Large Doppler frequency shift OTFS satellite communication demodulation and analysis method and device

Abstract

The present invention discloses a method and device for demodulating and analyzing large Doppler frequency shift (OTFS) satellite communications, belonging to the field of satellite communications. The device includes a data acquisition unit, an IQ imbalance calculation unit, an amplitude error calculation unit, a continuous phase signal generation unit, a convolution detection frame header determination unit, two guard slot removal units, two receive reference signal acquisition units, a sampling phase error acquisition unit, two theoretical demodulation reference signal generation units, a channel model extraction unit, a Doppler frequency error calculation unit, a Doppler frequency error elimination unit, a phase error calculation unit, a Doppler phase error elimination unit, a channel estimation unit, an interpolation and smoothing unit, a channel error elimination unit, a Wigner transform unit, a symplectic finite Fourier transform unit, a digital modulation and demodulation unit, and an error vector magnitude (EVM) calculation unit. The present invention can achieve high-precision demodulation and analysis of large Doppler frequency shift (OTFS) orthogonal time-frequency-space modulation (6G) satellite communication signals.

Description

Technical Field

[0001] The present invention belongs to the technical field of 6G satellite communications, and in particular relates to a large Doppler frequency shift (OTFS) satellite communication demodulation and analysis method and device. Background Art

[0002] With the development of satellite mobile communication technology, high-speed mobile communication scenarios in complex scattering environments are becoming increasingly diverse, and these communication scenarios will greatly change people's lifestyles in the future. Therefore, under the influence of Doppler spread, it is very important to design high-precision demodulation and analysis of new modulation signals with large Doppler frequency shifts in next-generation satellite mobile communication systems for high-speed mobility scenarios. In recent years, researchers have proposed Orthogonal Time Frequency Space (OTFS) modulation technology. This technology performs resource mapping in the Delay Doppler domain (DD) and, based on the sparsity and stability of the DD domain channel, can achieve higher data transmission reliability under high-speed mobility conditions. However, how to achieve high-precision demodulation and analysis of 6G satellite communication signals with OTFS in the presence of large Doppler frequency shifts in engineering has become a difficult problem in the industry.

[0003] With the advancement and maturity of orthogonal time-frequency spatial modulation signal technology, it is foreseeable that this technology will be widely used in 6G satellite mobile communication systems. In particular, the demodulation and analysis of orthogonal time-frequency spatial modulation signals in the presence of large Doppler shift is of great significance to the research and development of 6G satellite mobile communication technology. It can also be used in the standardization of 6G satellite mobile communication technology, helping to formulate standards and specifications for 6G satellite mobile communication technology; in the research of 6G satellite mobile communication systems and test equipment, helping researchers improve the performance of 6G satellite mobile communication systems; in the simulation and optimization of 6G satellite mobile communication systems, optimizing their design and performance; and in the future commercial deployment of 6G satellite mobile communication systems, helping enterprises and operators deploy 6G satellite mobile communication systems and improve the quality and efficiency of 6G satellite mobile communication services. Therefore, high-precision demodulation and analysis methods and devices for 6G satellite mobile communication's new modulation signals in the presence of large Doppler shift are an important component of the development of 6G satellite mobile communication technology. Summary of the Invention

[0004] The present invention proposes a large Doppler shift (OTFS) satellite communication demodulation and analysis method and device, which can realize the demodulation and analysis of orthogonal time-frequency-space modulation signals, and meet the testing requirements of 6G satellite mobile communication technology research and equipment development.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A large Doppler frequency shift OTFS satellite communication demodulation and analysis method, characterized by comprising the following steps:

[0007] Step 1: Digitize the collected communication signal s(t) and perform IQ demodulation to form the first I-channel data S I (i) The first Q-channel data S Q (i) saving the first I-channel data and the first Q-channel data to a fixed storage space for subsequent analysis;

[0008] S I (i)=s(t)*cos(ω c T s )

[0009] S Q (i)=s(t)*sin(ω c T s )

[0010] Among them, i represents the sequence number of the sampling point, ω c is the carrier angular frequency, T s is the sampling period.

[0011] Step 2: Eliminate the first I-way data S I (i) and the first Q-channel data S Q (i) DC signal, and obtain the second I-way data S′ I (i) The second Q-channel data S′ Q (i)

[0012] S′ I (i) = S I (i)- I >

[0013] S′ Q (i) = S Q (i)- Q >

[0014] in, I > for S I The DC estimate of (i), Q > for S Q (i) DC estimate;

[0015] Then calculate the IQ quadrature imbalance coefficient ε:

[0016]

[0017] Among them, <Δ(S I )> is S′ I (i) the amplitude difference, <Δ(S​​​​Q )> is S′ Q (i) The amplitude difference.

[0018] Step 3: Through the second I-way data S' I (i) The second Q-channel data S′ Q (i) Calculate the amplitude error ε of the communication signal s(t) collected this time A :

[0019]

[0020] Step 4: Generate the first I-way continuous phase signal Y according to the sampling period and symbol rate of the communication signal s(t) I (i) and the first Q-path continuous phase signal Y Q (i)

[0021] Y I (i) = Acos(2πωT)

[0022] Y Q (i) = Asin(2πωT)

[0023] Where A is the continuous phase signal Y I (i) and Y Q (i) is the amplitude, ω is the continuous phase signal Y I (i) and Y Q (i) is the angular frequency, T is the continuous phase signal Y I (i) and Y Q (i) The sampling period.

[0024] Step 5: Using the continuous phase signal Y I (i) Y Q (i) Second I-way data S′ Q (i) Second Q-channel data S′ Q (i) Perform convolution to form the third I-way data S″ I (i) and the third Q-channel data S″ Q (i)

[0025] S″ I (i) = S′ I (i)*Y I (i)

[0026] S″ Q (i) = S′ Q (i)*Y Q (i)

[0027] At this time, detect S″ again I (i) and S″ QPhase θ(i) of (i):

[0028] θ(i)=tan -1 (S″ Q (i) / S″ I (i))

[0029] The phase mutation point is S″ I (i) and S″ Q (i) Data frame header.

[0030] Step 6: Set the CP parameter according to the communication signal s(t) to remove the guard time slot data to form the communication signal S4.

[0031] Step 7: Extract the I-channel reference data S′ at the reference signal position in the communication signal S4 according to the setting of the reference signal position and format of the communication signal s(t). 4I (i) and Q-path reference data S′ 4Q (i).

[0032] Step 8: Calculate the I-channel reference data S′ based on the phase continuity characteristics 4I (i) and Q-path reference data S′ 4Q The sampling phase error ε in (i) θ :

[0033]

[0034] in, is the theoretical phase value of the i-th sampling point.

[0035] Step 9: Generate a theoretical demodulation reference I signal based on the modulation format and symbol rate of the communication signal s(t) and Q-channel signal

[0036] Step 10: I-way reference data S′ obtained in step 7 4I (i) and Q-path reference data S′ 4Q (i), and the theoretical demodulation reference I signal obtained in step 9 and Q-channel signal Extract the channel model R for this communication:

[0037]

[0038] in, for The conjugate function of .

[0039] Step 11: Calculate the Doppler frequency error ε based on the communication channel model R f :

[0040]

[0041] Among them, R Q (i) is the Q-path signal of the channel model R, R I (i) is the I-path signal of the channel model R.

[0042] Step 12: According to the Doppler frequency error ε f , generate the Doppler frequency error elimination data H; then eliminate the Doppler frequency error of the communication signal S4 to obtain the main demodulation channel signal S5:

[0043] S5=S4 / H

[0044] Step 13: Set the CP parameter again according to the main demodulation channel signal S5 to remove the guard time slot data to obtain the communication signal S6.

[0045] Step 14: According to the settings of the reference signal position and format of the communication signal S6, the demodulation reference signal S7 at the reference signal position in the communication signal S6 is extracted.

[0046] Step 15: Calculate the sampling phase error ε′ of the demodulation reference signal S7 based on the phase continuity characteristic θ :

[0047]

[0048] Among them, S 7Q (i) is the Q-path signal of the demodulated reference signal S7, S 7I (i) is the I-channel signal of the demodulated reference signal S7.

[0049] Step 16: Obtain the Doppler phase error θ of the current sampling signal based on the demodulation reference signal S7 m .

[0050] Step 17: Eliminate the Doppler phase error based on the demodulation reference signal S7 to generate a demodulation reference signal S8 after correcting the phase error:

[0051] S8=S7*(cosθ m +j sinθ m )

[0052] Step 18: Set the modulation format and symbol rate according to the demodulation reference signal S8 to generate a theoretical demodulation reference signal

[0053] Step 19: Demodulate the reference signal according to the theory Estimate the channel model R′ of the current sampling signal;

[0054]

[0055] in, for The conjugate function of .

[0056] Step 20: Smooth the demodulated reference signal S8 through interpolation filtering to form the communication signal S9, and find the optimal signal point of the sampling signal.

[0057] Step 21: Eliminate the channel error based on the estimated channel model R′ and the communication signal S9 to form a communication signal S without channel parameters. 10 :

[0058]

[0059] in, is the conjugate function of R′.

[0060] Step 22: The communication signal S after eliminating the channel error 10 Convert from time domain to time-frequency domain signal Y(m,n).

[0061]

[0062] Among them, g rx (t-τ) is the receiving shaping filter function, Δf is the subcarrier spacing, v is the modulation signal bandwidth, τ is the duration of the modulation signal; m is the current subcarrier position number, and n is the current signal time slot position number.

[0063] Step 23: Convert the time-frequency domain signal Y(m,n) to the delay-Doppler domain signal y(k,l):

[0064]

[0065] Where M is the number of subcarriers, N is the number of signal time slots, k is the delay domain number, and l is the Doppler domain number.

[0066] Step 24: Demodulate the delay-Doppler domain signal y(k,l) according to the modulation format and symbol rate of the delay-Doppler domain signal y(k,l) to obtain a demodulated signal B(i).

[0067] Step 25: Based on the modulation format and symbol rate of the communication signal s(t), a reference modulation signal B0(i) is generated by local direct mapping. The error vector magnitude (EVM) of this communication is then calculated using the demodulated signal B(i) and the reference modulation signal B0(i):

[0068]

[0069] Wherein, |B0(i)| is the amplitude value of the reference modulation signal B0(i).

[0070] Based on the above-mentioned orthogonal time-frequency-space modulation signal demodulation and analysis method, the present invention also provides the following implementation device:

[0071] A device for demodulating and analyzing orthogonal time-frequency-space modulation signals, characterized in that it includes a data acquisition unit, an IQ imbalance calculation unit, an amplitude error calculation unit, a continuous phase signal generation unit, a convolution detection frame header determination unit, a guard time slot 1 removal unit, a reception reference signal 1 acquisition unit, a sampling phase error acquisition unit, a theoretical demodulation reference signal 1 generation unit, a channel model extraction unit, a Doppler frequency error calculation unit, a Doppler frequency error elimination unit, a guard time slot 2 removal unit, a reception reference signal 2 acquisition unit, a phase error calculation unit, a Doppler phase error elimination unit, a theoretical demodulation reference signal 2 generation unit, a channel estimation unit, an interpolation and smoothing unit, a channel error elimination unit, a Wigner transform unit, a symplectic finite Fourier transform unit, a digital modulation and demodulation unit, and an error vector magnitude (EVM) calculation unit.

[0072] The data acquisition unit is used to digitize the collected communication signal s(t) and perform IQ demodulation to form the first I-channel data S I (i) The first Q-channel data S Q (i) sending the first I-channel data and the first Q-channel data to the IQ imbalance calculation unit and the convolution detection and frame header determination unit, and saving them to the local memory at the same time.

[0073] The IQ imbalance calculation unit is used to eliminate the first I-channel data S I (i) and the first Q-channel data S Q (i) DC signal, and obtain the second I-way data S′ I (i) The second Q-channel data S′ Q (i); Calculate the second I-way data S' I (i) The amplitude difference <Δ(S I )> and the second Q-channel data S′ Q (i) The amplitude difference <Δ(S Q )>, and calculate the IQ quadrature imbalance coefficient ε according to the amplitude difference; the IQ quadrature imbalance coefficient ε is output as the result, and the second I-way data S′ is output as the result. I (i) Second Q-channel data S′ Q (i) Amplitude difference < Δ(S I )>, amplitude difference <Δ(S Q )> and the IQ quadrature imbalance coefficient ε are sent to the amplitude error calculation unit.

[0074] The amplitude error calculation unit is used to calculate the amplitude error according to the second I-way data S' I (i) Second Q-channel data S′ Q (i) Amplitude difference < Δ(S I )>, amplitude difference <Δ(S Q )> and the IQ quadrature imbalance coefficient ε to calculate the amplitude error ε of the communication signal s(t) collected this time A , and the amplitude error ε A Output as result.

[0075] The continuous phase signal generating unit is used to generate a first I-way continuous phase signal Y according to the sampling period and symbol rate of the communication signal s(t). I (i) and the first Q-path continuous phase signal Y Q (i) and sent to the convolution detection and determination frame header unit.

[0076] The convolution detection determines the frame header unit for using the continuous phase signal Y I (i) Y Q (i) Second I-way data S′ I (i) Second Q-channel data S′ Q (i) Perform convolution calculation to form the third I-way data S″ I (i) and the third Q-channel data S″ Q (i); Re-test S″ I (i) and S″ Q The phase of (i) is θ(i), and the phase mutation point is S″ I (i) and S″ Q (i) The data frame header starting position; then the third I-way data S " I (i) The third Q-channel data S″ Q (i) and the data frame header starting position information are sent to the guard time slot 1 removal unit and the Doppler frequency error elimination unit.

[0077] The protection time slot 1 unit is removed, and the third I-way data S" is determined according to the starting position information of the data frame header. I (i) The third Q-channel data S″ Q (i) the starting frame header position; then set the CP parameter according to the communication signal s (t), remove the third I-way data S " I (i) The third Q-channel data S″ Q The guard time slot data of (i) is formed into a communication signal S4, and sent to the acquisition and reception reference signal 1 unit.

[0078] The unit for obtaining the received reference signal 1 is used to extract the I-channel reference data S′ at the reference signal position in the communication signal S4 according to the setting of the reference signal position and format of the communication signal s(t). 4I (i) and Q-path reference data S′ 4Q (i) and sent to the sampling phase error acquisition unit.

[0079] The sampling phase error acquisition unit is used to calculate the I-way reference data S' by phase continuity characteristics. 4I (i) and Q-path reference data S′ 4Q (i) The sampling phase error ε θ ; and sample the phase error ε θ , I-way reference data S′ 4I (i) and Q-path reference data S′ 4Q (i) Sending to the channel model extraction unit.

[0080] The generating unit of theoretical demodulation reference signal 1 is used to generate theoretical demodulation reference I signal according to the modulation format and symbol rate of the communication signal s(t). and Q-channel signal And sent to the channel model extraction unit and the channel estimation unit.

[0081] The channel model extraction unit is used to extract the channel model through I-way reference data S' 4I (i) Q-path reference data S′ 4Q (i), and theoretical demodulation reference I signal and Q-channel signal Extract the channel model R of the communication signal S′4 and combine the channel model R and the sampling phase error ε θ The data is sent to the Doppler frequency error calculation unit.

[0082] The Doppler frequency error calculation unit is used to calculate the Doppler frequency error according to the sampling phase error ε θ and the channel model R, calculate the Doppler frequency error ε f ; Then the Doppler frequency error ε f The result is output and sent to the Doppler frequency error elimination unit.

[0083] The Doppler frequency error elimination unit, since the communication signal S′4 comes from the communication signal S″, the Doppler frequency errors of the two signals are the same. According to the Doppler frequency error ε fGenerate data H for eliminating Doppler frequency error; then eliminate the Doppler frequency error of the communication signal S", obtain the main demodulation channel signal S5 and send it to the protection time slot removal unit 2, and at the same time, send the data frame header starting position information obtained by the convolution detection determination frame header unit to the protection time slot removal unit 2.

[0084] The protection time slot removal unit 2 determines the starting frame header position of S5 according to the starting position information of the data frame header, then sets the CP parameter according to the communication signal s(t), removes the protection time slot data of the channel signal S5, obtains the communication signal S6 and sends it to the acquisition reception reference signal 2 unit.

[0085] The receiving reference signal acquisition unit 2 is configured to extract the demodulation reference signal S7 at the reference signal position in the communication signal S6 according to the setting of the reference signal position and format by the communication signal S6 and send the demodulation reference signal S7 to the phase error calculation unit.

[0086] The phase error calculation unit is used to generate a theoretical phase value based on the phase continuity characteristic, and then calculate the sampling phase error ε′ of the demodulation reference signal S7 θ , and the sampling phase error ε′ θ As the result output, the demodulation reference signal S7 and the sampling phase error ε′ are simultaneously θ The data is sent to the Doppler phase error elimination unit.

[0087] The Doppler phase error elimination unit is used to eliminate the Doppler phase error according to the sampling phase error ε′ θ Generate data θ to eliminate Doppler phase error m Then eliminate the Doppler phase error of the demodulation reference signal S7 to form a demodulation reference signal S8 after correcting the phase error and send it to the channel estimation unit.

[0088] The generating unit of the theoretical demodulation reference signal 2 is used to generate the theoretical demodulation reference signal according to the modulation format and symbol rate of the demodulation reference signal S8. And sent to the channel estimation unit.

[0089] The channel estimation unit is used to demodulate the reference signal according to the theory The channel model R′ of the demodulation reference signal S8 is estimated and the demodulation reference signal S8 and the channel model R′ are sent to the interpolation and smoothing unit.

[0090] The interpolation smoothing unit smoothes the demodulation reference signal S8 through interpolation filtering to form a communication signal S9, that is, finds the best signal point of the sampling signal; and then sends the channel model R′ and the communication signal S9 to the channel error elimination unit.

[0091] The channel error elimination unit eliminates the channel error of the communication signal S9 according to the channel model R′ to form a communication signal S9 without channel parameters. 10 , and sent to the Wigner transformation unit.

[0092] The Wigner transformation unit is used to transform the communication signal S 10 The time domain is converted into a time-frequency domain signal Y(m,n) and sent to the symplectic finite Fourier transform unit.

[0093] The symplectic finite Fourier transform unit is used to convert the time-frequency domain signal Y(m,n) into a delay-Doppler domain signal y(k,1) and send it to the digital modulation and demodulation unit.

[0094] The digital modulation and demodulation unit demodulates the delay-Doppler domain signal y(k, 1) according to the modulation format and symbol rate of the delay-Doppler domain signal y(k, 1), obtains a demodulated signal B(i), and sends it to the error vector magnitude (EVM) calculation unit.

[0095] The error vector magnitude (EVM) calculation unit directly maps the reference modulation signal B0(i) locally according to the modulation format and symbol rate of the communication signal s(t); and then calculates the error vector magnitude (EVM) value of this communication using the demodulated signal B(i) and the reference modulation signal B0(i), and outputs the error vector magnitude (EVM) value as a result.

[0096] The present invention has the following beneficial technical effects: through this method, a high-precision large Doppler frequency shift orthogonal time-frequency space modulation 6G satellite communication signal demodulation and analysis can be realized, and analysis results such as IQ imbalance, amplitude error, frequency error, phase error, error vector magnitude (EVM) and the like can be calculated; at the same time, various errors brought about by the satellite communication signal in the large Doppler frequency shift communication process can be eliminated, and a test and verification means can be provided for the research on new modulation signals of 6G satellite communication, which can well guarantee the development of 6G satellite communication technology and equipment research and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 The present invention is a block diagram of a high-precision large Doppler shift orthogonal time-frequency space modulation 6G satellite communication signal demodulation and analysis device. DETAILED DESCRIPTION

[0098] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is described in detail below with reference to the accompanying drawings.

[0099] A large Doppler shift OTFS satellite communication demodulation and analysis method according to this embodiment includes the following steps:

[0100] Step 1: Digitize the collected communication signal s(t) and perform IQ demodulation to form the first I-channel data S I (i) The first Q-channel data S Q (i) saving the first I-channel data and the first Q-channel data to a fixed storage space for subsequent analysis;

[0101] S I (i)=s(t)*cos(ω c T s )

[0102] S Q (i)=s(t)*sin(ω c T s )

[0103] Among them, i represents the sequence number of the sampling point, ω c is the carrier angular frequency, T s is the sampling period.

[0104] Step 2: Eliminate the first I-way data S I (i) and the first Q-channel data S Q (i) DC signal, and obtain the second I-way data S′ I (i) The second Q-channel data S′ Q (i)

[0105] S′ I (i) = S I (i)- I >

[0106] S′ Q (i) = S Q (i)- Q >

[0107] in, I > for S I The DC estimate of (i), Q > for S Q (i) DC estimate;

[0108] Then calculate the IQ quadrature imbalance coefficient ε:

[0109]

[0110] Among them, <Δ(S I )> is S′ I (i) the amplitude difference, <Δ(S Q )> is S′ Q (i) The amplitude difference.

[0111] ​​​​Step 3: Through the second I-way data S' I (i) The second Q-channel data S′ Q (i) Calculate the amplitude error ε of the communication signal s(t) collected this time A :

[0112]

[0113] Step 4: Generate the first I-way continuous phase signal Y according to the sampling period and symbol rate of the communication signal s(t) I (i) and the first Q-path continuous phase signal Y Q (i)

[0114] Y I (i) = Acos(2πωT)

[0115] Y Q (i) = Asin(2πωT)

[0116] Where A is the continuous phase signal Y I (i) and Y Q (i) is the amplitude, ω is the continuous phase signal Y I (i) and Y Q (i) is the angular frequency, T is the continuous phase signal Y I (i) and Y Q (i) The sampling period.

[0117] Step 5: Using the continuous phase signal Y I (i) Y Q (i) Second I-way data S′ Q (i) Second Q-channel data S′ Q (i) Perform convolution to form the third I-way data S″ I (i) and the third Q-channel data S″ Q (i)

[0118] S″ I (i) = S′ I (i)*Y I (i)

[0119] S″ Q (i) = S′ Q (i)*Y Q (i)

[0120] At this time, detect S″ again I (i) and S″ Q Phase θ(i) of (i):

[0121] θ(i)=tan -1 (S″ Q(i) / S″ I (i))

[0122] The phase mutation point is S″ I (i) and S″ Q (i) Data frame header.

[0123] Step 6: Set the CP parameter according to the communication signal s(t) to remove the guard time slot data to form the communication signal S4.

[0124] Step 7: Extract the I-channel reference data S′ at the reference signal position in the communication signal S4 according to the setting of the reference signal position and format of the communication signal s(t). 4I (i) and Q-path reference data S′ 4Q (i).

[0125] Step 8: Calculate the I-channel reference data S′ based on the phase continuity characteristics 4I (i) and Q-path reference data S′ 4Q The sampling phase error ε in (i) θ :

[0126]

[0127] in, is the theoretical phase value of the i-th sampling point.

[0128] Step 9: Generate a theoretical demodulation reference I signal based on the modulation format and symbol rate of the communication signal s(t) and Q-channel signal

[0129] Step 10: I-way reference data S′ obtained in step 7 4I (i) and Q-path reference data S′ 4Q (i), and the theoretical demodulation reference I signal obtained in step 9 and Q-channel signal Extract the channel model R for this communication:

[0130]

[0131] in, for The conjugate function of .

[0132] Step 11: Calculate the Doppler frequency error ε based on the communication channel model R f :

[0133]

[0134] Among them, R Q(i) is the Q-path signal of the channel model R, R I (i) is the I-path signal of the channel model R.

[0135] Step 12: According to the Doppler frequency error ε f , generate the Doppler frequency error elimination data H; then eliminate the Doppler frequency error of the communication signal S4 to obtain the main demodulation channel signal S5:

[0136] S5=S4 / H

[0137] Step 13: Set the CP parameter again according to the main demodulation channel signal S5 to remove the guard time slot data to obtain the communication signal S6.

[0138] Step 14: According to the settings of the reference signal position and format of the communication signal S6, the demodulation reference signal S7 at the reference signal position in the communication signal S6 is extracted.

[0139] Step 15: Calculate the sampling phase error ε′ of the demodulation reference signal S7 based on the phase continuity characteristic θ :

[0140]

[0141] Among them, S 7Q (i) is the Q-path signal of the demodulated reference signal S7, S 7I (i) is the I-channel signal of the demodulated reference signal S7.

[0142] Step 16: Obtain the Doppler phase error θ of the current sampling signal based on the demodulation reference signal S7 m .

[0143] Step 17: Eliminate the Doppler phase error based on the demodulation reference signal S7 to generate a demodulation reference signal S8 after correcting the phase error:

[0144] S8=S7*(cosθ m +j sinθ m )

[0145] Step 18: Set the modulation format and symbol rate according to the demodulation reference signal S8 to generate a theoretical demodulation reference signal

[0146] Step 19: Demodulate the reference signal according to the theory Estimate the channel model R′ of the current sampling signal;

[0147]

[0148] in, for The conjugate function of .

[0149] Step 20: Smooth the demodulated reference signal S8 through interpolation filtering to form the communication signal S9, and find the optimal signal point of the sampling signal.

[0150] Step 21: Eliminate the channel error based on the estimated channel model R′ and the communication signal S9 to form a communication signal S without channel parameters. 10 :

[0151]

[0152] in, is the conjugate function of R′.

[0153] Step 22: The communication signal S after eliminating the channel error 10 Convert from time domain to time-frequency domain signal Y(m,n).

[0154]

[0155] Among them, g rx (t-τ) is the receiving shaping filter function, Δf is the subcarrier spacing, v is the modulation signal bandwidth, τ is the duration of the modulation signal; m is the current subcarrier position number, and n is the current signal time slot position number.

[0156] Step 23: Convert the time-frequency domain signal Y(m,n) to the delay-Doppler domain signal y(k,l):

[0157]

[0158] Where M is the number of subcarriers, N is the number of signal time slots, k is the delay domain number, and l is the Doppler domain number.

[0159] Step 24: Demodulate the delay-Doppler domain signal y(k,l) according to the modulation format and symbol rate of the delay-Doppler domain signal y(k,l) to obtain a demodulated signal B(i).

[0160] Step 25: Based on the modulation format and symbol rate of the communication signal s(t), a reference modulation signal B0(i) is generated by local direct mapping. The error vector magnitude (EVM) of this communication is then calculated using the demodulated signal B(i) and the reference modulation signal B0(i):

[0161]

[0162] Wherein, |B0(i)| is the amplitude value of the reference modulation signal B0(i).

[0163] Based on the above-mentioned orthogonal time-frequency-space modulation signal demodulation and analysis method, this embodiment further provides the following implementation device:

[0164] A device for demodulating and analyzing orthogonal time-frequency spatial modulation signals, characterized in that it includes a data acquisition unit, an IQ imbalance calculation unit, an amplitude error calculation unit, a continuous phase signal generation unit, a convolution detection frame header determination unit, a guard slot 1 removal unit, a reception reference signal 1 acquisition unit, a sampling phase error acquisition unit, a theoretical demodulation reference signal 1 generation unit, a channel model extraction unit, a Doppler frequency error calculation unit, a Doppler frequency error elimination unit, a guard slot 2 removal unit, a reception reference signal 2 acquisition unit, a phase error calculation unit, a Doppler phase error elimination unit, a theoretical demodulation reference signal 2 generation unit, a channel estimation unit, an interpolation and smoothing unit, a channel error elimination unit, a Wigner transform unit, a symplectic finite Fourier transform unit, a digital modulation and demodulation unit, and an error vector magnitude (EVM) calculation unit.

[0165] The data acquisition unit is used to digitize the collected communication signal s(t) and perform IQ demodulation to form the first I-channel data S I (i) The first Q-channel data S Q (i) sending the first I-channel data and the first Q-channel data to the IQ imbalance calculation unit and the convolution detection and frame header determination unit, and saving them to the local memory at the same time.

[0166] The IQ imbalance calculation unit is used to eliminate the first I-channel data S I (i) and the first Q-channel data S Q (i) DC signal, and obtain the second I-way data S′ I (i) The second Q-channel data S′ Q (i); Calculate the second I-way data S' I (i) The amplitude difference <Δ(S I )> and the second Q-channel data S′ Q (i) The amplitude difference <Δ(S Q )>, and calculate the IQ quadrature imbalance coefficient ε according to the amplitude difference; the IQ quadrature imbalance coefficient ε is output as the result, and the second I-way data S′ is output as the result. I (i) Second Q-channel data S′ Q (i) Amplitude difference < Δ(S I )>, amplitude difference <Δ(S Q )> and the IQ quadrature imbalance coefficient ε are sent to the amplitude error calculation unit.

[0167] The amplitude error calculation unit is used to calculate the amplitude error according to the second I-way data S' I (i) Second Q-channel data S′Q (i) Amplitude difference < Δ(S I )>, amplitude difference <Δ(S Q )> and the IQ quadrature imbalance coefficient ε to calculate the amplitude error ε of the communication signal s(t) collected this time A , and the amplitude error ε A Output as result.

[0168] The continuous phase signal generating unit is used to generate a first I-way continuous phase signal Y according to the sampling period and symbol rate of the communication signal s(t). I (i) and the first Q-path continuous phase signal Y Q (i) and sent to the convolution detection and determination frame header unit.

[0169] The convolution detection determines the frame header unit for using the continuous phase signal Y I (i) Y Q (i) Second I-way data S′ I (i) Second Q-channel data S′ Q (i) Perform convolution calculation to form the third I-way data S″ I (i) and the third Q-channel data S″ Q (i); Re-test S″ I (i) and S″ Q The phase of (i) is θ(i), and the phase mutation point is S″ I (i) and S″ Q (i) The data frame header starting position; then the third I-way data S " I (i) The third Q-channel data S″ Q (i) and the data frame header starting position information are sent to the guard time slot 1 removal unit and the Doppler frequency error elimination unit.

[0170] The protection time slot 1 unit is removed, and the third I-way data S" is determined according to the starting position information of the data frame header. I (i) The third Q-channel data S″ Q (i) the starting frame header position; then set the CP parameter according to the communication signal s (t), remove the third I-way data S " I (i) The third Q-channel data S″ Q The guard time slot data of (i) is formed into a communication signal S4, and sent to the acquisition and reception reference signal 1 unit.

[0171] The unit for obtaining the received reference signal 1 is used to extract the I-channel reference data S′ at the reference signal position in the communication signal S4 according to the setting of the reference signal position and format of the communication signal s(t). 4I (i) and Q-path reference data S′ 4Q(i) and sent to the sampling phase error acquisition unit.

[0172] The sampling phase error acquisition unit is used to calculate the I-way reference data S' by phase continuity characteristics. 4I (i) and Q-path reference data S′ 4Q (i) The sampling phase error ε θ ; and sample the phase error ε θ , I-way reference data S′ 4I (i) and Q-path reference data S′ 4Q (i) Sending to the channel model extraction unit.

[0173] The generating unit of theoretical demodulation reference signal 1 is used to generate theoretical demodulation reference I signal according to the modulation format and symbol rate of the communication signal s(t). and Q-channel signal And sent to the channel model extraction unit and the channel estimation unit.

[0174] The channel model extraction unit is used to extract the channel model through I-way reference data S' 4I (i) Q-path reference data S′ 4Q (i), and theoretical demodulation reference I signal and Q-channel signal Extract the channel model R of the communication signal S′4 and combine the channel model R and the sampling phase error ε θ The data is sent to the Doppler frequency error calculation unit.

[0175] The Doppler frequency error calculation unit is used to calculate the Doppler frequency error according to the sampling phase error ε θ and the channel model R, calculate the Doppler frequency error ε f ; Then the Doppler frequency error ε f The result is output and sent to the Doppler frequency error elimination unit.

[0176] The Doppler frequency error elimination unit, since the communication signal S′4 comes from the communication signal S″, the Doppler frequency errors of the two signals are the same. According to the Doppler frequency error ε f Generate data H for eliminating Doppler frequency error; then eliminate the Doppler frequency error of the communication signal S", obtain the main demodulation channel signal S5 and send it to the protection time slot removal unit 2, and at the same time, send the data frame header starting position information obtained by the convolution detection determination frame header unit to the protection time slot removal unit 2.

[0177] The protection time slot removal unit 2 determines the starting frame header position of S5 according to the starting position information of the data frame header, then sets the CP parameter according to the communication signal s(t), removes the protection time slot data of the channel signal S5, obtains the communication signal S6 and sends it to the acquisition reception reference signal 2 unit.

[0178] The receiving reference signal acquisition unit 2 is configured to extract the demodulation reference signal S7 at the reference signal position in the communication signal S6 according to the setting of the reference signal position and format by the communication signal S6 and send the demodulation reference signal S7 to the phase error calculation unit.

[0179] The phase error calculation unit is used to generate a theoretical phase value based on the phase continuity characteristic, and then calculate the sampling phase error ε′ of the demodulation reference signal S7 θ , and the sampling phase error ε′ θ As the result output, the demodulation reference signal S7 and the sampling phase error ε′ are simultaneously θ The data is sent to the Doppler phase error elimination unit.

[0180] The Doppler phase error elimination unit is used to eliminate the Doppler phase error according to the sampling phase error ε′ θ Generate data θ to eliminate Doppler phase error m Then eliminate the Doppler phase error of the demodulation reference signal S7 to form a demodulation reference signal S8 after correcting the phase error and send it to the channel estimation unit.

[0181] The generating unit of the theoretical demodulation reference signal 2 is used to generate the theoretical demodulation reference signal according to the modulation format and symbol rate of the demodulation reference signal S8. And sent to the channel estimation unit.

[0182] The channel estimation unit is used to demodulate the reference signal according to the theory The channel model R′ of the demodulation reference signal S8 is estimated and the demodulation reference signal S8 and the channel model R′ are sent to the interpolation and smoothing unit.

[0183] The interpolation smoothing unit smoothes the demodulation reference signal S8 through interpolation filtering to form a communication signal S9, that is, finds the best signal point of the sampling signal; and then sends the channel model R′ and the communication signal S9 to the channel error elimination unit.

[0184] The channel error elimination unit eliminates the channel error of the communication signal S9 according to the channel model R′ to form a communication signal S9 without channel parameters. 10 , and sent to the Wigner transformation unit.

[0185] The Wigner transformation unit is used to transform the communication signal S 10The time domain is converted into a time-frequency domain signal Y(m,n) and sent to the symplectic finite Fourier transform unit.

[0186] The symplectic finite Fourier transform unit is used to convert the time-frequency domain signal Y(m,n) into a delay-Doppler domain signal y(k,l) and send it to the digital modulation and demodulation unit.

[0187] The digital modulation and demodulation unit demodulates the delay-Doppler domain signal y(k,l) according to the modulation format and symbol rate of the delay-Doppler domain signal y(k,1), obtains a demodulated signal B(i), and sends it to the error vector magnitude (EVM) calculation unit.

[0188] The error vector magnitude (EVM) calculation unit directly maps the reference modulation signal B0(i) locally according to the modulation format and symbol rate of the communication signal s(t); and then calculates the error vector magnitude (EVM) value of this communication using the demodulated signal B(i) and the reference modulation signal B0(i), and outputs the error vector magnitude (EVM) value as a result.

Claims

1. A large Doppler shift OTFS satellite communication demodulation and analysis method, characterized in that: The following steps are involved: Step 1: Digitize the collected communication signal s(t) and perform IQ demodulation to form the first I-channel data S I (i) The first Q-channel data S Q (i) saving the first I-channel data and the first Q-channel data into a fixed storage space; Step 2: Eliminate the first I-way data S I (i) and the first Q-channel data S Q (i) DC signal, obtain the second I-way data S' I (i) Second Q-channel data S′ Q (i); The IQ quadrature imbalance coefficient ε is calculated as: Among them, <Δ(S I )> is S′ I (i) the amplitude difference, <Δ(S Q )> is S′ Q (i) the amplitude difference; Step 3: Through the second I-way data S' I (i) Second Q-channel data S′ Q (i) Calculate the amplitude error ε of the communication signal s(t) collected this time A ; Step 4: Generate the first I-way continuous phase signal Y according to the sampling period and symbol rate of the communication signal s(t) I (i) and the first Q-path continuous phase signal Y Q (i); Step 5: Using the continuous phase signal Y I (i) Y Q (i) The second I-way data S′ I (i) Second Q-channel data S′ Q (i) Perform convolution to form the third I-way data S″ I (i) and the third Q-channel data S″ Q (i); Detect S″ I (i) and S″ Q The phase of (i) is θ(i), and the phase mutation point is S″ I (i) and S″ Q (i) Data frame header; Step 6: Set the CP parameter according to the communication signal s(t) to remove the guard slot data to form the communication signal S4; Step 7: Extract the I-channel reference data S′ at the reference signal position in the communication signal S4 according to the setting of the reference signal position and format of the communication signal s(t). 4I (i) and Q-path reference data S′ 4Q (i); Step 8: Calculate the I-channel reference data S′ based on the phase continuity characteristics 4I (i) and Q-path reference data S′ 4Q The sampling phase error ε in (i) θ ; Step 9: Generate a theoretical demodulation reference I signal based on the modulation format and symbol rate of the communication signal s(t) and Q-channel signal Step 10: I-way reference data S′ obtained in step 7 4I (i) and Q-path reference data S′ 4Q (i), and the theoretical demodulation reference I signal obtained in step 9 and Q-channel signal Extract the channel model R of this communication; Step 11: Calculate the Doppler frequency error ε based on the communication channel model R f ; Step 12: According to the Doppler frequency error ε f , generating Doppler frequency error elimination data H; then eliminating the Doppler frequency error of the communication signal S4 to obtain the main demodulation channel signal S5; Step 13: Set the CP parameter again according to the main demodulation channel signal S5 to remove the guard time slot data to obtain the communication signal S6; Step 14: extracting a demodulation reference signal S7 at the reference signal position in the communication signal S6 according to the setting of the reference signal position and format in the communication signal S6; Step 15: Calculate the sampling phase error ε′ of the demodulation reference signal S7 based on the phase continuity characteristic θ ; Step 16: Obtain the Doppler phase error θ of the current sampling signal based on the demodulation reference signal S7 m； Step 17: Eliminate the Doppler phase error based on the demodulation reference signal S7 to generate a demodulation reference signal S8 after correcting the phase error. Step 18: Set the modulation format and symbol rate according to the demodulation reference signal S8 to generate a theoretical demodulation reference signal Step 19: Demodulate the reference signal according to the theory Estimate the channel model R′ of the current sampling signal; Step 20: Smoothing the demodulated reference signal S8 through interpolation filtering to form a communication signal S9, and finding the optimal signal point of the sampling signal; Step 21: Eliminate the channel error based on the estimated channel model R′ and the communication signal S9 to form a communication signal S without channel parameters. 10 ; Step 22: The communication signal S after eliminating the channel error 10 Convert from time domain to time-frequency domain signal Y(m,n); Step 23: Convert the time-frequency domain signal Y(m,n) to the delay-Doppler domain signal y(k,l); Step 24: Demodulate the delay-Doppler domain signal y(k,l) according to its modulation format and symbol rate to obtain a demodulated signal B(i). Step 25: Based on the modulation format and symbol rate of the communication signal s(t), a reference modulation signal B0(i) is generated by local direct mapping. The error vector magnitude (EVM) value of this communication is then calculated using the demodulated signal B(i) and the reference modulation signal B0(i).

2. A device for demodulating and analyzing orthogonal time-frequency-space modulation signals, characterized in that: It includes a data acquisition unit, an IQ imbalance calculation unit, an amplitude error calculation unit, a continuous phase signal generation unit, a convolution detection frame header determination unit, a guard time slot 1 removal unit, a reception reference signal 1 acquisition unit, a sampling phase error acquisition unit, a theoretical demodulation reference signal 1 generation unit, a channel model extraction unit, a Doppler frequency error calculation unit, a Doppler frequency error elimination unit, a guard time slot 2 removal unit, a reception reference signal 2 acquisition unit, a phase error calculation unit, a Doppler phase error elimination unit, a theoretical demodulation reference signal 2 generation unit, a channel estimation unit, an interpolation and smoothing unit, a channel error elimination unit, a Wigner transform unit, a symplectic finite Fourier transform unit, a digital modulation and demodulation unit, and an error vector magnitude (EVM) calculation unit. The data acquisition unit is used to digitize the collected communication signal s(t) and perform IQ demodulation to form the first I-channel data S I (i) The first Q-channel data S Q (i) sending the first I-channel data and the first Q-channel data to the IQ imbalance calculation unit and the convolution detection and frame header determination unit, and saving them to the local memory; The IQ imbalance calculation unit is used to eliminate the first I-channel data S I (i) and the first Q-channel data S Q (i) DC signal, obtain the second I-way data S' I (i) Second Q-channel data S′ Q (i); Calculate the second I-way data S' I (i) The amplitude difference <Δ(S I )> and the second Q-channel data S′ Q (i) The amplitude difference <Δ(S Q )>, and calculate the IQ quadrature imbalance coefficient ε according to the amplitude difference; the IQ quadrature imbalance coefficient ε is output as the result, and the second I-way data S′ is output as the result. I (i) Second Q-channel data S′ Q (i) Amplitude difference < Δ(S I )>, amplitude difference <Δ(S Q )> and the IQ quadrature imbalance coefficient ε, are sent to the amplitude error calculation unit; The amplitude error calculation unit is used to calculate the amplitude error according to the second I-way data S' I (i) Second Q-channel data S′ Q (i) Amplitude difference < Δ(S I )>, amplitude difference <Δ(S Q )> and the IQ quadrature imbalance coefficient ε to calculate the amplitude error ε of the communication signal s(t) collected this time A , and the amplitude error ε A Output as result; The continuous phase signal generating unit is used to generate a first I-way continuous phase signal Y according to the sampling period and symbol rate of the communication signal s(t). I (i) and the first Q-path continuous phase signal Y Q (i) and sending it to the convolution detection and frame header determination unit; The convolution detection determines the frame header unit for using the continuous phase signal Y I (i) Y Q (i) The second I-way data S′ I (i) Second Q-channel data S′ Q (i) Perform convolution calculation to form the third I-way data S″ I (i) and the third Q-channel data S″ Q (i); Re-test S″ I (i) and S″ Q The phase of (i) is θ(i), and the phase mutation point is S″ I (i) and S″ Q (i) The starting position of the data frame header; Then the third I-way data S″ I (i) The third Q-channel data S″ Q (i) and the data frame header starting position information are sent to the protection time slot removal unit and the Doppler frequency error elimination unit; The protection time slot 1 unit is removed, and the third I-way data S" is determined according to the starting position information of the data frame header. I (i) The third Q-channel data S″ Q (i) the starting frame header position; then set the CP parameter according to the communication signal s (t), remove the third I-way data S " I (i) The third Q-channel data S″ Q (i) guard time slot data, thereby forming a communication signal S4, and sending it to the acquisition and reception reference signal 1 unit; The unit for obtaining the received reference signal 1 is used to extract the I-channel reference data S′ at the reference signal position in the communication signal S4 according to the setting of the reference signal position and format of the communication signal s(t). 4I (i) and Q-path reference data S′ 4Q (i) and sending it to the sampling phase error acquisition unit; The sampling phase error acquisition unit is used to calculate the I-way reference data S' by phase continuity characteristics. 4I (i) and Q-path reference data S′ 4Q (i) The sampling phase error ε θ ; and sample the phase error ε θ , I-way reference data S′ 4I (i) and Q-path reference data S′ 4Q (i) sending to the channel model extraction unit; The generating unit of theoretical demodulation reference signal 1 is used to generate theoretical demodulation reference I signal according to the modulation format and symbol rate of the communication signal s(t). and Q-channel signal and sent to the channel model extraction unit and the channel estimation unit; The channel model extraction unit is used to extract the channel model through I-way reference data S' 4I (i) Q-path reference data S′ 4Q (i), and theoretical demodulation reference I signal and Q-channel signal Extract the channel model R of the communication signal S′4 and combine the channel model R and the sampling phase error ε θ Sending to the Doppler frequency error calculation unit; The Doppler frequency error calculation unit is used to calculate the Doppler frequency error according to the sampling phase error ε θ and the channel model R, calculate the Doppler frequency error ε f ; Then the Doppler frequency error ε f Output as a result and send to the Doppler frequency error elimination unit; The Doppler frequency error elimination unit is configured to eliminate the Doppler frequency error ε f Generate Doppler frequency error elimination data H; then eliminate the Doppler frequency error of the communication signal S ", obtain the main demodulation channel signal S5 and send it to the protection time slot removal unit 2, and at the same time send the data frame header starting position information obtained by the convolution detection determination frame header unit to the protection time slot removal unit 2; The protection time slot removal unit 2 determines the starting frame header position of S5 according to the starting position information of the data frame header, sets the CP parameter according to the communication signal s(t), removes the protection time slot data of the channel signal S5, obtains the communication signal S6 and sends it to the acquisition reception reference signal 2 unit; The receiving reference signal acquisition unit 2 is configured to extract a demodulation reference signal S7 at the reference signal position in the communication signal S6 according to the setting of the reference signal position and format of the communication signal S6 and send the demodulation reference signal S7 to the phase error calculation unit; The phase error calculation unit is used to generate a theoretical phase value based on the phase continuity characteristic, and then calculate the sampling phase error ε′ of the demodulation reference signal S7 θ , and the sampling phase error ε′ θ As the result output, the demodulation reference signal S7 and the sampling phase error ε′ are simultaneously θ Sending to the Doppler phase error elimination unit; The Doppler phase error elimination unit is used to eliminate the Doppler phase error according to the sampling phase error ε′ θ Generate data θ to eliminate Doppler phase error m ; Then, the Doppler phase error of the demodulation reference signal S7 is eliminated to form a demodulation reference signal S8 after correcting the phase error and send it to the channel estimation unit; The generating unit of the theoretical demodulation reference signal 2 is used to generate the theoretical demodulation reference signal according to the modulation format and symbol rate of the demodulation reference signal S8. and sending it to the channel estimation unit; The channel estimation unit is used to demodulate the reference signal according to the theory Estimating and obtaining a channel model R′ of a demodulation reference signal S8, and sending the demodulation reference signal S8 and the channel model R′ to the interpolation and smoothing unit; The interpolation smoothing unit smoothes the demodulated reference signal S8 by interpolation filtering to form a communication signal S9, that is, finds the optimal signal point of the sampling signal; Then the channel model R′ and the communication signal S9 are sent to the channel error elimination unit; The channel error elimination unit eliminates the channel error of the communication signal S9 according to the channel model R′ to form a communication signal S without channel parameters. 10 , and sent to the Wigner transformation unit; The Wigner transformation unit is used to transform the communication signal S 10 Converting the time domain into a time-frequency domain signal Y(m,n) and sending it to the symplectic finite Fourier transform unit; The symplectic finite Fourier transform unit is used to convert the time-frequency domain signal Y(m,n) into a delay-Doppler domain signal y(k,l) and send it to the digital modulation and demodulation unit; The digital modulation and demodulation unit demodulates the delay-Doppler domain signal y(k,l) according to the modulation format and symbol rate of the delay-Doppler domain signal y(k,l), obtains a demodulated signal B(i), and sends it to the error vector magnitude (EVM) calculation unit; The error vector magnitude (EVM) calculation unit directly maps the reference modulation signal B0(i) locally according to the modulation format and symbol rate of the communication signal s(t); and then calculates the error vector magnitude (EVM) value of this communication using the demodulated signal B(i) and the reference modulation signal B0(i), and outputs the error vector magnitude (EVM) value as a result.

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