Communication system and method for heterogeneous internet of things protocol concurrent transmission

Abstract

The invention discloses a communication system and method for heterogeneous Internet of Things protocol concurrent transmission. The method comprises the following steps: firstly, performing sampling rate synchronization and frame structure alignment on WiFi signals and ZigBee signals in a signal preprocessing stage; secondly, constructing a candidate QAM point set, and selecting a mixed QAM point which has the minimum Hamming distance with the QAM point of the original WiFi and the minimum Euclidean distance with the ZigBee signal so as to generate a concurrent signal; and finally, the mixed signal is transmitted to WiFi and ZigBee receiving equipment, so that the WiFi and ZigBee receiving equipment can correctly identify the corresponding signal. According to the method, the WiFi and ZigBee data packets are concurrently transmitted on the premise of no packet loss by utilizing an inherent error code fault-tolerant mechanism of WiFi and ZigBee physical layers, so that the spectrum efficiency and throughput of the heterogeneous Internet of Things network are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the technical field of wireless communication and the Internet of Things, specifically relating to a communication system and method for concurrent transmission of heterogeneous Internet of Things protocols. Background Technology

[0002] In recent decades, the Internet of Things (IoT) has experienced explosive growth in various fields such as smart homes, smart factories, and smart transportation systems. Forecasts indicate that the number of wireless devices worldwide will grow to approximately one trillion by 2035. Among these, WiFi devices have become integrated into daily life, while the deployment of ZigBee devices has sparked a significant surge in the modern smart environment.

[0003] However, due to widespread spectrum coexistence, interference, and collisions, spectral efficiency can be severely degraded when heterogeneous wireless devices are densely deployed. Specifically, both WiFi and ZigBee signals operate in the 2.4 GHz band, and the presence of these devices in the same environment can lead to significant cross-technology interference. While CSMA / CA mechanisms are typically used to prevent collisions, this also reduces spectral efficiency.

[0004] Therefore, a method capable of simultaneously transmitting WiFi and ZigBee signals without backoff to prevent collisions is needed, which is crucial for improving overall spectrum utilization efficiency. However, the incompatibility of the physical layer in heterogeneous IoT presents significant technical challenges in achieving this goal. Summary of the Invention

[0005] This invention addresses the problem of low overall spectral efficiency caused by WiFi and ZigBee devices operating in the same scenario. It provides a communication system and method for concurrent transmission of heterogeneous IoT protocols. First, in the signal preprocessing stage, the sampling rate of the WiFi and ZigBee signals is synchronized and the frame structure is aligned. Second, by constructing a candidate QAM point set, a hybrid QAM point with the smallest Hamming distance to the original WiFi QAM point and the smallest Euclidean distance to the ZigBee signal is selected to generate a concurrent signal. Finally, this hybrid signal is transmitted to the WiFi and ZigBee receiving devices so that they can correctly identify the corresponding signals. This invention utilizes the inherent error-tolerant mechanisms of the WiFi and ZigBee physical layers to achieve concurrent transmission of WiFi and ZigBee data packets without packet loss, significantly improving the spectral efficiency and throughput of heterogeneous IoT networks.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a communication method for concurrent transmission of heterogeneous Internet of Things protocols, comprising the following steps:

[0007] S1. Signal preprocessing and synchronization alignment: Input the original WiFi transmission request signal and ZigBee transmission request signal, perform sampling rate synchronization and frame structure alignment operations on the two signals, and obtain the synchronized WiFi signal and ZigBee signal.

[0008] S2. Hybrid QAM Point Optimization Selection: Input the synchronized WiFi signal and ZigBee signal obtained in step S1 to the Hamming distance modulation module to construct a candidate QAM point set. Select the hybrid QAM point with the smallest Hamming distance to the original WiFi transmission request signal and the smallest Euclidean distance to the ZigBee transmission request signal to generate a concurrent signal and obtain a hybrid baseband signal; the candidate QAM point set CQS is specifically as follows:

[0009] ;

[0010] Wherein, CQS is the candidate quadrature amplitude modulation (QAM) point set, that is, the set of all QAM constellation points that satisfy the error tolerance condition of WiFi signal; p is any QAM constellation point in the candidate QAM point set; QAM is the set of quadrature amplitude modulation constellation diagrams; The Hamming distance represents the number of distinct bits between the binary bitstream corresponding to candidate QAM point p and the binary bitstream corresponding to the original WiFi signal QAM point w; w is the original QAM constellation point obtained after orthogonal amplitude modulation of the original WiFi transmission request signal. The selection criterion is that the bit difference between the candidate QAM point p and the original WiFi QAM point w does not exceed 1 bit, ensuring that the WiFi receiver can correctly demodulate through the physical layer error tolerance mechanism.

[0011] S3. Concurrent signal RF transmission: Input the mixed baseband signal from step S2 to the RF transmission module. After frequency domain conversion and RF processing, the concurrent signal is sent to the target receiving device to realize the concurrent transmission of WiFi and ZigBee signals.

[0012] As an improvement of the present invention, step S1 specifically includes the following steps:

[0013] S11. Signal Rate Adaptation Processing: Inputting the original WiFi transmission request signal and the ZigBee transmission request signal, the data packets of the ZigBee transmission request signal are transmitted at a specified frequency to direct sequence spread spectrum and pulse shaping. Direct sequence spread spectrum is implemented using a pseudo-random code (PN code). The spread signal expression is as follows: , This is raw ZigBee data. It is a pseudo-random code. (Carrier angular frequency) to achieve spectrum spread to improve anti-interference capability; pulse shaping adopts raised cosine roll-off filter; at the same time, the data packets of WiFi transmission request signal are initially processed by standard modulation protocol to unify the rate of the two types of signals, resulting in WiFi preprocessed signal and ZigBee preprocessed signal with unified rate.

[0014] S12, Frame Structure Segment Alignment: Perform frame structure segment alignment on the WiFi preprocessed signal and ZigBee preprocessed signal with uniform rate obtained in step S11. Divide the discrete baseband symbol of the ZigBee preprocessed signal into four segments. Each segment corresponds to the part of the WiFi preprocessed signal output in step S11 that does not include the cyclic prefix and is mixed. At the same time, the cyclic prefix part of the WiFi preprocessed signal output in step S11 is assigned as the corresponding time domain ZigBee signal to obtain the WiFi signal and ZigBee signal after the sampling rate is synchronized and the frame structure is aligned.

[0015] As another improvement of the present invention, the initial processing of the WiFi transmission request signal data packet in step S12 includes at least channel coding and quadrature amplitude modulation. The channel coding adopts binary convolutional coding with a coding rate of 1 / 2 and a generator polynomial of... , The orthogonal amplitude modulation uses 64-QAM modulation, with each symbol mapping 6 bits, and the constellation point coordinates are... The pairwise combination of the modulated signal is expressed as: ,in .

[0016] As another improvement of the present invention, step S2 specifically includes the following steps:

[0017] S21. Subcarrier SNR Evaluation: Input the synchronized WiFi signal, the system sends the WiFi signal to the receiver and evaluates the attenuation of the received signal, calculates the signal-to-noise ratio of each subcarrier, and obtains the signal-to-noise ratio data of each subcarrier.

[0018] S22. Dynamic configuration of error tolerance bits: Input the signal-to-noise ratio (SNR) data of each subcarrier. For subcarriers with high SNR, the error tolerance bit tolerance is relaxed to at least two bits; for subcarriers with low SNR, the error tolerance bit tolerance bit is retained to 1 bit. Obtain the error tolerance bit configuration parameters for each subcarrier.

[0019] S23. Candidate QAM Point Set Construction: Input the synchronized WiFi signal and the error tolerance bit configuration parameters of each subcarrier. Calculate the candidate QAM point set according to the error tolerance bit threshold. A candidate QAM point set differing by 1 bit is defined as... , where w is the QAM point of the synchronized WiFi signal, HD represents the Hamming distance, and the candidate QAM point set corresponding to each subcarrier is obtained;

[0020] S24, ZigBee Amplitude and Phase Optimization: Input the synchronized ZigBee signal and candidate QAM point set, keep the phase shift between two adjacent ZigBee sampling data unchanged, adjust its amplitude and phase in ZigBee signal segments to make it close to the candidate QAM point set, and obtain the optimized ZigBee signal mapping points.

[0021] S25. Determining the optimal mixed QAM point: Input candidate QAM point set ( Mapping points between candidate orthogonal amplitude modulation constellation points and optimized ZigBee signal Using the Euclidean distance formula Where M is the dimension of the constellation point, Candidate QAM points The 3D coordinates The first point z of the ZigBee signal mapping Using 3D coordinates, calculate the Euclidean distance between each candidate QAM point and the ZigBee signal mapping point, and select the point with the smallest distance as the QAM point of the final mixed signal to obtain the mixed baseband signal.

[0022] To achieve the above objectives, the present invention also adopts the following technical solution: a communication system for concurrent transmission of heterogeneous Internet of Things protocols, comprising at least a signal preprocessing module, a Hamming distance modulation module, and a radio frequency transmission module.

[0023] The signal preprocessing module transmits the data packets in the input ZigBee transmission request signal to direct sequence spread spectrum and pulse shaping at a specified frequency. Simultaneously, after performing initial processing on the data packets in the input WiFi transmission request signal based on the standard modulation protocol, it segments the ZigBee signal after direct sequence spread spectrum and pulse shaping, and performs alignment operation on the frame structure of the initially processed WiFi data packet signal after removing the cyclic prefix, thereby achieving time-domain synchronization of the two types of signals and obtaining WiFi signal and ZigBee signal after sampling rate synchronization and frame structure alignment.

[0024] The Hamming distance modulation module: based on the bit-level robustness of WiFi binary convolutional coding and ZigBee direct sequence spread spectrum, and according to the quantization relationship between Hamming distance and Euclidean distance in the constellation diagram, constructs a candidate QAM point set and selects the optimal hybrid QAM point to obtain a hybrid baseband signal carrying two types of signal information;

[0025] The radio frequency transmission module: inputs a mixed baseband signal, converts it to the frequency domain through a fast Fourier transform, processes it through the radio frequency front end, and then sends the mixed concurrent signal to the target WiFi and ZigBee receiving devices, realizing concurrent and reliable transmission of heterogeneous signals.

[0026] As an improvement of the present invention, the method for selecting the optimal hybrid QAM point in the Hamming distance modulation module is as follows: Input the candidate QAM point set and the ZigBee signal constellation map mapping points; use Parseval's theorem to equate the ZigBee time-domain deviation to the frequency-domain Euclidean distance; calculate and select the QAM point with the smallest Euclidean distance to the ZigBee mapping points; and output the optimal hybrid QAM point adapted to demodulation of the two types of signals; wherein the formula of Parseval's theorem is... This is used to establish the equivalence relationship between the time-domain discrete signal error and the frequency-domain discrete signal error of ZigBee, and to realize the frequency-domain quantization calculation of the time-domain deviation. and It is a discrete-time signal. For time-domain sampling point index; It is the total energy of the time-domain signal error; and It is a discrete signal in the frequency domain. and The result after N-point Fast Fourier Transform (FFT) For frequency domain subcarriers or frequency point indexes; It is the total energy of the frequency domain signal error.

[0027] As another improvement of the present invention, the Hamming distance modulation module further includes adjusting the amplitude and overall phase of the ZigBee signal, inputting the distribution information of ZigBee signal segments and candidate QAM point sets, keeping the phase shift of adjacent ZigBee sampling data unchanged, adjusting the amplitude and overall phase in units of ZigBee signal segments, and outputting ZigBee signal mapping points close to the candidate QAM point sets.

[0028] As another improvement of the present invention, the system also supports subcarrier error allocation, which increases the error tolerance bits of subcarriers with high signal-to-noise ratios to at least 2 bits based on the signal-to-noise ratio of the subcarriers.

[0029] Compared with the prior art, the technical effects and advantages of the present invention are as follows:

[0030] (1) The communication system and method for concurrent transmission of heterogeneous IoT protocols proposed in this invention can realize a solution that supports the simultaneous transmission of WiFi and ZigBee signals in the same frequency band in the same scenario with a much lower bit error rate than existing methods. The method of this invention only requires the deployment of this system at the signal transmitting end, mixing and modulating the input WiFi and ZigBee data, and transmitting the mixed signal to the WiFi receiving device and ZigBee receiving device at the receiving end. The mixed signal can be correctly identified and received by the two types of devices respectively.

[0031] (2) The Hamming distance modulation method designed in this invention can ensure that the mixed signal can be demodulated by WiFi and ZigBee devices at the same time. The method selectively identifies WiFi bits as error bits, so that the generated signal is very similar to WiFi data packets and ZigBee signals.

[0032] (3) The proposed adjustment of the amplitude and phase of the ZigBee signal in this invention supports the selection of error bits in Hamming distance modulation, which maximizes the potential for generating concurrent mixed signals.

[0033] (4) The subcarrier error allocation proposed in this invention supports the expansion of the candidate QAM point set in Hamming distance modulation. By calculating the signal-to-noise ratio of WiFi subcarriers, the candidate QAM point set of subcarriers with high signal-to-noise ratio is expanded to further reduce the loss of ZigBee data. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0035] Figure 2 This is a schematic diagram of Hamming distance modulation in step S2 of the method of the present invention;

[0036] Figure 3 This is a schematic diagram illustrating the adjustment of the amplitude and phase of the ZigBee signal in the method of this invention;

[0037] Figure 4 This is a schematic diagram of device deployment in line-of-sight (LoS) and non-line-of-sight (NLoS) scenarios in the test examples of this invention;

[0038] Figure 5 This is a comparison chart of the packet reception rate (PRR) of this system under different scenarios in the test examples of this invention;

[0039] Figure 6 This is a comparison chart of the bit error rate (BER) of the system in different scenarios in the test examples of this invention. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] Example 1

[0042] Communication systems designed for concurrent transmission of heterogeneous IoT protocols, such as Figure 1 As shown, WiFi and ZigBee data packets are input to the signal preprocessing module and the Hamming distance modulation module, and the radio frequency transmission module generates a mixed signal and sends it to the WiFi and ZigBee receiving devices.

[0043] The system of this invention includes a signal preprocessing module for synchronizing the sampling rate and aligning the frame structure of input WiFi and ZigBee signals, a Hamming distance modulation module for selecting the optimal hybrid QAM point based on the constellation mapping relationship of WiFi and ZigBee signals, and an RF transmission module for transmitting the hybrid signal to the target receiving device.

[0044] The signal preprocessing module transmits the data packets in the input ZigBee transmission request signal to the direct sequence spread spectrum and pulse shaping at a specified frequency of 20MHz. Simultaneously, after performing initial processing on the data packets in the input WiFi transmission request signal based on the standard modulation protocol, the module segments the ZigBee signal after direct sequence spread spectrum and pulse shaping, and aligns the frame structure of the initially processed WiFi data packet signal after removing the cyclic prefix, thereby achieving time-domain synchronization of the two types of signals and obtaining WiFi and ZigBee signals after sampling rate synchronization and frame structure alignment.

[0045] The Hamming distance modulation module takes into account the synchronized WiFi signal, ZigBee signal, and signal-to-noise ratio data of each subcarrier. Relying on the bit-level robustness of WiFi binary convolutional coding and ZigBee direct sequence spread spectrum, and combining the quantization relationship between Hamming distance and Euclidean distance in the constellation diagram, it constructs a candidate QAM point set and selects the optimal hybrid QAM point to obtain a hybrid baseband signal carrying two types of signal information.

[0046] The radio frequency transmitting module takes in a mixed baseband signal, converts it to the frequency domain via a fast Fourier transform, processes it at the radio frequency front end, and then sends the mixed concurrent signal to the target WiFi and ZigBee receiving devices, thus achieving concurrent and reliable transmission of heterogeneous signals.

[0047] The Hamming distance modulation module selects the hybrid QAM points using the following formula:

[0048]

[0049] Where CQS is the candidate QAM point set, z is the ZigBee signal mapping point, and ED is the Euclidean distance.

[0050] Given a set of candidate QAM points and ZigBee signal constellation mapping points, the Parseval theorem is used to equate the ZigBee time-domain deviation to the frequency-domain Euclidean distance. The QAM points with the smallest Euclidean distance to the ZigBee mapping points are calculated and selected, and the optimal hybrid QAM points adapted for demodulation of both signal types are output. The formula for the Parseval theorem is as follows: This is used to establish the equivalence relationship between the time-domain discrete signal error and the frequency-domain discrete signal error of ZigBee, and to realize the frequency-domain quantization calculation of the time-domain deviation. and It is a discrete-time signal. For time-domain sampling point index; It is the total energy of the time-domain signal error; and It is a discrete signal in the frequency domain. and The result after N-point Fast Fourier Transform (FFT) For frequency domain subcarriers or frequency point indexes; It is the total energy of the frequency domain signal error.

[0051] The candidate QAM point set CQS is defined as:

[0052]

[0053] Where w represents the original WiFi signal QAM point, and HD represents the Hamming distance, i.e., the difference in the number of bits between two data sequences. This set is based on the original WiFi signal QAM points, combined with the bit-level error tolerance characteristics of WiFi, using a Hamming distance ≤ 1 as a threshold, and leveraging the error-resistant capability of WiFi binary convolutional coding, through Hamming distance calculation and screening of QAM points that meet the threshold condition, to obtain a candidate QAM point set that ensures the WiFi bit error rate is controllable.

[0054] The system of this invention also supports amplitude and phase adjustment to adjust the amplitude and overall phase of the ZigBee signal, making the original ZigBee signal mapping points closer to the candidate QAM point set, further reducing the overall error rate. This adjustment process takes into account the distribution information of ZigBee signal segments and candidate QAM point sets. Utilizing the characteristic that ZigBee demodulation depends only on the phase difference between adjacent samples, it maintains the phase shift of adjacent ZigBee sample data unchanged, optimizing and adjusting the amplitude and overall phase on a segment-by-segment basis, outputting ZigBee signal mapping points that are closer to the candidate QAM point set, thus providing support for the selection of the optimal hybrid QAM point.

[0055] The system of this invention also supports subcarrier error allocation, which, based on the signal-to-noise ratio (SNR) of the subcarriers, increases the error tolerance bits of subcarriers with particularly high SNR to 2 bits or more to expand their CQS, thereby further reducing the bit error rate. This allocation process takes the SNR data of each subcarrier as input, and through a series of operations including high SNR subcarrier identification, error tolerance bit threshold adjustment, and expansion of the candidate QAM point set, optimizes the demodulation performance of the ZigBee signal while ensuring the accuracy of WiFi transmission, and outputs a differentiated set of candidate QAM points for the subcarriers.

[0056] Example 2

[0057] A concurrent transmission method for heterogeneous IoT communication includes the following steps:

[0058] Step S1: Synchronize the sampling rate and align the frame structure of the input WiFi and ZigBee signals;

[0059] S11. Signal Rate Adaptation Processing: Inputting the original WiFi transmission request signal and ZigBee transmission request signal, the ZigBee transmission request signal data packets are transmitted to direct sequence spread spectrum and pulse shaping at a specified frequency of 20MHz. Simultaneously, the WiFi transmission request signal data packets undergo initial processing using a standard modulation protocol to unify the rates of the two signal types, resulting in a WiFi pre-processed signal and a ZigBee pre-processed signal with unified rates. Direct sequence spread spectrum is implemented using a pseudo-random code (PN code), and the spread signal expression is as follows: , This is raw ZigBee data. It is a pseudo-random code. (The carrier angular frequency is used to achieve spectrum spreading to improve anti-interference; pulse shaping uses a raised cosine roll-off filter;)

[0060] S12, Frame Structure Segment Alignment: Perform frame structure segment alignment on the WiFi preprocessed signal and ZigBee preprocessed signal with uniform rate obtained in step S11. Divide the discrete baseband symbol of the ZigBee preprocessed signal into four segments. Each segment corresponds to the part of the WiFi preprocessed signal output in step S11 that does not include the cyclic prefix and is mixed. At the same time, the cyclic prefix part of the WiFi preprocessed signal output in step S11 is assigned as the corresponding time domain ZigBee signal, so as to obtain the WiFi signal and ZigBee signal after the sampling rate is synchronized and the frame structure is aligned.

[0061] Step S2: Select the optimal hybrid QAM point based on the constellation mapping relationship between WiFi and ZigBee signals;

[0062] S21. Subcarrier SNR Evaluation: Input the synchronized WiFi signal, the system sends the WiFi signal to the receiver and evaluates the attenuation of the received signal, calculates the signal-to-noise ratio of each subcarrier, and obtains the signal-to-noise ratio data of each subcarrier.

[0063] S22. Dynamic configuration of error tolerance bits: Input the signal-to-noise ratio (SNR) data of each subcarrier. For subcarriers with high SNR, the error tolerance bit tolerance is relaxed to at least two bits; for subcarriers with low SNR, the error tolerance bit tolerance bit is retained to 1 bit. Obtain the error tolerance bit configuration parameters for each subcarrier.

[0064] S23. Candidate QAM point set construction: Input the synchronized WiFi signal and the error tolerance bit configuration parameters of each subcarrier, and calculate the candidate QAM point set according to the error tolerance bit threshold, i.e. Figure 2 As shown by the green dots, the candidate QAM point set that differs by 1 bit is defined as... Where w is the QAM point of the synchronized WiFi signal, i.e. Figure 2 As shown by the blue dots, HD represents the Hamming distance, and the candidate QAM point set corresponding to each subcarrier is obtained;

[0065] S24, ZigBee Amplitude and Phase Optimization: Input the synchronized ZigBee signal and candidate QAM point set, keeping the phase shift between two adjacent ZigBee sampling data unchanged, adjust its amplitude and phase in units of ZigBee signal segments to make it close to the candidate QAM point set, such as... Figure 3 As shown, the optimized ZigBee signal mapping points are obtained;

[0066] S25. Determining the optimal mixed QAM point: Input candidate QAM point set Mapping points between candidate quadrature amplitude modulation constellation points and optimized ZigBee signal ,Right now Figure 2 The red crosses in the diagram are represented by the Euclidean distance formula. Calculate the Euclidean distance between each candidate QAM point and the ZigBee signal mapping point, and select the point with the smallest distance as the final QAM point of the mixed signal to obtain the mixed baseband signal; where M is the constellation point dimension. Candidate QAM points The 3D coordinates The first point z of the ZigBee signal mapping 3D coordinates.

[0067] Step S3, Concurrent Signal RF Transmission: Input the mixed baseband signal, perform frequency domain conversion and RF processing, and send the concurrent signal to the target receiving device to achieve concurrent and reliable transmission of WiFi and ZigBee signals.

[0068] Test case

[0069] To verify the effectiveness of the proposed method, in the following ways... Figure 4 Experiments were conducted in both line-of-sight and non-line-of-sight environments, deploying several WiFi and ZigBee receivers, along with this system, to demonstrate the advantages of this solution.

[0070] The experiment was performed using the following configuration:

[0071] Hardware and software settings:

[0072] 1. MATLAB R2023a: used to implement this system;

[0073] 2. GNU Radio and USRP B210: Used for transmitting mixed signals;

[0074] 3. ZigBee device CC2530 and WiFi device AR5BXB112: as receivers for commercial devices;

[0075] 4. Connect the computer to the ZigBee CC2530: Collect and statistically analyze the received ZigBee and WiFi data by running SmartRF Studio and Wireshark;

[0076] Experimental Design:

[0077] 1. When conducting experiments under line-of-sight conditions, a device implementing this system is placed at one end of the corridor to transmit mixed signals, and a ZigBee and a WiFi receiver are placed at the other end. When conducting experiments under non-line-of-sight conditions, one CTx device, four WiFi receivers, and four ZigBee receivers are deployed in the office.

[0078] 2. Signal transmission: This system transmits mixed signals via GNU Radio and USRP B210.

[0079] 3. Data Acquisition: The computer connected to the ZigBee CC2530 collects the received data by running SmartRF Studio and Wireshark, and records the success rate and bit error rate of reception.

[0080] 4. Performance Evaluation: Under line-of-sight conditions, compare the data packet reception rate and bit error rate of the receiving device and this system at different distances, and compare the results with the benchmark method (Chiron); under non-line-of-sight conditions, compare the data packet reception rate and bit error rate of the receiving devices at different locations, and compare the results with the benchmark method.

[0081] Experimental results are as follows Figure 5and Figure 6 As shown: Figure 5 and Figure 6 The data packet reception rate and bit error rate are demonstrated respectively when using the method of this invention to concurrently transmit mixed WiFi and ZigBee signals in different scenarios. For example... Figure 5 (a) and Figure 6 As shown in (a), in a line-of-sight scenario, as the distance between the receiving device and the system device gradually increases from 4 meters to 20 meters, the reception rate of data packets of different lengths gradually decreases from nearly 100% to about 60%, while the bit error rate gradually increases, but all are significantly better than the experimental results of the benchmark method; Figure 5 (b) and Figure 6 As shown in (b), in non-line-of-sight scenarios, the average reception rate of WiFi and ZigBee data packets can reach approximately 70%, both higher than the baseline method, and the bit error rate is also lower than the baseline method. Although the performance of this system gradually deteriorates as the data packet length increases, this problem can be solved by using techniques such as retransmission or data packet segmentation.

[0082] In summary, the communication system and method proposed in this solution for concurrent transmission of heterogeneous IoT protocols can generate effective mixed WiFi and ZigBee signals and be correctly identified by each receiving device, which plays a very important role in improving the overall spectrum efficiency in heterogeneous IoT scenarios.

[0083] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A communication system for concurrent transmission of heterogeneous Internet of Things protocols, characterized in that: At least comprising a signal preprocessing module, a Hamming distance modulation module and a radio frequency transmitting module, The signal preprocessing module: delivers the data packet in the input ZigBee transmission request signal to direct sequence spread spectrum and pulse shaping according to the specified frequency, completes the initial processing of the data packet in the input WiFi transmission request signal based on the standard modulation protocol, segments the ZigBee signal after direct sequence spread spectrum and pulse shaping, removes the cyclic prefix frame structure segment of the WiFi data packet signal after initial processing and performs alignment operation, realizes time domain synchronization of the two types of signals, and obtains the WiFi signal and ZigBee signal after sampling rate synchronization and frame structure alignment; The Hamming distance modulation module: inputs the WiFi signal, ZigBee signal and subcarrier signal-to-noise ratio data after synchronization and alignment, based on the bit-level robustness of WiFi binary convolutional coding and ZigBee direct sequence spread spectrum, according to the quantization relationship between Hamming distance and Euclidean distance in constellation diagram, constructs a candidate QAM point set and selects the optimal mixed QAM point, and obtains a mixed baseband signal carrying information of the two types of signals; The radio frequency transmitting module: inputs the mixed baseband signal, converts to the frequency domain through fast Fourier transform, performs digital-to-analog conversion and radio frequency power amplification processing, and then sends the mixed concurrent signal to the target WiFi and ZigBee receiving device, realizing concurrent reliable transmission of heterogeneous signals.

2. The communication system for heterogeneous internet of things protocol concurrent transmission of claim 1, wherein: In the Hamming distance modulation module, the method for selecting the optimal mixed QAM point is: inputting the candidate QAM point set and the ZigBee signal constellation mapping point, using the Parseval theorem to equivalently convert the ZigBee time domain deviation into the frequency domain Euclidean distance, calculating and selecting the QAM point with the minimum Euclidean distance from the ZigBee mapping point, and outputting the optimal mixed QAM point suitable for demodulation of the two types of signals; the Parseval theorem is used to establish the equivalence relationship between the ZigBee time domain discrete signal error and the frequency domain discrete signal error, realize frequency domain quantization calculation of time domain deviation, and specifically: ； wherein and is a time-domain discrete signal, is a time-domain sample point index; is the total energy of the time-domain signal error; and is a frequency-domain discrete signal, is and is the result after N-point fast Fourier transform, is a frequency-domain subcarrier index; is the total energy of the frequency-domain signal error.

3. The communication system for heterogeneous internet of things protocol concurrent transmission of claim 1, wherein: The Hamming distance modulation module further comprises adjusting the amplitude and overall phase of the ZigBee signal, inputting the ZigBee signal segment and candidate QAM point set distribution information, keeping the phase shift of adjacent ZigBee sampling data unchanged, adjusting the amplitude and overall phase in units of ZigBee signal segments, and outputting the ZigBee signal mapping point close to the candidate QAM point set.

4. The communication system for heterogeneous internet of things protocol concurrent transmission of claim 1, wherein: The system also supports subcarrier error allocation, and according to the signal-to-noise ratio of the subcarrier, the error tolerance bit of the subcarrier with high signal-to-noise ratio is increased to at least 2 bits.

5. A communication method for concurrent transmission of heterogeneous IoT protocols using the system as claimed in claim 1, characterized in that, The method comprises the following steps: S1, signal preprocessing and synchronization alignment: inputting the original WiFi transmission request signal and ZigBee transmission request signal, performing sampling rate synchronization and frame structure alignment operation on the two types of signals, and obtaining the synchronized WiFi signal and ZigBee signal; S2, mixed QAM point optimization selection: input the synchronized WiFi signal and ZigBee signal obtained in step S1 into a Hamming distance modulation module, construct a candidate QAM point set, select a mixed QAM point with the minimum Hamming distance from the QAM point of the original WiFi transmission request signal and the minimum Euclidean distance from the ZigBee transmission request signal, to generate a concurrent signal, and obtain a mixed baseband signal; the candidate QAM point set CQS is specifically: ； wherein CQS is a candidate quadrature amplitude modulation (QAM) point set; p is any one QAM constellation point in the candidate QAM point set; and QAM is a constellation set of quadrature amplitude modulation. is a Hamming distance, representing the number of different bits between the binary bit stream corresponding to the candidate QAM point p and the binary bit stream corresponding to the original WiFi transmission request signal QAM point w; w is an original QAM constellation point obtained after quadrature amplitude modulation of the original WiFi transmission request signal; 6. S3, concurrent signal radio frequency transmission: input the mixed baseband signal of step S2 into a radio frequency transmission module, perform frequency domain conversion and radio frequency processing operation, send the concurrent signal to the target receiving device, and realize concurrent transmission of WiFi and ZigBee signals.

7. The communication method for heterogeneous internet of things protocol concurrent transmission according to claim 5, characterized in that: The step S1 specifically includes the following steps: S11, signal rate adaptation processing: input the original WiFi transmission request signal and the ZigBee transmission request signal, transfer the data packet of the ZigBee transmission request signal to the direct sequence spread spectrum and pulse shaping at a specified frequency, and simultaneously perform initial processing on the data packet of the WiFi transmission request signal through the standard modulation protocol, so that the rates of the two types of signals are unified, and the rate-unified WiFi preprocessed signal and ZigBee preprocessed signal are obtained; S12, frame structure segmentation alignment: perform frame structure segmentation alignment operation on the rate-unified WiFi preprocessed signal and ZigBee preprocessed signal obtained in step S11, divide the discrete baseband symbol of the ZigBee preprocessed signal into four segments, each segment corresponds to the part of the WiFi preprocessed signal output in step S11 and does not include the cyclic prefix, and simultaneously allocates the cyclic prefix part of the WiFi preprocessed signal output in step S11 as the corresponding time domain ZigBee signal, to obtain the WiFi signal and ZigBee signal after sampling rate synchronization and frame structure alignment.

8. The communication method for heterogeneous internet of things protocol concurrent transmission according to claim 6, characterized in that: In the step S11, the direct sequence spread spectrum is realized by a pseudo-random code, and a signal expression after spreading is wherein, is ZigBee original data, is a pseudo-random code, is a carrier angular frequency; and pulse shaping is realized by a raised cosine roll-off filter.

9. The communication method for heterogeneous internet of things protocol concurrent transmission according to claim 6, characterized in that: The initial processing of the data packet of the WiFi transmission request signal in the step S12 at least includes channel coding and quadrature amplitude modulation, the channel coding adopts binary convolution coding, the coding rate is 1 / 2, and the generating polynomial is 、 ; the quadrature amplitude modulation adopts 64-QAM modulation, each symbol maps 6 bits, and the constellation point coordinates are two-by-two combinations of , and the modulation signal expression is .

10. The communication method for heterogeneous internet of things protocol concurrent transmission according to claim 6, characterized in that: The step S2 specifically includes the following steps: S21, subcarrier SNR evaluation: input the synchronized WiFi signal, the system sends the WiFi signal to the receiver and evaluates the attenuation of the received signal, calculates the signal-to-noise ratio of each subcarrier, and obtains subcarrier signal-to-noise ratio data; S22, error tolerance bit dynamic configuration: input the subcarrier signal-to-noise ratio data, for subcarriers with high signal-to-noise ratio, the error bit tolerance is at least relaxed to two bits; for subcarriers with low signal-to-noise ratio, the error bit tolerance is kept at 1 bit, and subcarrier error tolerance bit configuration parameters are obtained; S23, candidate QAM point set construction: input the synchronized WiFi signal and each subcarrier error tolerance bit configuration parameter, calculate the candidate QAM point set according to the error tolerance bit threshold, and define the candidate QAM point set with a difference of 1 bit as wherein w is the QAM point of the synchronized WiFi signal, HD represents the Hamming distance, and the candidate QAM point set corresponding to each subcarrier is obtained. S24, ZigBee amplitude and phase optimization: input the synchronized ZigBee signal and the candidate QAM point set, keep the phase shift between adjacent two ZigBee sampling data unchanged, adjust the amplitude and phase of the ZigBee signal segment by segment to make it close to the candidate QAM point set, and obtain the optimized ZigBee signal mapping point; S25, optimal mixed QAM point determination: input candidate QAM point set and the optimized ZigBee signal mapping point , wherein, is a candidate quadrature amplitude modulation constellation point, and the Euclidean distance formula , the Euclidean distance between each candidate QAM point and the ZigBee signal mapping point is calculated, the point with the smallest distance is selected as the QAM point of the final mixed signal, and a mixed baseband signal is obtained; wherein, M is the dimension of the constellation point, is a candidate QAM point , the first dimensional coordinate of is the first dimensional coordinate of the ZigBee signal mapping point z.

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