A buffer-aided relay network NOMA / OMA transmission strategy selection method and system

Abstract

The application discloses a kind of buffer auxiliary relay network NOMA / OMA transmission strategy selection method and system, uplink and downlink are combined, form a complete information transmission network of sending end to receiving end, this network contains buffer auxiliary relay auxiliary, and based on maximum secrecy rate, power distribution and transmission strategy are optimized jointly using lyapunov optimization theory, wherein transmission strategy contains flexible selection to transmission link and transmission mode.Simultaneously, the application studies NOMA or OMA transmission system without considering buffer auxiliary, and as benchmark scheme, simulation result shows that adaptive selection transmission strategy can effectively improve the security performance of system, and in transmission system with buffer auxiliary relay, with the increase of buffer auxiliary and capacity upper limit, system secrecy rate improves, but there is upper limit matched with channel.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a method and system for selecting transmission strategies in a buffer-assisted relay network (NOMA / OMA). Background Technology

[0002] Relays can retransmit or forward data signals to extend network transmission distance. Existing relay transmission technologies employ a fixed strategy for sending and receiving. In half-duplex relay systems, a one-to-one transmit / receive strategy is used: data is sent from the transmitter to the relay in one time slot, and the relay immediately forwards the data to the receiver in the next time slot, alternating in this manner. However, this relay transmission strategy is significantly affected by instantaneous channel conditions. Buffer-assisted relay transmission technology can overcome the shortcomings of traditional fixed relay transmission strategies. By setting up a buffer at the relay, the relay can store data sent from the transmitter without adhering to the traditional one-to-one transmit / receive fixed transmission strategy, thus allowing for more flexible selection of transmission strategies and increasing the freedom of link selection.

[0003] In the development of 5G wireless networks, Non-Orthogonal Multiple Access (NOMA) technology has become a forward-looking technology for future resource-constrained mobile networks due to its superior performance, including low network latency, large-scale device access capability, improved user fairness, and high throughput. It is also an important principle in wireless access technology design. Compared to traditional Orthogonal Multiple Access (OMA) technology, its core idea is to provide services to multiple users within the same resource block, while OMA can only provide services to a single user. Therefore, NOMA systems place greater emphasis on improving user fairness and generally achieve better performance than OMA systems.

[0004] Current literature considers NOMA transmission systems with buffer-assisted relays, including but not limited to studies on throughput-based link selection strategies, buffer state-based link selection strategies, and power allocation-based link selection strategies. Some studies indicate that OMA performance may outperform NOMA when the channel power gain of two users is not significantly different. Therefore, hybrid NOMA / OMA transmission systems with buffer-assisted relays have attracted considerable attention from researchers, with current focus primarily on either the uplink or downlink. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method and system for selecting NOMA / OMA transmission strategies in a buffer-assisted relay network. This method considers the confidentiality rate under different strategies and the balance between sending and receiving data in the buffer at the relay in a dynamic system. It is used to solve the technical problems of traditional relays, such as instant transmission and reception, low degree of freedom in information transmission, and easy loss of information transmission packets, thereby optimizing the performance of traditional solutions.

[0006] The present invention adopts the following technical solution:

[0007] A method for selecting transmission strategies in a buffer-assisted relay network (NOMA / OMA) is proposed. Based on an information security transmission system model, a link service quality model between the source node and the relay node, a node forwarding capability model between the relay node and the destination node, and an information eavesdropping model between the eavesdropping node and the source node and relay nodes are constructed. A transmission strategy selection mechanism is built based on these models. The average security level of the transmission system is calculated using Lyapunov optimization theory, and a drift plus utility minimization problem is constructed. Finally, based on the transmission strategy selection mechanism, a transmission strategy is selected by minimizing the drift plus utility problem related to the average security level of the transmission system.

[0008] Specifically, the information security transmission system model includes transmitters S1 and S2, destination nodes D1 and D2, relay node R, and eavesdropping node E. Transmitters S1 and S2 communicate securely with their corresponding destination nodes D1 and D2 through relay node R. Relay node R is equipped with buffers Q1 and Q2, which are used to store data from transmitters S1 and S2, respectively.

[0009] Specifically, the quality of service model for the link between the source node and the relay node is constructed as follows:

[0010] When transmitters S1 and S2 use NOMA technology to transmit privacy information, the signal y received at relay node R is determined. r (t) is:

[0011]

[0012] Among them, h sir (i = 1, 2) represents the channel coefficients from transmitter to relay and relay to destination, p s1 (t) and p s2 (t) represent the transmission powers of S1 and S2 at time t, respectively, and the maximum transmission power of transmitters S1 and S2 is P. s x1(t) and x2(t) are the transmitted signals from transmitters S1 and S2, respectively, and n r(t) represents the received noise of relay node R;

[0013] When transmitters S1 and S2 use OMA technology to transmit privacy information, the signals y received by different buffers Q1 and Q2 at relay node R are determined. ri (t) is:

[0014]

[0015] Where i = 1 or i = 2.

[0016] Specifically, the node forwarding capability model between relay nodes and destination nodes is constructed as follows:

[0017] In time slot t, when relay node R uses NOMA technology to forward privacy information, the receiving node D is determined. i Received signal at the location for:

[0018]

[0019] Where i = 1, 2, and These are the transmission powers of relay node R forwarding information from transmitters S1 and S2 to destination nodes D1 and D2, respectively; P r x is the maximum transmit power of relay node R. r1 (t) and x r2 (t) represents the privacy signals of transmitters S1 and S2, n i (t) and n e (t) represent the destination node D. i And the received noise of the eavesdropping node E;

[0020] When relay node R uses OMA technology to transmit privacy information, the destination node D is determined. i and the signal received at eavesdropping node E for:

[0021]

[0022] Where i = 1 or i = 2.

[0023] Specifically, the method for constructing an information eavesdropping model between the eavesdropping node and the source node and relay node is as follows:

[0024] When transmitters S1 and S2 use NOMA technology to transmit privacy information, the signal y received at the eavesdropping node E is determined. e (t) is:

[0025]

[0026] in, Indicates transmitter S i The channel coefficient to the eavesdropping node, n e (t) represents the received noise of E;

[0027] When transmitters S1 and S2 use OMA technology to transmit privacy information, the signal y received at the eavesdropping node E is determined. e (t) is:

[0028]

[0029] in, x represents the transmission power of transmitters S1 and S2. i (t) represents the transmitted signals of transmitters S1 and S2, where i = 1 or i = 2;

[0030] When a relay node uses NOMA technology to transmit private information, determine the signal y received at the eavesdropping node E. e (t) is:

[0031]

[0032] in, Indicates transmitter S i The channel coefficients to the eavesdropping node, i = 1, 2;

[0033] When a relay node uses OMA technology to transmit private information, the signal y received at the eavesdropping node E is determined. e (t) is:

[0034]

[0035] in, The forwarding power allocated to relaying messages through two buffers, x i (t) represents the privacy signal recovered by the relay from transmitters S1 and S2, where i = 1 or i = 2.

[0036] Specifically, the transmission strategy selection mechanism is as follows:

[0037] Transmitters S1 and S2 employ the NOMA secure transmission scheme; transmitter S1 or S2 employs the OMA secure transmission scheme; relay node R employs the NOMA secure transmission scheme; relay node R employs the OMA secure transmission scheme; eavesdropping node E uses SIC technology to decode the acquired information.

[0038] Furthermore, the optimization problem for transmitters S1 and S2 using the NOMA secure transmission scheme is as follows:

[0039]

[0040]

[0041]

[0042]

[0043] The OMA secure transmission scheme used by transmitter S1 or S2 is as follows:

[0044]

[0045]

[0046] The relay node R uses the NOMA secure transmission scheme as follows:

[0047]

[0048]

[0049]

[0050]

[0051] The relay node R uses the OMA secure transmission scheme as follows:

[0052]

[0053]

[0054]

[0055]

[0056] Among them, Q i (t) represents the information value stored in the i-th buffer of relay R at time t. Let R be the actual transmission rate between the i-th transmitter and the relay R. Assign a power value, P, to the i-th transmitter. s q represents the maximum transmitter power. i (t) is defined as an integer with values ​​of 0 and 1, where different values ​​represent different link selections and transmission mode selections. Let R be the theoretical maximum transmission rate between the i-th transmitter and the relay R. Let V and θ be the Lyapunov theoretical control parameters. Power used for forwarding information in the i-th buffer of relay R, P r This represents the theoretical maximum power of relay forwarding information.

[0057] Furthermore, the drift plus utility minimization problem specifically refers to:

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] Where V and θ are the control parameters that balance queue stability and maximize long-term confidentiality. Let Q be the actual transmission rate between the i-th transmitter and the relay R. i Θ(t) represents the information value stored in the i-th buffer of relay R at time t, and Θ(t) represents the set of parameters under long-term average at time t. Assign a power value, P, to the i-th transmitter. s P is the maximum transmitter power. r This represents the theoretical maximum power of relay forwarding information.

[0064] Furthermore, the drift-plus-utility function is as follows:

[0065] Δ(Θ(t))-VE{R sec |Θ(t)}

[0066] Among them, R sec This refers to the actual secure information transmission rate.

[0067] Secondly, embodiments of the present invention provide a buffer-assisted relay network NOMA / OMA transmission strategy selection system, characterized in that it includes:

[0068] The module constructs a link service quality model between the source node and the relay node, a node forwarding capability model between the relay node and the destination node, and an information eavesdropping model between the eavesdropping node and the source node and the relay node, based on the information security transmission system model.

[0069] The strategy module constructs a transmission strategy selection mechanism based on the link service quality model between the source node and the relay node, the node forwarding capability model between the relay node and the destination node, and the information eavesdropping model between the eavesdropping node and the source node and the relay node.

[0070] The optimization module calculates the average security rate of the transmission system using Lyapunov optimization theory and constructs a drift plus utility minimization problem.

[0071] The selection module, based on the transmission strategy selection mechanism obtained from the strategy module, combines the drift and utility minimization problem of the average confidentiality rate of the transmission system obtained from the optimization module to select the transmission strategy.

[0072] Compared with the prior art, the present invention has at least the following beneficial effects:

[0073] A method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network is proposed. This method combines the uplink and downlink to form a complete sender-to-receiver information transmission network. This network incorporates buffer-assisted relay assistance and, based on maximizing security, utilizes Lyapunov optimization theory to jointly optimize power allocation and transmission strategy. The transmission strategy includes flexible selection of transmission links (uplink / downlink) and transmission modes (NOMA / OMA). Simultaneously, NOMA or OMA transmission systems without buffer assistance are investigated and used as benchmark schemes. Simulation results show that adaptive transmission strategy selection effectively improves system security performance. Furthermore, in transmission systems with buffer-assisted relays, the system security improves with increasing buffer assistance and capacity limits, but there is an upper limit for matching the channel.

[0074] Furthermore, an information security transmission system model is constructed, comprising two transmitters, two destination nodes, a relay station equipped with two buffers, and an eavesdropping node. The purpose of the two transmitters, S1 and S2, is to securely communicate with their respective destinations D1 and D2, but the transmission process is threatened by eavesdropping from an eavesdropper, E. There is no direct communication link between the transmitters and destinations; secure information transmission is assisted by the relay node R, which is equipped with two buffers, Q1 and Q2, used to store data from S1 and S2, respectively.

[0075] Furthermore, based on the link service quality model between the source node and the relay node, the node forwarding capability model between the relay node and the destination node, and the information eavesdropping model between the eavesdropping node and the source node and relay node, a transmission strategy selection mechanism is constructed, specifically including: (a) S1 and S2 adopt the NOMA secure transmission scheme; (b) S1 and S2 adopt the OMA secure transmission scheme; (c) R adopts the NOMA secure transmission scheme; (d) R adopts the OMA secure transmission scheme. Combining CSI and other information, selecting the strategy that maximizes the objective function can improve the long-term average confidentiality rate, thereby optimizing the system's secure transmission rate.

[0076] Furthermore, two transmission mechanisms, NOMA and OMA, are introduced. Traditional cellular communication systems primarily use Orthogonal Multiple Access (OMA), which can easily separate the information carried by different user signals with low complexity. However, a drawback of OMA is that the number of users it supports is limited by the amount of available orthogonal resources. If limited to OMA alone, it's impossible to connect more users within limited resources, thus failing to meet the spectral efficiency and massive connectivity requirements of 5G. NOMA, on the other hand, enables the reuse of limited spectrum resources by separating each user's data at the receiving end using advanced receiver technology. Compared to OMA, NOMA significantly improves transmission rates and system capacity, and also offers greater advantages in user fairness, scheduling flexibility, and overall transmission rate.

[0077] Furthermore, we introduce the Lyapunov optimization theory and define the Lyapunov function. To maintain queue stability and maximize the average security rate, we obtain the drift plus utility function through theoretical analysis. By combining the long-term security rate maximization problem with the Lyapunov framework, we express the optimization problem as drift plus utility minimization, which simplifies the computational complexity. We rewrite the multi-slot optimization problem as a single-slot security rate maximization problem, thus facilitating the solution of the problem.

[0078] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0079] In summary, this invention effectively considers the system confidentiality rate under different transmission links and transmission methods, and maximizes the system's secure transmission rate.

[0080] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0081] Figure 1 Diagram of a buffer-assisted relay network system;

[0082] Figure 2 This is a schematic diagram illustrating the relationship between security level and signal-to-noise ratio.

[0083] Figure 3 This is a diagram illustrating the relationship between security level and eavesdropping distance.

[0084] Figure 4 This is a diagram illustrating the relationship between the security level and the upper limit of the buffer capacity. Detailed Implementation

[0085] 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, not all, of the embodiments of the present invention. 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.

[0086] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0087] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0088] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0089] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0090] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0091] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0092] This invention provides a method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network. It combines the uplink and downlink to form a complete sender-to-receiver information transmission network. This network incorporates buffer-assisted relay assistance and, based on maximizing security, utilizes Lyapunov optimization theory to jointly optimize power allocation and transmission strategy. The transmission strategy includes flexible selection of transmission links (uplink / downlink) and transmission modes (NOMA / OMA). Furthermore, this invention studies NOMA or OMA transmission systems without considering buffer assistance, using them as benchmark schemes. Simulation results show that adaptive transmission strategy selection effectively improves system security performance. In transmission systems with buffer-assisted relays, the system security improves with increasing buffer assistance and capacity limits, but there is an upper limit to channel matching.

[0093] Please see Figure 1 The present invention provides a method for selecting a NOMA / OMA transmission strategy in a buffer-assisted relay network, comprising the following steps:

[0094] S1. Construct an information security transmission system model consisting of 2 transmitters, 2 destination nodes, a relay node equipped with 2 buffers, and a listening node;

[0095] In the information security transmission system model, the purpose of the two transmitters S1 and S2 is to communicate securely with their respective destinations D1 and D2, but the transmission process is threatened by eavesdropping by an eavesdropper E.

[0096] There is no direct communication between the transmitter and the destination. Secure transmission of information is assisted by relay node R. The relay station is equipped with two buffers, Q1 and Q2, which are used to store data from S1 and S2, respectively.

[0097] S2. Based on this information security transmission system model, construct a link service quality model between the source node and the relay node;

[0098] S201. If transmitters S1 and S2 use NOMA technology to transmit privacy information, determine the signal received at node R.

[0099] The signal received at node R is represented as follows:

[0100]

[0101] in, This represents the channel coefficients from transmitter to relay and relay to destination. and These are the transmission powers of S1 and S2 at time t, respectively, and the maximum transmission power of transmitters S1 and S2 is P. s x1(t) and x2(t) are the transmitted signals of S1 and S2, respectively, and they satisfy E{|x1(t)| 2}=1 and E{|x2(t)| 2}=1, n r (t) represents the received noise of R.

[0102] S202. If transmitters S1 and S2 use OMA technology to transmit privacy information, determine the signals received by different buffers Q1 and Q2 at node R.

[0103] The signals received by different buffers Q1 and Q2 at node R are represented as follows:

[0104]

[0105] Where i = 1 or i = 2.

[0106] S3. Based on this information security transmission system model, construct a node forwarding capability model between relay nodes and destination nodes;

[0107] S301. In time slot t, if R uses NOMA technology to forward privacy information, determine the receiving node D. i The received signal at (i = 1, 2);

[0108] Receiver node D i The received signals at (i=1,2) are represented as follows:

[0109]

[0110] in, and These represent the transmission power of R forwarding S1 and S2 information to destination nodes D1 and D2, respectively; the maximum transmission power of R is denoted as P. r x r1 (t) and x r2 (t) are the privacy signals of S1 and S2, which satisfy E{|x r1 (t)| 2}=1 and E{|x r2 (t)| 2}=1,n i (t) and ne (t) are respectively in D i And the received noise of E.

[0111] S302. If relay node R uses OMA technology to transmit privacy information, determine the destination node D. i The signal received at point E.

[0112] At the destination node D i The signal received at the eavesdropping node E is represented as

[0113]

[0114] Where i = 1 or i = 2.

[0115] S4. Based on this information security transmission system model, construct an information eavesdropping model between the eavesdropping node and the source node and relay node;

[0116] S401. If transmitters S1 and S2 use NOMA technology to transmit privacy information, determine the signal received at the eavesdropping node E.

[0117] The signal received at eavesdropping node E is represented as follows:

[0118]

[0119] in, Indicates transmitter S i The channel coefficient to the eavesdropping node, n e (t) represents the received noise of E.

[0120] S402. If transmitters S1 and S2 use OMA technology to transmit privacy information, determine the signal received at the eavesdropping node E.

[0121] The signal received at eavesdropping node E is represented as follows:

[0122]

[0123] Where i = 1 or i = 2.

[0124] S403. If the relay node uses NOMA technology to transmit privacy information, determine the signal received at the eavesdropping node E.

[0125] The signal received at eavesdropping node E is represented as follows:

[0126]

[0127] in, Indicates transmitter S i The channel coefficient to the eavesdropping node.

[0128] S404. If the relay node uses OMA technology to transmit privacy information, determine the signal received at the eavesdropping node E.

[0129] The signal received at eavesdropping node E is represented as follows:

[0130]

[0131] Where i = 1 or i = 2.

[0132] S5. Based on the link service quality model between the source node and the relay node, the node forwarding capability model between the relay node and the destination node, and the information eavesdropping model between the eavesdropping node and the source node and the relay node, a transmission strategy selection mechanism is constructed.

[0133] The transmission strategy selection mechanism specifically includes:

[0134] S1 and S2 use the NOMA secure transmission scheme; S1 and S2 use the OMA secure transmission scheme; R uses the NOMA secure transmission scheme; R uses the OMA secure transmission scheme.

[0135] In these four scenarios, the present invention considers a conservative approach for the eavesdropper, namely, that the eavesdropper also uses SIC technology to decode the acquired information.

[0136] S6. Combining the Lyapunov optimization theory, calculate the average security rate of the transmission system and construct a drift plus utility minimization problem;

[0137] Introducing Lyapunov optimization theory, we define the Lyapunov function. To maintain queue stability and maximize average confidentiality, we obtain the drift plus utility function through theoretical analysis:

[0138] Δ(Θ(t))-VE{R sec |Θ(t)},

[0139] Where V≥0 is the control parameter that balances queue stability and maximizes long-term confidentiality.

[0140] The drift plus utility minimization problem can be written as follows, with the optimization objective being to minimize the drift plus utility function:

[0141]

[0142]

[0143]

[0144]

[0145]

[0146] Among them, Q i (t) represents the information value stored in the i-th buffer of relay R at time t. Let R be the actual transmission rate between the i-th transmitter and the relay R. Assign a power value, P, to the i-th transmitter. s q represents the maximum transmitter power. i q1(t) is defined as an integer value of 0 and 1. q1(t) = 1 indicates that the first hop transmission is used, while q1(t) = 0 indicates that the second hop transmission is used. q2(t) = 1 indicates that the NOMA mode is used for transmission, while q1(t) = 0 indicates that the OMA mode is used for transmission. Let R be the theoretical maximum transmission rate between the i-th transmitter and the relay R. Let V and θ be the Lyapunov theoretical control parameters, and p ri (t) represents the power used for forwarding information in the i-th buffer of relay R, P r for Theoretical maximum value. The above definition specifies i = 1 or i = 2.

[0147] S7. Based on the transmission strategy selection mechanism, the problem of optimizing the average confidentiality rate of the transmission system is discussed in four cases.

[0148] M1: S1 and S2 adopt the NOMA secure transmission scheme. The optimization problem is:

[0149]

[0150]

[0151]

[0152]

[0153] Since Q1(t)≥0 and Q2(t)≥0, the optimal and They should be satisfied separately. and Then the optimal power and Exported as:

[0154]

[0155]

[0156] M2:S1 or S2 uses the OMA secure transmission scheme, as detailed below:

[0157]

[0158]

[0159] M3:R uses the NOMA secure transmission scheme, as detailed below:

[0160]

[0161]

[0162]

[0163]

[0164] M4:R uses the OMA secure transmission scheme, as detailed below:

[0165]

[0166]

[0167]

[0168]

[0169] Among them, Q i (t) represents the information value stored in the i-th buffer of relay R at time t. Let R be the actual transmission rate between the i-th transmitter and the relay R. Assign a power value, P, to the i-th transmitter. s q represents the maximum transmitter power. i q1(t) is defined as an integer value of 0 and 1. q1(t) = 1 indicates that the first hop transmission is used, while q1(t) = 0 indicates that the second hop transmission is used. q2(t) = 1 indicates that the NOMA mode is used for transmission, while q1(t) = 0 indicates that the OMA mode is used for transmission. Let R be the theoretical maximum transmission rate between the i-th transmitter and the relay R. Let V and θ be the Lyapunov theoretical control parameters. Power used for forwarding information in the i-th buffer of relay R, P r for Theoretical maximum value. The above definition specifies i = 1 or i = 2.

[0170] In another embodiment of the present invention, a buffer-assisted relay network (NOMA / OMA) transmission strategy selection system is provided. This system can be used to implement the above-mentioned buffer-assisted relay network (NOMA / OMA) transmission strategy selection method. Specifically, the buffer-assisted relay network (NOMA / OMA) transmission strategy selection system includes a construction module, a strategy module, an optimization module, and a selection module.

[0171] Among them, the construction module constructs a link service quality model between the source node and the relay node, a node forwarding capability model between the relay node and the destination node, and an information eavesdropping model between the eavesdropping node and the source node and the relay node, based on the information security transmission system model.

[0172] The strategy module constructs a transmission strategy selection mechanism based on the link service quality model between the source node and the relay node, the node forwarding capability model between the relay node and the destination node, and the information eavesdropping model between the eavesdropping node and the source node and the relay node.

[0173] The optimization module calculates the average security rate of the transmission system using Lyapunov optimization theory and constructs a drift plus utility minimization problem.

[0174] The selection module, based on the transmission strategy selection mechanism obtained from the strategy module, combines the drift and utility minimization problem of the average confidentiality rate of the transmission system obtained from the optimization module to select the transmission strategy.

[0175] In another embodiment of the present invention, a terminal device is provided, comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to implement a corresponding method flow or corresponding function. The processor described in this embodiment of the present invention can be used for the operation of a buffer-assisted relay network (NOMA / OMA) transmission strategy selection method, including:

[0176] Based on the information security transmission system model, we construct link service quality models between the source node and relay node, node forwarding capability models between the relay node and destination node, and information eavesdropping models between the eavesdropping node and the source node and relay node. Based on these models, we construct a transmission strategy selection mechanism. Using Lyapunov optimization theory, we calculate the average security rate of the transmission system and construct a drift plus utility minimization problem. Finally, based on the transmission strategy selection mechanism, we select a transmission strategy by combining the drift plus utility minimization problem of the average security rate of the transmission system.

[0177] In another embodiment of the present invention, a storage medium is also provided, specifically a computer-readable storage medium (memory). This computer-readable storage medium is a memory device in a terminal device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and extended storage media supported by the terminal device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device.

[0178] One or more instructions stored in a computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the NOMA / OMA transmission strategy selection method for buffer-assisted relay networks in the above embodiments; one or more instructions in the computer-readable storage medium are loaded and executed by the processor to perform the following steps:

[0179] Based on the information security transmission system model, we construct link service quality models between the source node and relay node, node forwarding capability models between the relay node and destination node, and information eavesdropping models between the eavesdropping node and the source node and relay node. Based on these models, we construct a transmission strategy selection mechanism. Using Lyapunov optimization theory, we calculate the average security rate of the transmission system and construct a drift plus utility minimization problem. Finally, based on the transmission strategy selection mechanism, we select a transmission strategy by combining the drift plus utility minimization problem of the average security rate of the transmission system.

[0180] 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0181] This invention studies a secure transmission system in which two transmitters wish to securely send information to their respective destinations with the aid of buffers. For the system under consideration, the proposed scheme is based on Lyapunov optimization theory, balancing long-term security and queue stability by jointly optimizing power allocation and transmission strategies. The transmission strategies include link selection (first hop and second hop) and mode selection (non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA)). Simulation results verify that the proposed scheme outperforms the traditional unbuffered NOMA / OMA transmission system in terms of security.

[0182] In the network, two transmitters, S1 and S2, aim to securely communicate with their respective destinations, D1 and D2, but the transmission process is threatened by eavesdropping by an eavesdropper, E. Due to obstacles and the long transmission distance, there is no direct communication link between the transmitters and the destinations. Secure information transmission is assisted by a relay node R, which is equipped with two buffers, Q1 and Q2, to store data from S1 and S2, respectively. The buffers provided by the relay station offer high-quality, flexible link selection. Furthermore, this paper assumes that all nodes have only one antenna and operate in half-duplex transmission mode. This system can capture device-to-device communication scenarios where two transmitters share limited spectrum resources for secure transmission.

[0183] In this system, each frame is divided into multiple time slots of duration T. All channels follow a flat Rayleigh fading pattern, indicating that channel quality remains constant within a single time slot but varies independently across different time slots. This invention uses... and These represent the channel coefficients from the transmitter to the relay and from the relay to the destination, respectively. and The channel power gains are respectively expressed as

[0184] In addition, privacy information is obtained through channel coefficients respectively and h re The channel is acquired by the eavesdropping node E, where their channel power gains are respectively expressed as... and g re =|h re | 2 .

[0185] The maximum transmission power of transmitters S1 and S2 is P s The maximum transmit power of R is expressed as P. r For legitimate channels, instantaneous channel state information (CSI) is obtained through leader estimation. However, due to passive eavesdropping, eavesdropping CSI cannot be obtained; therefore, channel distribution information (CDI) is assumed to be available. Furthermore, the received noise in this system is circularly symmetric complex zero-mean white Gaussian noise, denoted as N0.

[0186] To improve spectrum efficiency, NOMA technology is used in information transmission, and SIC technology is used in information decoding.

[0187] However, since the channel coefficients are constantly changing, secure NOMA transmission may not be possible, prompting continued consideration of OMA technology. If the transmitter and S2 use NOMA technology to transmit privacy information, the signals received at nodes R and E are represented as follows:

[0188]

[0189] in, and Let S1 and S2 be the transmission powers at time t, respectively; and let x1(t) and x1(t) be the transmission signals of S1 and S2, respectively, which satisfy E{|x1(t)| 2}=1 and E{|x2(t)| 2}=1, n r (t) and n e (t) represents the received noise of R and E, respectively.

[0190] When the OMA strategy is used, the received signal is represented as follows:

[0191]

[0192] Where i = 1 or i = 2. In the t-th time slot, if R uses NOMA technology to forward privacy information, then at the receiving node D... i The received signals at (i=1,2) and the eavesdropping node E are respectively represented as follows:

[0193]

[0194] in, and These are the transmission powers of R forwarding S1 and S2 information to destination nodes D1 and D2, respectively; x r1 (t) and x r2 (t) are the privacy signals of S1 and S2, which satisfy E{|x r1 (t)| 2}=1 and E{|x r2 (t)| 2}=1,n i (t) and n e (t) are respectively in D i The received noise of E. In the following text, we will explain the proposed scheme, namely, secure transmission using buffer-assisted relay.

[0195] When a relay node uses the OMA strategy, the received signal is represented as follows:

[0196]

[0197] Where i = 1 or i = 2.

[0198] Simulation verification

[0199] Please see Figure 2 A graph showing the relationship between security level and transmission signal-to-noise ratio (SNR) was plotted. The graph shows that compared to the unbuffered scheme, adding buffers to relay nodes significantly improves the system's security level. This is because the buffer can store information and wait for better channel conditions before transmitting. Compared to using only NOMA or OMA for information transmission, adding mode selection provides better security performance. This is because the system will choose the better mode (NOMA / OMA) instead of using the same mode. For example, when OMA's performance is inferior to NOMA, the system will adaptively choose NOMA, and vice versa. Link selection refers to the system stopping a hop and switching to another hop when the performance of a certain hop is poor. It can be seen that the security performance of a system with link selection is better than that of a system with only mode selection.

[0200] Please see Figure 3 This shows the relationship between security level and distance to the relay / eavesdropping node. As the eavesdropping node becomes farther away, the secure transmission rate increases to some extent under all four transmission strategies, but systems with link selection still outperform those without, and systems with a hybrid NOMA / OMA transmission method outperform those using only one method. Please refer to... Figure 4 This shows the relationship between the system's security level and the maximum buffer capacity. When the buffer capacity reaches its maximum, the first hop cannot send messages; only the second hop can be used. With Q... maxAs the size decreases, the amount of information that can be stored decreases, the flexibility of link selection is limited, and the system's confidentiality gradually declines.

[0201] In summary, this invention provides a method and system for selecting NOMA / OMA transmission strategies in a buffer-assisted relay network. It combines the uplink and downlink to form a complete sender-to-receiver information transmission network. This network incorporates buffer-assisted relays and, based on maximizing security, utilizes Lyapunov optimization theory to jointly optimize power allocation and transmission strategies. The transmission strategy includes flexible selection of transmission links (uplink / downlink) and transmission modes (NOMA / OMA). Furthermore, NOMA or OMA transmission systems without buffer assistance are investigated and used as benchmark schemes. Simulation results show that adaptive transmission strategy selection effectively improves system security performance. In transmission systems with buffer-assisted relays, the system security improves with increasing buffer capacity and capacity limit, but there is an upper limit for matching the channel.

[0202] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0203] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0204] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0205] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or 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 coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0206] 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.

[0207] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0208] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0209] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0210] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0211] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0212] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for selecting a NOMA / OMA transmission strategy in a buffer-assisted relay network, characterized in that, Based on the information security transmission system model, we construct link service quality models between the source node and relay node, node forwarding capability models between the relay node and destination node, and information eavesdropping models between the eavesdropping node and the source node and relay node. Based on these models, we construct a transmission strategy selection mechanism. Using Lyapunov optimization theory, we calculate the average security rate of the transmission system and construct a drift plus utility minimization problem. Finally, based on the transmission strategy selection mechanism, we select a transmission strategy by combining the drift plus utility minimization problem of the average security rate of the transmission system. The transmission strategy selection mechanism is as follows: transmitter and NOMA secure transmission scheme adopted; transmitter or The OMA secure transmission scheme is adopted; relay nodes. NOMA secure transmission scheme adopted; relay node OMA secure transmission scheme adopted; eavesdropping node The acquired information is decoded using SIC technology; transmitter and The optimization problem of using the NOMA secure transmission scheme is as follows: transmitter or The OMA secure transmission scheme is adopted as follows: relay node The NOMA secure transmission scheme is adopted as follows: relay node The OMA secure transmission scheme is adopted as follows: in, for Time relay Equipped with Each buffer stores the information value. For the first One transmitter and relay The actual transmission rate between them For the first Each transmitter is assigned a power value. This represents the maximum transmitter power. Values ​​are defined using integers 0 and 1, with different values ​​representing different link selections and transmission mode selections. For the first One transmitter and relay The theoretical maximum transmission rate between them for, and These are the control parameters according to Lyapunov theory. For relay Equipped with The power used for forwarding information in each buffer. This represents the theoretical maximum power of relayed information. The drift plus utility minimization problem is specifically: in, for Time relay Equipped with Each buffer stores the information value. for The set of parameters under long-term average over time.

2. The method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network according to claim 1, characterized in that, The information security transmission system model includes a transmitter. and , destination node and relay node and eavesdropping nodes transmitter and With the corresponding destination node and Relay nodes For secure communication, relay nodes Equipped with buffer and , buffer and Used respectively for storing transmitters and The data.

3. The method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network according to claim 2, characterized in that, The specific steps for constructing the link service quality model between the source node and the relay node are as follows: When the transmitter and NOMA technology is used to transmit privacy information and determine relay nodes. The signal received at the location for: in, This represents the channel coefficients from transmitter to relay and from relay to destination. , and They are time and The allocated power value of the transmitter and Maximum transmit power is ; and It is a transmitter and The transmitted signal, For relay nodes Received noise; When the transmitter and OMA technology is used to transmit privacy information and determine relay nodes. Different buffers and Received signal for: in, or .

4. The method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network according to claim 3, characterized in that, The specific steps for constructing the node forwarding capability model between the relay node and the destination node are as follows: In the Time slots, as relay nodes Use NOMA technology to forward privacy information and determine the receiving node. Received signal at the location for: in, , and These are relay nodes To the destination node and repeater and Information utilization efficiency; For relay nodes Maximum transmit power, and It is a transmitter and Privacy signals, and They are at the destination node and eavesdropping nodes Received noise; As a relay node OMA technology is used to transmit privacy information and determine the destination node. and eavesdropping nodes The signal received at the location for: in, or .

5. The method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network according to claim 4, characterized in that, The specific steps for constructing an information eavesdropping model between the eavesdropping node and the source node and relay node are as follows: When the transmitter and Using NOMA technology to transmit private information and identify eavesdropping nodes. The signal received at the location for: in, Indicates the transmitter Channel coefficients to the eavesdropping node for Received noise; When the transmitter and Using OMA technology to transmit private information and identify eavesdropping nodes The signal received at the location for: When relay nodes use NOMA technology to transmit private information, the eavesdropping nodes can be identified. The signal received at the location for: in, Indicates the transmitter Channel coefficients to the eavesdropping node ; When relay nodes use OMA technology to transmit private information, the eavesdropping nodes can be identified. The signal received at the location for: 。 6. The method for selecting NOMA / OMA transmission strategy in a buffer-assisted relay network according to claim 5, characterized in that, The drift-plus-utility function is as follows: in, This refers to the actual secure information transmission rate.

7. A buffer-assisted relay network (NOMA / OMA) transmission strategy selection system, utilizing the buffer-assisted relay network (NOMA / OMA) transmission strategy selection method as described in claim 1, characterized in that, include: The module constructs a link service quality model between the source node and the relay node, a node forwarding capability model between the relay node and the destination node, and an information eavesdropping model between the eavesdropping node and the source node and the relay node, based on the information security transmission system model. The strategy module, based on the link service quality model between the source node and the relay node, the node forwarding capability model between the relay node and the destination node, and the information eavesdropping model between the eavesdropping node and the source node and relay nodes, constructs a transmission strategy selection mechanism, specifically as follows: transmitter and NOMA secure transmission scheme adopted; transmitter or The OMA secure transmission scheme is adopted; relay nodes. NOMA secure transmission scheme adopted; relay node OMA secure transmission scheme adopted; eavesdropping node The acquired information is decoded using SIC technology; transmitter and The optimization problem of using the NOMA secure transmission scheme is as follows: transmitter or The OMA secure transmission scheme is adopted as follows: relay node The NOMA secure transmission scheme is adopted as follows: relay node The OMA secure transmission scheme is adopted as follows: in, for Time relay Equipped with Each buffer stores the information value. For the first One transmitter and relay The actual transmission rate between them For the first Each transmitter is assigned a power value. This represents the maximum transmitter power. Values ​​are defined using integers 0 and 1, with different values ​​representing different link selections and transmission mode selections. For the first One transmitter and relay The theoretical maximum transmission rate between them for, and These are the control parameters according to Lyapunov theory. For relay Equipped with The power used for forwarding information in each buffer. This represents the theoretical maximum power of relayed information. The drift plus utility minimization problem is specifically: in, for Time relay Equipped with Each buffer stores the information value. for The set of parameters under long-term time-varying averages; The optimization module calculates the average security rate of the transmission system using Lyapunov optimization theory and constructs a drift plus utility minimization problem. The selection module, based on the transmission strategy selection mechanism obtained from the strategy module, combines the drift and utility minimization problem of the average confidentiality rate of the transmission system obtained from the optimization module to select the transmission strategy.

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