A subcarrier-based intelligent waveform identification technology, and an FPGA implementation method and device

Abstract

The application discloses a kind of based on subcarrier's intelligent waveform identification technology and FPGA implementation method and device.This application, physical layer transmitting end keeps radio frequency parameter unchanged when bandwidth switches, only realizes waveform bandwidth change by adjusting the allocation number of effective subcarrier in OFDM symbol;Physical layer receiving end identifies bandwidth by waveform pilot information and carries out demodulation;Physical layer calculates the error vector magnitude value of each subcarrier and reports MAC layer, and MAC layer combines the error vector magnitude value of data message and probe message, judges available continuous frequency band bandwidth, and decides whether to switch waveform bandwidth and switching mode.The application can complete bandwidth switching without reconfiguring radio frequency, avoid communication interruption, switching time reaches microsecond level, and is suitable for adaptive bandwidth adjustment of wireless self-organizing network OFDM communication system.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a subcarrier-based intelligent waveform recognition technology and its FPGA implementation method and apparatus, applicable to adaptive bandwidth adjustment in wireless ad hoc OFDM communication systems. Background Technology

[0002] As the application of wireless ad hoc networks becomes more widespread, various industries are placing increasingly higher demands on their performance. They want ad hoc networks to have high-speed data transmission capabilities while also ensuring the reliability of wireless communication over long distances. Furthermore, with limited spectrum resources, signals are highly susceptible to channel interference during wireless communication, leading to problems such as bit errors and frame loss.

[0003] Although there are corresponding technical solutions for each problem, it is difficult to achieve a complete solution. For example, in long-distance communication, broadband waveforms have poor reliability under the same transmission power conditions, and the system can only choose narrowband waveforms for communication. However, the transmission rate of narrowband waveforms is much lower than that of broadband waveforms in short-distance communication. This undoubtedly fails to give full play to the advantages of the system. Therefore, how to balance the relationship between throughput and reliability has become a major problem that must be overcome in practical applications.

[0004] In addition, in-band co-channel or adjacent-channel interference is a major challenge for the reliability of wireless transmission in self-organizing networks. Although frequency hopping or frequency selection techniques can be used to temporarily avoid interference sources, the range of available frequency bands becomes even more limited when the already limited spectrum resources are further restricted by external hardware devices such as power amplifiers and antennas. When broadband waveforms cannot be used to transmit signals due to a lot of in-band interference, narrowband waveforms must be used to avoid interference signals in order to ensure the stability of the self-organizing network.

[0005] Cisco was the first company to conduct systematic research on adaptive bandwidth technology. They modified parameters such as the radio frequency clock frequency on 802.11 protocol-related equipment to configure channel waveforms with bandwidths of 5MHz, 10MHz, and 20MHz, and dynamically allocated them to each node according to the channel environment. However, existing methods involve a process of reconfiguring radio frequency parameters during bandwidth switching, which can lead to power outages and restarts of communication nodes, causing network communication interruptions and affecting system stability. Summary of the Invention

[0006] This invention addresses the problems in the prior art by providing a subcarrier-based intelligent waveform recognition technology and its FPGA implementation method and apparatus. It aims to solve the technical problem that existing adaptive bandwidth technology requires reconfiguration of radio frequency parameters during switching, which leads to communication interruption. At the same time, it also solves the trade-off between transmission rate, transmission distance and anti-interference capability in ad hoc network communication.

[0007] This invention is based on the design of ad hoc networks and proposes an intelligent waveform recognition method based on subcarriers. This method is applied to a wireless ad hoc network OFDM communication system, where each node includes a MAC layer, a physical layer transmitter, and a physical layer receiver. The method includes the following steps: Step 1: Before networking, each node in the self-organizing network uses a unified default bandwidth waveform to transmit control messages to complete the networking. After networking, waveform bandwidth is allocated for communication between nodes. Step 2: The physical layer transmitter determines the number of effective subcarriers of the OFDM symbol used to carry data based on the currently allocated waveform bandwidth, and performs OFDM modulation on the data message according to the determined number of effective subcarriers and transmits it; when the waveform bandwidth changes, the physical layer transmitter performs a bandwidth switching operation. During the bandwidth switching process, the radio frequency clock frequency, radio frequency local oscillator frequency and radio frequency sampling rate of the physical layer transmitter remain unchanged, and the change in waveform bandwidth is only achieved by adjusting the number of effective subcarriers allocated within the OFDM symbol; Step 3: The physical layer receiver autonomously identifies the waveform bandwidth used by the current physical layer transmitter based on the preamble information of the waveform in the received signal, without the MAC layer needing to inform it of the baseband processing parameters in advance. Based on the identified waveform bandwidth, the receiver performs OFDM demodulation and subsequent baseband processing on the received signal, wherein OFDM demodulation yields frequency domain OFDM symbols. Step 4: The physical layer receiver calculates the error vector amplitude value of each subcarrier of the frequency domain OFDM symbol obtained after OFDM demodulation in step 3, and calculates the error vector amplitude value of each subcarrier of the data message. The calculated error vector amplitude value of each subcarrier of the data message is used as the signal quality assessment result and reported to the MAC layer along with the data message recovered by demodulation in step 3. The magnitude of the error vector amplitude value is inversely proportional to the signal quality on the corresponding subcarrier. Step 5: During idle time slots between nodes in the ad hoc network, the MAC layer controls the physical layer transmitter to send probe messages to other nodes in the ad hoc network. The probe messages are used to detect the signal quality of other frequency points outside the current operating frequency band. The MAC layer receives the error vector amplitude values ​​of each frequency point from the probe messages fed back by the physical layer. Step 6: The MAC layer comprehensively judges the bandwidth corresponding to the available continuous frequency band that meets the communication threshold based on the error vector amplitude values ​​of each subcarrier of the data message and the error vector amplitude values ​​of each frequency point of the probe message. Based on the comparison result between the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth, it decides whether to switch the waveform bandwidth in the next scheduling cycle and to which waveform bandwidth to switch to, generates a bandwidth switching decision, and sends it to the physical layer for execution.

[0008] Further, in step 6, the MAC layer determines whether to switch the waveform bandwidth and to which waveform bandwidth to switch in the next scheduling cycle based on the comparison result between the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth. Specifically, this includes: The error vector amplitude value of each frequency point is compared with the preset communication threshold. The frequency points that meet the communication threshold are divided into continuous frequency bands, and the bandwidth value of each continuous frequency band is calculated. If there exists a continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then the bandwidth increment condition is met. In the next scheduling cycle, the waveform bandwidth of the data message will be increased by a step value based on the current bandwidth, where the step value is 10% of the current data message waveform bandwidth. If there is no continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then record the maximum bandwidth value of the continuous frequency points within the available frequency band that meets the communication threshold, and adjust the waveform bandwidth of the data message to 80% of this maximum bandwidth value in the next scheduling cycle.

[0009] Furthermore, in step 2, before the physical layer transmitter performs OFDM modulation on the data message according to the determined number of effective subcarriers, a subcarrier power adjustment step is also included: The physical layer transmitter configures the power coefficient of each effective subcarrier under different bandwidths independently. During OFDM modulation, it allocates the corresponding transmit power to each effective subcarrier under different bandwidths so that the total RF output power under different waveform bandwidths remains consistent.

[0010] Furthermore, in step 4, the physical layer receiver reports the error vector amplitude value of each subcarrier to the MAC layer as a signal quality assessment parameter, without calculating the signal-to-noise ratio separately; the physical layer receiver only performs fixed-point arithmetic on the error vector amplitude value in the baseband processing, without performing floating-point arithmetic on the signal-to-noise ratio involving division or logarithms, so as to reduce FPGA resource consumption and computational complexity.

[0011] Further, in step 3, the physical layer receiver autonomously identifies the waveform bandwidth used by the current physical layer transmitter based on the preamble information of the received signal, specifically including: The synchronization module of the physical layer receiver performs preamble detection on the received signal, extracts bandwidth identification features from the preamble information of the waveform in the signal, matches the extracted bandwidth identification features with the preset preamble features of various bandwidth waveforms supported by the system, determines the waveform bandwidth used by the current physical layer transmitter based on the matching result, and configures OFDM demodulation parameters according to the waveform bandwidth.

[0012] Furthermore, in step 1, the default bandwidth waveform used by each node before networking is the narrowband waveform with the highest reliability among the various bandwidth waveforms supported by the system.

[0013] Further, in step 5, the MAC layer controls the physical layer transmitter to send probe messages to other nodes in the ad hoc network during idle time slots between nodes within the ad hoc network. Specifically, this includes: According to the agreement between neighboring nodes, the nodes in the network coordinate the time when each node sends probe messages to other nodes, so that each node sends probe messages in turn during idle time slots that do not conflict with each other. The probe messages use the maximum bandwidth waveform supported by the system and are sent periodically in preset frequency steps in other available frequency bands outside the current operating frequency band until all frequency bands supported by the system are covered.

[0014] A subcarrier-based intelligent waveform recognition FPGA implementation device is applied to a wireless ad hoc OFDM communication system. Each node of the wireless ad hoc OFDM communication system includes a MAC layer processing module, a physical layer transmitting module, and a physical layer receiving module, comprising: The MAC layer processing module is used to allocate waveform bandwidth to each node when the network is established; to receive the error vector amplitude values ​​of each subcarrier reported by the physical layer during communication, and to control the physical layer transmission module to send probe messages to other nodes in the ad hoc network in idle time slots to detect the signal quality of other frequency points outside the current operating frequency band; and to comprehensively determine the bandwidth corresponding to the available continuous frequency band that meets the communication threshold based on the error vector amplitude values ​​of the data message and the probe message, and to generate a bandwidth switching decision based on the comparison result between the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth and send it to the physical layer. The physical layer transmission module receives bandwidth switching decisions and data messages to be transmitted from the MAC layer processing module. It determines the number of effective subcarriers for the OFDM symbols used to carry the data based on the allocated waveform bandwidth, performs OFDM modulation on the data messages according to the determined number of effective subcarriers, and frames and transmits them. The physical layer transmission module maintains the RF clock frequency, RF local oscillator frequency, and RF sampling rate constant when the waveform bandwidth changes, and achieves the change in waveform bandwidth by adjusting the number of effective subcarriers allocated within the OFDM symbol. The physical layer receiving module is used to autonomously identify the waveform bandwidth used by the current physical layer transmitting module based on the preamble information of the waveform in the received signal, without requiring the MAC layer processing module to inform it of the baseband processing parameters in advance. Based on the identified waveform bandwidth, it performs OFDM demodulation and subsequent baseband processing on the received signal. The subsequent baseband processing includes channel estimation, equalization, and demapping, wherein OFDM demodulation yields frequency-domain OFDM symbols. The physical layer receiving module is also used to calculate the error vector amplitude value of each subcarrier of the frequency-domain OFDM symbols obtained after OFDM demodulation, calculate the error vector amplitude value of each subcarrier of the data message, and report the calculated error vector amplitude values ​​of each subcarrier of the data message as a signal quality assessment result along with the demodulated and recovered data message to the MAC layer processing module. The radio frequency interface module is used to connect to the radio frequency unit and realize the conversion and transmission and reception between baseband signals and radio frequency signals.

[0015] Furthermore, the MAC layer processing module generates a bandwidth switching decision based on a comparison between the bandwidth corresponding to the available continuous frequency band and the bandwidth of the current waveform, specifically for executing the following logical judgments: The error vector amplitude value of each frequency point is compared with the preset communication threshold. The frequency points that meet the communication threshold are divided into continuous frequency bands, and the bandwidth value of each continuous frequency band is calculated. If there exists a continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then a decision is generated to increase the data message waveform bandwidth by 10% of the current bandwidth in the next scheduling cycle. If there is no continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then record the maximum bandwidth value that is continuous within the available frequency band and meets the communication threshold, and generate a decision to adjust the data message waveform bandwidth to 80% of this maximum bandwidth value in the next scheduling cycle.

[0016] Furthermore, before performing OFDM modulation on the data message according to the determined number of effective subcarriers, the physical layer transmission module is also used to configure the power coefficients of the effective subcarriers under different bandwidths independently, and allocate the corresponding transmission power to each effective subcarrier under different bandwidths during OFDM modulation, so that the total RF output power under different waveform bandwidths remains consistent.

[0017] The beneficial effects of this invention are: In this invention, the physical layer is designed based on OFDM. During waveform bandwidth switching, there is no need to change the RF configuration; the effect of changing the waveform bandwidth can be achieved simply by adjusting the subcarrier allocation method within the OFDM symbol in the physical layer. Furthermore, different powers are allocated to subcarriers with different bandwidths during OFDM modulation, ensuring that the total RF output power of waveforms with different bandwidths is the same. This satisfies the communication distance requirements without increasing energy consumption. Simultaneously, the waveform bandwidth switching time can reach the microsecond level, exhibiting extremely high real-time performance.

[0018] In addition, the physical layer can accurately determine the location of interference frequency points in the channel by calculating the subcarrier signal quality after the signal passes through the wireless channel. Through the feedback mechanism between the physical layer and the MAC layer, the results are fed back to the MAC layer in real time. The MAC layer periodically adjusts the bandwidth waveform used between nodes according to the subcarrier signal quality to meet the communication needs under different channel environments.

[0019] In summary, this invention can simultaneously address the core requirements of wireless transmission, such as in-band interference resistance, long-distance transmission, and high-speed communication. Therefore, research on the content of this patent is of great significance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the physical layer system model of the present invention, showing the data processing flow of the physical layer transmitter (randomization → LDPC encoding → QAM mapping → OFDM modulation → frame transmission) and the data processing flow of the physical layer receiver (synchronization → OFDM demodulation → channel estimation → equalization and phase tracking → QAM demapping → LDPC decoding → derandomization). Figure 2 This is a flowchart of the decision-making process of the MAC layer in the intelligent waveform recognition technology of the present invention, which shows the complete process of the MAC layer making bandwidth adjustment decisions based on the feedback results of the error vector amplitude values ​​of data messages and probe messages; Figure 3 This is a schematic diagram of the physical layer synchronization and bandwidth identification principle of the present invention, showing the composition structure of ZC sequence and irrelevant sequence in short preamble, and the comparison relationship of correlation peak shift under different bandwidths; Figure 4 This is a schematic diagram of the bandwidth identification principle of the synchronization module of the present invention; Figure 5 This is a comparison chart of the test results of communication rates and transmission distances for different bandwidth waveforms according to the present invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings. Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The directional terms such as left, center, right, top, and bottom in the embodiments of the present invention are only relative concepts or referenced to the normal use state of the product, and should not be considered restrictive.

[0022] This ad hoc network system mainly consists of two parts: physical layer data processing and MAC layer network scheduling. The MAC layer is mainly responsible for network maintenance and resource allocation, while the physical layer is mainly responsible for baseband data processing.

[0023] The physical layer uses OFDM technology, and data processing follows the following... Figure 1 The process is as follows: After receiving the data message from the MAC layer, the data message is first randomized, LDPC encoded, and QAM mapped. The mapped frequency domain data symbols are then allocated to each effective subcarrier of the OFDM symbol. An IFFT operation is performed on the frequency domain OFDM symbol to convert it to the time domain. A cyclic prefix is ​​added before the time domain OFDM symbol as a guard interval. Finally, the symbol is framed with the preamble data and sent to the radio frequency for transmission. After the signal is synchronized at the receiving end, the signal is demodulated using OFDM (including removing the cyclic prefix and performing an FFT operation) to obtain the frequency domain data. Then, channel estimation is performed on the signal. After equalization and phase tracking, QAM demapping is performed. Finally, LDPC decoding and derandomization are performed. Finally, the data message is uploaded to the MAC layer to complete the data transmission between nodes.

[0024] When the MAC layer sends data messages to the physical layer, it can add an interface message to the data frame header to inform the physical layer transmitter in advance of information such as the waveform bandwidth, frequency, modulation scheme, and coding rate used in this data frame. The physical layer transmitter can then process the data according to the relevant configuration. The physical layer receiver has an automatic waveform recognition function and can autonomously parse the data information without requiring the MAC layer to provide baseband processing parameters in advance. After completing data processing, the physical layer receiver uploads the data message to the MAC layer. Before uploading the data message frame header, the physical layer receiver will carry the error vector amplitude values ​​of each subcarrier in this data frame. The MAC layer will periodically adjust the channel parameters of each node in the network based on the received feedback results, such as whether there is interference at the frequency point or whether the waveform bandwidth needs adjustment.

[0025] The following combination Figures 1 to 4 The specific embodiments of the present invention will be described in detail below.

[0026] Step 1: Network Establishment and Initial Waveform Bandwidth Allocation Before networking, each node in the self-organizing network uses a unified default bandwidth waveform to transmit control messages to complete the networking process. After networking, waveform bandwidth is allocated for communication between nodes. The default bandwidth waveform used by each node before networking is the narrowband waveform with the highest reliability among the various bandwidth waveforms supported by the system.

[0027] Before network establishment, isolated nodes locate other nodes by sending control messages. A high-reliability bandwidth waveform is typically chosen for information transmission. This waveform selection must meet the data transmission requirements for maintaining network scale, ensure sufficient margin for long-distance point-to-point transmission, and possess anti-interference capabilities to guarantee normal communication within the network. Considering that there are no large-volume data services during the network setup phase, a high-reliability narrowband waveform is selected to transmit control messages to minimize the impact of channel interference.

[0028] Step 2: Physical Layer Transmitter Processing and Bandwidth Switching The bandwidth switching method designed in this invention does not require changes to the radio frequency configuration; it achieves the effect of changing the bandwidth by altering the allocation of subcarriers within the OFDM symbol. After determining the OFDM waveform sampling rate and subcarrier spacing, the total number of subcarriers in the OFDM modulation can be determined. Subcarriers include data subcarriers, guard subcarriers, and pilot subcarriers. The number of each type of subcarrier differs in OFDM symbols with different bandwidths, but the total number of subcarriers remains constant.

[0029] First, the total number of subcarriers within an OFDM symbol is determined based on the maximum bandwidth supported by the system. When the bandwidth decreases, some data subcarriers and pilot subcarriers within the maximum bandwidth are used as guard subcarriers, and the remaining effective data subcarriers and pilot subcarriers are continuous in the frequency domain. The ratio of the number of data subcarriers under different bandwidths is basically equal to the ratio between bandwidths.

[0030] The physical layer transmitter configures independent power coefficients for effective subcarriers under different bandwidths. During OFDM modulation, corresponding transmit power is allocated to each effective subcarrier under different bandwidths to maintain a consistent total RF output power across different waveform bandwidths. The baseband signal output power matches the maximum bandwidth supported by the system. Therefore, when the waveform switches to a narrower bandwidth, more data subcarriers are treated as guard subcarriers, requiring adjustment of the actual data subcarrier power. The power increase factor is approximately equal to the ratio between bandwidths; for example, the data subcarrier power for a 20MHz bandwidth waveform is half that of a 10MHz bandwidth waveform, but the total transmit power remains consistent across both bandwidths. Using this method, narrowband waveforms can carry more energy on their effective subcarriers, enabling them to transmit over longer distances.

[0031] The physical layer transmitter determines the number of effective subcarriers of OFDM symbols used to carry data based on the currently allocated waveform bandwidth, and performs OFDM modulation on the data message according to the determined number of effective subcarriers and then transmits it.

[0032] The "number of effective subcarriers in an OFDM symbol" refers to the number of subcarriers actually used to carry data messages out of the total number of subcarriers contained in an OFDM symbol. The number of effective subcarriers varies depending on the currently allocated waveform bandwidth—the wider the waveform bandwidth, the more effective subcarriers; the narrower the waveform bandwidth, the fewer effective subcarriers. In an OFDM system, the relationship between waveform bandwidth and the number of effective subcarriers is determined by the subcarrier spacing. When the subcarrier spacing is fixed, the waveform bandwidth is directly proportional to the number of effective subcarriers. Therefore, the waveform bandwidth can be changed simply by adjusting the allocated number of effective subcarriers, without any adjustments required at the radio frequency end.

[0033] When the waveform bandwidth changes, the physical layer transmitter performs a bandwidth switching operation. During the bandwidth switching process, the RF clock frequency, RF local oscillator frequency and RF sampling rate of the physical layer transmitter remain unchanged. The change in waveform bandwidth is achieved only by adjusting the number of effective subcarriers allocated within the OFDM symbol.

[0034] Step 3: Waveform identification and demodulation at the physical layer receiver The synchronization module at the physical layer receiver performs preamble detection on the received signal, extracts bandwidth identification features from the preamble information of the waveform in the signal, matches the extracted bandwidth identification features with preset preamble features of various bandwidth waveforms supported by the system, and determines the waveform bandwidth used by the current physical layer transmitter based on the matching result. This does not require the MAC layer to inform the baseband processing parameters in advance. Based on the identified waveform bandwidth, the received signal is demodulated using OFDM and subsequent baseband processing is performed. The subsequent baseband processing includes channel estimation, equalization, and demapping, where OFDM demodulation yields frequency domain OFDM symbols.

[0035] The specific implementation of the "preamble detection" is as follows: During framing, the physical layer transmitter adds a short preamble for synchronization and a long preamble for channel estimation before the data symbols. After OFDM modulation, the signal enters the framing module. Before the time-domain signal is sent for radio frequency transmission, a short preamble for synchronization and a long preamble for channel estimation are added before the data symbols. After framing, the signal includes one short preamble symbol, one long preamble, and several data symbols. The short preamble consists of two sets of identical ZC sequences, each set of sequences being half the length of an OFDM symbol.

[0036] To achieve waveform bandwidth identification, the present invention employs the following method, such as... Figure 4 As shown: 1) The short preamble of the transmitting end framing module is differentiated by inserting a sequence unrelated to the local sequence between the two sequences within the short preamble. This sequence is called the "irrelevant sequence," and its length is related to the bandwidth. No irrelevant sequence is inserted when using the maximum waveform bandwidth. When the waveform needs to switch to a narrower bandwidth, for every reduction of the bandwidth by i (MHz), the length of the irrelevant sequence inserted between the two sequences in the short preamble increases by N. The value of i corresponds to the bandwidth switching step supported by the system, and the value of N must satisfy the condition that the correlated peak value after shifting and superposition can be clearly distinguished by the peak detection circuit at the receiving end in different bandwidth modes. For example, if the system supports four bandwidth modes: 40MHz, 20MHz, 10MHz, and 5MHz, we can set i=5MHz and N=16, with irrelevant sequence lengths N corresponding to the four bandwidths being 0, 64, 96, and 112, respectively.

[0037] 2) When a data frame is received, the synchronization module at the physical layer receiver has a local sequence that is strongly correlated with the ZC sequence of the short preamble. Upon detecting the arrival of a data frame, the local sequence and the received data undergo a point-by-point sliding correlation operation. When the short preamble and the local sequence completely overlap within the sliding window, the correlation calculation result exceeds a preset threshold, indicating a valid preamble has been detected. The position of the correlation peak is recorded to obtain symbol timing synchronization. Since the short preamble contains two identical synchronization sequences, a data frame will generate two correlation peaks exceeding the threshold. By shifting and superimposing the correlation peak calculation results, the superposition of the two sets of correlation peaks produces a maximum peak, which is used to accurately determine the starting position of the long preamble and data symbols. Figure 3 As shown.

[0038] 3) To achieve waveform bandwidth identification, when the receiver calculates the correlation of short preambles with different bandwidths, the first set of short preamble sequences for different bandwidths are in the same position, so the position of the first correlation peak is consistent. However, since the lengths of the irrelevant sequences between the two sets of synchronization sequences of short preambles with different bandwidths are different, the lengths of the correlation peak shifts are different. For every bandwidth difference of i (MHz), the shift length increases by N. By comparing the values ​​after superimposing the shifts of different correlation peaks, the correlation calculation result is much greater when the sequences are perfectly aligned than in other cases. The waveform bandwidth used by the transmitter can be inferred from the shift interval.

[0039] 4) After determining the waveform bandwidth used by the transmitter, accurately extract the long preamble and data symbols, and pass them along with the bandwidth parameters to the subsequent baseband processing module.

[0040] by Figure 4For example, assuming the transmitter uses bandwidth B2 to send the waveform, after the local sequence at the receiver is correlated with the short preamble, for the receiver bandwidth assumption that matches the transmitter bandwidth B2, the two sets of correlation peaks, after being shifted and superimposed, will produce the maximum correlation peak value. However, for other bandwidth assumptions besides B2, because the length of the irrelevant sequence does not match the actual received waveform, the correlation peaks, after being shifted and superimposed, cannot form a peak value equivalent to the perfectly aligned state. The calculated synchronization correlation peak value is much smaller than the correlation peak value corresponding to the B2 bandwidth assumption. Therefore, by comparing the peak value after the correlation peaks are shifted and superimposed under each bandwidth assumption, the bandwidth used by the transmitter waveform can be accurately identified. Using this method, the short preamble ZC sequence is the same for each bandwidth, the receiver's local sequence is consistent, and only the irrelevant sequence interval length between the short preamble sequences differs. Therefore, the correlation calculation only needs to be performed once, resulting in low FPGA resource overhead.

[0041] The “baseband processing parameters” include waveform bandwidth, modulation scheme, coding rate and subcarrier allocation information. The physical layer receiver configures the FFT size, subcarrier mapping scheme and demapping scheme of the OFDM demodulation module according to the identified waveform bandwidth and other baseband processing parameters.

[0042] Step 4: Signal quality assessment and reporting The physical layer receiver calculates the error vector magnitude (EVM) of each subcarrier for the frequency-domain OFDM symbols obtained after OFDM demodulation in step 3. The EVM value represents the degree of closeness between the I and Q components of the received modulated signal and the ideal signal components, and its RMS value can be calculated using the following formula: in, The total number of symbols, and The first Measurements of the in-phase and quadrature components of each received symbol. and For the corresponding ideal constellation coordinates, and The normalization scaling factor for the measurement symbol and the ideal symbol. Let be the average symbol power. To reduce computational complexity in FPGA implementation, the above formula can be simplified to the following in this embodiment: in, Indicates the first The ideal constellation coordinates for receiving the symbol. Indicates the first The coordinates of the constellation points for each received symbol. If the signal is random and the constellation diagram is uniformly distributed, only the numerator needs to be calculated to replace the EVM value. When the number of symbols T is an integer, division can be achieved by shifting. Therefore, each EVM calculation only requires addition and squaring operations.

[0043] During calculation, only the EVM value is calculated for the data subcarriers within the bandwidth; guard subcarriers and pilot subcarriers are not included in the calculation. When the bandwidth is large, there are many subcarrier points. The subcarriers are grouped, and the number of subcarriers in each group is N. Calculate the average EVM value of the subcarriers in each group: in, and These are the squares of the differences between the real and imaginary parts of each subcarrier. Subcarrier groups are numbered. The error vector amplitude value of each subcarrier in the data message is calculated. The calculated error vector amplitude value of each subcarrier in the data message is used as the signal quality assessment result and reported to the MAC layer along with the demodulated and recovered data message in step 3. The smaller the error vector amplitude value, the better the signal quality on the corresponding subcarrier.

[0044] In algorithm design, the signal-to-noise ratio (SNR) is generally used as a parameter to characterize signal quality. However, in engineering implementation, calculating the SNR introduces complex computational problems, leading to excessive FPGA computation and resource saturation. Therefore, to simplify computation and reduce complexity, this invention selects the error vector amplitude value of the demapping module as a parameter to characterize signal quality. Here, the error vector amplitude value refers to the distance between the received subcarrier mapped constellation point and the standard constellation point. The smaller the error vector amplitude value, the smaller the constellation point deviation and the better the signal quality. Therefore, when the error vector amplitude value calculated by the physical layer is higher than the preset communication threshold, it indicates that there may be interference at the frequency point corresponding to this subcarrier. If the overall error vector amplitude values ​​of all subcarriers are high, it may be due to long transmission distance or high environmental noise.

[0045] The physical layer receiver reports the error vector magnitude values ​​of each subcarrier to the MAC layer as signal quality assessment parameters, without calculating the signal-to-noise ratio separately. In baseband processing, the physical layer receiver only performs fixed-point arithmetic on the error vector magnitude values, avoiding floating-point arithmetic operations involving division or logarithms to reduce FPGA resource consumption and computational complexity.

[0046] Step 5: Channel Probe Within the network, nodes coordinate the timing of sending probe messages to other nodes according to agreements between neighboring nodes, ensuring that each node sends probe messages sequentially during non-conflicting idle time slots. The probe messages use the maximum bandwidth waveform supported by the system and are periodically sent in preset frequency steps within available frequency bands outside the current operating frequency band until all supported frequency bands are covered. The probe messages are used to detect the signal quality at frequencies outside the current operating frequency band, and the MAC layer receives the error vector amplitude values ​​of each frequency point from the probe messages fed back from the physical layer.

[0047] In addition to receiving signal quality feedback from data messages, the MAC layer also sends probe messages during idle time slots between nodes in the ad hoc network to periodically check the signal quality of other available frequency bands. The physical layer also feeds back the signal quality calculation results of the probe messages to the MAC layer. The probe message bandwidth uses the maximum bandwidth waveform supported by the system, and probe messages are sent periodically within the available frequency bands until all supported frequency bands are covered. Upon receiving a probe message, the physical layer automatically identifies the waveform bandwidth used in the probe message, calculates the signal quality of the data received in the currently used frequency band, and uploads the result to the MAC layer.

[0048] The distinction between probe messages and data messages is as follows: the physical frame header of a probe message carries a specific frame type identifier field. After the physical layer receiver receives the signal, it first completes synchronization and bandwidth identification through preamble detection, and then parses the frame type identifier field in the physical frame header. If it is determined to be a probe message, the error vector amplitude value of the frame is marked as "error vector amplitude value of probe message" and reported to the MAC layer. If it is determined to be a data message, it is marked as "error vector amplitude value of data message" and reported to the MAC layer.

[0049] Step 6: Bandwidth Adjustment Decision The MAC layer comprehensively determines the bandwidth corresponding to the available continuous frequency band that meets the communication threshold based on the error vector amplitude values ​​of each subcarrier in the data message and the error vector amplitude values ​​of each frequency point in the probe message. Then, based on the comparison between the bandwidth corresponding to this available continuous frequency band and the current waveform bandwidth, it decides whether to switch the waveform bandwidth in the next scheduling cycle and to which waveform bandwidth to switch to, generating a bandwidth switching decision and sending it to the physical layer for execution. Specifically: The error vector amplitude value of each frequency point is compared with a preset communication threshold. Frequency points that meet the communication threshold are divided into continuous frequency bands, and the bandwidth value of each continuous frequency band is calculated. If the error vector amplitude value of some frequency points exceeds the threshold due to channel interference, long transmission distance, high noise floor, etc., the frequency points with poor channel quality are recorded.

[0050] Available continuous frequency bands are derived from the traversal results of probe messages. The MAC layer obtains the error vector amplitude values ​​of each frequency point in all frequency bands supported by the system by sending the probe messages described in step 5. For each frequency point, if its error vector amplitude value is lower than or equal to a preset communication threshold, the frequency point is determined to be available; adjacent available frequency points are merged into continuous frequency bands, the number of frequency points contained in each continuous frequency band is counted, and multiplied by the frequency interval between adjacent frequency points to obtain the bandwidth value corresponding to the continuous frequency band.

[0051] After completing the detection and traversal of all frequency bands, based on the feedback results of the full frequency point traversal, compare the error vector amplitude value of each frequency point with the communication threshold, and check whether the bandwidth of the continuous frequency bands of the available frequency points is greater than the waveform bandwidth currently being used by the data messages between the current ad hoc network nodes. The following two cases are used for judgment: If there exists a continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, it is determined that the bandwidth increment condition is met. In the next scheduling cycle, the waveform bandwidth of the data message will be incremented by a step value based on the current bandwidth. The step value is 10% of the current data message waveform bandwidth.

[0052] If there is no continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then record the maximum bandwidth value of the continuous frequency points within the available frequency band that meets the communication threshold, and adjust the waveform bandwidth of the data message to 80% of this maximum bandwidth value in the next scheduling cycle.

[0053] This allows for a gradual increase in the system's maximum throughput while ensuring reliability; if no wider continuous frequency band meets the requirements, the system reverts to a conservative bandwidth, maximizing throughput while maintaining reliability.

[0054] Using this method, probe messages are periodically sent during idle time slots to summarize available frequency bands in real time, allowing for the selection of appropriate frequency points and waveform bandwidths. Theoretically sound and feasible, this method also features low computational complexity and millisecond-level latency during FPGA implementation.

[0055] FPGA implementation device A subcarrier-based intelligent waveform recognition FPGA implementation device is applied to a wireless ad hoc OFDM communication system. Each node of the wireless ad hoc OFDM communication system includes a MAC layer processing module, a physical layer transmitting module, and a physical layer receiving module, comprising: The MAC layer processing module is used to allocate waveform bandwidth to each node during network establishment; to receive the subcarrier error vector amplitude values ​​reported by the physical layer during communication, and to control the physical layer transmission module to send probe messages to other nodes in the ad hoc network during idle time slots to detect the signal quality of other frequency points outside the current operating frequency band; and to comprehensively determine the bandwidth corresponding to the available continuous frequency band that meets the communication threshold based on the error vector amplitude values ​​of the data message and the probe message, and to generate a bandwidth switching decision based on the comparison result of the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth, and send it to the physical layer. Specifically, the MAC layer processing module generates the bandwidth switching decision based on the comparison result of the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth, and performs the following logical judgments: The error vector amplitude value of each frequency point is compared with the preset communication threshold. The frequency points that meet the communication threshold are divided into continuous frequency bands, and the bandwidth value of each continuous frequency band is calculated. If there exists a continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then a decision is generated to increase the data message waveform bandwidth by 10% of the current bandwidth in the next scheduling cycle. If there is no continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then record the maximum bandwidth value that is continuous within the available frequency band and meets the communication threshold, and generate a decision to adjust the data message waveform bandwidth to 80% of this maximum bandwidth value in the next scheduling cycle.

[0056] The physical layer transmission module receives bandwidth switching decisions and data messages to be transmitted from the MAC layer processing module. Based on the allocated waveform bandwidth, it determines the number of effective subcarriers for the OFDM symbols carrying the data. It then performs OFDM modulation on the data messages according to the determined number of effective subcarriers and frames them for transmission. The physical layer transmission module maintains the RF clock frequency, RF local oscillator frequency, and RF sampling rate constant when the waveform bandwidth changes, and achieves the change in waveform bandwidth by adjusting the number of effective subcarriers allocated within the OFDM symbol.

[0057] Before performing OFDM modulation on the data message according to the determined number of effective subcarriers, the physical layer transmission module is also used to independently configure the power coefficients of the effective subcarriers under different bandwidths. During OFDM modulation, the corresponding transmit power is allocated to each effective subcarrier under different bandwidths to keep the total RF output power consistent across different waveform bandwidths. The power adjustment ratio corresponds to the bandwidth ratio; that is, when the bandwidth is reduced to 1 / M of the original, the transmit power of the effective subcarrier is increased to M times the original.

[0058] The physical layer receiving module is used to autonomously identify the waveform bandwidth used by the current physical layer transmitting module based on the preamble information of the received signal, without requiring the MAC layer processing module to provide baseband processing parameters in advance. Based on the identified waveform bandwidth, it performs OFDM demodulation and subsequent baseband processing on the received signal. The subsequent baseband processing includes channel estimation, equalization, and demapping, where OFDM demodulation yields frequency-domain OFDM symbols. The physical layer receiving module is also used to calculate the error vector magnitude values ​​of each subcarrier of the frequency-domain OFDM symbols obtained after OFDM demodulation, calculate the error vector magnitude values ​​of each subcarrier of the data message, and report the calculated error vector magnitude values ​​of each subcarrier of the data message as a signal quality assessment result along with the demodulated and recovered data message to the MAC layer processing module.

[0059] The connections and data flows between the modules are as follows: Transmission direction: The MAC layer processing module sends the data message to be transmitted and the waveform bandwidth parameters to the physical layer transmission module; the physical layer transmission module determines the number of effective subcarriers according to the waveform bandwidth parameters, configures the power coefficient of each effective subcarrier, and then sequentially performs randomization, LDPC encoding, QAM mapping, OFDM modulation (IFFT), and adds a cyclic prefix, and frames it with the preamble data before outputting it to the RF interface module; the RF interface module converts the baseband signal into an RF signal and transmits it through the antenna.

[0060] Receiving direction: The RF interface module converts the RF signal received by the antenna into a baseband signal and outputs it to the physical layer receiving module; the physical layer receiving module first performs preamble detection and bandwidth identification by the synchronization module, and then performs OFDM demodulation (CP removal, FFT), channel estimation, equalization, QAM demapping, LDPC decoding and derandomization according to the identified waveform bandwidth to recover the data message; at the same time, the physical layer receiving module calculates the error vector amplitude value of each subcarrier according to the frequency domain OFDM symbols obtained after OFDM demodulation; the physical layer receiving module reports the recovered data message and the corresponding error vector amplitude value to the MAC layer processing module.

[0061] When the physical layer receiving module uploads a data message to the MAC layer processing module, it appends an interface message carrying the error vector amplitude values ​​of each subcarrier of this data message to the data frame header. The interface message also includes a frame type identifier field to distinguish whether the currently reported error vector amplitude values ​​are from a data message or a probe message. The specific format of the interface message can adopt the TLV format or a fixed field format known in the art; this embodiment does not limit this.

[0062] The radio frequency (RF) interface module is used to connect to the RF unit, enabling the conversion and transmission / reception of baseband signals and RF signals. In this embodiment, the RF unit is an AD9361, and the RF interface module connects to the RF unit through its parallel data interface. The data bit width and clock frequency are determined based on the baseband sampling rate, and can be configured according to the specific hardware platform by those skilled in the art.

[0063] Intelligent Waveform Recognition FPGA Implementation and Experimental Results The FPGA implementation of this invention uses the Zynq-7000 SoC development platform, and the software uses the Vivado 2018.3 integrated development environment and SDK 2018.3 from Xilinx for developing programmable hardware. Due to hardware platform limitations, the maximum waveform bandwidth selectable in this embodiment is 40MHz, but the technology designed in this invention is not limited to this; theoretically, if the hardware platform allows, it can be adapted to waveforms of any bandwidth.

[0064] After completing the design and FPGA implementation of the intelligent waveform recognition technology, hardware testing was conducted. The code was downloaded to the chip for board-level testing, and the performance was compared with that of the fixed bandwidth test. The hardware used in the comparison tests was identical. The test results are as follows: Figure 5 As shown, the results demonstrate that the intelligent waveform recognition technology of this invention ensures high throughput performance of broadband waveforms under short-range communication conditions and takes into account the anti-interference performance of narrowband waveforms under long-range communication conditions, maximizing system capacity while ensuring system stability and reliability. Compared with traditional adaptive bandwidth methods, this invention does not require reconfiguration of radio frequency when switching bandwidth, can adapt to changes in wireless channels in real time, maintain network stability, and has high practicality.

[0065] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A subcarrier-based intelligent waveform recognition method, applied to a wireless ad hoc OFDM communication system, wherein each node of the wireless ad hoc OFDM communication system includes a MAC layer, a physical layer transmitter, and a physical layer receiver, characterized in that, Includes the following steps: Step 1: Before networking, each node in the self-organizing network uses a unified default bandwidth waveform to transmit control messages to complete the networking. After networking, waveform bandwidth is allocated for communication between nodes. Step 2: The physical layer transmitter determines the number of effective subcarriers of the OFDM symbol used to carry data based on the currently allocated waveform bandwidth, and performs OFDM modulation on the data message according to the determined number of effective subcarriers and transmits it; when the waveform bandwidth changes, the physical layer transmitter performs a bandwidth switching operation. During the bandwidth switching process, the radio frequency clock frequency, radio frequency local oscillator frequency and radio frequency sampling rate of the physical layer transmitter remain unchanged, and the change in waveform bandwidth is only achieved by adjusting the number of effective subcarriers allocated within the OFDM symbol; Step 3: The physical layer receiver autonomously identifies the waveform bandwidth used by the current physical layer transmitter based on the preamble information of the waveform in the received signal, without the MAC layer needing to inform it of the baseband processing parameters in advance. Based on the identified waveform bandwidth, the receiver performs OFDM demodulation and subsequent baseband processing on the received signal, wherein OFDM demodulation yields frequency domain OFDM symbols. Step 4: The physical layer receiver calculates the error vector amplitude value of each subcarrier of the frequency domain OFDM symbol obtained after OFDM demodulation in step 3, and calculates the error vector amplitude value of each subcarrier of the data message. The calculated error vector amplitude value of each subcarrier of the data message is used as the signal quality assessment result and reported to the MAC layer along with the data message recovered by demodulation in step 3. The magnitude of the error vector amplitude value is inversely proportional to the signal quality on the corresponding subcarrier. Step 5: During idle time slots between nodes in the ad hoc network, the MAC layer controls the physical layer transmitter to send probe messages to other nodes in the ad hoc network. The probe messages are used to detect the signal quality of other frequency points outside the current operating frequency band. The MAC layer receives the error vector amplitude values ​​of each frequency point from the probe messages fed back by the physical layer. Step 6: The MAC layer comprehensively judges the bandwidth corresponding to the available continuous frequency band that meets the communication threshold based on the error vector amplitude values ​​of each subcarrier of the data message and the error vector amplitude values ​​of each frequency point of the probe message. Based on the comparison result between the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth, it decides whether to switch the waveform bandwidth in the next scheduling cycle and to which waveform bandwidth to switch to, generates a bandwidth switching decision, and sends it to the physical layer for execution.

2. The intelligent waveform recognition method based on subcarriers according to claim 1, characterized in that, In step 6, the MAC layer determines whether to switch the waveform bandwidth and to which waveform bandwidth to switch in the next scheduling cycle based on the comparison result between the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth. Specifically, this includes: The error vector amplitude value of each frequency point is compared with the preset communication threshold. The frequency points that meet the communication threshold are divided into continuous frequency bands, and the bandwidth value of each continuous frequency band is calculated. If there exists a continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then the bandwidth increment condition is met. In the next scheduling cycle, the waveform bandwidth of the data message will be increased by a step value based on the current bandwidth, where the step value is 10% of the current data message waveform bandwidth. If there is no continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then record the maximum bandwidth value of the continuous frequency points within the available frequency band that meets the communication threshold, and adjust the waveform bandwidth of the data message to 80% of this maximum bandwidth value in the next scheduling cycle.

3. The intelligent waveform recognition method based on subcarriers according to claim 1, characterized in that, In step 2, before the physical layer transmitter performs OFDM modulation on the data message according to the determined number of effective subcarriers, a subcarrier power adjustment step is also included: The physical layer transmitter configures the power coefficient of each effective subcarrier under different bandwidths independently. During OFDM modulation, it allocates the corresponding transmit power to each effective subcarrier under different bandwidths so that the total RF output power under different waveform bandwidths remains consistent.

4. The intelligent waveform recognition method based on subcarriers according to claim 1, characterized in that, In step 4, the physical layer receiver reports the error vector amplitude value of each subcarrier to the MAC layer as a signal quality assessment parameter, without calculating the signal-to-noise ratio separately. The physical layer receiver only performs fixed-point arithmetic on the error vector amplitude value in the baseband processing, without performing floating-point arithmetic on the signal-to-noise ratio involving division or logarithms, so as to reduce FPGA resource consumption and computational complexity.

5. The intelligent waveform recognition method based on subcarriers according to claim 1, characterized in that, In step 3, the physical layer receiver autonomously identifies the waveform bandwidth used by the current physical layer transmitter based on the preamble information of the waveform in the received signal. Specifically, this includes: The synchronization module of the physical layer receiver performs preamble detection on the received signal, extracts bandwidth identification features from the preamble information of the waveform in the signal, matches the extracted bandwidth identification features with the preset preamble features of various bandwidth waveforms supported by the system, determines the waveform bandwidth used by the current physical layer transmitter based on the matching result, and configures OFDM demodulation parameters according to the waveform bandwidth.

6. The intelligent waveform recognition method based on subcarriers according to claim 1, characterized in that, In step 1, the default bandwidth waveform used by each node before networking is the narrowband waveform with the highest reliability among the various bandwidth waveforms supported by the system.

7. The intelligent waveform recognition method based on subcarriers according to claim 1, characterized in that, In step 5, the MAC layer controls the physical layer transmitter to send probe messages to other nodes in the ad hoc network during idle time slots between nodes within the ad hoc network. Specifically, this includes: According to the agreement between neighboring nodes, the nodes in the network coordinate the time when each node sends probe messages to other nodes, so that each node sends probe messages in turn during idle time slots that do not conflict with each other. The probe messages use the maximum bandwidth waveform supported by the system and are sent periodically in preset frequency steps in other available frequency bands outside the current operating frequency band until all frequency bands supported by the system are covered.

8. A subcarrier-based intelligent waveform recognition FPGA implementation device, applied to a wireless ad hoc OFDM communication system, wherein each node of the wireless ad hoc OFDM communication system includes a MAC layer processing module, a physical layer transmitting module, and a physical layer receiving module, characterized in that, include: The MAC layer processing module is used to allocate waveform bandwidth to each node during network establishment. Used to receive the error vector amplitude values ​​of each subcarrier reported by the physical layer during communication, and to control the physical layer transmission module to send probe messages to other nodes in the ad hoc network in the idle time slot to detect the signal quality of other frequency points outside the current working frequency band; used to comprehensively determine the bandwidth corresponding to the available continuous frequency band that meets the communication threshold based on the error vector amplitude values ​​of the data message and the probe message, and to generate a bandwidth switching decision and send it to the physical layer based on the comparison result between the bandwidth corresponding to the available continuous frequency band and the current waveform bandwidth; The physical layer transmission module receives bandwidth switching decisions and data messages to be transmitted from the MAC layer processing module. It determines the number of effective subcarriers for the OFDM symbols used to carry the data based on the allocated waveform bandwidth, performs OFDM modulation on the data messages according to the determined number of effective subcarriers, and frames and transmits them. The physical layer transmission module maintains the RF clock frequency, RF local oscillator frequency, and RF sampling rate constant when the waveform bandwidth changes, and achieves the change in waveform bandwidth by adjusting the number of effective subcarriers allocated within the OFDM symbol. The physical layer receiving module is used to autonomously identify the waveform bandwidth used by the current physical layer transmitting module based on the preamble information of the waveform in the received signal, without requiring the MAC layer processing module to inform it of the baseband processing parameters in advance. Based on the identified waveform bandwidth, it performs OFDM demodulation and subsequent baseband processing on the received signal, whereby OFDM demodulation yields frequency-domain OFDM symbols. The physical layer receiving module is also used to calculate the error vector amplitude value of each subcarrier in the frequency-domain OFDM symbols obtained after OFDM demodulation, calculate the error vector amplitude value of each subcarrier in the data message, and report the calculated error vector amplitude values ​​of each subcarrier in the data message as a signal quality assessment result along with the demodulated and recovered data message to the MAC layer processing module. The radio frequency interface module is used to connect to the radio frequency unit and realize the conversion and transmission and reception between baseband signals and radio frequency signals.

9. The FPGA implementation device for intelligent waveform recognition based on subcarriers according to claim 8, characterized in that, The MAC layer processing module generates a bandwidth switching decision based on a comparison between the bandwidth corresponding to the available continuous frequency band and the bandwidth of the current waveform. Specifically, it performs the following logical judgments: The error vector amplitude value of each frequency point is compared with the preset communication threshold. The frequency points that meet the communication threshold are divided into continuous frequency bands, and the bandwidth value of each continuous frequency band is calculated. If there exists a continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then a decision is generated to increase the data message waveform bandwidth by 10% of the current bandwidth in the next scheduling cycle. If there is no continuous frequency band bandwidth greater than 1.2 times the current data message waveform bandwidth, then record the maximum bandwidth value that is continuous within the available frequency band and meets the communication threshold, and generate a decision to adjust the data message waveform bandwidth to 80% of this maximum bandwidth value in the next scheduling cycle.

10. The FPGA implementation device for intelligent waveform recognition based on subcarriers according to claim 8, characterized in that, Before performing OFDM modulation on the data message according to the determined number of effective subcarriers, the physical layer transmission module is also used to configure the power coefficients of the effective subcarriers under different bandwidths independently. During OFDM modulation, the corresponding transmission power is allocated to each effective subcarrier under different bandwidths so that the total RF output power under different waveform bandwidths remains consistent.

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