Non-orthogonal multiple access networks and their data transmission methods, apparatus and chip devices

Abstract

This invention discloses a non-orthogonal multiple access network and its data transmission method, apparatus, and chip device. The method includes: obtaining the power division factor of a relay and the power allocation factor of each user terminal; the base station superimposes and encodes the signals of each user terminal, generates and transmits the superimposed signal, and calculates the first signal-to-interference-plus-noise ratio (SNR) of the demodulated signal at each relay, the second SNR of the demodulated signal at each user terminal, and the third SNR of the demodulated signal at the eavesdropper based on the power division factor and the power allocation factor; determining the target relay from N relays based on the first, second, and third SNRs, wherein the target relay is the relay that provides the eavesdropped user terminal with the maximum secure transmission rate; and performing energy harvesting and decoding processing on the superimposed signal through the target relay and forwarding it to each user terminal. This method can improve the energy utilization, bandwidth utilization, and transmission reliability of the non-orthogonal multiple access network.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a non-orthogonal multiple access network and its data transmission method, apparatus and chip device. Background Technology

[0002] Currently, research on energy-constrained transmission strategies mainly focuses on single-relay networks, with only some applications in multi-relay networks. Furthermore, in multi-relay networks, relays with energy harvesting (EH) capabilities increase computational complexity. Therefore, related technologies have simplified the relay operation by employing amplify-and-forward (AF) relays with half-duplex (HD) functionality. However, this can impact the reliability of data transmission. Summary of the Invention

[0003] This invention aims to at least partially address one of the technical problems in related technologies. Therefore, the objective of this invention is to provide a non-orthogonal multiple access network and its data transmission method, apparatus, and chip device to improve reliable data transmission performance.

[0004] In a first aspect, embodiments of the present invention propose a data transmission method for a non-orthogonal multiple access network (NOMA). The NOMA includes a base station, an eavesdropper, N relays, and M user terminals. The base station, the user terminals, and the eavesdropper operate in half-duplex mode, while the relays operate in full-duplex mode and have energy harvesting capabilities. The method includes: obtaining the power division factor of the relays and the power allocation factor of each user terminal; the base station superimposes and encodes the signals of each user terminal, generates and transmits the superimposed signal, and then, based on the power division... The first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each of the relays, the second SIR of the demodulated signal at each of the user terminals, and the third SIR of the demodulated signal at the eavesdropper are calculated using the power allocation factor and the power allocation factor, respectively. Based on the first SIR, the second SIR, and the third SIR, a target relay is determined from the N relays, wherein the target relay is the relay that enables the eavesdropped user terminal to have the maximum secure transmission rate. The superimposed signal is then processed by energy harvesting and decoding through the target relay and forwarded to each of the user terminals.

[0005] In addition, the data transmission method of the non-orthogonal multiple access network according to embodiments of the present invention may also have the following additional technical features:

[0006] According to one embodiment of the present invention, determining a target relay from N relays based on the first signal-to-interference-plus-noise ratio (SIR), the second SIR, and the third SIR includes: determining X candidate relays from the N relays based on the first SIR and the second SIR, wherein the candidate relays are relays that enable each user terminal to meet the minimum transmission rate requirement, and the third SIR is the SIR calculated for each candidate relay when forwarding data, which is the SIR of the signal of the eavesdropped user terminal demodulated at the eavesdropper; and determining the target relay from the X candidate relays based on the third SIR and its corresponding first SIR and second SIR.

[0007] According to an embodiment of the present invention, the method further includes: acquiring the residual self-interference of the relay; and calculating, respectively, a first signal-to-interference-plus-noise ratio (SNR) of the demodulated signal at each of the relays, a second SNR of the demodulated signal at each of the user terminals, and a third SNR of the demodulated signal at the eavesdropper, based on the power division factor, the power allocation factor, and the residual self-interference.

[0008] According to one embodiment of the present invention, determining X candidate relays from N relays based on the first signal-to-interference-plus-noise ratio (SIR) and the second SIR includes: for each relay, calculating the data transmission rate corresponding to the relay based on the first SIR of the signal of each user terminal demodulated at the relay, and the second SIR of the signal of the user terminal demodulated at the user terminal and the signal of the user terminal further away from the base station; and selecting the relays with data transmission rates greater than the corresponding minimum transmission rate as the candidate relays, thereby obtaining X candidate relays.

[0009] According to an embodiment of the present invention, determining the target relay from X candidate relays based on the third signal-to-interference-plus-noise ratio (SNR) and its corresponding first and second SNRs includes: for each candidate relay, calculating the achievable transmission rate of the eavesdropped user terminal based on the first SNR of the signal demodulated at the candidate relay and the second SNR of the signal demodulated at the eavesdropped user terminal; calculating the eavesdropping rate of the eavesdropper on the signal of the eavesdropped user terminal based on the third SNR of the signal demodulated at the eavesdropper; and calculating the secure transmission rate of the eavesdropped user terminal based on the achievable transmission rate and the eavesdropping rate; and selecting the candidate relay corresponding to the maximum secure transmission rate as the target relay.

[0010] According to an embodiment of the present invention, the first signal-to-interference-plus-noise ratio is calculated by the following formula:

[0011]

[0012] in, α represents the first signal-to-interference-plus-noise ratio (SIR) of the signal demodulated at user terminal j at the i-th relay. j α represents the power allocation factor for user terminal j. k p represents the power allocation factor for user terminal k. s β represents the transmit signal-to-noise ratio of the base station, and β represents the power division factor. Let δ represent the channel gain from the base station to the i-th relay, δ represent the residual self-interference factor of the i-th relay, η represent the energy collection efficiency of the relay, and M be the total number of user terminals.

[0013] According to one embodiment of the present invention, the second signal-to-interference-plus-noise ratio is calculated by the following formula:

[0014]

[0015] in, This represents the second signal-to-interference-plus-noise ratio (SIR) of the signal from user terminal k demodulated at user terminal j when the i-th relay forwards data. Let m represent the distance between the i-th relay and the user terminal j, and m represent the path loss factor. Indicates distance power of m Let represent the channel gain from the i-th relay to the user terminal j.

[0016] According to one embodiment of the present invention, the distances between user terminal 1, user terminal 2, ..., user terminal M and the base station decrease sequentially, and X candidate relays are determined from N relays using the following formula:

[0017]

[0018] Where, N r This represents the set consisting of X candidate relays. This represents the data transmission rate corresponding to the i-th relay. This represents the minimum transmission rate of user terminal j.

[0019] According to an embodiment of the present invention, the third signal-to-interference-plus-noise ratio is calculated by the following formula:

[0020]

[0021] in, α represents the third signal-to-interference-plus-noise ratio (SNR) of the signal from user terminal k demodulated at the eavesdropper's location when the i-th relay forwards data. k This represents the power allocation factor for user terminal k. Let represent the channel gain from the i-th relay to the eavesdropper.

[0022] According to one embodiment of the present invention, the eavesdropped user terminal is the user terminal M closest to the base station, and the target relay is obtained by the following formula:

[0023]

[0024] Among them, i * Indicates the target relay, This represents the achievable transmission rate of user terminal M when the i-th candidate relay performs data forwarding; This represents the rate at which the eavesdropper intercepts the signal of the user terminal M when the i-th candidate relay forwards data. This represents the secure transmission rate of the user terminal M when the i-th candidate relay performs data forwarding.

[0025] Secondly, embodiments of the present invention propose a data transmission device for a non-orthogonal multiple access network (NOMA). The NOMA includes a base station, an eavesdropper, N relays, and M user terminals. The base station, user terminals, and eavesdropper operate in half-duplex mode, while the relays operate in full-duplex mode and have energy harvesting capabilities. The device includes: an acquisition module for acquiring the power division factor of the relays and the power allocation factor of each user terminal; and a calculation module for the base station to perform superposition encoding on the signals of each user terminal, generate and transmit the superimposed signal, and then calculate the power division factor based on the power division factor. The power allocation factor and the power allocation factor are used to calculate the first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each of the relays, the second SIR of the demodulated signal at each of the user terminals, and the third SIR of the demodulated signal at the eavesdropper, respectively. A determination module is used to determine a target relay from the N relays based on the first SIR, the second SIR, and the third SIR, wherein the target relay is the relay that provides the eavesdropped user terminal with the maximum secure transmission rate. A transmission module is used to perform energy harvesting and decoding processing on the superimposed signal through the target relay and forward it to each of the user terminals.

[0026] In addition, the data transmission apparatus of the non-orthogonal multiple access network according to embodiments of the present invention may also have the following additional technical features:

[0027] According to an embodiment of the present invention, when determining a target relay from N relays based on the first signal-to-interference-plus-noise ratio (SIR), the second SIR, and the third SIR, the determining module is configured to: determine X candidate relays from the N relays based on the first SIR and the second SIR, wherein the candidate relays are relays that enable each user terminal to meet the minimum transmission rate requirement, and the third SIR is the SIR calculated for each candidate relay when forwarding data, which is the SIR of the signal of the eavesdropped user terminal demodulated at the eavesdropper; and determine the target relay from the X candidate relays based on the third SIR and its corresponding first SIR and second SIR.

[0028] According to one embodiment of the present invention, the acquisition module is further configured to acquire the residual self-interference of the relay; the calculation module is further configured to calculate, based on the power division factor, the power allocation factor and the residual self-interference, a first signal-to-interference-plus-noise ratio (SNR) of the demodulated signal at each of the relays, a second SNR of the demodulated signal at each of the user terminals and a third SNR of the demodulated signal at the eavesdropper.

[0029] According to an embodiment of the present invention, when the determining module determines X candidate relays from N relays based on the first signal-to-interference-plus-noise ratio (SIR) and the second SIR, it is configured to: for each relay, calculate the data transmission rate corresponding to the relay based on the first SIR of the signal of each user terminal demodulated at the relay, and the second SIR of the signal of the user terminal demodulated at the user terminal and the signal of the user terminal further away from the base station than itself; and select the relays corresponding to the data transmission rates greater than the minimum transmission rate as the candidate relays, thereby obtaining X candidate relays.

[0030] According to an embodiment of the present invention, when the determining module determines the target relay from X candidate relays based on the third signal-to-interference-plus-noise ratio (SIR) and its corresponding first and second SIRs, it is configured to: for each candidate relay, calculate the achievable transmission rate of the eavesdropped user terminal based on the first SIR and the second SIR of the signal of the eavesdropped user terminal demodulated at the candidate relay, and calculate the eavesdropping rate of the eavesdropper on the signal of the eavesdropped user terminal based on the third SIR of the signal of the eavesdropper demodulated at the eavesdropper, and calculate the secure transmission rate of the eavesdropped user terminal based on the achievable transmission rate and the eavesdropping rate; and select the candidate relay corresponding to the maximum secure transmission rate as the target relay.

[0031] Thirdly, embodiments of the present invention provide a chip device including a memory, a processor, and a computer program stored in the memory. When the computer program is executed by the processor, it implements the above-described data transmission method for a non-orthogonal multiple access network.

[0032] Fourthly, embodiments of the present invention propose a non-orthogonal multiple access network, which includes a base station, an eavesdropper, N relays and M user terminals. The base station, the user terminals and the eavesdropper operate in half-duplex mode, the relays operate in full-duplex mode and have energy harvesting function; the non-orthogonal multiple access network also includes the aforementioned chip device.

[0033] The non-orthogonal multiple access network and its data transmission method, apparatus and chip device of the present invention, for multiple relays with full-duplex and energy harvesting functions, and considering the impact of the relay power division factor on the correct demodulation of the signal, as well as the impact of eavesdropping on user terminals, selects the relay that can maximize the safe transmission rate of the eavesdropped user terminal for signal decoding and forwarding, which can effectively improve the energy utilization, bandwidth utilization and transmission reliability of the non-orthogonal multiple access network.

[0034] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a non-orthogonal multiple access network according to an embodiment of the present invention;

[0036] Figure 2 This is a flowchart of a data transmission method for a non-orthogonal multiple access network according to an embodiment of the present invention;

[0037] Figure 3 This is a flowchart of a data transmission method for a non-orthogonal multiple access network according to another embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram illustrating the reliability of different transmission schemes under different transmit signal-to-noise ratio conditions, as an example of the present invention.

[0039] Figure 5 This is a graph showing the relationship between the power division factor, residual self-interference, and security interruption probability in an example of the present invention.

[0040] Figure 6 This is a simulation flowchart of an example of the present invention;

[0041] Figure 7This is a structural block diagram of a data transmission device for a non-orthogonal multiple access network according to an embodiment of the present invention;

[0042] Figure 8 This is a structural block diagram of a chip device according to an embodiment of the present invention;

[0043] Figure 9 This is a structural block diagram of a non-orthogonal multiple access network according to an embodiment of the present invention. Detailed Implementation

[0044] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0045] In the context of non-orthogonal multiply access (NOMA) networks, this invention proposes a highly reliable relay transmission strategy to optimize the reliable transmission performance of NOMA networks in the presence of external eavesdroppers.

[0046] Specifically, this invention addresses the problem of efficient demodulation and reliable transmission of multiple relays with energy harvesting and full-duplex functionality in energy-constrained scenarios. With the increasing number of access devices (including user terminals, relays, etc.), higher demands are placed on the bandwidth and energy utilization of non-orthogonal multiple access networks (NOMA). Simultaneously, the presence of potential malicious nodes (such as eavesdroppers) compromises the quality of highly reliable communication transmission. Therefore, this invention combines the characteristics of energy harvesting (which effectively solves the problem of low energy utilization) and NOMA technology (which improves bandwidth utilization). To address the performance degradation caused by eavesdroppers, it proposes a highly reliable transmission strategy to improve the overall data reliability performance of the non-orthogonal multiple access network by maximizing the secure transmission rate of the eavesdropped user terminal.

[0047] The following description, with reference to the accompanying drawings, describes a non-orthogonal multiple access network and its data transmission method, apparatus, and chip device according to embodiments of the present invention.

[0048] In embodiments of the present invention, such as Figure 1 As shown, a non-orthogonal multiple access network includes a base station BS, an eavesdropper EV, and N relays R (denoted as R1, R2, ..., R1). N M user terminals (UEs) (denoted as U1, U2, ..., U...) N Among them, the base station, user terminal and eavesdropper operate in half-duplex mode, while the relay operates in full-duplex mode and has energy harvesting function.

[0049] Specifically, the BS (Base Station) acts as a fixed base station and signal source, generating a non-orthogonal multiple access signal through superposition coding and sending it to N relays. User terminals obtain communication data through relay forwarding, while eavesdroppers can only eavesdrop on the data forwarded to user terminals by the relays. All N relays employ Simultaneous Wireless Information and Power Transfer (SWIPT) technology, using power division to harvest energy from the β (representing the relay's power division factor) portion of the received signal (e.g., radio frequency signal), and using the remaining 1-β portion for signal decoding. The harvested energy is then used to forward the decoded signal. Considering obstacles and deep fading between the base station and user terminals, all user terminals require relay forwarding to maintain normal communication, and eavesdroppers can only eavesdrop on signals from relay forwarding. In the entire network, only the relay has two antennas, operates in full-duplex (FD) mode, and is an energy-constrained device; all other devices have a single antenna and operate in half-duplex mode. The decoding of all relays and user terminals follows the Successive Interference Cancellation (SIC) decoding principle.

[0050] Figure 2 This is a flowchart of a data transmission method for a non-orthogonal multiple access network according to an embodiment of the present invention.

[0051] like Figure 2 As shown, the data transmission methods in non-orthogonal multiple access networks include:

[0052] S101, obtain the power division factor of the relay and the power allocation factor of each user terminal.

[0053] The power allocation factor for each user terminal can be set by the base station based on the distance between each user terminal and the base station.

[0054] Specifically, such as Figure 3 As shown, in a non-orthogonal multiple access network, the base station first performs initialization work when transmitting data. Initialization work includes: setting the power allocation factor for each user terminal based on its distance from the base station; and simultaneously setting the power division factor for relays.

[0055] S102, the base station superimposes and encodes the signals of each user terminal, generates and transmits the superimposed signal, and calculates the first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each relay, the second SIR of the demodulated signal at each user terminal, and the third SIR of the demodulated signal at the eavesdropper, respectively, based on the power division factor and the power allocation factor.

[0056] Specifically, see Figure 3 After initialization, the base station superimposes and encodes the signals from each user terminal to generate a superimposed signal, which is then transmitted. This is followed by the relay selection phase. During the selection phase, the signal-to-interference-plus-noise ratio (SIR) of the decoded signals at each relay, each user terminal, and the eavesdropper is calculated to aid in subsequent relay selection. The superimposed signal is a non-orthogonal multiple access (NMO) signal.

[0057] In this embodiment, the signal-to-interference-plus-noise ratio (SIR) of the decoded signal at the eavesdropper's location can be calculated when selecting any relay for data forwarding; alternatively, a first SIR and a second SIR can be calculated first, and a relay selection can be performed based on the first and second SIRs (e.g., selecting based on meeting the minimum transmission rate of each user terminal), and then a third SIR can be calculated based on the selected relay. Obviously, the latter involves less computation than the former.

[0058] S103, based on the first signal-to-interference-plus-noise ratio, the second signal-to-interference-plus-noise ratio and the third signal-to-interference-plus-noise ratio, determine the target relay from the N relays, wherein the target relay is the relay that enables the eavesdropped user terminal to have the maximum secure transmission rate.

[0059] Specifically, based on the first signal-to-interference-plus-noise ratio (SIR), the second SIR, and the third SIR, the secure transmission rate of the eavesdropped user terminal (such as the user terminal closest to the base station) when each relay forwards data can be calculated. Then, the relay corresponding to the maximum secure transmission rate can be selected as the target relay to improve the secure data transmission performance.

[0060] S104 performs energy harvesting and decoding processing on the superimposed signal through the target relay and forwards it to each user terminal.

[0061] Specifically, such as Figure 3 As shown, after selecting the target relay, the superimposed signal is subjected to energy harvesting and decoding processing through the target relay, and then the processed signal is forwarded to each user terminal, which can improve the secure transmission performance of data.

[0062] This data transmission method for non-orthogonal multiple access networks targets multiple relays with full-duplex and energy harvesting capabilities. It considers the impact of relay power division factors on correct signal demodulation and the potential for eavesdropping on user terminals. By selecting the relay that maximizes the secure transmission rate of the eavesdropped user terminal for signal decoding and forwarding, it can effectively improve the energy utilization, bandwidth utilization, and transmission reliability of non-orthogonal multiple access networks.

[0063] In some embodiments of the present invention, determining a target relay from N relays based on a first signal-to-interference-plus-noise ratio (SINR), a second SINR, and a third SINR includes: determining X candidate relays from the N relays based on the first SINR and the second SINR, wherein the candidate relays are relays that enable each user terminal to meet the minimum transmission rate requirement, and the third SINR is the SINR of the demodulated signal at the eavesdropper calculated when each candidate relay forwards data; and determining the target relay from the X candidate relays based on the first SINR, the second SINR, and the third SINR.

[0064] Specifically, such as Figure 3 As shown, when determining the target relay, X candidate relays can be selected from N relays based on the first and second signal-to-interference-plus-noise ratios (SNRs), forming a relay subset Nr to meet the minimum transmission requirements of all user terminals. Based on the X candidate relays and the eavesdropped user terminals, a third SNR is calculated, with the corresponding first and second SNRs also based on the X candidate relays and the eavesdropped user terminals. The target relay is then determined from the X candidate relays based on the third SNR and its corresponding first and second SNRs, thus optimizing data transmission performance.

[0065] It should be noted that, as Figure 3 As shown, when the relay subset Nr is an empty set If this occurs, it indicates that there is no relay in the current non-orthogonal multiple access network that can meet the minimum transmission requirements of all user terminals, and the current optimization process can be terminated.

[0066] In some embodiments of the present invention, the data transmission method for a non-orthogonal multiple access network further includes: acquiring residual self-interference of relays; and calculating, based on power division factor, power allocation factor, and residual self-interference, a first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each relay, a second SIR of the demodulated signal at each user terminal, and a third SIR of the demodulated signal at the eavesdropper.

[0067] With the increasing availability of relay functions (including full-duplex and energy harvesting functions), residual self-interference (RSI) also affects the correct demodulation of signals. To address this, this invention proposes a reliable transmission scheme for cooperative NOMA networks that comprehensively considers power division factor and residual self-interference, in order to further improve the energy utilization, bandwidth utilization and transmission reliability of communication systems.

[0068] In some embodiments of the present invention, determining X candidate relays from N relays based on a first signal-to-interference-plus-noise ratio (SINR) and a second SINR includes: for each relay, calculating the data transmission rate corresponding to the relay based on the first SINR of the signal demodulated at each user terminal at the relay, and the second SINR of the signal demodulated at each user terminal at itself and the signal of user terminals farther from the base station than itself; and selecting relays with data transmission rates greater than the corresponding minimum transmission rate as candidate relays to obtain X candidate relays.

[0069] Specifically, according to their distance from the base station, user terminal 1 is defined as the farthest user, and user terminal M is defined as the nearest user, that is, the distance between user terminal 1, user terminal 2, ..., user terminal M and the base station decreases in sequence.

[0070] The first signal-to-interference-plus-noise ratio can be calculated using the following formula:

[0071]

[0072] in, α represents the first signal-to-interference-plus-noise ratio (SIR) of the signal demodulated at user terminal j at the i-th relay. j α represents the power allocation factor for user terminal j. k p represents the power allocation factor for user terminal k. s β represents the transmit signal-to-noise ratio of the base station, and β represents the power division factor. Let denot represent the channel gain from the base station to the i-th relay, δ represent the residual self-interference factor of the i-th relay, η represent the energy collection efficiency of the relay, and M represent the total number of user terminals.

[0073] The second signal-to-interference-plus-noise ratio can be calculated using the following formula:

[0074]

[0075] in, This represents the second signal-to-interference-plus-noise ratio (SIR) of the signal from user terminal k demodulated at user terminal j when the i-th relay forwards data. Let m represent the distance between the i-th relay and the user terminal j, and m represent the path loss factor. Indicates distance power of m Let represent the channel gain from the i-th relay to the user terminal j.

[0076] After obtaining the first signal-to-interference-plus-noise ratio (SIR) and the second SIR, X candidate relays can be determined from N relays using the following formula:

[0077]

[0078] Where, N rLet X be the set of X candidate relays. This represents the data transmission rate corresponding to the i-th relay. This represents the minimum transmission rate of user terminal j. X is an unknown quantity, which can be empty or any value greater than or equal to 1 and less than or equal to N.

[0079] In some embodiments of the present invention, determining a target relay from X candidate relays based on a first signal-to-interference-plus-noise ratio (SIR), a second SIR, and a third SIR includes: for each candidate relay, calculating the achievable transmission rate of the eavesdropped user terminal based on the first SIR of the signal demodulated at the candidate relay and the second SIR of the signal demodulated at the eavesdropped user terminal; calculating the eavesdropping rate of the eavesdropper on the signal of the eavesdropped user terminal based on the third SIR of the signal demodulated at the eavesdropper; and calculating the secure transmission rate of the eavesdropped user terminal based on the achievable transmission rate and the eavesdropping rate; and selecting the candidate relay corresponding to the maximum secure transmission rate as the target relay.

[0080] Specifically, the third signal-to-interference-plus-noise ratio (SIR) can be calculated using the following formula:

[0081]

[0082] in, α represents the third signal-to-interference-plus-noise ratio (SNR) of the signal from user terminal k demodulated at the eavesdropper's location when the i-th relay forwards data. k This represents the power allocation factor for user terminal k. Let represent the channel gain from the i-th relay to the eavesdropper.

[0083] If the user terminal being eavesdropped on is the user terminal M closest to the base station, the target relay can be obtained using the following formula:

[0084]

[0085] Among them, i * Indicates the target relay. This represents the achievable transmission rate of user terminal M when the i-th candidate relay performs data forwarding; This represents the rate at which the eavesdropper intercepts the signal of user terminal M when the i-th candidate relay is forwarding data. This represents the secure transmission rate of user terminal M when the i-th candidate relay performs data forwarding.

[0086] In some embodiments of the present invention, the secure transmission rate of user terminal M can be defined as:

[0087]

[0088] in, Equation (6) indicates that the secure transmission rate must be greater than 0. If the value is negative or 0, the corresponding relay can be discarded directly when determining the target relay.

[0089] Based on equation (5), it can be seen that the relay selection process is closely related to the end-to-end signal-interference-noise ratio (SINR) from the source (i.e., base station) to the relay, from the relay to user M, and from the relay to the eavesdropper. Based on equations (1), (2), and (4), it can be seen that the end-to-end SINR between nodes is closely related to the power division factor β and the residual self-interference ζ. Therefore, this invention comprehensively considers the impact of the power division factor and residual self-interference on transmission performance, and takes into account the presence of external eavesdroppers. It proposes a relay transmission strategy that aims to maximize the secure transmission rate of the user terminal closest to the base station while meeting the minimum transmission rate of all user terminals, which can improve the reliable data transmission performance.

[0090] It should be noted that the above equations (1)(2)(4) adopt the power-division-based energy harvesting method, and the time-division-based energy harvesting method can also be adopted; some conditions in equations (1)(2)(4) can also be weakened, such as setting the self-interference channel to be a non-fading channel, so as to optimize the reliability of transmission to a certain extent while reducing the computational complexity of the solution process.

[0091] To verify the data transmission performance of the proposed solution, the solution is compared and analyzed with other relay transmission solutions, and the results are demonstrated through simulation. The comparative analysis is as follows:

[0092] The transmission scheme based on Random Relay Selection (RRS) does not require knowledge of the end-to-end channel state of any node, greatly saving overhead. However, since a relay is randomly selected for transmission each time, and there are no selection rules, this transmission scheme has the worst performance.

[0093] Partial Relay Selection (PRS) based transmission schemes: This approach does not require knowledge of the end-to-end channel states of all nodes, thus saving some overhead. Assuming only the channel states from the base station (BS) to each relay are known, the relay with the best channel state is selected as the optimal relay i by comparison. * This can improve transmission reliability to some extent. The selection rules follow these guidelines:

[0094]

[0095] The transmission scheme based on Optimal Relay Selection (ORS) (i.e., the transmission scheme proposed in this invention) requires the network to know the end-to-end channel state of all nodes, so the network overhead is the largest compared to the previous two schemes; however, this strategy can achieve highly reliable transmission of the entire communication at the cost of increased overhead.

[0096] Figure 4 Simulation results show the impact of base station transmit signal-to-noise ratio (SNR) on the security performance of different transmission schemes under varying numbers of relays. It can be seen that when the transmit SNR is below 35 dB, the performance of the proposed ORS scheme is superior to both the RRS and PRS schemes, indicating that ORS has the optimal reliable transmission performance, consistent with the above analysis results. Furthermore, increasing the number of relays can also improve transmission performance. When the transmit SNR is greater than 35 dB, transmission performance deteriorates because a higher transmit SNR leads to significant residual self-interference at the relays, thus worsening the demodulation at the relays.

[0097] To illustrate the impact of power division factor and residual self-interference on reliable transmission Figure 5 Simulation results are shown illustrating the relationship between the power segmentation factor β, residual self-interference δ, and security outage probability under different transmit signal-to-noise ratios (SNRs) for the proposed scheme. It can be seen that as β increases, the security outage probability reaches a minimum, at which point the reliable transmission performance is optimal. This is because there exists an optimal solution for the energy segmentation ratio between energy harvesting and signal processing, under which the most reliable transmission performance is achieved. Simultaneously, when δ = 5 × 10... -5 At this point, increasing the transmit signal-to-noise ratio from 20dB to 30dB did not improve performance. This is because an excessively high transmit signal-to-noise ratio at this level would cause residual self-interference to become the main cause of performance degradation. In contrast, reducing δ to 5×10... -6 It can be observed that when the transmit signal-to-noise ratio is also equal to 30dB, lower residual self-interference results in better performance. Therefore, a higher transmit signal-to-noise ratio does not necessarily mean more reliable transmission performance; the most suitable transmit power value should be selected based on the power division factor and residual self-interference.

[0098] The above simulation was implemented using MATLAB. In the simulation, it was assumed that all channel gains were independent and identically distributed complex Gaussian variables with zero mean and unit variance, while noise was an independent and identically distributed Gaussian variable with zero mean and unit variance. Only the distance between user terminals and the base station was considered; the distances between other nodes were ignored. Based on the distances, it was assumed that the distance from user terminal 1 to base station BS was 1 unit, and the distance from user terminal M to base station BS was 0.5 units. The remaining user terminals were uniformly distributed within the interval, and the path loss factor m = 2.7. Small-scale fading was considered for the channels between the remaining nodes. The energy collection efficiency η = 0.9, the power allocation factors for the two user terminals were set to 0.7 and 0.3 respectively, and the corresponding transmission rate thresholds (i.e., the minimum transmission rate mentioned above) were 0.3 and 0.6 respectively. The safe rate threshold was set to 0.1. The transmit signal-to-noise ratio and power division factor were set as independent variables, with values ​​ranging from [-5dB, 45dB] and (0,1) respectively.

[0099] Since it is assumed that the distribution of all channel gains follows a complex Gaussian distribution, the channel gains therefore follow an exponential distribution. For example... Figure 6 As shown, assuming the number of loops is set to K, K random numbers following an exponential distribution need to be generated. After obtaining the random numbers, the K values ​​of the demodulated transmit signal-to-noise ratio (SNR) for a single node can be obtained. Knowing the SNR values, the transmission rate can be calculated using Shannon's formula and compared with the user terminal's transmission rate threshold to determine if the transmission was successful. If successful, the cumulative success count is incremented by 1. After the loop ends, the reliability of the communication transmission is measured by calculating the cumulative success count L / K, which yields the probability of a secure interruption.

[0100] Figure 7 This is a structural block diagram of a data transmission device for a non-orthogonal multiple access network according to an embodiment of the present invention.

[0101] like Figure 7 As shown, the data transmission device 100 of the non-orthogonal multiple access network includes: an acquisition module 110, a calculation module 120, a determination module 130, and a transmission module 140.

[0102] In this embodiment, the acquisition module 110 is used to acquire the power division factor of the relay and the power allocation factor of each user terminal; the calculation module 120 is used by the base station to superimpose and encode the signals of each user terminal, generate and transmit the superimposed signal, and calculate the first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each relay, the second SIR of the demodulated signal at each user terminal, and the third SIR of the demodulated signal at the eavesdropper according to the power division factor and the power allocation factor; the determination module 130 is used to determine the target relay from N relays according to the first SIR, the second SIR, and the third SIR, wherein the target relay is the relay that enables the eavesdropped user terminal to have the maximum secure transmission rate; the transmission module 140 is used to perform energy harvesting and decoding processing on the superimposed signal through the target relay and forward it to each user terminal.

[0103] In some embodiments of the present invention, when determining a target relay from N relays based on a first signal-to-interference-plus-noise ratio (SINR), a second SINR, and a third SINR, the determining module 130 is configured to: determine X candidate relays from the N relays based on the first SINR and the second SINR, wherein the candidate relays are relays that enable each user terminal to meet the minimum transmission rate requirement, and the third SINR is the SINR of the demodulated signal at the eavesdropper calculated when each candidate relay performs data forwarding; and determine the target relay from the X candidate relays based on the first SINR, the second SINR, and the third SINR.

[0104] In some embodiments of the present invention, the acquisition module 110 is further configured to acquire the residual self-interference of the relay; the calculation module 120 is further configured to calculate the first signal-to-interference-plus-noise ratio (SNR) of the demodulated signal at each relay, the second SNR of the demodulated signal at each user terminal, and the third SNR of the demodulated signal at the eavesdropper, respectively, based on the power division factor, the power allocation factor, and the residual self-interference.

[0105] In some embodiments of the present invention, when determining X candidate relays from N relays based on a first signal-to-interference-plus-noise ratio (SINR) and a second SINR, the determining module 130 is configured to: for each relay, calculate the data transmission rate corresponding to the relay based on the first SINR of the signal demodulated at each user terminal at the relay, and the second SINR of the signal demodulated at each user terminal at itself and the signal of user terminals farther from the base station than itself; and select the relays corresponding to the data transmission rates greater than the minimum transmission rate as candidate relays to obtain X candidate relays.

[0106] In some embodiments of the present invention, when determining a target relay from X candidate relays based on a first signal-to-interference-plus-noise ratio (SIR), a second SIR, and a third SIR, the determining module 130 is configured to: for each candidate relay, calculate the achievable transmission rate of the eavesdropped user terminal based on the first SIR of the signal demodulated at the candidate relay and the second SIR of the signal demodulated at the eavesdropped user terminal; calculate the eavesdropping rate of the eavesdropper on the signal of the eavesdropped user terminal based on the third SIR of the signal demodulated at the eavesdropper; and calculate the secure transmission rate of the eavesdropped user terminal based on the achievable transmission rate and the eavesdropping rate; and select the candidate relay corresponding to the maximum secure transmission rate as the target relay.

[0107] It should be noted that for other specific embodiments of the data transmission device of the non-orthogonal multiple access network of the present invention, please refer to the specific embodiments of the data transmission method of the non-orthogonal multiple access network of the present invention as described above.

[0108] Figure 8 This is a structural block diagram of a chip device according to an embodiment of the present invention.

[0109] like Figure 8 As shown, the chip device 500 includes a processor 501 and a memory 503. The processor 501 and the memory 503 are connected, for example, via a bus 502. Optionally, the chip device 500 may also include a transceiver 504. It should be noted that in practical applications, the transceiver 504 is not limited to one type, and the structure of this chip device 500 does not constitute a limitation on the embodiments of the present invention.

[0110] Processor 501 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this invention. Processor 501 may also be a combination that implements computational functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0111] Bus 502 may include a pathway for transmitting information between the aforementioned components. Bus 502 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. Bus 502 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 8 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0112] The memory 503 stores a computer program corresponding to the data transmission method of the non-orthogonal multiple access network in the above embodiments of the present invention. This computer program is executed under the control of the processor 501. The processor 501 executes the computer program stored in the memory 503 to implement the content shown in the aforementioned method embodiments.

[0113] Among them, the chip devices 500 include, but are not limited to: mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), and PMPs (portable multimedia players), as well as fixed terminals such as digital TVs and desktop computers. Figure 5 The chip device 500 shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0114] Figure 9 This is a block diagram of a non-orthogonal multiple access network according to an embodiment of the present invention.

[0115] like Figure 9 As shown, the non-orthogonal multiple access network 900 includes a base station BS, an eavesdropper EV, N relays R and M user terminals UE, as well as the chip device 500 of the above embodiment.

[0116] Among them, the base station (BS), user terminal (UE), and eavesdropper (EV) operate in half-duplex mode, while the relay (R) operates in full-duplex mode and has energy harvesting capabilities.

[0117] In embodiments of the present invention, the chip device 500 may be integrated into a base station BS, or into one or more relays R, or may be set up separately.

[0118] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0119] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0120] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0121] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0122] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0123] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0124] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0125] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A data transmission method for a non-orthogonal multiple access network, characterized in that, The non-orthogonal multiple access network includes a base station, an eavesdropper, N relays, and M user terminals. The base station, the user terminals, and the eavesdropper operate in half-duplex mode, while the relays operate in full-duplex mode and have energy harvesting capabilities. The method includes: Obtain the power division factor of the relay and the power allocation factor of each user terminal; The base station performs superposition encoding on the signals of each user terminal, generates and transmits the superposition signal, and calculates the first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each relay, the second SIR of the demodulated signal at each user terminal, and the third SIR of the demodulated signal at the eavesdropper, respectively, based on the power division factor and the power allocation factor. Based on the first signal-to-interference-plus-noise ratio (SIR), the second SIR, and the third SIR, a target relay is determined from the N relays, wherein the target relay is the relay that enables the eavesdropped user terminal to have the maximum secure transmission rate; The superimposed signal is processed by the target relay for energy harvesting and decoding, and then forwarded to each of the user terminals. The step of determining the target relay from the N relays based on the first signal-to-interference-plus-noise ratio (SIR), the second SIR, and the third SIR includes: Based on the first signal-to-interference-plus-noise ratio (SIR) and the second SIR, X candidate relays are determined from the N relays, wherein the candidate relays are relays that enable each user terminal to meet the minimum transmission rate requirement, and the third SIR is the SIR calculated by each candidate relay when forwarding data, which is the SIR of the signal of the eavesdropped user terminal demodulated at the eavesdropper; based on the third SIR and its corresponding first SIR and second SIR, the target relay is determined from the X candidate relays.

2. The data transmission method for a non-orthogonal multiple access network according to claim 1, characterized in that, The method further includes: Obtain the residual self-interference of the relay; Based on the power division factor, the power allocation factor, and the residual self-interference, the first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each of the relay stations, the second SIR of the demodulated signal at each of the user terminals, and the third SIR of the demodulated signal at the eavesdropper are calculated respectively.

3. The data transmission method for a non-orthogonal multiple access network according to claim 2, characterized in that, The step of determining X candidate relays from N relays based on the first signal-to-interference-plus-noise ratio (SIR) and the second SIR includes: For each relay, the data transmission rate corresponding to the relay is calculated based on a first signal-to-interference-plus-noise ratio (SIR) of the signal of each user terminal demodulated at the relay, and a second SIR of the signal of the user terminal itself and the signal of a user terminal farther away from the base station at each user terminal. The relays with data transmission rates greater than the corresponding minimum transmission rate are selected as candidate relays, resulting in X candidate relays.

4. The data transmission method for a non-orthogonal multiple access network according to claim 3, characterized in that, The step of determining the target relay from X candidate relays based on the third signal-to-interference-plus-noise ratio (SIR) and its corresponding first and second SIRs includes: For each candidate relay, the achievable transmission rate of the eavesdropped user terminal is calculated based on a first signal-to-interference-plus-noise ratio (SNR) of the signal of the eavesdropped user terminal demodulated at the candidate relay and a second SNR of the signal of the eavesdropped user terminal demodulated at the eavesdropper. The eavesdropping rate of the eavesdropper on the signal of the eavesdropped user terminal is calculated based on a third SNR of the signal of the eavesdropper demodulated at the eavesdropper. The secure transmission rate of the eavesdropped user terminal is calculated based on the achievable transmission rate and the eavesdropping rate. The candidate relay corresponding to the maximum secure transmission rate is selected as the target relay.

5. The data transmission method for a non-orthogonal multiple access network according to claim 4, characterized in that, The first signal-to-interference-plus-noise ratio is calculated using the following formula: in, This represents the first signal-to-interference-plus-noise ratio (SIR) of the signal demodulated at user terminal j at the i-th relay. This represents the power allocation factor for user terminal j. This represents the power allocation factor for user terminal k. β represents the transmit signal-to-noise ratio of the base station, and β represents the power division factor. This represents the channel gain from the base station to the i-th relay. This represents the residual self-interference factor of the i-th relay. The relay's energy efficiency is represented by M, where M is the total number of user terminals.

6. The data transmission method for a non-orthogonal multiple access network according to claim 5, characterized in that, The second signal-to-interference-plus-noise ratio is calculated using the following formula: in, This represents the second signal-to-interference-plus-noise ratio (SIR) of the signal from user terminal k demodulated at user terminal j when the i-th relay forwards data. Let m represent the distance between the i-th relay and the user terminal j, and m represent the path loss factor. Indicates distance power of m Let represent the channel gain from the i-th relay to the user terminal j.

7. The data transmission method for a non-orthogonal multiple access network according to claim 6, characterized in that, The distances between user terminal 1, user terminal 2, ..., user terminal M and the base station decrease sequentially. X candidate relays are determined from the N relays using the following formula: in, This represents the set consisting of X candidate relays. This represents the data transmission rate corresponding to the i-th relay. This represents the minimum transmission rate of user terminal j.

8. The data transmission method for a non-orthogonal multiple access network according to claim 6, characterized in that, The third signal-to-interference-plus-noise ratio is calculated using the following formula: in, This represents the third signal-to-interference-plus-noise ratio (SIR) of the signal from user terminal k demodulated at the eavesdropper's location when the i-th relay forwards data. This represents the power allocation factor for user terminal k. Let represent the channel gain from the i-th relay to the eavesdropper.

9. The data transmission method for a non-orthogonal multiple access network according to claim 8, characterized in that, The eavesdropped user terminal is the user terminal M closest to the base station, and the target relay is obtained by the following formula: in, Indicates the target relay, This represents the achievable transmission rate of user terminal M when the i-th candidate relay performs data forwarding; This represents the rate at which the eavesdropper intercepts the signal of the user terminal M when the i-th candidate relay forwards data. This represents the secure transmission rate of the user terminal M when the i-th candidate relay performs data forwarding.

10. A data transmission apparatus for a non-orthogonal multiple access network, characterized in that, The non-orthogonal multiple access network includes a base station, an eavesdropper, N relays, and M user terminals. The base station, the user terminals, and the eavesdropper operate in half-duplex mode, while the relays operate in full-duplex mode and have energy harvesting capabilities. The device includes: An acquisition module is used to acquire the power division factor of the relay and the power allocation factor of each user terminal; The calculation module is used to superimpose and encode the signals of each user terminal by the base station, generate and transmit the superimposed signal, and then calculate the first signal-to-interference-plus-noise ratio (SIR) of the demodulated signal at each relay, the second SIR of the demodulated signal at each user terminal and the third SIR of the demodulated signal at the eavesdropper according to the power division factor and the power allocation factor. The determining module is used to determine a target relay from N relays based on the first signal-to-interference-plus-noise ratio, the second signal-to-interference-plus-noise ratio, and the third signal-to-interference-plus-noise ratio, wherein the target relay is the relay that enables the eavesdropped user terminal to have the maximum secure transmission rate; The transmitting module is used to perform energy harvesting and decoding processing on the superimposed signal through the target relay, and forward it to each of the user terminals; When the determining module determines a target relay from N relays based on the first signal-to-interference-plus-noise ratio (SIR), the second SIR, and the third SIR, it is used to: Based on the first signal-to-interference-plus-noise ratio (SIR) and the second SIR, X candidate relays are determined from the N relays, wherein the candidate relays are relays that enable each user terminal to meet the minimum transmission rate requirement, and the third SIR is the SIR calculated by each candidate relay when forwarding data, which is the SIR of the signal of the eavesdropped user terminal demodulated at the eavesdropper; based on the third SIR and its corresponding first SIR and second SIR, the target relay is determined from the X candidate relays.

11. The data transmission apparatus for a non-orthogonal multiple access network according to claim 10, characterized in that, The acquisition module is also used to acquire the residual self-interference of the relay; The calculation module is further configured to calculate, based on the power division factor, the power allocation factor, and the residual self-interference, the first signal-to-interference-plus-noise ratio (SNR) of the demodulated signal at each of the relays, the second SNR of the demodulated signal at each of the user terminals, and the third SNR of the demodulated signal at the eavesdropper.

12. The data transmission apparatus for a non-orthogonal multiple access network according to claim 11, characterized in that, When the determining module determines X candidate relays from the N relays based on the first signal-to-interference-plus-noise ratio (SIR) and the second SIR, it is used to: For each relay, the data transmission rate corresponding to the relay is calculated based on a first signal-to-interference-plus-noise ratio (SIR) of the signal of each user terminal demodulated at the relay, and a second SIR of the signal of the user terminal itself and the signal of a user terminal farther away from the base station at each user terminal. The relays with data transmission rates greater than the minimum transmission rate are selected as candidate relays, resulting in X candidate relays.

13. The data transmission apparatus for a non-orthogonal multiple access network according to claim 12, characterized in that, When the determining module determines the target relay from X candidate relays based on the third signal-to-interference-plus-noise ratio (SIR) and its corresponding first and second SIRs, it is used to: For each candidate relay, the achievable transmission rate of the eavesdropped user terminal is calculated based on a first signal-to-interference-plus-noise ratio (SNR) of the signal of the eavesdropped user terminal demodulated at the candidate relay and a second SNR of the signal of the eavesdropped user terminal demodulated at the eavesdropper. The eavesdropping rate of the eavesdropper on the signal of the eavesdropped user terminal is calculated based on a third SNR of the signal of the eavesdropper demodulated at the eavesdropper. The secure transmission rate of the eavesdropped user terminal is calculated based on the achievable transmission rate and the eavesdropping rate. The candidate relay corresponding to the maximum secure transmission rate is selected as the target relay.

14. A chip device comprising a memory, a processor, and a computer program stored on the memory, characterized in that, When the computer program is executed by the processor, it implements the data transmission method for a non-orthogonal multiple access network as described in any one of claims 1-9.

15. A non-orthogonal multiple access network, characterized in that, The non-orthogonal multiple access network includes a base station, an eavesdropper, N relays and M user terminals. The base station, the user terminals and the eavesdropper operate in half-duplex mode, and the relays operate in full-duplex mode and have energy harvesting capabilities. The non-orthogonal multiple access network further includes the chip device as described in claim 14.

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