RIS-assisted millimeter wave multi-user communication method, device, medium and product

Abstract

The present application discloses a RIS-assisted millimeter-wave multi-user communication method, device, medium and product, which relates to the field of wireless transmission technology. Determine the analog beamforming matrix of the base station; obtain the received signal power and beamforming codeword of each user device in each sub-time slot of the time slot of each intelligent reflection surface; construct a preference sequence for the intelligent reflection surface and the user device to obtain an initial matching table and optimize the final matching table, so as to determine the target sequence number of the beamforming codeword of each intelligent reflection surface; estimate the equivalent cascade channel of the user device, calculate the baseband precoding matrix, and generate a radio frequency signal; output the radio frequency signal to the analog beamformer, and feed it to the antenna after phase shifting; the antenna amplifies the radio frequency signal and then incidents it on the intelligent reflection surface, which performs passive beamforming based on the final matching table and reflects electromagnetic waves to the corresponding user device; the user device decodes and recovers the user data stream after receiving. Improves the information transmission rate and communication efficiency.

Description

Technical Field

[0001] The present application relates to the field of wireless transmission technology, and in particular to a RIS-assisted millimeter wave multi-user communication method, device, medium and product. Background Art

[0002] In the intelligent manufacturing scenario, a large number of industrial sensors and intelligent instruments sense production environment information, product status information, equipment operation information, etc., which are uploaded to the control center or cloud for processing by the communication network. The 5th Generation mobile communication system (5G) can better meet the communication needs of intelligent manufacturing scenarios. At present, "5G+Industrial Internet" has been used in quality inspection, remote monitoring, mobile inspection, intelligent logistics, remote control, predictive maintenance, etc. In order to meet the needs of intelligent manufacturing, 5G networks need to use millimeter wave frequency bands to provide higher data rates, lower transmission delays, and more connections. Millimeter waves have the advantages of short wavelengths and good directivity, especially larger available continuous bandwidth. Millimeter wave channels are sparse, that is, they contain few propagation paths; and the propagation loss of non-line-of-sight (NLOS) paths is large, and it is difficult to support high-quality communication links when there is no line-of-sight (LOS) path.

[0003] In smart manufacturing scenarios, there are many users / devices accessing the communication network, collectively referred to as User Equipment (UE) below. Due to the wide distribution of various industrial production and processing equipment in manufacturing scenarios, together with the walls of the workshop, shelves, etc., they have a strong blocking and attenuation effect on the electromagnetic waves in the millimeter wave band, resulting in a lack of LOS path between the base station (BS) or access point (AP) and the UE, and poor channel quality. The recently emerged Reconfigurable Intelligent Surface (RIS) provides a solution to this problem.

[0004] RIS is usually a passive device with a simple structure and low cost. It can be easily deployed on the surface of glass, walls and various large-scale production equipment, and is very suitable for large-scale use in smart manufacturing scenarios. The surface of RIS is composed of a large number of evenly arranged tiny reflection units. Each reflection unit applies a phase shift to the incident electromagnetic wave and reflects it out. The phase shift imposed by the reflection unit can be set independently by the RIS controller. By optimizing the phase shift, the electromagnetic wave energy reflected by the RIS can be concentrated in a specific direction, that is, passive beamforming. When a large number of RIS are deployed in the electromagnetic wave propagation environment, selecting an appropriate RIS for the UE can provide a LOS path for the UE through reflection, and improve the quality of the channel between the BS and the UE through passive beamforming.

[0005] In the millimeter wave channel, the channel gain of the NLOS path is relatively small, and it is difficult to support an effective communication link. In order to provide a high-quality channel, when deploying the RIS, it is usually ensured that there is a LOS path between it and the BS; therefore, a RIS can usually only transmit one data stream, that is, it can only reflect and forward signals for one UE. In a downlink multi-user communication system, it is necessary to select a suitable RIS for each UE to achieve the highest possible communication rate, that is, there is a matching problem between the UE and the RIS. In order for the base station to select the RIS and its beamforming vector, and calculate the baseband beamforming matrix, the UE needs to feedback a large amount of channel state information, resulting in a large feedback overhead and reducing the efficiency of the communication system. Summary of the invention

[0006] The purpose of this application is to provide a RIS-assisted millimeter wave multi-user communication method, device, medium and product, which can improve UE channel quality, reduce mutual interference during multi-user signal transmission, and increase the information transmission rate of UE; reduce UE feedback overhead and improve the efficiency of the communication system.

[0007] To achieve the above objectives, this application provides the following solutions.

[0008] In a first aspect, the present application provides a RIS-assisted millimeter wave multi-user communication method, wherein the RIS-assisted millimeter wave multi-user communication method is implemented using a millimeter wave multi-user communication system, wherein the millimeter wave multi-user communication system comprises: a base station, a plurality of intelligent reflection surfaces, and a plurality of user devices; the number of the intelligent reflection surfaces and the number of the user devices are equal; the positions of the base station and each of the intelligent reflection surfaces are fixed;

[0009] The RIS-assisted millimeter wave multi-user communication method comprises:

[0010] Determine a simulated beamforming matrix of the base station; the simulated beamforming matrix includes: simulated beamforming vectors of the antenna array of the base station pointing to each intelligent reflection surface;

[0011] The base station sends a training signal to the corresponding smart reflection surface based on each simulated beamforming vector in the time slot of each smart reflection surface; obtains the received signal power of each user equipment in multiple sub-time slots contained in the time slot of each smart reflection surface and the sequence number of the corresponding beamforming codeword, sorts the received signal power in all sub-time slots of each smart reflection surface in order from large to small, and sorts the front beam of each smart reflection surface. L The received signal power and the corresponding beamforming codeword number are fed back to the base station. L is a preset constant;

[0012] Based on the received signal power of each user equipment in multiple sub-time slots included in the time slot of each smart reflection surface, the base station constructs a preference sequence for each smart reflection surface and each user equipment; the preference sequence includes: a preference sequence of the smart reflection surface and a preference sequence of the user equipment; the preference sequence of the smart reflection surface includes: a plurality of first preference values, the first preference value is a preference value of the smart reflection surface to the user equipment; the preference sequence of the user equipment includes: a plurality of second preference values, the second preference value is a preference value of the user equipment to the smart reflection surface;

[0013] The base station determines the initial pairing of the smart reflective surface and the user equipment according to the preference sequence to obtain an initial matching table;

[0014] Optimizing the initial matching table based on an approximate signal to interference noise ratio of each user equipment to obtain a final matching table, and determining a target sequence number of a beamforming codeword of each smart reflection surface based on the final matching table;

[0015] The analog beamformer of the base station is set to an analog beamforming matrix, and the target beamforming vector of each smart reflection surface is set to a beamforming codeword corresponding to the target sequence number;

[0016] Each user equipment sends a pilot sequence in turn, and the base station estimates the equivalent cascade channel of each user equipment; based on the equivalent cascade channel of each user equipment and the analog beamformer, the base station calculates the baseband precoding matrix; based on the baseband precoding matrix and the user data stream of each user equipment, a digital baseband signal is generated; the digital-to-analog conversion module converts each digital baseband signal into an analog baseband signal; each radio frequency link converts the analog baseband signal into a radio frequency signal;

[0017] The RF signal generated by each RF link is output to the corresponding analog beamformer and fed to each antenna after phase shifting;

[0018] The antenna amplifies the RF signal and radiates it in the form of radio electromagnetic waves; the electromagnetic waves are incident on the smart reflective surface, which uses beamforming codewords to perform passive beamforming based on the final matching table to reflect the incident electromagnetic waves toward the corresponding user device; the user device receives the radio electromagnetic wave signal and decodes it to restore the user data stream.

[0019] Optionally, determining a simulated beamforming matrix of a base station includes:

[0020] Obtaining a departure angle of a direct path between a base station and each smart reflector and the number of antennas in the antenna array;

[0021] Based on the number of antennas and the departure angles, a simulated beamforming vector of the antenna array of the base station pointing to the corresponding smart reflection surface is determined.

[0022] Optionally, the calculation formula of the preference value of the user device of the intelligent reflection surface includes:

[0023] ;

[0024] in, Indicates An intelligent reflection faces the The preference value of each user device; Indicates User equipment in The first intelligent reflective surface The received signal power in a sub-time slot; Indicates the number of user devices;

[0025] The calculation formula of the preference value of the user equipment for the smart reflective surface includes:

[0026] ;

[0027] in, Indicates User equipment for the The preference value of a smart reflective surface; Indicates the number of smart reflective surfaces.

[0028] Optionally, the base station determines an initial pairing of the smart reflective surface and the user equipment according to the preference sequence, and obtains an initial matching table, including:

[0029] Each intelligent reflective surface respectively proposes a matching invitation in the first round to the user equipment with the largest first preference value;

[0030] Each user device uses the intelligent reflective surface with the largest second preference value among the intelligent reflective surfaces that propose the matching invitation in the first round as a candidate intelligent reflective surface in the first round, and initiates a rejection in the first round for other intelligent reflective surfaces, thereby obtaining an initial matching result;

[0031] On the basis of the initial matching result, the smart reflecting surfaces and the user equipment are paired in multiple rounds in descending order of the first preference values, based on the first preference values ​​corresponding to the smart reflecting surfaces and the second preference values ​​corresponding to the user equipment, to obtain an initial matching table; wherein the matching process in any current round includes:

[0032] Determine the candidate smart reflective surfaces in the previous round as the complex matching smart reflective surfaces in the current round, and determine the rejected smart reflective surfaces in the previous round as the initial matching smart reflective surfaces in the current round;

[0033] The multiple matching intelligent reflection face in each current round sends a matching invitation in the current round to the user equipment that proposed the matching invitation in the previous round, and the primary matching intelligent reflection face in each current round sends a matching invitation in the current round to the user equipment whose first preference value is one position after the first preference value of the user equipment that proposed the matching invitation in the previous round;

[0034] Each user equipment uses the intelligent reflective surface with the largest second preference value among the intelligent reflective surfaces that propose a matching invitation in the current round as a candidate intelligent reflective surface in the current round, and initiates a rejection in the current round for other intelligent reflective surfaces;

[0035] Update the current round to the next round, and return to "determine the candidate smart reflective surface in the previous round as the complex matching smart reflective surface in the current round, and determine the rejected smart reflective surface in the previous round as the initial matching smart reflective surface in the current round" until each user device receives a matching invitation and obtains an initial matching table.

[0036] Optionally, optimizing the initial matching table based on the approximate signal to interference plus noise ratio of each user equipment to obtain a final matching table includes:

[0037] Determine, based on the initial matching table, a received signal to interference plus noise ratio between each smart reflecting surface in the initial matching table and the corresponding user equipment, and determine the received signal to interference plus noise ratio between each smart reflecting surface in the initial matching table and the corresponding user equipment as an initial received signal to interference plus noise ratio;

[0038] Determine respectively the received signal-to-interference-plus-noise ratio between each smart reflective surface and each user equipment in the initial matching table as the received signal-to-interference-plus-noise ratio to be exchanged;

[0039] According to the sequence of setting the smart reflective surfaces, based on the initial received signal to interference plus noise ratio corresponding to each smart reflective surface and each received signal to interference plus noise ratio to be exchanged, the target user equipment corresponding to each smart reflective surface is determined in sequence;

[0040] The final matching table is determined according to the target user equipment corresponding to each intelligent reflection surface.

[0041] Optionally, a calculation formula for an equivalent cascade channel of the user equipment includes:

[0042] ;

[0043] in, Indicates Equivalent cascaded channels of user equipment; It represents the first estimated value on the RF link corresponding to the first smart reflector. The equivalent channel value of each user equipment; It represents the estimated first value on the RF link corresponding to the second smart reflector. The equivalent channel value of each user equipment; Indicated in The first estimated value on the RF link corresponding to the smart reflector The equivalent channel value of each user equipment.

[0044] Optionally, a calculation formula for the baseband precoding matrix includes:

[0045] ;

[0046] ;

[0047] in, represents the baseband precoding matrix; represents an equivalent base station-intelligent reflection surface-user equipment cascade channel matrix; express The transpose of represents the analog beamforming matrix; represents the F-norm; Indicates the equivalent cascade channel of the first user equipment; represents the equivalent cascade channel of the second user equipment; Indicates The equivalent cascaded channels of the user equipment.

[0048] In a second aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the above-described RIS-assisted millimeter wave multi-user communication methods.

[0049] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-mentioned RIS-assisted millimeter wave multi-user communication methods.

[0050] In a fourth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned RIS-assisted millimeter wave multi-user communication methods.

[0051] According to the specific embodiments provided by the present application, the present application discloses the following technical effects: The present application discloses a RIS-assisted millimeter wave multi-user communication method, device, medium and product. In multiple RIS-assisted millimeter wave multi-user communication scenarios, the UE receives the training signal formed and reflected by the RIS beam, and only selects the largest several receiving power values, and feeds these receiving power values ​​and the corresponding beamforming codeword sequence numbers back to the base station. The base station uses the feedback information to allocate a suitable RIS to each UE, reduce mutual interference in the multi-user signal transmission process, and improve the information transmission rate of the UE; at the same time, the amount of feedback information is reduced, and the communication efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 A schematic flow chart of a RIS-assisted millimeter wave multi-user communication method provided in one embodiment of the present application.

[0054] Figure 2 The present invention is a flow chart of a transmission method for a RIS-assisted millimeter wave multi-user communication system.

[0055] Figure 3 This is the structural diagram of the millimeter wave multi-user communication system.

[0056] Figure 4 This is a simplified diagram of the base station processing module.

[0057] Figure 5 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0059] The purpose of this application is to provide a RIS-assisted millimeter wave multi-user communication method, device, medium and product, which aims to improve UE channel quality, reduce mutual interference during multi-user signal transmission, and increase the information transmission rate of UE; reduce UE feedback overhead and improve the efficiency of the communication system.

[0060] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0061] In an exemplary embodiment, Figure 1 and Figure 2 As shown, the RIS-assisted millimeter wave multi-user communication method in this embodiment utilizes Figure 3 and Figure 4 The millimeter wave multi-user communication system shown is implemented, and the millimeter wave multi-user communication system includes: a base station, multiple smart reflection surfaces and multiple user equipment; the number of smart reflection surfaces and user equipment is equal; the positions of the base station and each smart reflection surface are fixed.

[0062] Specifically, in a millimeter wave multi-user communication system, a base station sends signals to all UEs. The RIS is usually installed at a higher place and fixed in position, so there is a direct path between the base station and the RIS. , and . Due to obstacles, there is no direct path between the base station and the UE. To improve the quality of the communication link, the signal transmitted by the base station is reflected by the RIS and then reaches the UE. The RIS uses a beamforming vector to concentrate the energy of the reflected signal in the direction of a certain UE. In the above-mentioned communication system with multiple RIS, a suitable RIS should be selected for each UE, that is, one UE is matched with one RIS; at the same time, an optimal beamforming vector, that is, a target beamforming vector, is selected for the RIS to enable the UE to achieve the highest possible communication rate and reduce mutual interference during multi-user signal transmission.

[0063] The base station uses hybrid beamforming technology. Beamforming consists of two parts: analog beamforming and baseband precoding. The base station processing module includes:

[0064] (1) Antenna array: The uniformly distributed antennas form a uniform linear array.

[0065] (2) Analog beamformer: Each RF link is connected to an analog beamformer. A phase shifter.

[0066] (3) Radio Frequency (RF) link: realizes the conversion between analog baseband signals and RF signals.

[0067] (4) Digital-to-analog conversion module: converts digital baseband signals into analog baseband signals.

[0068] (5) Baseband precoding module: pre-processes multi-user signals to suppress multi-user interference generated during transmission.

[0069] (6) Channel estimation module: Estimate the BS-RIS-UE cascade channel for each UE.

[0070] The RIS-assisted millimeter wave multi-user communication method includes steps 1 to 9.

[0071] Step 1: Determine the analog beamforming matrix of the base station.

[0072] The simulated beamforming matrix includes: simulated beamforming vectors of the antenna array of the base station pointing to each intelligent reflection surface.

[0073] As an optional implementation, step 1 includes steps 11 and 12.

[0074] Step 11: Obtain the departure angle of the direct path between the base station and each smart reflector and the number of antennas in the antenna array.

[0075] Step 12: Based on the number of antennas and each departure angle, determine the simulated beamforming vector of the base station's antenna array pointing to the corresponding smart reflection surface.

[0076] Specifically, the RIS is installed at a higher place and has a fixed position, and there is a LOS path between the BS and the RIS. The departure angle of the LOS path between two smart reflectors (RIS r) can be obtained by measuring = ... for:

[0077] .

[0078] in, Indicates the number of antennas in the BS antenna array; Represents the distance between two adjacent antennas; represents the carrier wavelength, Represents a transpose operation. The simulated beamforming vectors of the RIS constitute the simulated beamforming matrix of the base station :

[0079] .

[0080] in, represents the simulated beamforming vector of the BS antenna array pointing to the first smart reflector (RIS 1); Figure 2. Simulated beamforming vector representing the BS antenna array pointing toward the second smart reflector (RIS 2).

[0081] Step 2: In the time slot of each smart reflection surface, the base station sends a training signal to the corresponding smart reflection surface based on each simulated beamforming vector; obtain the received signal power of each user equipment in multiple sub-time slots contained in the time slot of each smart reflection surface and the sequence number of the corresponding beamforming codeword, sort the received signal power in all sub-time slots of each smart reflection surface in order from large to small, and sort the front beam of each smart reflection surface. L The received signal power and the corresponding beamforming codeword number are fed back to the base station. L is a preset constant.

[0082] Specifically, first, the base station uses the analog beamforming vector in the time slot of RIS r The training signal is transmitted to RIS r. At this time, the BS turns off other RIS through the RIS controller, that is, does not reflect the signal. The beamforming codebook set of RIS r is , Indicates the first beamforming vector / codeword in sub-time slots, RIS r controller in In each sub-time slot, the beamforming vectors of RIS r are set to At this time Each user equipment (UE k) will The received signal power in a sub-time slot The training process lasts until The RIS training is completed.

[0083] Table 1 Received power table

[0084]

[0085] in, represents the received signal power of UE k in the first sub-time slot of RIS 1; represents the received signal power of UE k in the first sub-time slot of RIS 2; represents the received signal power of UE k in the first sub-time slot of RISPR; represents the received signal power of UE k in the second sub-time slot of RIS 1; represents the received signal power of UE k in the second sub-time slot of RIS 2; represents the received signal power of UE k in the second sub-time slot of RIS R; Indicates the number of UE k in RIS 1 The received signal power in a sub-time slot; Indicates that UE k is in the first The received signal power in a sub-time slot; Indicates that UE k is in the first The received signal power in a sub-time slot.

[0086] Secondly, UE k feeds back its received signal power and the corresponding beamforming codeword, For RIS r, UE k selects the maximum received signal power from the N sub-time slots. L The received signal power and the corresponding beamforming codeword sequence number are fed back to the base station. , that is, partial feedback, can significantly reduce the amount of information fed back by the UE. Assuming that millimeter wave and sub-6 GHz are networked together, sub-6 GHz is used for control channels, and millimeter wave is used for service channels, the UE will feed back part of the received signal power and the corresponding beamforming codeword sequence number to the base station through the established control channel.

[0087] Step 3: Based on the received signal power of each user equipment in a plurality of sub-time slots included in the time slot of each smart reflection surface, the base station constructs a preference sequence for each smart reflection surface and each user equipment.

[0088] Among them, the preference sequence includes: a preference sequence of the intelligent reflecting surface and a preference sequence of the user equipment; the preference sequence of the intelligent reflecting surface includes: multiple first preference values, the first preference value is the preference value of the intelligent reflecting surface to the user equipment; the preference sequence of the user equipment includes: multiple second preference values, the second preference value is the preference value of the user equipment to the intelligent reflecting surface.

[0089] As an optional implementation, the calculation formula of the preference value of the intelligent reflection face user equipment includes:

[0090] .

[0091] in, Indicates An intelligent reflection faces the The preference value of each user device; Indicates User equipment in The first intelligent reflective surface The received signal power in a sub-time slot; Indicates the number of user devices.

[0092] The calculation formula of the preference value of the user equipment for the smart reflective surface includes:

[0093] .

[0094] in, Indicates User equipment for the The preference value of a smart reflective surface; Indicates the number of smart reflective surfaces.

[0095] Specifically, the preference sequence of RIS r is defined as the sequence of all UEs according to The sequence formed by sorting the UE numbers from large to small. Then the preference sequence of RIS r is A permutation of ,and .

[0096] The preference sequence of UE k is defined as all RISs according to The sequence formed by sorting the RIS numbers from large to small. Then the preference sequence of UE k is A permutation of ,and .

[0097] Step 4: The base station determines the initial pairing of the smart reflective surface and the user equipment according to the preference sequence, and obtains an initial matching table.

[0098] As an optional implementation, step 4 includes steps 41 to 43.

[0099] Step 41: Each intelligent reflective surface respectively submits a matching invitation in the first round to the user equipment with the largest first preference value.

[0100] Step 42: Each user device takes the intelligent reflective surface with the largest second preference value among the intelligent reflective surfaces that have issued the matching invitation in the first round as a candidate intelligent reflective surface in the first round, and initiates a rejection in the first round for other intelligent reflective surfaces, thereby obtaining an initial matching result.

[0101] Step 43: Based on the initial matching result, the smart reflective surfaces and the user devices are paired in multiple rounds in descending order of the first preference values, based on the first preference values ​​corresponding to the smart reflective surfaces and the second preference values ​​corresponding to the user devices, to obtain an initial matching table; wherein the matching process in any current round includes:

[0102] Step 431: determine the candidate smart reflective surfaces in the previous round as the complex matching smart reflective surfaces in the current round, and determine the rejected smart reflective surfaces in the previous round as the initial matching smart reflective surfaces in the current round.

[0103] Step 432: The complex matching intelligent reflection surface in each current round sends a matching invitation in the current round to the user device that submitted the matching invitation in the previous round, and the initial matching intelligent reflection surface in each current round submits a matching invitation in the current round to the user device whose first preference value is one position after the first preference value of the user device that submitted the matching invitation in the previous round.

[0104] Step 433: Each user device takes the smart reflective surface with the largest second preference value among the smart reflective surfaces that have issued the matching invitation in the current round as a candidate smart reflective surface in the current round, and initiates a rejection in the current round for other smart reflective surfaces.

[0105] Step 434: Update the current round to the next round, and return to step 431 until each user device receives a matching invitation and obtains an initial matching table.

[0106] Specifically, step 4 specifically includes the following steps.

[0107] 4-1. Each RIS sends a matching invitation to the UE with the largest first preference value.

[0108] 4-2. Each UE selects a RIS with the largest second preference value in its preference sequence from the RISs that send invitations to it to add it to its candidate set, that is, accepts its invitation and rejects other RISs.

[0109] 4-3. The rejected RIS sends an invitation to the next UE in its preference order; the RIS that is not rejected sends an invitation again to the UE that accepts its invitation.

[0110] 4-4. Return to step 4-2 until each UE receives only one invitation.

[0111] 4-5. Each UE accepts the invitation and matches with the RIS that sent the invitation. The resulting pairing result is recorded in the initial matching table, where the RIS are arranged in ascending order according to the serial number. For example, a matching result is shown below.

[0112] Table 2 Matching results table

[0113]

[0114] RIS r With UE k Pairing, that is, UE k Choose RIS r, by RIS r For UE k Reflected signal, RIS r The number of the beamforming codeword used for:

[0115] .

[0116] Step 5: Optimize the initial matching table based on the approximate signal to noise ratio of each user equipment to obtain a final matching table, and determine the target sequence number of the beamforming codeword of each smart reflection surface based on the final matching table.

[0117] As an optional implementation, step 5 includes steps 51 to 54.

[0118] Step 51: Determine the received signal to interference plus noise ratio between each smart reflecting surface in the initial matching table and the corresponding user equipment based on the initial matching table, and determine the received signal to interference plus noise ratio between each smart reflecting surface in the initial matching table and the corresponding user equipment as the initial received signal to interference plus noise ratio.

[0119] Step 52: Determine the received signal-to-interference-plus-noise ratios between each smart reflection surface and each user equipment in the initial matching table as the received signal-to-interference-plus-noise ratios to be exchanged.

[0120] Step 53: according to the sequence of setting the smart reflective surfaces, based on the initial received signal to interference plus noise ratio corresponding to each smart reflective surface and each received signal to interference plus noise ratio to be exchanged, determine the target user equipment corresponding to each smart reflective surface in turn.

[0121] Step 54: Determine a final matching table according to the target user equipment corresponding to each smart reflective surface.

[0122] Specifically, step 5 specifically includes the following steps.

[0123] 5-1. The BS constructs an approximate received signal power table of UE k based on the information fed back by UE k. The approximate received signal power table is shown in Table 3.

[0124] Table 3 Approximate received signal power table

[0125]

[0126] In Table 3, if the position has the received signal power fed back by the UE, the power value of the received signal power is written into the corresponding position, such as UE k Feedback of the received signal power value when RIS 1 uses beamforming codeword 2 is written into the table r =1, n=2; if there is no received signal power value fed back by the UE at a certain position in the table, it is approximated by 0. Due to the sparsity of the millimeter wave channel, the channel gain in the direction corresponding to most codewords is very weak, and the UE's received power is very small. The larger L is, the smaller the error generated by the approximation.

[0127] 5-2. Optimize the initial matching table. The initial matching is shown in Table 2. A RIS-UE matching table in Table 2 is used express, , ,UE For RIS The received signal-to-interference-noise ratio for:

[0128] .

[0129] in, Indicates a match Medium RIS The number of the beamforming codeword used, ; represents the noise power, which is a constant; Indicates that RIS r matches Using beamforming codewords When The power of the received RIS r reflected signal; Indicates UE The interference power received. The base station searches for UE The approximate received signal power table can be used to obtain the power values ​​in the above formula. For the matching results in the initial matching table, the approximate received signal to noise ratio of each UE can be calculated according to the above method. The transmission rate for: .

[0130] 5-3. Optimize matching by swapping. Let r = 1, the corresponding matching is ; Search the initial match table for another match that satisfies the following formula , :

[0131] .

[0132] in, Indicates UE For the received signal-to-interference-and-noise ratio of RIS r; Indicates UE k for RIS The received signal-to-interference-noise ratio; represents the received signal-to-interference-and-noise ratio of UE k to RIS r.

[0133] If there is a match that satisfies the above conditions , then and If the user is exchanged, the initial matching table is modified; otherwise, the initial matching table is not changed. The modified matching table is as follows.

[0134] Table 4 Modified matching table

[0135]

[0136] 5-4. Let r = r + 1, and return to 5-3 until r = R. When the initial matching table is modified to the end of the iteration, it becomes the final matching table. For example, the final matching table is shown in Table 5.

[0137] Table 5 Final matching table

[0138]

[0139] For a match in the final RIS-UE match table , the sequence number of the beamforming codeword used by RIS r is the target sequence number for:

[0140] .

[0141] Step 6: The analog beamformer of the base station is set to an analog beamforming matrix, and the target beamforming vector of each smart reflection surface is set to a beamforming codeword corresponding to the target sequence number.

[0142] Specifically, the base station sets the analog beamformer to ; Set the beamforming vector of RIS r to , .

[0143] Step 7: Each user equipment sends a pilot sequence in turn, and the base station estimates the equivalent cascade channel of each user equipment; based on the equivalent cascade channel of each user equipment and the analog beamformer, the base station calculates the baseband precoding matrix; based on the baseband precoding matrix and the user data stream of each user equipment, a digital baseband signal is generated; the digital-to-analog conversion module converts each digital baseband signal into an analog baseband signal; and each RF link converts the analog baseband signal into a RF signal.

[0144] As an optional implementation manner, a calculation formula for an equivalent cascade channel of a user equipment includes:

[0145] .

[0146] in, Indicates Equivalent cascaded channels of user equipment; It represents the first estimated value on the RF link corresponding to the first smart reflector. The equivalent channel value of each user equipment; It represents the estimated first value on the RF link corresponding to the second smart reflector. The equivalent channel value of each user equipment; Indicated in The first estimated value on the RF link corresponding to the smart reflector The equivalent channel value of each user equipment.

[0147] As an optional implementation manner, a calculation formula for the baseband precoding matrix includes:

[0148] .

[0149] .

[0150] in, represents the baseband precoding matrix; represents an equivalent base station-intelligent reflection surface-user equipment cascade channel matrix; express The transpose of represents the analog beamforming matrix; represents the F-norm; Indicates the equivalent cascade channel of the first user equipment; represents the equivalent cascade channel of the second user equipment; Indicates The equivalent cascaded channels of the user equipment.

[0151] Step 8: The RF signal generated by each RF link is output to the corresponding analog beamformer and fed to each antenna after phase shifting.

[0152] Step 9: The antenna amplifies the RF signal and radiates it in the form of radio electromagnetic waves; the electromagnetic waves are incident on the smart reflective surface, which uses beamforming codewords to perform passive beamforming based on the final matching table to reflect the incident electromagnetic waves to the corresponding user equipment; the user equipment receives the radio electromagnetic wave signal and decodes it to restore the user data stream.

[0153] Specifically, the UE receives a radio signal, and obtains a corresponding user data stream through RF link, analog-to-digital conversion, demodulation and other processing.

[0154] In an exemplary embodiment, a computer device is provided, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a RIS-assisted millimeter wave multi-user communication method.

[0155] In an exemplary embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, a RIS-assisted millimeter wave multi-user communication method is implemented.

[0156] In an exemplary embodiment, a computer program product is provided, including a computer program, which implements a RIS-assisted millimeter wave multi-user communication method when executed by a processor.

[0157] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 5 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a RIS-assisted millimeter wave multi-user communication method is implemented.

[0158] Those skilled in the art will understand that Figure 5 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0159] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0160] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0161] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0162] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0163] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A RIS-assisted millimeter wave multi-user communication method, wherein the RIS-assisted millimeter wave multi-user communication method is implemented using a millimeter wave multi-user communication system, characterized in that: The millimeter wave multi-user communication system comprises: a base station, a plurality of intelligent reflection surfaces and a plurality of user equipments; the number of the intelligent reflection surfaces and the number of the user equipments are equal; the positions of the base station and each of the intelligent reflection surfaces are fixed; The RIS-assisted millimeter wave multi-user communication method comprises: Determine a simulated beamforming matrix of the base station; the simulated beamforming matrix includes: simulated beamforming vectors of the antenna array of the base station pointing to each intelligent reflection surface; The base station sends a training signal to the corresponding smart reflection surface based on each simulated beamforming vector in the time slot of each smart reflection surface; obtains the received signal power of each user equipment in multiple sub-time slots contained in the time slot of each smart reflection surface and the sequence number of the corresponding beamforming codeword, sorts the received signal power in all sub-time slots of each smart reflection surface in order from large to small, and sorts the front beam of each smart reflection surface. L The received signal power and the corresponding beamforming codeword number are fed back to the base station. L is a preset constant; Based on the received signal power of each user equipment in multiple sub-time slots included in the time slot of each smart reflection surface, the base station constructs a preference sequence for each smart reflection surface and each user equipment; the preference sequence includes: a preference sequence of the smart reflection surface and a preference sequence of the user equipment; the preference sequence of the smart reflection surface includes: a plurality of first preference values, the first preference value is a preference value of the smart reflection surface to the user equipment; the preference sequence of the user equipment includes: a plurality of second preference values, the second preference value is a preference value of the user equipment to the smart reflection surface; The base station determines the initial pairing of the smart reflective surface and the user equipment according to the preference sequence to obtain an initial matching table; Optimizing the initial matching table based on an approximate signal to interference noise ratio of each user equipment to obtain a final matching table, and determining a target sequence number of a beamforming codeword of each smart reflection surface based on the final matching table; The analog beamformer of the base station is set to an analog beamforming matrix, and the target beamforming vector of each smart reflection surface is set to a beamforming codeword corresponding to the target sequence number; Each user equipment sends a pilot sequence in turn, and the base station estimates the equivalent cascade channel of each user equipment; based on the equivalent cascade channel of each user equipment and the analog beamformer, the base station calculates the baseband precoding matrix; based on the baseband precoding matrix and the user data stream of each user equipment, a digital baseband signal is generated; the digital-to-analog conversion module converts each digital baseband signal into an analog baseband signal; each radio frequency link converts the analog baseband signal into a radio frequency signal; The RF signal generated by each RF link is output to the corresponding analog beamformer and fed to each antenna after phase shifting; The antenna amplifies the RF signal and radiates it in the form of radio electromagnetic waves. The electromagnetic waves are incident on the smart reflective surface, which uses the beamforming codewords based on the final matching table to perform passive beamforming and reflect the incident electromagnetic waves to the corresponding user equipment. The user equipment receives the radio electromagnetic wave signal and decodes it to restore the user data stream. The calculation formula of the preference value of the user device in the intelligent reflection face includes: ； in, Indicates An intelligent reflection faces the The preference value of each user device; Indicates User equipment in The first intelligent reflective surface The received signal power in a sub-time slot; Indicates the number of user devices; The calculation formula of the preference value of the user equipment for the smart reflective surface includes: ； in, Indicates User equipment for the The preference value of a smart reflective surface; Indicates the number of smart reflective surfaces; The base station determines the initial pairing of the smart reflective surface and the user equipment according to the preference sequence, and obtains an initial matching table, including: Each intelligent reflective surface respectively proposes a matching invitation in the first round to the user equipment with the largest first preference value; Each user device uses the intelligent reflective surface with the largest second preference value among the intelligent reflective surfaces that propose the matching invitation in the first round as a candidate intelligent reflective surface in the first round, and initiates a rejection in the first round for other intelligent reflective surfaces, thereby obtaining an initial matching result; On the basis of the initial matching result, the smart reflecting surfaces and the user equipment are paired in multiple rounds in descending order of the first preference values, based on the first preference values ​​corresponding to the smart reflecting surfaces and the second preference values ​​corresponding to the user equipment, to obtain an initial matching table; wherein the matching process in any current round includes: Determine the candidate smart reflective surfaces in the previous round as the complex matching smart reflective surfaces in the current round, and determine the rejected smart reflective surfaces in the previous round as the initial matching smart reflective surfaces in the current round; The multiple matching intelligent reflection face in each current round sends a matching invitation in the current round to the user equipment that proposed the matching invitation in the previous round, and the primary matching intelligent reflection face in each current round sends a matching invitation in the current round to the user equipment whose first preference value is one position after the first preference value of the user equipment that proposed the matching invitation in the previous round; Each user equipment uses the intelligent reflective surface with the largest second preference value among the intelligent reflective surfaces that propose a matching invitation in the current round as a candidate intelligent reflective surface in the current round, and initiates a rejection in the current round for other intelligent reflective surfaces; Update the current round to the next round, and return to "determine the candidate smart reflective surface in the previous round as the complex matching smart reflective surface in the current round, and determine the rejected smart reflective surface in the previous round as the initial matching smart reflective surface in the current round", until each user device receives a matching invitation and obtains an initial matching table; Optimizing the initial matching table based on the approximate signal to interference noise ratio of each user equipment to obtain a final matching table includes: Determine, based on the initial matching table, a received signal to interference plus noise ratio between each smart reflecting surface in the initial matching table and the corresponding user equipment, and determine the received signal to interference plus noise ratio between each smart reflecting surface in the initial matching table and the corresponding user equipment as an initial received signal to interference plus noise ratio; Determine respectively the received signal-to-interference-plus-noise ratio between each smart reflective surface and each user equipment in the initial matching table as the received signal-to-interference-plus-noise ratio to be exchanged; According to the sequence of setting the smart reflective surfaces, based on the initial received signal to interference plus noise ratio corresponding to each smart reflective surface and each received signal to interference plus noise ratio to be exchanged, the target user equipment corresponding to each smart reflective surface is determined in sequence; The final matching table is determined according to the target user equipment corresponding to each intelligent reflection surface.

2. The RIS-assisted millimeter wave multi-user communication method according to claim 1, characterized in that: Determine the analog beamforming matrix of the base station, including: Obtaining a departure angle of a direct path between a base station and each smart reflector and the number of antennas in the antenna array; Based on the number of antennas and the departure angles, a simulated beamforming vector of the antenna array of the base station pointing to the corresponding smart reflection surface is determined.

3. The RIS-assisted millimeter wave multi-user communication method according to claim 1, characterized in that: The calculation formula of the equivalent cascade channel of the user equipment includes: ； in, Indicates Equivalent cascaded channels of user equipment; It represents the first estimated value on the RF link corresponding to the first smart reflector. Equivalent channel value of each user equipment; It represents the estimated first value on the RF link corresponding to the second smart reflector. Equivalent channel value of each user equipment; Indicated in The first estimated value on the RF link corresponding to the smart reflector The equivalent channel value of each user equipment.

4. The RIS-assisted millimeter wave multi-user communication method according to claim 3, characterized in that: The calculation formula of the baseband precoding matrix includes: ； ； in, represents the baseband precoding matrix; represents an equivalent base station-intelligent reflection surface-user equipment cascade channel matrix; express The transpose of represents the analog beamforming matrix; represents the F-norm; Indicates the equivalent cascade channel of the first user equipment; represents the equivalent cascade channel of the second user equipment; Indicates The equivalent cascaded channels of the user equipment.

5. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the RIS-assisted millimeter wave multi-user communication method according to any one of claims 1 to 4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the RIS-assisted millimeter wave multi-user communication method described in any one of claims 1 to 4 is implemented.

7. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the RIS-assisted millimeter wave multi-user communication method described in any one of claims 1 to 4 is implemented.

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