CN112152664A - An anti-multipath and anti-jamming signal transmission method based on time division multiple access - Google Patents

Abstract

The invention discloses a time division multiple access-based anti-multipath anti-interference signal sending method, and relates to the technical field of radio transmission and communication. The method comprises the steps of firstly generating a frequency hopping field according to frequency hopping frequency sequence information, adding information source data behind the frequency hopping field, then sequentially carrying out channel coding, interweaving, modulation, segmentation, pilot frequency insertion, scrambling, OFDM symbol mapping and then inserting a synchronization field to obtain a synchronization segment burst signal; then, carrying out channel coding, interleaving, modulation, segmentation, pilot frequency insertion, scrambling, OFDM symbol mapping and frequency hopping guard interval insertion on subsequent information source data to obtain a data segment burst signal; then, inserting a demodulation guard interval between the burst signal of the synchronization segment and the burst signal of the data segment to obtain a time slot signal; finally, the time slot signal is changed into a frequency hopping signal through the radio frequency channel module and is sent out through the antenna. The method has reliable and stable performance and can meet the requirements of the field of wireless communication.

Description

An anti-multipath and anti-jamming signal transmission method based on time division multiple access

technical field

The present invention relates to the technical field of radio transmission and communication, in particular to a method for sending anti-multipath and anti-jamming signals based on time division multiple access.

Background technique

The traditional continuous wave transmission system supports a small number of users, and due to the continuous transmission of radio waves, the concealment ability is weak. The burst transmission technology effectively improves the anti-interception and anti-interference capabilities of the communication system by shortening the residence time of the signal in space. On this basis, the system allocates different time slots to each node, and each node in the network transmits signals in its own working time slot. This system has the characteristics of high channel utilization and low equipment cost.

In addition, the OFDM communication system has the advantages of anti-multipath interference, and the frequency hopping communication system has the advantages of anti-interference and anti-interception. By combining burst OFDM technology and frequency hopping technology, an effective anti-multipath, anti-interception and anti-interference transmission mode will be provided for communication between multiple nodes. However, such a communication transmission method is still lacking in the current prior art.

SUMMARY OF THE INVENTION

In view of this, the present invention provides an anti-multipath anti-interference signal receiving method based on time division multiple access, which has reliable and stable performance and can meet the needs of the wireless communication field.

In order to achieve the above object, the technical scheme provided by the present invention is:

A method for transmitting anti-multipath anti-interference signals based on time division multiple access, comprising the following steps:

Step 1: add CRC check information after the frequency hopping frequency sequence information output by the frequency hopping frequency information controller to generate a frequency hopping field;

Step 2: perform channel coding on the frequency hopping field, add source data behind, and obtain front data after merging; wherein, the length of the data output by the source is determined by the framing controller;

Step 3: Channel coding and interleaving are performed on the front data in turn to obtain a front interleaved signal;

Step 4: modulate the front interleaved signal to obtain the front modulated signal;

Step 5: segment the front modulated data, the length of each segment is L _seg , and each segment is called segment modulation data, and a total of Front _seg segment modulation data is obtained, which is called the front segment modulation data sequence;

Step 6: Perform a pilot insertion operation on each segment modulated data in step 5 to obtain the front frequency domain symbol, and the front segment modulation data sequence obtains Front _seg front frequency domain symbols, which is called the front frequency domain symbol sequence. ;

Step 7: Scrambling the front frequency domain symbol, and then mapping it to the effective position of the OFDM frequency domain symbol, and then performing IFFT inverse fast Fourier transform, the front frequency domain symbol sequence A total of Front _seg front OFDM time-domain symbols, referred to as the preceding OFDM time-domain symbol sequence;

Step 8: insert a synchronization field in front of the front OFDM time-domain symbol sequence in step 7 to obtain a synchronization segment burst signal;

Step 9: the source continues to output data to obtain rear data; wherein the length of the data output by the source is determined by the framing controller;

Step 10: The rear data is subjected to channel coding and interleaving in turn to obtain a rear interleaved signal;

Step 11: modulate the rear interleaved signal to obtain a rear modulated signal;

Step 12: Segment the back modulated data, the length of each segment is L _seg , each segment is called segment modulated data, and a total of Back _seg segment modulated data is obtained, which is called a back modulated data sequence ;

Step 13: Perform a pilot insertion operation on each segment modulated data in Step 12 to obtain a rear frequency domain symbol, and the rear modulation data sequence obtains a total of Back _seg front frequency domain symbols, which are called rear frequency domain symbols. sequence;

Step 14: Scrambling the rear frequency domain symbols, and then mapping them to the effective positions of the OFDM frequency domain symbols, and then performing IFFT inverse fast Fourier transform, the rear frequency domain symbol sequence obtains Back _seg rear OFDM in total time-domain symbols, called the rear OFDM time-domain symbol sequence;

Step 15: According to the residence time of the frequency hopping frequency in the frequency hopping frequency sequence information, sequentially extract the OFDM time domain symbols of the corresponding length from the rear OFDM time domain symbol sequence in step 14, and then insert the OFDM time domain symbols in front of these OFDM time domain symbols. The frequency hopping guard interval forms frequency hopping time domain symbols, and these frequency hopping time domain symbols are called data segment burst signals; among them, the frequency hopping guard interval time requires not less than the frequency agility time of the channel equipment;

Step 16: The framing controller inserts a demodulation guard interval after the synchronization segment burst signal, and then adds a data segment burst signal to obtain a time slot signal; wherein, the demodulation guard interval is not less than the receiving end demodulation synchronization segment burst the time of the signal;

Step 17: The time slot signal undergoes digital-to-analog conversion to obtain an analog burst signal;

Step 18: The radio frequency channel module generates a frequency hopping signal according to the analog burst signal and the frequency hopping frequency sequence information, and transmits it through the antenna; wherein the frequency hopping frequency sequence information is generated by the frequency hopping frequency information controller.

Further, the frequency hopping frequency sequence information in step 1 includes the frequency hopping information of the current time slot and the following time slot, and the frequency hopping information includes the serial number of the frequency hopping frequency and the dwell time of the frequency hopping frequency; wherein, the frequency hopping frequency The frequency information controller is controlled by the synchronization signal of the framing controller.

Further, the length of the front modulation signal in step 4 is L _seg ×Front _seg , and the length of the rear modulation signal in step 11 is L _seg ×Back _seg .

Further, the length of the IFFT inverse fast Fourier transform in step 7 and step 14 is the total number N of sub-carriers, N=2 ⁿ , n is a positive integer; wherein, the effective position does not include the position of the DC sub-carrier, the highest positive Subcarrier position near the frequency, subcarrier position near the lowest negative frequency.

Further, the synchronization field in step 8 is divided into three parts, the first part is a protection field, and its length is greater than the radio frequency AGC establishment time, the second part is M ₁ repeated fields with a length of L ₁ , and the third part is is a specific sequence of length L ₂ ; M ₁ , L ₁ , and L ₂ are positive integers; wherein, the frequency hopping frequency remains unchanged during the duration of the burst signal of the sync segment.

Further, in step 16, the parameters of the time slot and the time frame are controlled by the framing controller, which specifically includes the length of the time slot, the length of the guard interval of the time slot, and the length of the time frame.

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts the combination of OFDM and frequency hopping to transmit data, and has the characteristics of anti-interference, anti-multipath and anti-interception.

2. The present invention is a burst transmission mode, which can provide a network mode of time division multiple access for multiple nodes.

3. The present invention can flexibly configure the length of burst data and provide a flexible networking mode to transmit data.

Description of drawings

FIG. 1 is a structural diagram of a transmitter in an embodiment of the present invention.

FIG. 2 is a structural diagram of a time frame and a time slot in an embodiment of the present invention.

FIG. 3 is a capture structure diagram in an embodiment of the present invention.

FIG. 4 is a structural diagram of a receiving end in an embodiment of the present invention.

Detailed ways

1 and 2, a method for transmitting anti-multipath and anti-interference signals based on time division multiple access includes the following steps:

Step 1: Add CRC check information after the frequency hopping frequency sequence information output by the frequency hopping frequency information controller to generate a frequency hopping field; wherein the frequency hopping frequency sequence information includes the frequency hopping information of the current time slot and the following time slots, The frequency information includes the serial number of the frequency hopping frequency and the dwell time of the frequency hopping frequency; wherein the frequency hopping frequency information controller is controlled by the synchronization signal of the framing controller;

Step 2: Channel coding is performed on the frequency hopping field, and the source data is added behind, and the front data is obtained after merging; wherein the data length output by the source is determined by the framing controller;

Step 3: Channel coding and interleaving are performed on the front data in turn to obtain a front interleaved signal;

Step 4: modulate the front interleaved signal to obtain the front modulated signal;

Step 5: Segment the front modulated data, the length of each segment is L _seg , each segment is called segment modulated data, and a total of Front _seg segment modulated data is obtained, which is called the front segment modulated data sequence, The length of the front modulated signal in step 4 is required to be L _seg ×Front _seg ;

Step 6: Perform a pilot insertion operation on each segment modulated data in step 5 to obtain the front frequency domain symbol, and the front segment modulation data sequence obtains Front _seg front frequency domain symbols, which is called the front frequency domain symbol sequence. ;

Step 7: Scrambling the front frequency domain symbol, and then mapping it to the effective position of the OFDM frequency domain symbol, and then performing the IFFT operation, the front frequency domain symbol sequence obtains a total of Front _seg front OFDM time domain symbols, called is the first OFDM time-domain symbol sequence; the length of the IFFT operation is the total number of sub-carriers N, N=2 ⁿ , n is a positive integer; the effective position does not include the DC sub-carrier position, the sub-carrier near the highest positive frequency position, subcarrier position near the lowest negative frequency;

Step 8: Insert a synchronization field in front of the front OFDM time-domain symbol sequence in step 7 to obtain a synchronization segment burst signal; further, the synchronization field is divided into three parts, the first part is a protection field, and its length is greater than Radio AGC setup time, the second part is M ₁ repeated fields of length L ₁ , the third part is a specific sequence of length L ₂ ; M ₁ , L ₁ , L ₂ are positive integers; The frequency hopping frequency remains unchanged during the signaling duration;

Step 9: the source continues to output data to obtain rear data; wherein the length of the data output by the source is determined by the framing controller;

Step 10: The rear data is subjected to channel coding and interleaving in turn to obtain a rear interleaved signal;

Step 11: modulate the rear interleaved signal to obtain a rear modulated signal;

Step 12: Segment the back modulated data, the length of each segment is L _seg , and each segment is called segment modulated data, and a total of Back _seg segment modulated data is obtained, which is called a back modulated data sequence ; The length of the back modulation signal in step 11 is required to be L _seg ×Back _seg ;

Step 13: Perform a pilot insertion operation on each segment modulated data in step 12 to obtain a rear frequency domain symbol, and the rear modulation data sequence obtains a total of Back _seg front frequency domain symbols, which are called rear frequency domain symbols. sequence;

Step 14: Scrambling the rear frequency domain symbols, and then mapping them to the effective positions of the OFDM frequency domain symbols, and then performing IFFT operation, the rear frequency domain symbol sequence obtains Back _seg rear OFDM time domain symbols in total, called is the rear OFDM time-domain symbol sequence; the length of the IFFT operation is the total number of sub-carriers N, N=2 ⁿ , n is a positive integer; the effective position does not include the DC sub-carrier position, the sub-carrier near the highest positive frequency position, subcarrier position near the lowest negative frequency;

Step 15: According to the residence time of the frequency hopping frequency in the frequency hopping frequency sequence information, sequentially extract the OFDM time domain symbols of the corresponding length from the rear OFDM time domain symbol sequence in step 14, and then insert the OFDM time domain symbols in front of these OFDM time domain symbols. The frequency hopping guard interval forms frequency hopping time domain symbols, and these frequency hopping time domain symbols are called data segment burst signals; the frequency hopping guard interval time requires not less than the frequency agility time of the channel equipment;

For example, if the frequency hopping frequency dwell time sequence of the current time slot is (k ₁ , k ₂ , k ₃ ,...), the first k ₁ OFDM time-domain symbols are extracted from the latter OFDM time-domain symbol sequence respectively symbol, insert the frequency hopping guard interval before and after the k ₁ OFDM time domain symbols to form the first frequency hopping time domain symbol; then extract the subsequent k ₂ OFDM time domain symbols, when these k ₂ OFDM symbols A frequency hopping guard interval is inserted before and after the domain symbol to form a second frequency hopping time domain symbol, and so on until the current time slot is completed. The parameters k ₁ , k ₂ , and k ₃ are positive integers.

Step 16: The framing controller inserts a demodulation guard interval after the synchronization segment burst signal, and then adds a data segment burst signal to obtain a time slot signal; wherein the demodulation guard interval is not less than the receiving end demodulates the synchronization segment burst signal The framing controller controls the parameters of the time slot and the time frame, including the length of the time slot, the length of the guard interval of the time slot, and the length of the time frame.

Step 17: The time slot signal undergoes DA conversion to obtain an analog burst signal;

Step 18: The radio frequency channel module generates a frequency hopping signal according to the analog burst signal and the frequency hopping frequency sequence information, and transmits it through the antenna; wherein the frequency hopping frequency sequence information is generated by the frequency hopping frequency information controller.

3 and 4, corresponding to the above-mentioned sending method, the receiving method adopted by the receiving end is as follows:

Step 1: Radio waves pass through the antenna to generate RF analog signals;

Step 2: the radio frequency channel module generates an intermediate frequency analog signal according to the frequency hopping frequency sequence information and the radio frequency analog signal;

Among them, the frequency hopping frequency sequence information comes from the data analysis module or the capture module; only when the data analysis module does not output the frequency hopping frequency sequence information, the RF channel module generates the intermediate frequency analog signal according to the frequency hopping frequency sequence information and the RF analog signal of the capture module. ;The capture module outputs the frequency hopping frequency sequence information as the initial value used by the RF channel module;

Step 3: After the intermediate frequency analog signal is converted by A/D, a digital signal is generated;

Step 4: The capture module outputs the frequency hopping frequency sequence information to the radio frequency channel module, captures the digital signal in step 3, and outputs the estimated value of frequency offset and time position; the specific method is:

(1) The acquisition module outputs the frequency hopping frequency sequence information as the initial value used by the radio frequency channel module;

(2) Carry out delay and conjugate operations on the digital signal to obtain a delayed conjugate signal; wherein the delay length is related to the length of the second partial repetition field of the synchronization segment, and is a positive integer multiple of L ₁ ;

(3) The delayed conjugate signal is correlated with the digital signal to obtain the correlation signal corr(n) in the first capture stage:

Wherein, r(n) is a digital signal, N ₁ is a positive integer, M ₁ is the number of repetitions of the repetition field, and L ₁ is the length of the repetition field;

(4) The relevant signals in the first capture stage are subjected to sliding accumulation to obtain the sliding accumulation signal slide_acc(n):

Among them, accLen is a positive integer, indicating the sliding accumulation length;

(5) Find the peak value of the sliding accumulation signal, and output the first timing position first_pos and the fractional frequency offset k _δ :

first_pos=arg max|slide_acc(n)|+1-accLen

Wherein, N is the number of OFDM subcarriers, and PL ₁ and PL ₂ are positive integers;

(6) According to the decimal frequency offset and the first timing position, correct the digital signal time offset and decimal frequency offset, and obtain the digital signal after initial correction;

(7) from the digital signal after the initial correction, the specific sequence of length L ₂ is extracted and output; wherein, the specific sequence of length L ₂ is the third part in the synchronization segment;

(8) Perform FFT transformation on a specific sequence, and then output it to P+1 branches respectively, the p-th branch is cyclically shifted by -P/2+p, where P is an even number:

Among them, branch _p (k) is the frequency domain signal of the p-th branch, and spa_seq(n) represents the time domain form of a specific sequence;

(9) Each branch is correlated with the local specific sequence to obtain the correlation sequence I _p (k) in the secondary capture stage:

I _p (k)=branch _p (k)·local(k),k=0,1,...,N-1

Among them, local(k) is a local specific sequence;

(10) Perform the autocorrelation operation on the correlation sequence in the secondary capture stage to obtain the autocorrelation value:

Among them, R(p, delay) is the autocorrelation value of the p-th branch, and delay is the time difference of the autocorrelation, which is a positive integer;

(11) Compare the autocorrelation amplitude values of the P+1 branches, and select the branch with the largest amplitude value. If the amplitude value is greater than the threshold value, the integer frequency offset value k _int and the secondary timing position second_pos are obtained:

k _int =argmax|R(p,delay)|,p=0,1,...P

Among them, the threshold value is related to the digital signal amplitude;

(12) According to the first timing position, the fractional frequency offset, the integer frequency offset value, and the second timing position, obtain the estimated values of the frequency offset and the time position, and output them;

Step 5: According to the estimated values of frequency offset and time position output in step 4, perform frequency offset correction and time offset correction on the digital signal, and output the corrected digital signal;

Step 6: The cyclic prefix removal operation is performed on the corrected digital signal, and the OFDM time domain symbol is output;

Step 7: FFT operation is performed on the OFDM time-domain symbols, and the OFDM frequency-domain symbols are output;

Step 8: The left and right guard subcarriers are removed from the OFDM frequency domain symbol to obtain an OFDM frequency domain sequence;

Step 9: perform a descrambling operation on the OFDM frequency domain sequence to obtain an unscrambled frequency domain sequence;

Step 10: Perform channel estimation on the unscrambled frequency domain sequence to obtain a channel information vector; wherein, the channel estimation algorithm adopts the least squares algorithm or the least mean square error estimation algorithm:

表示小二乘法算法估计的信道信息向量，

表示最小均方误差估计算法估计的信道信息向量；X表示导频信号列向量，Y表示接收到的导频信号列向量，R_HH＝E(HH^H)表示信道自相关矩阵，

表示噪声能量；in,

represents the channel information vector estimated by the little square algorithm,

represents the channel information vector estimated by the minimum mean square error estimation algorithm; X represents the pilot signal column vector, Y represents the received pilot signal column vector, R _HH =E(HH ^H ) represents the channel autocorrelation matrix,

represents the noise energy;

Step 11: Perform channel equalization and demodulation on the unscrambled frequency domain sequence according to the channel information vector to obtain an equalized demodulated signal;

Step 12: The demodulated signal is deinterleaved to obtain a deinterleaved signal;

Step 13: perform channel decoding operation on the deinterleaved signal to obtain received data;

Step 14: the data analysis module processes the received data, determines the type of the received data, and outputs the source data and frequency hopping frequency sequence information;

(1) If the received data is the front data, CRC check is performed;

If the CRC check is wrong, the front data and the back data will be discarded; if the CRC check is correct, the frequency hopping frequency sequence information will be output to the radio frequency channel module, and the source data will be output at the same time; wherein, the parsed frequency hopping frequency sequence information contains the current Frequency hopping information of the time slot and the following time slot, the frequency hopping information includes the serial number of the frequency hopping frequency and the dwell time of the frequency hopping frequency;

(2) If the received data is rear data, the data is directly output.

In a word, in this transmission method, the frequency hopping field is first generated according to the frequency hopping frequency sequence information, and after adding the source data, channel coding, interleaving, modulation, segmentation, pilot frequency insertion, scrambling, OFDM symbol mapping and then synchronization insertion are performed in sequence. Then, the subsequent source data is subjected to channel coding, interleaving, modulation, segmentation, pilot frequency insertion, scrambling, OFDM symbol mapping, and frequency hopping guard interval insertion to obtain a data segment burst signal; Then, a demodulation guard interval is inserted between the synchronization segment burst signal and the data segment burst signal to obtain a time slot signal; finally, the time slot signal is converted into a frequency hopping signal through the radio frequency channel module and sent out through the antenna. The method of the invention has reliable and stable performance, and can meet the needs of the wireless communication field.

Claims (6)

1. an anti-multipath anti-interference signal transmission method based on time division multiple access, is characterized in that, comprises the following steps: Step 1: add CRC check information after the frequency hopping frequency sequence information output by the frequency hopping frequency information controller to generate a frequency hopping field; Step 2: perform channel coding on the frequency hopping field, add source data behind, and obtain front data after merging; wherein, the length of the data output by the source is determined by the framing controller; Step 3: Channel coding and interleaving are performed on the front data in turn to obtain a front interleaved signal; Step 4: modulate the front interleaved signal to obtain the front modulated signal; Step 5: segment the front modulated data, the length of each segment is L _seg , and each segment is called segment modulation data, and a total of Front _seg segment modulation data is obtained, which is called the front segment modulation data sequence; Step 6: Perform a pilot insertion operation on each segment modulated data in step 5 to obtain the front frequency domain symbol, and the front segment modulation data sequence obtains Front _seg front frequency domain symbols, which is called the front frequency domain symbol sequence. ; Step 7: Scrambling the front frequency domain symbol, and then mapping it to the effective position of the OFDM frequency domain symbol, and then performing IFFT inverse fast Fourier transform, the front frequency domain symbol sequence A total of Front _seg front OFDM time-domain symbols, referred to as the preceding OFDM time-domain symbol sequence; Step 8: insert a synchronization field in front of the front OFDM time-domain symbol sequence in step 7 to obtain a synchronization segment burst signal; Step 9: the source continues to output data to obtain rear data; wherein the length of the data output by the source is determined by the framing controller; Step 10: The rear data is subjected to channel coding and interleaving in turn to obtain a rear interleaved signal; Step 11: modulate the rear interleaved signal to obtain a rear modulated signal; Step 12: Segment the back modulated data, the length of each segment is L _seg , and each segment is called segment modulated data, and a total of Back _seg segment modulated data is obtained, which is called a back modulated data sequence ; Step 13: Perform a pilot insertion operation on each segment modulated data in Step 12 to obtain a rear frequency domain symbol, and the rear modulation data sequence obtains a total of Back _seg front frequency domain symbols, which are called rear frequency domain symbols. sequence; Step 14: Scrambling the rear frequency domain symbols, and then mapping them to the effective positions of the OFDM frequency domain symbols, and then performing IFFT inverse fast Fourier transform, the rear frequency domain symbol sequence obtains Back _seg rear OFDM in total time-domain symbols, called the rear OFDM time-domain symbol sequence; Step 15: According to the residence time of the frequency hopping frequency in the frequency hopping frequency sequence information, sequentially extract the OFDM time domain symbols of the corresponding length from the rear OFDM time domain symbol sequence in step 14, and then insert the OFDM time domain symbols in front of these OFDM time domain symbols. The frequency hopping guard interval forms frequency hopping time domain symbols, and these frequency hopping time domain symbols are called data segment burst signals; among them, the frequency hopping guard interval time requires not less than the frequency agility time of the channel equipment; Step 16: The framing controller inserts a demodulation guard interval after the synchronization segment burst signal, and then adds a data segment burst signal to obtain a time slot signal; wherein, the demodulation guard interval is not less than the receiving end demodulation synchronization segment burst the time of the signal; Step 17: The time slot signal undergoes digital-to-analog conversion to obtain an analog burst signal; Step 18: The radio frequency channel module generates a frequency hopping signal according to the analog burst signal and the frequency hopping frequency sequence information, and transmits it through the antenna; wherein the frequency hopping frequency sequence information is generated by the frequency hopping frequency information controller. 2. a kind of anti-multipath anti-interference signal transmission method based on time division multiple access according to claim 1, is characterized in that, the frequency hopping frequency sequence information in step 1 comprises the frequency hopping of current time slot and back time slot The frequency hopping information includes the serial number of the frequency hopping frequency and the dwell time of the frequency hopping frequency; wherein, the frequency hopping frequency information controller is controlled by the synchronization signal of the framing controller. 3. a kind of anti-multipath anti-jamming signal transmission method based on time division multiple access according to claim 1, is characterized in that, the length of the front modulated signal in step 4 is L _seg ×Front _seg , in step 11. The length of the back modulated signal is L _seg ×Back _seg . 4. a kind of anti-multipath anti-interference signal transmission method based on time division multiple access according to claim 1, is characterized in that, the length of the IFFT inverse fast Fourier transform in step 7 and step 14 is the length of subcarrier. The total number N, N=2 ⁿ , where n is a positive integer; wherein, the effective position does not include the DC sub-carrier position, the sub-carrier position near the highest positive frequency, and the sub-carrier position near the lowest negative frequency. 5. a kind of anti-multipath anti-interference signal transmission method based on time division multiple access according to claim 1, is characterized in that, the synchronization field in step 8 is divided into three parts, the first part is the protection field, which The length is greater than the radio AGC setup time, the second part is M ₁ repeated fields of length L ₁ , and the third part is a specific sequence of length L ₂ ; M ₁ , L ₁ , and L ₂ are positive integers; The hopping frequency remains unchanged for the duration of the sync segment burst signal. 6. a kind of anti-multipath anti-interference signal transmission method based on time division multiple access according to claim 1, is characterized in that, in step 16, the parameter of time slot and time frame is controlled by framing controller, specifically comprises time slot length, slot guard interval length, time frame length.

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