The present disclosure relates to a method for pervasively modeling 6G channels for all frequency bands and all scenarios, which belongs to the technical field of wireless communication.
As illustrated in
In terms of the all spectra, due to the application of high frequency bands such as mmWave and THz, wireless channels exhibit the characteristics such as wide bandwidth, frequency non-stationarity, diffuse scattering, large path loss, blockage effects and atmosphere absorption. In the visible light communication (VLC) band, the channels will no longer have small-scale fading, and exhibit negligible Doppler effect and frequency non-stationarity. In terms of global-coverage scenarios, in addition to the terrestrial mobile communication scenario, satellite communication, UAV communication and maritime communication scenarios are also included. In the satellite communication channels, the Doppler shift caused by the rapid movement of satellites, the rain attenuation and the ionospheric effect should be taken into account. In the UAV communication system, the arbitrary three-dimensional (3D) trajectories of UAV and altitudes-dependent large-scale parameters should be mainly considered. In terms of the full-application scenarios, the V2V channels exhibit Doppler shift and time-domain non-stationary characteristics due to the multiple mobility of the transceiver and the clusters. At higher moving speeds of more than 500 km/h, the channel experiences stronger Doppler shifts and more pronounced time-domain non-stationarity. In the scenario of ultra-high speed train (UHST) running in vacuum tube, the influence of vacuum tube waveguide effect should also be considered. The ultra-massive MIMO channel exhibits spherical wavefront and spatial non-stationary characteristics. Ultra-dense scatterer distribution and multiple mobility need to be considered in IIoT channels. In addition, the precise modeling for wireless channels utilizing RIS technology also needs to be studied.
Considering that the mixed application of various new technologies will bring about the combination of different channel characteristics, an important challenge of modeling 6G channels is how the various channel characteristics be considered comprehensively and to propose a pervasive channel model suitable for all frequency bands and all scenarios. For example, when mm Wave/THz band and massive MIMO technology are applied at the same time in high-speed moving scenarios, wireless channels will exhibit spatial-time-frequency non-stationary characteristics, spatial consistency (that is, in multi-user scenarios, channel coefficients of neighborhood users are correlated or different trajectory points of a single user are spatially correlated), and multi-band correlation.
To sum up, it is urgent to establish an accurate, pervasive, and flexible 6G channel model. The problems are tried to be solved in standard 5G channel models such as B5GCM, 3GPP TR 38.901, IMT-2020 and QuaDRiGa, but all of them cannot accurately and comprehensively describe all of the above-mentioned characteristics. In terms of the all spectra, these models do not apply to the VLC band, and ignore some characteristics of the mmWave/THz band. For example, QuaDRiGa neglects to model the atmospheric absorption and blockage effects, and 3GPP TR 38.901 and IMT-2020 neglects the frequency non-stationary characteristics of high frequency bands. In terms of all coverage, these channel models are aimed at land mobile communication channels, and cannot be applied to the scenarios of satellite, UAV and maritime communication. In terms of full application, they do not support modeling for HST, UHST, RIS, and IIoT channels, and the spherical wavefront and spatial non-stationary properties of (ultra-)massive MIMO are not taken into consideration in 3GPP TR 38.901 and IMT-2020. In summary, these models still lack pervasiveness and do not take all the channel characteristics mentioned above into consideration. In order to fill the research gap, the pervasive channel modeling theory is proposed and applied to the geometric random channel model, and a modeling method for 6G pervasive channels suitable for all frequency bands and all scenarios is proposed and disclosed.
Technical problems: the objectives of the present disclosure are to provide a method for pervasively modeling 6G channels for all spectra (sub-6 GHz/mmWave/THz/optical wireless frequency bands), global-coverage scenarios (space-air-ground-sea integration, including the communication channels of satellites, UAV, terrestrial and maritime) and full-application scenarios (such as V2V, HST, UHST, (ultra-)massive MIMO, RIS, IIoT scenarios).
Technical solutions: the present disclosure provides a method for pervasively modeling 6G channels for all frequency bands and all scenarios. Massive uniform linear arrays are adopted at both a transmitter side and a receiver side in a 6G pervasive geometry-based stochastic channel model named 6G pervasive channel model (6GPCM), and the model is a multi-bounce propagation model, where ApT denotes a p-th array element of a transmitter antenna array, AqR denotes a q-th array element of a receiver antenna array, and a distance between the transmitter antenna array and the receiver antenna array is δT(δR); βAT(R) denotes an azimuth angle of the transmitter antenna array and the receiver antenna array in an xy plane, and βET(R) denotes an elevation angle of the transmitter antenna array and the receiver antenna array; for a n-th propagation path from ApT to AqR, n=1, 2, 3, . . . , Nqp(t), where CnA denotes a first-bounce cluster of the n-th path proximity to the transmitter side, CnZ denotes a last-bounce cluster proximity to the receiver side, and a propagation path between the two clusters is modeled as a virtual link; when a delay of the virtual link between the first-bounce cluster and the last-bounce cluster is zero, the model is reduced to a single-bounce model; besides, Nqp(t) is the number of paths from ApT to AqR at a time instant/corresponding to Nqp(t) cluster pairs in a double-cluster model with the first-bounce cluster and the last-bounce cluster in one-to-one correspondence with each other, and corresponding to Nqp(t) clusters in a single-cluster model; on a microscopic level, analyzing clusters CnA and CnZ on the n-th path, and Mn(t) scatterers are existed in the clusters, Cm
A channel matrix of the 6GPCM is represented as:
where PL, SH, BL, WE, AL denote large-scale fadings, PL denotes a path loss, SH denotes a shadowing, BL denotes a blockage loss, AL denotes an atmospheric gas absorption loss, WE denotes a weather effect loss, Hs denotes a small-scale fading channel matrix.
The small-scale fading channel matrix Hs is represented as follows:
where MT denotes the number of antenna elements in the transmitter antenna array, MR denotes the number of antenna elements in the receiver antenna array, hqp,f
where KR(t) denotes a Rice factor, hqp,f
where {*}T denotes a transposition operation, fc denotes a carrier frequency, Fp(q),f
denotes a Faraday rotation angle, a unit of fc in which the Faraday rotation angle is calculated here in GHZ, Pqp,m
{right arrow over (d)}qp(t) denotes a vector distance between the transmitter antenna array ApT and the receiver antenna array AqR at the time instant t, c denotes the speed of light, τqp,m
When the method for pervasively modeling 6G channels is utilized in maritime communication scenarios, a LoS path component and multipath components of both a rough ocean surface and an evaporation duct over a sea surface are modeled as hqp,f
When the method for pervasively modeling 6G channels is utilized in RIS scenarios, channels are divided into a sub-channel HTI from the transmitter side to the RIS, a sub-channel HIR from the RIS to the receiver side and a sub-channel HTR from the transmitter side to the receiver side, the three sub-channels are modeled respectively and a phase shift diagonal matrix Φ is introduced to implement an intelligent control for channel environments, calculation methods of HIR, HTI and HTR are the same as that of Hs merely with different parameter values and different distributions of clusters.
When the method for pervasively modeling 6G channels is utilized for VLC channels, on one hand, wavelengths of optical signals are extremely short, a size of the receiver is commonly multi-million wavelengths, with no rapid signal fading on multi-wavelengths, on another hand, due to an incoherent light emitted by an LED light in a VLC system, the optical signals has no phase information, and no rapid signal fading is caused after a superposition of real-valued multipath signals at the receiver side with an exhibition on a slow-varying shadowing, therefore although a current VLC model representation is a channel impulse response form of a multipath superposition, the representation is essentially a large-scale scale model of modeling PL and SH, that is, Hs=1, PL·SH=hp
When the method for pervasively modeling 6G channels is utilized in multi-link scenarios:
Assuming that the number of base stations is NBS and the number of users is NMS, a channel transmission matrix of a multi-link channel model is represented as a following formula:
HBS
In the method for pervasively modeling 6G channels, detailed steps for generating the channel matrix H are specifically as follows.
In S1, propagation scenarios and conditions are set; a carrier frequency, an antenna type, a layout of the channel and a motion trajectory of the transceiver are determined.
In S2, path loss, shadowing, oxygen absorption and blockage effect loss are generated; the method mainly focuses on a modeling for a small-scale fading, and standard channel models are referable to a calculation the large scale fadings.
In S3, according to positions and motion conditions of the transceiver, large-scale parameters with spatial consistency for a delay spread (DS) and 4 angle spreads are generated.
Except SH, other corresponding large-scale parameters include a delay spread DS, an azimuth spread of arrival (ASA), an azimuth spread of departure (ASD), an elevation spread of arrival (ESA), an elevation spread of departure (ESD), a Rice factor (KR) and a cross-polarization ratio (XPR), a generation of the DS is represented as a following formula:
is composed of transceiver position vectors, PT(t)=(xT(t), yT(t), zT(t)) and PR(t)=(xRt), yR(t), zR(t)) denote a coordinate vector at the transmitter side and a coordinate vector at the receiver side at the time instant t, respectively, and initial values of which are generated according to simulation environments and requirements; XDS(P) denotes a normal distribution variable generated by a sine wave superposition method and following a spatial consistency with a mean value of 0 and a variance of 1, DSμ,f
Generation processes of other large-scale parameters are the same as a generation process of the DS, values for all large-scale parameters with spatial consistency in a logarithm domain can be obtained by multiplying a cross-correlation matrix among the large-scale parameters, after 8 large-scale parameters are generated, subsequently values in the logarithm domain are required to be converted into a linear domain; so that the large-scale parameters of the channel are obtained.
In S4, scatterers following an ellipsoid Gaussian scattering distribution are generated, delays, angles and powers of the clusters are calculated according to geographical location information of the transceiver and the scatterers, and channel coefficients are generated.
In S5, the large-scale parameters and the small-scale parameters are updated according to movements of the transceiver and birth-death processes of the clusters; and new channel coefficients are generated. A space-time-frequency non-stationarity of the model is mainly reflected in two aspects, one is parameters for space-time-frequency variations, and another is birth-death processes of the clusters in a space-time-frequency domain, the number of clusters at the time instant t is calculated as follows:
where Nqp(t) denotes the number of the clusters, Nsurv(t) denotes the number of survived clusters determined by a survived probability Psurv(Δt, Δr, Δf) of the clusters, Nnew(t) denotes the number of newly generated clusters following a Poisson distribution with a mean value E[Nnew(t)], λG is defined as a birth rate of the clusters, λR is defined as a combination rate of the clusters, that is, a death rate.
S4 is specifically as follows.
In S401, positions of the scatterers are obtained by using an ellipsoid Gaussian scattering distribution, the scatterers in n-th cluster centered on (
In S402, in a multi-bounce channel model, delays of sub-paths in the cluster at an initial time instant are calculated by
where {tilde over (τ)}m
{tilde over (d)}m
In S403, in (ultra-)massive MIMO scenarios, a sub-paths power Pqp,m
where Zn denotes a per cluster shadowing term in dB, rτ denotes a delay distribution proportionality factor, ξn(p, q) denotes a two-dimensional spatial lognormal process for simulating smooth power variations over antenna arrays.
In wide bandwidth scenarios, a power value is multiplied by
in a frequency domain by taking frequency domain non-stationary characteristics into account, where γm
In S404, for the survived clusters, small-scale parameters such as the powers and the delays of the sub-paths in the clusters at different time instants are required to be updated, for a trajectory segment at the time instant t1, that is, at a subsequent time instant after the clusters are generated, a coordinate of the p-th transmitter antenna ApT is:
where a coordinate {right arrow over (A)}pT(t0) of the p-th transmitter antenna at the initial time instant is calculated by
a coordinate {right arrow over (C)}m
at the time instant t1. A distance from ApT to Cm
In S5, in order to model a space-time-frequency evolution process of the clusters more accurately, two types of sampling intervals are introduced, one type is a time domain sampling interval Δt, a frequency domain sampling interval Δf and a space domain (array domain) sampling interval Δr, and channel parameters are updated continuously, another type is described by ΔtBD, ΔfBD and ΔrBD that are integer multiples of corresponding Δt, Δf and Δr, and during the birth-death processes and the evolution processes of the clusters occurred at sampling points, survival probabilities of the transmitter side and receiver side clusters along the array axis and time axis are as follows:
denote position differences of a transmitter antenna element and a receiver antenna element on the array axis and the time axis, respectively, DcA and DcS denote scenario-dependent factors on the array axis and the time axis, respectively, a joint survived probability of the transmitter side and receiver side clusters is represented as follows:
P
surv(ΔtBD, δp, δq)=PsurvT(ΔtBD, δp)PsurvR(ΔtBD, δq).
The average number of the newly generated clusters is:
When wide bandwidth scenarios are studied, the birth-death processes of the clusters also exist on a frequency axis, and a survival probability of the clusters on the frequency axis is:
where F(ΔfBD) and Dcf are determined by channel measurements, Dcf denotes a scenario-dependent factor on the frequency axis, in summary, when the birth-death processes of the space-time-frequency domain clusters are taken into account, the survival probability of the clusters is:
P
surv(ΔtBD, ΔrBD, ΔfBD)=PsurvT(ΔtBD, δp)PsurvR(ΔtBD, δq)Psurv(ΔfBD).
The average number of the newly generated clusters is:
In UHST scenarios, by taking account of a waveguide effect and an impact of tube wall roughness on channels in vacuum tube UHST scenarios, the average number of the newly generated clusters is:
where Dqp(t) denotes a linear distance between the transmitter side and the receiver side at the time instant t, D denotes an initial distance between the transmitter side and the receiver side, ρs denotes a scattering coefficient of the tube wall, and ρs
Technical effects: proposed in the present disclosure is a pervasive channel modeling theory, and the theory is applied to the geometry-based stochastic channel model (GBSM). By using the cluster-based geometry-based stochastic channel modeling method and framework, and using the unified channel impulse response expression, the 6G channels characteristics for all frequency bands and all scenarios can be modeled, and a 6GPCM based on the pervasive channel modeling theory is proposed, which is basically suitable for all spectra such as sub-6 GHz, mm Wave, THz and VLC channels, full-coverage scenarios channels such as satellites, UAV and maritime communications, as well as full-application scenarios channels such as ultra-massive MIMO, IIoT, and RIS. Moreover, the 6GPCM can be simplified into a dedicated channel model of specific frequency bands and specific scenarios by adjusting the parameters. 6GPCM is extremely important for 6G channel model standardization, 6G generic theory technology research and system fusion construction.
In order to realize the above objectives, the present disclosure proposes a pervasive channel modeling theory, and proposes a 6GPCM based on the theory. Therefore, the present disclosure mainly includes two parts: the pervasive channel model modeling theory and the 6GPCM construction.
The pervasive channel modeling theory is utilizing a unified channel modeling method and framework, a unified channel impulse response expression, and a comprehensive consideration of the characteristics of 6G channels for all frequency bands and all scenarios, to construct a 6G pervasive channel model that is generally applicable to all frequency bands and scenarios of 6G and that can accurately reflect the channel characteristics of 6G, as illustrated in
The 6GPCM is as illustrated in
A channel matrix of a 6GPCM is represented as:
where PL, SH, BL, WE, AL denote large-scale fading, PL denotes path loss, SH denotes shadowing, BL denotes blockage loss, AL denotes atmospheric gas absorption loss, such as the oxygen absorption loss at the mm Wave band and the molecular absorption loss at the THz band, WE denotes weather effect loss, such as rain attenuation loss in satellite communication scenarios. The present disclosure mainly focuses on the calculation of small-scale fading Hs, and the method is as follows:
where MT denotes the number of antenna elements in the transmitter antenna array, MR denotes the number of antenna elements in the receiver antenna array, hqp,f
where KR(t) denotes a Rice factor, hqp,f
where {*}T denotes a transposition operation, fc denotes a carrier frequency, Fp(q),f
denotes a Faraday rotation angle, the unit of fc in which the Faraday rotation angle is calculated here in GHz, Pqp,m
{right arrow over (d)}qp(t) denotes a vector distance between the transmitter antenna array ApT and the receiver antenna array AqR at the time instant t, c denotes a speed of light, τqp,m
It is worth noting that in maritime communication channel scenarios, the LoS path component and multipath components of both rough ocean surface and evaporation duct over the sea surface are modeled as hqp,f
For VLC channels, on one hand, wavelengths of optical signals are extremely short, a size of the receiver is commonly multi-million wavelengths, with no rapid signal fading rapidly on multi-wavelengths, on another hand, due to an incoherent light emitted by an LED light in a VLC system, the optical signals has no phase information, and no rapid signal fading is caused after a superposition of real-valued multipath signals at the receiver side with an exhibition on a slow-varying shadowing, therefore although a current VLC model representation is a channel impulse response form of a multipath superposition, the representation is essentially a large-scale model of modeling PL and SH, that is,
pH, pV denote the number of rows and the number of columns in an LED array.
When multi-users scenarios are taken into account, assuming that the number of base station is NBS and the number of user is NMS, a channel transmission matrix of a multi-link channel model is represented as a following formula:
HBS
The detailed steps for generating the channel coefficients are specifically as follows.
In S1, propagation scenarios and propagation conditions are set; the carrier frequency, the antenna type, the layout of the transceiver and the motion trajectory of the transceiver are determined.
In S2, the path loss, the shadowing, the oxygen absorption and the large scale fading of blockage effect are generated; the method mainly focuses on a modeling for the small-scale fading, and standard channel models for large scale fading are referable to the calculation of this part.
In S3, according to positions and motion conditions of the transceiver, large-scale parameters with spatial consistency for the DS and 4 angle spreads are generated.
Except SH, other corresponding large-scale parameters include DS, ASA, ASD, ESA, ESD, KR and XPR. The generation method of large-scale parameters is the same. The generation of the DS is taken as an example herein and represented as the following formula:
is composed of transceiver position vectors, PT(t)=(xT(t), yT(t), zT(t)) and PR(t)=(xR(t), yR(t), zR(t)) denote a coordinate vector at the transmitter side and a coordinate vector at the receiver side, respectively, and initial values of which are generated according to simulation environments and requirements; XDS(P) denotes a normal distribution variable generated by the sine wave superposition method and following the spatial consistency with the mean value of 0 and the variance of 1, DSμ,f
All 8 large-scale parameters are independently generated by this method, values for all large-scale parameters with spatial consistency in a logarithm domain can be obtained by multiplying a cross-correlation matrix among the large-scale parameters, subsequently values in the logarithm domain are required to be converted into a linear domain; so that the large-scale parameters of the channel are obtained.
In S4, scatterers following an ellipsoid Gaussian scattering distribution are generated, delays, angles and powers of the clusters are calculated according to geographical location information of the transceiver and the scatterers, and channel coefficients are generated.
In S401, positions of the scatterers are obtained by using an ellipsoid Gaussian scattering distribution, the scatterers in the n-th cluster centered on (
In S402, in the multi-bounce channel model, delays of sub-paths in the cluster at the initial time instant are calculated by
where {tilde over (τ)}m
{tilde over (d)}m
In S403, in (ultra-)massive MIMO scenarios, a sub-paths power Pqp,m
where Zn denotes a per cluster shadowing term IN dB, rτ denotes a delay distribution proportionality factor, ξn(p, q) denotes a two-dimensional spatial lognormal process for simulating smooth power variations over antenna arrays.
In wide bandwidth scenarios, the power value is multiplied by
in the frequency domain by taking frequency domain non-stationary characteristics into account, where γm
In S404, for the survived clusters, small-scale parameters such as the powers and the delays of the sub-paths in the clusters at different time instants are required to be updated. For the trajectory segment at the time instant t1, that is, at the subsequent time instant after the clusters are generated, a coordinate of the p-th transmitter antenna ApT is:
where a coordinate {right arrow over (A)}pT(t0) of the p-th transmitter antenna at the initial time instant is calculated by
{right arrow over (C)}m
The distance from ApT to the first-bounce cluster Cm
In S5, the large-scale parameters and the small-scale parameters are updated according to movements of the transceiver and birth-death processes of the clusters; and new channel coefficients are generated.
A space-time-frequency non-stationarity of the model is mainly reflected in two aspects, one is parameters of space-time-frequency variations, and another is the birth-death processes of the clusters in a space-time-frequency domain, the number of clusters at the time instant t is calculated as follows:
where Nqp(t) denotes the number of the clusters, Nsurv(t) denotes the number of survived clusters determined by a survived probability Psurv(Δt, Δr, Δf) of the clusters, Nnew(t) denotes the number of newly generated clusters following the Poisson distribution with a mean value E[Nnew(t)], λG is defined as a birth rate of the clusters, λR is defined as a combination rate (death rate) of the clusters. In order to model a space-time-frequency evolution process of the clusters more accurately, two types of sampling intervals are introduced, one type is a time domain sampling interval Δt, a frequency domain sampling interval Δf and a space domain (array domain) sampling interval Δr, and channel parameters are updated continuously, another type is described by ΔtBD, ΔfBD and ΔrBD that are integer multiples of corresponding Δt, Δf and Δr, and during the birth-death processes and the evolution processes of the clusters occurred at sampling points, survived probabilities of the transmitter side and receiver side clusters along the array axis and time axis are as follows:
denote position differences of the transmitter antenna element and the receiver antenna element on the array axis and the time axis, respectively, DcA and DcS denote scenario-dependent factors on the array axis and the time axis, respectively, a joint survived probability of the transmitter side and receiver side clusters is represented as follows:
P
surv(ΔtBD, δp, δq)=PsurvT(ΔtBD, δp)PsurvR(ΔtBD, δq).
The average number of the newly generated clusters is:
When wide bandwidth scenarios are studied, the birth-death processes of the clusters also exist on a frequency axis, and a survival probability of the clusters on the frequency axis is:
where F(ΔfBD) and Dcf are determined by channel measurements, Dcf denotes a scenario-dependent factor on the frequency axis, in summary, when the birth-death processes of the space-time-frequency domain clusters are taken into account, the survived probability of the clusters is:
P
surv(ΔtBD, ΔrBD, ΔfBD)=PsurvT(ΔtBD, δp)PsurvR(ΔtBD, δq)Psurv(ΔfBD).
The average number of the newly generated clusters is:
In UHST scenarios, by taking account of a waveguide effect and an impact of tube wall roughness on channels in vacuum tube UHST scenarios, the average number of the newly generated clusters is:
where Dqp(t) denotes a linear distance between the transmitter side and the receiver side at the time instant t, D denotes an initial distance between the transmitter side and the receiver side, ρs denotes a scattering coefficient of the tube wall, and ρs
Based on the above method and the geometric relationship between the transmitter, the receiver and the scatterers, the small-scale parameters of different antenna pairs can be obtained, so that all parameter values in the channel matrix can be obtained. The modeling method and corresponding parameters for the model are summarized in the following table.
By adjusting the parameters, the 6GPCM can be simplified into multiple dedicated channel models, as illustrated in Table 2.
Mn(t) = Mn
Mn(t) = Mn
The present disclosure is described in detail in combination with the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the present disclosure, and the specific embodiments and specific operation processes are given, but the protection scope of the present disclosure is not limited to the following embodiments.
By taking the scenario of the ultra-massive MIMO at millimeter band as an example, a channel matrix of a 6GPCM is represented as:
where PL denotes path loss, SH denotes shadowing, BL denotes blockage loss, AL denotes atmospheric gas absorption loss,
where MT (MR) denotes the number of antenna elements in the transmitter (receiver) antenna array, hqp,f
where KR(t) denotes a Rice factor, hqp,f
where {*}T denotes a transposition operation, fc denotes a carrier frequency, Fp(q),f
{right arrow over (d)}qp(t) denotes a vector distance between the transmitter antenna array ApT and the receiver antenna array AqR at the time instant t, c denotes a speed of light, τqp,m
The detailed steps for generating channel coefficients are specifically as follows.
In S1, propagation scenarios and propagation conditions are set; the carrier frequency, the antenna type, the layout of the transceiver and the motion trajectory of the transceiver are determined.
In S2, the path loss, the shadowing, the oxygen absorption and the large scale fading of blockage effect are generated; the method mainly focuses on a modeling for the small-scale fading, and standard channel models for large scale fading are referable to the calculation of this part.
In S3, according to positions and motion conditions of the transceiver, large-scale parameters with spatial consistency of the DS and 4 angle spreads are generated.
Except SH, other corresponding large-scale parameters include DS, ASA, ASD, ESA, ESD, KR and XPR. The generation methods of large-scale parameters are the same. The delay extension DS generation is taken as an example herein and represented as the following formula:
where P=(PT, PR) is composed of transceiver position vectors, PT(t)=(xT(t), yT(t), zT(t)) and PR(t)=(xR(t), yR(t), zR(t)) denote a coordinate vector at the transmitter side and a coordinate vector at the receiver side, respectively, and initial values of which are generated according to simulation environments and requirements; XDS(P) denotes a normal distribution variable generated by the sine wave superposition method and following the spatial consistency with the mean value of 0 and the variance of 1, DSμ,f
In S4, scatterers following an ellipsoid Gaussian scattering distribution are generated, delays, angles and powers of the clusters are calculated according to geographical location information of the transceiver and the scatterers, and channel coefficients are generated.
In S401, positions of the scatterers are obtained by using an ellipsoid Gaussian scattering distribution, the scatterers in the n-th cluster centered on (
In S402, in the multi-bounce channel model, delays of sub-paths in the cluster at the initial time instant are calculated by
where {tilde over (τ)}m
denotes a distance between the first-bounce cluster and the last-bounce cluster, τlink denotes a non-negative variable following an exponential distribution.
In S403, in (ultra-)massive MIMO scenarios, a sub-paths power Pqp,m
where Zn denotes a per cluster shadowing term in dB, rτ denotes a delay distribution proportionality factor, ξn(p, q) denotes a two-dimensional spatial lognormal process for simulating smooth power variations over antenna arrays.
At the mmWave band, in wide bandwidth scenarios, the power value is multiplied by
in the frequency domain by taking frequency domain non-stationary characteristic into account, where γm
In S404, for the survived clusters, small-scale parameters such as the powers and the delays of the sub-paths in the clusters at different time instants are required to be updated. For the trajectory segment at the time instant t1, that is, at the subsequent time instant after the clusters are generated, a coordinate of the p-th transmitter antenna ApT is:
where a coordinate {right arrow over (A)}pT(t0) of the p-th transmitter antenna at the initial time instant is calculated by
can be calculated by
The distance from ApT to the first-bounce cluster Cm
In S5, the large-scale parameters and the small-scale parameters are updated according to the movements of the transceiver and the birth-death processes of the clusters; and new channel coefficients are generated.
A space-time-frequency non-stationarity of the model is mainly reflected in two aspects, one is parameters of space-time-frequency variations, and another is the birth-death processes of the clusters in a space-time-frequency domain, the number of clusters at the time instant t is calculated as follows:
where Nqp(t) denotes the number of the clusters, Nsurv(t) denotes the number of survived clusters, determined by a survived probability Psurv(Δt, Δr, Δf) of the clusters, Nnew(t) denotes the number of newly generated clusters following the Poisson distribution with a mean value E[Nnew(t)], λG is defined as a birth rate of the clusters, λR is defined as a combination rate (death rate) of the clusters. In order to model a space-time-frequency evolution process of the clusters more accurately, two types of sampling intervals are introduced, one type is a time domain sampling interval Δt, a frequency domain sampling interval Δf and a space domain (array domain) sampling interval Δr, and channel parameters are updated continuously, another type is described by ΔtBD, ΔfBD and ΔrBD that are integer multiples of corresponding Δt, Δf and Δr, and during the birth-death processes and the evolution processes of the clusters occurred at sampling points, survived probabilities of the transmitter side and receiver side clusters along the array axis and time axis are as follows:
denote position differences of the transmitter antenna element and the receiver antenna element on the array axis and the time axis, respectively, DcA and DcS denote scenario-dependent factors on the array axis and the time axis, respectively, a joint survived probability of the transmitter side and receiver side clusters is represented as follows:
P
surv(ΔtBD, δp, δq)=PsurvT(ΔtBD, δp)PsurvR(ΔtBD, δq).
The average number of the newly generated clusters is:
When wide bandwidth scenarios are studied, the birth-death processes of the clusters also exist on a frequency axis, and a survived probability of the clusters on the frequency axis is:
where F(ΔfBD) and Dcf are determined by channel measurements, Dcf denotes a scenario-dependent factor on the frequency axis. In summary, when the birth-death processes of the space-time-frequency domain clusters are taken into account, the survived probability of the clusters is:
P
surv(ΔtBD, ΔrBD, ΔfBD)=PsurvT(ΔtBD, δp)PsurvR(ΔtBD, δq)Psurv(ΔfBD).
The average number of the newly generated clusters is:
Based on the above method and the geometric relationship between the transmitter, the receiver and the scatterers, the small-scale parameters of different antenna pairs can be obtained, so that all parameter values in the channel matrix can be obtained.
Number | Date | Country | Kind |
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202210235058.9 | Mar 2022 | CN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/CN2023/082380 | 3/19/2023 | WO |