Full duplex relay transmission method based on rate division multiple access

Abstract

The invention discloses a full duplex relay transmission method based on rate division multiple access. The method comprises the following steps: dividing an information transmission process into a first time slot and a second time slot; in a first time slot, the relay user communicates with two edge users by using downlink RSMA; meanwhile, the two edge users send information to be exchanged by themselves to the relay user by using uplink RSMA; in a second time slot, the relay user decodes and forwards the uplink RSMA signal received in the first time slot to realize information exchange of the two edge users; meanwhile, the two edge users continue to use the uplink RSMA to communicate with the relay user; wherein when the first edge user sends the information by using the uplink RSMA, the information of the first edge user is divided into two parts to be sent, and the information of the second edge user is directly sent out. According to the invention, uplink and downlink RSMA transmission can be combined, the communication coverage range is expanded, and the system spectrum efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a full-duplex relay transmission method based on rate division multiple access. Background Art

[0002] With the rapid development of smart cities, industrial automation, and autonomous driving, the number of communication terminals has increased dramatically, which has put forward higher requirements for the new generation of mobile networks in terms of user data rate, spectrum efficiency, communication coverage, etc. As one of the candidates for the next generation of multiple access technology, rate division multiple access technology has shown great potential in improving spectrum utilization and enhancing communication stability.

[0003] Rate division multiple access technology decomposes user information into public and private parts and allocates power reasonably, so that some interference can be decoded and some interference can be treated as noise, thereby improving the system's service quality and spectrum efficiency. Introducing cooperative relay technology in wireless systems can effectively improve the throughput of users at the edge of the cell and improve their service quality, while expanding the communication coverage. As an important branch of cooperative relay, two-way relay technology can exchange information between a pair of users. Compared with the traditional one-way relay method, two-way relay can improve the efficiency of spectrum utilization, thereby achieving more efficient communication performance. In order to further improve system performance, a communication scheme using full-duplex mode has been proposed. Full-duplex communication allows nodes to receive and forward information at the same time, which can significantly improve spectrum efficiency and network throughput.

[0004] However, existing joint uplink and downlink schemes have a common feature: they need to complete uplink and downlink transmission tasks in time-sharing, that is, they are all unidirectional transmissions in the same time slot, and two-way information transmission can only be completed through multiple time slots, which will cause potential spectrum efficiency loss. Secondly, in addition to the above-mentioned spectrum loss problem, the existing joint uplink and downlink schemes based on non-orthogonal multiple access (NOMA) also lack flexible interference management capabilities because they transmit complete user signals rather than flexibly segmented signals.

[0005] Therefore, studying the full-duplex relay transmission method based on rate division multiple access is of great significance for improving the performance of mobile networks and meeting the growing demands of user data rate, spectrum efficiency and communication coverage. Summary of the invention

[0006] The purpose of the present invention is to provide a full-duplex relay transmission method based on rate division multiple access, and propose a new type of simultaneous direct transmission and cooperative two-way RSMA communication strategy, which uses two time slots to complete two-way information exchange, and each time slot can support two-way information transmission, thereby improving spectrum efficiency, and by setting the ratio parameters of public streams and private streams and the power allocation coefficient, it is achieved that part of the interference can be decoded and part of the interference is treated as noise, so as to flexibly manage interference, meet the increasing user data rate, expand the communication coverage, and improve the system spectrum efficiency.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: The present invention discloses a full-duplex relay transmission method based on rate division multiple access, the method comprising the following steps: A three-user bidirectional relay system model based on rate division multiple access is set up, which includes a relay user, a first edge user and a second edge user, and is a time division duplex system with channel reciprocity; the information transmission process follows the bidirectional RSMA communication strategy of simultaneous direct transmission and cooperation, and is divided into two time slots; In the first time slot, the relay user communicates with the two edge users using downlink RSMA; at the same time, the two edge users send the information they want to exchange to the relay user using uplink RSMA; In the second time slot, the relay user decodes and forwards the uplink RSMA signal received in the first time slot to implement information exchange between the two edge users; at the same time, the two edge users continue to communicate with the relay user using the uplink RSMA; Among them, when the first edge user uses the uplink RSMA to send information, it splits its own information into two parts, superimposes the encoding and forwards it, while the second edge user directly sends its own information.

[0008] Furthermore, the first time slot and the second time slot are equal in duration.

[0009] Furthermore, in the first time slot and the second time slot, the relay user uses a serial interference cancellation algorithm to sequentially decode the first part of the information split from the first edge user, the information of the second edge user, and the second part of the information split from the first edge user.

[0010] Furthermore, in the first time slot, the relay user uses downlink RSMA to broadcast a power domain superposition coded signal containing information required by two edge users; in the second time slot, the relay user decodes the information to be exchanged received in the first time slot and forwards it to the two edge users.

[0011] Furthermore, in the second time slot, the relay user decodes the information of the edge user received in the first time slot and superimposes it using physical layer network coding, and then broadcasts it; the edge user eliminates the signal component emitted by its own first time slot from the received signal based on the prior information of the signal emitted by its own first time slot, and directly decodes the signal emitted by another edge user in the first time slot.

[0012] Furthermore, according to the downlink RSMA principle, the relay user divides the information required by the first edge user into the public stream required by the first edge user and the private stream required by the first edge user; at the same time, the relay user divides the information required by the second edge user into the public stream required by the second edge user and the private stream required by the second edge user; then, the relay user synthesizes the public stream required by the first edge user and the public stream required by the second edge user into a public stream, and superimposes the encoding and forwarding it together with the other two private streams.

[0013] Furthermore, in the first time slot, according to the downlink RSMA principle, the two edge users use a serial interference cancellation algorithm to sequentially decode the public stream and the private streams they need.

[0014] Furthermore, in the first time slot and the second time slot, following the uplink RSMA principle, the specific splitting principle is to divide the first edge user into two virtual users, and then split the information of the first edge user into two parts and map them to the two virtual users respectively, and then the two virtual users send their own information.

[0015] Furthermore, the relay user and the two edge users all operate in full-duplex mode.

[0016] Compared with the prior art, the present invention has the following beneficial effects: First, the full-duplex relay transmission method based on rate division multiple access of the present invention is simultaneously bidirectional, that is, each time slot supports bidirectional information transmission, and has both direct transmission links and collaborative links, which can transmit more data signals and thus improve spectrum efficiency. Interference can also be flexibly managed by setting the ratio parameters of public and private flows and the power allocation coefficient.

[0017] Second, the full-duplex relay transmission method based on rate division multiple access of the present invention realizes the information exchange between all users through a new type of simultaneous direct transmission and cooperative two-way RSMA communication strategy, and expands the communication coverage. Specifically, while the users at both ends complete the information exchange with each other through the relay user, the relay user also completes the information exchange corresponding to the users at both ends by using RSMA.

[0018] Third, the full-duplex relay transmission method based on rate division multiple access of the present invention does not rely on fixed infrastructure (such as base stations) and can achieve corresponding functions by relying on three mobile users. It is not only applicable to cellular networks, but also can be applied to self-organizing networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a brief flow chart of a full-duplex relay transmission method based on rate division multiple access (RSMA) provided by the present invention; Figure 2 It is a schematic diagram of the transmission lines of the first time slot and the second time slot of the bidirectional RSMA communication strategy of simultaneous direct transmission and collaboration described in the embodiment; Figure 3 is a curve diagram of system traversal and capacity changes with transmission signal-to-noise ratio for different transmission methods described in Example 1, where both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) use full-duplex; Figure 4 It is a curve diagram of system traversal and capacity of different transmission methods described in Example 2 as a function of channel power between the relay user and the first edge user, where both OMA and NOMA use full duplex; Figure 5 This is a curve chart showing the change in system traversal and capacity of different transmission methods described in Example 2 as the channel power between the relay user and the second edge user. Both OMA and NOMA use full-duplex. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0021] The present invention provides a full-duplex relay transmission method based on rate division multiple access, comprising: A three-user bidirectional relay system model based on rate division multiple access is set up, which includes a relay user, a first edge user and a second edge user, and is a time division duplex system with channel reciprocity; the information transmission process follows the bidirectional RSMA communication strategy of simultaneous direct transmission and cooperation, and is divided into two time slots; In the first time slot, the relay user communicates with the two edge users using downlink RSMA; at the same time, the two edge users send the information they want to exchange to the relay user using uplink RSMA; In the second time slot, the relay user decodes and forwards the uplink RSMA signal received in the first time slot to implement information exchange between the two edge users; at the same time, the two edge users continue to communicate with the relay user using the uplink RSMA.

[0022] Example 1 Figure 1This is a brief flow chart of a full-duplex relay transmission method based on RSMA provided by the present invention. This flow chart only shows the logical sequence of the method described in this embodiment. In other possible embodiments of the present invention, different Figure 1 The steps shown or described are accomplished in the order shown.

[0023] See also Figure 1 The method of this implementation specifically includes the following steps: A three-user bidirectional relay system model based on rate division multiple access is set up, which includes a relay user, a first edge user and a second edge user, and is a time division duplex system with channel reciprocity; the information transmission process follows the bidirectional RSMA communication strategy of simultaneous direct transmission and cooperation, and is divided into two time slots, namely the first time slot and the second time slot; In the first time slot, the relay user uses downlink RSMA to broadcast a power domain superposition coded signal containing information required by two edge users; At the same time, the two edge users use uplink RSMA to send the information they need to exchange to the relay user; specifically, the first edge user splits its own information into two parts and sends it, while the second edge user directly sends its own information; In the second time slot, the relay user decodes the information to be exchanged received in the first time slot and forwards it to the two edge users; At the same time, the two edge users use uplink RSMA to send the information required by the relay user to the relay user; specifically, the first edge user splits its own information into two parts and sends it, while the second edge user directly sends its own information; Optionally, in a specific embodiment, the following specific steps are included: Step 1: Set up a three-user two-way relay system model based on rate division multiple access, which includes a relay user, a first edge user and a second edge user. The two edge users cannot communicate directly due to long distance or obstacles, and need the help of the relay user to achieve information exchange; in this model, the relay user and the two edge users all work in full-duplex mode.

[0024] The information transmission process is divided into two equal time slots, namely the first time slot and the second time slot. Figure 2 shown.

[0025] Defining relay users Required from the first edge users and second edge users The corresponding information carrying signals are and , the first edge user Required from relay user and second edge users The corresponding information carrying signals are and , the second edge user Required from relay user and first edge users The corresponding information carrying signals are and ,in and for the information to be exchanged; ,in , and Respectively represent users , and The corresponding transmit power.

[0026] Step 2: In the first time slot, relay user Press the RSMA criteria down and Split into , and And perform superposition coding; specifically, the relay user will Split into public stream parts and the private stream corresponding to the first edge user ; At the same time, the relay user will Split into public stream parts and the private stream corresponding to the second edge user ; Subsequently, the relay user will and Synthesize a public stream , and is encoded and forwarded together with the other two private streams. In this embodiment, the ratio parameters of the public stream and the private stream and the power allocation coefficient can be set according to actual needs. While decoding part of the interference, the other part of the interference is treated as noise, that is, by adjusting the ratio parameters of the public stream and the private stream and the power allocation coefficient, the ratio between the interference to be decoded and the interference regarded as noise is adjusted, so as to achieve flexible management of interference.

[0027] Relay User The superposition coded signal in this time slot can be expressed as ,in , and Respectively represent signals , and The corresponding power allocation coefficient satisfies .

[0028] Step 3: In the first time slot, follow the uplink RSMA principle, the first edge user Split for and At the same time, the second edge user Direct transfer For relay users .

[0029] First edge user The superposition coded signal in this time slot can be expressed as ,in represents the power allocation coefficient, satisfying .

[0030] Second edge user The superposition coded signal in this time slot can be expressed as .

[0031] Step 4: At this point, the user , and The received signal in the first time slot can be expressed as: (1); (2); (3); The parameters and Respectively represent the first edge user in the first time slot , Second edge users With relay users The channel coefficient between , and Represent the first time slot relay users , the first edge user and second edge users The self-interference channel, , and Represent the first time slot relay users , the first edge user and second edge users The residual interference coefficient of self-interference elimination, and satisfy , , and Represent the first time slot relay users , the first edge user and second edge users The mean is zero and the variance is Additive Gaussian white noise with complex Gaussian distribution.

[0032] Step 5: According to the downlink RSMA principle, the edge user uses the serial interference cancellation algorithm to decode the public stream and the private stream it needs in sequence. The first time slot decoded signal and The signal-to-interference-noise ratio can be expressed as: (4); (5); in Relay users and first edge users The transmit signal-to-noise ratio.

[0033] Similarly, the second edge user The first time slot decoded signal The signal-to-interference-noise ratio can be expressed as: (6); (7).

[0034] Step 6: According to the uplink RSMA principle, relay users Then we only need to use serial interference cancellation to decode the signals in sequence. , and That is, the corresponding signal to interference and noise ratio can be expressed as: (8); (9); (10); in Indicates the second edge user The transmit signal-to-noise ratio.

[0035] Step 7: In the second time slot, following the uplink RSMA principle, the first edge user Split for and At the same time, the second edge user Direct transfer For relay users .

[0036] First edge user The superposition coded signal in this time slot can be expressed as ,in represents the power allocation coefficient, satisfying .

[0037] Second edge user The superposition coded signal in this time slot can be expressed as .

[0038] Step 8: In the second time slot, relay user The information of the edge user received in the first time slot is decoded and superimposed using physical layer network coding, which can be expressed as . Relay User The superposition coded signal in this time slot can be expressed as .

[0039] Step 9: At this point, the user , and The received signal in the second time slot can be expressed as: (11); (12); (13); The parameters and Respectively represent the first edge user in the second time slot , Second edge users With relay users The channel coefficient between , and Represent the second time slot relay users , the first edge user and second edge users The self-interference channel, , and Represent the second time slot relay users , the first edge user and second edge users The residual interference coefficient of self-interference elimination, and satisfy , , and Represent the second time slot relay users , the first edge user and second edge users The mean is zero and the variance is Additive Gaussian white noise with complex Gaussian distribution.

[0040] Step 10: Since the edge user has prior information about the signal sent in its first time slot, it can eliminate the signal component sent in its first time slot from the received signal, and then directly decode the signal sent in the first time slot of another edge user. The second time slot decoded signal The signal-to-interference-noise ratio can be expressed as: (14); Similarly, the second edge user The second time slot decoded signal The signal-to-interference-noise ratio can be expressed as: (15).

[0041] Step 11: According to the uplink RSMA principle, relay users Then we only need to use serial interference cancellation to decode the signals in sequence. , and That is, the corresponding signal to interference and noise ratio can be expressed as: (16); (17); (18).

[0042] To verify the beneficial effects of the present invention, the following steps will be specifically implemented: Assume that the power allocation coefficients are , , , the residual interference coefficient of self-interference elimination is uniformly set to 0.05. All channel coefficients obey the complex Gaussian distribution, that is, satisfying , , , .in represents the channel power between nodes. In this embodiment, the power of each channel is set to , , , .

[0043] Figure 3 The graphs showing the variation of system traversal and capacity with the transmission signal-to-noise ratio for the different transmission methods described in this embodiment. Figure 3The black solid curve in the middle represents the theoretical value of the traversal and capacity of the transmission method described in this embodiment, and the black symbol points represent the simulation values, and the theoretical value and the simulation value can overlap well. The green symbol line and the blue symbol line represent the traversal and capacity of the traditional NOMA method and the OMA method, respectively. It can be seen from the figure that the scheme proposed in the present invention can achieve better system traversal and capacity performance than the traditional NOMA method and the OMA method under different transmission signal-to-noise ratios. This is because the rate of RSMA is the sum of the rates of each sub-message split, while the rate of each user in NOMA and OMA is only to decode a single message. At the same time, the traversal and capacity of NOMA are better than OMA because NOMA can transmit more signals under the same time resources. For example: when the transmission signal-to-noise ratio is 40dB, the traversal and capacity of the full-duplex relay transmission method based on rate division multiple access proposed in the present invention is 6.98 bps / Hz, while the traversal and capacity of the traditional NOMA method is 6.50 bps / Hz, and the traversal and capacity of the OMA method is 5.95 bps / Hz.

[0044] Example 2 In order to evaluate the traversal and capacity performance of the technical solution of the present invention under different channel powers, this embodiment assumes that the signal-to-noise ratio at the base station is 25dB, and other parameters are consistent with the situation in Example 1. The superiority of the traversal and capacity performance of the technical solution of the present invention is verified by changing the channel power between the two edge users and the relay user. Because the traditional NOMA method requires that one of the two channels at the two ends is better and the other is worse, in order to make a fair comparison, the channel power between the first edge user and the relay user is set to be greater than or equal to the channel power between the second edge user and the relay user. Specifically, this embodiment assumes Figure 4 The channel power between the second edge user and the relay user is 1. Figure 5 The channel power between the first edge user and the relay user is 2.

[0045] Figure 4 A curve diagram showing the system traversal and capacity of different transmission methods described in this embodiment as a function of the channel power between the relay user and the first edge user is shown. Figure 4The solid black curve represents the theoretical value of the traversal and capacity of the transmission method described in this embodiment, and the black symbol points represent the simulation values. The theoretical value and the simulation value can overlap well. The green symbol line and the blue symbol line represent the traversal and capacity of the traditional NOMA method and the OMA method, respectively. As can be seen from the figure, the scheme proposed in the present invention can achieve better traversal and capacity performance than the traditional NOMA method and the OMA method under different channel powers between the relay user and the first edge user, and with the increase of the channel power, the traversal and capacity of the three schemes are improved to varying degrees. This is because the increase in channel power means that the channel quality has improved, which can increase the rate of the relay users and the first edge users in all schemes, thereby increasing the overall traversal and capacity. For example: when the channel power between the first edge user and the relay user is 1.5, the traversal and capacity of the full-duplex relay transmission method based on rate division multiple access proposed in the present invention is 7.25 bps / Hz, while the traversal and capacity of the traditional NOMA method is 6.86 bps / Hz, and the traversal and capacity of the OMA method is 6.20 bps / Hz.

[0046] Figure 5 A curve diagram showing the variation of system traversal and capacity of different transmission methods described in this embodiment with the channel power between the relay user and the second edge user. Figure 5 The solid black curve represents the theoretical value of the traversal and capacity of the transmission method described in this embodiment, and the black symbol points represent the simulation values, and the theoretical value and the simulation value can overlap well. The green symbol line and the blue symbol line represent the traversal and capacity of the traditional NOMA method and the OMA method, respectively. As can be seen from the figure, the scheme proposed in the present invention can achieve better traversal and capacity performance than the traditional NOMA method and the OMA method under different channel powers between the relay user and the second edge user, and with the increase of channel power, the traversal and capacity of the three schemes are improved to varying degrees. This is because the increase in channel power means that the channel quality has improved, which can increase the rate of the relay user and the second edge user in all schemes, thereby increasing the overall traversal and capacity. For example: when the channel power between the second edge user and the relay user is 1.5, the traversal and capacity of the full-duplex relay transmission method based on rate division multiple access proposed in the present invention is 7.83 bps / Hz, while the traversal and capacity of the traditional NOMA method is 7.50 bps / Hz, and the traversal and capacity of the OMA method is 6.86 bps / Hz.

[0047] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0048] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A full-duplex relay transmission method based on rate division multiple access, characterized in that: The method comprises the following steps: A three-user bidirectional relay system model based on rate division multiple access is set up, which includes a relay user, a first edge user and a second edge user, and is a time division duplex system with channel reciprocity; the information transmission process follows the bidirectional RSMA communication strategy of simultaneous direct transmission and cooperation, and is divided into two time slots, namely the first time slot and the second time slot; In the first time slot, the relay user communicates with the two edge users using downlink RSMA; at the same time, the two edge users send the information they want to exchange to the relay user using uplink RSMA; In the second time slot, the relay user decodes and forwards the uplink RSMA signal received in the first time slot to implement information exchange between the two edge users; at the same time, the two edge users continue to communicate with the relay user using the uplink RSMA; Among them, when the first edge user uses the uplink RSMA to send information, it splits its own information into two parts, superimposes the encoding and forwards it, while the second edge user directly sends its own information.

2. The full-duplex relay transmission method based on rate division multiple access according to claim 1, characterized in that: The first time slot and the second time slot have the same duration.

3. The full-duplex relay transmission method based on rate division multiple access according to claim 1, characterized in that: In the first time slot and the second time slot, the relay user uses a serial interference cancellation algorithm to sequentially decode the first part of the information split from the first edge user, the information of the second edge user, and the second part of the information split from the first edge user.

4. The full-duplex relay transmission method based on rate division multiple access according to claim 1, characterized in that: In the first time slot, the relay user uses downlink RSMA to broadcast a power domain superposition coded signal containing information required by two edge users; in the second time slot, the relay user decodes the information to be exchanged received in the first time slot and forwards it to the two edge users.

5. The full-duplex relay transmission method based on rate division multiple access according to claim 4, characterized in that: In the second time slot, the relay user decodes the information of the edge user received in the first time slot and superimposes it using physical layer network coding, and then broadcasts it; the edge user eliminates the signal component sent by its own first time slot from the received signal based on the prior information of the signal sent by its own first time slot, and directly decodes the signal sent by another edge user in the first time slot.

6. The full-duplex relay transmission method based on rate division multiple access according to claim 1, characterized in that: According to the downlink RSMA principle, the relay user divides the information required by the first edge user into the public stream required by the first edge user and the private stream required by the first edge user; at the same time, the relay user divides the information required by the second edge user into the public stream required by the second edge user and the private stream required by the second edge user; then, the relay user synthesizes the public stream required by the first edge user and the public stream required by the second edge user into a public stream, and superimposes the encoding and forwarding it together with the other two private streams.

7. The full-duplex relay transmission method based on rate division multiple access according to claim 6, characterized in that: In the first time slot, according to the downlink RSMA principle, the two edge users use a serial interference cancellation algorithm to sequentially decode the public stream and the private streams they need.

8. The full-duplex relay transmission method based on rate division multiple access according to claim 1, characterized in that: In the first time slot and the second time slot, following the uplink RSMA principle, the first edge user is divided into two virtual users, and then the information of the first edge user is split into two parts and mapped to the two virtual users respectively, and then the two virtual users send their own information.

9. The full-duplex relay transmission method based on rate division multiple access according to claim 1, characterized in that: The relay user and the two edge users all work in full-duplex mode.

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