A terminal aggregation cooperative transmission method based on non-orthogonal multiple access

Abstract

The present invention relates to a terminal aggregation cooperative transmission method based on non-orthogonal multiple access, comprising: a network access point detects and obtains the channel state between each terminal user and each cooperative node; based on the channel state, the cooperative node and the terminal user are matched into a joint transmission cluster; the transmission power is allocated to each terminal user in the joint transmission cluster, and the total transmission power of the joint transmission cluster is calculated; spectrum resources are allocated to each joint transmission cluster based on the total transmission power, the terminal user in the joint transmission cluster sends information on the allocated spectrum resources according to the allocated transmission power, the cooperative node in the joint transmission cluster receives the terminal information, and performs continuous interference elimination and decoding operations on the terminal information based on the channel state; after the cooperative node completes decoding of the terminal information, the terminal information is forwarded to the network access point in the reverse order of decoding during continuous interference elimination to complete the transmission. The present invention can achieve the improvement of network transmission reliability, coverage expansion, and rate enhancement.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a terminal aggregation cooperative transmission method based on non-orthogonal multiple access. Background Art

[0002] With the rapid development of Internet of Things technology, especially in daily consumption and production application scenarios such as smart home, Internet of Things, and Internet of Vehicles, the number of devices accessing the network has also exploded, which has led to the demand for large-scale device access to the network. Such large-scale access poses a great challenge to limited spectrum resources, and the existing network structure is difficult to meet the network performance of such large-scale access devices. The existing solution is to add a certain scale of small and micro base stations to the network structure. Users access small and micro base stations and communicate with macro base stations or other terminals through their forwarding, forming an ultra-dense network (UDN). Users can improve spectrum efficiency and alleviate the problem of limited spectrum resources by using the same spectrum resources in a restricted geographical area. However, this approach still cannot avoid interference from the same channel. As the density of access devices increases further, the impact of interference will increase sharply, and the scarcity of spectrum resources still limits the network performance of IoT devices. In addition, there are some designs that use the non-orthogonal multiple access (NOMA) method to improve spectrum efficiency. By performing continuous interference elimination and decoding of signals of users with different receiving powers at the base station, multiple users can reuse the same spectrum resources to improve spectrum efficiency. However, this approach will still cause the user who is decoded first to be subject to higher interference, thereby limiting its transmission rate.

[0003] Secondly, with the changes and development of business forms and the further expansion and extension of application scenarios, the access equipment capabilities are heterogeneous, including signal processing capabilities, power consumption, volume, etc., and the communication indicators are more stringent and diverse, including coverage, rate, reliability, latency and power consumption. Among the existing wireless communication design methods, there are methods such as relaying, repeated transmission, and multi-path transmission to achieve coverage expansion and reliability improvement.

[0004] In view of the above two problems, in the face of future complex systems, diverse performance indicators and multi-type terminals, the present invention proposes a terminal aggregation cooperative transmission method based on non-orthogonal multiple access. Summary of the invention

[0005] The purpose of the present invention is to provide a terminal aggregation cooperative transmission method based on non-orthogonal multiple access, which improves spectrum efficiency through non-orthogonal multiple access, and combines the aggregation cooperative transmission between terminals to achieve reliability improvement, coverage expansion or rate enhancement.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A terminal aggregation cooperative transmission method based on non-orthogonal multiple access, comprising:

[0008] The network access point detects and obtains the channel status between each terminal user and each cooperative node;

[0009] matching the cooperative nodes and the end users into a joint transmission cluster based on the channel state;

[0010] Allocating transmission power to each terminal user in the joint transmission cluster, and calculating the total transmission power of the joint transmission cluster;

[0011] Allocating spectrum resources to each joint transmission cluster based on the total transmission power, the terminal users in the joint transmission cluster transmit information on the allocated spectrum resources according to the allocated transmission power, the cooperative nodes in the joint transmission cluster receive the terminal information, and perform continuous interference cancellation and decoding operations on the terminal information based on the channel state;

[0012] After the cooperation node completes decoding of the terminal information, the cooperation node forwards the terminal information to the network access point in the reverse order of decoding during continuous interference cancellation to complete the transmission.

[0013] Optionally, the network access point detecting and acquiring the channel status between each terminal user and each cooperation node includes:

[0014] The network access point records the channel status between the terminal device and the cooperative node and the network access point according to the channel status information fed back by the terminal user and the cooperative node; the cooperative node records the channel status between the terminal device and the cooperative node by identifying the channel status information fed back by the terminal user and feeds it back to the network access point.

[0015] Optionally, matching the cooperative node and the terminal user into a joint transmission cluster based on the channel state includes:

[0016] Initialize the joint transmission cluster Where C represents the set of cooperative nodes in the joint transmission cluster, and U represents the set of terminal users in the joint transmission cluster;

[0017] Acquire a channel condition between a beneficial cooperation node of a terminal user u and the terminal user u, and arrange the channel conditions in descending order of magnitude to form a channel condition set;

[0018] Selecting a main cooperation node based on the channel condition set, updating the main cooperation node to the cooperation node set C, and updating the terminal user u to the terminal user set U;

[0019] Selecting a secondary cooperation node based on the channel condition set, and looping through the terminal users u' except the terminal user u based on the secondary cooperation node and the cooperation node set C to obtain a channel condition matrix M;

[0020] If the channel condition matrix M still does not meet the preset condition until all the terminal users u' are traversed, the secondary cooperation node is deleted and a new secondary cooperation node is selected to continue the loop traversal;

[0021] If the channel condition matrix M meets the preset condition, the secondary cooperation node is updated to the cooperation node set C, and all the terminal users u' traversed in the loop are updated to the terminal user set U;

[0022] The above operations are repeated until the number of cooperative nodes in the joint transmission cluster reaches a specified upper limit or the traversal of all terminal users is completed, and the matched joint transmission cluster set is output.

[0023] Optionally, the preset condition is:

[0024]

[0025] Among them, col(·) represents the column index value, min(·) represents the minimum value, and M i represents the i-th row of the channel condition matrix M, M j represents the j-th column of the channel condition matrix M.

[0026] Optionally, allocating transmission power to each terminal user in the joint transmission cluster and calculating the total transmission power of the joint transmission cluster includes:

[0027] Setting a power allocation factor vector for the joint transmission cluster;

[0028] The power allocation factor vector is used as the whale position information, the total transmission power of the joint transmission cluster is used as the population fitness, the whale optimization algorithm is executed, and the optimal power allocation factor and the optimal total transmission power of the joint transmission cluster are output;

[0029] After traversing all joint transmission clusters, the optimal power allocation factors and optimal total transmission powers of all joint transmission clusters are output.

[0030] Optionally, allocating spectrum resources to each joint transmission cluster based on the total transmit power includes:

[0031] Construct a conflict graph G = (V, ε, W), where V is the end user in all joint transmission clusters, ε is the conflict relationship between each vertex, and W is the weight of each vertex, which is represented by the optimal total transmission power of each joint transmission cluster;

[0032] Finding a vertex with the largest weight in the conflict graph, and allocating a channel resource to the joint transmission cluster represented by the vertex with the largest weight;

[0033] Find the neighboring vertices of the vertex with the largest weight, delete the vertex with the largest weight and its neighboring vertices, and update the conflict graph;

[0034] Continue to iterate and search for the vertex with the largest weight for the updated conflict graph until the channel resources are fully allocated or all terminal users are allocated channel resources, output the mapping between all joint transmission clusters and the channel resources, and complete the spectrum resource allocation of each joint transmission cluster.

[0035] Optionally, the method for finding the vertex with the largest weight in the conflict graph is:

[0036]

[0037] Among them, v i is the vertex with the largest weight in the conflict graph.

[0038] Optionally, the method for updating the conflict graph is:

[0039]

[0040] in, The conflict graph G i The vertex v with the largest weight i The neighbor vertices of G i+1 This is the updated conflict graph.

[0041] The beneficial effects of the present invention are:

[0042] The present invention proposes a terminal aggregation cooperative transmission method based on non-orthogonal multiple access, and the message of a terminal device can be received and forwarded by multiple cooperative nodes in the same joint transmission cluster, and the users in the same joint transmission cluster can communicate with the writing node on the same spectrum resource with the help of non-orthogonal multiple access technology; the matched joint transmission cluster can ensure that the order of continuous interference elimination of each cooperative node is different, and can ensure that the message of each terminal user can be finally decoded by at least one cooperative node to achieve interference-free transmission. Therefore, the terminal devices in the same joint transmission cluster can perform interference-free transmission on the same spectrum resource, which can ensure data transmission of more terminal devices under the premise of using only the same spectrum resource.

[0043] The present invention improves spectrum efficiency through non-orthogonal multiple access, and combines aggregated cooperative transmission between terminals to achieve reliability improvement, coverage expansion or rate enhancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A flow chart of a terminal aggregation cooperative transmission method based on non-orthogonal multiple access according to an embodiment of the present invention;

[0046] Figure 2 A flow chart of a joint transmission cluster matching algorithm according to an embodiment of the present invention;

[0047] Figure 3 A power allocation algorithm flow chart of an embodiment of the present invention;

[0048] Figure 4 A flow chart of a channel resource allocation algorithm according to an embodiment of the present invention;

[0049] Figure 5 This is a flow chart of terminal aggregation cooperative transmission based on non-orthogonal multiple access according to an embodiment of the present invention;

[0050] Figure 6 Schematic diagram of the joint transmission cluster receiving power and decoding order according to an embodiment of the present invention

[0051] Figure 7 A schematic diagram of a joint transmission cluster pairing algorithm according to an embodiment of the present invention;

[0052] Figure 8 A schematic diagram of a power allocation algorithm according to an embodiment of the present invention;

[0053] Fig. 9 A schematic diagram of a channel resource allocation algorithm according to an embodiment of the present invention;

[0054] Fig.10 The cumulative distribution function of the signal-to-noise ratio of the terminal device when spectrum resources are lacking according to different strategies of the embodiment of the present invention;

[0055] Fig.11 The terminal user capacity varies with the number of sub-channels under different strategies of the embodiments of the present invention;

[0056] Fig.12 The terminal user capacity varies with the number of terminal devices under different strategies of the embodiments of the present invention;

[0057] Fig.13 The spectrum efficiency varies with the transmission power of the terminal device under different strategies of the embodiments of the present invention. DETAILED DESCRIPTION

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

[0059] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] This embodiment provides a terminal aggregation cooperative transmission method based on non-orthogonal multiple access, such as Figure 1 As shown, including:

[0061] The network access point detects and obtains the channel status between each terminal user and each cooperative node;

[0062] Matching cooperative nodes and end users into joint transmission clusters based on channel status;

[0063] Allocate transmission power to each terminal user in the joint transmission cluster and calculate the total transmission power of the joint transmission cluster;

[0064] Allocate spectrum resources to each joint transmission cluster based on the total transmission power. The terminal users in the joint transmission cluster transmit information on the allocated spectrum resources according to the allocated transmission power. The cooperative nodes in the joint transmission cluster receive the terminal information and perform continuous interference cancellation and decoding operations on the terminal information based on the channel state.

[0065] After the cooperative node completes decoding of the terminal information, it forwards the terminal information to the network access point in the reverse order of decoding during continuous interference elimination to complete the transmission.

[0066] Furthermore, the network access point detects and obtains the channel status between each terminal user and each cooperation node, including:

[0067] The network access point records the channel status between the terminal device and the cooperative node and the network access point according to the channel status information fed back by the terminal user and the cooperative node; the cooperative node records the channel status between the terminal device and the cooperative node by identifying the channel status information fed back by the terminal user and feeds it back to the network access point.

[0068] Further, matching the cooperative nodes and the terminal users into a joint transmission cluster based on the channel state includes:

[0069] Initialize the joint transmission cluster Where C represents the set of cooperative nodes in the joint transmission cluster, and U represents the set of terminal users in the joint transmission cluster;

[0070] Obtain the channel conditions between the beneficial cooperation node of the terminal user u and the terminal user u, and arrange the channel conditions in descending order to form a channel condition set;

[0071] Select a main cooperation node based on the channel condition set, update the main cooperation node to the cooperation node set C, and update the terminal user u to the terminal user set U;

[0072] Select a secondary cooperation node based on the channel condition set, and loop through the terminal user u' except the terminal user u based on the secondary cooperation node and the cooperation node set C to obtain the channel condition matrix M;

[0073] If the channel condition matrix M still does not meet the preset conditions until all terminal users u' are traversed, the secondary cooperation node is deleted and a new secondary cooperation node is selected to continue the loop traversal;

[0074] If the channel condition matrix M meets the preset conditions, the secondary cooperation node is updated to the cooperation node set C, and all the terminal users u' traversed in the loop are updated to the terminal user set U;

[0075] Repeat the above operations until the number of cooperative nodes in the joint transmission cluster reaches the specified upper limit or the traversal of all terminal users is completed, and output the matched joint transmission cluster set.

[0076] Furthermore, allocating transmission power to each terminal user in the joint transmission cluster and calculating the total transmission power of the joint transmission cluster includes:

[0077] Setting a power allocation factor vector for the joint transmission cluster;

[0078] The power allocation factor vector is used as the whale position information, and the total transmission power of the joint transmission cluster is used as the population fitness. The whale optimization algorithm is executed to output the optimal power allocation factor and the optimal total transmission power of the joint transmission cluster.

[0079] After traversing all joint transmission clusters, the optimal power allocation factors and optimal total transmission powers of all joint transmission clusters are output.

[0080] Furthermore, allocating spectrum resources to each joint transmission cluster based on the total transmit power includes:

[0081] Construct a conflict graph G = (V, ε, W), where V is the end user in all joint transmission clusters, ε is the conflict relationship between each vertex, and W is the weight of each vertex, which is represented by the optimal total transmission power of each joint transmission cluster;

[0082] Find the vertex with the largest weight in the conflict graph and allocate a channel resource to the joint transmission cluster represented by the vertex with the largest weight;

[0083] Find the neighbor vertices of the vertex with the largest weight, delete the vertex with the largest weight and its neighbor vertices, and update the conflict graph;

[0084] Continue to iterate and search for the vertex with the largest weight for the updated conflict graph until the channel resources are fully allocated or all end users are allocated channel resources, output the mapping between all joint transmission clusters and channel resources, and complete the spectrum resource allocation of each joint transmission cluster.

[0085] The device that provides wireless data services to mobile terminals is called a network access point, which can be a base station in a cell, or a wifi access device. The area covered by a network access point is called a coverage area. A coverage area includes multiple mobile terminals or users, and the multiple mobile terminals and the network access point are relatively static or moving. Furthermore, the multiple mobile terminals covered by a network access point can change over time, and the number can be variable. The wireless communication technology in this embodiment is based on the 5G standard, or an evolved version of the 5G standard, or a wireless protocol such as wifi technology. The mobile terminal and network access point in this embodiment are implemented based on the above-mentioned wireless communication technology. Specifically including the following contents:

[0086] Step 1: The network access point detects and obtains the channel status between each terminal user and each cooperative node.

[0087] Specifically: the network access point records the channel status between the terminal device and the cooperative node and the network access point according to the channel status information fed back by the terminal user and the cooperative node; the cooperative node records the channel status between the terminal device and the cooperative node by identifying the channel status information fed back by the terminal user and feeds it back to the network access point.

[0088] Step 2: Match the cooperative nodes and end users into joint transmission clusters based on the channel status.

[0089] Initialize the joint transmission cluster Where C represents the set of cooperative nodes in the joint transmission cluster, and U represents the set of terminal users in the joint transmission cluster;

[0090] Obtain the channel conditions between the beneficial cooperation node of the terminal user u and the terminal user u, and arrange the channel conditions in descending order to form a channel condition set;

[0091] Select a main cooperation node based on the channel condition set, update the main cooperation node to the cooperation node set C, and update the terminal user u to the terminal user set U;

[0092] Select a secondary cooperation node based on the channel condition set, and loop through the terminal user u' except the terminal user u based on the secondary cooperation node and the cooperation node set C to obtain the channel condition matrix M;

[0093] If the channel condition matrix M still does not meet the preset conditions until all terminal users u' are traversed, the secondary cooperation node is deleted and a new secondary cooperation node is selected to continue the loop traversal;

[0094] If the channel condition matrix M meets the preset conditions, the secondary cooperation node is updated to the cooperation node set C, and all the terminal users u' traversed in the loop are updated to the terminal user set U;

[0095] Repeat the above operations until the number of cooperative nodes in the joint transmission cluster reaches the specified upper limit or the traversal of all terminal users is completed, and output the matched joint transmission cluster set.

[0096] Specifically, a joint transmission cluster consists of several cooperative nodes and end users. A feasible joint transmission cluster satisfies that for any cooperative node, the channel states between the end users in the joint transmission cluster and the end users are arranged in descending order, and the user with the largest order is different from the other cooperative nodes. Figure 2 As shown in the figure, the specific process of the joint transmission cluster pairing algorithm is as follows:

[0097] For a user u, obtain the channel condition set H between all cooperative nodes that are beneficial to the user u and the user u. s,u . Set H s,u ={h s(1),u ,h s(2),u ,...,h S,u}, where h s,u Represents the channel condition between the cooperative node s and the user u. Initialize the joint transmission cluster Where C represents the set of cooperative nodes in a joint transmission cluster, and U represents the set of users in a joint transmission cluster.

[0098] Update user u to the set U, that is, U'=U∪{u}. For the channel condition set H of user u s,u , after arranging them in descending order of channel condition size, we get

[0099] For the arranged channel condition set Select the cooperative node s1 with the best channel condition as its main cooperative node, and update s1 to the cooperative node set C, that is, C'=C∪{s1}. The main cooperative node s1 satisfies the following formula:

[0100]

[0101] For the arranged channel condition set Select the cooperative node s2 with the second best channel condition. The cooperative node s2 satisfies the following formula:

[0102]

[0103] For the obtained second best cooperative node s2 and the existing cooperative node set C, loop through other users u' except user u to obtain a channel condition matrix M of [number of cooperative nodes (|C|+1) x number of users (|U|+1)], where the channel condition matrix is ​​composed of the channel conditions between the above users and cooperative nodes, and assumes that the cooperative node receiving vector is Y, the user sending vector is X, and the noise vector is N:

[0104] Y=MX+N (3)

[0105] The channel condition matrix M needs to satisfy the condition that each row of the matrix has a column minimum value, and the column index values ​​where the minimum values ​​of each row are located are different, that is, the condition is satisfied:

[0106]

[0107] Where col(·) represents the column index value, and min(·) represents the minimum value. If the channel condition matrix M satisfies condition (4), the cooperative nodes and users associated with the matrix are paired into a feasible joint transmission cluster. And the cooperative node set C'=C∪{s2}, the user set U'=U∪{u'}, and the joint transmission cluster set ψ'=ψ∪C'∪U' are updated. The channel condition value corresponding to s2 is changed from Delete

[0108] If the channel condition matrix does not satisfy condition (4), the current user is ignored and the next user is traversed.

[0109] Repeat the above operation until the number of cooperative nodes in a joint transmission cluster reaches the upper limit or there is no combination that meets the requirements. Finally, the set of all feasible joint transmission clusters ξ={ψ1,ψ2,...,ψ N}, the number of feasible joint transmission clusters is N.

[0110] Step 3: Allocate transmission power to each terminal user in the joint transmission cluster, and calculate the total transmission power of the joint transmission cluster.

[0111] Setting a power allocation factor vector for the joint transmission cluster;

[0112] The power allocation factor vector is used as the whale position information, and the total transmission power of the joint transmission cluster is used as the population fitness. The whale optimization algorithm is executed to output the optimal power allocation factor and the optimal total transmission power of the joint transmission cluster.

[0113] After traversing all joint transmission clusters, the optimal power allocation factors and optimal total transmission powers of all joint transmission clusters are output.

[0114] Specifically, Figure 3 As shown, for a joint transmission cluster, a power allocation factor vector A = {a1, a2, ..., a |U|}, where a x represents the power allocation factor and satisfies 0≤a x ≤1. The power allocation factor vector is characterized in that the power allocation factor corresponds to the gain coefficient of the user transmission power in the joint transmission cluster, that is, for user u1 with a maximum transmission power of P, the power of P1=a1P is used for transmission under the action of the power allocation factor.

[0115] The whale optimization algorithm is used to optimize the transmission power allocation factor of the terminal users in each joint transmission cluster. Specifically, the power allocation vector of the joint transmission cluster is used as the whale position information of the whale optimization algorithm and the sum rate of the joint transmission cluster is used as the population fitness for iterative update.

[0116] The whale optimization algorithm outputs the optimal power allocation factor value of the joint transmission cluster after a certain number of iterations, and finally calculates the total rate of each joint transmission cluster by obtaining the optimal power allocation factor of each feasible joint transmission cluster and the known channel state of the network access point.

[0117] Step 4: Allocate spectrum resources to each joint transmission cluster based on the total transmit power.

[0118] Construct a conflict graph G = (V, ε, W), where V is the end user in all joint transmission clusters, ε is the conflict relationship between each vertex, and W is the weight of each vertex, which is represented by the optimal total transmission power of each joint transmission cluster;

[0119] Find the vertex with the largest weight in the conflict graph and allocate a channel resource to the joint transmission cluster represented by the vertex with the largest weight;

[0120] Find the neighbor vertices of the vertex with the largest weight, delete the vertex with the largest weight and its neighbor vertices, and update the conflict graph;

[0121] Continue to iterate and search for the vertex with the largest weight for the updated conflict graph until the channel resources are fully allocated or all end users are allocated channel resources, output the mapping between all joint transmission clusters and channel resources, and complete the spectrum resource allocation of each joint transmission cluster.

[0122] Specifically, Figure 4As shown in Figure 1, the network access point constructs a conflict graph based on the feasible joint transmission clusters obtained in step 3 and their optimal sum rate. The weights of the vertices in the conflict graph are composed of the optimal sum rate of the joint transmission cluster. The conflict graph is G = (V, ε, W), where the point set V represents the NOMA user groups in all feasible joint transmission clusters; the edge set ε represents the conflict relationship between each point, that is, if two points contain the same terminal user, there is a conflict edge between the two points; the weight set W represents the weight of each point in the graph, which is composed of the sum rate of each joint transmission cluster.

[0123] The specific characteristics of the network access point using a greedy algorithm to solve the maximum independent set of the above conflict graph are as follows: first, find the point with the largest weight from the graph G, that is:

[0124]

[0125] Update the vertex to V * =V * ∪{v i}, allocate channel resources to the NOMA group users associated with this vertex. Then, find the users with v according to the conflict graph. i The set of neighbor vertices of a vertex Finally, after finding the maximum weight vertex and its neighboring vertices, delete these vertices from the original graph and update the original graph, that is:

[0126]

[0127] According to the above steps, the conflict graph is iteratively updated until the channel resources are fully allocated or all NOMA groups are allocated channel resources. Finally, all mappings between channel resources and users are output.

[0128] Step 5: The terminal users in the joint transmission cluster send information on the allocated spectrum resources according to the allocated transmission power. The cooperative nodes in the joint transmission cluster receive the terminal information and perform continuous interference elimination and decoding operations on the terminal information based on the channel status. After the cooperative nodes complete decoding of the terminal information, they forward the terminal information to the network access point in the reverse order of decoding during continuous interference elimination to complete the transmission.

[0129] Specifically, the terminal users in the same matched joint transmission cluster use the transmission power to send information to the cooperative nodes in the joint transmission cluster on the same spectrum resources.

[0130] The cooperative nodes in the joint transmission cluster simultaneously receive information from the terminals of the same joint transmission cluster. And at the cooperative nodes, the received superimposed signals are respectively subjected to continuous interference elimination according to the descending order of the channel state from the terminal to the cooperative node, and the information from different terminals is decoded.

[0131] After the cooperative node successfully decodes the terminal information, it preferentially forwards the terminal user information that was last decoded during the continuous interference cancellation to the network access point.

[0132] Combine the following Figure 5-Figure 9 The implementation of a terminal aggregation cooperative transmission method based on non-orthogonal multiple access proposed in this embodiment is described in a specific scenario, including the following contents:

[0133] like Figure 5 As shown, the wireless network 100 includes a network access point 101, cooperative nodes 102 and 103, terminal users 104 and 105, and a joint transmission cluster 106 composed of the cooperative nodes and the terminal users.

[0134] The network access point 101 matches the cooperative nodes 102 , 103 and the terminal users 104 and 105 into a joint transmission cluster 106 according to step 2 above.

[0135] The terminal users 104 and 105 send messages to the cooperative nodes 102 and 103 respectively through the multicast channel on the same spectrum resource.

[0136] The cooperating nodes 102 and 103 receive messages from two end users 104 and 105 and perform successive interference cancellation to decode the messages from the different end devices.

[0137] After decoding the message from the end user, the cooperation nodes 102 and 103 forward the messages 105 and 104 to the network access point 101 respectively.

[0138] The network access point 101 provides data services to terminals within the coverage area and performs resource allocation.

[0139] like Figure 6 As shown, a joint transmission cluster 200 includes three cooperative nodes 201 , 202 and 203 , and three terminal users 204 , 205 and 206 .

[0140] The decoding order of the cooperative node 201 in the joint transmission cluster is 206, 205, 204; the decoding order of the cooperative node 202 in the joint transmission cluster is 206, 204, 205; the decoding order of the cooperative node 203 in the joint transmission cluster is 204, 205, 206.

[0141] like Figure 7 As shown, in wireless network 300, there are terminal users 304, 305 and 306 to be matched, and there are cooperative nodes 302 and 303 to be matched. The channel condition matrix between terminal users 304, 305 and cooperative nodes 302, 303 is 307; the channel condition matrix between terminal users 304, 306 and cooperative nodes 302, 303 is 308.

[0142] Using the joint transmission cluster matching algorithm in step 2 above, the terminal user 304 selects its first best cooperation node 302 and its second best cooperation node 303 as the initial joint transmission cluster according to the sorted channel condition vectors.

[0143] First, traverse the terminal user 305. Assume that 305 joins the joint transmission cluster. It forms a channel condition matrix 307 with 304, 302 and 303. The minimum value 324 of the first row of the matrix 307 appears in the first column, and the minimum value 334 of the second row of the matrix 307 also appears in the first column, which does not meet the conditions in formula (4). 305 cannot join the joint transmission cluster.

[0144] When 305 cannot join the current joint transmission cluster, 305 is discarded and the traversal of the terminal user 306 continues, assuming that 306 joins the current joint transmission cluster. The terminal user 306 and the elements 302, 303 and 304 in the current joint transmission cluster form a channel condition matrix 308. The minimum value 326 of the first row of the matrix 308 appears in the second column, and the minimum value 334 of the second row of the matrix 308 appears in the first column, which meets the conditions in formula (4). 306 can join the joint transmission cluster.

[0145] The end users 304, 306 and the coordinating nodes 302 and 303 are matched into a feasible joint transmission cluster.

[0146] like Figure 8 As shown, wireless network 400 includes cooperating nodes 401 , 402 , and 403 , and end users 404 , 405 , and 406 .

[0147] The base station allocates power to the terminal users of the matched joint transmission cluster. The specific feature is that the base station allocates respective power allocation factors to the terminal users. After the terminal users are allocated power allocation factors, they send messages to the cooperation nodes with corresponding power.

[0148] Table 1 shows the access rate of terminal users when the base station uses a fixed power allocation strategy and a power allocation strategy based on the whale optimization algorithm.

[0149] Table 1

[0150]

[0151] When fixed power allocation is used, the power allocation factors 414, 415 and 416 of the terminal users 404, 405 and 406 are all 1, that is, the maximum power is used for transmission. At this time, the access rates of the terminal users 404, 405 and 406 at the cooperative node are 8.09, 7.79 and 1.25 respectively.

[0152] When the power allocation strategy based on the whale optimization algorithm is used, the power allocation factors 414, 415 and 416 of the terminal users 404, 405 and 406 are 1, 0.7 and 0.93 respectively. At this time, the access rates of the terminal users 404, 405 and 406 at the cooperative node are 8.09, 7.3 and 8.57 respectively.

[0153] When fixed power allocation is used, the total rate of the joint transmission cluster is 17.13; when the power allocation strategy based on the whale optimization algorithm is used, the total rate of the joint transmission cluster is 23.96. The access rate of the joint transmission cluster can be optimized by using the power allocation strategy based on the whale optimization algorithm.

[0154] like Fig. 9 As shown, in a wireless network 500, a conflict graph 530 is composed of four vertices 510, 511, 512, and 513, wherein vertex 510 includes terminal users 506, 507, and 508, and has a weight of 20.45; vertex 511 includes terminal users 501, 502, and 503, and has a weight of 17.13; vertex 512 includes terminal users 507, 508, and 509, and has a weight of 15.26; vertex 513 includes terminal users 503, 504, and 505, and has a weight of 23.96. There is a common element 503 between vertices 511 and 513, so there is an edge between 511 and 513; there are common elements 507 and 508 between vertices 510 and 512, so there is an edge between 510 and 512. And there are channels 520 and 521 to be allocated in the network.

[0155] The algorithm starts from the conflict graph 530 , finds the vertex 513 with the highest weight in the graph, and allocates channel 520 to it. At this time, vertex 513 and its neighbor vertex 511 are deleted from the conflict graph 530 to obtain an updated conflict graph 531 .

[0156] For the updated conflict graph 531, 510 with the highest weight between vertices 510 and 512 is selected, and channel 521 is allocated to the user in vertex 510. At this time, the channel resources are allocated, and the channel allocation algorithm ends.

[0157] Finally, the allocation of channel resources is completed, and terminal users 503, 504 and 505 are allocated channel 520, and terminal users 506, 507 and 508 are allocated channel 521.

[0158] Comparison and verification:

[0159] This method is compared and verified with other strategies, namely, no interference, partial spectrum sharing, and non-orthogonal multiple access. The cumulative distribution function of the signal-to-noise ratio of the terminal equipment when spectrum resources are scarce is as follows: Fig.10As shown, in this method, a message of a terminal device can be received and forwarded by multiple cooperative nodes in the same joint transmission cluster, and users in the same joint transmission cluster can communicate with the cooperative nodes on the same spectrum resource with the help of non-orthogonal multiple access technology. The matched joint transmission cluster can ensure that the order of continuous interference elimination of each cooperative node is different, and can ensure that the message of each terminal user can be finally decoded by at least one cooperative node to achieve interference-free transmission. Therefore, terminal devices in the same joint transmission cluster can theoretically perform interference-free transmission on the same spectrum resource, which can ensure that more terminal devices send data under the premise of using only the same spectrum resource. This method can obtain the best signal-to-noise ratio performance when spectrum resources are scarce.

[0160] The end-user capacity varies with the number of sub-channels. Fig.11 As shown, this method can increase the access capacity of terminal devices when spectrum resources are relatively limited, and compared with the method without a joint transmission cluster, it increases the overall data transmission capacity of the system.

[0161] The change of terminal user capacity with the number of terminal devices is as follows: Fig.12 As shown, this method can increase the access capacity of terminal devices when the number of terminals is high, and compared with the method without a joint transmission cluster, it increases the overall data transmission capacity of the system.

[0162] The spectrum efficiency changes with the transmission power of the terminal equipment as shown in Fig.13 As shown, this method can achieve higher spectrum efficiency by eliminating interference, increase the data capacity transmitted by the terminal device when the number of spectrum resources is certain, and increase the overall spectrum efficiency of the system compared to the method without joint transmission clusters.

[0163] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A terminal aggregation cooperative transmission method based on non-orthogonal multiple access, characterized in that: include: The network access point detects and obtains the channel status between each terminal user and each cooperative node; matching the cooperative nodes and the end users into a joint transmission cluster based on the channel state; Allocating transmission power to each terminal user in the joint transmission cluster, and calculating the total transmission power of the joint transmission cluster; Allocating spectrum resources to each joint transmission cluster based on the total transmission power, the terminal users in the joint transmission cluster transmit information on the allocated spectrum resources according to the allocated transmission power, the cooperative nodes in the joint transmission cluster receive the terminal information, and perform continuous interference cancellation and decoding operations on the terminal information based on the channel state; After the cooperation node completes decoding of the terminal information, the cooperation node forwards the terminal information to the network access point in the reverse order of decoding during continuous interference elimination to complete the transmission; Wherein, matching the cooperative node and the terminal user into a joint transmission cluster based on the channel state includes: Initialize the joint transmission cluster Where C represents the set of cooperative nodes in the joint transmission cluster, and U represents the set of terminal users in the joint transmission cluster; Acquire a channel condition between a beneficial cooperation node of a terminal user u and the terminal user u, and arrange the channel conditions in descending order of magnitude to form a channel condition set; Selecting a main cooperation node based on the channel condition set, updating the main cooperation node to the cooperation node set C, and updating the terminal user u to the terminal user set U; Selecting a secondary cooperation node based on the channel condition set, and looping through the terminal users u' except the terminal user u based on the secondary cooperation node and the cooperation node set C to obtain a channel condition matrix M; If the channel condition matrix M still does not meet the preset condition until all the terminal users u' are traversed, the secondary cooperation node is deleted and a new secondary cooperation node is selected to continue the loop traversal; If the channel condition matrix M meets the preset condition, the secondary cooperation node is updated to the cooperation node set C, and all the terminal users u' traversed in the loop are updated to the terminal user set U; The above operations are repeated until the number of cooperative nodes in the joint transmission cluster reaches a specified upper limit or the traversal of all terminal users is completed, and the matched joint transmission cluster set is output.

2. The method for terminal aggregation and cooperative transmission based on non-orthogonal multiple access according to claim 1, characterized in that: The network access point detecting and acquiring the channel status between each terminal user and each cooperative node includes: The network access point records the channel status between the terminal device and the cooperative node and the network access point according to the channel status information fed back by the terminal user and the cooperative node; the cooperative node records the channel status between the terminal device and the cooperative node by identifying the channel status information fed back by the terminal user and feeds it back to the network access point.

3. The method for terminal aggregation and cooperative transmission based on non-orthogonal multiple access according to claim 1, characterized in that: The preset conditions are: col(min{M i })≠col(min{M j }), Among them, col(·) represents the column index value, min(·) represents the minimum value, and M i represents the i-th row of the channel condition matrix M, M j represents the j-th column of the channel condition matrix M.

4. The method for terminal aggregation and cooperative transmission based on non-orthogonal multiple access according to claim 1, characterized in that: Allocating transmission power to each terminal user in the joint transmission cluster and calculating the total transmission power of the joint transmission cluster includes: Setting a power allocation factor vector for the joint transmission cluster; The power allocation factor vector is used as the whale position information, the total transmission power of the joint transmission cluster is used as the population fitness, the whale optimization algorithm is executed, and the optimal power allocation factor and the optimal total transmission power of the joint transmission cluster are output; After traversing all joint transmission clusters, the optimal power allocation factors and optimal total transmission powers of all joint transmission clusters are output.

5. The method for terminal aggregation and cooperative transmission based on non-orthogonal multiple access according to claim 1, characterized in that: Allocating spectrum resources to each joint transmission cluster based on the total transmit power includes: Construct a conflict graph G = (V, ε, W), where V is the end user in all joint transmission clusters, ε is the conflict relationship between each vertex, and W is the weight of each vertex, which is represented by the optimal total transmission power of each joint transmission cluster; Finding a vertex with the largest weight in the conflict graph, and allocating a channel resource to the joint transmission cluster represented by the vertex with the largest weight; Find the neighboring vertices of the vertex with the largest weight, delete the vertex with the largest weight and its neighboring vertices, and update the conflict graph; Continue to iterate and search for the vertex with the largest weight for the updated conflict graph until the channel resources are fully allocated or all terminal users are allocated channel resources, output the mapping between all joint transmission clusters and the channel resources, and complete the spectrum resource allocation of each joint transmission cluster.

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