Intelligent analysis method for 5G NR signal modulation distortion

Abstract

The invention provides a 5G NR signal modulation distortion intelligent analysis method, and relates to the technical field of signal processing. The method comprises intelligent synchronous detection, carrier synchronization, channel estimation and equalization, reference signal generation and modulation distortion analysis, and the intelligent synchronous detection comprises PSS detection, SSS detection, determination of the maximum sending number Lmax of SS / PBCH in a burst set period, half-frame number detection, determination of SS / PBCH patterns and the burst set period and frame synchronization. According to the modulation distortion analysis, error vector amplitude is calculated, and original point offset, orthogonal error and gain imbalance evaluation are adopted in a matched mode for modulation distortion analysis and evaluation. According to the method, complex parameter configuration of 5G NR signal analysis is reduced through intelligent synchronous detection, high-precision modulation distortion analysis of 5G NR signals is achieved through the provided 5G NR signal modulation distortion test analysis method in a matched mode, the modulation performance of 5G equipment is analyzed on the basis of multiple dimensions, and a foundation is laid for comprehensive index testing of the 5G equipment.

Description

Technical Field

[0001] The present invention relates to the field of signal processing technology, and in particular to a method for intelligent analysis of 5G NR signal modulation distortion. Background Art

[0002] With the market's pursuit of high-bandwidth, high-speed communications, mobile communications have entered the fifth generation of cellular mobile communications (5G). 5G signal testing, particularly in the R&D, production, and support of 5G communication-related equipment such as base stations and chipsets, primarily relies on signal analyzers for receiver testing. As a crucial instrument for RF circuit testing, signal analyzers integrate functions such as spectrum power testing, equipment fault diagnosis, and complex signal modulation and distortion analysis.

[0003] Unlike comprehensive testers, signal analyzers don't interact with base stations and other equipment via signaling, and therefore can't obtain 5G signal configuration parameters. Existing 5G device testing requires manual input of these parameters. The 3GPP protocol specifies specific requirements for 5G device radio frequency and modulation characteristics, and all equipment must comply with these specifications.

[0004] Modulation distortion analysis is the core of 5G NR (New Radio) related tests, and the test process is the most complex. At present, 5G NR modulation analysis solutions mostly use manual configuration analysis solutions, such as Figure 1 This analysis process achieves time-domain synchronization of the frame structure by manually synchronizing parameters such as the broadcast block pattern, burst set period, half-frame offset, subcarrier offset, and number of synchronized broadcast blocks. It then performs frequency offset estimation, channel estimation, and channel equalization, achieving demodulation and finally performing EVM calculation.

[0005] Due to the numerous 5G parameters, the complexity of manual configuration, and the obscure meanings of these parameters, technicians must possess in-depth expertise. Furthermore, 5G devices are complex, and existing test solutions typically only perform error vector magnitude (EVM) testing, which is relatively limited in scope. Therefore, it is imperative to develop an intelligent analysis method for 5G NR signal modulation distortion. This method, by analyzing the modulation performance of 5G devices from multiple dimensions, can assist research and production personnel in conducting comprehensive performance testing. Summary of the Invention

[0006] To address the problems in the prior art of manually configuring 5G signal modulation analysis parameters, which require complex configuration and single test functions, the present invention proposes an intelligent analysis method for 5G NR signal modulation distortion. This method solves the problem of complex manual configuration of 5G NR signal modulation analysis and implements high-precision modulation distortion analysis of 5G NR signals. This method is beneficial for analyzing the modulation performance of 5G devices from multiple dimensions and helps scientific research and production line personnel conduct comprehensive indicator testing.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A 5G NR signal modulation distortion intelligent analysis method is used to perform modulation distortion test analysis on baseband IQ data, including the following steps:

[0009] Step 1, intelligent synchronization detection;

[0010] Step 2: carrier synchronization;

[0011] Step 3: channel estimation and equalization;

[0012] Step 4: Reference signal generation;

[0013] Step 5: Modulation distortion analysis.

[0014] Preferably, in step 1, intelligent synchronization detection is performed on SS / PBCH, the SS / PBCH includes PSS, SSS and PBCH, and the position relationship between the three is fixed. The SS / PBCH index includes a burst set period, an SS / PBCH pattern, the number of SS / PBCHs, and a half-frame number, wherein the burst set period is used to determine how often the SS / PBCH set is sent, the SS / PBCH pattern is used to indicate the time domain arrangement rule of the SS / PBCH, the number of SS / PBCHs is used to indicate the number of SS / PBCHs contained in an SS / PBCH set, and the half-frame number is used to indicate the sending position of the SS / PBCH set.

[0015] Preferably, the intelligent synchronization detection includes the following sub-steps:

[0016] Step 1.1: PSS detection to determine the time-frequency position of the primary synchronization signal and the ID within the cell group;

[0017] Detection of PSS yields:

[0018] d PSS (n) = 1-2x(m)

[0019]

[0020] 0≤n<127

[0021] in,

[0022] x(i+7)=(x(i+4)+x(i))mod 2

[0023] [x(6)x(5)x(4)x(3)x(2)x(1)x(0)]=[1110110]

[0024] Where, d PSS(·) is the time-frequency position of the main synchronization signal; m and n are the main synchronization signal detection loop variables; is the ID of the cell group, and its value is {0, 1, 2}; x(i) is the basic sequence generated by PSS;

[0025] Step 1.2, SSS detection;

[0026] Determine the SSS position based on the PSS time-frequency position and obtain:

[0027] d SSS (n) = [1-2x0((n+m0) mod 127)]

[0028] [1-2x1((n+m1)mod127)]

[0029]

[0030] in,

[0031] x0(i+7)=(x0(i+4)+x0(i))mod 2

[0032] x1(i+7)=(x1(i+1)+x1(i))mod 2

[0033] The initial values ​​are set to:

[0034] [x0(6)x0(5)x0(4)x0(3)x0(2)x0(1)x0(0)]=[0000001]

[0035] [x1(6)x1(5)x1(4)x1(3)x1(2)x1(1)x1(0)]=[0000001]

[0036] Where, d SSS (·) is the auxiliary synchronization signal position; m0 and m1 are auxiliary synchronization signal detection loop variables; is the ID of the cell group, which takes the value of {0, 1, ..., 335}; x0 and x1 are the two Gold code sequences required to generate SSS;

[0037] according to and jointly determine the cell ID;

[0038] Step 1.3: Determine the maximum number of SS / PBCH transmissions L within the burst set period based on the frequency deployment range and subcarrier spacing of the 5G NR signal. max ;

[0039] Step 1.4, determine the index of SS / PBCH in a burst set period;

[0040] The SS / PBCH index is determined using the PBCH demodulation reference signal DMRS and its load analysis. The PBCH demodulation reference signal DMRS is:

[0041]

[0042] in,

[0043]

[0044] Where r(·) is the PBCH demodulation reference signal; j is the imaginary unit; c(·) is the pseudo-random sequence; c init The initial value parameters required to generate a pseudo-random sequence; is the cell ID; Parameter used to determine the SS / PBCH index within a burst set period;

[0045] The maximum number of SS / PBCH transmissions in one burst set period is L max There are three cases: 4, 8, and 64. When L max When it is 4 or 8, the SS / PBCH index in a burst set period is Directly determine; when L max When the value is 64, the SS / PBCH index in a burst set period requires 5 bits to determine. The lower 3 bits are determined, and then the 32-bit SS / PBCH information carried by the PBCH load information is analyzed by the protocol. The 32 bits contain the highest 2 bits of the SS / PBCH index. At this time, the SS / PBCH load information is decoded to determine the SS / PBCH index within a burst set period.

[0046] Step 1.5, half-frame number detection;

[0047] The 32-bit SS / PBCH information carried by the PBCH load information carries both the highest 2 bits of the SS / PBCH index and the half-frame number information. The half-frame number is obtained by decoding the 32-bit SS / PBCH information carried by the PBCH load information.

[0048] Step 1.6, determine the SS / PBCH pattern and burst set period;

[0049] The SS / PBCH pattern is determined by the subcarrier spacing of the 5G NR signal. However, when the subcarrier spacing is 30kHz, there are two SS / PBCH patterns, CASE B and CASE C. The SS / PBCH is detected according to the time domain positions indicated by the different patterns of CASE B and CASE C to determine the pattern type. The burst set period is determined by detecting different periods according to the pattern type.

[0050] Step 1.7, frame synchronization;

[0051] Based on the SS / PBCH time-frequency position, the SS / PBCH index within a burst set period, the SS / PBCH half-frame index and transmission period, and the SS / PBCH pattern, the time domain symbol index in a frame of data is determined to determine the time domain position of the frame data and achieve frame synchronization.

[0052] Preferably, in step 2, based on the CP-OFDM system used in the 5G NR signal, after the Doppler frequency shift or the frequency offset generated by the transceiver with a different reference clock, a conjugate operation is used to perform frequency offset estimation, and the frequency offset estimate is obtained as follows:

[0053]

[0054] in,

[0055]

[0056] Where z is the correlation value between the CP sequence and the delay sequence, and the delay D is exactly the number of FFT samples of the OFDM symbol; r n is the sample value of the CP sequence at time n, is the sequence sample value after the CP sequence is delayed by D; S n is the ideal sample value of CP at time n, S n+D is the ideal data sequence sample value after the CP sequence is delayed by D; T s is the sampling time interval of the sample points; Δf is the frequency offset estimation result.

[0057] Preferably, in step 3, after completing carrier synchronization, channel estimation is performed based on the demodulation reference signal provided by each channel type in the 5G NR signal to determine the PBCH demodulation reference signal Y p for:

[0058] Y p =X p H p +n p

[0059] Where, X p H is the pilot data at the original DMRS sent; p is the channel response at the DMRS subcarrier, n p For noise;

[0060] Construct the cost function J(H' p ),get:

[0061] J(H' p )=(Y p -X p H'p ) H (Y p -X p H' p )

[0062] H' p Derivative so that J(H' p )=0, the channel estimate H is determined as:

[0063]

[0064] Channel equalization is performed by dividing the received signal in the frequency domain by the channel estimate.

[0065] Preferably, in step 4, after the channel equalization is completed, the constellation diagram of the 5G NR signal has converged, and a modulation distortion test is performed to generate an ideal signal and compare it with the demodulated signal to determine the modulation distortion test result.

[0066] Preferably, in step 5, a modulation distortion test is performed and the error vector magnitude is calculated, and then the modulation distortion analysis is evaluated using origin offset, quadrature error and gain imbalance evaluation.

[0067] Preferably, the error vector magnitude (EVM) calculation formula is:

[0068]

[0069] Where t is the time index; f is the frequency index; T is the duration of the 5G NR signal; F(i) is the set of subcarriers occupied by the 5G NR signal; Meas(·) is the measurement signal; and Ref(·) is the reference signal.

[0070] Preferably, the origin offset is carrier leakage for 5G NR signals, and is determined by the ratio of subcarrier power 0 to total transmit power;

[0071] The orthogonal error and gain imbalance affect each other. By constructing an error model, we can obtain:

[0072] Meas(t)=g I ×[Ref I (t)+c I ]+j·g Q ×[Ref Q (t)+c Q ]+n(t)

[0073] Where g I 、g Q are all complex numbers, used to indicate the imbalance between I and Q paths; c I 、c Qare all complex numbers, used to represent the real and imaginary parts of the origin offset; n(·) is the noise; Ref I (·) is the reference signal I path; Ref Q (·) is the Q path of the reference signal;

[0074] Since the 5G NR signal is an OFDM signal, the measurement signal and the reference signal are converted from the frequency domain to the time domain. I 、c Q disappears, and the error model becomes:

[0075] F(g I ,g Q )=min{|Meas(t,f)-Ref(t,f)| 2}

[0076] Where F(·) is the cost function; min(·) is the minimum function;

[0077] The orthogonal error and gain imbalance are calculated and determined using the least square method.

[0078] The beneficial technical effects brought about by the present invention are:

[0079] (1) The present invention proposes an intelligent analysis method for 5G NR signal modulation distortion, which realizes the intelligent synchronization of 5G NR signals, avoids the complex parameter configuration of 5G NR signal analysis, and reduces the professional level requirements for operators.

[0080] (2) The present invention proposes an intelligent analysis method for 5G NR signal modulation distortion. By designing a complete set of 5G NR signal modulation distortion test and analysis solutions, high-precision modulation distortion analysis of 5G NR signals is achieved.

[0081] (3) The present invention proposes an intelligent analysis method for 5G NR signal modulation distortion. While performing modulation distortion error (EVM) analysis, a modulation distortion error source model is constructed by analyzing the error source, thereby realizing the testing of modulation distortion parameters such as orthogonal error and gain imbalance, and enriching the dimension of 5G system modulation distortion testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 Flowchart for manually configuring 5G NR modulation analysis.

[0083] Figure 2 This is a flowchart of the intelligent analysis of 5G NR signal modulation distortion in the present invention.

[0084] Figure 3 This is a structural diagram of the synchronous broadcast block.

[0085] Figure 4This is a flowchart of intelligent synchronization detection. DETAILED DESCRIPTION

[0086] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0087] This embodiment proposes a 5G NR signal modulation distortion intelligent analysis method for performing modulation distortion test analysis on baseband IQ data, such as Figure 2 As shown, the following steps are included:

[0088] Step 1, intelligent synchronization detection;

[0089] Perform intelligent synchronization detection on the synchronization broadcast block (SS / PBCH). The synchronization broadcast block (SS / PBCH) includes the primary synchronization signal (PSS), the secondary synchronization signal (SSS) and the physical broadcast channel (PBCH). The position relationship between the three is fixed, such as Figure 3 As shown, the synchronization broadcast block is used for synchronization operations when the base station and the terminal establish a connection. Test instruments such as signal analyzers cannot perform signaling interaction with devices such as base stations. The parameters required for SS / PBCH cannot be obtained by the upper layer. Traditional solutions can only be configured manually. Therefore, this embodiment proposes an intelligent synchronization detection method for SS / PBCH, such as Figure 4 As shown, it specifically includes the following sub-steps:

[0090] Step 1.1: Primary Synchronization Signal (PSS) detection to determine the PSS time-frequency position and cell group ID.

[0091] 5G NR signals provide two synchronization signals: the primary synchronization signal (PSS) and the secondary synchronization signal (SSS). First, detect the primary synchronization signal (PSS) to obtain:

[0092] d PSS (n) = 1-2x(m)

[0093]

[0094] 0≤n<127

[0095] in,

[0096] x(i+7)=(x(i+4)+x(i))mod 2

[0097] [x(6)x(5)x(4)x(3)x(2)x(1)x(0)]=[1110110]

[0098] Where, d PSS (·) is the time-frequency position of the main synchronization signal; m and n are the main synchronization signal detection loop variables; is the ID within the cell group, and its value is {0, 1, 2}; x(i) is the basic sequence generated by PSS.

[0099] Step 1.2, auxiliary synchronization signal detection;

[0100] Since the positional relationship between the PSS, SSS, and PBCH in the SS / PBCH is fixed, the position of the SSS can be determined after the position of the PSS is determined, and the result is:

[0101] d SSS (n) = [1-2x0((n+m0) mod 127)]

[0102] [1-2x1((n+m1)mod127)]

[0103]

[0104] in,

[0105] x0(i+7)=(x0(i+4)+x0(i))mod 2

[0106] x1(i+7)=(x1(i+1)+x1(i))mod 2

[0107] The initial values ​​are set to:

[0108] [x0(6)x0(5)x0(4)x0(3)x0(2)x0(1)x0(0)]=[0000001]

[0109] [x1(6)x1(5)x1(4)x1(3)x1(2)x1(1)x1(0)]=[0000001]

[0110] Where, d SSS (·) is the auxiliary synchronization signal position; m0 and m1 are auxiliary synchronization signal detection loop variables; is the ID of the cell group, which takes the value of {0, 1, …, 335}; x0 and x1 are the two Gold code sequences required to generate SSS.

[0111] From the above formula, we can find that the cell ID has a fixed value. First, the cell group ID is determined by PSS, and then and The cell ID is jointly determined to complete the cell ID detection.

[0112] Since the above detection process only searches for a specific SS / PBCH, for multiple SS / PBCHs, only after determining the current SS / PBCH index can the symbol position of the current SS / PBCH in a frame be determined, and then the frame start position of a frame of 5G NR signal can be determined.

[0113] The determining parameters of the SS / PBCH index include a burst set period, an SS / PBCH pattern, a number of SS / PBCHs, and a half-frame number. The burst set period is used to determine how often the SS / PBCH set is sent, the S / PBCH pattern is used to indicate the time domain arrangement rule of the SS / PBCH, the number of SS / PBCHs is used to indicate the number of SS / PBCHs contained in an SS / PBCH set, and the half-frame number is used to indicate whether the SS / PBCH set is sent in the first half-frame or the second half-frame. Therefore, the SS / PBCH index needs to be determined by determining the above parameters.

[0114] Step 1.3: Determine the maximum number of synchronous broadcast blocks sent within the burst set period, L, based on the frequency deployment range and subcarrier spacing of the 5G NR signal. max .

[0115] Step 1.4, determine the index of SS / PBCH in a burst set period;

[0116] Since the PSS and SSS only contain cell ID information and do not include SS / PBCH index information, while the PBCH demodulation reference signal (DMRS) and its payload contain SS / PBCH index information, the PBCH demodulation reference signal (DMRS) and its payload are used in this embodiment to parse and determine the SS / PBCH index.

[0117] The PBCH demodulation reference signal is:

[0118]

[0119] in,

[0120]

[0121] Where r(·) is the PBCH demodulation reference signal; j is the imaginary unit; c(·) is the pseudo-random sequence; c init The initial value parameters required to generate a pseudo-random sequence; is the cell ID; It is a parameter used to determine the index of SS / PBCH in a burst set period.

[0122] The maximum number of SS / PBCH transmissions in one burst set period is L max There are three cases: 4, 8, and 64. When L max When it is 4 or 8, the SS / PBCH index in a burst set period is Directly determine; when L max When the value is 64, the SS / PBCH index in a burst set period requires 5 bits to determine. Only the lower 3 bits can be determined. Then, the protocol analyzes the 32-bit SS / PBCH information carried by the PBCH payload information. The 32 bits contain the highest 2 bits of the SS / PBCH index. Therefore, by decoding the SS / PBCH payload information, the SS / PBCH index within a burst set period can be determined.

[0123] Step 1.5, half-frame number detection;

[0124] The 32-bit SS / PBCH information carried by the PBCH load information carries both the highest 2 bits of the SS / PBCH index and the half-frame number information. The half-frame number is obtained by decoding the 32-bit SS / PBCH information carried by the PBCH load information.

[0125] Step 1.6, determine the SS / PBCH pattern and burst set period;

[0126] The SS / PBCH pattern is determined by the subcarrier spacing of the 5G NR signal. However, when the subcarrier spacing is 30kHz, there are two SS / PBCH patterns, CASE B and CASE C. The pattern type can be determined by detecting the time domain positions of the different pattern indications of CASE B and CASE C. The burst set period can be determined by detecting different periods according to the pattern type.

[0127] Step 1.7, frame synchronization;

[0128] The index of SS / PBCH in a burst set period is determined according to the SS / PBCH time-frequency position, and then the half-frame index and transmission period of SS / PBCH are determined. The time domain symbol index of SS / PBCH in a frame of data is determined by SS / PBCH pattern, thereby obtaining the time domain symbol index of SS / PBCH in a frame of data, and then determining the specific time domain position of the frame data to achieve frame synchronization.

[0129] Step 2: carrier synchronization;

[0130] Since the 5G NR signal uses the CP-OFDM system, CP is the cyclic prefix, which is a guard interval formed by copying the last part of the OFDM symbol to the front. The two segments of data are completely copied, so the second segment of data can be considered as a delay of the first segment of data. After the Doppler frequency shift or the frequency offset generated by the transceiver with different reference clocks, the conjugate operation is used to estimate the frequency offset, and the frequency offset estimate is obtained as follows:

[0131]

[0132] in,

[0133]

[0134] Where z is the correlation value between the CP sequence and the delay sequence, and the delay D is exactly the number of FFT samples of the OFDM symbol; r n is the sample value of the CP sequence at time n, is the sequence sample value after the CP sequence is delayed by D; S n is the ideal sample value of CP at time n, S n+D is the ideal data sequence sample value after the CP sequence is delayed by D; T s is the sampling time interval of the sample points; Δf is the frequency offset estimation result.

[0135] Step 3: channel estimation and equalization;

[0136] After completing the carrier synchronization, due to the non-ideal amplitude and phase characteristics of the transmitting equipment in the broadband band, the constellation diagram does not converge at this time, and the modulation distortion test cannot be performed. Channel estimation and equalization are required. Each channel type in the 5G NR signal provides its own demodulation reference signal, such as the broadcast channel demodulation reference signal (PBCH DMRS), the physical shared channel demodulation reference signal (PDSCH DMRS), etc. These signals can be used for channel estimation. Therefore, channel estimation is performed based on the demodulation reference signal provided by each channel type in the 5G NR signal to determine the PBCH demodulation reference signal Y p for:

[0137] Y p =X p H p +n p

[0138] Where, X p H is the pilot data at the original DMRS sent; p is the channel response at the DMRS subcarrier, n p For noise.

[0139] Construct the cost function J(H' p ),get:

[0140] J(H' p )=(Y p -X p H' p ) H (Y p -X p H' p )

[0141] H' p Derivative so that J(H' p )=0, the channel estimate H is determined as:

[0142]

[0143] Channel equalization is performed by dividing the received signal in the frequency domain by the channel estimate.

[0144] Step 4: Reference signal generation;

[0145] After channel equalization is completed, the constellation diagram of the 5G NR signal has converged. However, to test the modulation distortion, it is necessary to generate an ideal signal. The modulation distortion test result can be obtained by comparing the demodulated signal with the ideal signal.

[0146] Step 5, modulation distortion analysis;

[0147] Error vector magnitude (EVM) is the most critical metric for modulation distortion testing. Its results comprehensively reflect the degree of modulation distortion. Any suboptimal modulation in the transmitter will result in a deterioration in EVM. Therefore, test instruments like signal analyzers require a more detailed evaluation system for modulation distortion analysis. This system includes results such as origin offset, quadrature error, and gain imbalance.

[0148] In this embodiment, a modulation distortion test is performed and an error vector magnitude (EVM) is calculated. The EVM calculation formula is:

[0149]

[0150] Where t is the time index; f is the frequency index; T is the duration of the 5G NR signal; F(i) is the set of subcarriers occupied by the 5G NR signal; Meas(·) is the measurement signal; and Ref(·) is the reference signal.

[0151] Modulation distortion analysis is evaluated using origin offset, quadrature error, and gain imbalance. For 5G NR signals, origin offset represents carrier leakage and is determined by the ratio of subcarrier 0 power to total transmit power. Quadrature error and gain imbalance, however, affect each other and are difficult to determine. In this embodiment, an error model is constructed to obtain the following:

[0152] Meas(t)=g I ×[Ref I (t)+c I ]+j·g Q ×[Ref Q (t)+c Q ]+n(t)

[0153] Where g I 、g Q are all complex numbers, used to indicate the imbalance between I and Q paths; c I 、c Qare all complex numbers, used to represent the real and imaginary parts of the origin offset; n(·) is the noise; Ref I (·) is the reference signal I path; Ref Q (·) is the Q path of the reference signal.

[0154] Since the 5G NR signal is an OFDM signal, the measurement signal and the reference signal are converted from the frequency domain to the time domain. I 、c Q disappears, and the error model changes from a quaternary equation to a binary equation:

[0155] F(g I ,g Q )=min{|Meas(t,f)-Ref(t,f)| 2}

[0156] Where F(·) is the cost function and min(·) is the minimum function.

[0157] The quadrature error and gain imbalance are calculated and determined using the least square method in the prior art.

[0158] Thus, the method of the present invention proposes an intelligent synchronization method for 5G NR signals. By automatically detecting parameters such as cell ID, synchronization broadcast block time-frequency position, transmission period, and half-frame offset, it solves the problem of complex synchronization configuration parameter settings for 5G-related personnel and reduces the operational requirements for 5G testers. At the same time, the method of the present invention also proposes a complete set of 5G signal modulation distortion analysis test solutions. With the acquisition of IQ data as input, it covers the complete process of frame synchronization, carrier synchronization, channel estimation, channel equalization, reference signal generation, parameter calculation, etc., meeting the modulation distortion test requirements of test instruments, enriching the dimensions of 5G system modulation distortion testing, and realizing high-precision analysis of 5G NR signal modulation distortion.

[0159] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0160] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A 5G NR signal modulation distortion intelligent analysis method, characterized in that: Used to perform modulation distortion test analysis on baseband IQ data, including the following steps: Step 1, intelligent synchronization detection; Step 2: carrier synchronization; Step 3: channel estimation and equalization; Step 4: Reference signal generation; Step 5: Modulation distortion analysis.

2. The 5G NR signal modulation distortion intelligent analysis method according to claim 1, characterized in that: In step 1, intelligent synchronization detection is performed on the SS / PBCH. The SS / PBCH includes the PSS, SSS, and PBCH, and the positional relationship between the three is fixed. The SS / PBCH index includes a burst set period, an SS / PBCH pattern, the number of SS / PBCHs, and a half-frame number. The burst set period is used to determine how often the SS / PBCH set is sent, the SS / PBCH pattern is used to indicate the time domain arrangement rule of the SS / PBCH, the number of SS / PBCHs is used to indicate the number of SS / PBCHs contained in an SS / PBCH set, and the half-frame number is used to indicate the sending position of the SS / PBCH set.

3. The 5G NR signal modulation distortion intelligent analysis method according to claim 2, characterized in that: The intelligent synchronization detection includes the following sub-steps: Step 1.1: PSS detection to determine the time-frequency position of the primary synchronization signal and the ID within the cell group; Detection of PSS yields: d PSS (n)=1-2x(m) 0≤n＜127 in, x(i+7)=(x(i+4)+x(i))mod 2 [x(6)x(5)x(4)x(3)x(2)x(1)x(0)]=[1110110] Where, d PSS (·) is the time-frequency position of the main synchronization signal; m and n are the main synchronization signal detection loop variables; is the ID of the cell group, and its value is {0, 1, 2}; x(i) is the basic sequence generated by PSS; Step 1.2, SSS detection; Determine the SSS position based on the PSS time-frequency position and obtain: d SSS (n)=[1-2x0((n+m0)mod127)] [1-2x1((n+m1)mod127)] in, x0(i+7)=(x0(i+4)+x0(i))mod 2 x1(i+7)=(x1(i+1)+x1(i))mod 2 The initial values ​​are set to: [x0(6)x0(5)x0(4)x0(3)x0(2)x0(1)x0(0)]=[0000001] [x1(6)x1(5)x1(4)x1(3)x1(2)x1(1)x1(0)]=[0000001] Where, d SSS (·) is the auxiliary synchronization signal position; m0 and m1 are auxiliary synchronization signal detection loop variables; is the ID of the cell group, which takes the value of {0, 1, ..., 335}; x0 and x1 are the two Gold code sequences required to generate SSS; according to and jointly determine the cell ID; Step 1.3: Determine the maximum number of SS / PBCH transmissions L within the burst set period based on the frequency deployment range and subcarrier spacing of the 5G NR signal. max ; Step 1.4, determine the index of SS / PBCH in a burst set period; The SS / PBCH index is determined using the PBCH demodulation reference signal DMRS and its load analysis. The PBCH demodulation reference signal DMRS is: in, Where r(·) is the PBCH demodulation reference signal; j is the imaginary unit; c(·) is the pseudo-random sequence; c init The initial value parameters required to generate a pseudo-random sequence; is the cell ID; Parameter used to determine the SS / PBCH index within a burst set period; The maximum number of SS / PBCH transmissions in one burst set period is L max There are three cases: 4, 8, and 64. When L max When it is 4 or 8, the SS / PBCH index in a burst set period is Directly determine; when L max When the value is 64, the SS / PBCH index in a burst set period requires 5 bits to determine. The lower 3 bits are determined, and then the 32-bit SS / PBCH information carried by the PBCH load information is analyzed by the protocol. The 32 bits contain the highest 2 bits of the SS / PBCH index. At this time, the SS / PBCH load information is decoded to determine the SS / PBCH index within a burst set period. Step 1.5, half-frame number detection; The 32-bit SS / PBCH information carried by the PBCH load information carries both the highest 2 bits of the SS / PBCH index and the half-frame number information. The half-frame number is obtained by decoding the 32-bit SS / PBCH information carried by the PBCH load information. Step 1.6, determine the SS / PBCH pattern and burst set period; The SS / PBCH pattern is determined by the subcarrier spacing of the 5G NR signal. However, when the subcarrier spacing is 30kHz, there are two SS / PBCH patterns, CASE B and CASE C. The SS / PBCH is detected according to the time domain positions indicated by the different patterns of CASE B and CASE C to determine the pattern type. The burst set period is determined by detecting different periods according to the pattern type. Step 1.7, frame synchronization; Based on the SS / PBCH time-frequency position, the SS / PBCH index within a burst set period, the SS / PBCH half-frame index and transmission period, and the SS / PBCH pattern, the time domain symbol index in a frame of data is determined to determine the time domain position of the frame data and achieve frame synchronization.

4. The 5G NR signal modulation distortion intelligent analysis method according to claim 1, wherein: In step 2, based on the CP-OFDM system used in the 5G NR signal, after the Doppler frequency shift or the frequency offset generated by the transceiver with a different reference clock, the frequency offset is estimated using a conjugate operation, and the frequency offset estimate is obtained as follows: in, Where z is the correlation value between the CP sequence and the delay sequence, and the delay D is exactly the number of FFT samples of the OFDM symbol; r n is the sample value of the CP sequence at time n, is the sequence sample value after the CP sequence is delayed by D; S n is the ideal sample value of CP at time n, S n+D is the ideal data sequence sample value after the CP sequence is delayed by D; T s is the sampling time interval of the sample points; Δf is the frequency offset estimation result.

5. The 5G NR signal modulation distortion intelligent analysis method according to claim 1, wherein: In step 3, after completing carrier synchronization, channel estimation is performed based on the demodulation reference signal provided by each channel type in the 5G NR signal to determine the PBCH demodulation reference signal Y p for: Y p =X p H p +n p Where, X p H is the pilot data at the original DMRS sent; p is the channel response at the DMRS subcarrier, n p For noise; Construct the cost function J(H' p ),get: J(H' p )=(Y p -X p H' p ) H (Y p -X p H' p ) H' p Derivative so that J(H' p )=0, the channel estimate H is determined as: Channel equalization is performed by dividing the received signal in the frequency domain by the channel estimate.

6. The 5G NR signal modulation distortion intelligent analysis method according to claim 1, wherein: In step 4, after channel equalization is completed, the constellation diagram of the 5G NR signal has converged, and a modulation distortion test is performed to generate an ideal signal and compare it with the demodulated signal to determine the modulation distortion test result.

7. The 5G NR signal modulation distortion intelligent analysis method according to claim 1, wherein: In step 5, a modulation distortion test is performed and the error vector magnitude is calculated, and then the modulation distortion analysis is evaluated using origin offset, orthogonal error, and gain imbalance evaluation.

8. The 5G NR signal modulation distortion intelligent analysis method according to claim 7, characterized in that: The error vector magnitude (EVM) calculation formula is: Where t is the time index; f is the frequency index; T is the duration of the 5G NR signal; F(i) is the set of subcarriers occupied by the 5G NR signal; Meas(·) is the measurement signal; and Ref(·) is the reference signal.

9. The 5G NR signal modulation distortion intelligent analysis method according to claim 7, wherein: The origin offset is carrier leakage for 5G NR signals and is determined by the ratio of subcarrier 0 power to total transmit power. The orthogonal error and gain imbalance affect each other. By constructing an error model, we can obtain: Meas(t)=g I ×[Ref I (t)+c I ]+j·g Q ×[Ref Q (t)+c Q ]+n(t) Where g I 、g Q are all complex numbers, used to indicate the imbalance between I and Q paths; c I 、c Q are all complex numbers, used to represent the real and imaginary parts of the origin offset; n(·) is the noise; Ref I (·) is the reference signal I path; Ref Q (·) is the Q path of the reference signal; Since the 5G NR signal is an OFDM signal, the measurement signal and the reference signal are converted from the frequency domain to the time domain. I 、c Q disappears, and the error model becomes: F(g I ,g Q )=min{|Meas(t,f)-Ref(t,f)| 2 } Where F(·) is the cost function; min(·) is the minimum function; The orthogonal error and gain imbalance are calculated and determined using the least square method.

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