Autonomous variable parameter communication method and system based on multiple carriers

Abstract

The invention belongs to the technical field of wireless communication, and discloses an autonomous variable parameter communication method and system based on multiple carriers. The method comprises the following steps of: performing spectrum sensing on two communication parties, screening out an idle channel and dividing the idle channel into a plurality of sub-channels; writing a central frequency point of a multi-carrier signal communication frequency band into the characteristic parameter set, and establishing a bidirectional communication link by two communication parties based on the characteristic parameter set; the two communication parties carry out variable parameter communication according to the variable parameter duration, in each variable parameter communication, the characteristic parameter set is updated, and the central frequency point of the new multi-carrier signal communication frequency band, the frequency band information of the sub-carrier corresponding to each sub-channel and the configuration information are written in; the two communication parties send and receive a multi-carrier signal containing a pilot frequency sequence based on the characteristic parameter set, and calculate a bit error rate of a subcarrier based on the pilot frequency sequence; and the two communication parties interact bit error rate information, and each subcarrier is configured in combination with the characteristic parameter set, so that variable parameter communication is realized. According to the invention, the reliability of the wireless communication system can be obviously improved.

Description

Technical Field

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

[0002] Based on spectrum sensing technology, the cognitive frequency hopping system organically combines spectrum busy and idle information with frequency hopping communication to realize a dynamic and adaptive transmission scheme. This scheme can effectively avoid external interference by adjusting transmission parameters, thereby improving the reliability of the communication system. However, the traditional cognitive frequency hopping system can only change the frequency point information in the signal characteristic parameters, and cannot adapt to the complex time-varying electromagnetic spectrum environment. At the same time, multi-carrier modulation can decompose the broadband carrier into multiple independent narrowband subcarriers, and each subcarrier can be independently configured with parameters. Therefore, combining multi-carrier modulation with cognitive frequency hopping technology is expected to further improve the robustness of the cognitive frequency hopping system.

[0003] In traditional cognitive systems, spectrum sensing usually uses hard decision methods. When this rough channel sensing method is applied to multi-carrier signals, some subcarriers in the multi-carrier signal will match the occupied channels, resulting in information loss and even communication interruption. In addition, with the rapid growth in the number of users, spectrum resources are becoming increasingly scarce, making it more difficult to find idle communication channels that meet 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 communicating parties is easily interrupted due to interference during variable parameter communication, and the reliability of wireless communication needs to be improved.

[0005] The present invention provides a multi-carrier based autonomous variable parameter communication method, comprising the following steps: The communicating parties perform spectrum sensing, select idle channels as the multi-carrier signal communication frequency band 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 a number of sub-channels; write the center frequency point of the multi-carrier signal communication frequency band into the characteristic parameter set, and the communicating parties establish a two-way communication link based on the characteristic parameter set; The communicating 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 subcarriers corresponding to each subchannel, and the configuration information are written; the communicating parties send and receive multi-carrier signals containing pilot sequences based on the characteristic parameter set, and calculate the bit error rate of the subcarriers corresponding to each subchannel based on the pilot sequence; the communicating parties exchange bit error rate information, configure each subcarrier 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 subcarriers.

[0006] Preferably, the configuration information includes a modulation mode, a transmission power and a usage status of a subcarrier corresponding to a bit error rate of the subcarrier; the usage status includes two states: carrying information and not carrying information.

[0007] Preferably, screening idle channels includes: dividing the available communication frequency band into several channels, the bandwidth of each channel is the same as the bandwidth of the multi-carrier signal, the communicating parties perform spectrum sensing on each channel, sampling and information collection in each channel respectively, obtaining the amplitude matrix corresponding to the sampling information through fast Fourier transform, obtaining the average energy value of each channel according to the amplitude matrix, and selecting the channel with the smallest average energy value as the idle channel.

[0008] 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 subchannel 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 subchannel, is the bandwidth of the multi-carrier signal, is the preset number of subcarriers.

[0009] Preferably, the communicating parties establishing a bidirectional communication link based on the characteristic parameter set includes: The calling party of the communicating parties generates a first characteristic parameter set through spectrum sensing and the second characteristic parameter set , where the first characteristic parameter set Used by the caller to configure the transmission signal; the caller sets the second characteristic parameter set and variable parameter moment Encapsulate into information and send; 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 caller is in the second feature parameter set The corresponding frequency points are matched and received to extract the third characteristic parameter set , the calling party and the answering party successfully establish a two-way communication link.

[0010] Preferably, when the communicating parties perform variable parameter communication according to the variable parameter duration, the variable parameter time Negotiate the communication start time of variable parameters , both parties in communication use variable parameter communication start time As the starting time of variable parameter communication.

[0011] Preferably, calculating the bit error rate of the subcarrier corresponding to each subchannel based on the pilot sequence includes: The communicating parties generate the same pilot sequence and evenly distribute it to each subcarrier according to the preset number of subcarriers; One of the communicating parties sends a multi-carrier signal including a pilot sequence in a channel corresponding to the extracted characteristic parameter set; The other party in the communication compares the received pilot sequence with the known pilot sequence and calculates the bit error rate of the subcarrier corresponding to each subchannel, which is recorded as ,in, is the bit error rate sequence, For the n The bit error rate of the subcarrier corresponding to the subchannel, is the preset number of subcarriers.

[0012] Preferably, the bit error rate information exchanged between the communicating parties includes: the calling party among the communicating 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 bit error rate not of zero as empty carriers, puts the characteristic parameter set into the available carriers, and sends them in a diversity manner to the responding party among the communicating parties; the responding party sends the characteristic parameter set to the calling party in the same manner as described above.

[0013] Preferably, configuring each subcarrier according to the bit error rate information and in combination with a characteristic parameter set includes: The bit error rate of the subcarrier corresponding to each subchannel is compared with the bit error rate threshold; wherein the bit error rate threshold includes a first bit error rate threshold and the second bit error rate threshold ,and Less than ; If the bit error rate of the subcarrier corresponding to a subchannel is greater than or equal to , the subchannel is regarded as an occupied subchannel, and the subcarrier corresponding to the occupied subchannel is set as a null frequency subcarrier that does not send useful information; If the bit error rate of the subcarrier corresponding to a subchannel is less than and greater than or equal to , the subchannel is regarded as a type of idle subchannel, and the subcarriers corresponding to the type of idle subchannel adopt a low-order modulation mode and are allocated a first transmission power; If the bit error rate of the subcarrier corresponding to a subchannel is less than , the subchannel is regarded as a second type of idle subchannel, and the subcarriers corresponding to the second type of idle subchannel adopt a high-order modulation mode and are allocated a second transmission power; 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.

[0014] On the other hand, the present invention provides an autonomous variable parameter communication system based on multi-carrier, comprising: A spectrum sensing module, used to perform spectrum sensing on communication channels, screen out idle channels, divide the idle channels into multiple sub-channels, generate a characteristic parameter set, and update the characteristic parameter set when a parameter change period arrives; A signal transceiver module, used for sending and receiving signals; Signal identification module, used to test Identify and parse feature parameter sets; A channel measurement module is used to obtain the bit error rate of the subcarrier corresponding to each subchannel; A dynamic adjustment module, used for exchanging bit error rate information between communicating parties, and for configuring each subcarrier according to the bit error rate information and in combination with a characteristic parameter set; The multi-carrier based autonomous variable parameter communication system is used to execute the steps in the above multi-carrier based autonomous variable parameter communication method.

[0015] One or more technical solutions provided in the present invention have at least the following technical effects or advantages: When the communicating parties in the present invention establish a two-way communication link stage, the communicating parties perform spectrum sensing, and select idle channels as the multi-carrier signal communication frequency band 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 a plurality of sub-channels, and write the center frequency of the multi-carrier signal communication frequency band into a characteristic parameter set, and the communicating parties establish a two-way communication link based on the characteristic parameter set; when the communicating parties in the present invention enter the autonomous variable parameter communication stage, the communicating parties perform variable parameter communication according to the variable parameter duration, and 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 communicating parties send and receive a multi-carrier signal containing a pilot sequence 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 sequence; the communicating 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. That is, the present invention realizes the node to improve the anti-interference ability of the wireless communication system through spectrum sensing technology and real-time generation and autonomous update of characteristic parameter sets. By introducing bit error rate calculation and signal waveform design, it can avoid narrowband interference in the communication channel, provide multi-carrier signals that fit the electromagnetic environment, increase the flexibility of multi-carrier communication, and improve spectrum utilization. The present invention effectively solves the problem of communication interruption caused by interference of some subcarriers during variable parameter communication between the communicating parties, and can significantly improve the reliability of the wireless communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A specific communication flow chart of a calling party and a responding party in a multi-carrier based autonomous variable parameter communication method provided in Embodiment 1 of the present invention; Figure 2 It is the electromagnetic environment spectrum and signal waveform diagram; among them, Figure 2 (a) is the electromagnetic environment spectrum diagram in the entire communication frequency band. Figure 2 (b) is a multi-carrier signal waveform independently designed after spectrum sensing of the electromagnetic environment using a multi-carrier based autonomous variable parameter communication method provided in Embodiment 1 of the present invention. Figure 2 (c) in the figure is the signal waveform of the designed multi-carrier signal coexisting with the interference signal. DETAILED DESCRIPTION

[0017] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] Embodiment 1: Embodiment 1 provides a multi-carrier based autonomous variable parameter communication method, comprising the following steps: The communicating parties perform spectrum sensing, select idle channels as the multi-carrier signal communication frequency band 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 a number of sub-channels; write the center frequency point of the multi-carrier signal communication frequency band into the characteristic parameter set, and the communicating parties establish a two-way communication link based on the characteristic parameter set; The communicating 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 subcarriers corresponding to each subchannel, and the configuration information are written; the communicating parties send and receive multi-carrier signals containing pilot sequences based on the characteristic parameter set, and calculate the bit error rate of the subcarriers corresponding to each subchannel based on the pilot sequence; the communicating parties exchange bit error rate information, configure each subcarrier 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 subcarriers.

[0019] That is, the present invention mainly includes two stages: the stage in which the communicating parties autonomously establish a two-way communication link and the stage in which the communicating parties conduct autonomous variable parameter communication. Among them, in the stage in which the communicating parties autonomously establish a two-way communication link, it mainly includes: the communicating parties divide the wireless channel into a number of channels and sub-channels; the communicating parties perform spectrum sensing to screen idle channels, and use multi-carrier signals to exchange information to autonomously establish a two-way communication link. In the stage in which the communicating parties conduct autonomous variable parameter communication, it mainly includes: the communicating parties simultaneously enter the autonomous variable parameter communication stage, the communicating parties send and receive multi-carrier signals containing pilot sequences, compare the received pilot sequences with known pilot sequences, and calculate the information bit error rate of each sub-channel; the communicating parties exchange bit error rate information; the communicating parties configure each sub-carrier, design a multi-carrier signal waveform that adapts to the electromagnetic environment, and conduct information exchange.

[0020] Specifically, the configuration information includes a modulation mode, a transmission power and a use status of a subcarrier corresponding to a bit error rate of the subcarrier; the use status includes two states: carrying information and not carrying information.

[0021] Among them, screening idle channels includes: dividing the available communication frequency band into several channels, the bandwidth of each channel is the same as the bandwidth of the multi-carrier signal, the communicating parties perform spectrum sensing on each channel, sampling and information collection in each channel respectively, obtaining the amplitude matrix corresponding to the sampling information through fast Fourier transform, obtaining the average energy value of each channel according to the amplitude matrix, and selecting the channel with the smallest average energy value as the idle channel.

[0022] Specifically, the average energy value is calculated using the following formula:

[0023] In the formula, Indicates The average energy value of the channel is Indicates the number of sampling points, Indicates Channel The amplitude of a time domain sampling point after fast Fourier transform.

[0024] The number of divided subchannels is equal to the number of preset subcarriers. When the multi-carrier signal is orthogonal frequency division multiplexing (OFDM), the number of divided channels is calculated using the following formula: ; The bandwidth of the subchannel 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 subchannel, is the bandwidth of the multi-carrier signal, is the preset number of subcarriers.

[0025] The two communicating parties establish a two-way communication link based on the characteristic parameter set, including: the calling party of the two communicating parties generates a first characteristic parameter set through spectrum sensing. and the second characteristic parameter set , where the first characteristic parameter set Used by the caller to configure the transmission signal; the caller sets the second characteristic parameter set and variable parameter moment The responding party 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 it into a message and send it; the caller is in the second feature parameter set The corresponding frequency points are matched and received to extract the third characteristic parameter set , the calling party and the answering party successfully establish a two-way communication link.

[0026] Among them, when the two communicating parties perform variable parameter communication according to the variable parameter duration, the variable parameter time Negotiate the communication start time of variable parameters , both parties in communication use variable parameter communication start time The caller's signal parameters and the answerer's signal parameters at the start of the variable parameter communication are generated during the link establishment process. The caller receiving signal parameters and the answerer sending signal parameters at the start of the communication are generated during the link establishment process. .

[0027] Specifically, calculating the bit error rate of the subcarriers corresponding to each subchannel based on the pilot sequence includes: the communicating parties generate the same pilot sequence and evenly distribute it to each subcarrier according to the preset number of subcarriers; one of the communicating parties sends a multicarrier signal including the pilot sequence in the channel corresponding to the extracted characteristic parameter set; the other of the communicating parties compares the received pilot sequence with the known pilot sequence, and calculates the bit error rate of the subcarriers corresponding to each subchannel, which is recorded as ,in, is the bit error rate sequence, For the n The bit error rate of the subcarrier corresponding to the subchannel, is the preset number of subcarriers.

[0028] That is, the calling party sends a multi-carrier signal with a pilot sequence in the selected channel, and the answering party compares the received pilot sequence with the known pilot sequence to calculate the information bit error rate of each subchannel; similarly, the answering party sends a multi-carrier signal with a pilot sequence in its selected channel for the calling party to calculate the bit error rate.

[0029] Specifically, the bit error rate information exchanged between the communicating parties includes: the calling party among the communicating 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 bit error rate not of zero as empty carriers, puts the characteristic parameter set into the available carrier by means of diversity, and sends it to the responding party among the communicating parties; similarly, the responding party sends the characteristic parameter set to the calling party in the same manner as above.

[0030] 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 subcarrier corresponding to each subchannel with a bit error rate threshold; wherein the bit error rate threshold includes a first bit error rate threshold and the second bit error rate threshold ,and Less than ; , The size of is affected by the communication distance and the error correction bit information capability of the receiving system. If the bit error rate of the subcarrier corresponding to a subchannel is greater than or equal to , then the subchannel is regarded as an occupied subchannel. This type of channel exceeds the error correction capability of the receiving system and cannot restore the information. The subcarrier corresponding to the occupied subchannel is set as a vacant frequency subcarrier that does not send useful information. If the bit error rate of the subcarrier corresponding to a subchannel is less than and greater than or equal to , then the subchannel is regarded as a type of idle subchannel, and the subcarriers corresponding to the type of idle subchannel adopt low-order modulation and are allocated the first transmission power; that is, low-order modulation is adopted in such subchannels and a higher transmission power is allocated to improve the transmission capacity. If the bit error rate of the subcarrier corresponding to a subchannel is less than , then the subchannel is regarded as a second-class idle subchannel, the communication status of this type of subchannel is good, and the subcarriers corresponding to the second-class idle subchannel adopt a high-order modulation method and are allocated a second transmission power. 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.

[0031] That is, the communicating 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 exchange.

[0032] In the present invention, if the communication is normal, the autonomous variable parameter communication process is repeated, and if the communication is abnormally interrupted, the two-way communication link is reestablished. The communicating parties of the present invention will perform spectrum sensing to update the characteristic parameter set. Specifically, the present invention will obtain the next time slot characteristic parameters in the stage of establishing a two-way communication link and the stage of autonomous variable parameter communication. 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.

[0033] The communication parties perform spectrum sensing to update the characteristic parameter set, which specifically includes: the communication parties autonomously generate the characteristic parameter set of the received signal at the next parameter change time through spectrum sensing. , the other party uses the Update the parameters of the signal sent at the next parameter change time, and update the parameter change time at the same time The communicating parties dynamically adjust the signal parameters based on the signal characteristic parameter set and repeat the above operations. If the communication is abnormally interrupted, the two-way communication link is re-established.

[0034] On the whole, the present invention first divides 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 selects an idle channel through spectrum sensing. Secondly, the caller autonomously establishes a two-way communication link with the responder through a call answering mechanism, and obtains the signal characteristic parameter set for the next time slot. Then, the communicating parties enter the autonomous variable parameter communication stage, calculate the information bit error rate of each sub-channel according to the signal characteristic parameter set, and configure the modulation mode and other parameters of each sub-carrier according to the calculation results, and design a multi-carrier signal waveform adapted to the electromagnetic environment. Finally, the communicating parties perform variable parameter communication according to the designed waveform, and autonomously update the signal characteristic parameter set for the next time slot through spectrum sensing.

[0035] It can also be understood that the idle channels screened out by spectrum sensing in the present invention are 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 channel. The multi-carrier signal has multiple sub-carriers, and each sub-carrier corresponds to a specific frequency band in the selected idle channel as a sub-channel. The present invention first selects an idle channel, and when the spectrum environment is more complex, the selected idle channel is only relatively low in average energy, but it cannot ensure that the energy value is low everywhere in this section of the channel, and there may be narrowband interference. At this time, it is necessary to divide the sub-channels in the channel to find out the unavailable sub-channels in this section of the channel. At this time, the sub-channels correspond to the sub-carriers in the multi-carrier signal. At this time, when judging whether the sub-channel is available, the method of calculating the bit error rate of each sub-channel is adopted. This method can accurately calculate the situation of the sub-channel corresponding to each sub-carrier, and at the same time facilitate the subsequent multi-carrier waveform design.

[0036] The method proposed in the present invention targets complex electromagnetic environments with narrowband interference, updates subcarrier configurations in real time according to channel conditions, implements multi-carrier autonomous variable parameter communication that is resistant to narrowband interference, and effectively improves the spectrum utilization and anti-interference performance of the proposed system.

[0037] Embodiment 2: Embodiment 2 provides a multi-carrier based autonomous variable parameter communication system, including: A spectrum sensing module, used to perform spectrum sensing on communication channels, screen out idle channels, divide the idle channels into multiple sub-channels, generate a characteristic parameter set, and update the characteristic parameter set when a parameter change period arrives; A signal transceiver module, used for sending and receiving signals; Signal identification module, used to test Identify and parse feature parameter sets; A channel measurement module is used to obtain the bit error rate of the subcarrier corresponding to each subchannel; A dynamic adjustment module, used for exchanging bit error rate information between communicating parties, and for configuring each subcarrier according to the bit error rate information and in combination with a characteristic parameter set; The multi-carrier based autonomous variable parameter communication system provided in Example 2 is used to execute the steps in the multi-carrier based autonomous variable parameter communication method described in Example 1.

[0038] The combined working process of each module in the autonomous variable parameter communication system based on multi-carrier is as follows: First, the communicating parties enter the stage of autonomously establishing a two-way communication link, the calling party generates a characteristic parameter set through the spectrum sensing module, and the signal transceiver module sends information and receives it silently. Secondly, the answering party generates a characteristic parameter set through the spectrum sensing module, obtains the calling party characteristic parameter set through the signal transceiver module and the signal discrimination module, and sends the generated characteristic parameter set through the signal transceiver module. After that, the calling party obtains the answering party characteristic parameter set through the signal transceiver module and the signal discrimination module, and the communicating parties successfully establish a two-way communication link. Then, the communicating parties enter the autonomous variable parameter communication stage, send the pilot sequence through the signal transceiver module; use the channel measurement module to calculate the bit error rate of the subchannel, use the signal transceiver module to exchange the bit error rate information, and configure each subcarrier by the dynamic adjustment module to obtain a multi-carrier signal waveform adapted to the electromagnetic environment. Finally, the signal is sent and received through the signal transceiver module and the signal discrimination module. If a useful signal is found in a variable parameter time slot (i.e., communication is normal), the spectrum sensing module is used to generate a characteristic parameter set for the next time slot and return to the variable parameter communication stage to perform variable parameter communication in the next time slot; if no useful signal is found (i.e., communication is abnormally interrupted), the process returns to the stage of establishing a two-way communication link.

[0039] Since the functions of each module in the multi-carrier based autonomous variable parameter communication system provided in Example 2 correspond to the steps in the multi-carrier based autonomous variable parameter communication method provided in Example 1, Example 2 can also be understood by referring to the description of Example 1, which will not be repeated here.

[0040] The autonomous variable parameter communication method based on multi-carrier provided by the present invention is applied to a wireless communication system composed of multiple communication nodes and interference nodes, and is illustrated by combining parameters.

[0041] On the whole, the communication process mainly includes channel division, perception and selection process, user call response and autonomous link establishment process, sub-channel information bit error rate calculation process, waveform design process and autonomous variable parameter communication process.

[0042] After the system is initialized, each node is in a silent receiving state of full-band scanning by default. The caller independently selects the characteristic parameter set according to the real-time status of the wireless spectrum environment. The responder matches the reception by autonomously identifying the characteristic parameter set of the signal through spectrum sensing. The communicating parties autonomously establish a link through the call answering mechanism.

[0043] The communicating parties transfer states, calculate the information bit error rate of the subchannel according to the characteristic parameter set and pilot sequence of the signal, and exchange the results. The communicating parties adjust the power allocation (high or low power), modulation mode (low-order or high-order modulation) and information carrying capacity of the corresponding subcarrier according to the information bit error rate of each subchannel (when different-order modulation modes are used, the total amount of information carried by each subcarrier is different, for example, the number of QPSK bits is twice the number of BPSK bits, and the number of bits for subcarriers that do not send useful information is 0), and design a multi-carrier signal waveform that adapts to the electromagnetic environment. The communicating parties update the signal characteristic parameter set in real time in each variable parameter time slot, and complete autonomous variable parameter communication according to this standard.

[0044] The data fields transmitted by the communicating parties specifically include: Identification (including calling party identification and the responder ID ), variable parameter time , Send data and signal characteristic parameter set . Caller ID and the responder ID Used to verify the identities of both parties in communication; variable parameter time Used to negotiate the starting time of variable parameter communication between the two parties; send data Indicates the information content to be transmitted by both parties; signal characteristic parameter set It is used to coordinate the parameter configuration of both communicating parties, including the center frequency of the multi-carrier signal, subcarrier bit error rate information, modulation mode, and usage status, and uniformly encapsulate the above characteristic parameters.

[0045] For example, a wireless communication system consisting of a sending node, a receiving node and three interference nodes is built by using software radio equipment USRP-2920 and LabVIEW software. This system is completely distributed, that is, the system consists of a series of communication nodes that can be moved arbitrarily, the nodes are dynamic and arbitrarily distributed, there is no control center and public control channel in the system, all nodes have equal status, no other preset network facilities are required, and autonomous links can be established and autonomous variable parameter communication can be carried out at any time and any place. The system consists of: communication nodes (USRP-A is the responder and USRP-B is the caller), each of which has the ability to send and receive information. USRP-C, USRP-D, and USRP-E are interference nodes, which send narrowband interference 1, narrowband interference 2, and narrowband interference 3 with different gain sizes in three different frequency bands. The distance between the two communicating parties is 50 cm, and the three interference sources are placed around them at a distance of 25 cm from the two communicating parties, that is, the five devices from left to right are narrowband interference 3, communication node, narrowband interference 2, communication node, and narrowband interference 1.

[0046] For details, see Figure 1 , the communication steps include: Step 1: System initialization: After the system is started, it enters the initialization state. By default, all communication nodes are in the silent frequency scanning receiving state after startup. In this state, the system The frequency band is divided and sensed based on the bandwidth of the multi-carrier signal of 5MHz and the preset number of sub-carriers of 64, the energy value of each channel is calculated, the idle channels and occupied channels are recorded, and if the information of a legitimate user is detected in the occupied channel or a call needs to be initiated, the information sending state is entered.

[0047] 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, the communication node becomes the caller. Set to 100, Set to 200. The caller sets Perform spectrum sensing within the frequency band and generate characteristic parameter sets and .in, Used by the caller to configure the sending signal and set the characteristic parameter Encapsulated into the sending information for the responder to configure the sending signal, and encapsulate the variable parameter time according to user needs To ensure that both parties enter the variable parameter communication stage at the same time. Finally, the caller enters the frequency sweep reception state and Real-time detection and reception at the corresponding frequency point.

[0048] Step 3, user matching response: When the user detects the legitimate user's information in the silent scanning reception state and then switches to the information sending state, this communication node acts as the responder. Set to 200, Set to 100. The answering party autonomously identifies the characteristic parameter set of the signal sent by the calling party , after matching and receiving, parse the received information and extract the other party With one's own If the match is successful, the remaining data is parsed. As the characteristic parameter set of the signal sent by the responder, the system is set Spectrum sensing in the frequency band range and autonomous generation of feature parameter sets , As the characteristic parameter set of the answering party receiving signal and the characteristic parameter set of the calling party sending signal in the next time slot. After this, the characteristic parameter set is encapsulated And send the message.

[0049] Step 4: Synchronous transfer of communication status: The caller sets the characteristic parameter After matching and receiving the corresponding frequency points, extract After that, the caller enters the waiting state and enters the variable parameter communication phase synchronously with the answerer.

[0050] At this point, it indicates that the calling party and the answering party have successfully established a two-way communication link. Then, both parties synchronously enter the autonomous variable parameter communication stage, in which variable parameter communication is performed according to the variable parameter duration preset by the user and the status of both parties is equal, and the operations performed are also the same.

[0051] Step 5: Calculate the information bit error rate of the channel: Both parties generate the same pilot sequence group and evenly distribute it to 64 subcarriers. The caller transmitter calculates the bit error rate of the channel according to the characteristic parameter set. Send a multi-carrier signal. After receiving it, the receiver of the responding party compares the pilot sequence in each sub-carrier and calculates the information bit error rate of each sub-carrier. Similarly, the answering party transmitter and the calling party receiver are based on the characteristic parameter set. Calculate the information bit error rate of the channel.

[0052] Step 6: Exchange bit error rate information: Both parties in communication update the characteristic parameter set autonomously, then set the number of subcarriers to 4, set the carrier with zero bit error rate as an available carrier, and finally use diversity to set the characteristic parameter set The receiver separates the information in each subcarrier and finds the information bit error rate sequence of the channel.

[0053] Step 7: Subcarrier configuration: Both parties in communication configure the subcarriers according to the bit error rate threshold sequence. Each sub-carrier is classified. A sub-channel with a bit error rate greater than 0.1 is considered an occupied sub-channel, and the sub-carrier corresponding to such a sub-channel is set to a blank frequency; a sub-channel with a bit error rate greater than 0 and less than 0.1 is considered a type I idle sub-channel, and the transmission power of the carrier corresponding to such a sub-channel is increased by 1 times, and the modulation mode is set to BPSK; a sub-channel with a bit error rate equal to 0 is considered a type II idle sub-channel, and a large amount of information is transmitted through the carrier corresponding to such a sub-channel, and the modulation mode is set to QPSK. Afterwards, the communicating parties allocate information to each sub-carrier for sending and receiving according to the above strategy.

[0054] Step 8: Autonomously update the characteristic parameter set: Perform spectrum sensing every parameter change period T, and autonomously generate the characteristic parameter set 583MHz for the next parameter change time according to the sensing result, which is used to configure the received signal and write The other party is informed that the other party adopts the characteristic parameter set to configure the sending signal, and then proceeds to step 5 for variable parameter communication in the next time slot until the user actively stops communicating.

[0055] The calling party and the answering party communicate using the above-mentioned communication method.

[0056] In addition, in the present invention, the multi-carrier signal uses orthogonal frequency division multiplexing, i.e., OFDM signal, and sets the number of OFDM subcarriers, system bandwidth, and modulation mode, see Table 1. At the same time, the transmission frequency point, modulation mode, waveform, IQ sampling rate, and transmission gain of the narrowband interference are set. The electromagnetic environment of the communication frequency band and the waveform of the multi-carrier signal of the two communicating parties are obtained by a spectrum analyzer, such as Figure 2 The method provided by the present invention was compared with the same type of method (a multi-carrier frequency hopping system that only changes the communication center frequency) and the test process was carried out 3000 times, with 448 bits of information being sent and received each time. Specifically, Figure 2 (a) in the figure is the electromagnetic environment spectrum diagram in the entire communication frequency band. As shown in the figure, there are three narrowband interferences. The specific parameters are shown in Table 2. Figure 2 (b) in the figure is a 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, some subcarriers affected by interference are set to empty frequencies, which are specifically manifested as signal depressions. Such subcarriers do not carry any useful information. Figure 2 (c) in the figure is the signal waveform of the designed multi-carrier signal coexisting with the interference signal. It can be seen that when the multi-carrier signal coexists with the narrowband interference signal, the multi-carrier variable parameter communication can be completed by adjusting the multi-carrier signal parameters. The specific results are shown in Table 1, Table 2 and Table 3.

[0057] Table 1 OFDM signal configuration

[0058] Table 2 Narrowband interference signal configuration

[0059] Table 3 Performance comparison between the multi-carrier based autonomous variable parameter communication system provided by the present invention and the traditional multi-carrier frequency hopping system

[0060] From the results in Table 3, it can be seen that the bit error rate of the present invention is significantly reduced. Compared with the traditional multi-carrier autonomous variable parameter communication system, the multi-carrier autonomous variable parameter communication system proposed in the present invention has obvious advantages and enhances the transmission reliability of communication.

[0061] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A multi-carrier based autonomous variable parameter communication method, characterized in that: The following steps are involved: The communicating parties perform spectrum sensing, select idle channels as the multi-carrier signal communication frequency band 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 a number of sub-channels; write the center frequency point of the multi-carrier signal communication frequency band into the characteristic parameter set, and the communicating parties establish a two-way communication link based on the characteristic parameter set; The communicating 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 subcarriers corresponding to each subchannel, and the configuration information are written; the communicating parties send and receive multi-carrier signals containing pilot sequences based on the characteristic parameter set, and calculate the bit error rate of the subcarriers corresponding to each subchannel based on the pilot sequence; the communicating parties exchange bit error rate information, configure each subcarrier 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 subcarriers.

2. The autonomous variable parameter communication method based on multi-carrier according to claim 1, characterized in that: The configuration information includes the modulation mode, transmission power and use status of the subcarrier corresponding to the bit error rate of the subcarrier; the use status includes two states: carrying information and not carrying information.

3. The autonomous variable parameter communication method based on multi-carrier according to claim 1, characterized in that: Screening idle channels includes: dividing the available communication frequency band into several channels, the bandwidth of each channel is the same as the bandwidth of the multi-carrier signal, the communicating parties perform spectrum sensing on each channel, sampling and information collection in each channel respectively, obtaining the amplitude matrix corresponding to the sampled information through fast Fourier transform, obtaining the average energy value of each channel according to the amplitude matrix, and selecting the channel with the smallest average energy value as the idle channel.

4. The autonomous variable parameter communication method based on multi-carrier according to claim 3, characterized in that: 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 subchannel 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 subchannel, is the bandwidth of the multi-carrier signal, is the preset number of subcarriers.

5. The autonomous variable parameter communication method based on multi-carrier according to claim 1, characterized in that: The two communicating parties establish a two-way communication link based on the characteristic parameter set, including: The calling party of the communicating parties generates a first characteristic parameter set through spectrum sensing and the second characteristic parameter set , where the first characteristic parameter set Used by the caller to configure the transmission signal; the caller sets the second characteristic parameter set and variable parameter moment Encapsulate into information and send; 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 caller is in the second feature parameter set The corresponding frequency points are matched and received to extract the third characteristic parameter set , the calling party and the answering party successfully establish a two-way communication link.

6. The autonomous variable parameter communication method based on multi-carrier according to claim 5, characterized in that: When the two communicating parties perform variable parameter communication according to the variable parameter duration, the variable parameter time Negotiate the communication start time of variable parameters , both parties in communication use the variable parameter communication start time As the starting time of variable parameter communication.

7. The autonomous variable parameter communication method based on multi-carrier according to claim 1, characterized in that: Calculating the bit error rate of the subcarrier corresponding to each subchannel based on the pilot sequence includes: The communicating parties generate the same pilot sequence and evenly distribute it to each subcarrier according to the preset number of subcarriers; One of the communicating parties sends a multi-carrier signal including a pilot sequence in a channel corresponding to the extracted characteristic parameter set; The other party in the communication compares the received pilot sequence with the known pilot sequence and calculates the bit error rate of the subcarrier corresponding to each subchannel, which is recorded as ,in, is the bit error rate sequence, For the n The bit error rate of the subcarrier corresponding to the subchannel, is the preset number of subcarriers.

8. The autonomous variable parameter communication method based on multi-carrier according to claim 1, characterized in that: The bit error rate information exchanged between the communicating parties includes: the calling party among the communicating 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 bit error rate not zero as empty carriers, puts the characteristic parameter set into the available carriers, and sends them in a diversity manner to the responding party among the communicating parties; the responding party sends the characteristic parameter set to the calling party in the same manner as above.

9. The autonomous variable parameter communication method based on multi-carrier according to claim 2, characterized in that: Configuring each subcarrier according to the bit error rate information and in combination with the characteristic parameter set includes: The bit error rate of the subcarrier corresponding to each subchannel is compared with the bit error rate threshold; wherein the bit error rate threshold includes a first bit error rate threshold and the second bit error rate threshold ,and Less than ; If the bit error rate of the subcarrier corresponding to a subchannel is greater than or equal to , the subchannel is regarded as an occupied subchannel, and the subcarrier corresponding to the occupied subchannel is set as a null frequency subcarrier that does not send useful information; If the bit error rate of the subcarrier corresponding to a subchannel is less than and greater than or equal to , the subchannel is regarded as a type of idle subchannel, and the subcarriers corresponding to the type of idle subchannel adopt a low-order modulation mode and are allocated a first transmission power; If the bit error rate of the subcarrier corresponding to a subchannel is less than , the subchannel is regarded as a second type of idle subchannel, and the subcarriers corresponding to the second type of idle subchannel adopt a high-order modulation mode and are allocated a second transmission power; 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.

10. An autonomous variable parameter communication system based on multi-carrier, characterized in that: include: A spectrum sensing module, used to perform spectrum sensing on communication channels, screen out idle channels, divide the idle channels into multiple sub-channels, generate a characteristic parameter set, and update the characteristic parameter set when a parameter change period arrives; A signal transceiver module, used for sending and receiving signals; Signal identification module, used to test Identify and parse feature parameter sets; A channel measurement module is used to obtain the bit error rate of the subcarrier corresponding to each subchannel; A dynamic adjustment module, used for exchanging bit error rate information between communicating parties, and for configuring each subcarrier according to the bit error rate information and in combination with a characteristic 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 as described in any one of claims 1-9.

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