Wireless signal measurement system

Abstract

To provide a wireless signal measurement system that can efficiently perform measurements on wireless stations present in a search area.SOLUTION: A wireless signal measurement system according to an embodiment of the present invention includes a wireless signal measurement device (3) for performing measurements on a plurality of WRAN wireless stations of a WRAN system to be observed. The wireless signal measurement device (3) receives wireless signals from WRAN wireless stations (e.g., WRAN mobile station 1 (2-1), WRAN mobile station 3 (2-3)) within a search area without being connected to the WRAN system, obtains wireless station identification information for identifying the WRAN wireless station that has sent the wireless signal on the basis of the wireless signal, and calculates the number of the WRAN wireless stations present within the search area.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wireless signal measurement system that performs measurements on a plurality of wireless stations in a wireless system that is an object of observation. [Background technology]

[0002] In a wireless communication system, in order to grasp the influence of interference from wireless signals transmitted by wireless stations and to avoid interference, it is important to grasp the presence of wireless stations in the surrounding environment. For example, when connecting a new wireless station to the same user's system, it is important to grasp in advance whether there are connectable wireless stations within the range of radio waves and how many connectable wireless stations exist. It is also important to grasp the presence of wireless stations of other users in order to avoid interference.

[0003] In recent years, research has been conducted on a technology that not only confirms the presence of wireless stations, but also analyzes received wireless signals and estimates the location of wireless stations (Non-Patent Document 1). Also, an invention has been proposed that acquires wireless station identification information from downstream signals, measures a delay profile, and estimates the location of wireless stations using the delay profile (Patent Document 1). Since some wireless communication systems allow mobile communication, it is possible to use the information to help manage wireless communication operations by continuously monitoring the presence and number of wireless stations over time.

[0004] Before explaining this proposal, we will explain the wireless communication system that is the subject of this proposal. The standard ARIB STD-T103 established by the Association of Radio Industries and Businesses (ARIB) specifies the physical layer and media access control layer of broadband mobile communication between portable base stations and mobile stations among the radio equipment of radio stations that perform 200MHz band broadband mobile wireless communication. Since a portable base station is a land mobile station under the Radio Law, it can be flexibly installed and operated wherever necessary, and it is possible to transmit images of the site to the headquarters, etc., mainly in emergency areas such as disaster sites and crime sites. A wireless communication system that complies with ARIB STD-T103 basically consists of one portable base station and one or multiple mobile stations, and when it consists of multiple mobile stations, a star-shaped network topology is formed.

[0005] On the other hand, ARIB STD-T119 specifies the physical layer, media access control layer, and radio network control layer of portable radio equipment among the radio equipment of radio stations performing 200 MHz band wideband mobile radio communication specified by the above ARIB STD-T103, and in particular specifies the multi-stage relay function, which is one of the assumed operation forms. A WRAN (Wireless Regional Area Network) system, which is a radio communication system conforming to ARIB STD-T119, is equipped with a radio network control scheduler, a portable base station, and a mobile station, and when multiple mobile stations are included, a tree-type (broadly speaking, including serial connection and star type) network topology is formed. In the following, a portable base station of a WRAN system is referred to as a "WRAN base station," and a mobile station of a WRAN system is referred to as a "WRAN mobile station." In addition, a WRAN base station and a WRAN mobile station may be collectively referred to as a "WRAN radio station," or simply as a "radio station."

[0006] FIG. 7 shows a schematic diagram of an operation image of a conventional WRAN system. The WRAN system shown in FIG. 7 includes a WRAN base station (1), a WRAN mobile station A (2-1), a WRAN mobile station B (2-2), and a WRAN mobile station C (2-3). The WRAN base station (1) is wirelessly connected to the WRAN mobile station A (2-1) and the WRAN mobile station B (2-2). The WRAN mobile station B (2-2) is wirelessly connected to the WRAN mobile station C (2-3), forming a multi-stage relay configuration. The WRAN mobile stations A (2-1) to C (2-3) are mounted on, for example, a moving vehicle, and can perform wireless communication while moving.

[0007] In a wireless connection, the wireless station closer to the WRAN base station is called the "upper station," and the wireless station farther away is called the "lower station." Additionally, a wireless signal from a higher station to a lower station is called a "downstream signal," and a wireless signal from a lower station to a higher station is called an "upstream signal." When performing multi-stage relaying, a WRAN mobile station alternates between transmitting a downstream signal and receiving an upstream signal as a higher station, and transmitting an upstream signal and receiving a downstream signal as a lower station.

[0008] Figure 8 shows an example of the transmission and reception timing of each wireless station in the network topology of the WRAN system in Figure 7. In Figure 8, the horizontal axis represents time, the vertical axis represents each wireless station in the WRAN system, and the arrows in the figure represent the direction of wireless transmission and reception between wireless stations. Also, "DL" in the figure represents downstream (downlink) transmission / reception, and "UL" represents upstream (uplink) transmission / reception.

[0009] In the WRAN system, the wireless band is allocated on a wireless frame basis. In the example of FIG. 8, for example, in frame numbers [1] to [3], the WRAN base station (1) and the WRAN mobile station A (2-1) communicate with each other, and in frame numbers [4] to [6], the WRAN mobile station A (2-1) and the WRAN mobile station C (2-3) communicate with each other. The WRAN mobile station B (2-2) is not connected to a lower station, but transmits a downlink signal in frame numbers

[13] to

[15] . Similarly, the WRAN mobile station C (2-3) is not connected to a lower station, but transmits a downlink signal in frame numbers [7] to [9]. This downlink transmission includes a signal (entry signal) required to add a new lower station to the WRAN system. As shown in FIG. 8, each wireless station repeats transmission and reception at a fixed cycle, and the constant cycle of transmission and reception of the entire WRAN system is called a "scheduling pattern." [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2022-135813 A [Non-patent literature]

[0011] [Non-Patent Document 1] IEICE Technical Report, vol.120, No.138, SRW2020-15, pp.31-36, August 2020. Summary of the Invention [Problem to be solved by the invention]

[0012] Problems that arise when checking the presence of a radio station in a conventional WRAN system will be described. First, an operation flowchart of a conventional WRAN radio station shown in FIG. 9 will be used as an example. The WRAN radio station judges whether or not it is receiving a WRAN radio signal (step S201). If it is not receiving a radio signal, the WRAN radio station returns to step S201 and repeatedly judges whether or not it is receiving a radio signal. If it is receiving a WRAN signal, the WRAN radio station performs synchronization processing of the timing, gain, and frequency of the radio signal in order to perform stable wireless communication (step S202). This synchronization processing may be performed over multiple frames for radio signals transmitted from the same radio station.

[0013] After synchronizing to a state where data communication is possible, the WRAN radio station transmits and receives control messages to and from the opposing radio station and performs a process for connecting to the WRAN system (step S203). This connection process is called a "network entry sequence." When the network entry sequence is completed, the WRAN radio station starts data communication (step S204). Thereafter, while performing data communication, the WRAN radio station constantly judges whether to continue the data communication (step S205), and when data communication is to be terminated, the WRAN radio station transitions to the initial state of step S201.

[0014] As shown in the above-mentioned operation flowchart, conventional WRAN radio stations operate to maintain synchronization with radio signals from specific radio stations. Therefore, after a radio station connects to a WRAN system network, it is normal for it to receive radio signals from a higher-level station in communication, or radio signals exchanged between a higher-level station and a lower-level station, and it is easy to check the presence or absence of a radio station.

[0015] However, when checking the presence or absence of a wireless station, the wireless station to be measured is not always one, so it is necessary to receive wireless signals from multiple wireless stations. In a WRAN system, each wireless station performs wireless communication while switching the wireless transmission timing on a wireless frame basis according to the wireless band allocation described above (for example, FIG. 8). However, since conventional WRAN wireless stations operate to maintain synchronization with the wireless signal from the wireless station they are communicating with, in a wireless environment where the transmitting wireless station switches on a wireless frame basis, it is very difficult to receive the wireless signals transmitted from each wireless station.

[0016] Next, a problem with a wireless receiving device having a function of repeatedly measuring wireless signals transmitted from unspecified wireless stations will be described. Fig. 10 shows an example of an operation flowchart of a conventional wireless receiving device that measures a wireless signal of a WRAN wireless station. The conventional wireless receiving device, like a WRAN wireless station, determines whether or not it is receiving a WRAN wireless signal (step S301), and if it is receiving a WRAN signal, performs a synchronization acquisition process so that data communication becomes possible (step S302).

[0017] When the synchronization acquisition process is completed, the wireless receiving device analyzes the control message of the wireless signal to obtain wireless station identification information (step S303), and further measures wireless propagation characteristic data from the wireless signal (step S304). After that, the wireless receiving device outputs the wireless station identification information obtained in step S303 and the wireless propagation characteristic data measured in step S304 via the network interface (step 305).

[0018] The wireless receiving device receives a wireless signal, performs synchronization acquisition processing, and transitions to a state in which data communication is possible. After that, the wireless receiving device initializes the operating state of the wireless receiving device to the state before synchronization acquisition without performing a network entry sequence with the opposing wireless station. The wireless receiving device then receives a wireless signal from another wireless station again, and repeats the operation from performing synchronization acquisition processing. This operation makes it possible to repeatedly receive wireless signals from unspecified wireless stations, as well as wireless signals from one or two wireless stations currently in communication.

[0019] Problems with such a wireless receiving device will be described below with reference to specific examples. The first problem is that the frequency of measurement by the wireless stations is biased due to the synchronization between the repeat measurement period of the wireless receiving device and the transmission period of each wireless station in the WRAN system. FIG. 11 shows an example of a source wireless station of a wireless signal arriving at a conventional wireless receiving device. In the figure, the number of continuous transmission frames per one time of each wireless station is set to 4 frames, and the repeat measurement period of the wireless receiving device is set to 8 frames. In the scheduling of the WRAN system shown in FIG. 11, the WRAN mobile station A (2-1) repeats starting and stopping transmission in a 4-frame period, and during the period when the WRAN mobile station A (2-1) stops transmitting, the WRAN mobile station B (2-2) and the WRAN mobile station C (2-3) transmit alternately. The wireless receiving device starts synchronization acquisition processing of the next wireless signal in an 8-frame period, but because it is synchronized with the WRAN schedule, it ends up repeating synchronization acquisition of the wireless signal of the WRAN mobile station A (2-1) every time.

[0020] In addition, in an outdoor wireless environment, it is not always possible to ensure stable communication quality, and there are cases where the wireless signal of the WRAN mobile station A (2-1) cannot be received in a certain wireless section. If the repeat measurement period of the wireless receiving device described above shifts and the WRAN mobile station B (2-2) and the WRAN mobile station C (2-3) are alternately captured, it may become impossible to measure the WRAN mobile station A (2-1).

[0021] The repetitive measurement period of a wireless receiving device varies depending on the performance of the wireless receiving device. In addition, the scheduling pattern of a WRAN system is constantly updated during operation depending on the number of WRAN wireless stations, the network topology, and even the amount of transmission data held by each WRAN wireless station. For this reason, it is impossible to define the repetitive measurement period of a wireless receiving device as an optimal single parameter due to the constraints of the WRAN system.

[0022] The second problem is that it is difficult to measure the signals of all wireless stations in the search area. Here, we explain using a characteristic network topology and scheduling pattern of a WRAN system. Figure 12A shows a network topology in which five WRAN wireless stations are connected in series, and Figure 12B shows an example of the scheduling pattern for that case.

[0023] In wireless multi-stage relaying, in addition to the data of the own station, data notified from a lower-level station than the own station must also be transmitted to a higher-level station of the own station. Therefore, in order to transmit data of each mobile station to a base station by multi-stage relaying, as illustrated in FIG. 12B, the closer the mobile station is to the base station, the more wireless resource band is allocated to it. As can be seen more clearly in the serial network topology, the allocation ratio of the wireless resource band to the lowest-level mobile station is very small compared to the entire scheduling pattern. In FIG. 12B, the entire scheduling pattern is 44 frames, while only 4 frames shown by the diagonal hatch pattern are allocated for transmission to the lowest-level WRAN mobile station D (2-4). In this case, depending on the repeated measurement period of the wireless receiving device, the number of measurements is concentrated on the higher-level station with a high allocation ratio of the wireless resource band, and the lower-level station is measured occasionally, or in some cases, not even once.

[0024] As a technology related to interference caused by wireless signals, there is CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance), which is an access control method for collision avoidance that is also adopted in wireless LANs. In CSMA / CA, the waiting time until the next transmission after a collision occurs is changed randomly to avoid repeated collisions between the same wireless stations. By utilizing this, it is possible to reduce bias in the measurement frequency of wireless stations by inserting a random waiting time, similar to CSMA / CA, before starting synchronization acquisition processing in the above-mentioned wireless receiving device. However, even if a random waiting time is inserted, it cannot be guaranteed that the signal of WRAN mobile station D, which transmits only 4 frames out of 44 frames, as shown in FIG. 12B, can be measured.

[0025] The present invention has been made in consideration of the above-described conventional circumstances, and aims to provide a radio signal measurement system that can efficiently perform measurements on radio stations present in a search area. [Means for solving the problem]

[0026] In order to achieve the above object, a wireless signal measurement system according to one aspect of the present invention is configured as follows: That is, the wireless signal measurement system according to the present invention is a wireless signal measurement system that performs measurements on multiple wireless stations of a wireless system to be observed by a wireless signal measurement device, and is characterized in that the wireless signal measurement device receives wireless signals from wireless stations within a search area without connecting to the wireless system, and obtains wireless station identification information that identifies the wireless station that is the sender of the wireless signal based on the wireless signal, and calculates the number of wireless stations present within the search area.

[0027] Here, the radio signal measuring device can be configured to perform synchronization processing for the transmitting radio station based on the received radio signal, acquire radio station identification information of the transmitting radio station based on MAP information in the received radio signal, calculate the number of radio stations present within the search area, measure radio propagation characteristic data for the transmitting radio station based on the preamble in the received radio signal, and output the radio station identification information and the radio propagation characteristic data via a network interface.

[0028] The radio signal measurement system may further comprise a data collection server that collects radio station identification information and radio propagation characteristic data from the radio signal measurement devices.

[0029] In addition, the above-mentioned radio signal measurement system may have a plurality of radio signal measurement devices installed at the same site or different sites, and the data collection server may be configured to collect radio station identification information and radio propagation characteristic data from the plurality of radio signal measurement devices. Effect of the Invention

[0030] According to the present invention, it is possible to provide a radio signal measurement system capable of efficiently performing measurements on radio stations present in a search area. [Brief description of the drawings]

[0031] [Figure 1] 1 is a schematic diagram illustrating an operation image of a wireless signal measurement system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating an example of functional blocks of a wireless signal measuring device. [Diagram 3] A diagram showing the radio frame structure of a WRAN system. [Figure 4] 4A and 4B are diagrams illustrating an example of a timing chart relating to operation modes of the wireless signal measuring device. [Figure 5A] FIG. 4 is a diagram illustrating an example of a flowchart of a main process of the wireless signal measuring device. [Figure 5B]FIG. 5B is a diagram showing an example of a flowchart of a search section process branching from the main process of FIG. 5A. [Figure 5C] FIG. 5B is a diagram showing an example of a flowchart of a measurement section process branched from the main process of FIG. 5A. [Figure 6] 1 is a diagram showing an example of a wireless station management table included in a wireless signal measuring device; [Figure 7] FIG. 1 is a schematic diagram showing an operation image of a conventional WRAN system. [Figure 8] FIG. 1 is a diagram illustrating an example of transmission and reception timing of a conventional WRAN radio station. [Figure 9] FIG. 1 is a diagram showing an example of an operation flowchart of a conventional WRAN radio station. [Figure 10] FIG. 1 is a diagram showing an example of an operation flowchart of a conventional wireless receiving device. [Figure 11] FIG. 1 is a diagram illustrating an example of a source wireless station of a wireless signal arriving at a conventional wireless receiving device. [Figure 12A] FIG. 1 shows a network topology in which five WRAN radio stations are connected in series. [Figure 12B] FIG. 12B is a diagram showing an example of a scheduling pattern in the network topology of FIG. 12A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an operation image of a wireless signal measurement system according to an embodiment of the present invention. The wireless signal measurement system shown in Fig. 1 includes a WRAN system having a plurality of WRAN radio stations, a wireless signal measurement device (3), and a data collection server (4). The WRAN system includes a WRAN base station (1), a WRAN mobile station A (2-1), a WRAN mobile station B (2-2), and a WRAN mobile station C (2-3) as the WRAN radio stations.

[0033] WRAN mobile station A (2-1) and WRAN mobile station B (2-2) are wirelessly connected to the WRAN base station (1). WRAN mobile station C (2-3) is wirelessly connected to WRAN mobile station B (2-2), forming a multi-stage relay configuration. WRAN mobile station A (2-1) to WRAN mobile station C (2-3) are mounted on, for example, a moving vehicle, and can perform wireless communication while moving. This configuration is similar to that of the conventional WRAN system shown in FIG. 7.

[0034] The wireless signal measuring device (3) is arranged, for example, in the vicinity of a search area in which wireless signals from WRAN wireless stations are to be measured. In the example of FIG. 1, a WRAN mobile station 1 (2-1) and a WRAN mobile station 3 (2-3) exist within the search area. The wireless signal measuring device (3) can receive wireless signals from wireless stations (i.e., WRAN mobile station 1 (2-1) and WRAN mobile station 3 (2-3)) existing within the search area, but cannot receive wireless signals from wireless stations (i.e., WRAN base station (1) and WRAN mobile station 2 (2-2)) outside the search area. The wireless signal measuring device (3) receives wireless signals exchanged within the WRAN system, and acquires wireless station identification information and wireless propagation characteristic data of wireless stations within the search area as a result of analyzing and measuring the signals. In addition, the number of wireless stations within the search area can be calculated by counting the number of acquired wireless station identification information. The radio station identification information and radio propagation characteristic data acquired by the radio signal measuring device (3) can be stored within the device or output to the outside of the device via the network interface unit.

[0035] The data collection server (4) collects the measurement data (wireless station identification information and wireless propagation characteristic data) output from the wireless signal measuring device (3) and stores and manages it in a storage device such as a database. The data collection server (4) in Fig. 1 collects measurement data from one wireless signal measuring device (3), but it is also possible to collect measurement data from multiple wireless signal measuring devices (3) installed at the same or different locations and store and manage it in a centralized manner.

[0036] Fig. 2 shows an example of a functional block of the wireless signal measuring device (3) of Fig. 1. In the example of Fig. 2, the wireless signal measuring device (3) includes an antenna 11, an RF (Radio Frequency) unit 12, a control unit 13, a wireless station identification information analysis unit 14, a wireless propagation characteristic data measurement unit 15, and a network interface unit 17.

[0037] In the wireless signal measuring device (3), an antenna 11 receives a wireless signal of the WRAN system and outputs it to an RF unit 12. The RF unit 12 frequency-converts the input wireless signal to a baseband signal and outputs it to a control unit 13, a wireless station identification information analysis unit 14, and a wireless propagation characteristic data measurement unit 15.

[0038] The control unit 13 calculates control information for synchronization processing based on the input baseband signal, and outputs it to the RF unit 12. The RF unit 12 performs synchronization processing using the input control information. The radio station identification information analysis unit 14 analyzes MAP information in the downlink signal of the input baseband signal to obtain radio station identification information, and outputs the radio station identification information to the network interface unit 16. The radio propagation characteristic data measurement unit 15 measures radio propagation characteristic data based on a preamble in the downlink signal of the input baseband signal, and outputs the radio propagation characteristic data to the network interface unit 17. The network interface unit 17 outputs the radio station identification information obtained by the radio station identification information analysis unit 14 and the radio propagation characteristic data obtained by the radio propagation characteristic data measurement unit 15 from the radio signal measurement device 3. At this time, the network interface unit 17 outputs the radio station identification information and the radio propagation characteristic data in a structure that combines them into one data so that they can be managed on a radio station-by-radio station basis.

[0039] Figure 3 shows the radio frame configuration of a WRAN system. In Figure 3, the vertical axis represents frequency, and the horizontal axis represents time. As shown in Figure 3, the radio frame of a WRAN system is a duplex radio frame using TDD (Time Division Duplex). The radio frame period (10 milliseconds) is divided into a DL subframe section for transmitting and receiving downlink signals, a UL subframe section for transmitting and receiving uplink signals, and a TTG (Transmit / receive Transition Gap) and RTG (Receive / transmit Transition Gap) that are gap times to avoid overlapping of the downlink and uplink signals.

[0040] The signals in the DL subframe section and the UL subframe section will be described. In the DL subframe section, the preamble is a signal for performing synchronization processing in the reception processing of the downlink signal. The FCH (Frame Check Header) is a signal including configuration information of the MAP information (such as modulation method, error correction method, and MAP data size). The MAP information is a control message of the WRAN, and is composed of the DL-MAP and the UL-MAP. The DL-MAP is an area including the MAP data length, the radio frame number, the radio station identification information, the DL subframe section length, and the DL data burst configuration information. The UL-MAP is an area including the UL subframe section length and the UL data burst configuration information. The DL data burst area is an area including the downlink user data. In the UR subframe section, the ranging area is an area including the signal required for the synchronization processing of the uplink signal from the lower station. The UL data burst area is an area including the uplink user data.

[0041] The wireless signal measuring device (3) of this example measures downlink signals, acquires wireless station identification information from the DL-MAP described above, and measures wireless propagation characteristic data based on the preamble described above. The wireless signal measuring device (3) is capable of receiving wireless signals from WRAN wireless stations present in the search area shown in Fig. 1, and measures downlink signals. Therefore, the downlink signals transmitted from the WRAN mobile station A (2-1) and the WRAN mobile station C (2-3) of frame numbers [4] to [9] in the transmission and reception timing of each wireless station shown in Fig. 8 are measured by the wireless signal measuring device (3).

[0042] The radio signal measurement method in the radio signal measurement system of this example will be described below. An example of a timing chart relating to the operation modes of the radio signal measurement device (3) is shown in Fig. 4. Fig. 4 shows that the radio signal measurement device (3) alternates between two operation modes, a search period and a measurement period. As shown in the upper part of Fig. 4, both the search period and the measurement period are configured to be sufficiently longer than the radio frame period (10 milliseconds) and the WRAN scheduling pattern.

[0043] The roles of the search section and the measurement section will be described. In the search section, wireless stations present in the search area are detected, and in the measurement section, the wireless propagation characteristic data is measured while selecting wireless stations so that the measurement frequency of the wireless stations is not biased according to the information of the wireless stations detected in the search section, and the operation of outputting the data via the network interface is repeated. Here, the selection method that does not cause bias will be described. For example, for all wireless stations detected in the search section, the measurement is repeated until each of them can be detected once in the measurement section. At that time, if a wireless station that has already been measured is detected before the measurement of all wireless stations is completed, the measurement of the wireless propagation characteristic data of that wireless station is skipped, and the operation is continued to detect undetected wireless stations. Thereafter, the skip is repeated under the same conditions until the measurement of all wireless stations is completed. This operation makes it possible to avoid a sudden increase in the number of measurements of a specific wireless station and the existence of a wireless station that cannot be measured even once. In addition, although the above describes an operation that skips after one measurement, it is possible to make adjustments such as increasing the number of measurements to two or more to reduce the number of skips, or to tolerate momentary bias in the number of measurements as long as there is no bias in the long term.

[0044] Next, the operation of the wireless signal measuring device (3) will be described with reference to the flowcharts shown in Figures 5A to 5C. Figure 5A shows an example of a flowchart of main processing in the wireless signal measuring device (3). The wireless signal measuring device (3), like a WRAN radio station, determines whether or not it is receiving a WRAN wireless signal (step S101), and if it is receiving a WRAN signal, performs synchronization acquisition processing so that data communication becomes possible (step S102).

[0045] Thereafter, the radio signal measuring device (3) branches to search section processing or measurement processing according to the state of timer control of the radio signal measuring device (step S103). That is, during the search section, it branches to search section processing (step S104), and during the measurement section, it branches to measurement section processing (step S105). Details of the timer control will be described later.

[0046] 5B shows an example of a flow chart of the search section process (step S104) branched from the main process. In the search section process, the wireless signal measuring device (3) analyzes MAP information in the received downlink signal and acquires wireless station identification information (step S121). After that, the wireless signal measuring device (3) updates a wireless station management table (FIG. 6) (to be described later) based on the acquired wireless station identification information (step S122).

[0047] 5C shows an example of a flowchart of the measurement section process (step S105) branched from the main process. In the measurement section process, the wireless signal measuring device (3) analyzes the MAP information in the received downlink signal, as in the search section process, and acquires wireless station identification information (step S141). After that, the wireless signal measuring device (3) refers to the wireless station management table using the acquired wireless station identification information as a key, and determines whether the wireless propagation characteristic data for the currently detected wireless station is unmeasured or has been measured (step S142).

[0048] If it is determined that the radio propagation characteristic data has not been measured, the radio signal measuring device (3) measures the radio propagation characteristic data based on the preamble in the received downlink signal (step S143), and outputs the radio station identification information and the radio propagation characteristic data obtained in the current measurement from the network interface (step S144). In addition, the radio signal measuring device (3) updates the radio station management table based on the radio station identification information and the radio propagation characteristic data obtained in the current measurement (step S145). Note that, if it is determined in the above-mentioned determination (step S142) that the radio propagation characteristic data has been measured, the processes of steps S143 to S145 are omitted.

[0049] Next, the three timer controls implemented by the radio signal measuring device (3) of this example will be described. The first timer is a "search section end waiting timer" that is initialized at the start of the search section and starts timing for the search section. When the first timer expires, the measurement section is started and the control of the second timer is transferred. The second timer is a "search section and measurement section switching timer" that is initialized at the start of the measurement section and starts timing for the measurement section. When the second timer expires, the search section is started and the control of the first timer (search section end waiting timer) is transferred. By controlling these two timers, an operation of alternately repeating the search section and the measurement section is realized.

[0050] The third timer is a "timer for waiting for completion of measurement of all wireless stations in the measurement section", which is initialized at the start of the measurement section and starts counting the time set for measuring the wireless propagation characteristic data of all wireless stations detected in the search section. In the measurement section, the wireless propagation characteristic data is measured for all wireless stations detected in the search section one by one. Then, when the third timer expires, the third timer is reinitialized and counting is restarted, and the measurement process of the wireless propagation characteristic data of each wireless station is repeated. Note that if there is a wireless station for which the wireless propagation characteristic data could not be measured when the third timer expires, the wireless station may be excluded from the subsequent measurement targets and the third timer may be restarted, and the measurement process of the wireless propagation characteristic data may be repeated for the remaining wireless stations.

[0051] Next, the wireless station management table of the wireless signal measuring device (3) will be described. An example of the wireless station management table is shown in Fig. 6. In the wireless station management table of Fig. 6, each record (row) in the horizontal direction corresponds to each wireless station, and each item (column) in the vertical direction represents each parameter (information or status) related to the wireless station.

[0052] The leftmost item in the radio station management table, "No.", stores a number assigned to each radio station in ascending order. The radio station management table needs to be large enough to accommodate the number of radio stations that are to be simultaneously measured. The second item from the left in the radio station management table, "radio station identification information," stores the radio station identification information of radio stations detected in the search area. If the same radio station is detected within the search area, there is no need to add or update the radio station identification information. The radio signal measuring device (3) can calculate the number of radio stations within the search area by counting the number of records in which "radio station identification information" is stored in the radio station management table.

[0053] The "measurement status during search interval," the third item from the left in the wireless station management table, is initialized to "not measured" for all wireless stations at the start of the search interval. After that, each time a wireless station is detected during the search interval, the "measurement status during search interval" of that wireless station is updated to "measured." If the same wireless station is detected within the search interval, the "measurement status during search interval" of that wireless station does not need to be updated because it is already "measured." In the search interval, wireless station identification information can be obtained at wireless frame intervals without measuring wireless propagation characteristic data, so wireless identification information can be obtained without missing anything, even for wireless stations with a small wireless resource bandwidth.

[0054] The rightmost item of the wireless station management table, "measurement status during measurement interval", is initialized to "not measured" for all wireless stations whose "measurement status during search interval" is "measured" at the start of the measurement interval. Thereafter, each time wireless propagation characteristic data is measured during the measurement interval, the "measurement status during measurement interval" of the wireless station is updated to "measured". When the time (third timer) set for measuring the wireless propagation characteristic data of all wireless stations detected in the search interval has elapsed in the measurement interval, the "measurement status during measurement interval" of all wireless stations whose "measurement status during search interval" is "measured" is initialized to "not measured", and the measurement of the wireless propagation characteristic data is repeated. By managing the table in this way, the wireless signal measuring device (3) can repeatedly measure the wireless propagation characteristic data in the measurement interval for all wireless stations detected in the search interval without bias. For example, even if there is a wireless station that is probabilistically detected infrequently, such as WRAN mobile station D shown in FIG. 12B, if it is detected in the search section and added to the list, it is possible to wait until WRAN mobile station D can be detected in the repeated measurement operation in the measurement section until the third timer expires.As a result, it is possible to measure all wireless stations detected in the search section without bias in the measurement section.

[0055] Next, the updating of the wireless station management table in two special situations that are assumed to occur in the measurement section will be described. The first situation is when a wireless station that has not been measured in the search section is measured in the measurement section. In the first situation, the wireless signal measuring device (3) adds the wireless station identification number acquired in the measurement section to the "wireless station identification number" in the wireless station management table, and updates the "measurement status during the search section" of the wireless station to "measured". Then, after measuring the wireless propagation characteristic data and outputting the data via the network interface, the wireless station updates the "measurement status during the measurement section" of the wireless station to "measured".

[0056] The second situation is a situation in which the radio station measured in the search section cannot be measured for a long time. In the second situation, the radio signal measuring device (3) deletes all the radio stations that could not be measured from the radio station management table when the third timer expires. Specifically, the "measurement state during the search section" corresponding to the deleted radio station is updated to "not measured", and the "measurement state during the measurement section" is updated to "not measured". By deleting the radio station from the radio station management table, the radio station that could not be measured has the same status as the state in which it could not be measured in the search section, and when the measurement section is repeated, it is not necessary to wait even if it cannot be measured, and it is possible to avoid deadlock. When the deleted radio station is measured again, the radio station management table is updated in the same manner as the first situation described above. In this way, by flexibly updating the radio station management table according to not only the result of the search section but also the measurement state during the measurement section, it is possible to avoid bias in the number of measurements of each radio station and to increase the number of measurements of all radio stations.

[0057] As described above, the wireless signal measurement system of this example includes a wireless signal measurement device (3) for performing measurements on multiple WRAN wireless stations of a WRAN system to be observed. The wireless signal measurement device (3) receives wireless signals from WRAN wireless stations (e.g., WRAN mobile station 1 (2-1), WRAN mobile station 3 (2-3)) in a search area without connecting to the WRAN system, and obtains wireless station identification information for identifying the WRAN wireless station that sent the wireless signal based on the wireless signal, and calculates the number of WRAN wireless stations present in the search area. With this configuration, it is possible to properly grasp the wireless station identification information and the number of WRAN wireless stations present in the search area. Therefore, it is possible to efficiently perform measurements on wireless signals from WRAN wireless stations present in the search area.

[0058] Although the embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take various other embodiments, and various modifications such as omissions and substitutions can be made without departing from the gist of the present invention. These embodiments and modifications are included in the scope and gist of the invention described in this specification, etc., and are included in the scope of the invention described in the claims and their equivalents.

[0059] Furthermore, the present invention can be provided not only as devices such as those described above or as a system composed of these devices, but also as methods executed by these devices, programs for causing a processor to realize the functions of these devices, and storage media for storing such programs in a computer-readable format. [Industrial Applicability]

[0060] The present invention can be used in a wireless signal measurement system that performs measurements on a plurality of wireless stations in a wireless system that is an object of observation. [Explanation of symbols]

[0061] 1: WRAN base station, 2: WRAN mobile station, 3: wireless signal measuring device, 4: data collection server, 11: antenna, 12: RF unit, 13: control unit, 14: wireless station identification information analysis unit, 15: wireless propagation characteristic data measuring unit, 16: network interface unit

Claims

1. A wireless signal measurement system that performs measurements on a plurality of wireless stations of a wireless system to be observed by a wireless signal measurement device, comprising: A radio signal measuring system characterized in that the radio signal measuring device receives radio signals from radio stations within a search area without connecting to the radio system, obtains radio station identification information that identifies the radio station that sent the radio signal based on the radio signal, and calculates the number of radio stations present within the search area.

2. 2. The wireless signal measurement system according to claim 1, The wireless signal measuring device includes: performing a synchronization process for the source wireless station based on the received wireless signal; Calculating the number of wireless stations present within the search area while acquiring wireless station identification information of the wireless station that is the transmission source based on MAP information in the received wireless signal; measuring radio propagation characteristic data relating to the source radio station based on a preamble in the received radio signal; A radio signal measuring system, comprising: a network interface for outputting said radio station identification information and said radio propagation characteristic data.

3. 3. The wireless signal measurement system according to claim 2, The radio signal measuring system further comprises a data collection server that collects the radio station identification information and the radio propagation characteristic data from the radio signal measuring device.

4. 4. The wireless signal measurement system according to claim 3, A plurality of wireless signal measuring devices installed at the same site or at different sites are provided, The wireless signal measuring system according to the present invention, wherein the data collection server collects the wireless station identification information and the wireless propagation characteristic data from the plurality of wireless signal measuring devices.

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