Spectrum compensation device

Abstract

The purpose of the present disclosure is to provide a spectrum compensation device capable of compensating for spectral distortion. The spectrum compensation device according to the present disclosure comprises a database in which a plurality of reference spectra obtained by applying mutually different distortions to a known spectrum and a plurality of correction functions for respectively bringing the plurality of reference spectra close to the known spectrum are accumulated. The spectrum compensation device is configured to execute: a process for acquiring a spectrum of a wireless signal that has reached a receiving station from a transmitting station; a process for determining a reference spectrum closest to the acquired spectrum; and a process for compensating for spectral distortion using a correction function corresponding to the determined reference spectrum.

Description

Spectrum Compensation Device

[0001] The present disclosure relates to a spectrum compensation device.

[0002] In communication across the sea, wireless communication may be utilized as a backup for wired communication such as submarine optical cables. It is known that wireless signals propagating over the sea are affected by fading that occurs at sea.

[0003] Patent Document 1 discloses diversity techniques on the transmission side and the reception side in wireless communication between a communication satellite and a ship. By diversity, it is possible to avoid deterioration of communication quality due to fading that occurs at sea.

[0004] Japanese Patent Laid-Open No. 55-141837

[0005] However, there may be cases where fading cannot be sufficiently avoided even with the diversity technique as described above. In such cases, it is necessary to compensate for the distortion of the spectrum that has occurred in the received signal.

[0006] An object of the present disclosure is to provide a spectrum compensation device capable of compensating for spectrum distortion in order to solve the above problems.

[0007] A first aspect of the present disclosure is a spectrum compensation device configured to execute: a process of acquiring a spectrum of a wireless signal that has reached a receiving station from a transmitting station; a process of discriminating a reference spectrum closest to the spectrum; and a process of compensating for the distortion of the spectrum using a compensation function corresponding to the discriminated reference spectrum, the spectrum compensation device comprising a database in which a plurality of reference spectra each having a different distortion from a known spectrum and a plurality of compensation functions for bringing each of the plurality of reference spectra closer to the known spectrum are stored.

[0008] A second embodiment is a spectral compensation device for compensating the spectrum of a radio signal transmitted from a transmitting station to a receiving station via a radio path including a body of water, comprising a database in which a plurality of water surface conditions of the body of water and a compensation function corresponding to each of the water surface conditions are stored, wherein the compensation function is a function that realizes compensation to bring the distortion superimposed on the radio signal under the corresponding water surface condition closer to a known spectrum, and preferably the spectral compensation device is configured to perform the following: acquiring the spectrum of a new radio signal that has reached the receiving station from the transmitting station; acquiring water surface information when the new radio signal has propagated; determining the water surface condition from the database that is closest to the water surface information; and compensating the distortion of the spectrum of the new radio signal using the compensation function corresponding to the determined water surface condition.

[0009] According to a first aspect of this disclosure, the spectral compensation device includes a database containing a plurality of reference spectra, each having a different distortion, and a plurality of correction functions for bringing the distortion of each reference spectrum closer to a known spectrum. The spectral compensation device compensates the spectrum using correction functions corresponding to the distortion superimposed on the radio signal. Therefore, a spectral compensation device capable of compensating for spectral distortion can be provided.

[0010] Furthermore, according to a second embodiment, the spectral compensation device includes a database in which multiple water surface conditions of a body of water and a compensation function corresponding to each of the multiple water surface conditions are stored. As a result, the spectral compensation device can compensate for the spectrum using a compensation function corresponding to the distortion superimposed on the radio signal propagated over the body of water. Therefore, a spectral compensation device capable of compensating for spectral distortion can be provided.

[0011] This figure illustrates the spectrum to be compensated by the spectrum compensation device according to Embodiment 1. This figure illustrates the method of compensating for spectral distortion by the spectrum compensation device according to Embodiment 1. This is an example configuration of a receiving station and a spectrum compensation device 100 built into the receiving station according to Embodiment 1. This figure shows the hardware configuration of the spectrum compensation device according to Embodiment 1. This figure illustrates the spectrum to be compensated by the spectrum compensation device according to Embodiment 2. This figure illustrates the method of compensating for spectral distortion by the spectrum compensation device according to Embodiment 2.

[0012] Embodiments of this disclosure will be described with reference to the drawings. The same or corresponding components will be denoted by the same reference numerals, and repetition of the description may be omitted.

[0013] Embodiment 1 Figure 1 is a diagram illustrating the spectrum to be compensated by the spectrum compensation device 100 according to Embodiment 1. The spectrum compensation device 100 of this disclosure compensates the spectrum of the radio signal 10 that has reached the receiving station 220 from the transmitting station 210. The spectrum is distorted due to the effects of fading that occurred in the radio path.

[0014] Furthermore, the transmitting station 210 in this disclosure also includes a radio relay station that has a receiving function in addition to the transmitting function of the radio signal 10. Similarly, the receiving station 220 also includes a radio relay station that has a transmitting function in addition to the receiving function of the radio signal 10.

[0015] Figure 2 is a diagram illustrating a method for compensating spectral distortion using the spectral compensation device 100 according to Embodiment 1.

[0016] <Database Creation Stage> The spectrum compensation device 100 acquires a reference spectrum 30 from the receiving station 220. The reference spectrum 30 is a spectrum created from the radio signal 10 which has a known spectrum 20. In other words, the reference spectrum 30 is the known spectrum 20 with distortion according to the path conditions superimposed on it.

[0017] Furthermore, the spectral compensation device 100 estimates a transfer function that models fading in the wireless path based on the reference spectrum 30. In addition, the spectral compensation device 100 calculates a correction function 50 based on the transfer function to remove distortion from the reference spectrum 30 and bring it closer to the known spectrum 20.

[0018] To calculate a correction function 50 corresponding to various distortion patterns, the transmitting station 210 and the receiving station 220 exchange radio signals 10 under various path conditions, for example, by changing the measurement date and time. The spectrum compensation device 100 stores in a database 60 a combination of multiple reference spectra 30, each having different distortions corresponding to the path conditions, and the correction function 50 calculated individually from each reference spectrum 30. The various distortion patterns may be patterns with different degrees of distortion, such as large, medium, and small, as shown in Figure 1, or other patterns.

[0019] <Compensation Stage> In the compensation stage, the spectrum compensation device 100 acquires the spectrum of a new radio signal 10 that has arrived at the receiving station 220 from the transmitting station 210 and uses it as the spectrum to be compensated. The spectrum compensation device 100 identifies a correction function 50 to be used to compensate the spectrum to be compensated from the database 60 and compensates the spectrum to be compensated using the identified correction function 50.

[0020] Specifically, first, the spectral compensation device 100 compares the distortion pattern of the spectrum to be compensated with the distortion patterns of multiple reference spectra 30 stored in the database 60. Next, the spectral compensation device 100 identifies the reference spectrum 30 that is closest to the spectrum to be compensated. Furthermore, the spectral compensation device 100 compensates the spectrum to be compensated using the correction function 50 corresponding to the identified reference spectrum 30.

[0021] As described above, the spectral compensation device 100 of this embodiment includes a database 60 in which a plurality of reference spectra 30, each having different distortions corresponding to the path conditions, and a plurality of correction functions 50 for bringing the distortion of each reference spectrum 30 closer to a known spectrum 20 are stored. The spectral compensation device 100 compensates the spectrum using the correction function 50 corresponding to the distortion superimposed on the wireless signal 10. This is expected to improve the spectral distortion.

[0022] Figure 3 shows an example configuration of a receiving station 220 according to Embodiment 1 and a spectral compensation device 100 built into the receiving station 220.

[0023] The antenna 221 of the receiving station 220 receives the radio signal 10 from the transmitting station 210. The RF receiving circuit 222 performs signal processing on the received signal, such as amplification and automatic gain control (AGC). Furthermore, the RF receiving circuit 222 creates a spectrum from the processed received signal. In this disclosure, the spectrum is assumed to be a frequency spectrum, but it is not limited to a time spectrum.

[0024] The spectral compensation device 100 includes a compensation circuit 101 and a storage device 102.

[0025] The compensation circuit 101 receives the spectrum created by the RF receiver circuit 222 as input. If the input spectrum is the reference spectrum 30, the compensation circuit 101 estimates a transfer function that models fading in the radio path based on the reference spectrum 30. Furthermore, the compensation circuit 101 calculates a correction function 50 based on the transfer function to bring the reference spectrum 30 closer to the known spectrum 20. Statistical analysis or machine learning is used in calculating the correction function 50. The compensation circuit 101 associates the reference spectrum 30 with the correction function 50 calculated from the reference spectrum 30 and stores them in the database 60.

[0026] On the other hand, if the input spectrum is a spectrum to be compensated, the compensation circuit 101 identifies an adjustment function 50 to be used to compensate the spectrum from the database 60, and compensates the spectrum using the identified adjustment function 50.

[0027] The storage device 102 stores the database 60. The storage device 102 is a volatile or non-volatile semiconductor memory such as RAM, ROM, or flash memory, or a magnetic disk, flexible disk, optical disk, DVD, etc. The storage device 102 may be located outside the spectrum compensation device 100 as a server or cloud server, as shown in Figure 3.

[0028] Furthermore, the compensation circuit 101 transmits the distortion-reduced spectrum generated by applying compensation to the spectrum to be compensated to the demodulation circuit 223. The demodulation circuit 223 extracts packet data by demodulating the distortion-reduced spectrum.

[0029] The deframing circuit 224 functions as a buffer that stores a certain number of packet data. The deframing circuit 224 arranges the stored packets in the order they were generated at the transmitting station 210 and reassembles the user signal.

[0030] The interface circuit 225 outputs user signals to a higher layer or other devices.

[0031] The control circuit 226 controls the compensation circuit 101 of the spectrum compensation device 100, the demodulation circuit 223 of the receiving station 220, and the deframing circuit 224. The control circuit 226 also performs necessary control on the demodulation circuit 223 when it receives an alarm from the demodulation circuit 223. Furthermore, the control circuit 226 determines whether compensation is necessary for the spectrum created by the RF receiving circuit 222, and if it determines that compensation is necessary, it causes the compensation circuit 101 to perform spectrum compensation.

[0032] Furthermore, when calculating the correction function 50 using machine learning, the compensation circuit 101 further includes a learning model. The compensation circuit 101 trains the learning model to learn the correction function 50 so that the reference spectrum 30 approaches the training data, which is a known spectrum 20 that does not contain the effects of fading. The compensation circuit 101 links the correction function 50 output from the learning model with the reference spectrum 30 that was the basis for the derivation of the correction function 50 and stores them in the database 60. Examples of machine learning methods include, but are not limited to, known methods such as random forest, SVM (Support Vector Machine), K-nearest neighbors, and neural networks.

[0033] Although Figure 3 illustrates the case where the spectrum compensation device 100 is built into the receiving station 220, the spectrum compensation device 100 may also be located outside the receiving station 220.

[0034] Figure 4 shows the hardware configuration of the spectral compensation device 100 according to Embodiment 1. The processing performed by the spectral compensation device 100 may be executed by a program using a computer equipped with a CPU and memory, in which the spectral compensation program is stored. Alternatively, it may be executed by a program using an integrated circuit such as an FPGA (Field Programmable Gate Array). The spectral compensation program may be provided by recording it on a storage medium or by providing it via a network.

[0035] The spectral compensation device 100 has an input unit 40, an output unit 41, a communication unit 42, a CPU (Central Processing Unit, also called a processor) 43, a memory 44, and an HDD (Hard Disk Drive) 45 connected via a bus 46, and functions as a computer. The spectral compensation device 100 is also configured to input and output data to and from a storage medium 47 that can be read by a computer.

[0036] The input unit 40 is, for example, a keyboard and mouse. The output unit 41 is, for example, a display device such as a display.

[0037] The communication unit 42 is, for example, a communication interface that communicates with the receiving station 220.

[0038] Memory 44 refers to volatile or non-volatile semiconductor memory such as RAM, ROM, and flash memory, or magnetic disks, flexible disks, optical disks, and DVDs.

[0039] The CPU 43 controls each component of the spectral compensation device 100 and performs predetermined processing. The memory 44 and HDD 45 are storage devices 102 that store, for example, spectral compensation programs, database 60 data, etc.

[0040] The storage medium 47 is capable of storing a spectral compensation program, etc., that enables the spectral compensation device 100 to perform its functions. The storage medium 47 is a USB (Universal Serial Bus) memory, a CD-ROM (Compact Disc Read Only Memory), etc.

[0041] Note that the architecture of the spectral compensation device 100 is not limited to the example shown in Figure 4.

[0042] As described above, the spectral compensation device 100 of this embodiment includes a database 60 in which a plurality of reference spectra 30, each having different distortions corresponding to the path state, and a plurality of correction functions 50 for bringing the distortion of each reference spectrum 30 closer to a known spectrum 20 are stored. The spectral compensation device 100 compensates the spectrum using the correction functions 50 corresponding to the distortion superimposed on the wireless signal 10. This makes it possible to provide a spectral compensation device 100 that can compensate for spectral distortion.

[0043] Note that in the above description, it has been explained that the reference spectrum 30 is a spectrum created from the radio signal 10 having the known spectrum 20 that has reached the receiving station 220 from the transmitting station 210. However, the reference spectrum 30 does not necessarily have to be actually created from the radio signal 10 that has reached the receiving station 220 from the transmitting station 210. For example, the distortion superimposed on the radio signal 10 under various path conditions may be modeled respectively, and a plurality of reference spectra 30 may be created by applying different distortions to the known spectrum 20.

[0044] Embodiment 2 Hereinafter, the points of change from Embodiment 1 will be described.

[0045] FIG. 5 is a diagram for explaining the spectrum to be compensated by the spectrum compensation device 100 according to Embodiment 2. In this embodiment, the radio path between the transmitting station 210 and the receiving station 220 includes a water area. Therefore, the radio signal 10 reaching the receiving station 220 has distortion due to fading such as reflected waves and diffracted waves from the water surface 70 superimposed thereon. The water area refers to the sea, rivers, lakes, etc.

[0046] The spectrum compensation device 100 is capable of acquiring data on the water surface state of the water area. The water surface state includes the water level, wave height and period, and if the water area is the sea, the direction of the ocean current, etc., and may also be an imaging image of the water surface 70. The data on the water surface state may further include the generation date and time of the data, and the meteorological information (wind speed, air temperature, etc.) at the time of generation.

[0047] FIG. 6 is a diagram for explaining the method of compensating for the distortion of the spectrum by the spectrum compensation device 100 according to Embodiment 2.

[0048] <Database Creation Stage> In this embodiment, the transmitting station 210 and the receiving station 220 exchange the wireless signal 10 under a plurality of water surface conditions, for example, by changing the measurement date and time. The spectrum compensation device 100 individually calculates the compensation function 50 from a plurality of reference spectra 30 each having different distortions corresponding to the water surface conditions. The spectrum compensation device 100 associates a plurality of water surface conditions with the compensation function 50 corresponding to each of the plurality of water surface conditions and stores them in the database 60. Note that the plurality of water surface conditions may be different states such as large, medium, and small roughness of the water surface 70 as shown in FIG. 6, or other states.

[0049] <Compensation Stage> In the compensation stage, the spectrum compensation device 100 acquires the spectrum of a new wireless signal 10 that has reached the receiving station 220 from the transmitting station 210 and uses it as the spectrum to be compensated. Further, the spectrum compensation device 100 of this embodiment acquires the water surface information when the wireless signal 10 on which the spectrum to be compensated is based propagates. The water surface information is information indicating the water level, wave height and period, and the direction of the ocean current if the water area is the sea, and may be an imaging image of the water surface 70. It is assumed that the water surface information is the same index as the water surface state stored in the database 60, but it may be different.

[0050] The spectrum compensation device 100 determines the compensation function 50 to be used for compensating the spectrum to be compensated from the database 60, and compensates the spectrum to be compensated using the determined compensation function 50.

[0051] Specifically, first, the spectrum compensation device 100 determines the water surface state closest to the water surface information when the wireless signal 10 on which the spectrum to be compensated is based propagates from among the plurality of water surface states stored in the database 60. Further, the spectrum compensation device 100 compensates the spectrum to be compensated using the compensation function 50 corresponding to the determined water surface state.

[0052] As described above, the spectral compensation device 100 of this embodiment includes a database 60 in which multiple water surface conditions of a body of water and a correction function 50 corresponding to each of the multiple water surface conditions are stored. The spectral compensation device 100 compensates the spectrum using a correction function 50 corresponding to the distortion superimposed on the wireless signal 10 propagated over the body of water. This is expected to improve the spectral distortion.

[0053] As described above, this disclosure provides a spectral compensation device 100 that can compensate for spectral distortion.

[0054] This disclosure is not limited to the embodiments described above, and various modifications can be made during implementation without departing from its essence. Furthermore, each embodiment and its modifications may be combined as appropriate, and the combined effects can be obtained in such cases.

[0055] 10: Radio signal, 20: Known spectrum, 30: Reference spectrum, 40: Input section, 41: Output section, 42: Communication section, 43: CPU, 44: Memory, 45: HDD, 46: Bus, 47: Storage medium, 50: Correction function, 60: Database, 70: Water surface, 100: Spectrum compensation device, 101: Compensation circuit, 102: Storage device, 210: Transmitting station, 220: Receiving station, 221: Antenna, 222: RF receiving circuit, 223: Demodulation circuit, 224: Deframing circuit, 225: Interface circuit, 226: Control circuit

Claims

1. A spectrum compensation device comprising a database containing multiple reference spectra, each with a different distortion applied to a known spectrum, and multiple correction functions for bringing each of the multiple reference spectra closer to the known spectrum, and configured to perform the following: acquiring the spectrum of a radio signal that has reached a receiving station from a transmitting station; determining the reference spectrum that is closest to the spectrum; and compensating for the distortion of the spectrum using the correction function corresponding to the determined reference spectrum.

2. The spectral compensation device according to claim 1, configured to perform the following steps during the database creation stage: calculating an individual correction function corresponding to each of the plurality of reference spectra; and linking the plurality of reference spectra and the correction function corresponding to each reference spectrum and storing them in the database.

3. A spectral compensation device for compensating the spectrum of a radio signal transmitted from a transmitting station to a receiving station via a radio path including a body of water, comprising a database in which a plurality of water surface conditions of the body of water and a compensation function corresponding to each of the water surface conditions are stored, wherein the compensation function is a function that realizes compensation to bring the distortion superimposed on the radio signal under the corresponding water surface condition closer to a known spectrum, and the spectral compensation device is configured to perform the following: acquiring the spectrum of a new radio signal that has reached the receiving station from the transmitting station; acquiring water surface information when the new radio signal has propagated; determining the water surface condition from the database that is closest to the water surface information; and compensating the distortion of the spectrum of the new radio signal using the compensation function corresponding to the determined water surface condition.

4. The spectral compensation device according to claim 3, configured to perform the following steps during the database creation stage: a process of individually calculating a compensation function from the spectrum of a wireless signal corresponding to each of the multiple water surface states; and a process of linking the multiple water surface states and the compensation function corresponding to each water surface state and storing them in the database.

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