CN114095318A - Intelligent super-surface-assisted hybrid configuration millimeter wave communication system channel estimation method - Google Patents
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Abstract
The invention discloses an intelligent super-surface assisted channel estimation method for a hybrid configuration millimeter wave communication system. The method comprises the steps of firstly, researching and decomposing channels between a base station and an intelligent reflecting surface based on a singular value decomposition method, and designing a simulation beam forming matrix of the base station end according to the channels. Secondly, by activating the intelligent units on the intelligent reflecting surface in sequence, estimating and accumulating the obtained signals at the base station end, and searching virtual beams based on the accumulated data, the arrival angle (AoA) value of the channel between the user end and the intelligent reflecting surface is measured. The invention only needs to start part of intelligent units on the intelligent reflecting surface, and can fully utilize the existing accumulated information to assist the estimation of the strongest arrival angle, thereby greatly reducing the time overhead and energy consumption of channel estimation. In addition, the channel estimation algorithm fully considers the influence of system hardware errors and prior information matrix errors on subsequent real angle estimation, and the robustness of the algorithm is verified through simulation.
Description
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a multi-user channel estimation method of a novel mixed configuration millimeter wave communication system under the auxiliary condition of an intelligent reflecting surface.
Background
With the shortage of low frequency resources, the fifth generation mobile communication technology (5G) needs to exploit available spectrum resources to a higher frequency band range. Millimeter waves are considered to be one of the most promising technologies in 5G. For high carrier frequency communication systems, high gain beams typically have narrow beamwidths and are easily blocked, which has an impact on the robustness of the received signal. In order to solve the problem, Reconfigurable Intelligent reflecting Surface Reconfiguration (RIS) is proposed to improve the mobile communication performance by dynamically controlling the electromagnetic propagation environment. Under the millimeter wave frequency band communication, when obstacles such as wall surfaces, trees and the like are blocked in the base station end and user end propagation space, the intelligent reflecting surface can be reconstructed through proper configuration, the reflecting factor on the intelligent reflecting surface is designed, and a reflecting link from the user end to the intelligent reflecting surface and then to the base station end can be established, so that the user end and the base station end can be effectively communicated.
However, there is no radio frequency link for signal processing on the reconfigurable intelligent reflecting surface, so that there is difficulty in acquiring channel state information, and therefore, the channel estimation of the intelligent reflecting surface auxiliary communication becomes an important challenge. The reflection factor design of the intelligent reflecting surface is based on acquiring accurate channel state information, but most researches design the reflection factor coefficient based on the known channel state information so as to optimize the communication performance. At present, most of channel estimation researches aiming at the intelligent reflecting surface jointly estimate a cascade channel from a user to the intelligent reflecting surface and then to a base station end. The invention designs the corresponding base station to receive the analog wave beam by utilizing the singular value decomposition information of the base station and the intelligent reflecting surface channel, and obtains the channel state information from a user side to the intelligent reflecting surface. And under the condition of acquiring partial channel information, searching and estimating a corresponding arrival angle through the virtual beam.
Disclosure of Invention
The invention provides a novel multi-user channel estimation method under the auxiliary condition of an intelligent reflecting surface, aiming at a mixed configuration millimeter wave communication system assisted by a reconfigurable intelligent reflecting surface. The method comprises the steps of firstly, researching and decomposing channels between a base station and an intelligent reflecting surface based on a singular value decomposition method, and designing a simulation beam forming matrix of the base station end and unit division of the intelligent reflecting surface according to the channel. Secondly, by activating the intelligent unit groups on the intelligent reflecting surface in sequence, estimating and accumulating the obtained signals at the base station end, and searching virtual beams based on the accumulated data, the arrival angle value of the channel between the user end and the intelligent reflecting surface is measured. The invention only needs to start part of intelligent units on the intelligent reflecting surface, and can fully utilize the existing accumulated information to assist the estimation of the strongest arrival angle, thereby greatly reducing the time overhead and energy consumption of channel estimation. In addition, the channel estimation algorithm fully considers the influence of system hardware errors and prior information matrix errors on subsequent real angle estimation, and the robustness of the algorithm is verified through simulation.
The technical scheme of the invention comprises the following steps:
further, step 1 is specifically as follows:
the scenario assumptions and channel models are described as follows: a base station equipped with M antennas communicates with K single-antenna users with the aid of an intelligent reflector with N passive reflecting elements. The communication channel model under the intelligent reflecting surface comprises three parts: the channel matrix from the base station end of the reflecting chain to the intelligent reflecting surface is expressed as
The reflection channel matrix from the user side to the intelligent reflection surface is expressed as
Through toThe channel matrix from the channel user side to the base station side is represented as
Wherein, it is assumed that a direct channel from a user terminal to a base station terminal in a transmission model is blocked by a barrier; and the base station end and the intelligent reflector antenna array both adopt uniform linear arrays. The rice channel is adopted as a reflection channel model between the user side and the intelligent reflection surface. Wherein
Expressed as a matrix of coefficients of reflective elements, beta, on the intelligent reflecting surfacen∈[0,1]And phin∈[0,2π]Respectively representing the amplitude and phase adjustment coefficients of the nth passive reflection element of the RIS.
Further, step 2 is specifically as follows:
and 2-1, in order to reduce the overhead cost of channel estimation, performing Singular Value Decomposition (SVD) on the channel G and observing the number of singular values of the corresponding channel. Screening out all singular values of which the singular values are larger than a set threshold value, and counting the number of the screened singular values; dividing passive element groups on the intelligent reflecting surface according to the number P of singular values, and dividing the passive element groups on the intelligent reflecting surface by taking P passive elements as one passive element group (the number of the passive elements on the intelligent reflecting surface and the number of observation channels with the singular values larger than a set threshold value is a multiple relation); so as to simultaneously turn on a plurality of passive devices for channel estimation operations; the following situations exist when the passive element group on the intelligent reflecting surface is divided by the number P of singular values:
by observing the number of singular values larger than the threshold, assuming that the number larger than the threshold is 3, 4 or 5, the common multiple of the number of the passive devices on the intelligent reflecting surface larger than the threshold is 3, 4, 5 or 60;
if the situation 2 is met, if the even division cannot be carried out, if every three of 64 devices are divided into one group, 21 groups of devices have 1, and finally, the device does not need to measure 1 any more, so that the subsequent beam search is not influenced;
2-2. when activated simultaneouslyWhen P passive devices are arranged on the intelligent reflecting surface, the passive unit group on the intelligent reflecting surface is connected to the channel of the base station end, and the user end is connected to the base station end
q∈{1,…,Q}，
The channels of the set of table passive elements can be denoted in turn by GqE is shown as a matrix of phase amplitude coefficients of the passive element groups on the intelligent reflecting surface.
Through the pair channel GqSingular value decomposition is carried out to obtain:
wherein G isqSingular value matrix of
The diagonal matrix is a negative real number diagonal matrix which is arranged in a descending order, and is arranged from large to small, and the parameter superscript H in the formula (1) represents a conjugate transpose;
and
is a unitary matrix with characteristics of
2-3, by activating the passive unit groups on the intelligent reflecting surface in sequence, the user side transmits the pilot signal X to be reflected to the base station side through the passive unit groups on the intelligent reflecting surface, and the transmission model is as follows:
wherein,
for pilot sequences, W, sent in T time slots for all clientsRF,qThe analog beam forming matrix at the base station end is synthesized by adopting a phase shifter network.
To maximize the performance of the transmission system, the analog precoding is set to the unitary matrix U obtained by decompositionqConjugate transpose of the first P columns, i.e.
The base station end received signal is represented as follows:
Yq＝WRF,qGqΘqHr,qX+WRF,qZBS
＝ΛqΘqHr,qX+WRF,qZBS (3)
wherein, define
Further, step 3 is specifically as follows:
and (3) obtaining a linear equation by using the transmission model in the step (2), and estimating a channel from the user side to the intelligent reflecting surface by using a least square method:
can estimate
Namely:
wherein,
the representation is a left pseudo-inverse matrix. In channel estimation, the amplitude of all the passive devices of the intelligent reflecting surface is set to be 1, so that theta can be obtainedqIs an identity matrix. By correspondingly activating the intelligent reflection units in turn, channel data accumulation and observation, an estimated channel can be derived, i.e.
Further, step 4 is specifically as follows:
and 3, according to the sparsity characteristic of the millimeter wave communication channel, finding the strongest arrival angle from the user side to the intelligent reflecting surface by only using the partial channel information estimated in the step 3 to search the virtual beam. By searching for partial channels
The sight distance reaching angle value from each user side to the intelligent reflecting surface can be estimated. Designing an arrival angle detection matrix as follows:
including J columns of detected vectors, the ith column of detected vectors, i.e. the
The following were used:
wherein,
is the possible angle of arrival of the intelligent reflecting surface. d represents the distance between adjacent antennas, and the beam search value for the ith virtual direction is:
wherein,
indicating the Rice factor weight coefficient matrix of different user terminals.
The virtual beam search maximum may be expressed as:
and the index corresponding to the maximum search value is the strongest arrival angle value from the user side to the intelligent reflecting surface.
The invention has the following beneficial effects:
the invention only needs to start part of intelligent units on the intelligent reflecting surface, and can fully utilize the existing accumulated information to assist the estimation of the strongest arrival angle, thereby greatly reducing the time overhead and energy consumption of channel estimation. In addition, the channel estimation algorithm fully considers the influence of system hardware errors and prior information matrix errors on subsequent real angle estimation, and the robustness of the algorithm is verified through simulation.
Drawings
FIG. 1 is a communication system assisted by an intelligent reflector;
FIG. 2 is a flow diagram of a reflected channel estimation implementation;
fig. 3 shows a virtual beam search beam pattern from a user side to an intelligent reflecting surface;
fig. 4 shows the influence of different numbers of radio frequency links configured at the base station end on channel estimation;
FIG. 5 shows the variation relationship of Mean Square Error (MSE) from the user to the channel of the intelligent reflector along with the signal-to-noise ratio under different error weights;
FIG. 6 shows that the variation of the line-of-sight angle from the user to the channel of the intelligent reflector along with the signal-to-noise ratio is measured under different error weights;
FIG. 7 shows the variation of the average achievable data transmission rate with the signal-to-noise ratio under different error weights;
Detailed Description
The following describes the specific implementation method of the present invention with reference to the attached drawings.
As shown in fig. 1 and 2, the channel estimation method of the intelligent super-surface assisted hybrid configuration millimeter wave communication system specifically comprises the following implementation steps:
a multi-antenna base station and a single-antenna multi-user millimeter wave communication scene are considered, a direct link between a base station end and a user is assumed to be blocked by a barrier, and a new reflection link is established through a reconfigurable intelligent reflection surface to carry out communication. The propagation environment is dynamically changed between the base station end and the intelligent reflecting surface through the controller. Initialization setting and model building: setting a channel Rice factor theta, the number M of base station end antennas, the number N of passive elements on an intelligent reflecting surface, the number K of single antenna users, the number of channel scattering paths, the setting of signal-to-noise ratio (SNR) and the design of pilot signals. The millimeter wave system assumes that the channel is a rice channel that fades slowly over a coherent time slot, and thus the channel is constant over a time slot. Fig. 1 shows a transmission model under the auxiliary communication of the intelligent reflecting surface.
The channel matrix from the base station end of the reflection chain to the intelligent reflecting surface can be expressed as
The reflection channel matrix from the user side to the intelligent reflection surface is expressed as
The reflection channels from the kth user end to the intelligent reflection surface and then to the base station end are respectively expressed as follows:
wherein, neglecting subscript, θ represents the rice factor, which is the ratio of the power of the main path-of-arrival component LoS to the power of the scattering path component NLoS; gLoS，
Respectively representing the main reaching path from the intelligent reflecting surface to the base station end and from the kth user to the intelligent reflecting surface; gNLoS，
Respectively representing the scattering paths from the intelligent reflecting surface to the base station section and from the kth user to the intelligent reflecting surface; and the base station end and the intelligent reflector antenna array both adopt uniform linear array response. Channel H for all usersr＝[hr,1 … hr,K]Can be expressed as follows:
Hr＝HLVL+HSVS (3)
wherein,
is the rice factor for different users.
2-1, along with the increase of the number of the passive devices, the channel estimation time overhead and the energy consumption overhead of the intelligent reflecting surface are continuously increased. In order to reduce the overhead cost of channel estimation, step 1 is utilized to decompose the channel G by singular value decomposition as follows:
G＝U∑VH (4)
wherein,
is a unitary matrix with a property of UHU＝IM×M，VHV＝IN×NThe parameter superscript "H" in equation (4) represents the conjugate transpose; singular value matrix of G
Is where the diagonal elements are non-negative real numbers and the diagonal elements are ordered singular values of the matrix G. And observing the number of the singular values of the corresponding channel G. The passive units on the intelligent reflecting surface are designed and divided by the number of large singular values (the number of diagonal elements with large values is assumed to be P), so that a plurality of passive devices are simultaneously started to carry out channel estimation operation.
2-2. when the P passive devices on the intelligent reflecting surface are activated simultaneously, the channel from the intelligent unit to the base station end and the channel from the user end to the intelligent unit can be sequentially expressed as
Expressed as the phase amplitude coefficient of the passive elements on the intelligent reflecting surface.
In order to reduce the energy consumption and cost of the system as much as possible and meet the development characteristics of a millimeter wave communication system, the invention designs a mixed analog-digital architecture and estimates the channel from a user side to an intelligent reflection unit on the basis of assuming the state information of the channel between a known intelligent reflection surface and a base station.
For channel GqSingular Value Decomposition (SVD) is performed to obtain:
wherein G isqSingular value matrix of
Is a diagonal matrix of non-negative real numbers in descending order,
and
is a unitary matrix with characteristics of
2-3. by activating the intelligent reflecting unit groups in sequence
The user side transmits a pilot signal X to be reflected to the base station side through a unit on the intelligent reflecting surface, and the transmission model is as follows:
wherein,
pilot sequences sent in T slots for all users. WRF,qAnalog beam forming is carried out at a base station end, and a phase shifter network is adopted for synthesis, so that a mixed analog-digital configuration is formed. ZBSObeying a mean value of 0 and a variance of σ2White additive gaussian noise.
To maximize the performance of the transmission system, the analog precoding is set to the unitary matrix U obtained by decompositionqConjugate transpose of the first P columns, i.e.
The base station end received signal is represented as follows:
Yq＝WRF,qGqΘqHr,qX+WRF,qZBS (7)
＝ΛqΘqHr,qX+WRF,qZBS (8)
wherein, define
and (3) obtaining a linear equation by using the transmission model in the step (2), and estimating a channel from a user side to the intelligent reflecting surface by using a least square method (LS):
can estimate
Namely:
wherein,
the representation is a left pseudo-inverse matrix. The above formula can be written as:
in channel estimation, the amplitude of all the passive devices of the intelligent reflecting surface is set to be 1, so that theta can be obtainedqIs an identity matrix. By activating the respective intelligent reflection units in turn, the channel data are accumulated and observed, an estimated channel can be derived, i.e.
and (3) according to the sparsity characteristic of the millimeter wave communication channel, finding the strongest arrival angle from the user side to the intelligent reflecting surface by only using the partial channel information estimated in the step (3) to search the virtual beam. By searching for partial channels
The sight distance reaching angle value from each user to the intelligent reflecting surface can be estimated. The user side searches virtual beams from 0 to 180 DEG, and the angle searching step length is
And estimating to obtain the strongest arrival angle. Designing an arrival angle detection matrix as
If the search matrix contains J columns of detected vectors, the ith column of detected vectors, i.e. the
The following were used:
wherein,
the possible arrival angle of the intelligent reflecting surface is characterized by
The beam search value for the ith virtual direction is:
the virtual beam search maximum may be expressed as:
wherein, the index corresponding to the maximum search value is the strongest arrival angle value from the user end to the intelligent reflecting surface, that is, the sight distance arrival angle from the user end to the intelligent reflecting surface is
wherein,
the method comprises the steps that a beam forming vector of a base station end is marked with a mark "+" in a parameter to represent conjugation, and the vector is designed to be a unitary matrix U corresponding to the maximum singular value in ordered singular values of a matrix G; the design of theta is based on the strongest arrival angle of the user side and the intelligent reflecting surface and the vector of the unitary matrix V corresponding to the maximum singular value obtained by the decomposition of G singular value, and the vector is expressed as follows:
wherein,
based on the arrival angle of the line of sight between the kth user and the intelligent reflecting surface channel measured by the virtual beam in the step 4; v. of1The wave beam forming vector is expressed from the base station end to the intelligent reflecting surface end of the intelligent reflecting surface; an operation symbol "" in the formula indicates a hadamard product.
Equivalent channel Heq,kIncluding line-of-sight paths and scatter paths, where scatter paths are sources of interference, as follows:
thus, the received signal to interference plus noise ratio (SINR) for user k is:
the data transmission rate of each user at this time can be expressed as:
Rk＝log2(1+SINRk)，k＝1,…,K
the total data transmission rate achievable by the system is:
and 6, considering the errors of subsequent channel information estimation and angle estimation and the influence on the downlink transmission efficiency caused by system hardware errors and prior information matrix errors. Considering the condition that the channel state information of the base station end and the intelligent reflecting surface has errors, namely:
where p is the error weight,
which is a source of channel error, obeys a standard normal gaussian distribution. And 4, under the condition of an error existing in the step 4, the error of the arrival angle measured by searching the virtual beam of the channel between the user side and the intelligent reflecting surface can be obtained. The view distance arrival angle between the user side and the intelligent reflecting surface measured under different error weights in the virtual beam search has influence on the design of downlink data transmission theta. Depending on the design Θ, the impact on the average achievable data transmission rate can be studied.
Example (b):
in simulation, a base station end is provided with uniform linear arrays with 16 half-wavelength antennas at intervals, 8 single-antenna users, and an intelligent reflecting surface is provided with 64 passive reflecting elements. In the example where the pilot channel is transmitted in 8 slots, the SNR is 5dB apart, ranging from 5dB to 20 dB. Other parameters were set as follows: the number of scattering paths between the base station end and the intelligent reflecting surface is 11, and the number of scattering paths between the intelligent reflecting surface and a single user is 5.
Fig. 3 shows a beam pattern for performing virtual beam search on an estimated channel given the known channel state information G. Different colors in the figure represent different users.
Fig. 4 shows that, based on the known channel state information G, when the base station configures different radio frequency links, that is, the unitary matrix is obtained after G singular value decomposition
And observing the number of singular values of the corresponding channel G, and respectively taking the vector in the unitary matrix U corresponding to the larger number of the singular values to design the beam forming of the base station end. In the figure, different radio frequency links are configured at the base station end, and the change relation of Mean Square Error (MSE) from a user to an intelligent reflector channel along with the signal-to-noise ratio is shown.
Fig. 5 shows the performance of testing different error weights for channel estimation of the ue and the intelligent reflective surface under different snr. The black line represents the known channel state information of the base station end and the intelligent reflecting surface, and the red line represents the influence on channel estimation under different error weights.
Fig. 6 shows that, under different error weights, the estimated channel performs virtual beam search to measure the error of the angle value of the line of sight. Even when the error weight is 0.1, the measured angle error is 2.5 ° or less. Fig. 7 shows the variation of the average achievable data transmission rate with SNR for different error weights. Based on the virtual beam searching and fine estimation method of the arrival angle between the user side of the observation data and the intelligent reflecting surface in the step 4, the measured sight distance angle value is used for designing elements on the intelligent reflecting surface, a change diagram of the average achievable data transmission rate under different weights is simulated through downlink data transmission, and the robustness of the algorithm of the invention can be seen from the curve change of the simulation diagram.
Claims (5)
1. The channel estimation method of the intelligent super-surface-assisted hybrid configuration millimeter wave communication system is characterized by comprising the following steps of:
step 1, scene hypothesis and a channel model;
step 2, designing beam forming of the base station end and dividing an intelligent reflecting surface unit group by using a channel singular value decomposition result from the base station end to the intelligent reflecting surface;
step 3, observing and accumulating channel data from the user side to each unit group on the intelligent reflecting surface;
step 4, according to the observation data, virtual beam search and fine estimation of the arrival angle between the user side and the intelligent reflecting surface are executed; and measuring the sight distance reaching angle from the user side to the intelligent reflecting surface.
2. The method for channel estimation of an intelligent super-surface assisted hybrid configuration millimeter wave communication system according to claim 1, wherein the step 1 is as follows:
the scenario assumptions and channel models are described as follows: a base station configured with M antennas communicates with K single-antenna users with the aid of an intelligent reflecting surface with N passive reflecting elements; the communication channel model under the intelligent reflecting surface comprises three parts: the channel matrix from the base station end of the reflecting chain to the intelligent reflecting surface is expressed as
The reflection channel matrix from the user side to the intelligent reflection surface is expressed as
The channel matrix from the direct channel user terminal to the base station terminal is expressed as
Wherein, it is assumed that a direct channel from a user terminal to a base station terminal in a transmission model is blocked by a barrier; the base station end and the intelligent reflector antenna array both adopt uniform linear arrays; a rice channel is adopted as a reflection channel model between the user side and the intelligent reflection surface; wherein
Expressed as a matrix of coefficients of reflective elements, beta, on the intelligent reflecting surfacen∈[0，1]And phin∈[0，2π]Respectively representing the amplitude and phase adjustment coefficients of the nth passive reflection element of the RIS.
3. The method for channel estimation in an intelligent super-surface assisted hybrid configuration millimeter wave communication system according to claim 1, wherein the step 2 is as follows:
2-1, in order to reduce the overhead cost of channel estimation, carrying out Singular Value Decomposition (SVD) on a channel G, and observing the number of singular values of the corresponding channel; screening out all singular values of which the singular values are larger than a set threshold value, and counting the number of the screened singular values; dividing passive unit groups on the intelligent reflecting surface according to the number P of singular values, and dividing the passive unit groups on the intelligent reflecting surface by taking P passive devices as one passive unit group; so as to simultaneously turn on a plurality of passive devices for channel estimation operations;
2-2, when the passive devices on the P intelligent reflection surfaces are activated simultaneously, the channels from the passive unit group to the base station end on the intelligent reflection surface, and the channels from the user end to the passive unit group can be sequentially expressed as,
expressed as a phase amplitude coefficient matrix of the passive unit group on the intelligent reflecting surface;
through the pair channel GqSingular value decomposition is carried out to obtain:
wherein G isqSingular value matrix of
The diagonal matrix is a negative real number diagonal matrix which is arranged in a descending order, and is arranged from large to small, and the parameter superscript H in the formula (1) represents a conjugate transpose;
and
is a unitary matrix with characteristics of
2-3, by activating the passive unit groups on the intelligent reflecting surface in sequence, the user side transmits the pilot signal X to be reflected to the base station side through the passive unit groups on the intelligent reflecting surface, and the transmission model is as follows:
wherein,
for pilot sequences, W, sent in T time slots for all clientsRF，qThe method comprises the steps that an analog beam forming matrix of a base station end is synthesized by adopting a phase shifter network;
obeying a mean value of 0 and a variance of σ2Additive white gaussian noise of (1);
to maximize the performance of the transmission system, the analog precoding is set to the unitary matrix U obtained by decompositionqConjugate transpose of the first P columns, i.e.
The base station end received signal is represented as follows:
Yq＝WRF，qGqΘqHr，qX+WRF，qZBS
＝ΛqΘqHr，qX+WRF，qZBS (3)
wherein, define
4. The method for estimating the reflection channel under the auxiliary communication of the reconfigurable intelligent reflecting surface according to claim 1, wherein the step 3 is as follows:
and (3) obtaining a linear equation by using the transmission model in the step (2), and estimating a channel from the user side to the intelligent reflecting surface by using a least square method:
can estimate
Namely:
wherein,
the representation is a left pseudo-inverse matrix; in channel estimation, the amplitude of all the passive devices of the intelligent reflecting surface is set to be 1, so that theta can be obtainedqIs an identity matrix; by correspondingly activating the intelligent reflection units in turn, channel data accumulation and observation, an estimated channel can be derived, i.e.
5. The method for estimating the reflection channel under the auxiliary communication of the reconfigurable intelligent reflecting surface according to claim 4, wherein the step 4 is as follows:
according to the sparsity characteristic of the millimeter wave communication channel, the strongest arrival angle from the user side to the intelligent reflecting surface is found only by estimating in the step 3Performing virtual beam search on the partial channel information; by searching for partial channels
The sight distance reaching angle value from each user side to the intelligent reflecting surface can be estimated; designing an arrival angle detection matrix as follows:
including J columns of detected vectors, the ith column of detected vectors, i.e. the
The following were used:
wherein,
is the possible angle of arrival of the intelligent reflecting surface; d represents the distance between the transmitting antenna and the receiving antenna, and the beam search value of the ith virtual direction is:
wherein,
representing a Rice factor weight coefficient matrix of different user sides;
the virtual beam search maximum may be expressed as:
and the index corresponding to the maximum search value is the strongest arrival angle value from the user side to the intelligent reflecting surface.
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| CN114553643A (en) * | 2022-04-24 | 2022-05-27 | 杭州电子科技大学 | Millimeter wave intelligent super-surface channel estimation method based on double-time scale cooperative sensing |
| CN114866126A (en) * | 2022-03-25 | 2022-08-05 | 北京邮电大学 | Low-overhead channel estimation method of intelligent reflector assisted millimeter wave system |
| CN114900400A (en) * | 2022-05-24 | 2022-08-12 | 华南理工大学 | Joint sparse channel estimation method based on intelligent reflector assisted Internet of things |
| CN114978821A (en) * | 2022-05-18 | 2022-08-30 | 西安交通大学 | Cooperative channel estimation method for 6G intelligent reflection surface-oriented auxiliary communication system |
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| CN112887002A (en) * | 2021-01-13 | 2021-06-01 | 之江实验室 | Wave beam domain channel angle estimation method for intelligent reflector auxiliary communication |
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| CN114978821A (en) * | 2022-05-18 | 2022-08-30 | 西安交通大学 | Cooperative channel estimation method for 6G intelligent reflection surface-oriented auxiliary communication system |
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