CN115580319B - GNSS-assisted trunking cooperative differential frequency hopping communication system and method - Google Patents
GNSS-assisted trunking cooperative differential frequency hopping communication system and method Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7136—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7136—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform
- H04B2001/71365—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform using continuous tuning of a single frequency source
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
- H04B2001/7152—Interference-related aspects with means for suppressing interference
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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Abstract
The invention discloses a GNSS assisted trunking cooperative differential frequency hopping communication system and a GNSS assisted trunking cooperative differential frequency hopping communication method. The system consists of a central control unit and user nodes. Each node is configured with a GNSS receiver that provides accurate position information and time information for each node. In a cluster cooperative network of differential frequency hopping communication, a central control unit distributes a series of space-time variable G function clusters for each node according to position information reported by each node and current frequency hopping, and the G function clusters can be dynamically adjusted according to the number of nodes in a real-time access network and a set updating time period. The system has the advantages that at the same time, the frequency of the frequency hopping multiple users is different, so that the crosstalk between users can be effectively prevented; the position information provided by the GNSS receiver can ensure that the frequency hopping intervals of users with adjacent positions are larger, and can effectively reduce multiple access interference. The invention can improve the differential frequency hopping communication efficiency and the anti-interference performance of the cluster cooperative system under the assistance of GNSS.
Description
Technical Field
The invention belongs to the field of frequency hopping communication systems, and particularly relates to a cluster cooperative differential frequency hopping communication system and method assisted by a global navigation satellite system (Global Navigation Satellite System, GNSS).
Background
With the increasing complexity of electromagnetic environment and the increasing sophistication of electronic information, communication systems often suffer from multi-user crosstalk signals while completing voice, data and other services. The communication system should adopt an effective communication mode to enhance the reliability of information transmission, thereby improving the anti-interference capability of the system.
Conventional frequency hopping communications employ a Pseudo-random sequence (PN) to control carrier frequency variation to achieve Pseudo-random hopping of frequencies. Differential frequency hopping is a novel spread spectrum communication technology and is completely different from the conventional frequency hopping technology system. The difference is that: the traditional frequency hopping working frequency point is controlled by a pseudo-random sequence, and the frequency hopping sequence of the differential frequency hopping is determined by the last frequency hopping working frequency point and the current frequency hopping information together; the information transmitted by differential frequency hopping is hidden in the relative positions of the front frequency point and the rear frequency point, and the carrier wave is not modulated; the differential frequency hopping transmitter directly synthesizes the transmission frequency by using the DDS. Based on the above differences, differential frequency hopping communication has the following advantages: the information is transmitted by utilizing the correlation between the front frequency point and the rear frequency point, so that the potential error correction capability is realized; the residence time of each hop of frequency is extremely short, the high-speed data transmission capability is provided, and the tracking interference resistance of the system is strong; theoretically, the period of the frequency hopping pattern is infinitely long, so that the frequency hopping pattern is not easy to crack and has good confidentiality; the receiving end demodulates the information through the correlation of the front frequency hopping point and the back frequency hopping point, does not need to track the frequency hopping of the transmitting end, and belongs to asynchronous frequency hopping without accurate timing.
The design of the differential frequency hopping pattern determines the performance of the differential frequency hopping communication system and the strength of the anti-interference capability. The design of the differential hopping pattern is determined by the frequency transfer function, the G-function. At the receiving end, the data information of the transmitting end can be recovered through the inverse transformation of the G function. The differential frequency hopping system receiver adopts a broadband receiving technology to perform symbol-by-symbol detection on a received signal or perform sequence detection by utilizing the correlation among frequency hopping frequency points. The design method of the G function mainly comprises a G function method based on a linear congruence theory, a G function method based on a fuzzy and chaos theory, a G function construction method based on a cryptography algorithm and the like. The design of the frequency transfer function described above is based primarily on a single G-function of some theory or algorithm. However, in the differential frequency hopping multi-user networking communication, when the source node transmits data to the target node, if the source node adopts a single G function to generate a frequency hopping frequency point set, the fixed frequency transfer relationship is easily intercepted by a third party along with the increase of the number of receiving frames, so that the anti-interference performance of the target node is reduced. In addition, in the differential frequency hopping multi-user communication, as the receiving end adopts full frequency receiving, multi-user sending data simultaneously appear in the channel, and each user modulates the data by adopting the same G function, the problem of multiple access interference can be brought. Therefore, from the point of view of information interception and multiple access interference, it is difficult to meet the requirements of the system on interception resistance and interference resistance by using a single G function in the differential frequency hopping communication networking system. At present, the cluster cooperative frequency hopping communication technology is used in the fields of unmanned aerial vehicles, intelligent robots, mobile communication stations and the like, but because a single G function is used, crosstalk is easy to generate among all communication users, and the communication quality and efficiency are low.
Disclosure of Invention
Aiming at the problems, the invention provides a GNSS assisted trunking cooperative differential frequency hopping communication system and a method, and the main idea of the invention is as follows: the G function of the differential frequency hopping communication system is designed with assistance from position, velocity, time (PVT) information provided by the GNSS receiver. A central control unit in the system can assign a series of space-time variable G-function clusters to each user. The time information provided by the GNSS receiver enables the frequency of frequency hopping multiple users at the same moment to be different, so that crosstalk among users can be effectively prevented; the position information provided by the GNSS receiver can ensure that the frequency hopping intervals of users with adjacent positions are larger, and can effectively reduce multiple access interference.
The invention adopts the following technical scheme:
according to one aspect of the present invention, there is provided a GNSS assisted trunked cooperative differential hopping communication system comprising:
the central control unit is respectively in communication connection with the N nodes, and the nodes are in communication connection;
each node comprises a GNSS receiver, a transmitting unit and a receiving unit;
the nodes and the central control unit transmit and receive information by adopting a differential frequency hopping communication mode;
each node provides the position information and the current frequency hopping frequency of the node to a central control unit through a GNSS receiver;
the central control unit distributes corresponding frequency transfer function G to each node n ；
The transmitting unit of each node uses the received G n The function is used for processing the input data and the frequency of the last hop, generating a differential frequency hopping signal of the current hop and transmitting the differential frequency hopping signal through an antenna;
the receiving unit of each node receives the differential frequency hopping signal through the antenna, detects and decodes the differential frequency hopping signal, and simultaneously demodulates the center in the data information obtained by decodingFrequency transfer function G assigned to the node by the control unit n And apply the G n The function is updated to the G function at the current time of the node.
Preferably, the central control unit comprises: the frequency set distributor is connected with the N G function generators;
the frequency set distributor is used for transmitting the current hop frequency set { f according to the node 1 ,,f 2 ,…,f N Sum of current position information set { P } 1 ,P 2 ,…,P N Dividing the differential hopping frequency set M into N different frequency subsets;
the frequency set distributor is further configured to send N different frequency subsets to corresponding N G function generators, respectively;
the frequency set distributor is further used for randomly distributing G functions of different types to the N G function generators;
n G function generators for distributing corresponding frequency transfer function G to each node n 。
Preferably, the transmitting unit includes: buffer, G n The system comprises a function module, a frequency synthesizer, a first radio frequency module and a transmitting antenna;
the buffer is respectively connected with the G n A function module is connected with the GNSS receiver, and the G is connected with the GNSS receiver n The function module is respectively connected with the GNSS receiver and the frequency synthesizer, the frequency synthesizer is connected with the first radio frequency module, and the first radio frequency module is connected with the transmitting antenna;
the buffer is used for carrying out data frame reorganization on the input data and the position information output by the GNSS receiver, adding the position information into the frame head part of the data frame, and transmitting the data in a framing mode;
the G is n A function module for receiving time information sent by the GNSS receiver in the node, thereby controlling the accurate time of generating the frequency hopping sequence, G n The function module jointly determines the frequency of the current jump according to the frequency of the previous jump and the information symbol to be loaded in the current jump;
the frequency synthesizer is used for generating a differential frequency hopping frequency point according to the current frequency hopping frequency and transmitting the differential frequency hopping frequency point to the first radio frequency module;
the first radio frequency module is used for converting the differential frequency hopping frequency point into a differential frequency hopping signal through the transmitting antenna and transmitting the differential frequency hopping signal to a receiving unit of another node in the network;
the receiving unit includes: the device comprises a receiving antenna, a second radio frequency module, an FFT module, a signal detection module and a frequency sequence decoder;
the receiving antenna is connected with the second radio frequency module, the second radio frequency module is connected with the FFT module, the FFT module is connected with the signal detection module, and the signal detection module is respectively connected with the GNSS receiver and the frequency sequence decoder;
the receiving antenna is used for transmitting the received signals to the second radio frequency module;
the radio frequency module is used for down-converting the signals into intermediate frequency signals, sampling the intermediate frequency signals through an intermediate frequency filter AD in the radio frequency module and then transmitting the signals to the FFT module;
the FFT module is used for performing fast Fourier transform on the frequency hopping signal;
the signal detection module is used for receiving the time information sent by the GNSS receiver and detecting signals by adopting a sequence detection method;
the frequency sequence decoder is used for performing frequency sequence decoding on the detected differential frequency hopping sequence, and finally taking the decoded data information as output, and simultaneously demodulating the frequency transfer function G distributed to the node by the central control unit in the decoded data information n And apply the G n The function is updated to the frequency transfer function at the current time of the node.
According to another aspect of the present invention, the present invention provides a method for GNSS assisted trunking cooperative differential frequency hopping communication, implemented based on the GNSS assisted trunking cooperative differential frequency hopping communication system, including the steps of:
s1: at the time of the update of the time,the central control unit generates space-time differential frequency hopping G function clusters { G }, according to the current frequency hopping frequency and the position information of each node 1 ,G 2 ,…,G n ,…,G N And will correspond to G n The function is distributed to the corresponding node n;
s2: the transmitting unit of each node uses the received G n The function is used for processing the input data and the frequency of the last hop, generating a differential frequency hopping signal of the current hop and transmitting the differential frequency hopping signal through a transmitting antenna;
s3: the receiving unit of each node receives the differential frequency hopping signal through the receiving antenna, detects and decodes the differential frequency hopping signal, and simultaneously demodulates the frequency transfer function G distributed to the node by the central control unit in the data information obtained by decoding n And apply the G n The function is updated to the G function at the current time of the node.
Preferably, step S1 specifically includes:
s1.1: let T be the updated time interval, at the moment of integer multiple of T, each node will hop the current frequency f n And current position information P n A frequency set allocator sent to the central control unit;
s1.2: the frequency set distributor divides the differential frequency hopping frequency set M into N different frequency subsets according to the current frequency hopping frequency set and the current position information set which are sent by the node;
s1.3: the frequency set distributor respectively transmits N different frequency subsets to the corresponding N function generators;
s1.4: the frequency set distributor randomly distributes a G function of different types for the N function generators;
s1.5: the central control unit distributes corresponding G functions for each node respectively, and the central control unit outputs a series of space-time variable G function clusters;
s1.6: and updating the current hopping frequency and the current position information once by each node according to a fixed time interval T, reporting the current hopping frequency and the current position information to the central control unit again, and then sequentially repeating the steps S1.1 to S1.5, and dynamically updating to generate a series of new space-time variable G function clusters.
Preferably, step S1.2 specifically includes:
s1.2.1: the frequency set distributor draws space-time occupation grid diagrams of all nodes according to the position information set and the time information set reported by the nodes;
s1.2.2: calculating the distance P between every two nodes i,j The distance between any two nodes is normalized and calculated by the maximum value of the distance between every two nodes;
s1.2.3: dividing frequency subsets according to the principle that the closer the distance between two nodes is, the larger the frequency interval is;
s1.2.4: frequency set allocator reports frequency hopping frequency set { f } to node 1 ,,f 2 ,…,f N Monitor.
Optionally, in step S1.4, the different types of G functions include: any one of a G function based on a linear congruence theory, a G function based on chaotic mapping, a G function based on an encryption algorithm and a G function of time-frequency disturbance.
Preferably, in step S1.6, when the number of nodes changes, the central control unit can re-divide different frequency subsets and change G according to the increase or decrease of the position information reported by the nodes n The number of functions.
Preferably, the step S2 specifically includes:
s2.1: the buffer carries out data frame reorganization on the input information data and the position information output by the GNSS receiver, adds the position information into the frame head part of the data frame, and transmits the data in a framing mode;
s2.2: the GNSS receiver in the node inputs time information into the function of the node to control the accurate time generated by the frequency hopping sequence, and the function jointly determines the frequency of the current hop by the frequency of the last hop and the information symbol needed to be loaded by the current hop;
s2.3: the frequency synthesizer generates a differential frequency hopping frequency point according to the current frequency hopping frequency and sends the differential frequency hopping frequency point to the first radio frequency module;
s2.4: the first radio frequency module converts the differential frequency hopping frequency point into a differential frequency hopping signal through a transmitting antenna and sends the differential frequency hopping signal to a receiving unit of another node in the network.
Preferably, the step S3 specifically includes:
s3.1: the receiving antenna transmits the received signal to the second radio frequency module;
s3.2: the second radio frequency module down-converts the signal into an intermediate frequency signal, and the intermediate frequency signal is sampled by an intermediate frequency filter AD in the second radio frequency module and then transmitted to the FFT module;
s3.3: the FFT module performs fast Fourier transform on the intermediate frequency signal;
s3.4: the GNSS receiver inputs the time information to a signal detection module, and the signal detection module detects the FFT-transformed signals by adopting a sequence detection method;
s3.5: the frequency sequence decoder decodes the frequency sequence of the differential frequency hopping sequence obtained by detection, finally takes the decoded data information as output, and simultaneously demodulates the frequency transfer function G distributed to the node by the central control unit in the decoded data information n And apply the G n The function is updated to the G function at the current time of the node.
The technical scheme provided by the invention has the beneficial effects that:
(1) The central control unit uniformly designs G function frequency hopping clusters for the cluster cooperative differential frequency hopping communication system, distributes independent G functions for different user nodes, and each node performs frequency sequence decoding by using the distributed G functions, so that multiple access interference caused by the fact that the cluster cooperative nodes all use a single G function can be effectively avoided;
(2) The novel space-time variable G function clusters generated by the central control unit can reduce the probability that a fixed frequency transfer relation determined by a single G function is intercepted by a third party, so that the anti-interference capability of the cooperative nodes of the cluster is effectively improved;
(3) Accurate time information provided by a GNSS receiver is utilized to facilitate accurate modulation and demodulation of differential frequency hopping sequences of all nodes, and an accurate space-time variable G function cluster is obtained;
(4) The frequency points occupied by different nodes at the same time are different, so that crosstalk among multiple nodes can be prevented;
(5) The closer the distance between the nodes is, the larger the frequency phase difference is, so that multiple access interference caused by the similar frequency between the nodes can be prevented;
(6) The G function of each node has time variability, so that the confidentiality and the interception resistance of the system are improved.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a block diagram of a GNSS assisted trunked cooperative differential hopping communications system in accordance with an embodiment of the present invention;
FIG. 2 is a block diagram of a central control unit for generating space-time variable G-function clusters in an embodiment of the present invention;
FIG. 3 is a block diagram of a GNSS assisted node transceiver unit in accordance with an embodiment of the present invention.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.
Embodiment one:
referring to fig. 1, fig. 1 is a block diagram of a GNSS assisted trunked cooperative differential hopping communication system according to the present invention. The GNSS assisted trunking cooperative frequency hopping communication system of the invention comprises: a central control unit and nodes (node 1, node 2, … …, node N); each node comprises a GNSS receiver, and the GNSS receiver refers to a module, a chip or a physical machine which can finish a GNSS positioning function and provide PVT information; each node comprises a transmitting unit and a receiving unit; the nodes and the central control unit transmit and receive information by adopting a differential frequency hopping communication mode; each node provides the position information and the current frequency hopping frequency of the node to a central control unit through a GNSS receiver; the central control unit distributes corresponding frequency transfer functions to each node; the transmitting unit of each node processes the input data and the frequency of the last hop by using the received function, generates a differential frequency hopping signal of the current hop, and transmits the differential frequency hopping signal through an antenna; the receiving unit of each node receives the differential frequency hopping signal through the antenna, detects and decodes the differential frequency hopping signal, simultaneously demodulates the frequency transfer function distributed to the node by the central control unit in the data information obtained by decoding, and updates the function into the G function of the current moment of the node.
The invention is suitable for the cluster collaborative differential frequency hopping communication system of unmanned aerial vehicles, intelligent robots, mobile communication stations and the like, can allocate different nodes for users in the cluster, and selects one of the users as a central control unit. The central control unit can respectively allocate different frequency transfer functions for each user according to the position information and the current frequency hopping information reported by other users.
Referring to fig. 2, fig. 2 is a block diagram of a central control unit for generating space-time variable G-function clusters according to the present invention. The central control unit includes: frequency set divider and N G function generators (G 1 Function generator, G 2 Function generators, … …, G N A function generator); frequency set distributor and G respectively 1 Function generator, G 2 Function generator, … …, G N The function generator is connected.
A frequency set distributor for distributing the current hop frequency set { f } sent by the node 1 ,,f 2 ,…,f N Sum of current position information set { P } 1 ,P 2 ,…,P N Dividing the differential hopping frequency set M into N different frequency subsets;
the frequency set distributor is further used for respectively transmitting the N different frequency subsets to the N corresponding G function generators;
the frequency set distributor is also used for randomly distributing G functions of different types for the N G function generators;
n G function generators for distributing corresponding frequency transfer function G to each node n 。
Referring to fig. 3, fig. 3 is a block diagram of a GNSS assisted node transceiver unit according to the present invention. The transmitting unit in the node transceiving unit comprises: buffer, G n The system comprises a function module, a frequency synthesizer, a first radio frequency module and a transmitting antenna;
buffers are respectively connected with G n The function module is connected with the GNSS receiver, G n Function moduleThe GNSS receiver is connected with the frequency synthesizer respectively, the frequency synthesizer is connected with the first radio frequency module, and the first radio frequency module is connected with the transmitting antenna;
the buffer is used for carrying out data frame recombination on the input data and the position information output by the GNSS receiver, adding the position information into the frame head part of the data frame and transmitting the data in a framing mode;
G n a function module for receiving time information sent by the GNSS receiver in the node, thereby controlling the accurate time of generating the frequency hopping sequence, G n The function module jointly determines the frequency of the current jump according to the frequency of the previous jump and the information symbol to be loaded in the current jump;
the frequency synthesizer is used for generating a differential frequency hopping frequency point according to the current frequency hopping frequency and transmitting the differential frequency hopping frequency point to the first radio frequency module;
the first radio frequency module is used for converting the differential frequency hopping frequency point into a differential frequency hopping signal through the transmitting antenna and transmitting the differential frequency hopping signal to a receiving unit of another node in the network;
the receiving unit in the node transceiving unit comprises: the device comprises a receiving antenna, a second radio frequency module, an FFT module, a signal detection module and a frequency sequence decoder;
the receiving antenna is connected with the second radio frequency module, the second radio frequency module is connected with the FFT module, the FFT module is connected with the signal detection module, and the signal detection module is respectively connected with the GNSS receiver and the frequency sequence decoder;
the receiving antenna is used for transmitting the received signals to the second radio frequency module;
the radio frequency module is used for down-converting the signals into intermediate frequency signals, sampling the intermediate frequency signals through an intermediate frequency filter AD in the radio frequency module and then transmitting the signals to the FFT module;
the FFT module is used for performing fast Fourier transform on the frequency hopping signal;
the signal detection module is used for receiving the time information sent by the GNSS receiver and detecting the signals by adopting a sequence detection method;
a frequency sequence decoder for performing frequency on the detected differential frequency hopping sequenceSequence decoding, finally taking the decoded data information as output, and simultaneously demodulating the frequency transfer function G distributed to the node by the central control unit in the decoded data information n And apply the G n The function is updated to the G function (frequency transfer function) at the current time of the node.
Embodiment two:
referring to fig. 1, the present embodiment provides a method for GNSS assisted trunking cooperative differential frequency hopping communication, which is implemented based on the GNSS assisted trunking cooperative differential frequency hopping communication system according to the first embodiment, and includes the following steps:
s1: at the update time, the central control unit generates a space-time differential frequency hopping G function cluster { G }, according to the current frequency hopping frequency and the position information of each node 1 ,G 2 ,…,G n ,…,G N And will correspond to G n The function is distributed to the corresponding node n;
s2: the transmitting unit of each node uses the received G n The function is used for processing the input data and the frequency of the last hop, generating a differential frequency hopping signal of the current hop and transmitting the differential frequency hopping signal through a transmitting antenna;
s3: the receiving unit of each node receives the differential frequency hopping signal through the receiving antenna, detects and decodes the differential frequency hopping signal, and simultaneously demodulates the frequency transfer function G distributed to the node by the central control unit in the data information obtained by decoding n And apply the G n The function is updated to the G function at the current time of the node.
As a preferred embodiment, referring to fig. 3, step S1 specifically includes:
s1.1: at times of integer multiple of T (T is the updated time interval), each node will hop the current frequency f n And current position information P n A frequency set allocator sent to the central control unit;
s1.2: the frequency set distributor divides the differential frequency hopping frequency set M into N different frequency subsets according to the current frequency hopping frequency set and the current position information set which are sent by the node;
s1.3: the frequency set distributor respectively transmits N different frequency subsets to the corresponding N function generators;
s1.4: the frequency set distributor randomly distributes a different type of G function for the N function generators;
s1.5: the central control unit distributes corresponding G functions for each node respectively, and the central control unit outputs a series of space-time variable G function clusters;
s1.6: and updating the current hopping frequency and the current position information once by each node according to a fixed time interval T, reporting the current hopping frequency and the current position information to the central control unit again, and then sequentially repeating the steps S1.1 to S1.5, and dynamically updating to generate a series of new space-time variable G function clusters.
Further, the step S1.2 specifically includes:
s1.2.1: the frequency set distributor draws a space-time occupation grid graph of each node according to the position information set and the time information set reported by the node;
s1.2.2: calculating the distance P between every two nodes i,j The distance between any two nodes is normalized and calculated by the maximum value of the distance between every two nodes;
s1.2.3: dividing frequency subsets according to the principle that the closer the distance between two nodes is, the larger the frequency interval is;
s1.2.4: frequency set allocator reports frequency hopping frequency set { f } to node 1 ,,f 2 ,…,f N Monitor.
As an alternative embodiment, in step S1.4, the different types of G functions include: any one of a G function based on a linear congruence theory, a G function based on chaotic mapping, a G function based on an encryption algorithm and a G function of time-frequency disturbance.
Further, in step S1.6, when the number of nodes changes, the central control unit can re-divide different frequency subsets and change G according to the increase or decrease of the position information reported by the nodes n The number of functions.
As a preferred embodiment, referring to fig. 3, at the transmitting end, step S2 specifically includes:
s2.1: the buffer carries out data frame reorganization on the input information data and the position information output by the GNSS receiver, adds the position information into the frame head part of the data frame, and adopts a framing mode to transmit the data;
s2.2: the GNSS receiver in the node inputs time information into the function of the node to control the accurate time generated by the frequency hopping sequence, and the function jointly determines the frequency of the current hop by the frequency of the last hop and the information symbol needed to be loaded by the current hop;
s2.3: the frequency synthesizer generates a differential frequency hopping frequency point according to the current frequency hopping and sends the differential frequency hopping frequency point to the first radio frequency module;
s2.4: the first radio frequency module converts the differential frequency hopping frequency point into a differential frequency hopping signal through a transmitting antenna and sends the differential frequency hopping signal to a receiving unit of another node in the network.
As a preferred embodiment, referring to fig. 3, at the receiving end, step S3 specifically includes:
s3.1: the receiving antenna transmits the received signal to the second radio frequency module;
s3.2: the second radio frequency module down-converts the signal into an intermediate frequency signal, and the signal is transmitted to the FFT module after AD sampling by an intermediate frequency filter in the second radio frequency module;
s3.3: the FFT module performs fast Fourier transform on the intermediate frequency signal;
s3.4: the GNSS receiver inputs the time information into a signal detection module, the signal detection module detects the FFT-transformed signal by adopting a sequence detection method, and the sequence detection method can adopt a sequence length L hops (L is arbitrarily set) as a decision period;
s3.5: the frequency sequence decoder performs frequency sequence decoding on the differential frequency hopping sequence obtained by detection, a possible frequency transfer path is found out through the frequency sequence decoder, incoherent detection is combined, and common combination modes such as linear combination, product combination and the like can be adopted as the combination mode. The linear combination is that the detection values are added and combined, and sent to a decision device to be used as decision variables for decision. Finally, the data information of the transmitting end obtained after decoding is used as output, and the frequency transfer function G distributed to the node by the central control unit can be demodulated while the data information obtained after decoding is obtained n And apply the G n Function updateIs the frequency transfer function (G-function) of the current moment of the node. And finally, storing the frequency transfer function into a function of a transmitting unit.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the terms first, second, third, etc. do not denote any order, but rather the terms first, second, third, etc. are used to interpret the terms as labels.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.
Claims (10)
1. A GNSS assisted trunked cooperative differential hopping communication system comprising:
the central control unit is respectively in communication connection with the N nodes, and the nodes are in communication connection;
each node comprises a GNSS receiver, a transmitting unit and a receiving unit;
the transmitting unit includes: buffer, G n The system comprises a function module, a frequency synthesizer, a first radio frequency module and a transmitting antenna;
the buffer is respectively connected with the G n A function module is connected with the GNSS receiver, and the G is connected with the GNSS receiver n The function module is respectively connected with the GNSS receiver and the frequency synthesizer, the frequency synthesizer is connected with the first radio frequency module, and the first radio frequency module is connected with the transmitting antenna;
the buffer is used for carrying out data frame reorganization on the input data and the position information output by the GNSS receiver, adding the position information into the frame head part of the data frame, and transmitting the data in a framing mode;
the G is n A function module for receiving time information sent by the GNSS receiver in the node, thereby controlling the accurate time of generating the frequency hopping sequence, G n The function module jointly determines the frequency of the current jump according to the frequency of the previous jump and the information symbol to be loaded in the current jump;
the frequency synthesizer is used for generating a differential frequency hopping frequency point according to the current frequency hopping frequency and transmitting the differential frequency hopping frequency point to the first radio frequency module;
the first radio frequency module is used for converting the differential frequency hopping frequency point into a differential frequency hopping signal through the transmitting antenna and transmitting the differential frequency hopping signal to a receiving unit of another node in the network;
the nodes and the central control unit transmit and receive information by adopting a differential frequency hopping communication mode;
each node provides the position information and the current frequency hopping frequency of the node to a central control unit through a GNSS receiver;
the central control unit assigns a corresponding frequency transfer function G to each node n n A function, where G n The function is a G function corresponding to node N, and n=1, 2,..n;
the transmitting unit of each node uses the received G n The function is used for processing the input data and the frequency of the last hop, generating a differential frequency hopping signal of the current hop and transmitting the differential frequency hopping signal through an antenna;
the receiving unit of each node receives the differential frequency hopping signal through the antenna, detects and decodes the differential frequency hopping signal, and simultaneously demodulates the frequency transfer function G distributed to the node by the central control unit in the data information obtained by decoding n And apply the G n The function is updated to the G function at the current time of the node.
2. The GNSS assisted trunked cooperative differential hopping communication system of claim 1, wherein the central control unit comprises: the frequency set distributor is connected with the N G function generators;
the frequency set distributor is used for transmitting the current frequency hopping frequency set { f according to the node 1 ,f 2 ,…,f N Sum of current position information set { P } 1 ,P 2 ,…,P N Dividing the differential hopping frequency set M into N different frequency subsets;
the frequency set distributor is further configured to send N different frequency subsets to corresponding N G function generators, respectively;
the frequency set distributor is further used for randomly distributing G functions of different types to the N G function generators;
n G function generators for distributing corresponding frequency transfer function G to each node n 。
3. The GNSS assisted trunked cooperative differential frequency hopping communication system of claim 2,
the receiving unit includes: the device comprises a receiving antenna, a second radio frequency module, an FFT module, a signal detection module and a frequency sequence decoder;
the receiving antenna is connected with the second radio frequency module, the second radio frequency module is connected with the FFT module, the FFT module is connected with the signal detection module, and the signal detection module is respectively connected with the GNSS receiver and the frequency sequence decoder;
the receiving antenna is used for transmitting the received signals to the second radio frequency module;
the second radio frequency module is used for down-converting the signals into intermediate frequency signals, sampling the intermediate frequency signals through an intermediate frequency filter AD in the second radio frequency module and then transmitting the signals to the FFT module;
the FFT module is used for performing fast Fourier transform on the frequency hopping signal;
the signal detection module is used for receiving the time information sent by the GNSS receiver and detecting signals by adopting a sequence detection method;
the frequency sequence decoder is used for performing frequency sequence decoding on the detected differential frequency hopping sequence, and finally taking the decoded data information as output, and simultaneously demodulating the frequency transfer function G distributed to the node by the central control unit in the decoded data information n And apply the G n The function is updated to the frequency transfer function at the current time of the node.
4. A frequency hopping communication method based on the GNSS assisted trunked cooperative differential frequency hopping communication system according to claim 3, comprising the steps of:
s1: at the update time, the central control unit generates a space-time differential frequency hopping G function cluster { G }, according to the current frequency hopping frequency and the position information of each node 1 ,C 2 ,…,G n ,…,G N And will correspond to G n The function is distributed to the corresponding node n;
s2: the transmitting unit of each node uses the received G n The function is used for processing the input data and the frequency of the last hop, generating a differential frequency hopping signal of the current hop and transmitting the differential frequency hopping signal through a transmitting antenna;
s3: the receiving unit of each node receives the differential frequency hopping signal through the receiving antenna, detects and decodes the differential frequency hopping signal, and simultaneously demodulates the frequency transfer function G distributed to the node by the central control unit in the data information obtained by decoding n And apply the G n The function is updated to the G function at the current time of the node.
5. The method for frequency hopping communications in a GNSS assisted trunked cooperative differential frequency hopping communications system according to claim 4, wherein step S1 specifically comprises:
s1.1: let T be the updated time interval, at TAt times of integer multiple, each node will hop the current frequency f n And current position information P n A frequency set allocator sent to the central control unit;
s1.2: the frequency set distributor divides the differential frequency hopping frequency set M into N different frequency subsets according to the current frequency hopping frequency set and the current position information set which are sent by the node;
s1.3: the frequency set distributor respectively transmits N different frequency subsets to N corresponding G function generators;
s1.4: the frequency set distributor randomly distributes G functions of different types for the N G function generators;
s1.5: the central control unit distributes corresponding G functions for each node respectively, and the central control unit outputs a series of space-time variable G function clusters;
s1.6: and updating the current frequency hopping frequency and the current position information once by each node according to a fixed time interval T, reporting the current frequency hopping frequency and the current position information to the central control unit again, and then sequentially repeating the steps S1.1 to S1.5, and dynamically updating to generate a series of new space-time variable G function clusters.
6. The method for frequency hopping communications in a GNSS assisted trunked cooperative differential frequency hopping communications system according to claim 5, wherein step S1.2 specifically comprises:
s1.2.1: the frequency set distributor draws space-time occupation grid diagrams of all nodes according to the position information set and the time information set reported by the nodes;
s1.2.2: calculating the distance P between every two nodes i,j I and j respectively represent a node i and a node j, namely, the distance between any two nodes is normalized by the maximum value of the distances in every two nodes;
s1.2.3: dividing frequency subsets according to the principle that the closer the distance between two nodes is, the larger the frequency interval is;
s1.2.4: frequency set allocator reports frequency hopping frequency set { f } to node 1 ,f 2 ,…,f N Monitor.
7. The method according to claim 4, wherein in step S1.4, the different types of G functions include: any one of a G function based on a linear congruence theory, a G function based on chaotic mapping, a G function based on an encryption algorithm and a G function of time-frequency disturbance.
8. The method of claim 5, wherein in step S1.6, when the number of nodes changes, the central control unit can re-divide different frequency subsets and change G according to the increase or decrease of the position information reported by the nodes n The number of functions.
9. The method for frequency hopping communication of the GNSS assisted trunked cooperative differential frequency hopping communication system according to claim 4, wherein the step S2 specifically comprises:
s2.1: the buffer carries out data frame reorganization on the input information data and the position information output by the GNSS receiver, adds the position information into the frame head part of the data frame, and transmits the data in a framing mode;
s2.2: the GNSS receiver in the node inputs time information to G of the node n Function controls the accurate time of generation of the hopping sequence, G n The function decides the frequency of the current jump together by the frequency of the previous jump and the information symbol needed to be loaded by the current jump;
s2.3: the frequency synthesizer generates a differential frequency hopping frequency point according to the current frequency hopping frequency and sends the differential frequency hopping frequency point to the first radio frequency module;
s2.4: the first radio frequency module converts the differential frequency hopping frequency point into a differential frequency hopping signal through a transmitting antenna and sends the differential frequency hopping signal to a receiving unit of another node in the network.
10. The method for frequency hopping communication of the GNSS assisted trunked cooperative differential frequency hopping communication system according to claim 4, wherein the step S3 specifically comprises:
s3.1: the receiving antenna transmits the received signal to the second radio frequency module;
s3.2: the second radio frequency module down-converts the signal into an intermediate frequency signal, and the intermediate frequency signal is sampled by an intermediate frequency filter AD in the second radio frequency module and then transmitted to the FFT module;
s3.3: the FFT module performs fast Fourier transform on the intermediate frequency signal;
s3.4: the GNSS receiver inputs the time information to a signal detection module, and the signal detection module detects the FFT-transformed signals by adopting a sequence detection method;
s3.5: the frequency sequence decoder performs frequency sequence decoding on the differential frequency hopping sequence obtained by detection, finally takes the decoded data information as output, simultaneously demodulating the frequency transfer function G assigned to the node by the central control unit from the decoded data information n And apply the G n The function is updated to the G function at the current time of the node.
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