A multi-carrier based autonomous variable parameter communication method and system

Abstract

The present invention belongs to the field of wireless communication technology, and discloses a multi-carrier based autonomous parameter-varying communication method and system. In the present invention, both communication parties perform spectrum sensing, screen out idle channels and divide them into several sub-channels; write the center frequency points of the communication frequency bands of multi-carrier signals into the feature parameter set, and both communication parties establish a two-way communication link based on the feature parameter set; both communication parties perform parameter-varying communication according to the parameter-varying duration. In each parameter-varying communication, update the feature parameter set, and write the center frequency points of the new multi-carrier signal communication frequency bands, the frequency band information of the sub-carriers corresponding to each sub-channel, and the configuration information; both communication parties send and receive multi-carrier signals containing pilot sequences based on the feature parameter set, and calculate the bit error rate of the sub-carriers based on the pilot sequences; both communication parties exchange bit error rate information, and configure each sub-carrier in combination with the feature parameter set to achieve parameter-varying communication. The present invention can significantly improve the reliability of the wireless communication system.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and more specifically, relates to a multi-carrier based autonomous variable parameter communication method and system. Background Art

[0002] Cognitive frequency hopping systems are based on spectrum sensing technology, which organically combines spectrum busy / idle information with frequency hopping communication to achieve a dynamically adaptable transmission scheme. This scheme can effectively avoid external interference by adjusting transmission parameters, thereby improving the reliability of the communication system. However, traditional cognitive frequency hopping systems can only change the frequency point information in the signal characteristic parameters singly and cannot adapt to complex and time-varying electromagnetic spectrum environments. At the same time, multi-carrier modulation can decompose a broadband carrier into multiple independent narrowband sub-carriers, and each sub-carrier can be independently configured with parameters. Therefore, combining multi-carrier modulation with cognitive frequency hopping technology is expected to further enhance the robustness of cognitive frequency hopping systems.

[0003] In traditional cognitive systems, the spectrum sensing method usually uses a hard decision method. When this rough sensing method for channels is applied to multi-carrier signals, some sub-carriers in the multi-carrier signals will match the occupied channels, which will lead to information loss and even cause communication interruption. In addition, with the rapid growth of the number of users, spectrum resources are becoming increasingly scarce, and it is more difficult to find idle communication channels that meet the hard decision conditions. Summary of the Invention

[0004] The present invention provides a multi-carrier based autonomous variable parameter communication method and system to solve the problem in the prior art that communication between two parties in variable parameter communication is prone to communication interruption due to interference and the reliability of wireless communication needs to be improved.

[0005] The present invention provides a multi-carrier based autonomous variable parameter communication method, including the following steps:

[0006] Two communication parties perform spectrum sensing, screen out idle channels as the communication frequency band of the multi-carrier signal according to the available communication frequency band, the bandwidth of the multi-carrier signal, and the preset number of sub-carriers, and divide the idle channels into several sub-channels; write the center frequency point of the communication frequency band of the multi-carrier signal into the characteristic parameter set, and the two communication parties establish a two-way communication link based on the characteristic parameter set;

[0007] The two communication parties perform variable-parameter communication according to the variable-parameter duration. In each variable-parameter communication, the characteristic parameter set is updated, and the center frequency of the new multi-carrier signal communication frequency band, the frequency band information of the sub-carriers corresponding to each sub-channel, and the configuration information are written; the two communication parties send and receive multi-carrier signals containing pilot sequences based on the characteristic parameter set, and calculate the bit error rate of the sub-carriers corresponding to each sub-channel based on the pilot sequences; the two communication parties exchange bit error rate information, configure each sub-carrier according to the bit error rate information and in combination with the characteristic parameter set, and perform variable-parameter communication using the multi-carrier signal waveform composed of the configured sub-carriers.

[0008] Preferably, the configuration information includes the modulation method, transmission power, and usage status of the sub-carrier corresponding to the bit error rate of the sub-carrier; the usage status includes two statuses: carrying information and not carrying information.

[0009] Preferably, screening for idle channels includes: dividing the available communication frequency band into several channels, each channel having the same bandwidth as the multi-carrier signal. The two communication parties perform spectrum sensing on each channel, sample and collect information in each channel respectively, obtain the amplitude matrix corresponding to the sampling information through fast Fourier transform, obtain the average energy value of each channel according to the amplitude matrix, and select the channel with the smallest average energy value as the idle channel.

[0010] Preferably, the number of divided sub-channels is equal to the preset number of sub-carriers. When the multi-carrier signal is orthogonal frequency division multiplexing, the number of divided channels is calculated using the following formula: ; the bandwidth of the sub-channel is calculated using the following formula: ; where is the number of channels, is the available communication frequency band bandwidth, is the spectrum sensing step factor, is the bandwidth of the sub-channel, is the bandwidth of the multi-carrier signal, is the preset number of sub-carriers.

[0011] Preferably, the two communication parties establish a two-way communication link based on the characteristic parameter set, including:

[0012] The calling party among the two communication parties generates a first characteristic parameter set and a second characteristic parameter set through spectrum sensing, where the first characteristic parameter set is used for the calling party to configure the transmitted signal; the calling party encapsulates the second characteristic parameter set and the variable-parameter moment into the information and sends it;

[0013] The answering party among the two communication parties performs spectrum sensing and The identifier analyzes the information it receives and extracts the second set of characteristic parameters. , and based on the second set of characteristic parameters , configures the signal transmitted by the responder. Meanwhile, the responder generates a third set of characteristic parameters through spectrum sensing , and encapsulates the third set of characteristic parameters into the information and sends it;

[0014] The calling party performs matching reception of information at the frequency point corresponding to the second set of characteristic parameters , extracts the third set of characteristic parameters , and the calling party and the responder successfully establish a two-way communication link.

[0015] Preferably, when the two communication parties perform variable-parameter communication according to the variable-parameter duration, the starting moment of the variable-parameter communication is negotiated at the variable-parameter moment , and both communication parties use the starting moment of the variable-parameter communication as the starting moment of the variable-parameter communication.

[0016] Preferably, calculating the bit error rate of the subcarriers corresponding to each sub-channel based on the pilot sequence includes:

[0017] The two communication parties generate the same pilot sequence and evenly distribute it to each subcarrier according to the preset number of subcarriers;

[0018] One of the two communication parties sends a multi-carrier signal containing the pilot sequence in the channel corresponding to the extracted set of characteristic parameters;

[0019] The other of the two communication parties compares the received pilot sequence with the known pilot sequence, calculates the bit error rate of the subcarriers corresponding to each sub-channel, denoted as , where is the bit error rate sequence, is the bit error rate of the subcarrier corresponding to the n -th sub-channel, is the preset number of subcarriers.

[0020] Preferably, the two communication parties' interaction of bit error rate information includes: The calling party among the two communication parties adjusts the number and bandwidth of subcarriers according to the obtained bit error rate information, sets the subcarriers with a bit error rate of zero as available carriers, sets the subcarriers with a non-zero bit error rate as empty carriers, puts the set of characteristic parameters into the available carriers, and diversely sends them to the responder among the two communication parties; The responder sends the set of characteristic parameters to the calling party in the same manner as above.

[0021] Preferably, configuring each subcarrier according to the bit error rate information and in combination with the set of characteristic parameters includes:

[0022] ​Compare the bit error rate of the subcarriers corresponding to each sub-channel with the bit error rate threshold; wherein, the bit error rate threshold includes a first bit error rate threshold and a second bit error rate threshold , and less than ;

[0023] If the bit error rate of the subcarriers corresponding to a certain sub-channel is greater than or equal to , then regard this sub-channel as an occupied sub-channel, and set the subcarriers corresponding to the occupied sub-channel as null frequency subcarriers that do not transmit useful information;

[0024] If the bit error rate of the subcarriers corresponding to a certain sub-channel is less than and greater than or equal to , then regard this sub-channel as a first type of idle sub-channel, and the subcarriers corresponding to the first type of idle sub-channel adopt a low-order modulation method and are allocated a first transmission power;

[0025] If the bit error rate of the subcarriers corresponding to a certain sub-channel is less than , then regard this sub-channel as a second type of idle sub-channel, and the subcarriers corresponding to the second type of idle sub-channel adopt a high-order modulation method and are allocated a second transmission power;

[0026] Wherein, the low-order modulation method includes BPSK, the high-order modulation method includes QPSK, and the first transmission power is greater than the second transmission power.

[0027] On the other hand, the present invention provides a multi-carrier based autonomous variable parameter communication system, including:

[0028] A spectrum sensing module, configured to perform spectrum sensing on a communication channel, screen out idle channels, divide the idle channels into multiple sub-channels, generate a feature parameter set, and update the feature parameter set when a variable parameter period arrives;

[0029] A signal transceiver module, configured to send and receive signals;

[0030] A signal discrimination module, configured to check identify and analyze the feature parameter set;

[0031] A channel measurement module, configured to obtain the bit error rate of the subcarriers corresponding to each sub-channel;

[0032] A dynamic adjustment module, configured to exchange the bit error rate information of both communication parties, and configure each subcarrier according to the bit error rate information and in combination with the feature parameter set;

[0033] The multi-carrier based autonomous variable parameter communication system is used to execute the steps in the above-mentioned multi-carrier based autonomous variable parameter communication method.

[0034] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0035] When establishing a bidirectional communication link between two communication parties in the present invention, the two communication parties perform spectrum sensing, and according to the available communication frequency band, the bandwidth of the multi-carrier signal, and the preset number of sub-carriers, idle channels serving as the communication frequency band of the multi-carrier signal are screened out, and the idle channels are divided into several sub-channels. The central frequency point of the communication frequency band of the multi-carrier signal is written into the feature parameter set, and the two communication parties establish a bidirectional communication link based on the feature parameter set; when the two communication parties in the present invention enter the autonomous parameter-varying communication stage, the two communication parties perform parameter-varying communication according to the parameter-varying duration. In each parameter-varying communication, the feature parameter set is updated, and the central frequency point of the new communication frequency band of the multi-carrier signal, the frequency band information of the sub-carriers corresponding to each sub-channel, and the configuration information are written; the two communication parties send and receive multi-carrier signals including pilot sequences based on the feature parameter set, and calculate the bit error rate of the sub-carriers corresponding to each sub-channel based on the pilot sequences; the two communication parties exchange bit error rate information, configure each sub-carrier according to the bit error rate information and in combination with the feature parameter set, and perform parameter-varying communication using the multi-carrier signal waveform composed of the configured sub-carriers. That is, the present invention realizes that nodes improve the anti-interference ability of the wireless communication system through spectrum sensing technology and the real-time generation and autonomous update of the feature parameter set. By introducing bit error rate calculation and signal waveform design, narrowband interference existing in the communication channel can be avoided, a multi-carrier signal that fits the electromagnetic environment can be provided, the flexibility of multi-carrier communication is increased, and the spectrum utilization rate is improved. The present invention effectively solves the problem of communication interruption caused by interference of some sub-carriers during parameter-varying communication between two communication parties, and can significantly improve the reliability of the wireless communication system. Description of the Drawings

[0036] Figure 1 It is a specific communication flow chart of the calling party and the answering party in a multi-carrier-based autonomous parameter-varying communication method provided in Embodiment 1 of the present invention;

[0037] Figure 2 It is a spectrum and signal waveform diagram of the electromagnetic environment; wherein, Figure 2 (a) in it is the electromagnetic environment spectrum diagram in the entire communication frequency band, Figure 2 (b) in it is the multi-carrier signal waveform autonomously designed after spectrum sensing of the electromagnetic environment using a multi-carrier-based autonomous parameter-varying communication method provided in Embodiment 1 of the present invention, Figure 2 (c) in it is the signal waveform in which the designed multi-carrier signal coexists with the interference signal. Detailed Embodiments

[0038] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0039] Embodiment 1:

[0040] Embodiment 1 provides a multi - carrier - based autonomous parameter - varying communication method, including the following steps:

[0041] The two communication parties perform spectrum sensing, and according to the available communication frequency band, the bandwidth of the multi - carrier signal, and the preset number of sub - carriers, filter out idle channels as the communication frequency band of the multi - carrier signal, and divide the idle channels into several sub - channels; write the center frequency point of the multi - carrier signal communication frequency band into the characteristic parameter set, and the two communication parties establish a two - way communication link based on the characteristic parameter set.

[0042] The two communication parties perform parameter - varying communication according to the parameter - varying duration. In each parameter - varying communication, update the characteristic parameter set, and write the center frequency point of the new multi - carrier signal communication frequency band, the frequency band information of the sub - carriers corresponding to each sub - channel, and the configuration information; the two communication parties send and receive multi - carrier signals containing pilot sequences based on the characteristic parameter set, and calculate the bit error rate of the sub - carriers corresponding to each sub - channel based on the pilot sequences; the two communication parties exchange bit error rate information, configure each sub - carrier according to the bit error rate information and in combination with the characteristic parameter set, and perform parameter - varying communication using the multi - carrier signal waveform composed of the configured sub - carriers.

[0043] That is, the present invention mainly includes two stages: the stage where the two communication parties independently establish a two - way communication link and the stage where the two communication parties perform autonomous parameter - varying communication. Among them, in the stage where the two communication parties independently establish a two - way communication link, it mainly includes: the two communication parties divide the wireless channel into several channels and sub - channels; the two communication parties perform spectrum sensing to filter out idle channels, use multi - carrier signals to exchange information, and independently establish a two - way communication link. In the stage where the two communication parties perform autonomous parameter - varying communication, it mainly includes: the two communication parties simultaneously enter the autonomous parameter - varying communication stage, the two communication parties send and receive multi - carrier signals containing pilot sequences, compare the received pilot sequence with the known pilot sequence, and calculate the information bit error rate of each sub - channel; the two communication parties exchange bit error rate information; the two communication parties configure each sub - carrier, design a multi - carrier signal waveform adapted to the electromagnetic environment, and perform information interaction.

[0044] Specifically, the configuration information includes the modulation method, transmission power, and usage status of the sub - carrier corresponding to the bit error rate of the sub - carrier; the usage status includes two states: carrying information and not carrying information.

[0045] Among them, screening for idle channels includes: dividing the available communication frequency band into several channels, each with a bandwidth equal to that of the multi-carrier signal. Both communication parties perform spectrum sensing on each channel, sample and collect information in each channel respectively, obtain the amplitude matrix corresponding to the sampling information through fast Fourier transform, obtain the average energy value of each channel based on the amplitude matrix, and select the channel with the smallest average energy value as the idle channel.

[0046] Specifically, the following formula is used to calculate the average energy value:

[0047]

[0048] In the formula, represents the average energy value of the th channel, represents the number of sampling points, represents the th channel, and represents the magnitude of the

[0049] th time-domain sampling point in the th channel after fast Fourier transform. In the formula, is the number of channels, is the available communication frequency band bandwidth, is the spectrum sensing step factor, is the bandwidth of the sub-channel, is the bandwidth of the multi-carrier signal, is the preset number of sub-carriers.

[0050] Among them, establishing a two-way communication link between the communication parties based on the characteristic parameter set includes: the calling party among the communication parties generates a first characteristic parameter set and a second characteristic parameter set through spectrum sensing. Among them, the first characteristic parameter set is used for the calling party to configure the transmitted signal; the calling party encapsulates the second characteristic parameter set and the variable parameter moment into the information and sends it; the answering party among the communication parties resolves the information it receives through spectrum sensing and identification, extracts the second characteristic parameter set , and based on the second characteristic parameter set Configure the responder to transmit a signal, and at the same time, the responder generates a third set of characteristic parameters through spectrum sensing and encapsulates the third set of characteristic parameters into the information for transmission; the calling party performs matching reception of the information at the frequency point corresponding to the second set of characteristic parameters and extracts the third set of characteristic parameters , and the calling party and the responder successfully establish a two-way communication link.

[0051] Among them, when the two communication parties perform variable-parameter communication according to the variable-parameter duration, the variable-parameter start time is negotiated, and the two communication parties both use the variable-parameter start time as the variable-parameter start time. The signal parameters sent by the calling party and the signal parameters received by the responder at the variable-parameter start time are generated during the link establishment process , and the signal parameters received by the calling party and the signal parameters sent by the responder at the variable-parameter start time are generated during the link establishment process . .

[0052] Specifically, calculating the bit error rate of the subcarriers corresponding to each sub-channel based on the pilot sequence includes: the two communication parties generate the same pilot sequence and evenly distribute it to each sub-carrier according to the preset number of sub-carriers; one of the two communication parties sends a multi-carrier signal containing the pilot sequence in the channel corresponding to the extracted set of characteristic parameters; the other of the two communication parties compares the received pilot sequence with the known pilot sequence and calculates the bit error rate of the sub-carriers corresponding to each sub-channel, denoted as , where is the bit error rate sequence, is the bit error rate of the sub-carrier corresponding to the n th sub-channel, is the preset number of sub-carriers.

[0053] That is, the calling party sends a multi-carrier signal with a pilot sequence in the selected channel, and the responder compares the received pilot sequence with the known pilot sequence and calculates the information bit error rate of each sub-channel; similarly, the responder sends a multi-carrier signal with a pilot sequence in the channel it selects for the calling party to calculate the bit error rate.

[0054] Specifically, the two communication parties' interaction of bit error rate information includes: the calling party among the two communication parties adjusts the number and bandwidth of sub-carriers according to the obtained bit error rate information, sets the sub-carriers with a bit error rate of zero as available carriers, sets the sub-carriers with a non-zero bit error rate as empty carriers, and puts the set of characteristic parameters into the available carriers by means of diversity and sends it to the responder among the two communication parties; similarly, the responder sends the set of characteristic parameters to the calling party in the same way as above.

[0055] Specifically, configuring each subcarrier according to the bit error rate information and in combination with the characteristic parameter set includes: comparing the bit error rate of the subcarriers corresponding to each sub-channel with a bit error rate threshold; wherein, the bit error rate threshold includes a first bit error rate threshold and a second bit error rate threshold , and is less than ; , is affected by the communication distance and the ability of the receiving system to correct error bits information. If the bit error rate of the subcarriers corresponding to a certain sub-channel is greater than or equal to , then regard the sub-channel as an occupied sub-channel. Such channels exceed the error correction ability of the receiving system and cannot restore information, and set the subcarriers corresponding to the occupied sub-channel as empty frequency subcarriers that do not transmit useful information. If the bit error rate of the subcarriers corresponding to a certain sub-channel is less than and greater than or equal to , then regard the sub-channel as a type of idle sub-channel. The subcarriers corresponding to the type of idle sub-channel adopt a low-order modulation method and are allocated a first transmission power; that is, a low-order modulation method is adopted in such sub-channels and a relatively high transmission power is allocated to improve the transmission ability. If the bit error rate of the subcarriers corresponding to a certain sub-channel is less than , then regard the sub-channel as a second type of idle sub-channel. The communication status of such sub-channels is good. The subcarriers corresponding to the second type of idle sub-channel adopt a high-order modulation method and are allocated a second transmission power. Among them, the low-order modulation method includes BPSK, the high-order modulation method includes QPSK, and the first transmission power is greater than the second transmission power.

[0056] That is, both communication parties configure each subcarrier according to the obtained bit error rate information according to the above strategy, design a multi-carrier signal waveform adapted to the electromagnetic environment and perform information interaction.

[0057] In the present invention, if the communication is normal, the autonomous variable parameter communication process is repeated. If the communication is abnormally interrupted, a two-way communication link is re-established. Both communication parties of the present invention will perform spectrum sensing to update the characteristic parameter set. Specifically, the present invention will obtain the characteristic parameters of the next time slot in both the two-way communication link establishment stage and the autonomous variable parameter communication stage. The present invention uses a pre-announcement method to negotiate the parameters of the next time slot and then perform the next frequency hopping communication.

[0058] Both communication parties perform spectrum sensing to update the characteristic parameter set, which specifically includes: both communication parties autonomously generate their own received signal characteristic parameter sets at the next variable parameter moment through spectrum sensing , and the other party uses this to update the parameters of the signal to be sent at its next variable parameter moment, and at the same time update the variable parameter moment Based on the signal feature parameter set, both communication parties dynamically adjust the signal parameters and repeat the above operations. If the communication is abnormally interrupted, a two-way communication link is re-established.

[0059] Overall, in the present invention, first, both communication parties divide the wireless channel into several channels and sub-channels according to the available communication frequency band, the multi-carrier signal bandwidth, and the preset number of sub-carriers, and select idle channels through spectrum sensing. Secondly, the calling party autonomously establishes a two-way communication link with the answering party through a call response mechanism, and simultaneously obtains the signal feature parameter set of the next time slot. Then, both communication parties enter the autonomous parameter-varying communication stage, calculate the information bit error rate of each sub-channel according to the signal feature parameter set, and configure parameters such as the modulation mode of each sub-carrier according to the calculation results, and design a multi-carrier signal waveform adapted to the electromagnetic environment. Finally, both communication parties perform parameter-varying communication according to the designed waveform, and autonomously update the signal feature parameter set of the next time slot through spectrum sensing.

[0060] It can also be understood that the idle channels screened by spectrum sensing in the present invention have a bandwidth equal to the total bandwidth of the transmitted multi-carrier signal, that is, the present invention transmits the entire multi-carrier signal in the idle channels. The multi-carrier signal has multiple sub-carriers, and the specific frequency band corresponding to each sub-carrier in the selected idle channel is a sub-channel. The present invention first selects idle channels. When the spectrum environment is relatively complex, the selected idle channels only have relatively low average energy, but it cannot be ensured that the energy values are low everywhere in this section of the channel, and there may be narrowband interference. At this time, it is necessary to divide sub-channels in this channel to find out the unavailable sub-channels in this section of the channel. At this time, the sub-channels correspond to the respective sub-carriers in the multi-carrier signal. When judging whether a sub-channel is available at this time, a method of calculating the bit error rate of each sub-channel is adopted, which can accurately calculate the situation of the sub-channel corresponding to each sub-carrier, and is convenient for subsequent multi-carrier waveform design.

[0061] The method proposed in the present invention aims at a complex electromagnetic environment with narrowband interference, and updates the sub-carrier configuration in real time according to the channel conditions, realizing multi-carrier autonomous parameter-varying communication against narrowband interference, and effectively improving the spectrum utilization rate and anti-interference performance of the proposed system.

[0062] Embodiment 2:

[0063] Embodiment 2 provides a multi-carrier-based autonomous parameter-varying communication system, including:

[0064] A spectrum sensing module, configured to perform spectrum sensing on a communication channel, screen out idle channels, divide the idle channels into multiple sub-channels, generate a feature parameter set, and update the feature parameter set when a parameter-varying period arrives;

[0065] A signal transceiver module, configured to send and receive signals;

[0066] A signal discrimination module for verifying the identification and parsing feature parameter set;

[0067] A channel measurement module for obtaining the bit error rate of subcarriers corresponding to each subchannel;

[0068] A dynamic adjustment module for exchanging the bit error rate information of both communication parties and configuring each subcarrier according to the bit error rate information and in combination with the feature parameter set;

[0069] The multi - carrier - based autonomous variable - parameter communication system provided in Embodiment 2 is used to execute the steps in the multi - carrier - based autonomous variable - parameter communication method described in Embodiment 1.

[0070] The combined working process of each module in the multi - carrier - based autonomous variable - parameter communication system is as follows: First, both communication parties enter the stage of autonomously establishing a two - way communication link. The calling party generates a feature parameter set through the spectrum sensing module, sends information through the signal transceiver module and silently receives. Second, the answering party generates a feature parameter set through the spectrum sensing module, obtains the calling party's feature parameter set through the signal transceiver module and the signal discrimination module, and sends the generated feature parameter set through the signal transceiver module. After that, the calling party obtains the answering party's feature parameter set through the signal transceiver module and the signal discrimination module. Thus, both communication parties successfully establish a two - way communication link. Then, both communication parties enter the stage of autonomous variable - parameter communication, send a pilot sequence through the signal transceiver module; calculate the bit error rate of the subchannel using the channel measurement module, interact the bit error rate information with the help of the signal transceiver module, and configure each subcarrier by the dynamic adjustment module to obtain a multi - carrier signal waveform adapted to the electromagnetic environment. Finally, signal transmission and reception are performed through the signal transceiver module and the signal discrimination module. If a useful signal is found in a variable - parameter time slot (i.e., the communication is normal), the spectrum sensing module is used to generate the feature parameter set for the next time slot and return to the variable - parameter communication stage for variable - parameter communication in the next time slot; if no useful signal is found (i.e., the communication is abnormally interrupted), return to the stage of establishing a two - way communication link.

[0071] Since the functions of each module in the multi - carrier - based autonomous variable - parameter communication system provided in Embodiment 2 correspond to the steps in the multi - carrier - based autonomous variable - parameter communication method provided in Embodiment 1, Embodiment 2 can also be understood by referring to the description of Embodiment 1, and will not be elaborated here.

[0072] Next, the multi - carrier - based autonomous variable - parameter communication method provided by the present invention is applied to a wireless communication system composed of multiple communication nodes and interference nodes, and examples are given in combination with parameters.

[0073] Overall, the communication process mainly includes channel division, sensing and selection processes, the user call response and independent link establishment process, the process of calculating the information bit error rate of sub-channels, the waveform design process, and the independent variable parameter communication process.

[0074] After the system initializes and runs, each node defaults to a silent receiving state of full-band frequency scanning. The calling party independently selects a set of characteristic parameters according to the real-time state of the wireless spectrum environment, and the answering party independently identifies the set of signal characteristic parameters through spectrum sensing for matching reception. The two communication parties establish an independent link through the call response mechanism.

[0075] The two communication parties perform state transitions, calculate the information bit error rate of sub-channels according to the set of signal characteristic parameters and pilot sequences, and exchange the obtained results. The two communication parties adjust the power allocation (high and low power), modulation mode (low-order and high-order modulation), and information-carrying capacity (when using different-order modulation modes, the total bit amount of information carried by each sub-carrier is different. For example, the number of QPSK bits is twice that of BPSK bits, and the number of bits of sub-carriers that do not send useful information is 0) of their corresponding sub-carriers according to the information bit error rate of each sub-channel, and design a multi-carrier signal waveform adapted to the electromagnetic environment. The two communication parties update the set of signal characteristic parameters in real time in each variable parameter time slot, and complete independent variable parameter communication based on this standard.

[0076] The specific data fields transmitted by the two communication parties include: Identifiers (including the calling party identifier and the answering party identifier ), variable parameter time transmitted data and the set of signal characteristic parameters . The calling party identifier and the answering party identifier are used for verifying the identities of the two communication parties; the variable parameter time is used to negotiate the starting time of variable parameter communication between the two communication parties; the transmitted data represents the information content to be transmitted by the two communication parties; the set of signal characteristic parameters is used to coordinate the parameter configuration of the two communication parties, including the center frequency point of the multi-carrier signal, the sub-channel bit error rate information, the modulation mode, and the usage status, and encapsulates the above characteristic parameters uniformly.

[0077] For example, a wireless communication system consisting of a sending node, a receiving node, and three interfering nodes is built using a software-defined radio device USRP-2920 and LabVIEW software. This system is fully distributed, that is, the system consists of a series of arbitrarily movable communication nodes, the nodes are dynamically and arbitrarily distributed, there is no control center and common control channel in the system, all nodes are equal in status, and no other pre-set network facilities are required. It can establish a link autonomously and carry out variable-parameter communication at any time and place. The system composition is as follows: communication nodes (USRP-A is the responder, USRP-B is the caller), and each node has the ability to send and receive information. USRP-C, USRP-D, and USRP-E are used as interfering nodes, and send narrowband interference 1, narrowband interference 2, and narrowband interference 3 with different gain sizes in three different frequency bands respectively. The distance between the two communicating parties is 50 cm, and the three interfering sources are placed around at a position 25 cm away from the two communicating parties. That is, the five devices are, from left to right, narrowband interference 3, communication node, narrowband interference 2, communication node, narrowband interference 1.

[0078] Specifically, refer to Figure 1 , and the communication steps include:

[0079] Step 1: System initialization and operation: After the system starts, it enters the initialization state. By default, all communication nodes are in the silent frequency scanning and receiving state after power-on. In this state, the system divides and senses the frequency band according to the available communication frequency band , the bandwidth of the multi-carrier signal of 5 MHz, and the preset number of sub-carriers of 64, calculates the energy values of each channel, records the idle channels and occupied channels, and if the information of a legitimate user is detected or a call needs to be initiated in the occupied channels, it transfers to the information sending state.

[0080] Step 2: User initiates a call: When the user presses the send key of the communication node to change the system state to the information sending state, this communication node becomes the caller. The of the caller is set to 100, is set to 200. The caller performs spectrum sensing within the set frequency band range and generates a feature parameter set and . Among them, is used for the caller to configure the transmitted signal, encapsulates the feature parameter set into the transmitted information for the responder to configure the transmitted signal, and at the same time encapsulates the variable-parameter moment according to the user's needs to ensure that both parties enter the variable-parameter communication stage simultaneously. Finally, the caller enters the frequency scanning and receiving state and performs real-time detection and reception at the frequency points corresponding to the feature parameter set .

[0081] Step 3, User Matching Response: When the user detects the information of a legitimate user in the silent frequency scanning and receiving state and then enters the information sending state, this communication node acts as the responder. When the responder performs silent reception, set to 200, set to 100. The responder autonomously identifies the characteristic parameter set of the signal sent by the caller , after matching and receiving, parses the received information, and extracts the other party's and its own for comparison. If the match is successful, the remaining data is parsed. Among them, the characteristic parameter set serves as the characteristic parameter set of the signal sent by the responder. At the same time, it performs spectrum sensing on the frequency band range set by the system and autonomously generates a characteristic parameter set , which serves as the characteristic parameter set for the responder to receive signals in the next time slot and the characteristic parameter set of the signal sent by the caller. After that, the characteristic parameter set is encapsulated and the information is sent.

[0082] Step 4, Synchronous Transfer of Communication State: After the caller performs matching reception at the frequency point corresponding to the characteristic parameter set , it extracts . After that, the caller enters the waiting state and synchronously enters the variable parameter communication stage with the responder.

[0083] At this point, it indicates that the caller and the responder have successfully established a two-way communication link. Then, both parties synchronously enter the autonomous variable parameter communication stage. In this stage, variable parameter communication is carried out according to the variable parameter duration preset by the user, and the status of both parties is equal, and the operations performed are the same.

[0084] Step 5, Calculation of Information Bit Error Rate of the Channel: Both communication parties generate the same pilot sequence group and evenly distribute it to 64 subcarriers. The caller transmitter sends a multi-carrier signal according to the characteristic parameter set . After the responder receiver receives it, it compares the pilot sequences in each subcarrier and calculates the information bit error rate of each subcarrier. Similarly, the responder transmitter and the caller receiver calculate the information bit error rate of the channel according to the characteristic parameter set .

[0085] Step 6, Interaction of Bit Error Rate Information: Both communication parties autonomously update the characteristic parameter set, then set the number of subcarriers to 4, set the carriers with zero bit error rate as available carriers, and finally put the characteristic parameter set into the available carriers and send it by means of diversity. After the receiver receives it, it separates the information in each subcarrier and finds the information bit error rate sequence of the channel.

[0086] Step 7, Subcarrier Configuration: The two communication parties classify each subcarrier according to the bit error rate threshold sequence and set the subcarriers corresponding to the sub-channels with a bit error rate greater than 0.1 as occupied sub-channels and set the subcarriers corresponding to such sub-channels as null frequency; the sub-channels with a bit error rate greater than 0 and less than 0.1 are regarded as a type of idle sub-channels, and the transmit power of the carriers corresponding to this type of sub-channels is increased by 1 time, and at the same time, the modulation method is set to BPSK; the sub-channels with a bit error rate equal to 0 are regarded as the second type of idle sub-channels, and a large amount of information is transmitted through the carriers corresponding to such sub-channels, and the modulation method is set to QPSK. Then, the two communication parties distribute the information to each subcarrier according to the above strategy for transmission and reception.

[0087] Step 8, Autonomous Update of the Feature Parameter Set: Perform spectrum sensing every other variable parameter period T, and autonomously generate the feature parameter set 583 MHz at the next variable parameter moment according to the sensing result, which is used to configure the received signal and write it into and inform the other party. The other party uses this feature parameter set to configure the transmitted signal, and then transfers to Step 5 for variable parameter communication in the next time slot until the user actively stops the communication.

[0088] The calling party and the answering party communicate using the above communication method.

[0089] In addition, in the present invention, the multi-carrier signal uses orthogonal frequency division multiplexing, that is, the OFDM signal, and the number of OFDM subcarriers, the system bandwidth, and the modulation method are set, as shown in Table 1. At the same time, the transmission frequency point, modulation method, waveform, IQ sampling rate, and transmission gain of the narrowband interference are set. The electromagnetic environment of the communication frequency band and the multi-carrier signal waveforms of the two communication parties are obtained by a spectrum analyzer, as Figure 2 shown. The method provided by the present invention is compared and tested with the same type of method (a multi-carrier frequency hopping system that only changes the communication center frequency point). The test process is carried out 3000 times, and 448-bit information is transmitted and received each time. Specifically, Figure 2 Figure (a) in Figure 2 is the electromagnetic environment spectrum diagram in the entire communication frequency band. As shown in the figure, there are three narrowband interferences, and the specific parameters are shown in Table 2. Figure 2 Figure (b) in

[0090] is the multi-carrier signal waveform independently designed by the method provided by the present invention after spectrum sensing of the electromagnetic environment. As shown in the figure, the subcarriers affected by the interference are set as null frequency, specifically manifested as signal dips, and such subcarriers do not carry any useful information.

[0091]

[0092] Table 2 Narrowband interference signal configuration

[0093]

[0094] Table 3 Performance comparison between the multi-carrier based autonomous parameter-varying communication system provided by the present invention and the traditional multi-carrier frequency hopping system

[0095]

[0096] As can be seen from the results in Table 3, the bit error rate of the present invention is significantly reduced. Compared with the traditional multi-carrier autonomous parameter-varying communication system, the multi-carrier based autonomous parameter-varying communication system proposed by the present invention has obvious advantages and enhances the transmission reliability of communication.

[0097] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An autonomous variable parameter communication method based on multi-carriers, characterized in that It includes the following steps: Both communication parties perform spectrum sensing, filter out idle channels as the communication frequency band of the multi-carrier signal according to the available communication frequency band, the bandwidth of the multi-carrier signal, and the preset number of sub-carriers, and divide the idle channels into several sub-channels; write the center frequency point of the communication frequency band of the multi-carrier signal into the feature parameter set, and both communication parties establish a two-way communication link based on the feature parameter set; Both communication parties perform variable-parameter communication according to the variable-parameter duration. In each variable-parameter communication, update the feature parameter set, and write the center frequency point of the new multi-carrier signal communication frequency band, the frequency band information of the sub-carriers corresponding to each sub-channel, and the configuration information; the configuration information includes the modulation method, transmit power, and usage status of the sub-carrier corresponding to the bit error rate of the sub-carrier; the usage status includes two states: carrying information and not carrying information; both communication parties send and receive multi-carrier signals containing pilot sequences based on the feature parameter set, and calculate the bit error rate of the sub-carriers corresponding to each sub-channel based on the pilot sequence; both communication parties exchange bit error rate information, configure each sub-carrier according to the bit error rate information and in combination with the feature parameter set, and perform variable-parameter communication using the multi-carrier signal waveform composed of the configured sub-carriers; Configuring each sub-carrier according to the bit error rate information and in combination with the feature parameter set includes: Compare the bit error rate of the subcarriers corresponding to each subchannel with a bit error rate threshold; wherein, the bit error rate threshold includes a first bit error rate threshold and a second bit error rate threshold , and is less than ; If the bit error rate of the subcarriers corresponding to a certain subchannel is greater than or equal to , then the subchannel is regarded as an occupied subchannel, and the subcarriers corresponding to the occupied subchannel are set to null frequency subcarriers that do not transmit useful information; If the bit error rate of the subcarriers corresponding to a certain subchannel is less than and greater than or equal to , then this subchannel is regarded as a type of idle subchannel, and the subcarriers corresponding to the type of idle subchannel adopt a low-order modulation method and are allocated a first transmission power; If the bit error rate of the subcarriers corresponding to a certain subchannel is less than , then the subchannel is regarded as a type-II idle subchannel, and the subcarriers corresponding to the type-II idle subchannel adopt a high-order modulation method and are allocated a second transmission power; Among them, the low-order modulation method includes BPSK, the high-order modulation method includes QPSK, and the first transmit power is greater than the second transmit power.

2. The multi-carrier based autonomous variable parameter communication method according to claim 1, wherein Filtering out idle channels includes: dividing the available communication frequency band into several channels, each channel having the same bandwidth as the multi-carrier signal. Both communication parties perform spectrum sensing on each channel, perform sampling and information collection in each channel respectively, obtain the amplitude matrix corresponding to the sampling information through fast Fourier transform, obtain the average energy value of each channel according to the amplitude matrix, and select the channel with the smallest average energy value as the idle channel.

3. The multi-carrier based autonomous variable parameter communication method according to claim 2, wherein The number of divided sub-channels is equal to the preset number of sub-carriers. When the multi-carrier signal is orthogonal frequency division multiplexing, the number of divided channels is calculated using the following formula: ; The bandwidth of the sub-channel is calculated using the following formula: ; In the formula, is the number of channels, is the available communication frequency band bandwidth, is the spectrum sensing step factor, is the bandwidth of the sub-channel, is the bandwidth of the multi-carrier signal, is the preset number of sub-carriers.

4. The multi-carrier based autonomous variable parameter communication method according to claim 1, wherein Both communication parties establishing a two-way communication link based on the feature parameter set includes: The calling party among the two communication parties generates a first set of characteristic parameters through spectrum sensing and a second set of characteristic parameters , wherein, the first set of characteristic parameters is used for the calling party to configure the transmitted signal; the calling party encapsulates the second set of characteristic parameters and the variable parameter moment into the information and sends it The responder in the communication uses spectrum sensing and The identifier parses the received information and extracts the second characteristic parameter set , and according to the second characteristic parameter set Configure the responder to transmit a signal, and the responder generates a third characteristic parameter set through spectrum sensing , and the third characteristic parameter set Encapsulate into information and send; The calling party matches and receives information at the corresponding frequency points of the second feature parameter set and extracts the third feature parameter set , and a two-way communication link is successfully established between the calling party and the answering party.

5. The multi-carrier-based autonomous variable parameter communication method according to claim 4, wherein When the two communication parties perform variable-parameter communication according to the variable-parameter duration, the variable-parameter moment negotiates the start moment of the variable-parameter communication , and both communication parties use the start moment of the variable-parameter communication as the start moment of the variable-parameter communication.

6. The multi-carrier based autonomous variable parameter communication method according to claim 1, wherein Calculating the bit error rate of the sub-carriers corresponding to each sub-channel based on the pilot sequence includes: Both communication parties generate the same pilot sequence and evenly distribute it to each sub-carrier according to the preset number of sub-carriers; One of the communication parties sends a multi-carrier signal containing the pilot sequence in the channel corresponding to the extracted feature parameter set; The other party among the two communication parties compares the received pilot sequence with a known pilot sequence, calculates the bit error rate of the subcarriers corresponding to each subchannel, and records it as , where is the bit error rate sequence,[[]] is the bit error rate of the subcarriers corresponding to the n th subchannel,[[]] is the preset number of subcarriers.

7. The multi-carrier based autonomous variable parameter communication method according to claim 1, characterized in that, Both communication parties exchanging bit error rate information includes: the calling party among the two communication parties adjusts the number and bandwidth of the sub-carriers according to the obtained bit error rate information, sets the sub-carriers with a bit error rate of zero as available carriers, sets the sub-carriers with a non-zero bit error rate as empty carriers, puts the feature parameter set into the available carriers, and diversely transmits it to the answering party among the two communication parties; the answering party sends the feature parameter set to the calling party in the same manner as above.

8. A multi-carrier based autonomous variable parameter communication system, characterized in that, It includes: A spectrum sensing module, which is used to perform spectrum sensing on the communication channel, filter out idle channels, divide the idle channels into multiple sub-channels, generate a feature parameter set, and update the feature parameter set when the variable-parameter period arrives; A signal transceiver module, which is used to send and receive signals; A signal discrimination module for verifying the identification and parsing of the characteristic parameter set; A channel measurement module, which is used to obtain the bit error rate of the sub-carriers corresponding to each sub-channel; A dynamic adjustment module is used to exchange the bit error rate information of both communication parties and configure each subcarrier according to the bit error rate information and in combination with a feature parameter set. The multi-carrier based autonomous variable parameter communication system is used to execute the steps in the multi-carrier based autonomous variable parameter communication method according to any one of claims 1-7.

Images