Method of wireless communication between a shore base station based on a marine ship-shore channel and a ship

Abstract

The application provides a wireless communication method between a shore base station and a ship based on a marine ship-shore channel. The method comprises constructing a three-dimensional model of the marine ship-shore channel, the model comprising a shore base station as a transmitting end, a ship in a moving state as a receiving end, a hemisphere around the shore base station and a cylinder around the ship, comprehensively considering the influences of scattering around the shore base station and the ship, reflection of the sea level and rolling motion of the ship, calculating time-varying distances according to geometric relations of the model to obtain an impulse response of the channel; and obtaining a space-time-frequency correlation function and a Doppler power spectral density of the marine channel under the condition of rolling motion of the ship according to the impulse response of the channel. The method accurately describes non-stationary statistical characteristics of the marine channel, is beneficial to studying influences of the rolling motion of the ship on the marine wireless channel and provides theoretical support for establishing a marine wireless communication system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of marine wireless channel modeling, and particularly relates to a wireless communication method between a shore base station and a ship based on a marine ship-shore channel. BACKGROUND

[0002] In recent years, with the promotion of the marine power and the construction of the "intelligent ocean" project, the modern fishery, marine observation and monitoring, marine oil and gas exploration and development, marine transportation and other fields have achieved rapid development. With the increasing frequency of marine activities, it is particularly important to realize seamless, efficient and reliable communication coverage in the sea area. The wireless channel is an important basic problem in the design of wireless communication system, and has great practical significance and value for the design and evaluation of marine mobile communication system. Therefore, establishing an accurate marine ship-shore channel model is a basic prerequisite for improving the performance and reliability of marine communication system.

[0003] At present, there are a large number of studies on marine wireless channel modeling, involving ship-to-shore, ship-to-ship, marine unmanned aerial vehicle and other communication scenarios. However, most of the current geometric-based marine ship-shore channel models ignore the roll motion of the ship under the influence of sea waves, and the research on the marine ship-shore channel model considering the roll of the ship mostly focuses on the influence of the roll of the ship on the antenna gain, and there is still a lack of research on the statistical characteristics of the channel. Therefore, how to effectively establish a marine geometric channel model considering the roll of the ship is a problem to be solved. SUMMARY

[0004] Embodiments of the present application provide a wireless communication method between a shore base station and a ship based on a marine ship-shore channel, to effectively study the influence of the roll of the ship on the marine wireless channel and provide theoretical support for establishing a marine wireless communication system.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme.

[0006] A wireless communication method between a shore base station and a ship based on a marine ship-shore channel, comprising:

[0007] constructing a three-dimensional model of the marine ship-shore channel, the three-dimensional model of the marine ship-shore channel comprising a shore base station as a transmitting end, a ship in a moving state as a receiving end, a hemisphere located around the shore base station and a cylinder located around the ship;

[0008] introducing a sinusoidal random process to describe the roll motion of the ship under the action of sea waves, and obtaining the influence of the roll motion on the receiving antenna of the ship;

[0009] establishing a channel impulse response of the marine ship-shore channel according to the influence of the roll motion on the receiving antenna of the ship and different propagation paths of the signal scattered by the scatterer.

[0010] According to the geometric relationship among the transmitting end, the receiving end and the scatterers, time-varying transmission distance and time-varying angle of the marine ship-shore channel caused by the ship movement and the roll motion are derived;

[0011] According to the channel impulse response, the time-varying transmission distance and the time-varying angle, the space-time-frequency correlation function and the Doppler power spectral density channel characteristics of the marine ship-shore channel are obtained, and the ship and the shore base station use the channel characteristics of the marine ship-shore channel for wireless communication.

[0012] Preferably, the three-dimensional model of the marine ship-shore channel assumes that there are N1 scatterers distributed on the surface of a hemisphere composed of L different radius R l The nth1 effective scatterer on the lth circle is represented as It is assumed that there are N2 scatterers distributed on the surface of a cylinder with a radius R r The nth2 effective scatterer on the cylinder surface is represented as

[0013] The height of the transmitting end is H T , and it is equipped with L T antennas; the height of the receiving end is H R , and it is equipped with L R antennas; the movement of the ship is characterized by the horizontal velocity v R and the azimuth angle γ R of the velocity; the initial distance between the shore base station and the ship is D.

[0014] Preferably, the roll motion of the ship caused by the sea waves is described by introducing a sinusoidal random process, and the influence of the roll motion on the receiving antenna of the ship is obtained, including:

[0015] The marine ship-shore channel is described by using an L T × L R antenna array; the azimuth angle and the elevation angle of the transmitting end antenna array are θ T and ψ T respectively; the azimuth angle and the elevation angle of the receiving end antenna array are θ R and ψ R respectively.

[0016] The roll motion of the ship caused by the sea waves is described by introducing a sinusoidal random process, and the elevation angle of the receiving end antenna array satisfies:

[0017]

[0018] wherein ψ R (t0) represents the elevation angle of the receiving end antenna array at the initial time t0.​ denotes the maximum roll angle of the ship, i.e. the roll amplitude, and T denotes the roll period.

[0019] Preferably, the channel impulse response of the maritime channel is established based on the influence of the roll motion on the ship receiving antennas and the different propagation paths of the signal via scatterers, comprising:

[0020] The channel impulse response of the maritime channel from the p-th transmitting antenna on the shore transmitting end to the q-th receiving antenna on the ship receiving end is determined as:

[0021]

[0022] wherein, and denote the channel impulse responses of the LOS path, the Ref path, the SB1 path and the SB2 path, respectively;

[0023] The different propagation paths of the signal comprise the LOS path, the Ref path, the SB1 path and the SB2 path, wherein the LOS path is the direct propagation of the signal from the shore transmitting end to the ship receiving end, the Ref path is the propagation of the signal from the shore transmitting end to the ship receiving end via the sea surface mirror reflection, the SB1 path is the propagation of the signal from the shore transmitting end to the ship receiving end via the scatterers on the surface of the half-sphere after scattering, and the SB2 path is the propagation of the signal from the shore transmitting end to the ship receiving end via the scatterers on the surface of the cylinder after scattering;

[0024] The channel impulse responses of the path components are calculated, and the specific expression is:

[0025] The channel impulse response of the LOS path is:

[0026]

[0027] wherein, t represents the time variable, τ represents the time delay variable, δ(τ-τ LOS ) represents the additional time delay term, f D,LOS represents the Doppler shift of the LOS path, d LOS (t) represents the propagation distance of the signal in the LOS path; the channel impulse response of the Ref path is:

[0028]

[0029] wherein, d Ref (t) represents the propagation distance of the signal in the Ref path;

[0030] The channel impulse response of the SB1 path is:

[0031]

[0032] where d SB1 (t) denotes the propagation distance of the signal in the SB1 path;

[0033] The channel impulse response of the SB2 path is:

[0034]

[0035] where d SB2 (t) denotes the propagation distance of the signal in the SB2 path;

[0036] where f c denotes the carrier frequency, c denotes the speed of light, K denotes the Rician factor, and η Ref , η SB1 , and η SB2 denote the proportions of the Ref component, the SB1 component, and the SB2 component in the scattering power 1 / (K+1), respectively, which satisfy η Ref + η SB1 + η SB2 = 1; random phase offsets φ Ref , and are mutually independent and uniformly distributed in [— π, π) with equal probability;

[0037] τ LOS , τ Ref , τ SB1 , and τ SB2 represent the propagation delays of the LOS path, the Ref path, the SB1 path, and the SB2 path, respectively, which are expressed as:

[0038]

[0039]

[0040] f D,LOS , f D,Ref , f D,SB1 , and f D,SB2 represent the Doppler shifts of the LOS path, the Ref path, the SB1 path, and the SB2 path, respectively, which are expressed as:

[0041]

[0042] where λ denotes the wavelength of the light wave, and denote the arrival azimuth, the arrival elevation, and the departure elevation of the LOS path, respectively, and denote the arrival azimuth, the arrival elevation, and the departure elevation of the Ref path, respectively, and denote the departure azimuth and departure elevation angle of the SB1 path, respectively, and denote the arrival azimuth and arrival elevation angle of the SB1 path, respectively; and denote the arrival azimuth, arrival elevation and departure elevation angle of the SB2 path, respectively.

[0043] Preferably, the deriving the time-varying transmission distance and time-varying angle of the marine ship-to-shore channel due to the ship movement and roll motion according to the geometric relationship among the transmitting end, receiving end and scatterer comprises:

[0044] The distance formula of the signal propagating from the pth transmitting antenna of the shore transmitting end to the qth receiving antenna of the ship receiving end is:

[0045]

[0046] The distance formula of the signal propagating from the pth transmitting antenna of the shore transmitting end to the qth receiving antenna of the ship receiving end via the sea surface mirror reflection is:

[0047]

[0048] The distance formula of the signal propagating from the pth transmitting antenna of the shore transmitting end to the scatterer is:

[0049]

[0050] The distance formula of the signal propagating from the scatterer to the qth receiving antenna of the ship receiving end is:

[0051]

[0052] The distance formula of the signal propagating from the pth transmitting antenna of the shore transmitting end to the scatterer is:

[0053]

[0054] The distance formula of the signal propagating from the scatterer to the qth receiving antenna of the ship receiving end is:

[0055]

[0056] wherein θ T and θ R are the horizontal azimuth angles of the transmitting end and receiving end antenna arrays, respectively, and ψ Tdenote the departure azimuth and departure elevation of the SB1 path, respectively; and denote the departure azimuth and departure elevation of the SB1 path, respectively;

[0057] Δ T denote the distance from the p-th transmit antenna to the center of the transmit antenna array, Δ R denote the distance from the q-th receive antenna to the center of the receive antenna array, which satisfy:

[0058]

[0059] d T and d R denote the antenna spacing of the transmit end and the receive end, respectively;

[0060] Further, the time-varying angles of each path component are as follows:

[0061] In the LOS path:

[0062] In the Ref path:

[0063] In the SB1 path:

[0064]

[0065] In the SB2 path:

[0066]

[0067] In the marine ship-to-shore channel model, the number of effective scatterers is assumed to be infinite, the discrete azimuth elevation and radius R l are replaced by continuous random variables and R, assuming that the azimuth and are independent, and their distributions are described by von Mises distribution:

[0068]

[0069] where I0(·) is the first-order zero Bessel function, α μ ∈[-π,π) is the average value of the azimuth α; k (k≥0) represents the concentration of the azimuth;

[0070] the elevation and are represented by cosine distribution:

[0071]

[0072] where β m denotes the maximum value of the elevation angle, β μ denotes the average value of the elevation angle.

[0073] The radius of the circle on the hemisphere is described by the following probability density function:

[0074]

[0075] where R1 and R2 denote the minimum and maximum values of the radius, respectively.

[0076] Preferably, the step of obtaining the space-time-frequency correlation function and the Doppler power spectral density of the marine ship-to-shore channel according to the channel impulse response, the time-varying transmission distance and the time-varying angle comprises:

[0077] The step of calculating the space-time-frequency correlation function of the marine ship-to-shore channel comprises:

[0078]

[0079] where E(·) denotes the expectation operation, (·) * denotes the complex conjugate operation;

[0080] The formula of the LOS path is specifically:

[0081]

[0082] The formula of the Ref path is specifically:

[0083]

[0084] The formula of the SB1 path is specifically:

[0085]

[0086] The formula of the SB2 path is specifically:

[0087]

[0088] The Doppler power spectral density of the marine ship-to-shore channel is obtained by performing Fourier transform on the time correlation function, and the specific expression is:

[0089]

[0090] where f D denotes the Doppler frequency, and the Doppler power spectral density of the channel is the superposition of the Doppler power spectral densities of the LOS path, the Ref path, the SB1 path and the SB2 path.

[0091] The technical solution provided by the embodiment of the application can be seen as follows: the method accurately describes the non-stationary statistical characteristics of the marine channel, is beneficial to the research on the influence of ship roll on the marine wireless channel, and provides theoretical support for the establishment of the marine wireless communication system.

[0092] Additional aspects and advantages of the application will be described in the following description, will become apparent from the following description, or will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0093] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0094] Figure 1 A processing flow chart of a wireless communication method between a shore base station and a ship based on a marine ship-shore channel is provided for the embodiment of the application.

[0095] Figure 2 A marine ship-shore channel model based on geometry is provided for the embodiment of the application.

[0096] Figure 3 A ship roll motion diagram is provided for the embodiment of the application.

[0097] Figure 4 A three-dimensional time-varying time correlation function of the marine ship-shore channel is provided for the embodiment of the application.

[0098] Figure 5 A time correlation function of the marine ship-shore channel at different times is provided for the embodiment of the application.

[0099] Figure 6 A normalized Doppler power spectrum of the marine ship-shore channel is provided for the embodiment of the application.

[0100] Figure 7 A Doppler power spectrum under different ship motion directions is provided for the embodiment of the application. DETAILED DESCRIPTION

[0101] The embodiments of the application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the application, and cannot be explained as a limitation of the application.

[0102] Those skilled in the art can understand that the singular forms "a," "an," and "the" used herein include plural references unless expressly stated to the contrary. It should be further understood that the word "comprise" used in the specification of the application means that the features, integers, steps, operations, elements, and / or components listed thereafter exist, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can be an intermediate element. In addition, "connected" or "coupled" used herein can include wireless connection or coupling. The phrase "and / or" used herein includes any one of the associated listed items and all combinations of the associated listed items.

[0103] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as that generally understood by those skilled in the art to which the present application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as such.

[0104] For the convenience of understanding the embodiments of the present application, the following will be further explained with several specific embodiments as examples in conjunction with the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present application.

[0105] The processing flow of a wireless communication method between a shore base station and a ship based on a marine ship-shore channel provided by the embodiments of the present application is shown in Figure 1 , which includes the following processing steps:

[0106] Step S1: Establish a three-dimensional model of the marine ship-shore channel as shown in Figure 2 , as shown in Figure 2 , the three-dimensional model of the marine ship-shore channel includes a shore base station as a transmitting end, a ship in a moving state as a receiving end, and a hemisphere and a cylinder respectively located around the shore base station and the ship.

[0107] The model assumes that there are N1 scatterers around the transmitting end distributed on the surface of a hemisphere composed of L different circles with radii R l , where the nth1 effective scatterer on the lth circle is represented as It is assumed that there are N2 scatterers near the receiving end distributed on the surface of a cylinder with radius R r , , which represents the nth2 effective scatterer on the cylindrical surface.

[0108] The height of the transmitting end is HT , equipped with L T antennas; the height of the receiving end is H R , equipped with L R antennas, the movement of the ship is characterized by a horizontal velocity v R and an azimuth angle γ R of the velocity; the initial distance between the shore base station and the ship is D.

[0109] Step S2: constructing a model of the ship roll motion as shown in Figure 3 , and obtaining the influence of the roll motion on the ship receiving antennas;

[0110] Step S3: establishing the channel impulse response of the marine ship-shore channel according to the geometric model and the different propagation paths of the signals scattered by the scatterer;

[0111] Step S4: deriving the time-varying transmission distance and time-varying angle of the marine ship-shore channel due to the ship movement and roll motion according to the geometric relationship among the transmitting end, the receiving end and the scatterer;

[0112] Step S5: obtaining the channel characteristics such as the space-time-frequency correlation function and Doppler power spectral density of the marine ship-shore channel according to the channel impulse response. The ship and the shore base station use the channel characteristics of the marine ship-shore channel for wireless communication.

[0113] Further, in step S2, the marine ship-shore channel is described by using an L T ×L R antenna array, the azimuth angle and the elevation angle of the transmitting end antenna array are θ T and ψ T respectively, and the azimuth angle and the elevation angle of the receiving end antenna array are θ R and ψ R respectively.

[0114] A sinusoidal random process is introduced to describe the roll motion of the ship under the action of sea waves, and the elevation angle of the receiving end antenna array satisfies:

[0115]

[0116] wherein ψ R (t0) represents the elevation angle of the receiving end antenna array at the initial time t0, and φ represents the maximum roll angle of the ship, i.e., the roll amplitude, and T represents the roll period.

[0117] Further, in step S3, the channel impulse response of the marine ship-shore channel from the pth transmitting antenna of the shore transmitting end to the qth receiving antenna of the ship receiving end is determined as:

[0118]

[0119] Different signal propagation paths were identified, including the LOS path (signal propagates directly from the shore transmitter to the ship receiver), the Ref path (signal is emitted from the shore transmitter, reflects off a mirror at sea level, and reaches the ship receiver), and the SB1 path (signal is emitted from the shore transmitter, scatters off a surface of a hemispherical object). (After scattering, the signal reaches the ship's receiver), SB2 path (the signal is emitted from the shore transmitter and scatters through the surface of the cylinder). (After scattering, the signal reaches the ship's receiver); calculate the channel impulse response for each path component, the specific expression is:

[0120] The channel impulse response of the LOS path is:

[0121]

[0122] The channel impulse response of the Ref path is:

[0123]

[0124] The channel impulse response of the SB1 path is:

[0125]

[0126] The channel impulse response of the SB2 path is:

[0127]

[0128] Among them, f c Let denot be the carrier frequency, c be the speed of light, K be the Rice factor, and η be the carrier frequency. Ref η SB1 and η SB2 These represent the proportions of the Ref component, SB1 component, and SB2 component to the scattered power 1 / (K+1), respectively, and they satisfy η Ref +η SB1 +η SB2 =1; Random phase offset φ Ref , and They are independent of each other and all follow a uniform distribution on [-π, π);

[0129] τ LOS τ Ref τ SB1 and τ SB2 The propagation delays for the LOS path, Ref path, SB1 path, and SB2 path, respectively, are represented as:

[0130]

[0131] fD,LOS , f D,Ref , f D,SB1 and f D,SB2 represent the Doppler shifts of the LOS path, the Ref path, the SB1 path and the SB2 path, respectively, which are expressed as:

[0132]

[0133] where λ represents the wavelength of the light wave, and represent the azimuth angle of arrival, the elevation angle of arrival and the elevation angle of departure of the LOS path, respectively, and represent the azimuth angle of arrival, the elevation angle of arrival and the elevation angle of departure of the Ref path, respectively, and represent the azimuth angle of departure and the elevation angle of departure of the SB1 path, respectively, and represent the azimuth angle of arrival and the elevation angle of arrival of the SB1 path, respectively; and represent the azimuth angle of arrival, the elevation angle of arrival and the elevation angle of departure of the SB2 path, respectively.

[0134] Further, in step S4, the distance calculation formula of the signal propagating from the pthtransmitting antenna of the transmitting end on the shore to the qthreceiving antenna of the receiving end on the ship is:

[0135]

[0136] The distance calculation formula of the signal propagating from the pthtransmitting antenna of the transmitting end on the shore to the qthreceiving antenna of the receiving end on the ship after the sea surface mirror reflection is:

[0137]

[0138] The distance calculation formula of the signal propagating from the pthtransmitting antenna of the transmitting end on the shore to the scattering body is:

[0139]

[0140] The distance calculation formula of the signal propagating from the scattering body to the qthreceiving antenna of the receiving end on the ship is:

[0141]

[0142] The distance calculation formula of the signal propagating from the pthtransmitting antenna of the transmitting end on the shore to the scattering body is:

[0143]

[0144] signal from scatterer The distance from the scatterer to the qth receiving antenna of the ship receiving end is calculated as:

[0145]

[0146] where θ T and θ R are the azimuth angles of the transmitting and receiving antenna arrays, respectively, ψ T is the elevation angle of the transmitting antenna array, and denote the departure azimuth and departure elevation of the SB1 path, respectively;

[0147] Δ T denotes the distance from the pth transmitting antenna to the center of the transmitting antenna array, Δ R denotes the distance from the qth receiving antenna to the center of the receiving antenna array, which satisfy:

[0148]

[0149] d T and d R denote the antenna spacing of the transmitting and receiving ends, respectively;

[0150] Further, the time-varying angles of each path component are as follows:

[0151] In the LOS path:

[0152] In the Ref path:

[0153] In the SB1 path:

[0154]

[0155] In the SB2 path:

[0156]

[0157] In the marine ship-to-shore channel model, the number of effective scatterers is assumed to be infinite, so the discrete azimuth elevation and radius R l in the model can be replaced by continuous random variables and R. Assuming that the azimuth and are independent, their distributions can be described by von Mises distribution:

[0158]

[0159] where I0(·) is the first kind zero order Bessel function; a μ is the average value of azimuth angle a; k (k≥0) represents the concentration degree of azimuth angle.

[0160] pitch angle and The distribution of can be represented by a cosine distribution:

[0161]

[0162] where β m represents the maximum value of elevation angle, and β μ represents the average value of elevation angle.

[0163] The radius of the circle on the hemisphere can be described by the following probability density function:

[0164]

[0165] where R1 and R2 represent the minimum and maximum values of the radius, respectively.

[0166] Further, in step S5, the calculation step of the space-time-frequency correlation function of the marine ship-shore channel is:

[0167]

[0168] where E(·) represents the expectation operation, and (·) * represents the complex conjugate operation;

[0169] The formula of the LOS path is specifically represented as:

[0170]

[0171] The formula of the Ref path is specifically represented as:

[0172]

[0173] The formula of the SB1 path is specifically represented as:

[0174]

[0175] The formula of the SB2 path is specifically represented as:

[0176]

[0177] Further, the Doppler power spectral density of the marine ship-shore channel is obtained by Fourier transform of the time correlation function, and the specific expression is:

[0178]

[0179] Among them, f D The value represents the Doppler frequency. The Doppler power spectral density of the channel is the superposition of the Doppler power spectral densities of the LOS path, Ref path, SB1 path, and SB2 path.

[0180] Application Example: This invention is used for marine ship-to-shore channel modeling and parameter calculation. The relevant parameter settings are as follows: f c =2GHz, H T =25m, H R =10m, D=5000m, L T =2,L R =2,d T =0.5λ,d R =0.5λ, p=1, q=1, p1=1, q1=2, v R =10m / s, γ R =45°, θ T =θ R =90°, ψ T =20°, ψ R (t0)=0°,k=3,α μ =0°, β m =45°, β μ =45°, R1=0m, R2=50m, R r =40m, K=1, η Ref =0.2, η SB1 =0.4, η SB2 =0.4.

[0181] Figure 4 This paper demonstrates the three-dimensional time-varying time correlation function of a marine ship-to-shore channel model established using the method described in this invention, with a roll period of 4 seconds and a roll amplitude of 10°. Figure 4 As can be seen, the channel correlation changes with time and time intervals, indicating that the model established in this invention can simulate the non-stationarity caused by ship roll in the ocean-to-shore channel in the time domain. Meanwhile, from... Figure 4 As can be observed, the time correlation function is symmetrical about 2s in time. This is because the present invention uses a sinusoidal process to describe the ship's roll motion, which causes the change in the elevation angle of the receiving antenna to have a certain periodicity, thus making the time correlation function obtained from the simulation also show periodic changes.

[0182] Figure 5The time correlation functions of the marine ship-shore channel model established by the method are shown at different times. The roll angles of the ship are 10°, 0° and -10° at t=0s, t=1s and t=2s respectively. As can be seen from the figure, the time correlation of the channel increases with the decrease of the roll angle of the ship, which shows that the ship will affect the time correlation of the channel even if there is a small roll movement. In addition, according to the time correlation function, the coherence time of the channel when the roll angle of the ship is 10°, 0° and -10° is about 8ms, 9ms and 12ms respectively, which shows that the change of the channel is slower when the roll angle is -10°, and the time domain stability is better.

[0183] Figure 6 The Doppler power spectrum of the marine ship-shore channel model established by the method is shown at different times. The experimental results show that the smaller the roll angle of the ship, the greater the change degree of the Doppler power spectrum density of the channel, and the narrower the Doppler power spectrum, which is consistent with the conclusion obtained. Figure 3 This shows that the model established by the application can simulate the influence of the roll of the ship on the Doppler spread in the frequency domain.

[0184] Figure 7 The Doppler power spectrum of the marine ship-shore channel model established by the method is shown at different times. The experimental results show that the smaller the roll angle of the ship, the greater the change degree of the Doppler power spectrum density of the channel, and the narrower the Doppler power spectrum, which is consistent with the conclusion obtained. R R R R This result shows that the Doppler power spectrum of the marine ship-shore channel is related to the movement direction of the ship, so the stability of the channel can be improved by adjusting the appropriate movement direction of the ship.

[0185] In summary, the embodiment of the application proposes a marine ship-shore channel modeling method based on geometry. The model is composed of a three-dimensional hemisphere and a cylinder, and comprehensively considers the influence of the base station on the shore, the scattering around the ship and the reflection of the sea surface, and the roll movement of the ship, which conforms to the actual communication scene. The time-varying distance is calculated according to the geometric relationship of the model, and the impulse response of the channel is obtained. According to the impulse response of the channel, the space-time-frequency correlation function and the Doppler power spectrum density of the marine ship-shore channel under the condition of the roll movement of the ship are obtained, which accurately describes the non-stationary statistical characteristics of the marine ship-shore channel, is conducive to studying the influence of the roll of the ship on the marine wireless channel, and provides theoretical support for establishing a marine wireless communication system.

[0186] ​​​Those skilled in the art can understand that the modules or flows in the drawings are not necessarily required for implementing the present application.

[0187] From the above description of the embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software and necessary universal hardware platforms. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a number of instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in various embodiments or some parts of the embodiments.

[0188] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each of the embodiments focuses on the difference from other embodiments. In particular, the device or system embodiments are described more simply because they are basically similar to the method embodiments, and the relevant parts can be referred to the part of the method embodiments. The above-described device and system embodiments are merely illustrative, and the units described as separate components can be or can not be physically separated, and the components displayed as units can be or can not be physical units, i.e., they can be located in one place or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiments according to the actual needs. Those skilled in the art can understand and implement it without creative labor.

[0189] The above describes only the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought by those skilled in the art without creative labor, and should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of wireless communication between a shore-based base station and a ship based on a marine ship-to-shore channel, the method comprising: The application relates to a method for constructing a three-dimensional model of a marine ship-shore channel. The method comprises the following steps: a sine random process is introduced to describe the rolling motion of a ship under the action of sea waves, and the influence of the rolling motion on a receiving antenna of the ship is obtained; a channel impulse response of the marine ship-shore channel is established according to the influence of the rolling motion on the receiving antenna of the ship and different propagation paths of signals scattered by a scatterer; a time-varying transmission distance and a time-varying angle of the marine ship-shore channel caused by the movement and rolling motion of the ship are derived according to the geometric relationship among a transmitting end, a receiving end and the scatterer; time-frequency correlation functions and Doppler power spectral density channel characteristics of the marine ship-shore channel are obtained according to the channel impulse response, the time-varying transmission distance and the time-varying angle, and the ship and the shore base use the channel characteristics of the marine ship-shore channel for wireless communication.

2. The method of claim 1, wherein, The three-dimensional model of the marine ship-to-shore channel assumes that there are L different radii R distributed around the transmitter. l There are N1 scatterers on the surface of a hemisphere composed of circles. The effective scatterer on the l-th circle is denoted as... Assume there are distributions of radius R near the receiver. r N2 scatterers on the surface of a cylinder, This represents the n2th effective scattering body on the cylindrical surface; The height of the transmitting end is H T , equipped with L T antennas; the height of the receiving end is H R , equipped with L R antennas, the movement of the ship is characterized by the horizontal speed v R and the azimuth angle γ R of the speed; the initial distance between the shore base station and the ship is D.

3. The method of claim 2, wherein, The method comprises the following steps: L T ×L R The antenna array describes the marine ship-shore channel, the horizontal azimuth angle and the elevation angle of the transmitting end antenna array are θ T and ψ T , respectively, and the horizontal azimuth angle and the elevation angle of the receiving end antenna array are θ R and ψ R , respectively. a sine random process is introduced to describe the rolling motion of a ship under the action of sea waves, and the influence of the rolling motion on a receiving antenna of the ship is obtained; wherein ψ R (t0) represents the pitch angle of the receiving antenna array at the initial time t0, denotes the maximum roll angle, i.e. the roll amplitude, of the ship, and T denotes the roll period.

4. The method of claim 3, wherein, the pitch angle of the receiving antenna array of the ship satisfies the following condition: the method comprises the following steps: wherein, and hlos, href, hsb1, and hsb2 represent the channel impulse responses of the LOS path, the Ref path, the SB1 path, and the SB2 path, respectively. The different propagation paths of the signal include an LOS path, a Ref path, an SB1 path and an SB2 path, the LOS path is that the signal is directly propagated from a shore transmitting end to a ship receiving end, the Ref path is that the signal is emitted from the shore transmitting end, reflected by a sea surface mirror and then arrives at the ship receiving end, the SB1 path is that the signal is emitted from the shore transmitting end, scattered by a scattering body S on a surface of a hemisphere and then arrives at the ship receiving end, and the SB2 path is that the signal is emitted from the shore transmitting end, scattered by a scattering body S on a surface of a cylinder (n2) and then arrives at the ship receiving end. the channel impulse response of the marine ship-shore channel is determined according to the influence of the rolling motion on the receiving antenna of the ship and different propagation paths of signals scattered by a scatterer; the channel impulse response of each path component is calculated, and the specific expression is as follows: where t represents the time variable, τ represents the time delay variable, δ(τ - τ LOS ) represents the additional time delay term, f D,LOS represents the Doppler shift of the LOS path, d LOS (t) represents the propagation distance of the signal in the LOS path; the channel impulse response of the Ref path is: where d Ref( t ) represents the propagation distance of the signal in the Ref path; the channel impulse response of the LOS path is as follows: where d SB1( t ) represents the propagation distance of the signal in the SB1 path; the channel impulse response of the SB1 path is as follows: where d SB2( t ) represents the propagation distance of the signal in the SB2 path; where f c denotes the carrier frequency, c denotes the speed of light, K denotes the Rician factor, η Ref , η SB1 , and η SB2 denote the proportions of the Ref component, the SB1 component, and the SB2 component in the scattered power 1 / (K+1), respectively, which satisfy η Ref + η SB1 + η SB2 = 1; random phase offsets φ Ref , and are mutually independent and uniformly distributed on [-π, π). τ LOS , τ Ref , τ SB1 , and τ SB2 represent the propagation delays of the LOS path, the Ref path, the SB1 path, and the SB2 path, respectively, and are expressed as: f D,LOS , f D,Ref , f D,SB1 and f D,SB2 represent the Doppler shifts of the LOS path, the Ref path, the SB1 path and the SB2 path, respectively, which are expressed as: where λ denotes the wavelength of the light wave, and denote the arrival azimuth, the arrival elevation and the departure elevation of the LOS path, respectively, and denote the arrival azimuth, the arrival elevation and the departure elevation of the Ref path, respectively, and denote the departure azimuth and departure elevation angle of the SB1 path, respectively, and denote the arrival azimuth and arrival elevation angle of the SB1 path, respectively; and denote the arrival azimuth, arrival elevation and departure elevation angle of the SB2 path, respectively.

5. The method of claim 4, wherein, the channel impulse response of the SB2 path is as follows: the method comprises the following steps: the distance formula of signals transmitted from a pth transmitting antenna of a shore transmitting end to a qth receiving antenna of a ship receiving end is as follows: The signal is transmitted from the pth transmitting antenna of the transmitting end on the shore to the scatterer The distance calculation formula is: Signal from scatterer The distance from the scatterer to the qth receiving antenna of the ship receiving end is calculated by the following formula: The signal is transmitted from the pth transmitting antenna of the transmitting end on the shore to the scatterer The distance calculation formula is: Signal from scatterer The distance from the scatterer to the qth receiving antenna of the ship receiving end is calculated by the following formula: where θ T and θ R are the azimuth angles of the shore transmitting antenna array and the ship receiving antenna array, respectively, ψ T is the elevation angle of the shore transmitting antenna array, and denote the departure azimuth and departure elevation of the SB1 path, respectively. Δ T represents the distance of the pth transmit antenna from the center of the transmit antenna array, Δ R represents the distance of the qth receive antenna from the center of the receive antenna array, which satisfy: d T and d R denote the antenna spacing between the shore transmitting end and the ship receiving end, respectively; the distance formula of signals transmitted from the pth transmitting antenna of the shore transmitting end to the qth receiving antenna of the ship receiving end after being reflected by a sea surface mirror is as follows: In the LOS path: In the Ref path: moreover, the time-varying angle of each path component is as follows: in the SB1 path: the number of effective scatterers is assumed to be infinite, the SB1 path in the marine ship-to-shore channel model is discrete in departure azimuth the SB2 path in the marine ship-to-shore channel model is discrete in arrival azimuth the SB1 path in the marine ship-to-shore channel model is discrete in departure elevation the SB2 path in the marine ship-to-shore channel model is discrete in arrival elevation and radius R l are replaced by continuous random variables the departure azimuth of the SB1 path is assumed to be uniformly distributed over the arrival azimuth of the SB2 path is assumed to be uniformly distributed over each independently, their distributions are described by von Mises distributions: in the SB2 path: when the distribution describes the distribution of the departure azimuth of the SB1 path , then the α at this time refers to the departure azimuth of the SB1 path α μ ∈[-π,π) is the average value of the departure azimuth of the SB1 path, and k (k≥0) represents the concentration degree of the departure azimuth of the SB1 path; when the distribution describes the distribution of the arrival azimuth of the SB2 path , then the α at this time refers to the arrival azimuth of the SB2 path α μ ∈[-π,π) is the average value of the arrival azimuth of the SB2 path, and k (k≥0) represents the concentration degree of the arrival azimuth of the SB2 path; Departure elevation angle of the SB1 path Arrival elevation angle of the SB2 path The distribution of the departure and arrival elevation angles of the SB1 and SB2 paths is represented by a cosine distribution: pitch angle and The distribution of the azimuth angle is represented by a cosine distribution: where β represents the mean value of the departure elevation angle of the SB1 path; when the distribution describes the arrival elevation angle of the SB2 path β represents the mean value of the departure elevation angle of the SB1 path; when the distribution describes the arrival elevation angle of the SB2 path β m β represents the maximum value of the departure elevation angle of the SB1 path μ β represents the mean value of the departure elevation angle of the SB1 path; when the distribution describes the arrival elevation angle of the SB2 path β represents the mean value of the departure elevation angle of the SB1 path; when the distribution describes the arrival elevation angle of the SB2 path β m β represents the maximum value of the arrival elevation angle of the SB2 path μ β represents the mean value of the arrival elevation angle of the SB2 path wherein I0(·) is a first-order zero Bessel function; the radius of a circle on the hemisphere is described by the following probability density function:

6. The method of claim 5, wherein, wherein R1 and R2 respectively represent the minimum value and the maximum value of the radius. the method comprises the following steps: Where E(·) represents the expectation operation, (·) * The expression indicates that a complex conjugate calculation is being performed, where t represents the time variable, Δt represents the time interval, f represents the frequency, and Δf represents the frequency interval; H indicates that a time-varying transfer function calculation is being performed. the calculation steps of the time-frequency correlation functions of the marine ship-shore channel are as follows: d(·) denotes distance calculation; d p′q′ (t + Δt) represents the distance from the p'th transmitting antenna of the shore transmitting end to the q'th receiving antenna of the ship receiving end in the sub-channel p'→q'; where q' is the q'th receiving antenna; p' is the p'th transmitting antenna; t is a time variable related to signal transmission time, and Δt is a time interval related to signal transmission time; the formula of the LOS path is as follows: wherein, represents the distance of the signal in the sub-channel p'→q' from the p'th transmitting antenna of the transmitting end on the shore to the q'th receiving antenna of the receiving end on the ship after the reflection of the sea surface; wherein t is a time variable related to the signal transmission time, and Δt is a time interval related to the signal transmission time the formula of the Ref path is as follows: in The meaning is: representing the departure azimuth angle of the SB1 path. The minimum value; The meaning is: representing the departure azimuth angle of the SB1 path. The maximum value; The meaning is: representing the departure pitch angle of the SB1 path. The minimum value; The meaning is: representing the departure pitch angle of the SB1 path. The maximum value; This indicates that the signal in subchannel p'→q' propagates from the p'th transmitting antenna at the shore transmitter to the scatterer. The distance; This indicates that the signal in the subchannel p'→q' originates from the scatterer. The distance propagated to the q′-th receiving antenna at the ship's receiving end; the formula of the SB1 path is as follows: the formula of the SB2 path is as follows: in The meaning is: representing the azimuth of arrival of path SB2. The minimum value; The meaning is: representing the azimuth of arrival of path SB2. The maximum value; The meaning is: representing the arrival pitch angle of the SB2 path. The minimum value; The meaning is: representing the arrival pitch angle of the SB2 path. The maximum value; This indicates that the signal propagates from the p′-th transmitting antenna at the shore-based transmitter to the scatterer. The distance; This indicates that the signal in the subchannel p'→q' originates from the scatterer. The distance from the propagation point to the q′-th receiving antenna at the ship's receiver; assume there are antennas distributed near the ship's receiver with a radius of R. r N2 scatterers on the surface of a cylinder, This represents the n2th effective scattering body on the cylindrical surface; The Doppler power spectral density of the marine ship-shore channel is obtained by Fourier transform of the time correlation function, and the specific expression is as follows: where S(·) denotes the Doppler power spectral density computation, f D denotes the Doppler frequency, the Doppler power spectral density of the channel is the superposition of the Doppler power spectral densities of the LOS path, the Ref path, the SB1 path and the SB2 path, p' and p denote the p' and p-th transmit antenna among the transmit antennas of the shore transmitting end L T q' and q are the q' and q-th receive antenna among the receive antennas of the ship receiving end L R q' and q are the q' and q-th receive antenna among the receive antennas of the ship receiving end L

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