A downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system

Abstract

The present application relates to a kind of downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system, belong to wireless communication field.The method includes: constructing integrated system signal transmission model;Establish system rate and maximization problem, optimization variable is the NOLM power allocation of two users by base station and relay and the energy splitting coefficient of STAR-RIS;Using the idea of two-stage relay system flow balance, the relationship between the four power values is determined;Construct double-layer iteration joint optimization method, obtain the optimal solution of system.When system power or STAR-RIS element number is limited, relay can be activated to obtain better performance, otherwise relay can be closed to save energy.The present application provides a new method for RIS and relay combination technology, and provides a flexible and efficient solution for coverage enhancement in future wireless networks.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication, and particularly relates to a downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system. Background Technology

[0002] With the rapid increase in demand for communication bandwidth and speed from new mobile services, the evolution towards higher frequency bands such as millimeter waves and terahertz has become an inevitable trend in the evolution of post-5G and future 6G mobile communication networks. However, the most obvious characteristics of high-frequency signals are high path loss, small cell radius, and significant susceptibility to obstruction, rain, snow, and environmental absorption. Reconfigurable Intelligent Surfaces (RIS) offer an effective solution to this problem by dynamically controlling each electromagnetic unit, thereby achieving programmable and proactive intelligent regulation of spatial electromagnetic waves to form an electromagnetic field distribution with controllable amplitude, phase, and other parameters. Therefore, RIS has great potential for enhancing coverage and capacity in future wireless networks, providing virtual line-of-sight links, eliminating local coverage holes, serving cell edge users, and ultimately realizing an intelligent and reconfigurable wireless environment.

[0003] Traditional single-reflection or single-transmission RIS (Radio Resonance Surface) systems require the user to be located on the same side of the RIS, achieving only half-space coverage and severely limiting the flexibility of RIS deployment. Building on this limitation, the concept of an omnidirectional intelligent metasurface (Simultaneously Transmitting and Reflecting Reconfigurable Intelligent Surface, STAR-RIS) was proposed. Its unique feature is that it can simultaneously transmit and reflect incident signals. Therefore, compared to single-reflection or single-transmission RIS, STAR-RIS can achieve full-space coverage.

[0004] In previous generations of wireless communication, active cooperative repeaters played a crucial role in providing reliable and energy-efficient communication. However, repeaters suffer from drawbacks such as high signal processing complexity, increased noise interference, and high implementation costs. Simple, low-cost, and passive relay systems (RIS) can mitigate these disadvantages. Many studies currently view RIS and repeaters as competing technologies, but some research has shown that repeaters can be considered additional performance enhancement components for RIS-assisted transmission scenarios, especially under conditions of rapid channel degradation.

[0005] Non-Orthogonal Multiple Access (NOMA) offers significant advantages in spectral efficiency, low transmission latency, and massive connectivity, making it a promising candidate for future mobile communications. Unlike traditional Orthogonal Multiple Access (OMA), NOMA allows multiple users to transmit simultaneously using the same time and frequency resources, significantly improving spectral efficiency and system capacity. However, NOMA introduces multi-user interference, posing several technical challenges for practical applications. Proper power allocation can effectively suppress multi-user interference, improve the signal-to-noise ratio at the receiver, and ensure data transmission for users at the cell edge.

[0006] Both RIS and NOMA technologies are key technologies in future wireless communications, and their combination with existing mature relay technologies can play a greater role. In recent years, hybrid RIS and relay schemes have received less attention in multi-user systems and have not been linked to relays. Given the limitations of existing research, this invention proposes a novel dual-user hybrid network. To reduce the significant channel estimation overhead, STAR-RIS is integrated with half-duplex (HD) decode-and-forward (DF) relay and combined with NOMA technology. This invention utilizes the idea of ​​two-stage relay system traffic balancing and proposes a two-layer iterative algorithm to maximize the sum of achievable rates for the two users in the system by jointly optimizing the NOMA power allocation at the base station and relay, as well as the energy splitting coefficient of STAR-RIS. The proposed scheme provides a flexible and efficient solution for coverage enhancement in future wireless networks. Summary of the Invention

[0007] To address the limitations of existing RIS and relay technologies, this invention provides a downlink NOMA coverage enhancement method based on a STAR-RIS and relay integrated system, which can improve the sum of achievable rates for two users when system power or the number of STAR-RIS components is limited.

[0008] Firstly, a downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated systems is provided. The method includes: constructing a signal transmission model of the integrated system; establishing a system rate maximization problem, with optimization variables being the NOMA power allocation between the base station and relay for two users and the energy splitting coefficient of STAR-RIS; and utilizing the idea of ​​two-stage relay system traffic balancing to determine the power allocated by the base station to... Transmission power Base station allocation Transmission power Relay allocation Transmission power Relay allocation Transmission power The relationship between these four power values ​​is established; a two-level iterative joint optimization method is constructed to obtain the optimal solution of the system.

[0009] Furthermore, the construction of the integrated system signal transmission model includes: the signal transmission model consists of a base station (BS), STAR-RIS, DF relay, reflecting users, and transmitting users. The base station and the two users are each equipped with a single antenna. Since there is no direct link between the blocking base station and the two users, the reflecting users are closer to the base station than the transmitting users. STAR-RIS employs an energy splitting protocol. Composed of several electromagnetic components, the DF relay operates in half-duplex mode; the first time slot base station transmits superimposed signals. The STAR-RIS and DF relay integration device will provide the superimposed signal to the STAR-RIS. Reflected and transmitted to the user respectively Heyuan users DF relay for the superimposed signal Decode and re-encode; the re-encoded signal is transmitted via DF relay in the second time slot. Give it to the two users.

[0010] Furthermore, a system rate and maximization problem is established, with the optimization variables being the NOMA power allocation for the base station and relay to two users and the STAR-RIS energy splitting coefficient. The method also includes: [the following text appears to be incomplete and requires further context: "in two time slots..."] and The signals decoded by each user are combined by maximum ratio to obtain the total SNR at the two users, thus establishing a system rate maximization problem.

[0011] Furthermore, utilizing the concept of two-stage relay system traffic balancing, the relationship between the four power values ​​is determined. The method further includes: for the STAR-RIS and DF relay integrated system, when the inflow and outflow rates of the integrated device are approximately the same, a higher system speed can be achieved; when the SINR at the relay and user locations in the two time slots is equal, the system is in traffic balance, thereby obtaining the four power values ​​allocated by the base station and relay to the two users. , , , The relationship between them.

[0012] Furthermore, a two-layer iterative joint optimization method is constructed to obtain the optimal solution of the system. This method further includes: the outer layer iterates the STAR-RIS energy splitting coefficient. Find a suitable step value based on actual needs. Each loop Plus Then iteratively search for the optimal value; in Under the premise that the inner iteration pre-calculates the total system power Divided into and Two parts, of which, This indicates the power allocated by the base station and relays to the 1st and 3rd links. This indicates the power allocated by the base station and relays to the 2nd and 4th links. To ensure the smooth execution of continuous interference cancellation in downlink NOMA, the following requirements must be met. as well as Set initial value , In each iteration, the step value is added to and subtracted from both respectively. To obtain the optimal power value.

[0013] Furthermore, the method also includes: setting the channel coefficients between the base station and the DF relay and STAR-RIS, and between the DF relay and STAR-RIS and the two users, to be... , , , , , Set the diagonal matrix of STAR-RIS's transmission coefficient. and reflection coefficient diagonal matrix The channel matrix and the coefficient matrix of STAR-RIS are used as inputs to the two-layer iterative joint optimization method to obtain the optimal system rate.

[0014] Secondly, a downlink NOMA coverage enhancement device based on STAR-RIS and a relay integrated system is provided, comprising:

[0015] The setting unit is used to set the channel coefficients between the base station and the DF relay and STAR-RIS, and between the DF relay and STAR-RIS and the two users, and to set the transmission coefficient diagonal matrix of STAR-RIS. and reflection coefficient diagonal matrix ;

[0016] The acquisition unit is used to acquire the received signals at the DF relay and the two users based on the system model;

[0017] The receiving unit is used to decode the received signal to obtain the corresponding SINR;

[0018] The acquisition unit is used to perform maximum ratio combining of the signals decoded at the two time slot users to establish the system rate and maximize the problem.

[0019] The acquisition unit is used to obtain the four power values ​​by utilizing the concept of flow balancing in a two-stage relay system. , , , The relationship between them;

[0020] The unit is obtained, and a two-layer iterative joint optimization algorithm is constructed to obtain the optimal values ​​of the power value and the STAR-RIS energy splitting coefficient.

[0021] Thirdly, this application provides an electronic device, characterized in that it includes: a processor and a memory, the memory being coupled to the processor, the memory being used to store computer program code, the computer program code including computer instructions, wherein when the processor reads the computer instructions from the memory, the electronic device causes the electronic device to execute a downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated systems.

[0022] Fourthly, this application provides a computer storage medium including computer instructions that, when executed on a terminal, cause the terminal to perform the downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system as described in the first aspect.

[0023] Fifthly, this application provides a computer program product that, when the computer program product is run on a computer, causes the computer to execute the downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system as described in the first aspect.

[0024] By integrating STAR-RIS with HDDF relays and combining it with NOMA technology, a two-stage iterative joint optimization method is proposed, utilizing the concept of two-stage system traffic balancing. This method maximizes the sum of the rates for two users in the system by jointly optimizing the NOMA power allocation at the base station and relays, as well as the energy splitting coefficient of STAR-RIS. The proposed solution provides a flexible and efficient approach for coverage enhancement in future wireless networks.

[0025] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a communication scenario diagram after the application system model is constructed in the embodiments of this application;

[0028] Figure 2 A flowchart of a downlink NOMA coverage enhancement method based on STAR-RIS and a relay integration system is provided for embodiments of this application;

[0029] Figure 3 This is a flowchart illustrating the signal transmission process of the application system in an embodiment of this application.

[0030] Figure 4 The algorithm diagram for the proposed two-layer iterative joint optimization method is shown below.

[0031] Figure 5 This is a schematic diagram of a downlink NOMA coverage enhancement device based on STAR-RIS and a relay integration system, as illustrated in this application.

[0032] Figure 6 This is a schematic diagram of the structure of an electronic device as an example of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that, as Figure 1 The scenario illustrated in this invention involves two single-antenna users and a base station equipped with one omnidirectional antenna, where there is no direct link between the base station and the two users due to congestion. Located in the reflective area, user Located in the transmission region, and It is closer to BS than BS.

[0035] It should also be noted that this application considers a downlink NOMA link based on STAR-RIS and a relay integration system. The STAR-RIS provided in this application consists of... It consists of several reflective elements, employs an energy splitting protocol, and intelligent phase adjustment is performed under ideal Channel State Information (CSI) conditions. The DF relay operates in half-duplex mode.

[0036] Figure 2 A flowchart of a downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system is provided for one embodiment of this application, as shown below. Figure 2 As shown, the method is as follows:

[0037] S201: Construct an integrated system signal transmission model.

[0038] It should also be noted that constructing an integrated system signal transmission model includes:

[0039] S301: As Figure 1 As shown, the signal transmission model consists of a base station, STAR-RIS, DF relay, reflecting users, and transmitting users. The base station and the two users are each equipped with a single antenna. Due to the congestion, there is no direct link between the base station and the two users. The reflecting users are closer to the base station than the transmitting users. STAR-RIS uses an energy splitting protocol. It consists of several electromagnetic components, and the DF repeater operates in half-duplex mode.

[0040] S302: As Figure 3 As shown, the superposition coding (SC) signal transmitted by the BS in the first time slot is as follows:

[0041] (1)

[0042] in, and These are the BS assigned to users and The transmission power, To send Information to satisfy Due to the assumption and Compared to BS, it is closer to the relay to Channel gain Greater than from relay to Channel gain ,Right now In downlink NOMA, messages from high-channel-gain users are transmitted at low power levels, while messages from low-channel-gain users are transmitted at high power levels. .

[0043] The superimposed signal in the first time slot The signal is transmitted to two users via STAR-RIS reflection or transmission, thus the first time slot user... and The received signal at that location can be represented as:

[0044] (2)

[0045] (3)

[0046] in, , and These represent BS to STAR-RIS and STAT-RIS to user, respectively. and The channel, The first time slot and Additive white Gaussian noise at the location, and There are two The diagonal matrices, denoted as STAR-RIS transmission coefficient and reflection coefficient matrices respectively, are defined as follows: and ,in and They represent the STAR-RIS number 1, 2, 3, 4, 5, 6, 7, 8 The transmission and reflection coefficients of each element. Considering STAR-RIS based on passive and lossless element surfaces, the sum of the energies of the reflected and transmitted signals must equal the energy of the incident signal, which needs to satisfy .

[0047] Just decode And If considered as noise, the corresponding SINR is:

[0048] (4)

[0049] According to NOMA, in the first time slot Decoding is required sequentially. and The corresponding SINRs are as follows:

[0050] (5)

[0051] (6)

[0052] The received signal at the relay in the first time slot can be represented as:

[0053] (7)

[0054] in, Used to represent the channel from BS to DF relay, The additive white Gaussian noise at the relay point has a variance of . The relay received the signal. It will then be decoded and re-encoded for forwarding information in the second time slot. The DF relay will first... Decode as noise Then, through Successive Interference Cancellation (SIC), Remove from superimposed signals, then... Decoding is performed. Therefore, relay decoding... and The SINR values ​​at the following times are:

[0055] (8)

[0056] (9)

[0057] S303: In the second time slot, the DF relay re-encodes the superimposed signal and transmits the superimposed signal as follows:

[0058] (10)

[0059] in and These are relays for and To ensure fairness among receiving nodes, the transmit power is assumed to be [specified]. Through an ideal DF relay, the second time slot and The received signals at each location can be represented as follows:

[0060] (11)

[0061] (12)

[0062] in and These represent the distance from the relay to the user. and The channel, The second time slot and Additive white Gaussian noise at that location. Similar to the first time slot, the second time slot... Just decode The corresponding SINR is:

[0063] (13)

[0064] Decoding is required sequentially. and And the corresponding SINR is defined as:

[0065] (14)

[0066] (15)

[0067] For ease of explanation, let the channel gain from the base station to STAR-RIS be... STAR-RIS to user channel gain , Channel gain from DF relay to the reflecting user Channel gain from DF relay to transmission user .

[0068] S202: Establish a system rate and maximization problem, with the optimization variables being the NOMA power allocation for two users by the base station and relay, and the energy splitting coefficient of STAR-RIS.

[0069] It should also be noted that the system rate and maximization problem involves optimizing the NOMA power allocation for the two users by the base station and relay, along with the STAR-RIS energy splitting coefficient. and To obtain better information quality, information will be received and decoded in two separate time slots. and Performing Maximum Ratio Combining (MRC) yields the result... and The total SNRs are as follows:

[0070] (16)

[0071] (17)

[0072] Assuming that the energy splitting coefficients of all STAR-RIS components remain consistent, i.e. , ,in, This represents the transmission energy splitting coefficient of STAR-RIS. Furthermore, to achieve phase consistency across all signals at the receiving end and maximize SNR, it is assumed that STAR-RIS has already achieved optimal phase shift. The goal is to achieve this through joint optimization. , , , , as well as The value is used to maximize the sum of the achievable rates for the two users in the system, i.e.

[0073] (18)

[0074] To ensure the successful execution of SIC in NOMA scenarios , , It needs to be greater than a certain threshold value In addition, the total power must also be met. The constraints mean that the optimization problem is as follows:

[0075] (19)

[0076] st (20)

[0077] (twenty one)

[0078] (twenty two)

[0079] (twenty three)

[0080] (twenty four)

[0081] (25)

[0082] The above optimization problem is carried out under the conditions of satisfying the total power constraint, the power non-negativity constraint, and the energy splitting coefficient constraint.

[0083] S203: Utilizing the concept of two-stage relay system flow balancing, the SINR at the relay point and the user point are made equal, and the relationship between the four power values ​​is determined based on the formula derivation.

[0084] It should also be noted that, using the two-stage traffic balancing concept, the relationship between the power values ​​allocated to two users by the base station and the relay station is obtained, including:

[0085] S401: According to observation, maximizing any minimum value in formula (18) will cause the variables contained therein to tend to a balanced result, otherwise it will cause unnecessary waste of resources. Therefore, for the two-stage transmission system integrating STAR-RIS and relay proposed in this invention, the two are regarded as a whole. When the "inflow" and "outflow" rates of the integrated device are roughly the same, a higher achievable rate can be achieved. This goal is called flow balance.

[0086] S402: The system rate is maximized when the SINR at the relay and user locations in the two time slots is equal, and the power relationship can be determined according to formulas (26) and (27) in the specification. Using the flow balance theory, let... , According to the formula derivation, we can obtain:

[0087] (26)

[0088] (27)

[0089] in , , From the two formulas above, given or In this case, the relationship between the four power values ​​can be determined.

[0090] S204: Construct a two-level iterative joint optimization method to obtain the optimal solution of the system.

[0091] It should also be noted that the construction of a two-level iterative joint optimization method to obtain the optimal solution of the system includes:

[0092] S501: This invention utilizes the interrelationships between the power values ​​to design a two-layer iterative joint optimization method, such as... Figure 4 As shown in Algorithm 1, the outermost iteration iterates over the energy splitting coefficient. ,because Find a suitable step value based on actual needs, and iterate through each loop. This fixed value will be added to all values, and then the optimal value will be searched iteratively. In addition, in order to satisfy the SIC constraint of formula (21), It obviously cannot be equal to 0, therefore it needs to be from... Start iterating.

[0093] S502: For inner iterations, given... Under the premise of, in advance Divided into two parts, and To ensure the smooth execution of the SIC process in downlink NOMA, the following requirements must be met. as well as Therefore, in the algorithm, the initial values ​​of these four powers are set to... , In other words, only the lower branches initially contribute to the overall achievable speed. Furthermore, setting... , , and a small value This is used to adjust the power level to gradually satisfy equations (26) and (27). By... and Add together, and from Subtract It can not only calculate the power values ​​that satisfy equations (26) and (27), but also calculate the power values ​​that satisfy equations (26) and (27). Whenever a larger one is found When the power value is updated, the corresponding power value will be updated. Finally, since the SIC constraints in equations (20), (21) and (22) guarantee the success of NOMA, it is necessary to check whether the obtained power meets these constraints. If it does not meet them, it means the end of the inner iteration.

[0094] After constructing the two-level iterative joint optimization method, the method further includes:

[0095] S205: Set the channel coefficients between the base station and the DF relay and STAR-RIS, and between the DF relay and STAR-RIS and the two users as follows: , , , , , Set the diagonal matrix of STAR-RIS's transmission coefficient. and reflection coefficient diagonal matrix ;

[0096] S206: Using the channel matrix and the coefficient matrix of STAR-RIS as inputs to the two-layer iterative joint optimization method, the optimal system rate is obtained.

[0097] Because the integrated system combines STAR-RIS and DF relays, channel estimation overhead can be reduced. When system power or the number of STAR-RIS components is limited, relays can be activated to achieve better performance, and vice versa to save energy. This invention provides a new method for combining RIS and relay technology, offering a flexible and efficient solution for coverage enhancement in future wireless networks.

[0098] When using integrated units, Figure 5 A schematic diagram of a downlink NOMA coverage enhancement device based on STAR-RIS and a relay integration system, as described in the above embodiments, is shown. The device includes: a setting unit 501 and an obtaining unit 502.

[0099] Setting unit 501 is used to set the channel coefficients between the base station and the DF relay and STAR-RIS, and between the DF relay and STAR-RIS and the two users, and to set the transmission coefficient diagonal matrix of STAR-RIS. and reflection coefficient diagonal matrix ;

[0100] The acquisition unit 502 is used to acquire the received signals at the DF relay and the two users according to the system model;

[0101] The receiving unit 502 is used to decode the received signal to obtain the corresponding SINR;

[0102] Unit 502 is used to perform maximum ratio combining on the signals decoded at the two time slot users to establish the system rate and maximization problem;

[0103] Unit 502 is used to obtain the four power values ​​by utilizing the concept of flow balancing in a two-stage relay system. , , , The relationship between them;

[0104] Unit 502 is obtained, and a two-layer iterative joint optimization algorithm is constructed to obtain the optimal values ​​of the power value and the STAR-RIS energy splitting coefficient.

[0105] It should also be noted that, for the sake of convenience and brevity, the specific working process of the downlink NOMA coverage enhancement device based on STAR-RIS and relay integration system described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0106] Figure 6 This is a schematic diagram of the structure of an electronic device provided in Embodiment 3 of this application, as shown below. Figure 6 As shown, the device may include a processor 601 and a memory 602, the memory 602 being coupled to the processor 601. The memory is used to store computer program code, the computer program code including computer instructions. When the processor reads the computer instructions from the memory, the electronic device executes the downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system provided in Embodiment 1.

[0107] This application also provides a computer-readable storage medium that may include a computer program or instructions that, when executed on a computer, cause the computer to perform the downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system described in the above embodiments.

[0108] This application provides a computer program product, including a computer program or instructions, which, when executed on a computer, cause the computer to perform the downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system described in the above embodiments.

[0109] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented using software programs, the above embodiments can appear, in whole or in part, as a computer program product, which includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to the embodiments of this application are generated.

[0110] It should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0111] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system, characterized in that, The method includes: An integrated system signal transmission model is constructed, which consists of a base station, STAR-RIS, a decode-and-forward (DF) relay, and a reflection user. Transmission user The system consists of a base station and two users, each equipped with a single antenna. Due to the lack of a direct link between the base station and the two users, the antennas reflect off the user. Compared to transmission users Closer to the base station, STAR-RIS employs an energy splitting protocol and consists of N electromagnetic components; the DF relay operates in half-duplex mode. In the first time slot, the base station transmits superimposed signals. For STAR-RIS and DF relay integration equipment, among which , To send The information, STAR-RIS will superimpose the signal Reflection and transmission respectively and DF relay for the superimposed signal Decoding and re-encoding are performed; in the second time slot, the DF relay transmits the re-encoded signal. To the two users; Establish a system rate and maximization problem, with the optimization variable being the base station allocation... Transmission power Base station assigned Transmission power Relay allocation Transmission power Relay allocation Transmission power STAR-RIS reflection energy splitting coefficient and transmission energy splitting coefficient Specifically, based on the formula Establish system rate and maximization objective, where, This represents the SINR when the DF relay decodes the i-th user signal. Let represent the total SINR of the signals received by the i-th user in two time slots after maximum ratio combining, and satisfy the following constraints: ; ; ; ; ,in ; ;in, , , , , ;in, This indicates the channel from the BS to the DF relay. , They represent relays to Channel gain and relay to Channel gain, , , These respectively represent BS to STAR-RIS and STAT-RIS to user. and The channel; Utilizing the concept of two-stage relay system traffic balancing, based on ; ; ; ; ; ;in, and These represent the SINR corresponding to the first time slot, and These represent the SINR corresponding to the second time slot, and These are the transmission and reflection coefficient matrices of STAR-RIS, respectively. Let be the variance of additive white Gaussian noise, and let . ,Depend on Determine the transmit power allocated by the relay to the reflecting user. Transmit power allocated by the base station to the reflecting user The relationship between them is ,Depend on Determine the transmit power allocated by the relay to the transmission user. for ,in, , , ; A two-layer iterative joint optimization method is constructed to obtain the optimal solution of the system: the energy splitting coefficient of the outer iterative STAR-RIS. , And from the step value Start iterating, in each loop Overlay And search for the optimal value; given Under the premise that the inner iteration will reduce the total power of the system Divided into and Two parts, satisfying and ,in , These represent the combined power of the base station and relay on the two user links, respectively; initial values ​​are set. , Each iteration passes Stacked step values , minus Adjust the power level and calculate the power relationship. , , , Update and output the output that maximizes the system speed. , , , , , And the corresponding optimal system rate R.

2. The downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system according to claim 1, characterized in that, Constructing an integrated system signal transmission model, including: The signal transmission model consists of a base station, STAR-RIS, DF relay, reflecting users, and transmitting users. The base station and the two users are each equipped with a single antenna. Due to the congestion, there is no direct link between the base station and the two users. The reflecting users are closer to the base station than the transmitting users. STAR-RIS uses an energy splitting protocol. It consists of several electromagnetic components, and the DF repeater operates in half-duplex mode. In the first time slot, the base station transmits superimposed signals. The STAR-RIS and DF relay integration device will provide the superimposed signal to the STAR-RIS. Reflected and transmitted to the user respectively Heyuan users DF relay for the superimposed signal Decode and then re-encode overlay; In the second time slot, the DF relay transmits the re-overlay encoded signal. Give it to the two users.

3. The downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system according to claim 1, characterized in that, The method establishes a system rate and maximization problem, optimizing variables such as the NOMA power allocation between the base station and relay for two users and the STAR-RIS energy splitting coefficient. The method further includes: Within two time slots and The signals decoded by each user are combined by maximum ratio to obtain the total SINR at the two users, thus establishing the system rate and maximization problem.

4. The downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated system according to claim 1, characterized in that, The method further includes: Set the channel coefficients between the base station and the DF relay and STAR-RIS, and between the DF relay and STAR-RIS and the two users as follows: , , , , , ; Set the diagonal matrix of STAR-RIS's transmission coefficient. and reflection coefficient diagonal matrix ; Using the channel matrix and the STAR-RIS coefficient matrix as inputs to the two-level iterative joint optimization method, the optimal system rate is obtained.

5. A downlink NOMA coverage enhancement device based on STAR-RIS and a relay integrated system, used to implement the downlink NOMA coverage enhancement method based on STAR-RIS and a relay integrated system as described in any one of claims 1 to 4, characterized in that, include: The setting unit is used to set the channel coefficients from the base station to the DF relay. Channel coefficients from base station to STAR-RIS Where N represents the number of electromagnetic components in STAR-RIS, and DF relay to the reflecting user. Channel coefficients DF relay to transmission user Channel coefficients STAR-RIS to Reflection Users Channel coefficients STAR-RIS to Transmission Users Channel coefficients Set the diagonal matrix of STAR-RIS's transmission coefficient. and reflection coefficient diagonal matrix ; The acquisition unit is used to obtain the DF relay and reflection user information based on the integrated system signal transmission model. and transmission users The received signal at the location, the integrated system signal transmission model consists of a base station, STAR-RIS, DF relay, and reflective user. Transmission user The system consists of a base station and two users, each equipped with a single antenna and without a direct link. STAR-RIS uses an energy splitting protocol, and the DF relay operates in half-duplex mode. The receiving unit is used to decode the received signal to obtain the signal from the DF relay. , and two users in two time slots , , , ; The acquisition unit is used to perform maximum ratio combining on the signals decoded at the two time slot users, and to establish a base station allocation to the reflecting users. Transmission power Base stations are allocated to transmission users Transmission power Relays are assigned to reflection users. Transmission power Relays are allocated to transmission users. Transmission power STAR-RIS reflection energy splitting coefficient and transmission energy splitting coefficient To optimize the system rate maximization problem, the optimization objective satisfies the system rate maximization formula. ,in, This represents the SINR when decoding the i-th user signal at the DF relay. Let represent the total SINR of the signals received by the i-th user in two time slots after maximum ratio combining, and satisfy the following constraints: ; ; ; ; ,in ; ;in, , , , , ;in, This indicates the channel from the BS to the DF relay. , They represent relays to Channel gain and relay to Channel gain, , , These respectively represent BS to STAR-RIS and STAT-RIS to user. and The channel; The acquisition unit is used to utilize the flow balancing concept of a two-stage relay system, based on... ; ; ; ; ; ;in, and These represent the SINR corresponding to the first time slot, and These represent the SINR corresponding to the second time slot, and These are the transmission and reflection coefficient matrices of STAR-RIS, respectively. Let be the variance of additive white Gaussian noise, and let . ,Depend on Determine the transmit power allocated by the relay to the reflecting user. Transmit power allocated by the base station to the reflecting user The relationship between them is ,Depend on Determine the transmit power allocated by the relay to the transmission user. for ,in, , , ; Obtaining units is used to construct a two-layer iterative joint optimization algorithm, through outer layer iteration. Inner layer iterative allocation and The optimal values ​​for power and STAR-RIS energy splitting coefficient are obtained through this method.

6. An electronic device, characterized in that, include: A processor and a memory, the memory being coupled to the processor, the memory being used to store computer program code, the computer program code including computer instructions, which, when the processor reads from the memory, cause the electronic device to execute the downlink NOMA coverage enhancement method based on STAR-RIS and relay integrated systems as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The system includes computer instructions that, when executed on a terminal, cause the terminal to perform the downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system as described in any one of claims 1 to 4.

8. A computer program product, characterized in that, When the computer program product is run on a computer, the computer performs the downlink NOMA coverage enhancement method based on STAR-RIS and relay integration system as described in any one of claims 1 to 4.

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