Multi-carrier interference avoidance frequency selection method based on channelization

Abstract

The invention discloses a multi-carrier interference avoidance frequency selection method based on channelization, and belongs to the technical field of wireless communication. Based on the frequency domain characteristic of a multi-carrier signal, a channelization method is utilized to divide a working frequency band into a plurality of channels, sampling analysis is carried out on an electromagnetic environment in combination with a zero intermediate frequency receiver, communication is carried out by determining the energy value of each channel and selecting a subcarrier frequency point with minimum interference, and when interference is encountered in the communication process, the communication efficiency is improved. And dynamically adjusting the frequency selection method according to the feedback of the receiver. According to the invention, by reducing the complexity of frequency switching and the number of iterations of frequency selection, the anti-interference capability of a communication system can be improved, and the spectrum utilization efficiency and the communication reliability can be improved.

Description

Technical Field

[0001] The invention relates to a multi-carrier interference avoidance frequency selection method based on channelization, and belongs to the technical field of wireless communication. Background Art

[0002] The rapid development of mobile communication technology and the popularization of smart terminals have promoted the widespread application of multimedia devices. The efficient use of spectrum resources has become a key issue in the field of wireless communications. Multi-carrier communication technology occupies an important position in wireless communication systems due to its high spectrum efficiency, easy equalization and strong resistance to multipath interference.

[0003] Multi-carrier signals occupy multiple frequency bands in the frequency domain, and the interval between adjacent frequency bands is an integer multiple of the bandwidth value, which makes them more susceptible to interference. The interference of multi-carrier signals not only affects the communication quality, but also causes communication interruption and information loss. The traditional interference avoidance method has the problems of high complexity and large amount of calculation when applied to multi-carrier signals, which makes it difficult to meet the actual application requirements. In order to improve the reliability and stability of the communication system, how to effectively avoid interference has become an urgent problem to be solved. Summary of the invention

[0004] In order to solve the problems existing in the application of traditional interference avoidance methods in multi-carrier signals, the purpose of the present invention is to provide a multi-carrier interference avoidance frequency selection method based on channelization, which performs channelization processing on the working frequency band of the multi-carrier signal, evenly divides the entire frequency band into a number of channels, combines a zero intermediate frequency receiver to sample the electromagnetic environment signal, and selects the sub-carrier frequency with the least interference by calculating the energy of each channel to form an optimal frequency set, thereby realizing the effective selection of the optimal sub-carrier frequency in a complex electromagnetic environment and improving the performance and reliability of the multi-carrier communication system.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A multi-carrier interference avoidance frequency selection method based on channelization, by determining the working frequency band and center frequency of the multi-carrier signal, combining the subcarrier bandwidth and the minimum adjacent subcarrier spacing, determining the number of channels required for channelization, sampling the electromagnetic environment through a zero intermediate frequency receiver, and evenly dividing the entire frequency band into multiple channels, selecting a starting channel and step-by-step determining the alternative subcarrier frequency points, determining the channel energy occupied by the subcarrier corresponding to the alternative subcarrier frequency points through the receiver, and obtaining the optimal subcarrier frequency point set. During the communication process, when interference occurs, the transmitter adjusts the frequency selection strategy according to the information fed back by the receiver, and selects the subcarrier frequency point with the least interference for communication, which specifically includes the following steps:

[0007] Step 1: Determine the communication parameters;

[0008] Determine the operating frequency band [f1, f2] of the communication system, the center frequency point f0 of the operating frequency band, the subcarrier bandwidth B, the minimum adjacent subcarrier spacing BI, and the number of channels K;

[0009] The channel bandwidth RBW is shown in formula (1):

[0010] RBW=(f2--f1) / K (1)

[0011] The number of channels K satisfies the subcarrier bandwidth B and the minimum adjacent subcarrier spacing BI is an integer multiple of the channel bandwidth RBW, as shown in equations (2) and (3):

[0012] B=p·RBW (2)

[0013] BI=q·RBW (3)

[0014] Wherein, p is the ratio of the subcarrier bandwidth B to the channel bandwidth RBW, and q is the ratio of the minimum adjacent subcarrier spacing BI to the channel bandwidth RBW;

[0015] Step 2: Sample the electromagnetic environment at zero intermediate frequency and perform channelization on the sampled signal spectrum;

[0016] The electromagnetic environment is sampled by a zero intermediate frequency receiver, and the spectrum of the sampled signal is channelized to evenly divide the entire frequency band [f1, f2] into K channels. The channels are numbered k from low frequency to high frequency, k = 0, 1, ..., K-1; the initial channel number of the frequency selection channel is i = 0;

[0017] Step 3: Determine the candidate subcarrier frequency points;

[0018] Extracting power spectrum density features of the power spectrum density data, and determining candidate subcarrier frequency points according to the extracted power spectrum density features;

[0019] The i-th channel is taken as the starting channel, the i+p / 2-1-th channel is taken as the first candidate subcarrier frequency point, and the remaining subcarrier frequencies available for selection are found with q as the channel step, a total of mi, as shown in formula (4):

[0020]

[0021] Step 4: Determine the channel energy occupied by the subcarrier and the sum of the minimum subcarrier channel energy;

[0022] Based on the candidate subcarrier frequency points determined in step 3, determine the sum of channel energies occupied by each subcarrier;

[0023] Determine the channel energy occupied by the subcarriers corresponding to the mi frequency points, sort the mi candidate subcarrier channel energies in ascending order, select the first N subcarrier frequency points of the sorting result, and the sum Hi of the channel energies of the N selected subcarriers is the smallest at this time, and obtain the channel Ci corresponding to the N subcarrier frequency points at this time, as shown in formula (5):

[0024] Ci={ki, 1, ki, 2,..., ki, N} (5)

[0025] Wherein, N is the number of subcarriers of the multicarrier signal, and ki is the subcarrier frequency;

[0026] Step 5: Determine the minimum value of the sum of subcarrier channel energies and the corresponding channel;

[0027] Traverse all channels as the starting channel, determine the sum of the corresponding subcarrier channel energy Hi, find the minimum value in the Hi set, and the channel C corresponding to the N subcarrier frequency points at this time final , as shown in formula (6):

[0028] C final i={k final i,1,k final i,2,…,k final i,N} (6)

[0029] Among them, k final The subcarrier frequency corresponding to when i is the minimum value in the Hi set;

[0030] Step 6: Determine the frequency selection for avoiding multi-carrier interference;

[0031] Determine the subcarrier frequency value according to the channel corresponding to the subcarrier frequency in step 5, that is, the frequency selection for avoiding multicarrier interference based on channelization;

[0032] The method also includes step seven, in which the multi-carrier transmitter sends a multi-carrier signal according to the corresponding frequency point according to the sub-carrier frequency point value obtained in step six. In a given spectrum environment, the multi-carrier transmitter can avoid interference in the electromagnetic environment, reduce the impact of interference on communication, and improve the performance and reliability of the multi-carrier communication system.

[0033] Beneficial effects:

[0034] 1. A multi-carrier interference avoidance frequency selection method based on channelization of the present invention divides the frequency band of the multi-carrier signal by using a channelization method, combines a zero intermediate frequency receiver to perform real-time sampling of the electromagnetic environment, and realizes effective frequency selection through a smaller number of iterations, thereby solving the problems of low spectrum utilization and high implementation complexity in traditional multi-carrier interference avoidance strategies, and improving the stability of communication and spectrum utilization efficiency.

[0035] 2. The present invention provides a channelized multi-carrier interference avoidance frequency selection method, which determines the energy value of each channel, selects the subcarrier frequency with the least interference for communication, and timely adjusts the frequency selection method when interference occurs. While maintaining communication reliability, it reduces the complexity and time consumption of frequency switching, thereby improving the anti-interference ability and overall performance of communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of a channelized multi-carrier interference avoidance frequency selection method of the present invention;

[0037] Figure 2 A spectrum sensing diagram based on channelization in an embodiment;

[0038] Figure 3 This is a frequency selection diagram for avoiding multi-carrier interference based on channelization in an embodiment. DETAILED DESCRIPTION

[0039] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0040] Embodiment 1:

[0041] In a terrestrial multi-carrier communication system, affected by other service signals in the same frequency band on the ground, the transmitter uses a channelized method to perform spectrum sensing and selects appropriate subcarrier frequencies to transmit multi-carrier signals. A multi-carrier interference avoidance frequency selection method based on channelization of the present invention is applied, such as Figure 1 As shown, the following steps are included:

[0042] Step 1: Determine the communication parameters;

[0043] Determine the working frequency band [f1, f2], the center frequency point f0 of the working frequency band, the subcarrier bandwidth B, the minimum adjacent subcarrier spacing BI, and the number of channels K;

[0044] In the embodiment, the working frequency band is determined to be [f01, f02] = [1872 MHz, 2128 MHz], the center frequency of the working frequency band is f0 = 2 GHz, the subcarrier bandwidth B0 = 4 MHz, the minimum adjacent subcarrier interval BI0 = 4 MHz, and the working frequency band [f01, f02] is divided into K = 8192 channels;

[0045] The channel bandwidth RBW is shown in formula (1):

[0046] RBW=(f2-f1) / K (1)

[0047] The number of channels K satisfies the subcarrier bandwidth B and the minimum adjacent subcarrier spacing BI is an integer multiple of the channel bandwidth RBW, as shown in equations (2) and (3):

[0048] B=p·RBW (2)

[0049] BI=q·RBW (3)

[0050] Wherein, p is the ratio of the subcarrier bandwidth B to the channel bandwidth RBW, and q is the ratio of the minimum adjacent subcarrier spacing BI to the channel bandwidth RBW;

[0051] In the embodiment, the number of channels K=8192, the channel bandwidth RBW=31.25kHz, p=128, q=128;

[0052] Step 2: Sample the electromagnetic environment at zero intermediate frequency and perform channelization processing on the sampled signal;

[0053] Collect time domain data signals from sensors and data acquisition equipment. The time domain data signals collected in the electromagnetic environment contain noise and interference. Preprocess the time domain data signals to remove DC components, remove low-frequency drift and high-frequency noise through bandpass filtering, and apply window functions to reduce spectrum leakage. Convert the time domain data signals to the frequency domain through fast Fourier transform, determine the power spectral density of the frequency domain data signals, and analyze the frequency components and energy distribution of the frequency domain data signals.

[0054] Channelize the sampled signal and evenly divide the entire frequency band [1872MHz, 2128MHz] into 8192 channels. The channels are numbered k from low frequency to high frequency, k=0, 1, ..., K-1, and the initial channel number of the frequency selection channel is i=0;

[0055] The results of channelized spectrum sensing are as follows: Figure 2 As shown, the yellow curve represents the spectrum result, the Y-axis represents the power, and the higher the peak value, the greater the interference;

[0056] Step 3: Determine the candidate subcarrier frequency points;

[0057] Extracting power spectrum density features of the power spectrum density data, and determining candidate subcarrier frequency points according to the extracted power spectrum density features;

[0058] Take the lth channel as the starting channel, the i+p / 2-1th channel as the first candidate subcarrier frequency point, and use q as the channel step to find the remaining subcarrier frequencies that can be selected, a total of mi, as shown in formula (4):

[0059]

[0060] Step 4: Determine the channel energy occupied by the subcarrier and the sum of the channel energies of each subcarrier;

[0061] Based on the candidate subcarrier frequency points determined in step 3, determine the sum of channel energies occupied by each subcarrier;

[0062] Determine the channel energy occupied by the subcarriers corresponding to the mi frequency points, sort the mi candidate subcarrier channel energies in ascending order, select the first 8 subcarrier frequency points of the sorting result, and the sum Hi of the 8 subcarrier channel energies selected at this time is the smallest, and obtain the channel Ci corresponding to the 8 subcarrier frequency points at this time, as shown in formula (5):

[0063] Ci={-64MHz, -60MHz, -56MHz, -52MHz, -48MHz, -44MHz, -40MHz, -36MHz} (5)

[0064] Step 5: Determine the minimum value of the sum of subcarrier channel energies and the corresponding channel;

[0065] Traverse all channels as the starting channel, determine the sum of the corresponding subcarrier channel energy Hi, find the minimum value in the Hi set, and the channel C corresponding to the 8 subcarrier frequency points at this time final , as shown in formula (6):

[0066] C final ={-60MHz,--50MHz,-46MHz,-16MHz,-12MHz,20MHz,24MHz,40MHz} (6)

[0067] Step 6: Determine the frequency selection for avoiding multi-carrier interference;

[0068] Determine the subcarrier frequency value according to the channel corresponding to the subcarrier frequency in step 5, that is, the frequency selection for avoiding multicarrier interference based on channelization;

[0069] In the embodiment, the multi-carrier interference avoidance frequency selection result is as follows: Figure 3 As shown, the red box represents the alternative frequency, the width of the red box represents the bandwidth of the signal, and the alternative frequency in the red box is staggered with the interference frequency in the yellow box, indicating that the result of the frequency selection can avoid large interference in the signal;

[0070] The method also includes step seven, in which the multi-carrier transmitter sends a multi-carrier signal according to the corresponding frequency point according to the sub-carrier frequency point value obtained in step six. In a given spectrum environment, the multi-carrier transmitter can avoid interference in the electromagnetic environment, reduce the impact of interference on communication, and improve the performance and reliability of the multi-carrier communication system.

[0071] Embodiments A multi-carrier interference avoidance frequency selection method based on channelization of the present invention is applied. The frequency band of the multi-carrier signal is divided into 8192 segments by using a channelization algorithm. The electromagnetic environment is sampled in real time by combining a zero intermediate frequency receiver. The frequency selection is realized by a small number of iterations, and the time complexity of the system is reduced to O(n2). The problems of low spectrum utilization and high implementation complexity in the traditional multi-carrier interference avoidance strategy are solved. The selected C final ={-60MHz,--50MHz,-46MHz,-16MHz,-12MHz,20MHz,24MHz,40MHz} frequency point can avoid the position of the transmission signal in the channel, effectively improving the stability of communication and the efficiency of spectrum utilization; by determining the energy value of each channel, selecting the sorted minimum energy value sequence Hi ={-42.45dBm,-43.15dBm,-48.56dBm,-47.12dBm,-44.54dBm,-43.11dBm,-42.29dBm,-49.77dBm}, select the subcarrier frequency point with the smallest interference energy for communication, that is, select the frequency point C final ={-60MHz,--50MHz,-46MHz,-16MHz,-12MHz,20MHz,24MHz,40MHz}, and adjust the frequency selection method in time when interference occurs. While maintaining communication reliability, it reduces the complexity and time consumption of frequency switching, makes the system signal-to-noise ratio fall back to less than 3dB, and improves the overall communication performance of the system.

[0072] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-carrier interference avoidance frequency selection method based on channelization, characterized in that: By determining the working frequency band and center frequency of the multi-carrier signal, combining the subcarrier bandwidth and the minimum adjacent subcarrier spacing, the number of channels required for channelization is determined, the electromagnetic environment is sampled through a zero intermediate frequency receiver, and the entire frequency band is evenly divided into multiple channels, the starting channel is selected and the alternative subcarrier frequency points are determined step by step, and the channel energy occupied by the subcarrier corresponding to the alternative subcarrier frequency point is determined through the receiver to obtain the optimal subcarrier frequency point set. During the communication process, when interference occurs, the transmitter adjusts the frequency selection strategy according to the information fed back by the receiver, and selects the subcarrier frequency point with the least interference for communication. Specifically, the following steps are included: Step 1: Determine the communication parameters; Determine the operating frequency band [f1, f2] of the communication system, the center frequency point f0 of the operating frequency band, the subcarrier bandwidth B, the minimum adjacent subcarrier spacing BI, and the number of channels K; The channel bandwidth RBW is shown in formula (1): RBW=(f2-f1) / K (1) The number of channels K satisfies the subcarrier bandwidth B and the minimum adjacent subcarrier spacing BI is an integer multiple of the channel bandwidth RBW, as shown in equations (2) and (3): B=p·RBW (2) BI=q·RBW (3) Wherein, p is the ratio of the subcarrier bandwidth B to the channel bandwidth RBW, and q is the ratio of the minimum adjacent subcarrier spacing BI to the channel bandwidth RBW; Step 2: Sample the electromagnetic environment at zero intermediate frequency and perform channelization on the sampled signal spectrum; The zero intermediate frequency receiver samples the electromagnetic environment and performs channelization on the sampled signal spectrum, dividing the entire frequency band [f1, f2] evenly into K channels. The channels are numbered k from low frequency to high frequency, k = 0, 1, ..., K-1; the initial channel number of the frequency selection channel is i = 0; Step 3: Determine the candidate subcarrier frequency points; Extracting power spectrum density features of the power spectrum density data, and determining candidate subcarrier frequency points according to the extracted power spectrum density features; The i-th channel is taken as the starting channel, the i+p / 2-1-th channel is taken as the first candidate subcarrier frequency point, and the remaining candidate subcarrier frequencies are found with q as the channel step, a total of mi, as shown in formula (4): Step 4: Determine the channel energy occupied by the subcarrier and the sum of the minimum subcarrier channel energy; Based on the candidate subcarrier frequency points determined in step 3, determine the sum of channel energies occupied by each subcarrier; Determine the channel energy occupied by the subcarriers corresponding to the mi frequency points, sort the mi candidate subcarrier channel energies in ascending order, select the first N subcarrier frequency points of the sorting result, and the sum Hi of the channel energies of the N selected subcarriers is the smallest at this time, and obtain the channel Ci corresponding to the N subcarrier frequency points at this time, as shown in formula (5): Ci={ki,1,ki,2,…,ki,N} (5) Wherein, N is the number of subcarriers of the multicarrier signal, and ki is the subcarrier frequency; Step 5: Determine the minimum value of the sum of subcarrier channel energies and the corresponding channel; Traverse all channels as the starting channel, determine the sum of the corresponding subcarrier channel energy Hi, find the minimum value in the Hi set, and the channel C corresponding to the N subcarrier frequency points at this time final , as shown in formula (6): C final i={k final i,1,k final i,2,...,k final i,N} (6) Among them, k final The subcarrier frequency corresponding to when i is the minimum value in the Hi set; Step 6: Determine the frequency selection for avoiding multi-carrier interference; The subcarrier frequency value is determined according to the channel corresponding to the subcarrier frequency in step 5, that is, the multi-carrier interference avoidance frequency selection based on channelization.

2. The method for avoiding frequency selection of multi-carrier interference based on channelization according to claim 1, characterized in that: Step seven, according to the subcarrier frequency value obtained in step six, the multicarrier transmitter sends a multicarrier signal according to the corresponding frequency point, which can avoid interference in the electromagnetic environment, reduce the impact of interference on communication, and improve the performance and reliability of the multicarrier communication system in a given spectrum environment.

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