CN116707601A - A method and device for assisting communication with an intelligent reflective surface - Google Patents
A method and device for assisting communication with an intelligent reflective surface Download PDFInfo
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Abstract
The invention provides an intelligent reflector auxiliary communication method and device, and belongs to the technical field of wireless communication. Aiming at an intelligent reflector auxiliary communication system, the control information transmission cost of an intelligent reflector auxiliary communication method is avoided by using a transparent and reflective integrated intelligent reflector, the convenience and the reusability of an intelligent reflector auxiliary communication device are improved, and the intelligent reflector auxiliary communication method and device are not determined by a base station/terminal to determine a reflection coefficient, but are determined by the intelligent reflector itself and consist of the transparent and reflective integrated intelligent reflector and a control unit; the transparent and reflective integrated intelligent reflecting surface is used for receiving and reflecting signals, and the control unit is used for processing the signals and calculating the reflection coefficient of the transparent and reflective integrated intelligent reflecting surface reflecting array element. The deployment complexity of the intelligent reflector auxiliary communication device is effectively reduced, and the convenience and reusability of the intelligent reflector auxiliary communication device are improved.
Description
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a method and a device for intelligent reflector auxiliary communication.
Background
In the fifth generation wireless network, although the key technologies of Ultra Dense Network (UDN), large-scale Multiple Input Multiple Output (MIMO), millimeter wave communication (mmWave) and the like have been implemented, the key problems of high complexity, high hardware cost, high energy consumption and the like of the system have not been solved yet, so that it is imperative to seek a solution that is energy-saving, innovative and has low cost.
In recent years, as a promising new technology, intelligent reflection surfaces reconfigure wireless environments by software-controlled reflection. The intelligent reflecting surface uses a large number of low-cost passive reflecting elements integrated on a plane, and each element can change the amplitude or the phase of an incident signal, so that three-dimensional fine-granularity reflecting beam forming is cooperatively realized, and more possibilities are provided for signal transmission between a base station and a terminal.
At present, in the research of a method for assisting communication by a smart reflecting surface, how to reasonably make the change of amplitude or phase of an incident signal by the smart reflecting surface is rarely researched.
One common approach is for the base station/terminal to control the reflection coefficient of the intelligent reflective surface, either by wire or wirelessly, to control the change in amplitude or phase of the incident signal by the intelligent reflective surface.
The base station/terminal controls the intelligent reflecting surface in a wired or wireless mode, and the purpose of changing the amplitude or phase of an incident signal can be achieved, but the method requires the base station/terminal to send control information while sending data, so that additional expenditure is brought to the base station/terminal, and the cost of the base station/terminal is increased.
If the control is performed in a wired mode, the complexity of deploying the intelligent reflector auxiliary communication system is increased, and the convenience and reusability of the intelligent reflector auxiliary communication device are reduced.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the method and the device for the auxiliary communication of the intelligent reflecting surface, which can effectively avoid the control information transmission overhead of the auxiliary communication method of the intelligent reflecting surface, reduce the deployment complexity of the auxiliary communication device of the intelligent reflecting surface and increase the convenience and the reusability of the auxiliary communication device of the intelligent reflecting surface.
In order to achieve the above technical purpose, the present invention discloses a method for intelligent reflection surface auxiliary communication, which is applied to a cellular mobile communication system, wherein the system comprises a base station operating in a physical cell, an intelligent reflection surface auxiliary communication device and a plurality of mobile terminals, wherein the intelligent reflection surface auxiliary communication device comprises a transparent and reflective integrated intelligent reflection surface and a control unit, and the transparent and reflective integrated intelligent reflection surface comprises a transmission array element for receiving signals and a reflection array element for reflecting signals. The array elements in the transparent and reflective integrated intelligent reflecting surface can be array elements for realizing transmission or reflection independently, the number of the reflective array elements is far greater than that of the transmissive array elements, and the transmissive array elements are distributed in the central position of the intelligent reflecting surface in a concentrated manner; or an integrated array element with both transmission and reflection functions. The transmission and reflection integrated intelligent reflecting surface is used for receiving and reflecting signals, and the control unit is used for processing the signals and calculating the reflection coefficient of the reflection array element of the transmission and reflection integrated intelligent reflecting surface;
the method comprises the following steps:
step 1, an intelligent reflecting surface auxiliary communication device receives a system message transmitted by a base station, wherein the system message comprises the bandwidth, the frame structure and the center frequency information of a cell;
step 2, the intelligent reflector auxiliary communication device estimates the angle information of an intelligent reflector path of the base station reaching the intelligent reflector auxiliary communication device by using a main synchronization sequence PSS specified by a new air interface (5G NR) of a 5 th generation mobile communication technology;
step 3, the intelligent reflector auxiliary communication device estimates the angle information of the intelligent reflector path of the mobile terminal reaching the intelligent reflector auxiliary communication device by using a Preamble sequence Preamble specified by 5G NR;
step 4, the intelligent reflection surface auxiliary communication device acquires the cell radio network temporary identifier C-RNTI information of the mobile terminal by utilizing a random access process (defined in 5G NR) initiated by the terminal to the base station;
step 5, storing the result obtained in the step 2-4 by using a lookup table; the angle of the base station path is stored separately, and the angle information of the terminal path and the C-RNTI information of the terminal are arranged in a one-to-one correspondence manner;
step 6, the transmission array element of the transmission and reflection integrated intelligent reflecting surface receives signals, detects the incoming wave direction of the signals, judges the signal type according to the signal direction, judges the downlink signals if the signal type is the same as the direction of the base station, and judges the uplink signals if the signal type is the same as the direction of the base station;
step 7, after the transmission and reflection integrated intelligent reflecting surface judges the received signal as a downlink signal, utilizing the stored C-RNTI to try to demodulate the signal, and if the signal demodulation is successful, taking the angle of the path corresponding to the successfully demodulated C-RNTI as a target direction;
step 8, after the transmission and reflection integrated intelligent reflecting surface judges the received signal as an uplink signal, judging that the uplink signal direction can only be the direction of the base station, calculating channel matrixes between the base station and the transmission and reflection integrated intelligent reflecting surface and between the mobile terminal and the transmission and reflection integrated intelligent reflecting surface, and then calculating the reflection coefficient of the transmission and reflection integrated intelligent reflecting surface;
and 9, the control unit configures the reflection array elements of the transparent and reflective integrated intelligent reflecting surface according to the reflection coefficient to realize signal reflection, so that the deployment complexity of the intelligent reflecting surface auxiliary communication device is effectively reduced, and the convenience and reusability of the intelligent reflecting surface auxiliary communication device are improved.
Further, the system message in step 1 includes a synchronization broadcast block SSB, a master system message MIB, and a system message block SIB1.
Further, the basic method for estimating the base station/terminal path angle in step 2 and step 3 is as follows:
taking a primary synchronization sequence PSS/Preamble sequence Preamble as a local sequence, and performing cross correlation between the local sequence and a received signal of each transmission array element of the transmission and reflection integrated intelligent reflecting surface;
combining peaks of different transmission array elements of the transflective integrated intelligent reflecting surface under the same time delay of the time delay domain into column vectors, calculating covariance matrixes of the column vectors, and decomposing eigenvalues to obtain a signal subspace;
and calculating a space spectrum according to the signal subspace, and searching the peak value of the space spectrum to obtain the path angle.
Further, the process of estimating the path angle of the base station to the intelligent reflecting surface by using the primary synchronization sequence PSS is as follows: firstly, determining the time-frequency resource position of a primary synchronization sequence PSS; then, cross-correlating all possible PSS sequences with the received signal through all frequency grids to obtain a frequency offset value and a physical cell identifier 2 of 5G NR; finally, the cross-correlation result of the obtained frequency offset value and the physical cell identifier 2 of 5G NR is utilized to estimate the angle of the base station reaching the intelligent reflecting surface path through the method of claim 3.
Further, the process of estimating the path angle of the terminal to the intelligent reflecting surface by using the Preamble sequence Preamble is as follows: firstly, determining the time-frequency resource position of a Preamble sequence Preamble; then traversing all possible root sequences and all Preamble indexes generated by the root sequences, generating a reference Preamble sequence by using the Preamble indexes, performing cross-correlation on a received signal and the reference Preamble sequence, and further detecting whether the peak value of a correlation peak reaches a certain threshold value; if yes, recording the peak value of the correlation peak, and finally estimating the angle of the terminal reaching the intelligent reflecting surface path by using the method of claim 3; if not, continuing to traverse until the peak value of the detected correlation peak reaches the preset threshold value, and then estimating the path angle.
Further, a random access process initiated by the mobile terminal to the base station is utilized to obtain a terminal C-RNTI, and the steps are as follows:
step 1, when an intelligent reflection surface auxiliary communication device receives a random access Preamble (Msg 1), beam scanning is carried out to obtain a beam for transmitting a physical random access channel PRACH, after receiving the Msg1, an SSB index is determined according to an index between a random access channel PRACH time-frequency resource and a Preamble sequence Preamble and by referring to a 5G NR uplink synchronization process, so that a receiving and transmitting beam pair between a terminal and a base station is determined;
step 2, the intelligent reflection surface auxiliary communication device obtains downlink control information DCI according to the physical downlink control channel PDCCH configuration of the mobile terminal obtained by receiving a system message block SIB1, receives physical downlink shared channel PDSCH transmission (Msg 2) scrambled by a random access radio network temporary identifier RA-RNTI, and obtains an uplink scheduling UL Grant and a temporary cell radio network temporary identifier TC-RNTI (defined in 5G NR) in the Msg 2;
and step 3, the intelligent reflector auxiliary communication device obtains the Physical Uplink Shared Channel (PUSCH) transmission (Msg 3) scheduled by the Msg2 according to the uplink scheduling (UL Grant) in the Msg2 message. Wherein a common control channel service data unit CCCH SDU (defined in 5G NR) in Msg3 is used to verify if it matches a message in a contention-resolved PDSCH transmission (Msg 4), PUSCH is scrambled by a medium TC-RNTI of an Msg2 message, and time-frequency resources are given by UL Grant;
and step 4, the intelligent reflector auxiliary communication device receives the contention resolution identification (MAC layer) control unit Contention Resolution IdentityMAC CE in the Msg4, and considers that the random access is successful and upgrades the TC-RNTI into the C-RNTI when the contention resolution identification (MAC layer) control unit Contention Resolution IdentityMAC CE is matched with the CCCH SDU sent by the Msg 3.
Compared with the prior art, the invention has the beneficial effects that:
the method avoids the control information transmission overhead of the intelligent reflector auxiliary communication method, reduces the deployment complexity of the intelligent reflector auxiliary communication device, and increases the convenience and reusability of the intelligent reflector auxiliary communication device.
Drawings
FIG. 1 is a schematic flow chart of an intelligent reflector auxiliary communication method of the invention;
FIG. 2 is a schematic diagram of a system for intelligent reflector assisted communication in an embodiment of the present invention;
FIG. 3 is a schematic diagram of an implementation method of a transflective integrated intelligent reflecting surface in an embodiment of the present invention;
FIG. 4 is a schematic diagram of another implementation method of a transflective integrated intelligent reflective surface according to an embodiment of the present invention;
Detailed Description
Embodiments of the invention are further described below with reference to the accompanying drawings:
the invention discloses an intelligent reflecting surface auxiliary communication method, which relates to a device used for determining the reflecting coefficient of an intelligent reflecting surface according to an incident signal so as to assist communication.
Referring to fig. 1, fig. 1 is a flowchart of an intelligent reflector auxiliary communication method disclosed in the present invention. Assuming that the intelligent reflector-assisted communication apparatus operates in a physical cell, the intelligent reflector-assisted communication method operates as follows:
s1, receiving a system message to obtain information such as cell bandwidth, frame structure, center frequency and the like
The system messages that need to be received include SSB, MIB and SIB1.
S2, estimating the angle of the base station reaching the intelligent reflecting surface path by using the PSS sequence
In the 5G NR system, a base station periodically transmits SSB for downlink synchronization, and a terminal initiates a random access process to perform uplink synchronization after receiving the SSB.
Wherein, the SSB occupies 4 OFDM symbols in the time domain and occupies 240 subcarriers in the frequency domain, and consists of PSS, secondary Synchronization Sequence (SSS), physical Broadcast Channel (PBCH) and de-reference signal (DM-RS).
The apparatus estimates the angle of arrival of the base station at the intelligent reflector path using the PSS sequence in the SSB.
S3, estimating the angle of the terminal reaching the intelligent reflecting surface path by using the Preamble sequence
The random access procedure is divided into 4 procedures: preamble transmission Msg1, base station response to PRACH Msg2, PUSCH transmission scheduled by Msg2 Msg3, and contention-resolved Physical Downlink Shared Channel (PDSCH) transmission Msg4.
The device utilizes the Preamble to sense the angle of the terminal reaching the intelligent reflecting surface path.
The specific estimation method of the angle of the base station/terminal reaching the intelligent reflecting surface path is as follows:
the Preamble/PSS signal model is solved as follows:
wherein,,is of duration T b Rectangular narrow pulse of b k Representing the pulse amplitude, K representing the length of the sequence, the symbol rate being 1/T b 。
The solution of the base station/mobile terminal-intelligent reflector auxiliary communication device channel model is as follows:
where L is the number of multipaths; h is a l Representing the gain of the first path;representing the phase effect of the channel on the signal; f represents a carrier frequency; τ l Representing the delay of the first path; e (phi) l ,θ l F) can be written in the form:
from the geometrical relationship, the phases of the signals received by the different transmission array elements can be obtained:
v l ＝2πfd sinφ l cosθ l /c，u l ＝2πfd sinθ l /c
fd/c＝0.5fλ max /c＝0.5f/f max
because the central frequency of the intelligent reflecting surface array element on the intelligent reflecting surface auxiliary communication device is 3.5GHz and is far greater than the signal bandwidth, the f/f max And 1. Thus, there are:
v l ＝πsinφ l cosθ，u l ＝πsinθ l
N h is the number of transmission array elements in the horizontal direction of the transparent and reflective integrated intelligent reflecting surface, N v Is the number of the transmission array elements in the vertical direction of the transmission and reflection integrated intelligent reflecting surface.
φ l 、θ l The azimuth and elevation of the first path, respectively.
The received signal model of the intelligent reflector auxiliary communication device is as follows:
wherein m represents a transmission array element, y of the mth intelligent reflecting surface auxiliary communication device m (τ) represents the received signal of the mth transmissive element; s (tau-tau) l ) Representing the time delay tau of the transmitted signal s (tau) l After that, the signals reach the transparent and reflective integrated intelligent reflecting surface; e, e m (φ l ,θ l ) Is the complex steering factor of the m-th array element; our handleMarked as->It represents the complex gain of the first path; n (N) m (τ) represents channel noise, which follows a gaussian distribution.
The received signal and the input signal are cross-correlated, and since the PSS/Preamble has good autocorrelation, there are:
wherein s (τ - τ) l )*s * (-τ)＝KP b δ(τ-τ l )，P b Is the pulse power.
N m (τ)*s * (-τ)＝N′ m (τ)
As can be seen from the formula in [0051], p (τ) has L peaks in the delay domain.
Combining the L peaks of the m-th array element to obtain a row vector, and marking as:
in the transmissive array element of the intelligent reflective surface auxiliary communication device, all peaks are as follows:
the mth row represents the output of the mth array element, and the first row represents the peak value of the first path. Thus, the column of A is referred to as a path array response vector, which corresponds to an independent path.
The path array response vector for the first path may be further expressed as:
e(φ l ,θ l ) Is an M-dimensional steering vector pointing to the angle of arrival of the first path. Our aim was to rely on the observed v l Determination (phi) l ,θ l )。
v l Can be calculated as (for ease of description, neglecting (phi l ,θ l ))：
Readily available, C l Rank is 1 and its eigenvalue is fullFoot support
Then C l Feature vector u of (2) 1 Is a direction vector pointing to the first path, wherein the feature vector u 1 Is a characteristic value lambda 1 The corresponding feature vector.
Thus, there are the following quotients: u (u) 1 Space formed by eigenvectors corresponding to other zero eigenvalues, i.e. u 1 ⊥B R 。B R ＝[u 2 u 3 …… u M ]。
Based on B R Is called C l Is included in the reference subspace of (a). We can therefore derive all steering vectors e (phi) pointing to the first path l ,θ l ) Orthogonal to the reference subspace. The spatial spectrum can thus be defined as follows:
the angle of the path can be obtained by searching the spatial spectrum P (phi, theta) for peaks. When this is done for each path, the angle of each path of the base station/terminal is obtained.
S4, obtaining the C-RNTI of the terminal by utilizing the random access process
The method comprises the following specific steps:
1. when receiving Msg1, the device scans a wave beam to obtain a wave beam for transmitting PRACH. After the reception of the Msg1 is completed, the SSB index is determined by referring to the 5G NR uplink synchronization procedure according to the index between the PRACH time-frequency resource and the Preamble, thereby determining the reception and transmission beam pair between the terminal and the base station.
2. The device obtains DCI according to PDCCH configuration obtained by SIB1, receives PDSCH scrambled by RA-RNTI, and obtains UL Grant and TC-RNTI in Msg 2.
3. The device obtains CCCH SDU of Msg3 according to UL Grant in Msg2 message, which is used to verify whether the CCCH SDU matches with message in Msg4, wherein PUSCH is scrambled by TC-RNTI in Msg2 message, and time frequency resource is given by UL Grant.
4. Contention Resolution Identity MAC CE in Msg4 is received, and when the received random access matches with CCCH SDU sent by Msg3, the random access is considered successful and the TC-RNTI is upgraded to the C-RNTI.
S5, storing the result by using a lookup table
The angles of the base station paths are stored separately, and the angles of the terminal paths and the C-RNTI are in one-to-one correspondence.
S6, receiving signals and estimating the incoming wave direction of the signals
The device receives uplink and downlink signals of a 5G NR system through a transmission array element of the transmission and reflection integrated intelligent reflection surface, and the transmission array element converts electromagnetic signals into electric signals and transmits the electric signals to a control unit. In the control unit, the analog-to-digital converter converts the analog electrical signal into a digital electrical signal, and then sends the digital electrical signal to the FPGA for processing to obtain a binary sequence.
On the one hand, the FPGA carries out path angle estimation on the obtained binary sequence to obtain the incoming wave direction of the signal, and the signal type is judged by comparing the direction of the signal with the direction of the stored base station and terminal. If the direction of the signal is the same as the direction of the base station, the signal is considered to be a downlink signal; otherwise, the signal is considered as an uplink signal.
S7, utilizing the C-RNTI in the lookup table to attempt to demodulate the signal
The signal is a downlink signal, on the other hand, the FPGA tries to demodulate the signal by using the stored C-RNTI, and the demodulation process comprises the steps of OFDM demodulation, time-frequency synchronization, channel estimation, signal detection, de-resource mapping and the like. Since the apparatus stores the C-RNTIs of all terminals within the cell, there will always be one C-RNTI that can successfully demodulate the signal. Because the C-RNTI is in one-to-one correspondence with the terminal direction, the target direction of the downlink signal is obtained.
S8, calculating the reflection coefficient according to the angle of the path obtained in the steps
If the signal is an uplink signal, since there is only one base station in one cell, the target direction of the uplink signal is the direction of the base station. If the signal is a downstream signal, we get the target direction of the downstream signal in step S6.
Zhang and r.zhang in paper "Capacity Characterization for Intelligent Reflecting Surface Aided MIMO Communication" published in IEEE Journal on Selected Areas in Communications propose a method of calculating intelligent reflection coefficients. The method maximizes the channel capacity of the intelligent reflector-assisted communication by jointly optimizing the intelligent reflector reflection coefficient matrix and the transmit covariance matrix.
In the step, rudder vectors are respectively constructed according to the incoming wave direction and the target direction of the signals, and channel coefficients are estimated by using methods such as least square estimation and the like to obtain channel matrixes between the base station and the intelligent reflecting surface and between the user and the intelligent reflecting surface. Finally, the reflection coefficient of the intelligent reflecting surface is calculated by using the method in the paper.
S9, configuring a reflection array element by the intelligent reflection surface according to the reflection coefficient to reflect signals
In this step, the transflective integrated intelligent reflecting surface adjusts the reflection amplitude and phase shift of each reflecting element of the intelligent reflecting surface according to the theoretical reflection coefficient, thereby reflecting the signal.
Referring to fig. 2, fig. 2 is a schematic diagram of an operation scenario of the disclosed device. The intelligent reflective surface assisted communication device operates in a physical cell in which there is a base station and a plurality of terminals, the line of sight path (LOS) between the base station and the terminals being obscured by the building.
Referring to fig. 3, fig. 3 is an implementation of the disclosed apparatus. In this implementation, any element of the transflective integrated smart reflective surface has both a transmissive function and a reflective function.
Referring to fig. 4, fig. 4 is another implementation of the disclosed apparatus. In this implementation, the transflective integrated intelligent reflective surface has a transmissive array element region for receiving signals and the remaining reflective array elements for reflecting signals.
Claims (6)
1. The method for intelligent reflector auxiliary communication is characterized by comprising the following steps of: the method is applied to a cellular mobile communication system and comprises a base station, an intelligent reflecting surface auxiliary communication device and a plurality of mobile terminals, wherein the base station, the intelligent reflecting surface auxiliary communication device and the mobile terminals work in a physical cell, the intelligent reflecting surface auxiliary communication device comprises a transparent and reflective integrated intelligent reflecting surface and a control unit, the transparent and reflective integrated intelligent reflecting surface is used for receiving and reflecting signals, the transparent and reflective integrated intelligent reflecting surface comprises a transmission array element used for receiving the signals and a reflection array element used for reflecting the signals, the array elements in the transparent and reflective integrated intelligent reflecting surface are array elements which are used for realizing transmission or reflection independently, the number of the reflection array elements is far greater than that of the transmission array elements, and the transmission array elements are distributed in the center position of the intelligent reflecting surface in a concentrated mode; or the transmission array element is an integrated array element with transmission and reflection functions at the same time; the control unit is used for processing the signals and calculating the reflection coefficient of the reflection array element of the transparent and reflective integrated intelligent reflection surface;
the method comprises the following steps:
step 1, an intelligent reflecting surface auxiliary communication device receives a system message transmitted by a base station, wherein the system message comprises the bandwidth, the frame structure and the center frequency information of a cell;
step 2, the intelligent reflector auxiliary communication device estimates the angle information of the intelligent reflector path of the base station reaching the intelligent reflector auxiliary communication device by using a main synchronization sequence PSS regulated by a new air interface 5G NR of the 5 th generation mobile communication technology;
step 3, the intelligent reflector auxiliary communication device estimates the angle information of the intelligent reflector path of the mobile terminal reaching the intelligent reflector auxiliary communication device by using a Preamble sequence Preamble specified by 5G NR;
step 4, the intelligent reflection surface auxiliary communication device acquires the cell radio network temporary identifier C-RNTI information of the mobile terminal by utilizing a random access process (defined in 5G NR) initiated by the terminal to the base station;
step 5, storing the result obtained in the step 2-4 by using a lookup table; the angle of the base station path is stored separately, and the angle information of the terminal path and the C-RNTI information of the terminal are arranged in a one-to-one correspondence manner;
step 6, the transmission array element of the transmission and reflection integrated intelligent reflecting surface receives signals, detects the incoming wave direction of the signals, judges the signal type according to the signal direction, judges the downlink signals if the signal type is the same as the direction of the base station, and judges the uplink signals if the signal type is the same as the direction of the base station;
step 7, after the transmission and reflection integrated intelligent reflecting surface judges the received signal as a downlink signal, utilizing the stored C-RNTI to try to demodulate the signal, and if the signal demodulation is successful, taking the angle of the path corresponding to the successfully demodulated C-RNTI as a target direction;
step 8, after the transmission and reflection integrated intelligent reflecting surface judges the received signal as an uplink signal, judging that the uplink signal direction can only be the direction of the base station, calculating channel matrixes between the base station and the transmission and reflection integrated intelligent reflecting surface and between the mobile terminal and the transmission and reflection integrated intelligent reflecting surface, and then calculating the reflection coefficient of the transmission and reflection integrated intelligent reflecting surface;
and 9, the control unit configures the reflection array elements of the transparent and reflective integrated intelligent reflecting surface according to the reflection coefficient to realize signal reflection, so that the deployment complexity of the intelligent reflecting surface auxiliary communication device is effectively reduced, and the convenience and reusability of the intelligent reflecting surface auxiliary communication device are improved.
2. A method of intelligent reflector assisted communication according to claim 1, wherein: the system message described in step 1 includes a synchronization broadcast block SSB, a master system message MIB, and a system message block SIB1.
3. The method for intelligent reflector-assisted communication according to claim 1, wherein the basic method for estimating the base station/terminal path angle in step 2 and step 3 is as follows:
taking a primary synchronization sequence PSS/Preamble sequence Preamble as a local sequence, and performing cross correlation between the local sequence and a received signal of each transmission array element of the transmission and reflection integrated intelligent reflecting surface;
combining peaks of different transmission array elements of the transflective integrated intelligent reflecting surface under the same time delay of the time delay domain into column vectors, calculating covariance matrixes of the column vectors, and decomposing eigenvalues to obtain a signal subspace;
and calculating a space spectrum according to the signal subspace, and searching the peak value of the space spectrum to obtain the path angle.
4. A method for intelligent reflector assisted communication according to claim 3, wherein the process of estimating the base station path angle to the intelligent reflector using the primary synchronization sequence PSS is as follows: firstly, determining the time-frequency resource position of a primary synchronization sequence PSS; then, cross-correlating all possible PSS sequences with the received signal through all frequency grids to obtain a frequency offset value and a physical cell identifier 2 of 5G NR; finally, the cross-correlation result of the obtained frequency offset value and the physical cell identifier 2 of 5G NR is utilized to estimate the angle of the base station reaching the intelligent reflecting surface path through the method of claim 3.
5. A method for intelligent reflector assisted communication according to claim 3, wherein the process of estimating the path angle of the terminal to the intelligent reflector using the Preamble sequence Preamble is as follows: firstly, determining the time-frequency resource position of a Preamble sequence Preamble; then traversing all possible root sequences and all Preamble indexes generated by the root sequences, generating a reference Preamble sequence by using the Preamble indexes, performing cross-correlation on a received signal and the reference Preamble sequence, and further detecting whether the peak value of a correlation peak reaches a certain threshold value; if yes, recording the peak value of the correlation peak, and finally estimating the angle of the terminal reaching the intelligent reflecting surface path by using the method of claim 3; if not, continuing to traverse until the peak value of the detected correlation peak reaches the preset threshold value, and then estimating the path angle.
6. A method of intelligent reflector assisted communication according to claim 2, wherein: the method comprises the following steps of obtaining a terminal C-RNTI by using a random access process initiated by a mobile terminal to a base station:
step 1, an intelligent reflection surface auxiliary communication device receives a random access Preamble, when the Preamble is defined as Msg1, beam scanning is carried out to obtain a beam for transmitting a physical random access channel PRACH, after the reception of the Msg1 is completed, an SSB index is determined according to an index between a random access channel PRACH time-frequency resource and the Preamble sequence Preamble and by referring to a 5G NR uplink synchronization process, and a receiving and transmitting beam pair between a terminal and a base station is determined;
step 2, the intelligent reflection surface auxiliary communication device obtains downlink control information DCI according to the physical downlink control channel PDCCH configuration of the mobile terminal obtained by receiving a system message block SIB1, receives physical downlink shared channel PDSCH transmission scrambled by a random access radio network temporary identifier RA-RNTI, defines the physical downlink shared channel PDSCH transmission as Msg2, obtains an uplink scheduling UL Grant in the Msg2 and a temporary cell radio network temporary identifier TC-RNTI, and defines the physical downlink shared channel PDSCH transmission in 5G NR;
step 3, the intelligent reflection surface auxiliary communication device obtains Physical Uplink Shared Channel (PUSCH) transmission scheduled by the Msg2 according to uplink scheduling (UL Grant) in the Msg2 message, and defines the transmission as Msg3; wherein, the common control channel service data unit CCCH SDU defined in 5G NR in Msg3 is used for verifying whether the common control channel service data unit CCCH SDU is matched with the PDSCH transmission of contention resolution, the message in Msg4 is defined, the PUSCH is scrambled by the TC-RNTI in the Msg2 message, and the time-frequency resource is given by the UL Grant;
and step 4, the intelligent reflector auxiliary communication device receives the contention resolution identification (MAC layer) control unit Contention Resolution IdentityMAC CE in the Msg4, and considers that the random access is successful and upgrades the TC-RNTI into the C-RNTI when the contention resolution identification (MAC layer) control unit Contention Resolution IdentityMAC CE is matched with the CCCH SDU sent by the Msg 3.
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