSI (Received Signal Strength Indicator), etc. For example, in 5G, a synchronization signal is broadcast from the base station 110, and it is possible for the terminal (AMR 200) side to acquire the received power of the SSS or PSS of the synchronization signal.

[0038] In addition, in 5G, multiple reference signals are provided, such as a reference signal CSI-RS (Channel State Information Reference Signal) for channel information estimation and a reference signal DMRS (Demodulation Reference Signal) for demodulation, and the information processing device 1 may use the received power for each frequency and the impulse response of the propagation path as propagation path information.

[0039] The base station 110, more specifically, the MEC server 100, acquires information on the received power measured on the AMR 200 side via the uplink. The MEC server 100 (information processing device 1) can use the information on the received power at each point and time acquired in this way as one of the materials for understanding the state of the propagation path.

[0040] Next, the current position and map information will be described. The MEC server 100 receives the LRF scan data, movement speed, and direction information of the AMR 200 to determine the current location and map information. Regarding the map information, for example, in the case of a factory, a known initial layout may be referenced and sequentially updated. Furthermore, as an example, if the AMR 200 is equipped with two LRFs, one for viewing the upper part in the vertical direction and the other for viewing the lower part, by acquiring the information from these, the MEC server 100 can determine whether cargo or obstacles are piled up in the factory. The propagation path status determination unit 23 of the information processing device 1 has difficulty determining the cause of fluctuations in the propagation path information alone. However, by linking map information with the propagation path information and making a comprehensive determination, the propagation path status can be more accurately determined.

[0041] If the propagation path information changes due to the accumulation of luggage or obstacles, the reliability index is not lowered, and the data used for interpolation is divided at that point. Conversely, if the propagation path information changes even though there is no accumulation of luggage or obstacles, the reliability index for that point can be lowered and the received power can be interpolated.

[0042] Based on the above, each unit of the processing unit 20 of the information processing device 1 will be described in detail. First, the radio wave map generating unit 22 will be described.

[0043] The radio wave map generator 22 generates a map that associates the position with the received power for the range in which the AMR 200 moves around on the map.

[0044] Regarding the position, the size of one pixel may be determined and displayed as coordinates from a reference point, or the distance itself may be displayed. The resolution may also be changed by partially changing the size of one pixel. The size of one pixel may also be determined based on the smallest unit of an obstacle that can be identified. The received power may be replaced with throughput or bit error rate.

[0045] By generating a radio wave map in this manner, the radio wave map generation unit 22 can utilize the map to select a route for the AMR 200 with good communication conditions between the base station 110 and the AMR 200, which is performed by the MEC server 100, thereby realizing stable operation of the AMR 200.

[0046] Next, the propagation path status grasping unit 23 will be described. FIG. 8 is a diagram illustrating an example of how the received power is acquired in the information processing device 1 of the embodiment.

[0047] As shown in Fig. 8, the AMR 200 acquires the first received power from a synchronization signal / reference signal from the base station side 110 (1). The AMR 200 stores the information in an uplink packet and sends it to the base station 110 side (2). This allows the base station 110 side to grasp the received power (first received power) at each point (3). In addition, since a reference signal is also added to the uplink packet at this time, the base station side 110 can acquire the second received power using this reference signal (4).

[0048] In radio wave propagation, due to duality, the first received power and the second received power are theoretically equal. Therefore, if there is a large difference between the first received power and the second received power, the propagation path status ascertaining unit 23 can predict that there has been some kind of propagation fluctuation, and can ascertain the time fluctuation.

[0049] Here, because a difference between the first received power and the second received power occurs due to movement of the AMR 200, it is preferable to measure the received power of a reference signal, which has a smaller time difference between when the first received power is acquired and when the second received power is acquired, rather than a broadcast synchronization signal, in the AMR 200. For example, by acquiring the RSRP of the reference signal CSI-RS in the downlink and the RSRP of the reference signal SRS (Sounding Reference Signal) in the uplink, it is possible to more appropriately grasp time fluctuations.

[0050] As another method for grasping time variations, the propagation path status grasping unit 23 may acquire multiple first received powers for the minimum resolution of the radio wave map and grasp the difference between them. As described above, if the radio wave map is created using 5 cm square pixels and the AMR 200 travels at 1 m / s, it takes 50 ms to travel one pixel. For example, one method is to grasp the power difference between synchronization signals acquired multiple times during that 50 ms. In this case, the speed of the AMR 200 may be determined conversely, taking into account the interval between synchronization signals and the size of one pixel. Note that when grasping time variations with priority, the AMR 200 may be moved at a constant speed, temporarily stopping the LRF scan data and position information sent via the uplink, and giving priority to instantaneously sending received power data via the uplink.

[0051] In this way, by obtaining the received power by oversampling one pixel of the radio wave map and observing the fluctuations, the propagation path status ascertaining unit 23 can ascertain whether the propagation path has large time fluctuations or not.

[0052] In addition, in radio wave propagation, there is an index called the Rice factor, which represents the ratio of the power of the direct wave to the reflected wave. When the reflected wave strength is weak, the Rice factor becomes large, and when the reflected wave strength is strong, the Rice factor becomes small. For example, the Rice factor for a given environment can be derived by comparing the received power of each subcarrier of OFDM (Orthogonal Frequency Division Multiplexing) acquired multiple times over time with the received power of a propagation path theoretically derived by varying multiple Rice factors.

[0053] Furthermore, when receiving signals using an array antenna with multiple elements, spatial correlation is an index that indicates the similarity of the signals entering each element. A high spatial correlation indicates a strong influence of the direct wave, while a low correlation indicates a weak influence of the direct wave.

[0054] In this way, the degree of multiple waves (multipath) can be grasped using the Rice factor and spatial correlation. When the influence of direct waves is strong, the received power tends to decrease monotonically with distance. When the influence of reflected waves is strong, the received power tends to fluctuate with distance due to phase reinforcement and cancellation. By grasping the propagation path status in this way, the propagation path status grasping unit 23 can change the interpolation method based on the grasped status. Note that, with regard to the classification of channels dominated by direct waves and channels dominated by reflected waves, a threshold may be set at a Rice factor of X dB or more or less, and a threshold may also be set at a spatial correlation of Y or more or less.

[0055] In addition, in 5G, demodulation reference signals (DMRS) are arranged in the frequency direction. DMRS can be used to calculate the received power versus frequency and the impulse response of the propagation path, making it possible to grasp the frequency characteristics. In the case of wideband transmission, if the frequency characteristics of the received power are flat, the influence of direct waves is strong, and if there is large fluctuation, the influence of multiple waves is strong. If the propagation path status grasping unit 23 grasps this, the radio wave map interpolation unit 24 can change the interpolation method depending on the propagation path status.

[0056] Figure 9 shows an example of measured values of a radio wave map in an office environment. Here, a 5 GHz band wireless LAN access point (AP) 110A is installed at a height of 1.2 m, and a terminal (AMR200) receiving a beacon is moved linearly at a constant speed of 0.1 m / s along a path at a height of 0.2 m. Note that the AP 110A side is equipped with a single antenna, while the AMR 200 side is equipped with multiple antennas and diversity is applied. For all three paths, the received power tends to decrease the farther away from the AP 110A.

[0057] Figures 10 to 12 plot the relationship between distance from the AP and RSSI for the three routes (Y=0, 3, and 6) in Figure 9. The distance from AP 110A ranges from 4 to 15 m. The received power is theoretically proportional to the x-th power of the distance, so the graphs are semi-logarithmic. The regression line is also shown. As shown in Figure 9, for Y=3 in Figure 11 and Y=6 in Figure 12, both reception points are within line-of-sight, so the signal power falls within a range of approximately 5 dB from the regression line and tends to decrease monotonically with distance. Furthermore, the slope of the regression line follows a 1.2-power law for Y=3 and a 0.8-power law for Y=6. However, for Y=0, which includes line-of-sight and non-line-of-sight, the line-of-sight / non-line-of-sight boundary shown in Figure 9 changes, so the trend changes significantly, and the data may deviate by approximately 10 dB from the regression line. Therefore, it is safe to assume that the multiplier of radio wave propagation attenuation changes at the boundary of an obstacle.

[0058] In this way, the propagation path status grasping unit 23 can determine that there is an obstacle at a point where the attenuation multiplier changes significantly, and if there is a missing data, the radio wave map interpolation unit 24 can change the interpolation method based on that point.

[0059] Next, the radio wave map interpolation unit 24 will be described. The radio wave map interpolation unit 24 interpolates gaps in the radio wave map according to the propagation path conditions grasped by the propagation path condition grasping unit 23. First, the presence or absence of time fluctuations is confirmed. As described above, the presence or absence of time fluctuations can be confirmed by the difference in received power between the uplink and downlink of the propagation path condition grasping unit 23 and the difference in oversampled power data. If there are time fluctuations, the radio wave map interpolation unit 24 suspects a change in layout due to an obstacle or the like, and if there are changes in two or more LRF scan data or propagation multipliers as described above, it separates the data used for interpolation at the expected obstacle as a boundary. If there are no changes in the LRF scan data or propagation multipliers, the radio wave map interpolation unit 24 performs interpolation but reduces the reliability of the interpolated data.

[0060] Furthermore, if the propagation path status assessment unit 23 determines that there is little multipath interference, the received power monotonically decreases with distance. Therefore, the radio wave map interpolation unit 24 interpolates the radio wave map data on the order of wavelength, i.e., assuming instantaneous fluctuations (fading). In this case, the radio wave map interpolation unit 24 may perform linear interpolation using a semi-logarithmic horizontal axis as shown in FIG. 10, or may perform interpolation based on a regression line drawn from the acquired received power data. In addition to interpolation, the radio wave map interpolation unit 24 may also perform extrapolation using the regression line of the acquired received power data for locations where there is similarly little multipath interference. As the distance between the base station 110 and the AMR 200 increases, the change in the distance between the base station 110 and the AMR 200 relative to the movement of the AMR 200 decreases. Taking advantage of this property, the received power value of a neighboring pixel may be copied. Instead of using all measured data for interpolation, data may be divided into data used for interpolation and data used to verify its accuracy. The radio wave map interpolation unit 24 may exclude plot points that deviate significantly from the regression line of the acquired received power data, for example, plot points that deviate by 20 dB, as outliers from the data used for interpolation. The radio wave map interpolation unit 24 may increase the interpolation resolution at points where the received power is close to the minimum receiving sensitivity, or may perform extrapolation at points below the minimum receiving sensitivity. Furthermore, when there is little time fluctuation and little multiplexing, the radio wave map interpolation unit 24 increases the reliability of the interpolated data.

[0061] Furthermore, when the propagation path status assessment unit 23 determines that there are many multiplex waves, the radio wave map interpolation unit 24 interpolates the radio wave map data assuming short-term fluctuations (shadowing) longer than the order of wavelength or even longer-term fluctuations (propagation distance characteristics) because the received power fluctuates significantly over distance. In this case, the radio wave map interpolation unit 24 reduces the spatial resolution of the radio wave map, as described with reference to FIG. 7 . Linear interpolation may be performed using the received power values of adjacent radio wave maps, or the received power itself may be interpolated using techniques such as Kriging, graph theory, or compressed sensing at the same resolution as when there are few multiplex waves, and then the spatial resolution may be reduced and averaged. Furthermore, even if there is little time fluctuation, when there are many multiplex waves, the radio wave map interpolation unit 24 reduces the reliability of the interpolated data.

[0062] On the other hand, if spatial diversity using multiple antennas can be utilized on the base station 110 side or the AMR200 side, or if the received signal can be sufficiently averaged in frequency and time by adjusting the bandwidth of the frequency used or the speed of the AMR200, the effects of multiple waves can be suppressed, so the radio wave map interpolation unit 24 may perform linear interpolation while maintaining fine resolution, or may increase the reliability of the interpolated data.

[0063] The radio wave map interpolation unit 24 outputs a reliability associated with each pixel of the radio wave map. The radio wave map interpolation unit 24 may output only points with low reliability. By mapping the reliability in this manner when interpolating the radio wave map, it is possible to improve the convenience of the AMR200 when selecting a route. When the difference between the first received power and the second received power is large, the radio wave map interpolation unit 24 may lower the reliability of the pixel of the radio wave map interpolated using that data, assuming that the influence of time fluctuation is large. Furthermore, when interpolating using data from a reception point with a high degree of multiple waves, the radio wave map interpolation unit 24 may also lower the reliability of the pixel.

[0064] The radio wave map interpolation unit 24 also outputs one-dimensional, two-dimensional, or three-dimensional coordinates divided into pixels and the received power corresponding to the coordinates. The radio wave map interpolation unit 24 may also output the correspondence between the distance in the x-direction, y-direction, and z-direction from the set origin and the received power.

[0065] FIG. 13 shows the result of applying interpolation to the path [2] (Y=3) in FIG. The experimental data was acquired at 1 cm intervals on the AMR 200 side. The circles indicated by symbol a1 represent these actual measured values (data). As an example, assume that the base station side was only able to acquire data at 20 cm intervals due to delays when sending on the uplink. The star marks indicated by symbol a2 represent data acquired on the base station 110 side. Then, the data interpolated by the information processing device 1 from this 20 cm interval data was compared with the values of the actual measured data at 1 cm intervals. The triangle marks indicated by symbol a3 represent this interpolated data. Note that this environment is line-of-sight and spatial diversity is also applied, so the interpolation is performed by linear interpolation.

[0066] FIG. 14 is a diagram showing the results in the form of a cumulative distribution function (CDF). In radio wave propagation, 3 dB is considered an error level, and it can be seen from Figure 14 that nearly 90% of the data is within an error of 3 dB. This confirms that even simple linear interpolation can provide a certain degree of accuracy depending on the propagation path conditions.

[0067] 15 is a flowchart showing the operation procedure of the information processing device 1 according to the embodiment. This procedure may be executed by a program in the electronic circuit described above. The information processing device 1 first creates a radio wave map (S101). The information processing device 1 grasps the state of the propagation path between the base station 110 and the AMR 200 (S102). The information processing device 1 interpolates the radio wave map based on the state of the propagation path (S103).

[0068] FIG. 16 is a flowchart showing the procedure for selectively using the interpolation method in the radio wave map interpolation in S103 of FIG.

[0069] The information processing device 1 first determines whether the environment is rich in multiple waves (S201). If the environment is rich in multiple waves (S201: NO), the information processing device 1 performs interpolation of the radio wave map assuming instantaneous fluctuations (fading) (S202). In other words, the interpolation is performed at a fine granularity.

[0070] On the other hand, if the environment is one with many multiplex waves (S201: YES), the information processing device 1 determines whether the base station 110 or the AMR 200 is applying diversity with multiple antennas (S203). If diversity is not being applied (S203: NO), the information processing device 1 performs interpolation of the radio wave map assuming short-term fluctuations (shadowing) or long-term fluctuations (propagation distance characteristics) (S04). In other words, the interpolation is performed at a coarse granularity. As an alternative method when diversity is not being applied, the information processing device 1 may perform interpolation using techniques such as Kriging, graph theory, or compressed sensing, and then reduce the spatial resolution and perform averaging. In this case, in an environment with many multiplex waves and in a situation where diversity is not being applied, interpolation is performed at a fine granularity.

[0071] When diversity is applied (S203: YES), the information processing device 1 performs interpolation of the radio wave map assuming instantaneous fluctuations (fading) even in an environment with many multiple waves (S202). In other words, interpolation is performed at a fine granularity.

[0072] As described above, the information processing device 1 according to the embodiment can reproduce a more accurate radio wave map by changing the interpolation method of the radio wave map according to the propagation path conditions. In other words, the information processing device 1 according to the embodiment can appropriately interpolate the radio wave map.

[0073] (Variation) FIG. 17 is a diagram illustrating a modified example of the information processing device 1 according to the embodiment. In the above description, an example has been shown in which the information processing device 1 is realized as a received power data processing device that generates a radio wave map and interpolates the radio wave map according to the state of the propagation path. The function of the information processing device 1 as a received power data processing device is incorporated, for example, into an MEC server 100 that centrally manages the AMR 200, and the MEC server 100 selects a route for the AMR 200 based on the radio wave map and reliability information output from the information processing device 1.

[0074] 17, the processing unit 20 further includes a route generation unit 25. The route generation unit 25 executes route selection (route generation) for the AMR 200 based on the radio wave map and reliability information output from the radio wave map interpolation unit 24.

[0075] That is, the information processing device 1 of the one modified example is realized as a route generation device that executes route generation in addition to receiving power data processing. The MEC server 100 incorporating the functions of the information processing device 1 as a route generation device can obtain route information from the information processing device 1 instead of radio wave maps and reliability information.

[0076] Alternatively, a modified example can be considered in which the radio wave map generating unit 22 is deleted from the processing unit 20 of the information processing device 1 of the embodiment. In other words, the information processing device 1 may be realized as a received power data processing device that does not have the function of generating a radio wave map, but only has the function of interpolating the radio wave map depending on the state of the propagation path.

[0077] In these modified examples, the information processing device 1 also has the effect of being able to appropriately interpolate the radio wave map.

[0078] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0079] 1...information processing device, 10...acquisition unit, 20...processing unit, 21...control unit, 22...radio wave map generation unit, 23...propagation path status grasping unit, 24...radio wave map interpolation unit, 25...route generation unit, 30...storage unit, 40...output unit, 100...MEC server, 110...base station, 200...AMR

Claims

1. a processing unit that generates data for missing portions on a radio wave map on which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on a state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device that forms a wireless communication area including the predetermined geographical range; the processing unit determines the state of the propagation path based on a difference between a first reception power measured at the first radio device side and a second reception power measured at the second radio device side. Information processing device.

2. A processing unit is provided which generates data for missing parts on a radio wave map onto which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on the state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device forming a wireless communication area including the predetermined geographical range; the processing unit determines the state of the propagation path based on a change in an attenuation multiplier of received power with respect to a distance between the first radio device and the second radio device. Information processing device.

3. A processing unit is provided which generates data for missing parts on a radio wave map onto which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on the state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device forming a wireless communication area including the predetermined geographical range; the processing unit generates data of the missing portion on the radio wave map based on a first fluctuation in the received power when the received power of the direct wave is greater than the received power of the reflected wave. Information processing device.

4. A radio wave map is provided which generates data for missing parts on a radio wave map onto which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on the state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device which forms a wireless communication area including the predetermined geographical range; when the received power of the reflected wave is greater than the received power of the direct wave, the processing unit generates data of the missing portion on the radio wave map based on a second fluctuation of the received power or a third fluctuation in a section longer than the second fluctuation. Information processing device.

5. A radio wave radio communication system comprising: a processing unit that generates data for missing portions on a radio wave map on which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on the state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device forming a wireless communication area including the predetermined geographical range; the processing unit outputs the reliability of data of at least the generated missing portion in the radio wave map. Information processing device.

6. A radio wave radio communication system comprising: a processing unit that generates data for missing portions on a radio wave map on which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on the state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device that forms a wireless communication area including the predetermined geographical range; the processing unit generates a route within the predetermined geographical range that the first radio device should travel based on the radio wave map obtained by generating and interpolating data for the missing portion; an output unit that outputs the route generated by the processing unit to the first radio device; Information processing device.

7. a first radio device that moves within a predetermined geographical range; a second radio unit that forms a wireless communication area including the predetermined geographical range; The information processing device according to claim 1 ; A system comprising:

8. generating data for missing portions on a radio wave map on which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on a state of a propagation path between a first radio device moving within the predetermined geographical range and a second radio device forming a wireless communication area including the predetermined geographical range; determining the state of the propagation path based on a change in an attenuation multiplier of the received power with respect to the distance between the first radio device and the second radio device; method.

9. In the information processing device, generating data for missing portions on a radio wave map on which data relating to the received power of radio signals at each point in a predetermined geographical range is mapped, based on the state of a propagation path, including time fluctuations, between a first radio device moving within the predetermined geographical range and a second radio device forming a wireless communication area including the predetermined geographical range; determining the state of the propagation path based on a change in an attenuation multiplier of received power with respect to the distance between the first radio device and the second radio device; program.

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