A non-orthogonal multiple access transmission method suitable for a hybrid network of short and long data packets

Abstract

The present invention discloses a non-orthogonal multiple access transmission method suitable for a mixed network of short data packets and long data packets, comprising: a sending node, multiple short data packet users and a long data packet user, the sending node is equipped with multiple antennas, and other nodes are all equipped with single antennas; the data packets of the short data packet users and the long data packet users share the same communication resource by using non-orthogonal multiple access technology to improve resource utilization efficiency; the short data packet users have a higher priority, and their packet error rate needs to be ensured to be below the required threshold, and after the communication needs of the short data packet users are met, the transmission efficiency of the long data packet users is improved as much as possible; the present invention takes three Internet of Things scenarios into consideration, designs corresponding resource allocation methods, and verifies the superiority of the designed method compared with the traditional orthogonal transmission method, improves the utilization efficiency of network resources, increases the number of network connections, and is suitable for large-scale Internet of Things wireless communications.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communication, and particularly to a non-orthogonal multiple access transmission method applicable to a mixed network of short data packet and long data packet communications in the Internet of Things. Background Art

[0002] The Internet of Things aims to provide ubiquitous connections, connecting all aspects of life and production into a unified network. With the continuous advancement of 5G wireless communication, although the Internet of Things has developed rapidly, there are still technical bottlenecks to be broken through. On the one hand, it is a great challenge to achieve large-scale connections under limited resource constraints. On the other hand, the different communication requirements of numerous devices make the network very complex. Non-orthogonal Multiple Access (NOMA) technology re-partitions wireless communication resources in the power domain, enabling multiple users to share the same communication resources, and is particularly suitable for communication scenarios with large differences in user channels and communication requirements. NOMA is considered to be one of the potential technologies for increasing the number of network users and spectrum utilization rate in the future wireless communication field, and is expected to meet the large-scale connection requirements under resource constraints in the Internet of Things. In addition, using a scientific resource allocation method can enable the orderly and efficient transmission of signals with different communication requirements. Fully considering the characteristics of short data communication in the Internet of Things and designing a reasonable resource allocation method to make full and efficient use of communication resources is the key to improving the communication ability of the Internet of Things.

[0003] Using NOMA technology to group and transmit the information of short data packet users and long data packet users, with superposition coding at the sending end and successive interference cancellation technology at the receiving end, can achieve the reuse of the same communication resources by short data packet users and long data packet users. There is a small amount of research on the way of using NOMA to group and transmit the information of short data packet users and long data packet users in the existing literature. However, since it does not consider the resource constraints in the Internet of Things and lacks lightweight design, it cannot be directly used in the Internet of Things. Summary of the Invention

[0004] In view of the two major requirements of short data packet communication and long data packet communication in the Internet of Things, and considering the actual situation of resource constraints, the present invention designs a non-orthogonal multiple access transmission method applicable to a mixed network of short data packet and long data packet communications, and improves the transmission efficiency of long data packet users on the premise of meeting the packet error rate of short data packet users.

[0005] The technical solution of the present invention is: a non-orthogonal multiple access transmission method applicable to a mixed network of short data packets and long data packets, which includes: a sending node S, I short data packet users i, i ∈ {1, 2, …, I}, and a long data packet user j. The sending node S is equipped with K antennas, and other nodes are all configured with single antennas, and all work in the half-duplex mode; the data packets of the short data packet users and the long data packet user share the same communication resource by using NOMA. The short data packet users have priority, and their packet error rates are ensured to be below the threshold ε. t After the communication requirements of the short data packet users are met, the transmission efficiency of the long data packet user is improved; the transmission method includes the following steps: the first step is to select a resource allocation method; the second step is to transmit signals according to the selected resource allocation method; the third step is to receive and demodulate signals according to the selected resource allocation method.

[0006] Further, the resource allocation methods are: resource allocation method one, resource allocation method two, and resource allocation method three, that is, the resource allocation method under normal fading conditions, the resource allocation method under general fading conditions, and the resource allocation method under deep fading conditions. The three resource allocation methods are used to deal with different fading conditions of the short data packet users.

[0007] Further, the selection method of the three resource allocation methods is as follows: The sending node S first defaults to select resource allocation method two. Under this method, the feedback information of the short data packet users is used to determine whether the packet error rate requirement of the short data packet users is met. If it is met, the sending node S tries to adopt resource allocation method one and determines whether the packet error rate requirement of the short data packet users is met. If it is met, resource allocation method one is determined to be used; if not, resource allocation method two is determined to be used; if resource allocation method two cannot meet the packet error rate requirement of the short data packet users, then resource allocation method three is finally selected. If resource allocation method three also cannot meet the packet error rate requirement of the short data packet users, the communication fails.

[0008] Further, resource allocation method one includes the allocation of antenna resources and power resources; this resource allocation method is to allocate antenna resources to the long data packet user and improve the communication rate of the long data packet user as much as possible under the condition of meeting the reliability requirements of the short data packet users.

[0009] Further, resource allocation method two includes the allocation of antenna resources and power resources; this resource allocation method is to allocate antenna resources to the short data packet users and improve the communication rate of the long data packet user as much as possible under the condition of meeting the reliability requirements of the short data packet users.

[0010] Furthermore, the third resource allocation method includes the allocation of antenna resources, power resources, and transmission time slots; this power allocation is for the scenario of deep fading. Each short data packet user cooperates with each other. After any data packet is demodulated, it is broadcast to each user. Since the users are clustered and close to each other, the broadcast signal can be correctly received by each short data packet user; under the condition of first satisfying the packet error rate of each short data packet user, the communication rate of the long data packet user is improved as much as possible.

[0011] The advantages of the present invention are as follows:

[0012] 1. The applicable scope is to meet different communication requirements in the Internet of Things, especially for the cases with high requirements for transmission delay, reliability, and efficiency, where long data packet and short data packet communications coexist. By using the non-orthogonal multiple access method, the utilization efficiency of network resources is improved to meet the large-scale connection requirements of the Internet of Things.

[0013] 2. For three Internet of Things scenarios, corresponding resource allocation methods are designed, and the superiority of the three resource allocation methods over the traditional orthogonal multiple access technology is verified.

[0014] 3. The data packets of short data packet users and long data packet users share the same communication resources by using NOMA to improve the resource utilization efficiency.

[0015] 4. Short data packet users have a higher priority, and their packet error rate is ensured to be below the threshold ε t When the communication requirements of short data packet users are met, the transmission efficiency of long data packet users is improved as much as possible.

[0016] 5. Through resource allocation, after first satisfying the information reliability requirements of short data packet users, the transmission efficiency of long data packet users is improved as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments of the present invention. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a non-orthogonal multiple access transmission model diagram applicable to a hybrid network of short data packet and long data packet communications provided by an embodiment of the present invention;

[0019] Figure 2 It is a flowchart for selecting the resource allocation method of the present invention;

[0020] Figure 3It shows the graph of the effective transmission rate of the duration packet user varying with the transmission power when using Resource Allocation Method 1 under ordinary fading conditions;

[0021] Figure 4 It shows the graph of the effective transmission rate of the duration packet user varying with the transmission power when using Resource Allocation Method 2 under general fading conditions;

[0022] Figure 5 It shows the graph of the effective transmission rate of the duration packet user varying with the transmission power when using Resource Allocation Method 3 under deep fading conditions. Specific Embodiment

[0023] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0024] Next, the technical solutions of the present invention will be described in detail in combination with the accompanying drawings.

[0025] As Figure 1 shown, a non-orthogonal multiple access transmission method applicable to a mixed network of short-packet and long-packet communications includes: a transmitting node S, I short-packet users i, i ∈ {1, 2,..., I}, and a long-packet user j. The transmitting node S is equipped with K antennas, and other nodes are all configured with single antennas. All operate in the half-duplex mode; the length of the long packet is L, the length of the short packet is N, and I = L / N; the channel from the transmitting node S to the short-packet user is defined as h i , and the channel from the transmitting node S to the long-packet user j is defined as h j ; the packets of the short-packet users and the long-packet user share the same communication resource using NOMA to improve the resource utilization efficiency; the short-packet users have a higher priority, and their packet error rate is ensured to be below the threshold ε t ; after meeting the communication requirements of the short-packet users, the transmission efficiency of the long-packet user is improved as much as possible; this solution designs resource allocation methods under ordinary fading conditions, general fading conditions, and deep fading conditions. The three resource allocation methods are used to deal with different fading situations of the short-packet users, and are respectively denoted as Resource Allocation Method 1, Resource Allocation Method 2, and Resource Allocation Method 3.

[0026] Among them, the specific implementation process of the transmission method is as follows:

[0027] Step 1, select the resource allocation method: The sending node S initially defaults to selecting resource allocation method 2. Under this method, it uses the feedback information of the short-packet users to determine whether the packet error rate requirement of the short-packet users is met. If it is met, the sending node S attempts to adopt resource allocation method 1 and determines whether the packet error rate requirement of the short-packet users is met. If it is met, it determines to use resource allocation method 1; if not, it determines to use resource allocation method 2; if resource allocation method 2 cannot meet the packet error rate requirement of the short-packet users, it finally selects resource allocation method 3. If resource allocation method 3 also cannot meet the packet error rate requirement of the short-packet users, the communication fails;

[0028] As Figure 2 shown in the resource allocation method selection flowchart, the specific implementation methods of the three resource allocation methods are as follows:

[0029] I. Resource allocation method 1 includes the allocation of antenna resources and power resources

[0030] The sending node S performs beamforming on the long-packet users using the beamforming factor w, and uses the superposition coding method to send the information required by the two users. The signals received by the short-packet user i and the long-packet user j are respectively

[0031]

[0032] P is the transmission power, x s ={x 1 ,…x i ,…x I} is the data sent to the short-packet user, x j is the data sent to the long-packet user, α s ,α j are respectively the power allocation factors of the short-packet user and the long-packet user, n i ,n j are respectively the Gaussian white noise at the short-packet user i and the long-packet user j, with a variance of σ 2 ;

[0033] The signal-to-interference-plus-noise ratio for the short-packet user to demodulate its target information x i is

[0034]

[0035] The signal-to-interference-plus-noise ratio for the long-packet user to perform successive interference cancellation is

[0036]

[0037] When the long-packet user accurately performs successive interference cancellation, the signal-to-noise ratio for it to demodulate the target signal is

[0038]

[0039] Prioritize meeting the packet error rate of each short data packet user and improve the communication rate of long data packet users as much as possible. The power allocation coefficient satisfies

[0040]

[0041] V(x) = 1 - (1 + x) -2 , where B is the number of information bits of the short data packet user's information, and ε h is the error threshold of successive interference cancellation; this power allocation method uses the statistical packet error rate as the design index, avoiding the additional overhead brought by real-time channel estimation, and is suitable for the communication scenarios with limited resources in the Internet of Things;

[0042] Under this resource allocation method, the effective transmission rate of the long data packet user is

[0043] η = R Pr[γ j > 2 R -1, Φ] (7)

[0044] R is the transmission rate of the long data packet user, and Φ indicates that all interference has been cancelled by successive interference cancellation;

[0045] This resource allocation method allocates antenna resources to long data packet users and improves the communication rate of long data packet users as much as possible while meeting the reliability requirements of short data packet users;

[0046] II. Resource Allocation Method 2 includes the allocation of antenna resources and power resources

[0047] The sending node S performs beamforming on the short data packet users using the beamforming factor w, and uses superposition coding to send the information required by both users. The signals received by the short data packet user i and the long data packet user j are respectively

[0048]

[0049] P is the transmission power, and x s = {x 1 ,…x i ,…x I} is the data sent to the short data packet user, and x j is the data sent to the long data packet user. α s ,α j are the power allocation factors of the short data packet user and the long data packet user respectively, and n i ,n j are the Gaussian white noises at the short data packet user i and the long data packet user j respectively, with a variance of σ 2 ;

[0050] The short-packet user demodulates its destination information x i The signal-to-interference-plus-noise ratio of is

[0051]

[0052] The signal-to-interference-plus-noise ratio for the long-packet user to perform successive interference cancellation is

[0053]

[0054] When the long-packet user accurately performs successive interference cancellation, the signal-to-noise ratio of its demodulated destination signal is

[0055]

[0056] Give priority to satisfying the packet error rate of each short-packet user, and improve the communication rate of the long-packet user as much as possible. The power allocation coefficient satisfies

[0057]

[0058] V(x) = 1 - (1 + x) -2 , B is the number of information bits of the short-packet user information, ε h is the error threshold of successive interference cancellation; this power allocation method uses the statistical packet error rate as the design index to avoid the additional overhead caused by real-time channel estimation, and is suitable for the communication scenario with limited resources in the Internet of Things;

[0059] Under this resource allocation method, the effective transmission rate of the long-packet user is

[0060] η = R Pr[γ j > 2 R -1, Φ] (14)

[0061] R is the transmission rate of the long-packet user, and Φ indicates that all interference has been cancelled by successive interference cancellation;

[0062] This resource allocation method allocates antenna resources to short-packet users and improves the communication rate of long-packet users as much as possible while meeting the reliability requirements of short-packet users;

[0063] III. Resource allocation method three includes the allocation of antenna resources, power resources, and transmission time slots

[0064] The sending node S uses the beamforming factor w to perform beamforming on the user with the best signal among the short-packet users, and uses superposition coding to send the information required by the two users. The signals received by the short-packet user i and the long-packet user j are respectively

[0065]

[0066] P is the transmit power, x s ={x 1 ,…x i ,…x I} is the data sent to the short data packet user, x j is the data sent to the long data packet user, α s ,α j Respectively, the power allocation factors for short data packet users and long data packet users, n i ,n j are Gaussian white noises at short data packet user i and long data packet user j, with variance σ 2 ;

[0067] Short data packet user demodulates its destination information x i The signal-to-interference-to-noise ratio of is

[0068]

[0069] The signal-to-noise ratio for serial interference cancellation for long data packet users is

[0070]

[0071] When the long data packet user accurately performs serial interference elimination, the signal-to-noise ratio of the demodulated target signal is

[0072]

[0073] This power allocation method can cope with the deep fading scenario. Each short data packet user cooperates with each other. When any data packet is demodulated, it is broadcast to each user. Since the users are distributed in clusters, the broadcast signal can be correctly received by each short data packet user. While giving priority to satisfying the packet error rate of each short data packet user and maximizing the communication rate of the long data packet user, the power allocation coefficient meets

[0074]

[0075] V(x)=1-(1+x) -2 , B is the number of information bits of the user information of the short data packet, ε h is the error threshold for serial interference elimination; this power allocation method uses the statistical packet error rate as a design indicator to avoid the additional overhead caused by real-time channel estimation, and is suitable for communication scenarios with limited IoT resources;

[0076] Under this resource allocation method, the effective transmission rate of long data packet users is

[0077] η=R Pr[γ j >2 R-1, Φ] (21)

[0078] R is the transmission rate of long packet users, and Φ indicates that all interference is eliminated by successive interference cancellation;

[0079] This resource allocation method allocates antenna resources to short packet users, and uses the cooperation of short packets to achieve reliable communication in deep fading scenarios, and improves the communication rate of long packet users as much as possible while meeting the reliability requirements of short packet users;

[0080] Step 2: Transmit signals according to the selected resource allocation method;

[0081] Step 3: Receive and demodulate signals according to the selected resource allocation method.

[0082] The transmission method of the present invention is compared with the traditional orthogonal transmission method, and the simulation results are as Figure 3 , Figure 4 and Figure 5 shown.

[0083] Figure 3 It represents the graph of the effective transmission rate of long packet users changing with the transmission power when using Resource Allocation Method 2 under normal fading conditions, where the total packet length L = 30000, the short packet length N = 200, the number of antennas K = 4, the packet error threshold ε t = 0.0001, ε h = 0.001, the long packet target rate R = 3 bit, the channel fading mean E[|h i | 2 = -110 dB, E[|h j | 2 = -110 dB.

[0084] Figure 4 It represents the graph of the effective transmission rate of long packet users changing with the transmission power when using Resource Allocation Method 2 under general fading conditions, where the total packet length L = 30000, the short packet length N = 200, the number of antennas K = 4, the packet error threshold ε t = 0.0001, ε h = 0.001, the long packet target rate R = 3 bit, the channel fading mean E[|h i | 2 = -125 dB, E[|h j | 2 = -110 dB.

[0085] Figure 5It shows the graph of the effective transmission rate of long data packet users varying with the transmission power when using Resource Allocation Method 3 under deep fading conditions, where the total length of the data packet L = 30000, the length of the short data packet N = 200, the number of antennas K = 4, the packet error threshold ε t = 0.0001, ε h = 0.001, the target rate of the long data packet R = 3 bit, the mean value of channel fading E[|h i | 2 = -135 dB, E[|h j | 2 = -110 dB.

[0086] From Figure 3 , Figure 4 and Figure 5 it can be seen that for the transmission method designed in this scheme, under the three conditions of normal fading, general fading and deep fading, excellent transmission performance can be achieved compared with the traditional orthogonal transmission method, verifying the superiority of this method.

Claims

1. A non-orthogonal multiple access transmission method suitable for a mixed network of short data packets and long data packets, characterized in that: The hybrid network includes: a sending node, multiple short data packet users, and a long data packet user, and the sending node is equipped with K The transmission node, the short data packet user and the long data packet user are all configured with a single antenna, and the sending node, the short data packet user and the long data packet user all work in half-duplex mode; the data packets of the short data packet user and the long data packet user share the same communication resource using NOMA, the short data packet user has a high priority relative to the long data packet user, and its packet error rate is guaranteed to be below the threshold, and after the communication needs of the short data packet user are met, the transmission efficiency of the long data packet user is improved; the transmission method comprises the following steps: the first step is to select a resource allocation method; the second step is to transmit a signal according to the selected resource allocation method; the third step is to receive and demodulate according to the selected resource allocation method signal; the resource allocation modes include: resource allocation mode 1, resource allocation mode 2 and resource allocation mode 3, namely, the resource allocation mode under normal fading, the resource allocation mode under general fading and the resource allocation mode under deep fading, and the three resource allocation modes correspond to different fading conditions of short data packet users; the selection method of the three resource allocation modes is as follows: the sending node first selects resource allocation mode 2 by default, under which the feedback information of the short data packet user is used to determine whether the packet error rate requirement of the short data packet user is met, and if so, the sending node tries to use resource allocation mode 1 to determine whether the packet error rate requirement of the short data packet user is met If the requirement is met, resource allocation method 1 is used; if not, resource allocation method 2 is used; if resource allocation method 2 cannot meet the packet error rate requirement of the short data packet user, resource allocation method 3 is finally selected; if resource allocation method 3 also cannot meet the packet error rate requirement of the short data packet user, communication fails; the resource allocation method 1 includes the allocation of antenna resources and power resources; the resource allocation method 1 allocates antenna resources to long data packet users and improves the communication rate of long data packet users as much as possible while meeting the reliability requirement of short data packet users; the resource allocation method 2 includes the allocation of antenna resources and power resources; the resource allocation method 3 includes the allocation of antenna resources and power resources; The second allocation method is to allocate antenna resources to short data packet users, and to increase the communication rate of long data packet users as much as possible while meeting the reliability requirements of short data packet users; the resource allocation method three includes the allocation of antenna resources, power resources and transmission time slots; this resource allocation method three corresponds to the scenario of deep fading, each short data packet user cooperates with each other, and when any short data packet is demodulated, it is broadcast to each short data packet user. Since short data packet users are distributed in clusters and are close to each other, the broadcast signal can be correctly received by each short data packet user; while giving priority to meeting the packet error rate of each short data packet user, the communication rate of long data packet users is increased as much as possible.

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