Anti-interference method for large-scale ad hoc network

Abstract

The invention discloses an anti-interference method for a large-scale ad hoc network, which relates to the technical field of wireless communication and comprises the following steps: S1, establishing a basic network Net1; s2, establishing P extended ad hoc networks NetP (P is a positive integer greater than or equal to 2) based on the basic network Net1; s3, respectively connecting the main node of the basic network with the main node of the extended ad hoc network through a synchronous clock line to establish an extended network; s4, selecting the synchronous frequency points M1, M2, M3... Mx (x is a positive integer) of the synchronous frequency point library of the network Net1 and the synchronous frequency points LP1, LP2, LP3... LPx of the ad-hoc network NetP according to the available frequency bands of the basic network Net1 and the extended ad-hoc network NetP, and arranging the synchronous frequency points M1, M2, M3... Mx and the synchronous frequency points LP1, LP2, LP3... LPx according to the size sequence of X; and S5, expanding the networking periodicity sequence, and selecting the synchronous frequency points of the synchronous frequency point library as the working frequency points of the respective networking in the expanded networking. According to the technical scheme provided by the invention, the network nodes of the basic networking can be expanded, and the anti-interference capability of the expanded networking can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a method for preventing interference in a large-scale ad hoc network. Background Art

[0002] TDMA is a commonly used self-organizing network technology, but as the scale of the network expands, it faces many challenges, such as decreased bandwidth utilization, increased frame length and reduced effective bandwidth due to the increase in the number of users; increased latency, increased node size and longer frame period lead to increased data transmission latency; in a strong interference environment, the TDMA system may be affected by external interference, resulting in a decrease in signal quality.

[0003] At present, the common method of large-scale networking is to access the wired network, add multiple routers or APs, connect them together to form a large-scale network, but these technologies have high requirements for networking scenarios and are often used for customized networking. Due to the free movement between nodes, dynamic adjustment of network topology cannot be achieved, and the anti-interference performance is poor. Summary of the invention

[0004] The purpose of this application is to provide a large-scale self-organizing network anti-interference method, aiming to solve the technical problem that the synchronization frequency of the frequency hopping sequence of the unmanned aerial vehicle self-organizing network cannot adapt to the time variation of the channel.

[0005] To achieve the above object, the present application proposes a method for large-scale ad hoc network anti-interference, the method comprising:

[0006] S1. Establish basic network Net1;

[0007] S2. Establish P extended ad hoc networks Net_P based on the basic network Net_1 (P is a positive integer greater than or equal to 2);

[0008] S3. Connect the master node of the basic network to the master node of the extended ad hoc network through the synchronous clock line to establish an expanded network;

[0009] S4. According to the available frequency bands of the basic network Net_1 and the extended ad hoc network Net_P, respectively establish the synchronous frequency point libraries Lib_1 and Lib_P;

[0010] S5. The expanded network periodically selects the synchronization frequencies in the synchronization frequency library as the working frequencies of the respective networks in the expanded network.

[0011] Preferably, the step S1 comprises:

[0012] A fixed working frequency Freq_1 is selected, and based on TDMA technology, the basic network main node node1, and child nodes node2, node3...nodeN (N is a positive integer greater than or equal to 2) are allocated occupied time slots t1, t2...tN and time interval t_gp.

[0013] Preferably, the step S2 comprises:

[0014] A fixed frequency Freq_P is selected, and a time interval t_gp is set. According to time slots t1, t2…tN, the main node nodeP1 and child nodes nodeP2, nodeP3, …nodePN of the ad hoc network Net_P are expanded.

[0015] Preferably, the step S2 comprises:

[0016] Freq_P is within the frequency range supported by the expanded networking.

[0017] Preferably, the step S2 comprises:

[0018] The basic network at Freq_1 and the extended ad hoc network at Freq_2, ...Ferq_P cannot interfere with each other.

[0019] Preferably, the step S4 comprises:

[0020] According to the available frequency bands of the basic network Net_1 and the extended ad hoc network Net_P, the synchronization frequencies M1, M2, M3...Mx (x is a positive integer) of the synchronization frequency library Lib_1 of the network Net1 and the synchronization frequencies L_P1, L_P2, L_P3...L_Px of the synchronization frequency library Lib_P of the ad hoc network Net_P are selected.

[0021] Preferably, the step S4 comprises:

[0022] The synchronization frequencies in the synchronization frequency library are arranged in order of size x.

[0023] Preferably, the step S4 comprises:

[0024] The frequency of the synchronization frequency point L_Px of the expanded network needs not to interfere with the frequency of the synchronization frequency point L_PX of the expanded network and the frequency of the synchronization frequency point Mx of the basic network.

[0025] One or more technical solutions proposed in this application have at least the following technical effects:

[0026] Traditional TDMA technology can only reserve new time positions by increasing the frame length. The increased frame length is FrameLen_1 (FrameLen_1>FrameLen must be satisfied), which will lead to increased latency. Expanding the node scale of the basic network is adopted to avoid latency at the same time;

[0027] Connecting the basic network with the main node of the extended network and adding a synchronous clock line to connect them can expand the network nodes of the basic network and achieve clock synchronization;

[0028] In order to increase the anti-interference capability of the expanded network, a synchronous frequency library is established and a high-speed frequency hopping strategy is introduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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 or the description of the prior art 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 the structures shown in these drawings without paying creative work.

[0030] Figure 1 It is a flow chart of a method for large-scale ad hoc network anti-interference according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of time slot allocation for expanding one networking network node according to an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of a network topology for expanding a network according to an implementation of the present invention;

[0033] Figure 4 This is a schematic diagram of time slot allocation for expanding P networking nodes according to an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of a network topology for expanding P networking groups according to an implementation of the present invention;

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] 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.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] The invention discloses a large-scale self-organizing network anti-interference method, aiming to solve the technical problem of low anti-interference in a self-organizing network system based on TDMA.

[0040] Embodiment 1

[0041] like Figure 1 As shown in the flowchart of a method for large-scale self-organizing network anti-interference, in order to solve the technical problem that the synchronization frequency of the frequency hopping sequence of the unmanned aerial vehicle self-organizing network using the frequency hopping mode cannot adapt to the time variation of the channel, this embodiment provides a method for large-scale self-organizing network anti-interference, including the following steps:

[0042] S1. Establish basic networking based on TDMA technology;

[0043] In the ad hoc networking system, TDMA is a classic networking method that allows multiple users to use the same frequency in different time slices (time slots). In the fixed time slot allocation mode, this technology implements networking by allocating fixed time slots to each communication participant in the network planning stage. It is also the basic method for the present invention to achieve large-scale networking. The fixed time slot allocation strategy is a stable network resource allocation strategy, which is also the networking strategy adopted by the present invention, including:

[0044] Select an operating frequency (Freq_1) based on the frequency band range supported by the radio frequency module of the basic networking hardware equipment, that is, all nodes must work at the fixed frequency of Freq_1.

[0045] Determine the node scale of the basic network (N, that is, the total number of nodes, usually not more than 100. Under TDMA, too large a node scale will lead to reduced bandwidth utilization and increased latency, etc.), such as Figure 2 As shown in the schematic diagram of network node time slot allocation for expanded networking, N nodes are numbered from the main node node1 to the child node node2,...nodeN, and the corresponding nodes are allocated occupied time slots t1, t2...tN and time intervals t_gp. Adding up all the time is the frame length FrameLen (FrameLen = t1+t_gp+t2+t_gp+t3+t_gp+....+tN+t_gp).

[0046] When the frame length FrameLen is determined, the maximum one-way delay of each device is FrameLen. In the extreme case, according to Figure 2 , assuming that the data arrives at node1 at the end of time t1, it is necessary to wait for the next cycle, that is, FrameLen, before the data can be transmitted.

[0047] Under the frame length FrameLen, the maximum node size is N. Nodes beyond the range of node N can no longer be allocated time slot resources. The only way is to increase the frame length to reserve a new time position. The increased frame length is FrameLen_1 (FrameLen_1>FrameLen must be satisfied), which will lead to an increase in latency. Therefore, it is necessary to adopt a method that avoids latency while expanding the node size of the basic network.

[0048] S2. Expand the node scale of basic networking;

[0049] TDMA's fixed time slot allocation strategy has achieved a node scale within the range of less than or equal to N. Since the above strategy uses the same frequency Freq_1 communication, that is, the spectrum is fixed and the total frame length is constant, in order to avoid data transmission delays caused by expanding the node scale in the basic networking, the frequency Freq_2 is used, and the same allocation strategy is used to achieve a node scale of N nodes, that is, a node scale of 2N is achieved, that is, an extended ad hoc network.

[0050] The selection of the frequency Ferq_2 needs to meet the following requirements:

[0051] 1. Both Freq_1 and Freq_2 are within the frequency range supported by the expanded network;

[0052] 2. The basic network cannot interfere with each other at Freq_1 and the extended ad hoc network at Freq_2 (the selection of frequency needs to be determined in combination with the RF performance of the specific equipment), that is, the basic network and the extended ad hoc network can send and receive at the same time at Freq_1 and Freq_2, and the sensitivity between them is not affected;

[0053] 3. Such as Figure 2 As shown in the diagram of the network node time slot allocation of the expanded network, the time allocation of node21 under Freq_2 must be the same as the time allocation of node1 under Freq_1 (both are t1), and the time allocation of node22 under Freq_2 must be the same as the time allocation of node2 under Freq_1 (both are t2); ....; the time allocation of node2N under Freq_2 must be the same as the time allocation of nodeN under Freq_1 (both are tN). That is, the extended self-organizing network node numbers under Freq_2 frequency are: node21, node22, node23, ....node2N;

[0054] Since the frequency Freq_1 and the frequency Freq_2 do not affect each other, the two frequency groups each form two independent networks. Select the main nodes: node1 and node21 as two ground station nodes (ground station nodes are usually placed in a fixed position on the ground), such as Figure 3 As shown in the network topology diagram of expanding one network, the network ports of node1 and node21 are connected to the same network switch, and then the interaction with external data is realized through other idle network ports of the network switch, thus realizing the expansion of the basic network.

[0055] S3. Use the clock synchronization line to align the clocks of the two networks;

[0056] Although the two groups of networks in step 2 have achieved data intercommunication through the network switch, the two groups of nodes are not unified in the time dimension in a macro sense, that is, the corresponding node2+1 may not be at the same time when node1 transmits, but may be node22, node23, etc., or even in a certain t_gp time period, which is completely uncontrollable. In order to synchronize the transmission and reception of the two groups of networks, the clocks of the master nodes of the two groups of networks need to be aligned.

[0057] Node 1 is set as the master node, and node 21 is set as the master-slave node. Whenever time 0 of the frame cycle of the master node arrives (i.e., the start time t1), a pulse signal is output through the clock alignment line.

[0058] Node21 continuously obtains pulse signals from the node and sets its own (node21) time position to time 0, thereby achieving time synchronization between node1 and node21, and then achieving full network alignment through their respective group networks.

[0059] S4. Select the synchronization frequency of each network according to the available frequency band of the self-organizing network;

[0060] The basic network and the extended network use a fixed frequency method. Although this method is relatively stable, it lacks certain anti-interference capabilities. When the frequency is interfered with, the entire network will be paralyzed. In order to increase the anti-interference capability of the network, a high-speed frequency hopping strategy is introduced, so it is necessary to establish a frequency hopping synchronization library.

[0061] According to the available frequency bands of the basic network Net_1 and the extended ad hoc network Net_2, the synchronization frequency points M1, M2, M3...Mx (X is a positive integer) of the ad hoc network Net_1 are selected to form the synchronization frequency point library of the original ad hoc network Net_1, and the synchronization frequency points L_21, L_22, L_23...L_2x of the ad hoc network Net_2 are selected to form the synchronization frequency point library of the extended ad hoc network Net_2, and the synchronization frequency points are arranged in the order of X;

[0062] At the same time, the frequencies of the sequential synchronization frequency points Mx and L_2X in the candidate synchronization frequency point library must be kept from interfering with each other.

[0063] S5. Periodically select the synchronization frequency as the working frequency of each network in the expanded network;

[0064] Since the synchronization clock line is added, it can be ensured that node1 works at the M1 frequency at time t0 (nodeN belongs to the child node of the basic network, so it also works at the M1 frequency), and node1+1 also works at the L_21 frequency at time t0 ((node2+N ​​belongs to the child node of the basic network, so it also works at the M1 frequency)).

[0065] That is, when the two ad hoc networks (basic and extended ad hoc networks) are working, the corresponding nodes nodeN and node1+N select the corresponding synchronization frequencies Mx and L_2x (starting from X=1) as the working frequencies in a periodic sequence according to the time interval tN (starting from time t0) (selected in a periodic sequence, that is, after the synchronization frequencies are selected in the order of size X, they are selected again from X1).

[0066] Example 2

[0067] This embodiment provides a method for large-scale ad hoc network anti-interference, including the following steps:

[0068] S1. Establish basic networking based on TDMA technology;

[0069] In the ad hoc networking system, TDMA is a classic networking method that allows multiple users to use the same frequency in different time slices (time slots). In the fixed time slot allocation mode, this technology implements networking by allocating fixed time slots to each communication participant in the network planning stage. It is also the basic method for the present invention to achieve large-scale networking. The fixed time slot allocation strategy is a stable network resource allocation strategy, which is also the networking strategy adopted by the present invention, including:

[0070] Select an operating frequency (Freq_1) based on the frequency band range supported by the radio frequency module of the basic networking hardware equipment, that is, all nodes must work at the fixed frequency of Freq_1.

[0071] Determine the node scale of the basic network (N is the total number of nodes, usually not more than 100. Under TDMA, a large node scale will lead to a decrease in bandwidth utilization and an increase in latency, etc.), number the N nodes, from the main node node1 to the child node node2,...nodeN, and allocate the occupied time slots t1, t2...tN and the time interval t_gp to the corresponding nodes. Adding up all the time is the frame length FrameLen (FrameLen=t1+t_gp+t2+t_gp+t3+t_gp+....+tN+t_gp).

[0072] Under the frame length FrameLen, the maximum node size is N. Nodes beyond the range of node N can no longer be allocated time slot resources. The only way is to increase the frame length to reserve a new time position. The increased frame length is FrameLen_1 (FrameLen_1>FrameLen must be satisfied), which will lead to an increase in latency. Therefore, it is necessary to adopt a method that avoids latency while expanding the node size of the basic network.

[0073] S2. Expand the node scale of basic networking;

[0074] The fixed time slot allocation strategy of TDMA has achieved the node scale within the range of less than or equal to N. Since the above strategy uses the same frequency Freq_1 communication, that is, the spectrum is fixed and the total frame length is constant, in order to avoid data transmission delay caused by expanding the node scale in the basic network, other (P-1) frequencies Freq_P are used, such as Figure 5 As shown in the schematic diagram of network node time slot allocation in an embodiment of expanding P networking, the same allocation strategy is used to achieve a node scale of N nodes, that is, a node scale of N*P is achieved, that is, (P-1) extended ad hoc networks are established.

[0075] The selection of the frequency Ferq_P (P is a positive integer greater than or equal to 2) needs to meet the following requirements:

[0076] 1. Freq_P is within the frequency range supported by the expanded network (basic network and extended ad hoc network);

[0077] 2. The basic network at Freq_1 and the extended ad hoc network at Freq_2, ...Ferq_P cannot interfere with each other (need to be determined in combination with the RF performance of the specific equipment), that is, Freq_1, Freq_2, ...Ferq_P can send and receive at the same time and the sensitivity between them is not affected;

[0078] The time allocation of nodeN+1 under Freq_P must be the same as the time allocation of node1 under Freq_1 (both are t1), the time allocation of nodeP+2 under Freq_P must be the same as the time allocation of node2 under Freq_1 (both are t2); ....; the time allocation of nodePN under Freq_P must be the same as the time allocation of nodeN under Freq_1 (both are tN).

[0079] That is, the nodes of the extended ad hoc network at the frequency Freq_P are numbered as: nodeP1, nodeP2, nodeP3, ....nodePN.

[0080] Since the frequencies Freq_1, Freq_2…Freq_P do not affect each other, the two frequency groups each form P independent networks. Select the main nodes: node1, node21,…nodeP1 as ground station nodes (ground station nodes are usually placed in a fixed position on the ground), and connect the network ports of node1, node21,…nodeP1 to the same network switch, and then interact with external data through other idle network ports of the network switch, thus realizing the expansion of the basic network.

[0081] S3. Use the clock synchronization line to align the clocks of the two networks;

[0082] Although the self-organizing networks in step 2 have achieved data intercommunication through the network switch, the time dimension of the self-organizing network nodes is not uniform in the macro sense, that is, when node1 transmits, the corresponding node21 may not be at the same time, but may be nodeP2, nodeP3, etc., or even in a certain t_gp time period, which is completely uncontrollable. In order to synchronize the transmission and reception of the two networks, the master nodes of the two networks need to be clock-aligned.

[0083] like Figure 5As shown in the network topology diagram of P networks, node1, ..., node(P-1)1, and nodeP1 are set as master nodes and connected using a clock synchronization line. Whenever time 0 of the master node's frame cycle arrives (i.e., the start time t1), a pulse signal is output through the clock alignment line.

[0084] NodeP1 continuously obtains pulse signals from the node and sets its own nodeP1 time position to time 0, thereby achieving time synchronization between node1 and nodeP1, and then achieving full network alignment through their respective group networks.

[0085] S4. Select the synchronization frequency of each network according to the available frequency band of the self-organizing network;

[0086] Each networking device uses a fixed frequency method, which is relatively stable, but lacks certain anti-interference capabilities. When the frequency is interfered with, the entire network will be paralyzed. In order to increase the anti-interference capability of the network, a high-speed frequency hopping strategy is introduced, so it is necessary to select a synchronous frequency point library for frequency hopping.

[0087] According to the available frequency bands of the basic network Net_1 and the extended ad hoc network Net_P, establish the synchronization frequency point library Lib_1 and Lib_P respectively; select the synchronization frequency points M1, M2, M3...Mx (X is a positive integer) of the basic network Net1 to form the synchronization frequency point library Lib_1 of the basic network Net_1 and the synchronization frequency points L_P1, L_P2, L_P3...L_Px of the ad hoc network Net_2 to form the synchronization frequency point library Lib_P of the extended ad hoc network Net_P, and the synchronization frequency points are arranged in order of size x;

[0088] At the same time, the frequencies of the sequential synchronization frequency points Mx and L_PX in the candidate synchronization frequency point library must be kept from interfering with each other.

[0089] S5. Periodically select the synchronization frequency as the working frequency of each network in the expanded network;

[0090] Since the synchronization clock line is added, it can be ensured that node1 works at the M1 frequency at time t0 (nodeN belongs to the child node of the basic network, so it also works at the M1 frequency), and nodeP1 also works at the L_P1 frequency at time t0 (nodePN belongs to the child node of the basic network, so it also works at the M1 frequency).

[0091] That is, when the expanded network (basic and extended ad hoc network) is working, the corresponding nodes, for example: nodeN, node(P-1)N and nodePN, respectively select the corresponding synchronization frequency points Mx, L_Px and L_Px (starting from x=1) as the working frequency points in a periodic sequence according to the time interval tN (starting from time t0) (selected in periodic sequence, that is, after the synchronization frequency points are selected in order of size x, they are selected again from x1).

[0092] It can be seen from the above embodiments that the present application dynamically adjusts the synchronization frequency point used in the current cycle according to the channel quality, thereby solving the problem of data loss due to interference with the synchronization frequency point;

[0093] When the node fails to switch the synchronous frequency, the node continuously adjusts its own frequency to re-network with other nodes, thereby improving the dynamic adjustment capability of the node.

[0094] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for large-scale ad hoc network anti-interference, characterized in that: The method comprises: S1. Establish basic network Net1; S2. Establish P extended ad hoc networks Net_P based on the basic network Net_1 (P is a positive integer greater than or equal to 2); S3. Connect the master node of the basic network to the master node of the extended ad hoc network through the synchronous clock line to establish an expanded network; S4. According to the available frequency bands of the basic network Net_1 and the extended ad hoc network Net_P, respectively establish the synchronous frequency point libraries Lib_1 and Lib_P; S5. The expanded network periodically selects the synchronization frequencies in the synchronization frequency library as the working frequencies of the respective networks in the expanded network.

2. A large-scale ad hoc network anti-interference method as claimed in claim 1, characterized in that: The step S1 comprises: A fixed working frequency Freq_1 is selected, and based on TDMA technology, the basic network main node node1, and child nodes node2, node3...nodeN (N is a positive integer greater than or equal to 2) are allocated occupied time slots t1, t2...tN and time interval t_gp.

3. A large-scale ad hoc network anti-interference method as claimed in claim 1, characterized in that: The step S2 comprises: A fixed frequency Freq_P is selected, and a time interval t_gp is set. According to time slots t1, t2…tN, the main node nodeP1 and child nodes nodeP2, nodeP3, …nodePN of the ad hoc network Net_P are expanded.

4. A large-scale ad hoc network anti-interference method as claimed in claim 3, characterized in that: The step S2 comprises: Freq_P is within the frequency range supported by the expanded networking.

5. A large-scale ad hoc network anti-interference method as claimed in claim 3, characterized in that: The step S2 comprises: The basic network at Freq_1 and the extended ad hoc network at Freq_2, ...Ferq_P cannot interfere with each other.

6. A large-scale ad hoc network anti-interference method as claimed in claim 1, characterized in that: The step S4 comprises: According to the available frequency bands of the basic network Net_1 and the extended ad hoc network Net_P, the synchronization frequencies M1, M2, M3...Mx (x is a positive integer) of the synchronization frequency library Lib_1 of the network Net1 and the synchronization frequencies L_P1, L_P2, L_P3...L_Px of the synchronization frequency library Lib_P of the ad hoc network Net_P are selected.

7. A large-scale ad hoc network anti-interference method as claimed in claim 6, characterized in that: The step S4 comprises: The synchronization frequencies in the synchronization frequency library are arranged in order of size x.

8. A large-scale ad hoc network anti-interference method as claimed in claim 6, characterized in that: The step S4 comprises: The frequency of the synchronization frequency point L_Px of the expanded network does not interfere with the frequency of the expanded network L_PX and the frequency of the synchronization frequency point Mx of the basic network.

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