CN115426024B - Phase adjusting method of intelligent reflecting surface capable of spatial multiplexing - Google Patents
Phase adjusting method of intelligent reflecting surface capable of spatial multiplexing Download PDFInfo
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Abstract
The invention discloses a phase adjusting method of a spatial multiplexing intelligent reflecting surface, which is applied to the intelligent reflecting surface, wherein the intelligent reflecting surface comprises a reflecting front surface positioned in a central area and a plurality of angle sensing units distributed around the reflecting front surface, and the method comprises the following steps: acquiring a receiving signal and a local oscillator signal of each angle sensing unit; respectively carrying out frequency mixing on each received signal according to the local oscillator signal to obtain a frequency mixing signal of each angle sensing unit; determining an incoming wave direction angle according to each mixing signal; and acquiring a target codebook, and determining phase adjustment data corresponding to the reflection array surface according to the incoming wave direction angle and the target codebook. The invention mixes the received signals by the local oscillation signals with different frequencies to realize the phase adjustment of the reflection array surface, realizes the spatial multiplexing and is suitable for multi-user terminal communication. The problem of the present intelligent plane of reflection receiving and dispatching share a radio frequency point, the up-and downlink carries out communication with different time slots, does not consider spatial multiplexing, leads to the communication cost higher is solved.
Description
Technical Field
The invention relates to the technical field of electronic information, in particular to a phase adjusting method of an intelligent reflecting surface capable of spatial multiplexing.
Background
As one of the most promising leading technologies in the next generation mobile communication system, the Intelligent Reflective Surface (IRS) is widely and deeply studied by the industry and the academic community. The method is proved to be capable of realizing the functions of beam forming, vortex space multiplexing, space coding and the like, thereby realizing the improvement of the system communication capacity and even bringing about the revolution of a hardware system architecture. At present, the intelligent reflecting surface has a bright application prospect in the aspects of indoor and outdoor enhanced coverage, auxiliary multi-user communication and the like, particularly aiming at the problems of high millimeter wave signal attenuation speed and difficulty in permeating a complex environment, the IRS auxiliary communication is a very effective solution, and the scheme can effectively realize the range extension and fixed-point coverage of signals by re-regulating and controlling the diffusion wavefront. Compared to conventional communication systems and architectures, the introduction of IRS entails additional channel estimation and overhead. In the early period of technical research, the related research and papers regarded the IRS as a device that can estimate the channel, but this brings about a problem that the IRS will become an active device, thereby losing the advantage of low cost. In recent years, more and more research works are being conducted to perform channel estimation by using a semi-passive scheme in combination with angle information of a base station and a user. The scheme greatly reduces the hardware implementation cost and the channel estimation overhead. However, this scheme needs to pay attention to the channel reciprocity of the uplink and downlink, and therefore, it is only suitable for transmitting and receiving a common radio frequency point, and the uplink and downlink use different time slots for communication (TDD scheme), resulting in higher communication cost.
Thus, there is a need for improvement and development of the prior art.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a phase adjustment method for a spatially reusable intelligent reflecting surface, aiming at solving the problem that the existing intelligent reflecting surface shares one radio frequency point for transmitting and receiving, and different time slots are used for the uplink and downlink to communicate, and spatial multiplexing is not considered, resulting in higher communication cost.
The technical scheme adopted by the invention for solving the problems is as follows:
in a first aspect, an embodiment of the present invention provides a phase adjustment method for a spatially-reusable intelligent reflective surface, where the method is applied to an intelligent reflective surface, where the intelligent reflective surface includes a reflective front located in a central area and a plurality of angle sensing units distributed around the reflective front, and the method includes:
acquiring a received signal and a local oscillator signal respectively corresponding to each angle sensing unit, wherein the received signal of each angle sensing unit is from a user terminal, and different user terminals respectively correspond to different local oscillator frequencies;
respectively carrying out frequency mixing on each received signal according to the local oscillator signal to obtain frequency mixing signals respectively corresponding to the angle sensing units;
determining an incoming wave direction angle according to each mixing signal;
and acquiring a target codebook, and determining phase adjustment data corresponding to the reflection wavefront according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection wavefront respectively.
In a second aspect, an embodiment of the present invention further provides a base station, where the base station is in communication with an intelligent reflective surface, the intelligent reflective surface includes a reflective front located in a central area and a plurality of angle sensing units distributed around the reflective front, and the base station includes:
an obtaining module, configured to obtain a received signal and a local oscillator signal corresponding to each of the angle sensing units, where the received signal of each of the angle sensing units is from a user terminal, and different user terminals correspond to different local oscillator frequencies respectively;
the frequency mixing module is used for respectively carrying out frequency mixing on each received signal according to the local oscillator signals to obtain frequency mixing signals respectively corresponding to the angle sensing units;
the determining module is used for determining the incoming wave direction angle according to each mixing signal;
and the adjusting module is used for acquiring a target codebook and determining phase adjusting data corresponding to the reflection front surface according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection front surface respectively.
In a third aspect, an embodiment of the present invention further provides an intelligent reflective surface capable of spatial multiplexing, where the intelligent reflective surface includes a reflective front located in a central area, a plurality of angle sensing units distributed around the reflective front, and a control module, where the control module is respectively connected to the reflective front and each of the angle sensing units;
each angle sensing unit is used for acquiring a signal sent by a user terminal, obtaining a received signal and sending the received signal to the base station;
the reflection array surface is used for acquiring phase adjustment data generated by the base station based on the received signals respectively corresponding to the angle sensing units.
In a fourth aspect, an embodiment of the present invention further provides a mobile communication system, where the system includes a user terminal, the base station as described above, and the intelligent reflective surface capable of spatial multiplexing as described above.
In a fifth aspect, the present invention further provides a computer-readable storage medium, on which a plurality of instructions are stored, wherein the instructions are adapted to be loaded and executed by a processor to implement any of the steps of the phase adjustment method for a spatial-multiplexing intelligent reflective surface described above.
The invention has the beneficial effects that: the embodiment of the invention realizes the phase adjustment of the reflection array surface by mixing the received signals by adopting the local oscillator signals with different frequencies, realizes the spatial multiplexing and is suitable for the communication scene of a multi-user terminal. The problem of current intelligent plane of reflection receiving and dispatching share a radio frequency point, the uplink, downlink use different time slots to communicate, do not consider spatial multiplexing, lead to the communication cost higher is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and it is also possible for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a phase adjustment method for a spatial multiplexing intelligent reflective surface according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a target usage scenario provided by an embodiment of the present invention.
Fig. 3 is a schematic diagram of a system architecture according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of a process for determining an IRS bias voltage distribution according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of spatial pre-partitioning according to an embodiment of the present invention.
Fig. 6 is a schematic flowchart of a normalization algorithm for a discrete-phase reflection front according to an embodiment of the present invention.
Fig. 7 is a schematic functional block diagram of a base station according to an embodiment of the present invention.
Fig. 8 is a functional block diagram of a terminal according to an embodiment of the present invention.
Detailed Description
The invention discloses a phase adjusting method of a spatial multiplexing intelligent reflecting surface, and in order to make the purpose, technical scheme and effect of the invention clearer and clearer, the invention is further described in detail by referring to the attached drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In view of the above-mentioned drawbacks of the prior art, the present invention provides a phase adjustment method for a spatially-reusable intelligent reflective surface, the method being applied to an intelligent reflective surface, the intelligent reflective surface including a reflective front located in a central area and a plurality of angle sensing units distributed around the reflective front, the method including: acquiring a received signal and a local oscillator signal respectively corresponding to each angle sensing unit, wherein the received signal of each angle sensing unit is from a user terminal, and different user terminals respectively correspond to different local oscillator frequencies; respectively carrying out frequency mixing on each received signal according to the local oscillator signal to obtain frequency mixing signals respectively corresponding to the angle sensing units; determining an incoming wave direction angle according to each mixing signal; and acquiring a target codebook, and determining phase adjustment data corresponding to the reflection wavefront according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection wavefront respectively. The invention realizes the phase adjustment of the reflection array surface by mixing the received signals by adopting the local oscillator signals with different frequencies, realizes the spatial multiplexing and is suitable for the communication scene of a multi-user terminal. The problem of current intelligent plane of reflection receiving and dispatching share a radio frequency point, the uplink, downlink use different time slots to communicate, do not consider spatial multiplexing, lead to the communication cost higher is solved.
As shown in fig. 1, the method is applied to an intelligent reflective surface, the intelligent reflective surface comprises a reflective front located in a central area and a plurality of angle sensing units distributed around the reflective front, and the method comprises:
step S100, obtaining a received signal and a local oscillator signal corresponding to each of the angle sensing units, where the received signal of each of the angle sensing units is from a user terminal, and different user terminals correspond to local oscillator signals with different frequencies, respectively.
Specifically, as shown in fig. 3, the intelligent reflective surface in this embodiment is mainly composed of two parts, the first part is a dual-polarized large-scale reflective surface disposed in the central area, which is a completely passive device (except for the control circuit and the diode); the second part is an angle sensing unit arranged around. The angle sensing unit mainly comprises a simple radio frequency link (comprising a local oscillator, a mixer, a filter and a signal processing unit) and a 2 x 2 small array plane consisting of dual-polarized antennas. In practical applications, the user terminal sends a signal, and the angle sensing unit receives the signal. The angle sensing unit can generate different broadband local oscillation frequencies, so that the incident incoming wave angle can be judged by changing the local oscillation frequencies.
In an implementation manner, because the present invention is an incoming wave angle-based integrated sensing scheme, the angle sensing unit may be a module that provides angle information at will, for example, the angle sensing unit may be a directional radio frequency backtracking module or a UWB positioning module.
As shown in fig. 1, the method further comprises:
and step S200, respectively mixing the received signals according to the local oscillator signals to obtain mixed signals respectively corresponding to the angle sensing units.
In short, the angle sensing unit in this embodiment can generate different wideband local oscillator frequencies, so that the incident incoming wave angle can be determined by changing the local oscillator frequencies. Specifically, the local oscillator signal is mixed with the received signal of each unit, so as to obtain a mixed signal of each unit. It should be noted that the local oscillation frequency/local oscillation signal may be formed by a wideband local oscillation tunable filter, and each user terminal occupies different frequency pilot resources, so that the method is suitable for the communication situation of the multi-user situation. In the prior art, the application of the intelligent reflecting surface is based on the channel reciprocity of an uplink channel and a downlink channel, and the spatial multiplexing is not considered, so that the intelligent reflecting surface is only suitable for a TDD system. In this embodiment, the local oscillation frequency of the angle sensing unit is used to realize the positioning capability of the system for different frequencies, and the FDD architecture can be supported, so that the problem that the intelligent reflecting surface in the prior art is only suitable for the TDD system and does not support the FDD architecture is solved.
In an implementation manner, the step S200 specifically includes:
step S201, respectively mixing the received signals according to the local oscillator signals to obtain initial mixing signals respectively corresponding to the angle sensing units;
step S202, filtering each initial mixing signal to obtain the mixing signal corresponding to each angle sensing unit.
Specifically, in this embodiment, after the local oscillator signals are used to mix the received signals of each unit, the signals obtained after mixing need to be input into a low-frequency filter, so as to retain the low-frequency component in the signals obtained after mixing, and obtain the final mixed signals.
For example, the UE transmits an angular frequency of
Of the signal of (1). The angle sensing unit receives the signal. As shown in fig. 4, the local oscillator signal is mixed with the received signal of each angle sensing unit to obtain a new intermediate frequency signal (i.e., an initial mixed signal). Wherein the angular frequency of the local oscillator signal is 2
. Assuming that the angle sensing units are 2 x 2 arrays, the phase difference of the incoming and outgoing signals in the x-direction and the phase difference of the incoming and outgoing signals in the y-direction can be judged. Specifically, the intermediate frequency signal expression is:
wherein, the followingThe corner mark IF represents Intermediate Frequency (Intermediate Frequency), RF represents Radio Frequency (Radio Frequency), LO represents Local Oscillator (Local Oscillator), VRF, VLO, VIF are signal amplitudes of corresponding signals,
representing the phases of the two signals in the x-direction,
representing the two-way signal phase in the y-direction. It can be seen that the intermediate frequency signal has two components in the frequency spectrum,
and
. Therefore, the low-frequency component in the mixed signal can be retained by the low-frequency filter, and the final mixed signal is obtained.
As shown in fig. 1, the method further comprises:
step S300, determining the incoming wave direction angle according to each mixing signal.
Specifically, as shown in fig. 3, each angle sensing unit is composed of a plurality of units arranged in an array, and each angle sensing unit can judge the phase difference of the incoming and outgoing signals in the x-direction and the phase difference of the incoming and outgoing signals in the y-direction, so that the incoming wave direction angle of the incoming wave of the intelligent reflection surface can be comprehensively determined according to the mixing signals of the angle sensing units.
In an implementation manner, the step S300 specifically includes:
step S301, determining initial incoming wave direction angles corresponding to the angle sensing units according to the mixing signals corresponding to the angle sensing units respectively;
step S302, determining the incoming wave direction angle according to each initial incoming wave direction angle.
Specifically, for each angle sensing unit, the angle sensing unit may calculate an initial incoming wave direction angle according to its own mixing signal. In order to improve the accuracy and reliability of the incoming wave direction angle, the present embodiment determines the final incoming wave direction angle (i.e. AOA) by using the initial incoming wave direction angles respectively calculated by the plurality of angle sensing units.
In one implementation, the step S301 specifically includes:
step S3011, determining an x-direction phase difference and a y-direction phase difference corresponding to each angle sensing unit according to each path of signal corresponding to each angle sensing unit;
step S3012, determining an x-direction incoming wave angle corresponding to the angle sensing unit according to the x-direction phase difference, and determining a y-direction incoming wave angle corresponding to the angle sensing unit according to the y-direction phase difference;
step S3013, determining the initial incoming wave direction angle corresponding to the angle sensing unit according to the x-direction incoming wave angle and the y-direction incoming wave angle.
Specifically, the initial incoming wave direction angle of each angle sensing unit includes an x-direction incoming wave angle and a y-direction incoming wave angle. For each angle sensing unit, the angle sensing unit comprises a plurality of receiving units which are arranged in an array, and the frequency mixing signals corresponding to the angle sensing unit comprise a plurality of paths of signals which are in one-to-one correspondence with the receiving units. Because the angle sensing unit is in an array form, the phase difference of the incoming and outgoing signals in the x direction and the phase difference of the incoming and outgoing signals in the y direction can be judged through multiple paths of signals, and the incoming wave angle in the x direction and the incoming wave angle in the y direction corresponding to the angle sensing unit are further obtained. It should be noted that, since the overall system supports dual polarization multiplexing, the embodiment may not only calculate the arrival angle in the x direction and the arrival angle in the y direction, but also calculate different arrival angles of waves with different polarizations.
For example, for each angle sensor unit, knowing the size of the array antenna of the angle sensor unit, assuming that the angle sensor unit is a 2 x 2 array, two signals can be obtained from the x-direction
. While
Wherein, in the process,
,
、
respectively permittivity and permeability in the subspaces. Therefore, according to the formula, the angle of the incoming wave in the x-direction can be calculated
And angle of incoming wave in y-direction
. By passing
I.e. the incoming wave direction angle AoA of the angle sensing unit.
In an implementation manner, the step S302 specifically includes:
step S3021, determining a target x-direction incoming wave angle according to an average value of the x-direction incoming wave angles in each initial incoming wave direction angle;
step S3022, determining a target y-direction incoming wave angle according to an average value of the y-direction incoming wave angles in each initial incoming wave direction angle;
step S3023, determining the incoming wave direction angle according to the target x-direction incoming wave angle and the target y-direction incoming wave angle.
Briefly, the incoming wave direction angle of the intelligent reflecting surface
The final value of (2) is obtained from the average value of each angle sensing unit, thereby ensuring that the data is relatively accurate.
As shown in fig. 1, the method further comprises:
step S400, acquiring a target codebook, and determining phase adjustment data corresponding to the reflection front surface according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection front surface.
Specifically, the present embodiment designs a target codebook of the intelligent reflection surface in advance, where phase responses of different units divided according to the pointing space of the reflection surface are stored in the target codebook. Therefore, the phase adjustment data corresponding to the incoming wave direction angle can be quickly matched from the target codebook through the incoming wave direction angle, and the phase adjustment is carried out on the reflection wavefront through the phase adjustment data, so that the reflected wave of the incoming wave points to a specific angle.
In one implementation, the generating of the target codebook includes:
step S401, pre-dividing the reflection array surface to obtain a plurality of units which are correspondingly arranged into an array by the reflection array surface;
s402, acquiring preset far-field beam information, determining continuously-changed near-field amplitude and phase distribution according to the far-field beam information, and normalizing the near-field amplitude and phase distribution to obtain discretely-changed target near-field phase distribution;
step S403, determining a first codebook corresponding to the row array and a second codebook corresponding to the column array according to the target near-field phase distribution, where the first codebook is used to reflect the post-reflection x-direction arrival angles of the incoming waves corresponding to the units in different rows in the row array, and the second codebook is used to reflect the post-reflection y-direction arrival angles of the incoming waves corresponding to the units in different rows in the column array;
step S404, determining the target codebook according to the first codebook and the second codebook.
In short, the target codebook in the embodiment mainly includes two codebooks, i.e., the first codebook and the second codebook. To generate the target codebook, the reflection front is first pre-divided into a plurality of cells arranged in an array. And then acquiring pre-designed far-field beam information, and determining the continuously-changed near-field phase distribution in an ideal state through the far-field beam information. However, in the design of the intelligent reflecting surface, the response of different units to the incident wave is a discrete state rather than a continuous state, so that the response needs to be converted into a discretely-changed target near-field phase distribution through a preset normalization algorithm. Determining arrival angles in the x direction after the incoming wave reflected waves corresponding to units in different rows in the row array respectively according to the target near-field phase distribution, and storing the arrival angles in the x direction as a first codebook; and determining arrival angles in the y direction after the incoming wave reflected waves corresponding to the units in different columns in the column array according to the target near field phase distribution, and storing the arrival angles in the y direction as a second codebook.
In one implementation, the pre-dividing process is implemented based on the aperture area and the beam width of the reflection wavefront.
Specifically, the embodiment pre-divides the pointing space with adjustable reflection wavefront according to the placement of the wavefront. Usually, the controllable space of a plane array surface does not exceed a hemispherical surface, namely, the space with the normal direction as a collimation axis and the included angle within 90 degrees. According to the antenna theory, the aperture of the array with the Lx is approximate to a sinc function in the corresponding far-field beam function. The appropriate values of Nx and Ny are therefore related to the aperture area of the wavefront. The larger the aperture, the narrower the generated beam, and the denser the divided space becomes, which is more appropriate. Conversely, the smaller the aperture of the front surface, the wider the beam, and the more sparse the divided space is, the more appropriate. In one implementation, as shown in fig. 5, the pre-partition criteria are: when the wavefront is an ideal constant-amplitude cophase (mirror surface), the beam shape and the lobe width are determined by taking-6 dB as a boundary according to the theoretically generated beam, the angle corresponding to the beam width of-6 dB is the width of each space, and finally the space is divided into small squares of Nx Ny dimensions.
In an implementation manner, the generating process of the first codebook specifically includes: determining a plurality of row vectors according to the target near-field phase distribution, wherein different row vectors respectively correspond to different x-direction assignment weights, and the x-direction assignment weights are used for reflecting the x-direction arrival angle after the incoming wave reflection; and determining the first codebook according to each row vector. The generation process of the second codebook specifically comprises the following steps: determining a plurality of column vectors according to the target near-field phase distribution, wherein different column vectors respectively correspond to different y-direction assignment weights, and the y-direction assignment weights are used for reflecting the y-direction arrival angle after the incoming wave is reflected; and determining the second codebook according to each column vector.
In brief, the first codebook is formed by taking line vectors as a group, each line vector stores weight coefficients assigned to the x-direction of the IRS array, each line vector coefficient is different, and the IRS has different assignment to incoming waves in the x-direction. The second codebook is "grouped" in column vectors, each of which stores weight coefficients assigned to the y-direction of the IRS array. The vector coefficients of each column are different, and the shape of the IRS to the incoming wave in the y-direction is different. Two sets of codebooks, one set of codebooks is responsible for dividing the space into different areas from the x-direction, and the assigned weight of each row of vectors points to a specific area after corresponding to the reflected wave of the incoming wave
，
Nx is the number of lines in the codebook, i.e. in space
The number of angles that can be achieved; the other set is responsible for dividing the space into different areas from the y-direction, and the assigned weight of each column of vectors is corresponding to the specific direction of the incoming wave after the wave is reflected
Ny is the number of columns in the codebook, i.e. in space
The number of angles that can be reached.
In one implementation, the step S402 includes:
s4021, determining far field amplitude and phase distribution according to the far field beam information, and performing fast Fourier inverse transformation on the far field amplitude and phase distribution to obtain near field amplitude and phase distribution;
s4022, replacing the amplitude distribution in the near-field amplitude-phase distribution with Gaussian distribution to obtain updated near-field amplitude-phase distribution;
s4023, performing fast Fourier transform according to the updated near-field amplitude-phase distribution to obtain updated far-field amplitude-phase distribution;
step S4024, judging whether the updated near-field amplitude-phase distribution and the updated far-field amplitude-phase distribution both meet a preset target, if not, taking the updated far-field amplitude-phase distribution as the far-field amplitude-phase distribution, continuing to perform the step of performing inverse fast Fourier transform on the far-field amplitude-phase distribution to obtain the near-field amplitude-phase distribution until the updated near-field amplitude-phase distribution and the updated far-field amplitude-phase distribution both meet the preset target, and determining the target near-field phase distribution according to the finally obtained phase distribution in the updated near-field amplitude-phase distribution.
Fig. 6 is a specific flow chart of the normalization algorithm provided in the present embodiment. Specifically, the weight distribution of each angle of the adjustable pointing space of the reflection array surface under the condition of the row array is calculated through a normalization algorithm to form a first codebook. And calculating the weight distribution of the adjustable pointing space of the reflection array surface pointing to each angle under the condition of the array through a normalization algorithm to form a second codebook. It should be noted that in the design and preparation of a true intelligent reflection front, the phase response that each unit can achieve is discrete, typically a front composed of units with 2-bit, i.e., 4 phase responses [0 °,90 °,180 °,270 ° ]. In one implementation, the goal of the normalization algorithm in this embodiment is to take the ideal continuously varying phase profile to the near phase 4 state. It should be noted that the result of the iFFT calculation in fig. 6 is a complex "field" (matrix) that contains the desired magnitude/phase information. However, since the amplitude is determined by the incident wave, the present embodiment assumes a gaussian wave, and the reflection unit does not cause loss and affect the amplitude, so the calculated amplitude distribution is replaced by a gaussian distribution.
In one implementation, the determining the phase adjustment data corresponding to the reflection front according to the incoming wave direction angle and the target codebook includes:
step S405, determining a target row vector according to the target x-direction incoming wave angle and the first codebook;
step S406, determining a target column vector according to the target y-direction incoming wave angle and the second codebook;
step S407, determining the distribution of the weights of the array surfaces corresponding to the reflection array surfaces according to the assignment weights respectively corresponding to the target row vectors and the target column vectors;
step S408, determining the bias distribution data according to the wavefront weight distribution.
Specifically, when determining the incoming wave direction angle (i.e., incident angle)
Later, according to the incoming wave angle of the x-direction in the incoming wave direction angles
Matching a target row vector from the first codebook according to the incoming wave angle of the y-direction in the incoming wave direction angles
And matching a target column vector from the second codebook. And determining the weight distribution of the array surface according to the assignment weights respectively corresponding to the target row vector and the target column vector. And finally, controlling bias distribution of the intelligent reflection array surface according to the weight distribution of the array surface.
In one implementation, matrix multiplication is performed according to the target row vector and the target column vector to obtain the distribution of the wavefront weights.
For example, assuming that the target row vector is Wi and the target column vector is Wj, the final weight bias matrix is obtained by matrix multiplication
。
The invention has the advantages that:
1. the dual-polarization design and application of hardware in the whole framework can support a space polarization multiplexing system. Specifically, in the uplink and downlink frequency division multiplexing (FDD) architecture of the present invention, aoA is not obtained by time sequence training, and therefore, reciprocity between uplink and downlink is not required, so that the integrated architecture of the present invention supports FDD system.
2. The target codebook is generated based on the space pre-division of the discrete phase function, so that the quick response of the codebook and the quick adjustment of the bias distribution of the array surface can be realized.
3. The invention realizes the angle information extraction of the user by utilizing a plurality of self-adaptive direction backtracking array units (angle sensing units), thereby effectively reducing the channel evaluation overhead.
4. The invention realizes the positioning capability of the system to different frequencies by utilizing the local oscillation frequency of the direction backtracking array, thereby supporting the FDD architecture.
5. The invention realizes the multiplexing capability of the IRS auxiliary communication system on the space polarization by utilizing the dual-polarized radio frequency unit and the dual-polarized reflection array surface, thereby improving the communication capacity of the whole system.
Exemplary device
Based on the foregoing embodiments, the present invention further provides a base station, where the base station is in communication with an intelligent reflection surface, the intelligent reflection surface includes a reflection front located in a central area and a plurality of angle sensing units distributed around the reflection front, as shown in fig. 7, and the base station includes:
an obtaining module 01, configured to obtain a received signal and a local oscillator signal that correspond to each of the angle sensing units, where the received signal of each of the angle sensing units comes from a user terminal, and different user terminals correspond to different local oscillator frequencies, respectively;
the frequency mixing module 02 is configured to perform frequency mixing on each received signal according to the local oscillator signal to obtain frequency mixing signals corresponding to each angle sensing unit;
a determining module 03, configured to determine an incoming wave direction angle according to each of the mixing signals;
and an adjusting module 04, configured to acquire a target codebook, and determine phase adjustment data corresponding to the reflection front according to the incoming wave direction angle and the target codebook, where the target codebook is used to reflect phase responses corresponding to different units on the reflection front.
In short, the calculation part in the embodiment is processed by the base station, and the additional processing load of the intelligent reflecting surface is not increased, so that the preparation and implementation cost of the intelligent reflecting surface can be effectively reduced. The base station and the intelligent reflecting surface are arranged in advance, so that the communication environment can be calibrated into the system, the channel and connection conditions are stable, and frequent solution is not needed.
Based on the above embodiment, the present invention further provides an intelligent reflective surface capable of spatial multiplexing, which is characterized in that the intelligent reflective surface includes a reflective front surface located in a central region, a plurality of angle sensing units distributed around the reflective front surface, and a regulation and control module, wherein the regulation and control module is respectively connected to the reflective front surface and each of the angle sensing units;
each angle sensing unit is used for acquiring a signal sent by a user terminal, obtaining a received signal and sending the received signal to the base station;
the reflection array surface is used for acquiring phase adjustment data generated by the base station based on the received signals respectively corresponding to the angle sensing units.
Based on the foregoing embodiments, the present invention further provides a mobile communication system, which is characterized in that the system includes a user terminal, the base station as described above, and the intelligent reflective surface capable of spatial multiplexing as described above.
Specifically, as shown in fig. 2, a basic usage scenario of the present invention is coverage enhancement of indoor millimeter wave signals. And signal improvement on indoor complex scenes is achieved by utilizing an IRS auxiliary communication technology. The system comprises a base station (indoor small base station), a user, an intelligent reflecting surface and a controller. The bias distribution of the intelligent reflecting surface is calculated by the base station and is realized by the control machine. The method can effectively reduce the calculation requirement of the intelligent reflecting surface end, thereby reducing the realization cost of the intelligent reflecting surface.
In one implementation, the target usage scenario of the present invention is millimeter wave communication, and due to the characteristics of millimeter waves, LOS channel communication is performed between devices (UE, pRRU, IRS), so that the angle information represents the required location information, and thus the input of beamforming is given. In addition, millimeter wave frequency is high, wavelength is short, wave front diffusion is fast, and therefore, the incident waves sensed by all the devices are assumed to be plane waves.
Based on the above embodiments, the present invention further provides a terminal, and a schematic block diagram thereof may be as shown in fig. 8. The terminal comprises a processor, a memory, a network interface and a display screen which are connected through a system bus. Wherein the processor of the terminal is configured to provide computing and control capabilities. The memory of the terminal comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the terminal is used for connecting and communicating with an external terminal through a network. The computer program is executed by a processor to implement a phase adjustment method for a spatially-reusable intelligent reflecting surface. The display screen of the terminal can be a liquid crystal display screen or an electronic ink display screen.
It will be understood by those skilled in the art that the block diagram of fig. 8 is a block diagram of only a portion of the structure associated with the inventive arrangements and is not intended to limit the terminals to which the inventive arrangements may be applied, and that a particular terminal may include more or less components than those shown, or may have some components combined, or may have a different arrangement of components.
In one implementation, one or more programs are stored in a memory of the terminal and configured to be executed by one or more processors include instructions for performing a method of phase adjustment of a spatially-reusable intelligent reflecting surface.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, databases, or other media used in embodiments provided herein may include non-volatile and/or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), rambus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
In summary, the present invention discloses a phase adjustment method for a spatially-reusable intelligent reflective surface, which is applied to an intelligent reflective surface, where the intelligent reflective surface includes a reflective front located in a central area and a plurality of angle sensing units distributed around the reflective front, and the method includes: acquiring a received signal and a local oscillator signal corresponding to each angle sensing unit, wherein the received signal of each angle sensing unit comes from a user terminal, and different user terminals correspond to different local oscillator frequencies respectively; respectively carrying out frequency mixing on each received signal according to the local oscillator signals to obtain frequency mixing signals respectively corresponding to the angle sensing units; determining an incoming wave direction angle according to each mixing signal; and acquiring a target codebook, and determining phase adjustment data corresponding to the reflection front surface according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection front surface. The invention realizes the phase adjustment of the reflection array surface by mixing the received signals by adopting the local oscillator signals with different frequencies, realizes the spatial multiplexing and is suitable for the communication scene of a multi-user terminal. The problem of current intelligent plane of reflection receiving and dispatching share a radio frequency point, the uplink, downlink use different time slots to communicate, do not consider spatial multiplexing, lead to the communication cost higher is solved.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (14)
1. A method for adjusting phase of a spatially-multiplexed intelligent reflective surface, the method being applied to an intelligent reflective surface, the intelligent reflective surface including a reflective front located in a central region and a plurality of angle sensing elements distributed around the reflective front, the method comprising:
acquiring a received signal and a local oscillator signal respectively corresponding to each angle sensing unit, wherein the received signal of each angle sensing unit is from a user terminal, and different user terminals respectively correspond to different local oscillator frequencies;
respectively carrying out frequency mixing on each received signal according to the local oscillator signal to obtain frequency mixing signals respectively corresponding to the angle sensing units;
determining an incoming wave direction angle according to each mixing signal;
and acquiring a target codebook, and determining phase adjustment data corresponding to the reflection wavefront according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection wavefront respectively.
2. The method according to claim 1, wherein the mixing the received signals according to the local oscillator signals to obtain mixed signals corresponding to the angle sensing units respectively comprises:
respectively carrying out frequency mixing on each received signal according to the local oscillator signal to obtain initial frequency mixing signals respectively corresponding to the angle sensing units;
and filtering each initial mixing signal to obtain the mixing signal corresponding to each angle sensing unit.
3. The method of claim 1, wherein determining the incoming wave direction angle according to each mixing signal comprises:
determining initial incoming wave direction angles corresponding to the angle sensing units respectively according to the mixing signals corresponding to the angle sensing units respectively;
and determining the incoming wave direction angle according to each initial incoming wave direction angle.
4. The method of claim 3, wherein each of the angle sensors includes a plurality of receivers arranged in an array, the mixed frequency signal corresponding to each of the angle sensors includes a plurality of signals, each of the signals corresponds to one of the receivers, and the determining the initial incoming wave direction angle corresponding to each of the angle sensors according to the mixed frequency signal corresponding to each of the angle sensors includes:
determining the phase difference in the x direction and the phase difference in the y direction corresponding to each angle sensing unit according to each path of signal corresponding to each angle sensing unit;
determining an x-direction incoming wave angle corresponding to the angle sensing unit according to the x-direction phase difference, and determining a y-direction incoming wave angle corresponding to the angle sensing unit according to the y-direction phase difference;
and determining the initial incoming wave direction angle corresponding to the angle sensing unit according to the x-direction incoming wave angle and the y-direction incoming wave angle.
5. The method of claim 4, wherein the determining the incoming wave direction angles according to the initial incoming wave direction angles comprises:
determining a target incoming wave angle in the x direction according to the average value of the incoming wave angles in the x direction in each initial incoming wave direction angle;
determining a target y-direction incoming wave angle according to the average value of the y-direction incoming wave angles in each initial incoming wave direction angle;
and determining the incoming wave direction angle according to the target x-direction incoming wave angle and the target y-direction incoming wave angle.
6. The method of claim 5, wherein the generating of the target codebook comprises:
pre-dividing the pointing space of the reflection array surface to obtain a plurality of units which are correspondingly arranged into an array by the reflection array surface;
acquiring preset far-field beam information, determining continuously-changed near-field amplitude-phase distribution according to the far-field beam information, and performing normalization processing on the near-field amplitude-phase distribution to obtain discretely-changed target near-field phase distribution;
determining a first codebook corresponding to the row array and a second codebook corresponding to the column array according to the target near-field phase distribution, wherein the first codebook is used for reflecting the arrival angles in the x direction after the incoming wave reflected wave respectively corresponding to the units in different rows in the row array, and the second codebook is used for reflecting the arrival angles in the y direction after the incoming wave reflected wave respectively corresponding to the units in different columns in the column array;
and determining the target codebook according to the first codebook and the second codebook.
7. The method for adjusting the phase of a spatially-reusable intelligent reflecting surface according to claim 6, wherein the determining a continuously-changing near-field amplitude-phase distribution according to the far-field beam information, and normalizing the near-field amplitude-phase distribution to obtain a discretely-changing target near-field phase distribution includes:
determining far-field amplitude and phase distribution according to the far-field beam information, and performing fast Fourier inverse transformation on the far-field amplitude and phase distribution to obtain near-field amplitude and phase distribution;
replacing the amplitude distribution in the near-field amplitude-phase distribution with Gaussian distribution to obtain updated near-field amplitude-phase distribution;
performing fast Fourier transform according to the updated near-field amplitude-phase distribution to obtain updated far-field amplitude-phase distribution;
and judging whether the updated near-field amplitude-phase distribution and the updated far-field amplitude-phase distribution both meet a preset target, if not, taking the updated far-field amplitude-phase distribution as the far-field amplitude-phase distribution, continuously performing the step of performing inverse fast Fourier transform on the far-field amplitude-phase distribution to obtain the near-field amplitude-phase distribution until the updated near-field amplitude-phase distribution and the updated far-field amplitude-phase distribution both meet the preset target, and determining the target near-field phase distribution according to the finally obtained phase distribution in the updated near-field amplitude-phase distribution.
8. The method of claim 6, wherein the determining the first codebook comprises:
determining a plurality of row vectors according to the target near-field phase distribution, wherein different row vectors respectively correspond to different x-direction assignment weights, and the x-direction assignment weights are used for reflecting the x-direction arrival angle after the incoming wave is reflected;
and determining the first codebook according to each row vector.
9. The method of claim 8, wherein the determining the second codebook comprises:
determining a plurality of column vectors according to the target near-field phase distribution, wherein different column vectors respectively correspond to different y-direction assignment weights, and the y-direction assignment weights are used for reflecting the y-direction arrival angle after the incoming wave is reflected;
and determining the second codebook according to each column vector.
10. The method of claim 9, wherein the phase adjustment data is bias distribution data, and the determining the phase adjustment data corresponding to the reflection front according to the incoming wave direction angle and the target codebook comprises:
determining a target row vector according to the target x-direction incoming wave angle and the first codebook;
determining a target column vector according to the target y-direction incoming wave angle and the second codebook;
determining the weight distribution of the reflecting array surface corresponding to the weight of the array surface according to the assignment weights respectively corresponding to the target row vector and the target column vector;
and determining the bias distribution data according to the weight distribution of the array surface.
11. A base station in communication with an intelligent reflective surface, the intelligent reflective surface including a reflective front in a central region and a plurality of angle sensing elements distributed around the reflective front, the base station comprising:
an obtaining module, configured to obtain a received signal and a local oscillator signal corresponding to each of the angle sensing units, where the received signal of each of the angle sensing units is from a user terminal, and different user terminals correspond to different local oscillator frequencies respectively;
the frequency mixing module is used for respectively carrying out frequency mixing on each received signal according to the local oscillator signal to obtain frequency mixing signals respectively corresponding to the angle sensing units;
the determining module is used for determining an incoming wave direction angle according to each mixing signal;
and the adjusting module is used for acquiring a target codebook and determining phase adjusting data corresponding to the reflection wavefront according to the incoming wave direction angle and the target codebook, wherein the target codebook is used for reflecting phase responses corresponding to different units on the reflection wavefront respectively.
12. An intelligent reflecting surface capable of being spatially multiplexed is characterized by comprising a reflecting front positioned in a central area, a plurality of angle sensing units distributed around the reflecting front and a regulating and controlling module, wherein the regulating and controlling module is respectively connected with the reflecting front and each angle sensing unit;
each angle sensing unit is configured to acquire a signal sent by a user terminal, obtain a received signal, and send the received signal to the base station according to claim 11;
the reflection array surface is used for acquiring phase adjustment data generated by the base station based on the received signals respectively corresponding to the angle sensing units.
13. A mobile communication system, characterized in that the system comprises a user terminal, a base station as claimed in claim 11 and a spatially reusable intelligent reflecting surface as claimed in claim 12.
14. A computer-readable storage medium having stored thereon a plurality of instructions adapted to be loaded and executed by a processor to perform the steps of the method for adjusting phase of a spatially-multiplexed intelligent reflective surface of any of claims 1-10.
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