Wireless communication systems and radios

Abstract

The system allows for real-time monitoring of precipitation conditions in the propagation path between opposing radios while transmitting and receiving signals, enabling adjustment of the frequency bandwidth. [Solution] In a wireless communication system according to one embodiment of the present invention, the master station a stores a portion of the transmission signal to the slave station b as a known signal in memory 17a, the correlation calculation unit 19a performs a correlation calculation between the reflected signal reflected in the propagation path 30 between the transmission signal and the slave station b and the known signal in memory 17a, the precipitation estimation unit 20a estimates the precipitation conditions in the propagation path 30 based on the results of the correlation calculation, and the communication parameter control unit 21a changes the frequency bandwidth according to the estimated result of the precipitation conditions in the propagation path 30.

Description

[Technical Field]

[0001] The present invention relates to a wireless communication system equipped with radio stations that transmit and receive signals between opposing radio devices. [Background technology]

[0002] In recent years, wireless communication has faced challenges in securing wide bandwidths at lower carrier frequencies due to frequency constraints. Therefore, broadband communication is implemented using higher carrier frequencies such as the sub-millimeter wave band (3GHz to 30GHz) and millimeter wave band (30GHz to 300GHz). However, in outdoor wireless communication, precipitation such as rain and snow causes radio wave attenuation, degrading communication quality. This attenuation is particularly significant at carrier frequencies above the sub-millimeter wave and millimeter wave ranges, where the raindrop diameter is equal to or less than the wavelength.

[0003] In environments where radio wave attenuation occurs due to precipitation, it is common to use adaptive modulation schemes that optimize the modulation level and error correction coding rate to match the propagation path characteristics to prevent transmission errors. However, while this adaptive modulation scheme prevents transmission errors, it can lead to problems such as reduced communication speed.

[0004] To address these problems, in addition to performing adaptive modulation during radio wave attenuation caused by precipitation, adaptive bandwidth control is being considered to adaptively vary the bandwidth. The basic idea of ​​adaptive bandwidth control is to utilize the fact that the amount of radio wave attenuation increases with the intensity of precipitation. In other words, if the channel arrangement and the location of radio stations are set appropriately, even if the bandwidth is expanded during precipitation, interference to other radio stations will be greatly reduced due to radio wave attenuation, making it less likely to cause problems for wireless communication.

[0005] Prior art in the field of the present invention includes the following. For example, Patent Document 1 discloses a base station device that measures the reception level from any subscriber base station and transmits it to the subscriber base station, and a subscriber base station that stores the optimal reception level in advance and adjusts the transmission power according to the difference between the reception level transmitted from the base station device and the optimal reception level. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-167500 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In order to perform the variable bandwidth control described above, it is necessary to accurately understand the amount and location of precipitation so as not to affect other radio stations. While it is possible to use weather data published by the Japan Meteorological Agency to understand precipitation, there are problems such as the coarse mesh of the precipitation location data and the low update frequency of about 5 minutes. In addition, recent torrential downpours have drastic temporal variations in precipitation and can occur locally, so in order to avoid interfering with other radio stations, it is necessary to quickly determine whether or not there is precipitation in the target radio communication section.

[0008] This invention has been made in view of the above-mentioned conventional circumstances, and aims to enable the frequency bandwidth to be changed in real time by grasping the precipitation conditions in the propagation path between opposing radios while transmitting and receiving between them. [Means for solving the problem]

[0009] A wireless communication system according to one aspect of the present invention is a wireless communication system comprising radio stations that transmit and receive between opposing radios, characterized in that each radio stores a portion of the transmission signal to the opposing radio as a known signal in memory, estimates the precipitation conditions in the propagation path based on the result of a correlation calculation between the reflected signal reflected by the transmission signal in the propagation path between the opposing radios and the known signal, and changes the frequency bandwidth according to the estimated result of the precipitation conditions in the propagation path.

[0010] In the above wireless communication system, each radio may have a filter configured to extract frequency components that vary significantly over time due to precipitation, and the high-pass filter may be applied to the result of the correlation calculation for each frame, and the result may be used as a precipitation profile to estimate the precipitation conditions along the propagation path.

[0011] Furthermore, in the above-described wireless communication system, each radio may calculate the power intensity of the reflected signal and compare the amount of radio wave attenuation estimated from the estimated precipitation conditions of the propagation path with the amount of radio wave attenuation calculated from the power intensity of the reflected signal to determine the need to change the frequency bandwidth.

[0012] Furthermore, the above-described wireless communication system may include a centralized management station that centrally manages multiple radio stations, and the centralized management station may aggregate the estimated precipitation conditions along the propagation path from each radio station and control the change in the frequency bandwidth of each radio station based on the estimated precipitation conditions along the propagation path from each radio station.

[0013] Furthermore, in the above-described wireless communication system, each radio may observe the spectrum of the surrounding frequencies of the operating frequency and determine whether or not the frequency bandwidth can be expanded based on the observation results of the spectrum of the surrounding frequencies.

[0014] A wireless device according to another aspect of the present invention is a wireless device that transmits and receives with an opposing wireless device, stores a part of a transmission signal to an opposing wireless device in a memory as a known signal, and estimates a precipitation situation of a propagation path based on a result of a correlation operation between a reflected signal reflected by the propagation path between the wireless device and the opposing wireless device and the known signal, and changes a frequency bandwidth according to an estimation result of the precipitation situation of the propagation path.

Advantages of the Invention

[0015] According to the present invention, while transmitting and receiving between opposing wireless devices, it becomes possible to grasp the precipitation situation of the propagation path between the wireless devices in real time and change the frequency bandwidth.

Brief Description of the Drawings

[0016] [Figure 1] It is a diagram showing a configuration example of a wireless communication system according to a first embodiment of the present invention. [[ID=十六]] [[ID=十七]] [Figure 2] It is a diagram showing an example of a correlation operation result based on a transmission signal and a received signal (reflected wave). [Figure 3] It is a diagram showing a configuration example of a wireless communication system according to a second embodiment of the present invention. [Figure 4] It is a diagram showing an example of a power map in which power information is visualized on a map. [Figure 5] It is a diagram showing an example of synthesizing power maps of a plurality of wireless stations. [Figure 6] It is a diagram showing a configuration example of a wireless communication system according to a third embodiment of the present invention. [Figure 7] It is a diagram showing an example of a frequency spectrum when the frequency bandwidth is not expanded. [Figure 8] It is a diagram showing an example of a frequency spectrum when the frequency bandwidth is expanded.

Modes for Carrying Out the Invention

[0017] A wireless communication system according to one embodiment of the present invention will be described with reference to the drawings. Here, a wireless communication system equipped with radio stations that transmit and receive between radios installed facing each other in a line-of-sight environment will be described as an example. The distance between the opposing radios is generally 10 km or less, and in many cases is about 1 to 2 km.

[0018] [First Embodiment] Figure 1 shows an example configuration of a wireless communication system according to the first embodiment of the present invention. In the wireless communication system according to the first embodiment, a main station radio a (hereinafter simply referred to as "main station a") and a slave station radio b (hereinafter simply referred to as "main station b") communicate wirelessly in a duplex manner via a propagation path 30, which is a wireless communication section. As a duplex method, for example, TDD (Time Division Duplex), which switches the transmission and reception timing over time, is used.

[0019] Main station a includes a modulation unit 11a, a transmitting RF unit 12a, a TDD switch 13a, an antenna 14a, a receiving RF unit 15a, a demodulation unit 16a, a memory 17a, an RSSI unit 18a, a correlation calculation unit 19a, a precipitation estimation unit 20a, and a communication parameter control unit 21a. Similarly, slave station b includes a modulation unit 11b, a transmitting RF unit 12b, a TDD switch 13b, an antenna 14b, a receiving RF unit 15b, a demodulation unit 16b, a memory 17b, an RSSI unit 18b, a correlation calculation unit 19b, a precipitation estimation unit 20b, and a communication parameter control unit 21b.

[0020] At the main station a, the modulation unit 11a performs error correction coding and modulation processing on the information to be transmitted to the slave station b. For example, LDPC (Low Density Parity Check) can be used as the error correction method. For example, OFDM (Orthogonal Frequency Division Multiplexing) can be used as the modulation method. Note that error correction and modulation methods other than those mentioned above may also be used.

[0021] The signal processed by the modulation unit 11a is transferred to the memory 17a and the transmission RF unit 12a. The memory 17a stores the signal of the latter half of the transmission frame (shaded portion) as a known transmission signal in the transmission signal exemplified in Figure 2. The transmission RF unit 12a frequency-converts the signal from the modulation unit 11a to the carrier frequency of wireless communication and amplifies the transmission power using a power amplifier before outputting it.

[0022] The transmission signal output from the transmitting RF unit 12a is transmitted into space as radio waves by the antenna 14a via the TDD switch 13a. The operation of the TDD switch 13a will now be explained with reference to Figure 2. The TDD switch 13a is controlled to conduct between the transmitting RF unit 12a and the antenna 14a during the TDD transmission period, and to conduct between the receiving RF unit 15a and the TDD switch 13a during other periods.

[0023] The transmission signal sent from antenna 14a reaches antenna 14b of slave station b via propagation path 30. At slave station b, the signal received by antenna 14b is input to demodulation unit 16b via TDD switch 13b and receiving RF unit 15b. Demodulation unit 16b performs demodulation processing on the signal input from receiving RF unit 15b, corresponding to the modulation scheme of modulation unit 11a. Various algorithms exist for demodulation processing, but since the demodulation algorithm is not essential to this invention, its explanation is omitted.

[0024] Here, if there is a reflective object in the propagation path 30, the transmission signal sent from antenna 14a is reflected by the reflective object and reaches antenna 14a of main station a as a reflected signal. Examples of reflective objects include buildings, trees, and precipitation (rainfall or snowfall). The reflected signal reaches antenna 14a with a delay time due to radio wave propagation, but at that point the TDD reception period has begun, and the TDD switch 13a has been switched to conduct between antenna 14a and the receiving RF unit 15a. As a result, the reflected signal is input to the receiving RF unit 15a.

[0025] The receiving RF unit 15a converts the input carrier frequency signal to a baseband frequency and outputs it. The signal output from the receiving RF unit 15a is input to the demodulation unit 16a, the RSSI unit 18a, and the correlation calculation unit 19a. The RSSI unit 18a calculates the RSSI (Received Signal Strength Indication), which is an indicator of the power strength of the received signal that has arrived from the slave station b side (in this case, the reflected signal that has arrived from the slave station b side after the signal transmitted from the master station a to slave station b has been reflected by reflectors in the propagation path 30). The RSSI will have different values ​​depending on the transmitted signal power and antenna gain.

[0026] The correlation calculation unit 19a receives the reflected signal received during the TDD reception period and the transmitted known signal from the previous transmission period stored in memory 17a. If the transmitted known signal is s(t) and the received reflected signal is r(t), the correlation calculation is performed between the transmitted known signal s(t) and the received reflected signal r(t) according to equation (1) below, and the correlation calculation result c(τ) is obtained.

[0027]

number

[0028] In equation (1) above, T is the length of the transmitted known signal s(t). The correlation calculation result c(τ) is the reflected wave profile, and |c(τ)| 2 τ represents the power level of the reflected wave. τ is the delay time of the reflected wave and can be converted to the distance to the reflector. Figure 2 shows an example of a known transmitted signal s(t), a received reflected signal r(t), and the correlation calculation result c(τ). The correlation calculation unit 19a performs such a correlation calculation for each TDD frame and redefines the cross-correlation calculation result c(n,τ) with frame number n.

[0029] The cross-correlation calculation result c(n,τ) obtained by the correlation calculation unit 19a is input to the precipitation estimation unit 20a. The precipitation estimation unit 20a applies a high-pass filter to the cross-correlation calculation result c(n,τ) in the frame direction (time direction) n, as shown in equation (2) below.

[0030]

number

[0031] In equation (2) above, the HPF function is assumed to be a high-pass filter that extracts highly variable frequency components caused by precipitation in the propagation path 30. HPF (τ) is a component that fluctuates greatly in the frame direction (time direction), and it can be inferred that it represents the reflection component due to precipitation. In other words, P HPF (τ) is a small value in clear weather, but it increases with increasing rainfall. This is because as rainfall increases, the amount of radio waves reflected by raindrops increases.

[0032] Therefore, P HPF (τ) can be used as a precipitation profile and can be used to estimate precipitation conditions. Here, the distance to the reflector corresponds to time τ, and the precipitation is P HPF This corresponds to the magnitude of the (τ) value. The precipitation estimated by the precipitation estimation unit 20a is input to the communication parameter control unit 21a. The above explanation pertains to the main station a, but the same precipitation estimation is performed at the slave station b, and the result is input to the communication parameter control unit 21b.

[0033] The communication parameter control unit 21a of the main station a and the communication parameter control unit 21b of the slave station b share precipitation information by transferring the results of precipitation estimation to each other. Alternatively, the slave station b may transfer the results of precipitation estimation to the main station a, and only the main station a may be aware of the precipitation information from both. Here, communication takes place between the communication parameter control unit 21a and the communication parameter control unit 21b, but the communication line may be wireless communication via the propagation path 30 or other wireless communication lines, or it may be a wired communication line such as a cable, and the type and form of the communication line are not limited.

[0034] Precipitation information shared between master station a and slave station b is used to adaptively control the modulation multi-level, error correction coding rate, and frequency bandwidth according to the amount of precipitation when precipitation is observed in the propagation path 30, which is the radio communication section. For example, precipitation profile P HPF Based on the current precipitation estimated from (τ) and the relationship between precipitation and radio wave attenuation [dB / km] that is known in advance, the amount of radio wave attenuation due to precipitation across the entire propagation path can be estimated. Then, by expanding the bandwidth so that a wider frequency bandwidth is required as the radio wave attenuation due to precipitation increases, stable communication quality can be obtained regardless of precipitation conditions.

[0035] Here, the master station a and the slave station b share precipitation information obtained by their own station (e.g., master station a) and precipitation information obtained by the other station (e.g., slave station b). If the precipitation within the propagation path 30 is uniform overall, the respective precipitation information will be approximately equal. On the other hand, if there is a bias in the precipitation situation, the difference between the respective precipitation information will be large. In this case, it is desirable to prioritize using the precipitation information that more accurately represents the impact of the precipitation, that is, the precipitation information from the station with the heavier precipitation, to estimate the radio wave attenuation and perform bandwidth expansion. Both master station a and slave station b may autonomously determine the need for bandwidth expansion, or only master station a may determine the need for bandwidth expansion and transmit the result to slave station b to perform bandwidth expansion.

[0036] Furthermore, while it is possible to determine the need for bandwidth expansion based solely on the estimated radio wave attenuation, using RSSI in conjunction allows for a more accurate determination of whether or not the attenuation is due to precipitation. In other words, the precipitation profile P calculated by the correlation calculation unit 19a HPFIt is desirable to compare the estimated radio wave attenuation based on (τ) with the measured radio wave attenuation based on RSSI observed by the RSSI unit 18a, and if there is no significant difference between them (i.e., the difference between the estimated value and the measured value is less than or equal to a predetermined value), to determine that the attenuation is due to precipitation and to expand the bandwidth. Although it is also possible to make a judgment based solely on RSSI, in this case it is difficult to distinguish from RSSI decreases caused by factors other than precipitation, such as antenna misalignment, and there is a concern that bandwidth expansion may be mistakenly performed on clear days, causing interference to other radio stations.

[0037] The extended frequency bandwidth may be varied according to the estimated or measured magnitude of radio wave attenuation. For example, if the frequency bandwidth is 50 MHz for clear or cloudy days when radio wave attenuation is below the first threshold, it can be controlled to 100 MHz for normal rain where radio wave attenuation is above the first threshold but below the second threshold, and to 400 MHz for heavy rain where radio wave attenuation is above the second threshold but below the third threshold. This makes it possible to stably maintain the desired communication capacity and communication quality regardless of rainfall conditions.

[0038] As described above, in the wireless communication system according to the first embodiment, the master station a stores a portion of the transmission signal to the slave station b as a known signal in memory 17a, the correlation calculation unit 19a performs a correlation calculation between the reflected signal reflected in the propagation path 30 between the master station a and the slave station b and the known signal in memory 17a, the precipitation estimation unit 20a estimates the precipitation conditions in the propagation path 30 based on the results of the correlation calculation, and the communication parameter control unit 21a changes the frequency bandwidth according to the estimated result of the precipitation conditions in the propagation path 30. With this configuration, the master station a can grasp the precipitation conditions in the propagation path 30 in real time and change the frequency bandwidth while transmitting and receiving with the slave station b.

[0039] Also, in the slave station b, a part of the transmission signal to the master station a is stored in the memory 17b as a known signal. The correlation calculation unit 19b performs a correlation calculation between the reflected signal obtained by reflecting the transmission signal on the propagation path 30 with the master station a and the known signal in the memory 17b. The precipitation estimation unit 20b estimates the precipitation situation on the propagation path 30 based on the result of the correlation calculation, and the communication parameter control unit 21b changes the frequency bandwidth according to the estimation result of the precipitation situation on the propagation path 30. With such a configuration, the slave station b can grasp the precipitation situation on the propagation path 30 in real time and change the frequency bandwidth while performing transmission and reception with the master station a.

[0040] [Second Embodiment] FIG. 3 shows a configuration example of a wireless communication system according to the second embodiment of the present invention. The wireless communication system according to the second embodiment includes wireless stations A, B, C and a centralized management station D. The wireless stations A, B, C each have a master station a and a slave station b according to the first embodiment shown in FIG. 1, a power map generation unit 31a associated with the master station a, and a power map generation unit 31b associated with the master station b.

[0041] The master station a of the wireless station A transfers the used wireless parameters and the precipitation profile P HPF (τ) to the power map generation unit 31a. Similarly, the slave station b of the wireless station A transfers the used wireless parameters and the precipitation profile P HPF (τ) to the power map generation unit 31b. Examples of the wireless parameters include wireless communication frequency, output power, antenna directivity gain, position information of the wireless station, etc., which are transferred as known information. The precipitation profile P HPF (τ) is the estimation result of the precipitation amount described in the first configuration example.

[0042] The power map generation units 31a and 31b of radio station A generate a power map that visualizes the power information in the radio area of ​​radio station A on a map, based on this information. Figure 4 shows an example of a power map, showing the locations of the main station and slave stations on the map, and representing the power level of radio waves by the intensity of the colors radiated from the main station and slave stations. Figure 4(a) shows the situation on a clear day, and it can be determined that radio waves are reaching far distances. On the other hand, Figure 4(b) shows the situation on a rainy day, and it can be determined that radio waves are attenuated due to precipitation.

[0043] Using such power maps, the location and power information of the master and slave stations can be easily determined. Furthermore, if other radio stations exist within the range of the radio waves, the amount of interference they experience can be determined. Power maps are generated similarly not only for radio station A, but also for radio stations B and C. These power maps, radio parameters, and precipitation profile P are used. HPF (τ) is transmitted to the central control station D. Based on the information aggregated from each radio station, the central control station D sets the radio parameters for each radio station.

[0044] Figure 5 shows an example of a power map created by combining the power maps of radio station A and radio station B at the central control station D. In Figure 5, "Master station A" is the master station a of radio station A, "Subordinate station A" is the subordinate station b of radio station A, "Master station B" is the master station a of radio station B, and "Subordinate station B" is the subordinate station b of radio station B. Figure 5(a) shows the situation in clear weather, and Figure 5(b) shows the situation in rainy weather. These power maps can also be displayed on a display device (not shown) that is communicatively connected to the central control station D for user verification.

[0045] Figure 5(a) shows that in clear weather, the radio signal from main station A reaches substation B with high power, and if the same frequency is used, interference from main station A to substation B will occur. Therefore, in clear weather, it is desirable for radio stations A and B to use different frequencies. On the other hand, Figure 5(b) shows that in rainy weather, the radio signals from radio stations A and B do not interfere with each other due to radio wave attenuation caused by precipitation. Therefore, in rainy weather, it is not a problem even if both radio stations A and B expand their frequency bandwidth and use the same frequency.

[0046] Here, the frequency band that radio station A uses in clear weather is f. A Let f be the frequency band that radio station B uses when the weather is clear. B These frequency bands f A ,f B Assume they are adjacent. In this case, during rainy weather, the central control station D will use the frequency band f for radio station A. A frequency band f B A control signal is sent to the side that expands the frequency band by a factor of two, and for radio station B, the frequency band f to be used is specified. B frequency band f A It transmits a control signal that expands the frequency band by a factor of two. In other words, central control station D transmits a control signal that expands the frequency band f A and frequency band f B The combined frequency band f AB A control signal instructing the expansion of the frequency bandwidth is transmitted to radio stations A and B so that the same frequency band can be shared by both radio stations A and B. Radio stations A and B expand the frequency bandwidth according to the control signal received from the central control station D. In the above explanation, the center frequency of the frequency band used by radio stations A and B shifts as the frequency bandwidth is expanded, but it is also possible to expand the frequency bandwidth without shifting the center frequency.

[0047] As described above, the wireless communication system according to the second embodiment includes a centralized management station D that centrally manages multiple radio stations A, B, and C. The centralized management station D collects the estimated precipitation conditions of each radio station A, B, and C along its propagation path 30, and controls the frequency bandwidth of radio stations A, B, and C based on these estimated results. In this way, by having the centralized management station D understand the status of radio stations A, B, and C and coordinate their operation, it becomes possible to share frequencies with improved frequency utilization efficiency while avoiding interference between the radio signals of radio stations A, B, and C with high accuracy.

[0048] [Third Embodiment] Figure 6 shows an example configuration of a wireless communication system according to a third embodiment of the present invention. The wireless communication system according to the third embodiment includes radio stations A, B, and C. Radio stations A, B, and C each have a main station a and a slave station b according to the first embodiment shown in Figure 1, an interference wave measurement unit 41a attached to the main station a, and an interference wave measurement unit 41b attached to the main station b. The wireless communication system according to the second embodiment was a frequency sharing system in which the status of each radio station was centrally managed by a central management station, but the wireless communication system according to the third embodiment is a frequency sharing system in which each radio functions autonomously and in a distributed manner.

[0049] At each radio station, the interference wave measurement units 41a and 41b measure the spectrum of the frequency band used by the radio station (its own channel) and the surrounding frequency bands (adjacent channels). In other words, each radio station has a wideband receiving function that allows it to observe frequency bands other than the frequency band used by the radio station in clear weather, and observes the spectrum of its own channel and adjacent channels by performing processing such as FFT (Fast Fourier Transform) on the received signal.

[0050] Figure 7 shows an example of a frequency spectrum observation without expanding the frequency bandwidth. Figure 8 shows an example of a frequency spectrum observation with expanded frequency bandwidth. Figures 7(a) and 8(a) are examples of frequency spectrum observations under clear skies, while Figures 7(b) and 8(b) are examples of frequency spectrum observations under rainy skies.

[0051] As shown in Figure 7(a), suppose another radio station (e.g., radio station B) located close to your own radio station (e.g., radio station A) is operating on an adjacent channel to your own. If we consider the propagation paths of your radio station and the other radio station to be dual, then when the frequency bandwidths of your radio station and the other radio station are expanded during clear weather, they will interfere with each other, making radio communication difficult, as shown in Figure 8(a). On the other hand, during precipitation, as shown in Figure 7(b), the power intensity of the radio signals and interference waves of your radio station and the other radio station are greatly attenuated. Also, precipitation profile P HPF Since the presence or absence of precipitation can be confirmed from (τ), it can be determined that the attenuation of power intensity is caused by precipitation. In this case, as shown in Figure 8(b), both the local radio station and other radio stations determine that the frequency bandwidth can be expanded during rainy weather because the effects of interference and interference are small, and they autonomously expand the frequency bandwidth.

[0052] As described above, in the wireless communication system according to the third embodiment, each of the radio stations A, B, and C observes the spectrum of the surrounding frequencies of the frequency being used and determines whether or not the frequency bandwidth can be expanded based on the observation results of the surrounding frequency spectrum. This makes it possible to operate radio stations A, B, and C autonomously and in a distributed manner, while avoiding interference between the radio signals of radio stations A, B, and C with high precision, and enabling frequency sharing with improved frequency utilization efficiency.

[0053] Although 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 many other embodiments, and various modifications such as omissions and substitutions can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention as described herein, and are included in the scope of the invention and its equivalents as described in the claims.

[0054] Furthermore, the present invention can be provided not only as the devices described above or as systems composed of such devices, but also as methods executed by these devices, programs for a processor to realize the functions of these devices, and storage media for storing such programs in a computer-readable manner. [Industrial applicability]

[0055] This invention can be used in a wireless communication system that includes wireless stations that transmit and receive signals between opposing wireless devices. [Explanation of Symbols]

[0056] a: Main station, b: Substation, 11a,11b: Modulation unit, 12a,12b: Transmitting RF unit, 13a,13b: TDD switch, 14a,14b: Antenna, 15a,15b: Receiving RF unit, 16a,16b: Demodulation unit, 17a,17b: Memory, 18a,18b: RSSI unit, 19a,19b: Correlation calculation unit, 20a,20b: Precipitation estimation unit, 21a,21b: Communication parameter control unit, 30: Propagation path, 31a,31b: Power map generation unit, 41a,41b: Interference wave measurement unit, A,B,C: Radio stations, D: Centralized control station

Claims

1. In a wireless communication system equipped with radio stations that transmit and receive signals between opposing radios, A wireless communication system characterized in that each radio stores a portion of the transmission signal to an opposing radio as a known signal in memory, estimates the precipitation conditions in the propagation path based on the result of a correlation calculation between the known signal and the reflected signal reflected by the transmission signal in the propagation path between the opposing radio, and changes the frequency bandwidth according to the estimated result of the precipitation conditions in the propagation path.

2. In the wireless communication system according to claim 1, A wireless communication system characterized in that each radio has a filter configured to extract frequency components with high temporal variation caused by precipitation, the high-pass filter is applied to the result of the correlation calculation for each frame, and the result is used as a precipitation profile to estimate the precipitation conditions along the propagation path.

3. In the wireless communication system according to claim 1, A wireless communication system characterized in that each wireless device calculates the power intensity of the reflected signal, compares the amount of radio wave attenuation estimated from the estimated precipitation conditions of the propagation path with the amount of radio wave attenuation calculated from the power intensity of the reflected signal, and determines the necessity of changing the frequency bandwidth.

4. In the wireless communication system according to any one of claims 1 to 3, Equipped with a centralized control station that centrally manages multiple radio stations, A wireless communication system characterized in that the centralized control station aggregates the estimated precipitation conditions along the propagation path from each radio station and controls the change in the frequency bandwidth of each radio station based on the estimated precipitation conditions along the propagation path from each radio station.

5. In the wireless communication system according to any one of claims 1 to 3, A wireless communication system characterized in that each wireless device observes the spectrum of the surrounding frequencies of the operating frequency and determines whether or not the frequency bandwidth can be expanded based on the observation results of the spectrum of the surrounding frequencies.

6. In a radio that transmits and receives signals between opposing radios, A radio characterized by storing a portion of the transmission signal to the opposing radio as a known signal in memory, estimating the precipitation conditions in the propagation path based on the result of a correlation calculation between the reflected signal, which is reflected in the propagation path between the transmission signal and the opposing radio, and the known signal, and changing the frequency bandwidth according to the estimated result of the precipitation conditions in the propagation path.

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