Access synchronization and tracking method for TDMA ad hoc network broadband frequency hopping system

Abstract

This invention relates to a method for access synchronization and tracking of broadband frequency-hopping systems in TDMA ad hoc networks, belonging to the field of communication technology. This invention solves the problem that existing methods cannot achieve synchronization and access of broadband frequency-hopping systems in TDMA ad hoc network scenarios. In this invention, frequency-hopping time slots are correlated with TDMA ad hoc network time slots. By completing the time synchronization and tracking correction process of the TDMA ad hoc network, the synchronization acquisition and tracking of the frequency-hopping system are simultaneously completed, making the network access process simpler and faster. Through the synchronization symbols carried within each time slot, the receiver can accurately determine the position of each symbol, complete signal demodulation, and realize information transmission. Simultaneously, the design of the front and rear guard intervals can effectively cope with the impact of different clock deviations and propagation delays during interconnection between nodes in the ad hoc network. This invention can be applied to the synchronization and access of broadband frequency-hopping systems in TDMA ad hoc network scenarios.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically relating to a method for access synchronization and tracking in a TDMA self-organizing network broadband frequency hopping system. Background Technology

[0002] With the increasing demand for various high-speed communication services, broadband communication technologies, such as the representative broadband OFDM technology, are being used more and more widely in wireless communication systems. In military communication scenarios, communication systems not only need to meet high communication speed requirements but also need to counter various malicious interferences from the enemy in complex battlefield environments. Frequency hopping technology, as an effective means of combating interference, is also widely used in various military communication systems. Simultaneously, with the application of UAV swarms in the military, the endpoints of military communication networks are increasingly required to possess strong network self-organization capabilities and robust network topology. However, existing methods still cannot achieve synchronization and access for broadband frequency hopping systems in TDMA self-organizing network scenarios. Summary of the Invention

[0003] The purpose of this invention is to address the problem that existing methods cannot achieve synchronization and access in broadband frequency-hopping systems within TDMA ad hoc network scenarios. Therefore, this invention proposes a method for access synchronization and tracking of broadband frequency-hopping systems in TDMA ad hoc networks. Specifically, the broadband frequency-hopping system described in this invention refers to a broadband communication system that incorporates frequency-hopping technology, based on a broadband communication system, where the communication frequency continuously changes during communication.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0005] A method for access synchronization and tracking in a TDMA self-organizing network broadband frequency hopping system, the method specifically includes the following steps:

[0006] Step 1: Pre-set M frequency hopping tables, and each frequency hopping table contains several frequency points, the duration of each frequency point is t. hop ;

[0007] Treating the duration of each hop in frequency hopping as a time slot in a TDMA self-organizing network, that is, the duration t of each frequency point hop Consider it as a time slot in a TDMA self-organizing network, and then take N consecutive time slots as a superframe. According to function, the N time slots contained in a superframe are divided into 1 network management time slot, 1 access time slot, and N-2 service time slots.

[0008] Step 2: The internal structure of each time slot is sequentially divided into the front protection interval, synchronization symbol, reference symbol, data symbol, and rear protection interval;

[0009] Step 3: Nodes not connected to the network perform network time synchronization and access.

[0010] For a node in a network to be connected, the specific process of performing network time synchronization and access is as follows:

[0011] Step 31: The node to be connected to the network is at a random frequency f. w Wait and perform sliding cross-correlation calculation on the baseband data received at this frequency point and the local synchronization sequence until the sliding cross-correlation peak is detected before proceeding to step 32.

[0012] Step 32: The node waiting to connect to the network records the current waiting frequency f. w And the time t for detecting the peak of the sliding cross-correlation. p According to t p obtain frequency point f w The start time t of the corresponding time slot s :

[0013] t s =t p -Δt s,p

[0014] Where, Δt s,p To detect the time and frequency point f of the sliding cross-correlation peak w The time difference between the start times of the corresponding time slots;

[0015] Step 33: Based on the position of the detected sliding cross-correlation peak, determine the positions of the synchronization symbol, reference symbol, and each data symbol in the baseband data received in Step 31. After extracting the reference symbol and each data symbol, perform FFT, channel estimation, channel equalization, constellation demodulation, channel decoding, and CRC check on the extracted data in sequence.

[0016] If the CRC check result is incorrect, the receiving frequency of the node to be connected to the network will be randomly changed to f′. w Then proceed to step 31; if the CRC check result is correct, continue to step 34.

[0017] Step 34: Based on the information in the frame header of the data packet with a correct CRC check result, obtain the time slot where the data packet is located and the specific frequency hopping table used by the current frequency hopping network;

[0018] Based on the frequency point of the data packet with the correct CRC check result recorded in step 32, and in conjunction with the frequency hopping table used by the current frequency hopping network, the node to be connected to the network obtains the subsequent frequency hopping frequency points of the network; and performs frequency hopping in the order of the obtained subsequent frequency hopping frequency points of the network.

[0019] Based on the time t obtained in step 32 s The start time of each superframe is calculated based on the time slot where the data packet is located. The node to be connected to the network performs a preliminary correction between its own time and the time in the network based on the calculated start time of each superframe, that is, aligns its own time with the calculated start time of the superframe.

[0020] Step 35: Based on the calculated start time of each superframe and the position of the access time slot in the superframe, obtain the time corresponding to the access time slot. At the time corresponding to the access time slot, send the access request information using the frequency hopping point corresponding to the access time slot.

[0021] Step 36: After receiving an access request from a node seeking to join the network, a node in the network determines its access method based on Δt. s,p Calculate the start time t of the access time slot where the access request is located. ra and the time information t ra This is fed back to the node in the network to be connected as part of the response to the access request;

[0022] Step 37: After receiving the access request reply, the node to be connected to the network uses the time information t fed back in the access request reply. ra and the time t for receiving the access request response rack Calculate the propagation delay Δt between nodes in the network and nodes in the network to be connected. d With clock deviation Δt a ;

[0023] Based on the calculated Δt a The clock deviation is corrected to complete the connection process;

[0024] Step 4: For nodes already connected to the network, correct clock deviations in real time during communication.

[0025] The beneficial effects of this invention are:

[0026] This invention aligns frequency-hopping time slots with TDMA (Telematics-based DMA) ad hoc network time slots. By completing the time synchronization and tracking correction process of the TDMA ad hoc network, it simultaneously achieves synchronization acquisition and tracking of the frequency-hopping system, making the network access process simpler and faster. Through the synchronization symbols carried within each time slot, the receiver can accurately determine the position of each symbol, complete signal demodulation, and realize information transmission. Furthermore, the design of the front and rear guard intervals effectively addresses the impact of different clock deviations and propagation delays during interconnection between nodes in the ad hoc network. Using the method of this invention, synchronization and access of a broadband frequency-hopping system in a TDMA ad hoc network scenario can be achieved. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the physical layer time slots and frame structure;

[0028] Figure 2 This is a schematic diagram illustrating the time synchronization calculation for nodes to be connected to the network.

[0029] Figure 3 Flowchart for node access;

[0030] Figure 4 A diagram illustrating double the propagation delay for access time slots;

[0031] Figure 5(a) is a schematic diagram of a time-leading node sending data to a time-lagging node, with the propagation delay being less than the clock deviation.

[0032] Figure 5(b) is a schematic diagram of a time-leading node sending data to a time-lagging node, with the propagation delay being greater than the clock deviation.

[0033] Figure 5(c) is a schematic diagram of a time-lagging node sending data to a time-leading node;

[0034] Figure 6 This is a flowchart for node tracking. Detailed Implementation

[0035] Specific Implementation Method 1: Combination Figure 3 This embodiment describes a method for access synchronization and tracking in a TDMA self-organizing network broadband frequency hopping system. The method specifically includes the following steps:

[0036] Step 1: Preset M selectable frequency hopping tables, and each frequency hopping table contains several frequency hopping points (wherein, the number of frequency hopping points in each frequency hopping table can be the same or different), and the duration of each frequency point is t. hop ;

[0037] Treating the duration of each hop in frequency hopping as a time slot in a TDMA self-organizing network, that is, the duration t of each frequency point hop Consider it as a time slot in a TDMA self-organizing network, and then take N consecutive time slots as a superframe. According to function, the N time slots contained in a superframe are divided into 1 network management time slot, 1 access time slot, and N-2 service time slots.

[0038] Step 2: The internal structure of each time slot is sequentially divided into the pre-protection interval, synchronization symbol, reference symbol, data symbol, and post-protection interval, as follows: Figure 1 As shown;

[0039] The front guard interval protects against clock deviations caused by physical factors such as crystal oscillator offsets between communication nodes, while the rear guard interval protects against frequency switching time, transmission delays caused by long-distance transmission, and clock deviations. Synchronization symbols are complex sequences with good cross-correlation characteristics, used to determine the precise position of each symbol within a time slot. Reference symbols are used for channel estimation and equalization, and data symbols are used to carry service data.

[0040] Step 3: Nodes not connected to the network perform network time synchronization and access.

[0041] For a node in a network to be connected, the specific process of performing network time synchronization and access is as follows:

[0042] Step 31: The node to be connected to the network is at a random frequency f. w (At this time, the frequency point remains unchanged, that is, no frequency hopping is performed) and waits, and performs sliding cross-correlation operation on the baseband data received at this frequency point and the local synchronization sequence until the sliding cross-correlation peak is detected before executing step 32.

[0043] Step 32: The node waiting to connect to the network records the current waiting frequency f. w And the time t for detecting the peak of the sliding cross-correlation. p According to t p obtain frequency point f w The start time t of the corresponding time slot s :

[0044] t s =t p -Δt s，p

[0045] Where, Δt s,p To detect the time and frequency point f of the sliding cross-correlation peak w The time difference between the start time of the corresponding time slot; under normal communication conditions, since the position of the synchronization symbol in the time slot is fixed, the time when the peak is detected is the same as the start time t of that time slot. s The time difference Δt between s,p It is fixed;

[0046] Step 33: Based on the position of the detected sliding cross-correlation peak, determine the positions of the synchronization symbol, reference symbol, and each data symbol in the baseband data received in Step 31. After extracting the reference symbol and each data symbol based on the synchronization position, perform FFT, channel estimation, channel equalization, constellation demodulation, channel decoding, and CRC check (cyclic redundancy check) on the extracted data in sequence.

[0047] If the CRC check result is incorrect, the receiving frequency of the node to be connected to the network will be randomly changed to f′. w(that is, f) w Change to f′ w If the CRC check result is correct, proceed to step 34.

[0048] Step 34: Based on the information in the frame header of the data packet with a correct CRC check result, obtain the time slot where the data packet is located and the specific frequency hopping table used by the current frequency hopping network;

[0049] Based on the frequency point of the data packet with the correct CRC check result recorded in step 32, and in conjunction with the frequency hopping table used by the current frequency hopping network, the node to be connected to the network obtains the subsequent frequency hopping points of the network (after obtaining the subsequent frequency hopping points of the network, the node to be connected to the network can know which frequency point the network is communicating on at any subsequent time, and can send information to and receive information from nodes in the network on the correct frequency point); and performs frequency hopping according to the obtained subsequent frequency hopping points of the network;

[0050] Based on the time t obtained in step 32 s The start time of each superframe is calculated based on the time slot where the data packet is located. The node to be connected to the network performs a preliminary correction between its own time and the time in the network based on the calculated start time of each superframe, that is, aligns its own time with the calculated start time of the superframe (time alignment with any superframe is acceptable).

[0051] Step 35: Based on the calculated start time of each superframe and the position of the access time slot in the superframe, obtain the time corresponding to the access time slot. At the time corresponding to the access time slot, send the access request information using the frequency hopping point corresponding to the access time slot.

[0052] Step 36: After receiving an access request from a node seeking to join the network, a node in the network determines its access method based on Δt. s,p Calculate the start time t of the access time slot where the access request is located. ra and the time information t ra This is fed back to the node in the network to be connected as part of the response to the access request;

[0053] Step 37: After receiving the access request reply, the node to be connected to the network uses the time information t fed back in the access request reply. ra and the time t for receiving the access request response rack Calculate the propagation delay Δt between nodes in the network and nodes in the network to be connected. d With clock deviation Δt a ;

[0054] Based on the calculated Δt a The clock deviation is corrected to complete the connection process;

[0055] Step 4: For nodes already connected to the network, due to the differences in the device clocks between nodes, deviations will occur over time, and the clock deviation needs to be corrected in real time during communication.

[0056] Specific Implementation Method Two: This implementation method is a further limitation of Specific Implementation Method One. The network management time slot is used by the cluster head node in the TDMA self-organizing network to broadcast network control information to other slave nodes.

[0057] Specific Implementation Method 3: This implementation method is a further limitation of Specific Implementation Method 2. The access time slot is used for nodes in the network to be accessed to initiate access requests.

[0058] Specific Implementation Method Four: This implementation method is a further limitation of Specific Implementation Method Three. The service time slot is used for data service exchanges between nodes in the TDMA self-organizing network.

[0059] Specific Implementation Method Five: Combining Figure 2 This embodiment describes a further limitation of specific embodiment four, where the time information t fed back in the access request reply is used. ra and the time t for receiving the access request response rack Calculate the propagation delay Δt d With clock deviation Δt a The specific process is as follows:

[0060] Let t be the time when the node to be connected to the network sends the access request. sa The time t is the time it takes for a node in the network to send a response to an access request. sack ,but

[0061]

[0062] Where, Δt a Δt represents the clock skew between nodes in the existing network and nodes in the network to be connected, where the node to be connected lags behind the nodes in the existing network. d This represents the propagation delay between nodes in the network and nodes in the network to be connected.

[0063] Solving for:

[0064]

[0065] Specific Implementation Method Six: This implementation method is a further limitation of Specific Implementation Method Five, wherein the length of the post-protection interval of the access time slot is twice the length of the post-protection interval of other time slots.

[0066] The internal structure of network management time slots and service time slots is sequentially divided into a front protection interval, one synchronization symbol, one reference symbol, L data symbols, and a rear protection interval. For example... Figure 4 As shown, the post-guard interval length of the access time slot is twice that of other time slots. While maintaining the entire time slot length as one hop, the number of data symbols in the access time slot must be less than L. This is because, in this invention, the post-guard interval is used to protect against frequency switching time, transmission delay caused by long-distance transmission, and clock skew. During communication, the frequency switching time is a fixed and relatively small value, while the clock skew gradually increases over time and is corrected after exceeding a preset threshold. Therefore, a larger post-guard interval is used to address transmission delays in long-distance communication. However, during access, due to the unknown propagation delay, the network time initially confirmed by the node to be accessed in step 34 may deviate significantly from the actual time of nodes in the network, approximately equal to the propagation delay. Therefore, the information sent by the node to be accessed will have double the propagation delay in the time difference before reaching the receiving node. Thus, to avoid time slot conflicts, the information length sent in the access time slot should be shorter, and the corresponding post-guard interval should be longer, approximately twice that of other time slots.

[0067] Specific implementation method seven: Combining Figure 6 This embodiment is a further limitation of specific embodiment six. The specific process of step 4 is as follows:

[0068] Step 41: Set any one node in the network as the master node, and then set the remaining nodes as slave nodes, using the time of the master node as the reference.

[0069] Step 42: During the communication process, whenever the slave node receives data from the master node, the signal delay from the master node to the slave node is calculated based on the time of data reception. When the signal delay from the master node to the slave node exceeds the set range [t1, t2], the slave node sends a time correction request.

[0070] Where t1 is the propagation delay between the master node and the slave node during the last clock skew correction, and the preset threshold Δt. m The difference, t2, is the propagation delay between the master node and the slave node during the last clock skew correction, compared to the preset threshold Δt. m The sum of;

[0071] Before the first clock skew correction, the propagation delay between the master node and the slave node during the last clock skew correction is the propagation delay calculated during the node access process.

[0072] Step 43: After receiving the time correction request from the slave node, the master node records the time t when the time correction request was received. rc and the time information trc As part of the response to the time correction request, it is fed back to the slave node that initiated the time correction request;

[0073] Step 44: After receiving the time correction request response from the node, adjust the time t according to the time feedback in the time correction request response. rc and the time t′ when the time correction request response is received rack Calculate the current propagation delay and clock skew between the master node and the slave node;

[0074] The node performs clock offset correction based on the calculated current clock offset, thus completing the time correction process.

[0075] Specific Implementation Method Eight: This implementation method is a further limitation of Specific Implementation Method Seven, wherein the threshold Δt m Not greater than min{t sp ,t ep -Δt d,max}, where t sp t is the length of the front protection interval. ep The length of the post-protection interval (the length of the post-protection interval for network management time slots or service time slots), Δt d,max This represents the maximum transmission delay.

[0076] The front guard interval is set to address the accumulated clock skew during communication. When a clock skew exists between two nodes, their times will inevitably exhibit a lag and a lead relationship. When the clock skew between two nodes is Δt... m ≥0, propagation delay is 0≤Δt d ≤Δt d,max , where Δt d,max Let t be the maximum transmission delay in the application scenario. As shown in Figures 5(a) and 5(b), the combined delay for a node sending information that is relatively ahead in time to a node that is relatively behind in time is Δt. d -Δt m As shown in Figure 5(c), the combined delay of information sent by a relatively lagging node to a relatively leading node is Δt. d +Δt m .

[0077] The current protection interval length is t sp The length of the rear protection interval is t ep In order to ensure that the information transmitted between the two nodes can be received correctly, the following conditions must be met.

[0078]

[0079] We can obtain:

[0080] Δtm ≤min{t sp ,t ep -Δt d,max}

[0081] That is, the preset clock deviation threshold should not be greater than min{t} sp ,t ep -Δt d,max}

[0082] Specific Implementation Method Nine: This implementation method is a further limitation of Specific Implementation Method Eight, wherein the time t fed back in the time correction request reply is... rc and the time t′ when the time correction request response is received rack The current propagation delay and clock offset between the master node and the slave node are calculated; the specific process is as follows:

[0083] Let t′ be the time when the slave node sends the time correction request. sa The time it takes for the master node to reply to the time correction request is t′. sack ,but

[0084]

[0085] Where, Δt′ a Δt′ represents the current clock skew between the master and slave nodes. d This represents the current propagation delay between the master node and the slave node;

[0086] Solving for:

[0087]

[0088] The calculation process in this embodiment is the same as step 37.

[0089] The above examples of the present invention are merely illustrative of the computational model and process of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for access synchronization and tracking in a TDMA self-organizing network broadband frequency hopping system, characterized in that, The method specifically includes the following steps: Step 1: Pre-set M frequency hopping tables, and each frequency hopping table contains several frequency points, the duration of each frequency point is t. hop ; Treating the duration of each hop in frequency hopping as a time slot in a TDMA self-organizing network, that is, the duration t of each frequency point hop Consider it as a time slot in a TDMA self-organizing network, and then take N consecutive time slots as a superframe. According to function, the N time slots contained in a superframe are divided into 1 network management time slot, 1 access time slot, and N-2 service time slots. Step 2: The internal structure of each time slot is sequentially divided into the front protection interval, synchronization symbol, reference symbol, data symbol, and rear protection interval; Step 3: Nodes not connected to the network perform network time synchronization and access. For a node in a network to be connected, the specific process of performing network time synchronization and access is as follows: Step 31: The node to be connected to the network is at a random frequency f. w Wait, and perform sliding cross-correlation calculation on the baseband data received at this frequency point and the local synchronization sequence until the sliding cross-correlation peak is detected before proceeding to step 32; Step 32: The node waiting to connect to the network records the current waiting frequency f. w And the time t for detecting the peak of the sliding cross-correlation. p According to t p obtain frequency point f w The start time t of the corresponding time slot s : t s =t p -Δt s，p Where, Δt s,p To detect the time and frequency point f of the sliding cross-correlation peak w The time difference between the start times of the corresponding time slots; Step 33: Based on the position of the detected sliding cross-correlation peak, determine the positions of the synchronization symbol, reference symbol, and each data symbol in the baseband data received in Step 31. After extracting the reference symbol and each data symbol, perform FFT, channel estimation, channel equalization, constellation demodulation, channel decoding, and CRC check on the extracted data in sequence. If the CRC check result is incorrect, the receiving frequency of the node to be connected to the network will be randomly changed to f′. w Then proceed to step 31; if the CRC check result is correct, continue to step 34. Step 34: Based on the information in the frame header of the data packet with a correct CRC check result, obtain the time slot where the data packet is located and the specific frequency hopping table used by the current frequency hopping network; Based on the frequency point of the data packet with the correct CRC check result recorded in step 32, and in conjunction with the frequency hopping table used by the current frequency hopping network, the node to be connected to the network obtains the subsequent frequency hopping frequency points of the network; and performs frequency hopping in the order of the obtained subsequent frequency hopping frequency points of the network. Based on the time t obtained in step 32 s The start time of each superframe is calculated based on the time slot in which the data packet is located. The node to be connected to the network performs a preliminary correction between its own time and the time in the network based on the calculated start time of each superframe, that is, aligns its own time with the calculated start time of the superframe. Step 35: Based on the calculated start time of each superframe and the position of the access time slot in the superframe, obtain the time corresponding to the access time slot. At the time corresponding to the access time slot, send the access request information using the frequency hopping point corresponding to the access time slot. Step 36: After receiving an access request from a node seeking to join the network, a node in the network determines its access method based on Δt. s,p Calculate the start time t of the access time slot where the access request is located. ra and the time information t ra This is fed back to the node in the network to be connected as part of the response to the access request; Step 37: After receiving the access request reply, the node to be connected to the network uses the time information t fed back in the access request reply. ra and the time t for receiving the access request response rack Calculate the propagation delay Δt between nodes in the network and nodes in the network to be connected. d With clock deviation Δt a ; Based on the calculated Δt a The clock deviation is corrected to complete the connection process; Step 4: For nodes already connected to the network, correct clock deviations in real time during communication.

2. The access synchronization and tracking method for a TDMA self-organizing network broadband frequency hopping system according to claim 1, characterized in that, The network management time slot is used by the cluster head node in the TDMA self-organizing network to broadcast network control information to other slave nodes.

3. The TDMA self-organizing network broadband frequency hopping system access synchronization and tracking method according to claim 2, characterized in that, The access time slot is used for nodes in the network to initiate access requests.

4. The access synchronization and tracking method for a TDMA self-organizing network broadband frequency hopping system according to claim 3, characterized in that, The service time slots are used for data service exchanges between nodes in a TDMA self-organizing network.

5. The TDMA self-organizing network broadband frequency hopping system access synchronization and tracking method according to claim 4, characterized in that, The time information t fed back in the access request reply is used as a basis. ra and the time t for receiving the access request response rack Calculate the propagation delay Δt d With clock deviation Δt a The specific process is as follows: Let t be the time when the node to be connected to the network sends the access request. sa The time t is the time it takes for a node in the network to send a response to an access request. sack ,but Where, Δt a Δt represents the clock skew between nodes in the existing network and nodes in the network to be connected. d This represents the propagation delay between nodes in the network and nodes in the network to be connected. Solving for:

6. The access synchronization and tracking method for a TDMA self-organizing network broadband frequency hopping system according to claim 5, characterized in that, The length of the post-protection interval of the access time slot is twice the length of the post-protection interval of other time slots.

7. The TDMA self-organizing network broadband frequency hopping system access synchronization and tracking method according to claim 6, characterized in that, The specific process of step 4 is as follows: Step 41: Set any one node in the network as the master node, and then set the remaining nodes as slave nodes, using the time of the master node as the reference. Step 42: During the communication process, whenever the slave node receives data from the master node, the signal delay from the master node to the slave node is calculated based on the time of data reception. When the signal delay from the master node to the slave node exceeds the set range [t1, t2], the slave node sends a time correction request. Where t1 is the propagation delay between the master node and the slave node during the last clock skew correction, and the preset threshold Δt. m The difference, t2, is the propagation delay between the master node and the slave node during the last clock skew correction, compared to the preset threshold Δt. m The sum of; Step 43: After receiving the time correction request from the slave node, the master node records the time t when the time correction request was received. rc and the time information t rc This is fed back to the slave node that initiated the time correction request as part of the response to the time correction request; Step 44: After receiving the time correction request response from the node, adjust the time t according to the time feedback in the time correction request response. rc And the time t when the time correction request reply is received r ′ ack Calculate the current propagation delay and clock skew between the master node and the slave node; The node performs clock offset correction based on the calculated current clock offset, thus completing the time correction process.

8. The access synchronization and tracking method for a TDMA self-organizing network broadband frequency hopping system according to claim 7, characterized in that, The threshold Δt m Not greater than min{t sp ,t ep -Δt d,max }, where t sp t is the length of the front protection interval. ep Δt is the length of the rear protection interval. d,max This represents the maximum transmission delay.

9. The access synchronization and tracking method for a TDMA self-organizing network broadband frequency hopping system according to claim 8, characterized in that, The time t fed back in the time correction request reply rc and the time t′ when the time correction request response is received rack The current propagation delay and clock offset between the master node and the slave node are calculated; the specific process is as follows: Let t′ be the time when the slave node sends the time correction request. sa The time it takes for the master node to reply to the time correction request is t′. sack ,but Where, Δt′ a Δt′ represents the current clock skew between the master and slave nodes. d This represents the current propagation delay between the master node and the slave node; Solving for:

Images