CN111131096B - Wireless relay system based on programmable super surface and channel estimation method thereof - Google Patents
Wireless relay system based on programmable super surface and channel estimation method thereof Download PDFInfo
- Publication number
- CN111131096B CN111131096B CN201911218634.3A CN201911218634A CN111131096B CN 111131096 B CN111131096 B CN 111131096B CN 201911218634 A CN201911218634 A CN 201911218634A CN 111131096 B CN111131096 B CN 111131096B
- Authority
- CN
- China
- Prior art keywords
- super surface
- base station
- programmable
- wireless relay
- programmable super
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 30
- 230000005540 biological transmission Effects 0.000 claims abstract description 22
- 238000012545 processing Methods 0.000 claims description 24
- 238000005457 optimization Methods 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 11
- 238000013507 mapping Methods 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 238000009432 framing Methods 0.000 claims description 8
- 239000011159 matrix material Substances 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 6
- 230000000750 progressive effect Effects 0.000 claims description 4
- 238000012935 Averaging Methods 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- 238000004891 communication Methods 0.000 abstract description 18
- 230000008569 process Effects 0.000 description 5
- 238000004422 calculation algorithm Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 238000010295 mobile communication Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000012966 insertion method Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 230000008685 targeting Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/024—Channel estimation channel estimation algorithms
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/155—Ground-based stations
- H04B7/15592—Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Radio Relay Systems (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The invention discloses a wireless relay system based on a programmable super surface and a channel estimation method thereof. In the uplink, a frame structure is designed, and pilot frequency segments are inserted in different time slots and positions to perform channel estimation so as to acquire channel information. In the time slot 1, a single tone carrier signal is emitted to a super surface, the reflection coefficient of the super surface is changed according to a time domain control sequence generated by a first section of pilot frequency, a modulated radio frequency signal is reflected, and a channel value from a relay end to a base station end is estimated at the base station end; the time slot 2 super-surface phase is set to be full-through, the base station end estimates a cascade channel according to a second section of pilot frequency sent by the user end, two sections of channel values are obtained at the base station end, and a feedback link can realize information feedback from the base station to the super-surface and time sequence synchronization; and the time slot 3 completes beam forming based on the super-surface relay, so that the communication transmission quality is improved.
Description
Technical Field
The invention relates to a programmable super-surface-based wireless relay system and a channel estimation method thereof, belonging to the technical field of communication.
Background
Since the 21 st century, the demand for mobile communication data volume has increased explosively, and the demand for mobile communication data volume has pushed the development of the whole wireless communication system. In the last decade, the development of new material technology and mobile communication technology, such as artificial electromagnetic surfaces (Metasurfaces), has been receiving attention from researchers due to their unique physical properties. There are many applications of the super-surface in many fields such as digital imaging, electromagnetism and radar. Meanwhile, researches show that the digital programmable super surface can carry information through coding regulation and control, and the possibility of combination between the electromagnetic super surface and wireless communication is provided. On the other hand, in the field of conventional communications, scientists are constantly striving to provide higher quality of service (QoS) between wireless channels. And there is also an increasing concern about energy efficiency in wireless communications. One approach to solving QoS and energy problems is by enhancing control over the propagation environment to mitigate or eliminate undesirable scattering conditions.
In this context, programmable metasurfaces have attracted a great deal of attention in both academia and industry. The programmable super surface is an artificial composite material and is formed by combining a series of artificial unit structures with sub-wavelength sizes. These units interact with electromagnetic waves in a specific way, have unique properties different from natural materials, and can produce unconventional physical phenomena such as negative refraction, perfect lenses, and electromagnetic stealth. Due to the near-passive, low cost and intelligently adjustable reflective properties of programmable super-surfaces, an economical and simple solution to QoS and energy efficiency problems is provided, and more scientists are trying to use them in wireless communication systems.
In conventional solutions, a relay device is widely used in a wireless communication system to enhance the coverage of a signal and reduce the probability of interruption, so as to provide a reliable communication service. Common relay devices include amplify-and-forward relays, decode-and-forward relays, and the like. However, due to the disadvantages of high price, complex architecture, high energy consumption, etc., the requirement of the future wireless communication system cannot be met, and a more efficient and flexible alternative scheme is urgently needed in the industry. Due to the advantages of low cost, simple modulation mechanism, convenient deployment and the like, the programmable super surface is hopeful to replace complicated relay equipment in a specific scene, thereby greatly reducing the energy consumption and equipment cost of the system and providing great possibility for the development of future wireless communication.
However, deployment of programmable super surfaces also faces certain difficulties. For example, due to the simple structure of the programmable super surface and the close passive hardware limit, the programmable super surface can only passively reflect signals but cannot actively receive the signals, so that the data processing capability of the programmable super surface is far less than that of the widely-used amplifying and forwarding repeater, and the complex task of channel estimation cannot be completed. However, in the plc system, the channel values from the ue to the plc are estimated separately, and the channel values from the plc to the bs are particularly important. In particular, the programmable super-surface can change the reflection direction of the emitted electromagnetic waves by changing the reflection coefficient of its surface elements, thereby achieving effective beam forming. This requires obtaining the channel values between the user terminal-programmable super surface, and the programmable super surface-base station terminal, respectively, for the programmable super surface to generate the control signal of the reflection coefficient of the unit to adjust the reflection coefficient of its own surface, so a feasible solution is needed to solve the above problems.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a wireless relay system based on a programmable super surface, which provides a new architecture for relay transmission by using the programmable super surface for wireless communication while avoiding using traditional relay equipment with complex hardware and high cost. Meanwhile, the programmable super surface has a simple structure and is close to a passive surface, so that the programmable super surface can only reflect and cannot receive electromagnetic waves, channel State Information (CSI) is difficult to obtain, and the programmable super surface cannot be effectively utilized to realize beam forming so as to improve the transmission quality of a system and reduce energy consumption.
The invention adopts the following technical scheme for solving the technical problems:
a wireless relay system based on a programmable super surface is composed of a user terminal, a base station terminal and a wireless relay terminal based on the programmable super surface.
The user side comprises a user side baseband processing module, a radio frequency link module and a transmitting antenna; the user side baseband processing module is used for firstly mapping user data into bit stream information consisting of numbers 0 and 1, then mapping the bit stream information into a group of constellation point sets, and finally framing a second section of pilot frequency information and the constellation point sets formed by mapping the user data together to obtain modulated baseband signals; the radio frequency link module is used for up-converting each frame of modulated baseband signals to radio frequency, generating modulated radio frequency signals and sending the modulated radio frequency signals to a transmitting antenna; the transmitting antenna is used for transmitting modulated radio frequency signals and carrying out air interface transmission;
the wireless relay terminal based on the programmable super surface comprises the programmable super surface, a carrier signal generator and a feedback link connected with a base station terminal; the programmable super surface consists of a super surface panel and a control circuit, wherein the super surface panel consists of a plurality of super material units, and each super material unit consists of a variable capacitor, a base material, square metal and annular metal; the super surface panel is used for reflecting modulated radio frequency signals transmitted by a user side; the control circuit generates a section of time domain control sequence according to the first section of pilot frequency information prestored on a register of the control circuit, and the reflection coefficient of the super-surface panel is changed under the control of the time domain control sequence; the carrier signal generator is used for directionally radiating a single-tone carrier signal with preset frequency to the super-surface panel as an incident wave; the feedback link is used for mutual transmission of data signals between the programmable super surface and the base station end, feeding back a channel value estimated by the base station end to the programmable super surface, and completing time sequence synchronization of the base station end and the wireless relay end based on the programmable super surface;
the base station end comprises a receiving antenna, a radio frequency module and a base station end band processing module; the receiving antenna is used for receiving the modulated radio frequency signal reflected by the programmable super surface from the air interface; the radio frequency module is used for carrying out down-conversion on the modulated radio frequency signal received by the receiving antenna and carrying out analog-to-digital conversion to obtain a baseband signal; the base station end baseband processing module is used for processing baseband signals, wherein the processing is to perform channel estimation by using pilot frequency information, perform signal equalization on user data, and finally recover original bit stream information sent by a user end.
Further, the ue can be extended from single antenna to single user to single antenna and multi-user mode.
Further, the relay device based on the programmable super surface selects two modes of distribution and centralization according to requirements: in the centralized type, the programmable super surface takes the form of a single panel; in the distributed mode, the programmable super surface takes the form of a multi-panel.
A channel estimation method based on programmable super surface wireless relay system is based on uplink transmission link composed of user terminal, base station terminal and programmable super surface wireless relay terminal, including the following steps:
step 1, completing preparation of user data and pilot frequency information, wherein the pilot frequency information comprises a first section and a second section;
a user side: the user end baseband processing module maps user data to be transmitted into bit stream information consisting of numbers 0 and 1, then maps the bit stream information into a group of constellation point sets, and then frames a second section of pilot frequency information and the constellation point sets to obtain modulated baseband signals; the radio frequency link module carries out up-conversion on each frame of modulated baseband signals to generate modulated radio frequency signals, and the transmitting antenna transmits the modulated radio frequency signals to carry out air interface transmission;
the wireless relay terminal based on the programmable super surface comprises: the programmable super surface generates a time domain control sequence corresponding to the first section of the pilot frequency information according to the first section of the pilot frequency information stored in the control circuit of the programmable super surface, and the time domain control sequence is used for modulating the incident single tone carrier signal so as to generate and reflect the first section of the pilot frequency signal;
a base station end: reading a first section of pre-stored pilot frequency information for use in channel estimation from a wireless relay end to a base station end based on a programmable super surface; the base station terminal realizes the time sequence synchronization with the wireless relay based on the programmable super surface through a feedback link of the wireless relay based on the programmable super surface;
step 2, framing and sending
The frame structure is divided into 3 time slots in total, wherein the first time slot is used for placing a first section of pilot frequency information, the second time slot is used for placing a second section of the pilot frequency information, and the third time slot is used for placing a group of constellation point sets mapped by user data to be transmitted; the user end frames the second section of the pilot frequency information and a group of constellation point sets mapped by user data to be transmitted, sends the constellation point sets into a radio frequency link module and transmits the constellation point sets through a transmitting antenna;
Monitoring the initial position of a first time slot in each frame of a modulated radio frequency signal sent by a user terminal based on a programmable super-surface wireless relay terminal so as to insert a first section of pilot frequency information, when the first time slot of each frame starts, directionally radiating a single-tone carrier signal with a preset frequency to a super-surface panel as an incident wave through a feed source antenna, performing phase modulation on the single-tone carrier signal through the time domain control sequence in the step 1, reflecting the modulated radio frequency signal of the first section carrying the pilot frequency information by the super-surface panel, and transmitting the modulated radio frequency signal to a base station terminal;
step4, completing channel H from the programmable super surface-based wireless relay terminal to the base station terminal 2 Channel estimation of
After receiving the modulated radio frequency signal of the first section carrying the pilot frequency information at the base station end, the channel estimation from the wireless relay end to the base station end based on the programmable super surface is completed according to the pilot frequency information of the first section prestored at the base station end, and then the estimated value is obtained
Feeding back to the wireless relay terminal based on the programmable super surface through a feedback link;
step 5, completing the channel h from the user terminal to the wireless relay terminal based on the programmable super surface 1 Channel estimation of
The wireless relay terminal based on the programmable super surface comprises: before receiving a modulated radio frequency signal transmitted by a user terminal, the programmable super surface changes the reflection coefficient of the programmable super surface into a full-on state through a control circuit, namely all diagonal elements in a diagonal matrix phi containing phase information of each unit of the programmable super surface are 1;
a base station end: after receiving the modulated radio frequency signal reflected by the programmable super surface at the base station end, finishing the cascade channel estimation of the user end-the wireless relay end based on the programmable super surface-the base station end according to the first section of the pilot frequency information prestored at the base station end to obtain an estimated value
At base station end pair
Left-hand multiplication obtained in step4
Obtaining the channel estimation value from the user terminal to the wireless relay terminal based on the programmable super surface
Then will be
Feeding back to the wireless relay terminal based on the programmable super surface through a feedback link;
step 6, utilizing the channel estimation value in the step 5
Adjusting the reflection coefficient of each metamaterial unit in the super-surface panel to perform beam forming
The wireless relay terminal based on the programmable super surface terminal comprises: using in steps 4, 5
And
changing the reflection coefficient of each metamaterial unit in the super-surface panel, and carrying out beam forming on user data to be transmitted in the reflected modulated radio frequency signals;
a base station end: and carrying out signal equalization on the received user data to be transmitted after the beam forming and then restoring corresponding bit stream information.
Further, by using the reciprocity of uplink and downlink channels in a Time Division Duplex (TDD) system, a guard interval and a downlink data transmission timeslot are added to the frame structure in step 2.
Further, the method for changing the reflection coefficient of each metamaterial unit in the super-surface panel in the step 6 is as follows:
6.1, constructing an optimization problem aiming at maximizing the achievable rate R of the system:
in the formula,
the phase of the reflection of the mth metamaterial unit of the programmable metamaterial surface, M is the total number of the metamaterial units,
6.2 according to H 2 And h 1 Is estimated value of
And
the optimization problem in simplification 6.1 is:
in the formula,
n is the number of antennas at the base station end;
6.3, order
The optimization problem in simplification 6.2 is:
in the formula, real {. Is } represents a real part;
6.4, general purposeObtaining a group by the following steps
Progressive optimal solution of (a):
step 1. Randomly setting a group
A value of (d);
step 2. Use of the method in Step 1
Optimization of
Order to
Then
Of (2) an optimal solution
Thereby obtaining the corresponding system reachable speed R 1 ；
Step4, repeating Step 2 to Step 3 until the ratio of the reachable rate of the system is less than 10 -4 ；
Step 5. Setting different random
Repeating Step 2 to Step4 to obtain a group of optimization results in the form of multiple averaging
And corresponding achievable rate R opt 。
Compared with the prior art, the invention adopting the technical scheme has the following technical effects:
1. the programmable super surface is used for replacing the traditional amplifying forwarding, decoding forwarding and the like as relay equipment in a wireless communication system, and an auxiliary link is provided by reflecting signals through the programmable super surface which is approximate to a passive and low in cost, so that the communication quality between a user and a base station end is ensured;
2. in the generation process of the first-stage pilot frequency, a single-tone carrier is incident to the programmable super surface, and the reflection coefficient of the programmable super surface is regulated and controlled by using a control signal, so that carrier modulation is realized, and reflected waves present the spectral characteristics of a modulated signal carrying the first-stage pilot frequency signal. The scheme sends the first section of pilot frequency data signal through the programmable super surface, and the signal energy basically comes from a single tone carrier wave, so that the energy consumption can be effectively reduced;
3. the scheme adopts a two-section pilot frequency design, simplifies the estimation of two complicated channel values into the estimation of one section of channel and the estimation of the cascade channel, greatly reduces the algorithm complexity of the cascade channel estimation, and increases the possibility for applying the programmable super surface as a relay solution in the future wireless communication.
Drawings
FIG. 1 is a schematic structural diagram of a programmable super surface used in a wireless relay system based on a programmable super surface according to the present invention;
FIG. 2 is a system diagram of a programmable super-surface based wireless relay system according to the present invention;
FIG. 3 is a frame structure diagram of a channel estimation method in a wireless relay system based on a programmable super surface according to the present invention;
FIG. 4 is a schematic flow chart of a channel estimation method in a wireless relay system based on a programmable super surface according to the present invention;
fig. 5 is a schematic data transmission diagram of the channel estimation method in the wireless relay system based on the programmable super surface according to the present invention.
Detailed Description
The technical scheme of the invention is further explained in detail by combining the attached drawings:
the super-surface panel of the programmable super-surface in the invention is composed of a plurality of super-material units as shown in figure 1. The metamaterial unit is composed of a variable capacitor, a base material, square metal and annular metal.
As shown in fig. 2, the present invention provides a wireless relay system based on a programmable super surface and a channel estimation method thereof, the system is based on a wireless communication uplink transmission system including a user terminal, a receiving terminal and a programmable super surface as a relay station, the whole estimation method comprises four stages of data preparation and framing transmission at the user terminal, insertion of pilot information at the programmable super surface in a first stage, channel estimation at the base station terminal twice, feedback of a progressive optimal phase to the programmable super surface for beamforming, and the like.
The wireless relay system based on the programmable super surface specifically comprises:
the user terminal comprises a user terminal baseband processing module, a radio frequency link and a transmitting antenna. The user side baseband processing module is used for mapping user data into bit stream information consisting of numbers 0 and 1, mapping the bit stream information into a group of constellation point sets, and framing a second section of pilot frequency information together with the user data; the radio frequency link is used for up-converting the modulated baseband signals in each frame to radio frequency, generating modulated radio frequency signals and sending the modulated radio frequency signals to a transmitting antenna; and the transmitting antenna is used for transmitting the modulated radio frequency signal and carrying out air interface transmission. The user terminal can be expanded from a single antenna and a single user to a single antenna and multi-user mode.
The relay device based on the programmable super surface comprises the programmable super surface, a carrier signal generator and a feedback link connected with a base station end. The programmable super surface consists of a super surface panel and a control circuit, wherein the super surface panel is used for reflecting modulated radio frequency signals carrying user data transmitted by a user side; the control circuit generates a section of time domain control sequence according to the first section of pilot frequency information pre-stored in a register of the control circuit, and under the control of the time domain control sequence, the reflection coefficient of the super-surface panel is changed, so that the purpose of modulating the phase of the reflected radio frequency signal can be achieved; the carrier signal generator is used for directionally radiating a single-tone carrier signal with preset frequency to the super-surface panel as an incident wave; and the feedback link connected with the base station end is used for carrying out mutual transmission of data signals between the programmable super surface and the base station end, feeding back a channel value estimated by the base station end to the programmable super surface and completing the time sequence synchronization of the base station end and the relay end based on the programmable super surface. The relay device based on the programmable super surface selects a distributed mode and a centralized mode as required: in the centralized type, the programmable super surface takes the form of a single panel; in the distributed mode, the programmable super surface takes the form of a multi-panel.
The base station end comprises a receiving antenna, a radio frequency module and a base station end band processing module. The receiving antenna is used for receiving modulated radio frequency signals reflected by the programmable super surface from an air interface; the radio frequency module is used for carrying out down-conversion on the radio frequency signal and carrying out analog-to-digital conversion to obtain a baseband signal; the base station end baseband processing module is used for processing baseband signals, namely performing channel estimation by using pilot frequency data, performing signal equalization on user data, and finally recovering original bit stream information sent by a user end.
The invention also provides a channel estimation method based on the programmable super surface in the wireless relay system, which is based on an uplink transmission link consisting of a user terminal, a base station terminal and the programmable super surface as a relay station, and comprises the following steps:
step 1, completing preparation of data and pilot frequency information, wherein the pilot frequency information is divided into a first section and a second section, the functions of the two sections are different, and the two sections are stored in different time slots of a frame structure.
A user side: the baseband processing module maps the second section of the pilot frequency information and the user data to be transmitted into bit stream information consisting of numbers 0 and 1, maps the bit stream information into a group of constellation point sets, and frames the second section of the pilot frequency information and the constellation point sets to obtain modulated baseband modulation signals; the radio frequency link module up-converts each frame of modulated baseband signal to generate a modulated radio frequency signal, and the transmitting antenna transmits the modulated radio frequency signal for air interface transmission.
The wireless relay terminal based on the programmable super surface comprises: the programmable super-surface generates a segment of corresponding time domain control sequence based on a first segment of pilot information stored in its control circuitry for modulating an incident single tone carrier signal to generate and reflect the first segment of pilot information.
A base station end: reading a first section of pre-stored pilot frequency information for use in channel estimation from a wireless relay end to a base station end based on a programmable super surface; and the base station terminal realizes the time sequence synchronization with the wireless relay terminal based on the programmable super surface through a feedback link.
And 2, framing and sending according to a design scheme.
The frame structure designed by the invention is divided into 3 time slots, wherein the first time slot is used for placing the first section of pilot frequency information and inserting the first section of pilot frequency information into the wireless relay terminal based on the programmable super surface so as to be used for channel estimation from the wireless relay terminal based on the programmable super surface to the base station terminal; the second time slot is used for placing a second section of pilot frequency information configured by the user side, inserting the second section of pilot frequency information into the user side and estimating a cascade channel of the user side, the programmable super surface and the base station side; and the third time slot is used for placing the user data to be transmitted after constellation mapping. And after framing is finished, the frame can be sent to a radio frequency link for transmission.
And 3, inserting a first section of pilot frequency information based on the wireless relay terminal of the programmable super surface.
The method comprises the steps that a wireless relay terminal based on a programmable super surface monitors the initial position of a first time slot in each frame of a modulated radio frequency signal sent by a user side so as to insert a first section of pilot frequency information, when the first time slot of each frame starts, a single tone carrier signal with preset frequency is used as incident wave to the programmable super surface terminal through a feed source antenna, the phase modulation is carried out on the single tone carrier signal through a time domain control sequence in the step 1, and a super surface panel reflects the modulated radio frequency signal of the first section carrying the pilot frequency information and transmits the modulated radio frequency signal to a base station terminal.
Step4, completing the channel H from the wireless relay terminal to the base station terminal based on the programmable super surface 2 The channel estimation of (2).
After receiving the first section of modulated radio frequency signal carrying pilot frequency information at the base station end, the channel estimation from the programmable super surface end to the base station end can be completed according to the pre-stored pilot frequency information (Least Square (LS) estimation can be adopted), and then the estimation value can be obtained
Feeding back a feedback link connected with the wireless relay terminal based on the programmable super surface through the base station terminal to the wireless relay terminal based on the programmable super surface;
step 5, completing the channel h from the user terminal to the wireless relay terminal based on the programmable super surface 1 The channel value estimate of (2).
The wireless relay terminal based on the programmable super surface comprises: in the second slot of each frame, a second segment of pilot information is transmitted by the subscriber station. Before the programmable super surface receives the second section of pilot frequency, the reflection coefficient of the surface of the programmable super surface is changed into a full-pass state (phi is a diagonal array containing phase information of each unit of the programmable super surface, wherein each diagonal element corresponds to a reflection phase value of one unit, and the full-pass state is that all diagonal elements in the phi are set to be 1), so that the amplitude and the phase of the second section of the pilot frequency information are not influenced by the reflection of the programmable super surface.
A base station end: after receiving the modulated radio frequency signal reflected by the programmable super surface at the base station end, the cascade channel estimation (which can adopt Least Square (LS) estimation) of the user end-the wireless relay end based on the programmable super surface-the base station end can be completed according to the first section of the pre-stored pilot frequency information, and an estimation value is obtained
Because the phase information matrix phi of each unit at the programmable super surface end is a unit matrix in the process of reflecting the second-stage pilot frequency, namely
At the base station end, the obtained cascade channel estimation value is multiplied by H obtained in the step4 2 Inverse of the estimate (if not square, then left-hand multiplied by H) 2 Left pseudo inverse) of the time domain, namely obtaining a channel estimation value between a transmitting end and a wireless relay end based on the programmable super surface
Then, the estimated value is calculated
And feeding back to the wireless relay terminal based on the programmable super surface through a feedback link between the base station terminal and the wireless relay terminal based on the programmable super surface.
And 6, adjusting the reflection coefficient of each unit of the programmable super surface by using the channel estimation result so as to carry out beam forming.
The wireless relay terminal based on the programmable super surface comprises: in time slot 3, the user data to be transmitted is reflected, using H estimated in steps 4 and 5 2 And h 1 Changing the reflection coefficient of each unit of the programmable super surface, and carrying out beam forming on the reflected user data to be transmitted, thereby further improving the system throughput rate.
One way to vary the reflectance of each element of the programmable super-surface is as follows:
for the system model, the system achievable rate is
Where P is the antenna power at the transmitting end, σ n Is the noise power of the system. With the goal of maximizing the achievable rate R, one can obtain
The optimization problem targeting maximizing the achievable rate R is equivalent to
Wherein,
the reflection phase of the mth metamaterial unit on the programmable metamaterial unit, and M is the total number of the metamaterial units.
Get channel H 2 And h 1 Is estimated by
And
then, the channel matrix can be processed
And
and the programmable super-surface phase matrix phi is respectively represented as
Wherein N is the number of antennas at the base station end.
Further expanding, obtaining after matrix multiplication
Let a be n,m ＝x n,m y m Can obtain
Thus, the optimization problem of the phase matrix can be simplified to
For any one
Order to
The above formula can be further simplified into
It can be seen that the values of the first two terms are equal in magnitude to
Independently, the maximum value can be reached only by setting the complex argument in the bracket of the real part of the third term to zero. So for each one
In the case of reflection phase determination of the rest metamaterial units of the programmable super surface, the optimal value is
Therefore, a set of algorithms can be obtained by the following algorithm
The progressive optimal solution of (2).
Step 1. Randomly setting a group
A value of (d);
step 2. Use of the method in Step 1
Optimization
Order to
Based on the above derivation, i.e.
Optimal solution of
Find out
Post-entry to obtain corresponding system reachable rate R 1 ；
And Step4, iterating Step 2 to Step 3 for a plurality of times until the ratio of the reachable rate of the system is less than 10 -4 Stopping the iteration;
step 5, setting different random initial phases
Repeating Step 2 to Step4 for several times (for example, set to 10000 times), and finally obtaining a group of optimization results in the form of multiple averaging
And finally the corresponding achievable rate R opt 。
So far, the algorithm is used for obtaining the progressive optimal phase value of each metamaterial unit of the programmable super surface
By connecting base station terminals with programmable super-surface terminalsThe feedback link can transmit the obtained phase value back to the programmable super surface, and the reflection coefficient of the programmable super surface is adjusted through a control circuit of the feedback link to complete beam forming.
A base station end: after receiving the user data to be transmitted in the time slot 3, the base station performs signal equalization on the user data, and then can recover the original bit stream information sent by the user terminal.
The invention adopts the programmable super surface to replace the traditional relay equipment, the relay end is completely composed of the programmable super surface with low price, simple structure and easy deployment and a control link thereof, and in addition, the information interaction and the time sequence synchronization of the relay end and the base station end can be realized through the feedback control link. Due to the limited data processing capacity of the programmable super surface, the state information of two sections of channels is difficult to obtain, and the intelligent reflection effect of the programmable super surface on incident waves cannot be exerted to the maximum extent. Therefore, the present invention is based on the problem of utilizing the frame structure of the dual pilot mode to acquire the channel state information.
When the first section of the pilot frequency information is loaded, the programmable super surface controls the phase of the single-tone carrier wave by changing the reflection coefficient of each metamaterial unit through a time sequence control sequence, the reflection process can be regarded as a novel modulation process, the modulated carrier wave signal loaded with the pilot frequency information is obtained, a complex mixer, power amplification equipment and the like are not needed, all energy is almost concentrated on the carrier wave signal, and the power consumption is reduced. Meanwhile, in the process of relaying signals, compared with the defect of noise amplification caused by amplification and forwarding, the programmable super surface only changes the phase of incident waves and does not introduce radio frequency link noise. Compared with the defects that complex modules such as receiving, demodulating, retransmitting and the like are needed in decoding and forwarding, the programmable super surface only reflects incident waves, the requirement on data processing capacity is low, and the deployment cost and the link complexity are reduced.
In summary, the invention adopts a programmable super surface to replace the traditional relay device, and the reflection coefficient of each unit of the programmable super surface is controlled to intelligently reflect the incident wave to generate the required radio frequency signal, so that the traditional relay devices with complicated design and high cost, such as decoding forwarding, amplifying forwarding and the like, are avoided at the relay device end, thereby greatly reducing the deployment cost and improving the flexibility of the system architecture. The two-section type pilot frequency insertion method designed by the invention can effectively estimate two-section channel values, further carry out reasonable beam forming at the programmable super-surface relay end, and reduce the difficulty in estimating the cascade channel and the pilot frequency overhead to a certain extent. The system widens the concept of the traditional wireless communication system, and converts the complex and heavy relay equipment deployment into the simple and flexible programmable super-surface configuration. The system utilizes the programmable super surface which is approximate to the passive and low in cost as the relay equipment and designs a frame structure to further complete the estimation of two sections of channels, and completes the return and update of the channel state information through controlling the feedback circuit, thereby carrying out beam forming at the programmable super surface end and improving the communication quality. The method provides a new idea for solving the problems of weak data processing capacity and difficult channel estimation in the actual deployment of the programmable super surface, and increases the possibility for widely applying the programmable super surface in a new generation of mobile communication system.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Claims (6)
1. The wireless relay system based on the programmable super surface is composed of a user terminal, a base station terminal and a wireless relay terminal based on the programmable super surface, and is characterized in that:
the user side comprises a user side baseband processing module, a radio frequency link module and a transmitting antenna; the user side baseband processing module is used for firstly mapping user data into bit stream information consisting of numbers 0 and 1, then mapping the bit stream information into a group of constellation point sets, and finally framing a second section of pilot frequency information and the constellation point sets formed by mapping the user data together to obtain modulated baseband signals; the radio frequency link module is used for up-converting each frame of modulated baseband signals to radio frequency, generating modulated radio frequency signals and sending the modulated radio frequency signals to a transmitting antenna; the transmitting antenna is used for transmitting modulated radio frequency signals and carrying out air interface transmission;
the wireless relay terminal based on the programmable super surface comprises the programmable super surface, a carrier signal generator and a feedback link connected with a base station terminal; the programmable super surface consists of a super surface panel and a control circuit, wherein the super surface panel consists of a plurality of super material units, and each super material unit consists of a variable capacitor, a base material, square metal and annular metal; the super surface panel is used for reflecting modulated radio frequency signals transmitted by a user side; the control circuit generates a section of time domain control sequence according to the first section of pilot frequency information prestored in the register of the control circuit, and changes the reflection coefficient of the super-surface panel under the control of the time domain control sequence; the carrier signal generator is used for directionally radiating a single-tone carrier signal with preset frequency to the super-surface panel as an incident wave; the feedback link is used for mutual transmission of data signals between the programmable super surface and the base station end, feeding back a channel value estimated by the base station end to the programmable super surface, and completing time sequence synchronization of the base station end and the wireless relay end based on the programmable super surface;
the base station end comprises a receiving antenna, a radio frequency module and a base station end band processing module; the receiving antenna is used for receiving a modulated radio frequency signal reflected by the wireless relay terminal based on the programmable super surface from an air interface; the radio frequency module is used for carrying out down-conversion on the modulated radio frequency signal received by the receiving antenna and carrying out analog-to-digital conversion to obtain a baseband signal; the base station end baseband processing module is used for processing baseband signals, wherein the processing is to perform channel estimation by using pilot frequency information, perform signal equalization on user data and finally recover original bit stream information sent by a user end.
2. The programmable super surface based wireless relay system of claim 1, wherein said user side is extendable from single antenna single user to single antenna multi-user mode.
3. The programmable super surface based wireless relay system of claim 1, wherein the programmable super surface based relay device selects two modes of distributed and centralized as required: in the centralized type, the programmable super surface takes the form of a single panel; in the distributed mode, the programmable super surface takes the form of a multi-panel.
4. The method for channel estimation in a wireless relay system based on programmable super surface as claimed in claim 1, the method is based on uplink transmission link consisting of user terminal, base station terminal and wireless relay terminal based on programmable super surface, comprising the steps of:
step 1, completing the preparation of user data and pilot frequency information, wherein the pilot frequency information comprises a first section and a second section
A user side: the user end baseband processing module maps user data to be transmitted into bit stream information consisting of numbers 0 and 1, then maps the bit stream information into a group of constellation point sets, and then frames a second section of pilot frequency information with the constellation point sets to obtain modulated baseband signals; the radio frequency link module carries out up-conversion on each frame of modulated baseband signals to generate modulated radio frequency signals, and the transmitting antenna transmits the modulated radio frequency signals to carry out air interface transmission;
the wireless relay terminal based on the programmable super surface comprises: the programmable super surface generates a time domain control sequence corresponding to the first section of the pilot frequency information according to the first section of the pilot frequency information stored in the control circuit of the programmable super surface, and the time domain control sequence is used for modulating the incident single tone carrier signal so as to generate and reflect the first section of the pilot frequency signal;
a base station end: reading a first section of pre-stored pilot frequency information for use in channel estimation from a wireless relay end to a base station end based on a programmable super surface; the base station terminal realizes the time sequence synchronization with the wireless relay based on the programmable super surface through a feedback link of the wireless relay based on the programmable super surface;
step 2, framing and sending
The frame structure is divided into 3 time slots, the first time slot is used for placing a first section of pilot frequency information, the second time slot is used for placing a second section of pilot frequency information, and the third time slot is used for placing a group of constellation point sets mapped by user data to be transmitted; the user end frames the second section of the pilot frequency information and a group of constellation point sets mapped by user data to be transmitted, sends the constellation point sets into a radio frequency link module, and then carries out air interface transmission through a transmitting antenna;
step 3, inserting a first section of pilot frequency information into the wireless relay terminal based on the programmable super surface
Monitoring the initial position of a first time slot in each frame of a modulated radio frequency signal sent by a user terminal based on a programmable super-surface wireless relay terminal so as to insert a first section of pilot frequency information, when the first time slot of each frame starts, directionally radiating a single-tone carrier signal with a preset frequency to a super-surface panel as an incident wave through a feed source antenna, performing phase modulation on the single-tone carrier signal through the time domain control sequence in the step 1, reflecting the modulated radio frequency signal of the first section carrying the pilot frequency information by the super-surface panel, and transmitting the modulated radio frequency signal to a base station terminal;
step4, completing channel H from the programmable super surface-based wireless relay terminal to the base station terminal 2 By a channel estimation method
After receiving the modulated radio frequency signal of the first section carrying the pilot frequency information at the base station end, the base station end completes the channel estimation from the wireless relay end to the base station end based on the programmable super surface according to the pilot frequency information of the first section prestored at the base station end, and then the estimated value is obtained
Feeding back to the wireless relay terminal based on the programmable super surface through a feedback link;
step 5, completing the channel h from the user terminal to the wireless relay terminal based on the programmable super surface 1 Channel estimation of
The wireless relay terminal based on the programmable super surface comprises: before receiving a modulated radio frequency signal transmitted by a user terminal, the programmable super surface changes the reflection coefficient of the programmable super surface into a full-on state through a control circuit, namely all diagonal elements in a diagonal matrix phi containing phase information of each unit of the programmable super surface are 1; wherein
The reflection phase of the mth metamaterial unit of the programmable metamaterial surface, wherein M is the total number of the metamaterial units;
a base station end: after receiving the modulated radio frequency signal reflected by the programmable super surface at the base station end, finishing the cascade channel estimation of the user end-the wireless relay end based on the programmable super surface-the base station end according to the first section of the pilot frequency information prestored at the base station end to obtain an estimated value
At base station end pair
Left-hand multiplication obtained in step4
Obtaining the channel estimation value from the user terminal to the wireless relay terminal based on the programmable super surface
Then will be
Feeding back to the wireless relay terminal based on the programmable super surface through a feedback link;
step 6, utilizing the channel estimation value in the step 5
Adjusting the reflection coefficient of each metamaterial unit in the super-surface panel to perform beam forming
The wireless relay terminal based on the programmable super surface terminal comprises: using in steps 4, 5
And
changing the reflection coefficient of each metamaterial unit in the super-surface panel, and carrying out beam forming on user data to be transmitted in the reflected modulated radio frequency signals;
a base station end: and after signal equalization is carried out on the received user data to be transmitted after beam forming, corresponding bit stream information is recovered.
5. The method as claimed in claim 4, wherein the uplink and downlink channel reciprocity in the TDD system is used, and a guard interval and a downlink data transmission time slot are added to the frame structure in step 2.
6. A method for channel estimation in a wireless relay system based on programmable meta-surfaces as claimed in claim 4, wherein the method for changing the reflection coefficient of each meta-material unit in the meta-surface panel in step 6 is as follows:
6.1, constructing an optimization problem aiming at maximizing the achievable rate R of the system:
6.2 according to H 2 And h 1 Is estimated by
And
the optimization problem in simplification 6.1 is:
in the formula,
n is the number of antennas of the base station end;
6.3, order
The optimization problem in simplification 6.2 is:
in the formula, real {. Is } represents a real part;
6.4 obtaining a set by the following steps
The progressive optimal solution of (2):
step 1. Randomly setting a group
A value of (d);
step 2. Use of the method in Step 1
Optimization
Order to
Step 3. Using the method of Step 2, the calculation
To obtain the corresponding system reachable rate R 2 ,...,R M ；
Step4, repeating Step 2 to Step 3 until the increase ratio of the reachable rate of the system is less than 10 -4 ；
Step 5. Set different random
Repeating Step 2 to Step4 to obtain a group of optimization results in the form of multiple averaging
And corresponding achievable rate R opt 。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911218634.3A CN111131096B (en) | 2019-12-03 | 2019-12-03 | Wireless relay system based on programmable super surface and channel estimation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911218634.3A CN111131096B (en) | 2019-12-03 | 2019-12-03 | Wireless relay system based on programmable super surface and channel estimation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111131096A CN111131096A (en) | 2020-05-08 |
| CN111131096B true CN111131096B (en) | 2022-10-04 |
Family
ID=70497031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911218634.3A Active CN111131096B (en) | 2019-12-03 | 2019-12-03 | Wireless relay system based on programmable super surface and channel estimation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111131096B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111867054A (en) * | 2020-06-30 | 2020-10-30 | 中兴通讯股份有限公司 | Method, device and system for positioning transmitting device, storage medium and electronic device |
| CN115669108A (en) | 2020-07-02 | 2023-01-31 | 中兴通讯股份有限公司 | Binning and node grouping for intelligent reflective devices |
| US11843171B2 (en) | 2020-08-18 | 2023-12-12 | Samsung Electronics Co., Ltd. | Multi-layer reconfigurable surface for an antenna |
| CN114080036A (en) * | 2020-08-19 | 2022-02-22 | 华为技术有限公司 | Resource allocation method and device |
| CN114584185A (en) * | 2020-12-01 | 2022-06-03 | 华为技术有限公司 | Communication method, device and system |
| CN112735111B (en) * | 2020-12-16 | 2022-04-08 | 中兴通讯股份有限公司 | Intelligent panel regulation and control method, device and system, intelligent panel and storage medium |
| CN112888059B (en) * | 2021-01-13 | 2022-05-17 | 之江实验室 | Intelligent reflector auxiliary communication rapid data transmission protocol |
| CN114362800B (en) * | 2022-01-05 | 2022-10-04 | 浙江大学 | Active and passive information symbiotic transmission method based on discrete phase intelligent super-surface system |
| CN114726684B (en) * | 2022-03-03 | 2024-10-01 | 杭州腓腓科技有限公司 | Channel estimation method and device based on holographic multiple access |
| CN117280662A (en) * | 2022-04-21 | 2023-12-22 | 北京小米移动软件有限公司 | Method and device for acquiring pilot frequency position determining model and pilot frequency position determining method and device |
| CN118393458B (en) * | 2024-06-27 | 2024-09-10 | 东南大学 | Millimeter wave radar anti-interference target detection method and device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108923814A (en) * | 2018-05-29 | 2018-11-30 | 东南大学 | It may be programmed the wireless communications method and system of Meta Materials based on time domain |
| CN110336575A (en) * | 2019-06-19 | 2019-10-15 | 东南大学 | A kind of super surface intelligent processing system of information applied to cell base station wireless communication |
-
2019
- 2019-12-03 CN CN201911218634.3A patent/CN111131096B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN111131096A (en) | 2020-05-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111131096B (en) | Wireless relay system based on programmable super surface and channel estimation method thereof | |
| CN113225108B (en) | Robust beam forming method for intelligent reflector-assisted multi-cell coordinated multi-point transmission | |
| CN110266352B (en) | Self-adaptive design method for intelligent reflecting surface phase shift matrix in large-scale MIMO system | |
| Xu et al. | Resource allocation for active IRS-assisted multiuser communication systems | |
| Havary-Nassab et al. | Optimal distributed beamforming for two-way relay networks | |
| US10432275B2 (en) | Non-line of sight wireless communication system and method | |
| EP0961416A1 (en) | Adaptive array transceiver | |
| CN108713295B (en) | Practical hybrid precoding scheme for multi-user massive MIMO systems | |
| CN105897319B (en) | A kind of MIMO full duplex relaying system information source relaying joint method for precoding | |
| CN114070365B (en) | Intelligent reflection surface assisted low-radio-frequency-complexity multi-user MIMO uplink spectrum efficiency optimization method | |
| CN111901812B (en) | Full-duplex cellular communication network base station and intelligent reflecting surface joint control method | |
| CN113709687A (en) | Intelligent reflector assisted resource allocation method for wireless sensor network | |
| Okandeji et al. | Joint transmit power and relay two-way beamforming optimization for energy-harvesting full-duplex communications | |
| CN113852402B (en) | IRS (intelligent communications system) -assisted NOMA-MIMO (non-multiple input multiple output) high-capacity access method | |
| Mohamed et al. | Resource allocation for energy-efficient cellular communications via aerial IRS | |
| CN114828253A (en) | Resource allocation method of RIS (RIS) assisted multi-unmanned aerial vehicle communication system | |
| Sasaki et al. | Field experimental demonstration on OAM-MIMO wireless transmission on 28 GHz band | |
| Farrag et al. | Sum rate maximization of uplink active RIS and UAV-assisted THz mobile communications | |
| CN116388830A (en) | Communication positioning integrated system and method based on intelligent reflecting surface | |
| WO2003081788A2 (en) | Adaptive beamforming in a wireless communication system | |
| CN114513237B (en) | Subarray structure design method for large-scale array communication | |
| Niu et al. | Interference subspace tracking for network interference alignment in cellular systems | |
| Mao et al. | Iterative Power Control for Wireless Networks with Distributed Reconfigurable Intelligent Surfaces | |
| Singh et al. | A NOMA-enabled hybrid RIS-UAV-aided full-duplex communication system | |
| CN110808767A (en) | Hybrid beam forming design scheme in millimeter wave multi-antenna relay system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |