A joint compensation design method and device for a 5G NTN scenario

Abstract

The application relates to a joint compensation design method and device for a 5G NTN scene. The method comprises the following steps: receiving a time-domain OFDM signal, calculating a first frequency offset estimation value by using the time-domain autocorrelation characteristics of a cyclic prefix and corresponding tail data; acquiring phase de-pre-compensation parameters, including a pre-compensation frequency value and the cyclic prefix length and data length of each OFDM symbol; performing joint compensation on the time-domain OFDM signal according to the first frequency offset estimation value, the phase de-pre-compensation parameters and a current sampling point index, combining Doppler frequency offset compensation and phase de-pre-compensation into the same exponential operation to obtain a joint-compensated time-domain signal; and performing a cyclic prefix removal operation on the joint-compensated time-domain signal to obtain a to-be-transformed signal. The method can effectively eliminate a huge Doppler frequency offset, optimize the overall calculation complexity, reduce the storage requirement of the system, and significantly shorten the 5G NTN scene Low PHY uplink processing time delay.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a joint compensation design method and apparatus for a 5GNTN scenario. Background Technology

[0002] With the development of 5G non-terrestrial network technology, low Earth orbit (LEO) satellite communication has become an important means of expanding coverage. This technology is characterized by the high-speed motion of satellites relative to the ground, resulting in Doppler shifts of up to hundreds of kilohertz in the Ka band or Sub-6 GHz band. This characteristic places additional frequency offset suppression requirements on the design of the 5G NTN uplink low physical layer (LowPHY).

[0003] In terrestrial 5G systems, due to the relatively small Doppler frequency offset, the typical processing flow at the LowPHY receiver includes: cyclic prefix removal, calculation of received signal strength indication, automatic gain control, phase pre-compensation, fast Fourier transform, and FFT shifting. The phase pre-compensation module is used to compensate for phase rotation introduced by precoding or beamforming at the transmitter, but this module itself does not handle large-scale Doppler frequency offsets. This process is well-suited to terrestrial cellular communication environments.

[0004] However, when 5G systems are directly applied to NTN scenarios, the traditional LowPHY process has obvious technical defects. The huge Doppler frequency offset will cause inter-carrier interference and phase rotation, which cannot be eliminated by the original phase decompensation alone. Summary of the Invention

[0005] Based on this, it is necessary to provide a joint compensation design method and device for 5GNTN scenarios that can effectively eliminate huge Doppler frequency offset, optimize overall computational complexity, reduce system storage requirements, and thus significantly shorten the uplink processing latency of LowPHY in 5GNTN scenarios, in order to address the above-mentioned technical problems.

[0006] A joint compensation design method for a 5GNTN scenario, the method comprising: Receive the time-domain OFDM signal, and use the time-domain autocorrelation characteristics of the cyclic prefix and the corresponding tail data of the OFDM symbol to calculate the first frequency offset estimate for large frequency offset acquisition; Obtain the phase solution pre-compensation parameters, which include the pre-compensation frequency value, the cyclic prefix length, and the data length for each OFDM symbol; Based on the first frequency offset estimate, the phase decompensation parameters, and the current sampling point index, the time-domain OFDM signal is jointly compensated. The joint compensation combines the Doppler frequency offset compensation and the phase decompensation into the same exponential operation to obtain the time-domain signal after joint compensation. Perform a cyclic prefix removal operation on the jointly compensated time-domain signal to obtain the signal to be transformed.

[0007] A joint compensation design device for a 5GNTN scenario, the device comprising: The receiving module is used to receive time-domain OFDM signals; The frequency offset estimation module is used to calculate the first frequency offset estimate for large frequency offset capture by utilizing the time-domain autocorrelation characteristics of the cyclic prefix and the corresponding tail data of OFDM symbols. The parameter acquisition module is used to acquire the phase solution pre-compensation parameters, which include the pre-compensation frequency value, the cyclic prefix length and the data length of each OFDM symbol; The joint compensation module is used to perform joint compensation on the time-domain OFDM signal based on the first frequency offset estimate, the phase decompensation parameters, and the current sampling point index. The joint compensation combines the Doppler frequency offset compensation and the phase decompensation into the same exponential operation to obtain the time-domain signal after joint compensation. The decyclic prefix module is used to perform a decyclic prefix operation on the jointly compensated time-domain signal to obtain the signal to be transformed.

[0008] The aforementioned joint compensation design method and apparatus for a 5GNTN scenario first obtains a first frequency offset estimate by receiving a time-domain OFDM signal and utilizing the time-domain autocorrelation characteristics of the cyclic prefix. This directly captures and suppresses a large-scale Doppler frequency offset in the time domain, overcoming the limitation of the original phase decompensation module in handling large frequency offsets. Based on this, phase decompensation parameters are further obtained, and Doppler frequency offset compensation and phase decompensation are merged into a single exponential operation for joint compensation. Finally, a cyclic prefix removal operation is performed. By merging two originally independent exponential operations into a single exponential operation, the redundancy of multipliers, the overhead of storing intermediate results, and the serial processing delay caused by two independent complex multiplications in the cascaded scheme are avoided. This effectively eliminates large Doppler frequency offsets while significantly reducing storage resource consumption, multiplier requirements, and shortening the uplink processing latency of the low physical layer in the 5GNTN scenario. Attached Figure Description

[0009] Figure 1 This is a flowchart illustrating a joint compensation design method for a 5GNTN scenario in one embodiment. Figure 2 This is a structural block diagram of a joint compensation design device for a 5GNTN scenario in one embodiment. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0011] In one embodiment, such as Figure 1 As shown, a joint compensation design method for a 5G NTN scenario is provided, including the following steps: Step 1: Receive the time-domain OFDM signal, and use the time-domain autocorrelation characteristics of the cyclic prefix and the corresponding tail data of the OFDM symbol to calculate the first frequency offset estimate for large frequency offset acquisition.

[0012] Time-domain OFDM signals are time-domain orthogonal frequency division multiplexing signals of the uplink shared channel - PUSCH - for low-Earth orbit satellites not connected to terrestrial networks. An OFDM symbol consists of an effective portion (length...). ) and cyclic prefix (length) The symbol header is composed of . The cyclic prefix -CP is copied from the tail of the valid part, therefore the symbol header is composed of . Each sample corresponds to the end of the symbol. Each sample is identical. If a frequency offset Δf exists, there is a stable phase rotation between the corresponding samples in the CP segment and the tail segment. Multiplying the two by their conjugates and summing them yields the correlation quantity, the phase of which can be used to estimate the frequency offset.

[0013] In practical system simulations, frequency offset estimation is typically avoided by extracting the CP signal of the first OFDM symbol. This is because the initial OFDM symbol experiences channel instability and uneven noise statistics, which can disturb the phase fluctuations on the CP sample and affect the calculation accuracy. To further improve the accuracy of frequency offset estimation, we use the CP of the middle symbol from symbols 0 to 13 for frequency offset estimation, that is, any one of the 4th to 10th orthogonal frequency division multiplexing symbols in the slot. Generally, the CP data of the 7th symbol is extracted for frequency offset estimation calculation.

[0014] Step 2: Obtain the phase solution pre-compensation parameters, which include the pre-compensation frequency value, the cyclic prefix length, and the data length of each OFDM symbol.

[0015] In 5G systems, the phase decompensation module needs to perform phase rotation on each OFDM symbol to compensate for phase changes introduced by precoding or beamforming at the transmitter. Its parameters include the precompensation frequency value. and the cyclic prefix length of each OFDM symbol and data length The data length satisfies the following: , ( These parameters are used to calculate the cumulative phase of the phase solution pre-compensation, i.e., the cumulative number of sampling points from the first OFDM symbol to the current symbol. Obtaining these parameters is the basis for subsequent joint compensation calculations.

[0016] Step 3: Based on the first frequency offset estimate, the phase decompensation parameters, and the current sampling point index, perform joint compensation on the time-domain OFDM signal. The joint compensation combines Doppler frequency offset compensation and phase decompensation into the same exponential operation to obtain the time-domain signal after joint compensation.

[0017] This application achieves joint compensation by simultaneously reflecting the phase rotation caused by Doppler frequency offset and the accumulated phase required for phase solution pre-compensation in a single exponential function. The phase rotation caused by Doppler frequency offset is related to the sampling point index. The cumulative phase required for phase pre-compensation is proportional to the cumulative symbol length. The jointly compensated signal can directly enter the decyclic prefix operation without intermediate storage or additional multipliers.

[0018] Step 4: Perform a cyclic prefix removal operation on the jointly compensated time-domain signal to obtain the signal to be transformed.

[0019] After joint compensation, the signal has simultaneously completed Doppler frequency offset coarse compensation and phase deprecation pre-compensation. Then, a cyclic prefix removal operation is performed to remove the cyclic prefix portion of each OFDM symbol, resulting in a clean time-domain data block, i.e., the signal to be transformed, ready for FFT transformation. Since the joint compensation has fused the two compensations, the cyclic prefix removal operation does not need to consider phase rotation issues, making the process simple and efficient.

[0020] In a subsequent embodiment, the first frequency offset estimate for large frequency offset acquisition is calculated using the time-domain autocorrelation characteristics of the cyclic prefix and corresponding tail data of the OFDM symbol, including: Calculate the sum of the conjugate multiplications of the cyclic prefix and the tail data, average the sum of the conjugate multiplications, and map the calculated average phase value to the angle flip value; then map the angle flip value to the true frequency offset value to obtain the first frequency offset estimate.

[0021] Specifically, since the carrier frequency offset phase is consistent in direction on all subcarriers (i.e., consistent in sign), while the noise phase is random (i.e., random in sign), coherent accumulation can significantly suppress noise and achieve high processing gain.

[0022] In a subsequent embodiment, the sum of the conjugate multiplications of the loop prefix and the tail data is calculated as follows: ; in, In order to receive signals, The length of the cyclic prefix. The conjugate of the tail data samples. The sampling point number, The number of points in the FFT. The amplitude at each subcarrier phase, This is the first frequency offset estimate. The sampling period.

[0023] In a subsequent embodiment, averaging the conjugate multiplications to map the calculated average phase value to an angle flip value includes: The average of the sums of conjugate multiplications is: ; The calculated average phase value is mapped to the angle flip value as follows: ; in, The sampling rate of the signal.

[0024] Specifically, the impact of noise on phase estimation is further reduced by averaging, thereby improving the stability of frequency offset estimation.

[0025] In a subsequent embodiment, the angle flip value is then mapped to the true frequency offset value to obtain a first frequency offset estimate, including: Then, the angle-flipped values ​​are mapped to the true frequency offset values ​​to obtain the first frequency offset estimate: ; in, The sampling rate of the signal. This is the value for the angle flip.

[0026] Specifically, by establishing a quantitative mapping relationship between phase difference and actual frequency offset, the conversion from phase observation value to frequency offset estimate value is realized.

[0027] In a subsequent embodiment, when the phase decompensation is downlink precompensation, both the phase factor of the Doppler frequency offset compensation and the phase factor of the phase decompensation are in negative exponential form, and the exponential parameter of the joint compensation is the sum of the exponential parameter of the Doppler frequency offset compensation and the exponential parameter of the phase decompensation. When the phase decompensation is uplink decompensation, the phase factor of the Doppler frequency offset compensation is in negative exponential form, the phase factor of the phase decompensation is in positive exponential form, and the exponential parameter of the joint compensation is the exponential parameter of the Doppler frequency offset compensation minus the exponential parameter of the phase decompensation.

[0028] Specifically, during downlink pre-compensation, the phase factor for Doppler frequency offset compensation is: The downlink pre-compensation phase factor is Both are in negative exponential form, and the exponent parameter of the product is the sum of the two. Therefore, the exponent parameter in the joint compensation formula is taken as "". The form, with a negative sign before the whole, corresponds to the minus sign in the formula. When performing uplink pre-compensation, the phase factor for phase pre-compensation is in positive exponential form. After multiplying by the negative exponent of Doppler compensation, the exponent parameter becomes the difference between the two. Therefore, the exponent parameter in the joint compensation formula is taken as "". The above distinction ensures that joint compensation can be applied to both downlink pre-compensation and uplink pre-compensation scenarios simultaneously.

[0029] In a subsequent embodiment, the joint compensation combines Doppler frequency offset compensation and phase deprecation pre-compensation into a single exponential operation to obtain the jointly compensated time-domain signal, including: The joint compensation combines Doppler frequency offset compensation and phase decompensation into a single exponential operation, resulting in the following time-domain signal after joint compensation: ; in, The first in the time-domain OFDM signal One sampling point, For the first The length of the data portion of each OFDM symbol, This is the first frequency offset estimate. The index number of the time-domain sampling point. For the pre-compensated frequency value, For the first The length of the cyclic prefix of OFDM symbols, The sampling rate of the signal. This is the cumulative index for OFDM symbols.

[0030] Specifically, in this way, each time-domain sampling point only needs to perform a complex multiplication once to complete both compensations simultaneously, significantly reducing the amount of computation.

[0031] In a later embodiment, satisfy: ; in, The number of FFT points.

[0032] Specifically, the first OFDM symbol has no leading data, and its data portion has a length of 0, containing only a cyclic prefix; starting from the second OFDM symbol, the data portion length of each symbol is equal to the number of FFT points. This definition ensures the correctness of the cumulative sum calculation in the joint compensation formula.

[0033] In a subsequent embodiment, the index of the time-domain sampling points is segmented as follows: ; to The sampling point range corresponding to the first OFDM symbol, where ; to Corresponding to the The sampling point range of each OFDM symbol, where .

[0034] Specifically, the sampling point index is defined. The mapping relationship between OFDM symbol numbers and the OFDM symbol sequence number. Indicates the preceding The total number of sampling points for OFDM symbols, each symbol containing a cyclic prefix and valid data. For the first symbol ( ), sampling points From 0 to For the first a symbol ( ), sampling points from arrive This ensures the cumulative sum in the joint compensation formula. It can accurately reflect the cumulative phase of the symbol to which the current sampling point belongs.

[0035] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0036] In one embodiment, such as Figure 2 As shown, a joint compensation design device for a 5GNTN scenario is provided, comprising: Receiver module 202 is used to receive time-domain OFDM signals; The frequency offset estimation module 204 is used to calculate the first frequency offset estimate for large frequency offset capture by utilizing the time-domain autocorrelation characteristics of the cyclic prefix and the corresponding tail data of OFDM symbols. The parameter acquisition module 206 is used to acquire phase solution pre-compensation parameters, which include pre-compensation frequency values, cyclic prefix length and data length of each OFDM symbol; The joint compensation module 208 is used to perform joint compensation on the time-domain OFDM signal based on the first frequency offset estimate, the phase decompensation parameters, and the current sampling point index. The joint compensation combines Doppler frequency offset compensation and phase decompensation into the same exponential operation to obtain the time-domain signal after joint compensation. The cyclic prefix removal module 210 is used to perform a cyclic prefix removal operation on the jointly compensated time-domain signal to obtain the signal to be transformed.

[0037] Specific limitations regarding the joint compensation design device for a 5GNTN scenario can be found in the limitations of the joint compensation design method for a 5GNTN scenario described above, and will not be repeated here. Each module in the aforementioned joint compensation design device for a 5GNTN scenario can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0038] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A joint compensation design method for 5G NTN scenarios, characterized in that, The method includes: Receive the time-domain OFDM signal, select the cyclic prefix of any symbol from the 4th to the 10th orthogonal frequency division multiplexing symbol in the time slot, and use the time-domain autocorrelation characteristics of the cyclic prefix of the OFDM symbol and the corresponding tail data to calculate the first frequency offset estimate for large frequency offset capture. Obtain the phase solution pre-compensation parameters, which include the pre-compensation frequency value, the cyclic prefix length, and the data length of each OFDM symbol; Based on the first frequency offset estimate, the phase decompensation parameters, and the current sampling point index, the time-domain OFDM signal is jointly compensated. The joint compensation combines Doppler frequency offset compensation and phase decompensation into the same exponential operation to obtain the jointly compensated time-domain signal. The joint compensation is performed in the time domain on a sampling point basis. It is achieved by simultaneously reflecting the phase rotation caused by Doppler frequency offset and the accumulated phase required for phase decompensation in a single exponential function. Each time-domain sampling point only needs to perform one complex multiplication to simultaneously complete Doppler frequency offset compensation and phase decompensation, without the need for intermediate storage. Perform a cyclic prefix removal operation on the jointly compensated time-domain signal to obtain the signal to be transformed; Joint compensation combines Doppler frequency offset compensation and phase decompensation into a single exponential operation, resulting in a jointly compensated time-domain signal, including: The joint compensation combines Doppler frequency offset compensation and phase decompensation into a single exponential operation, resulting in a time-domain signal after joint compensation. in, The first in the time-domain OFDM signal One sampling point, For the first The length of the data portion of each OFDM symbol, This is the first frequency offset estimate. The index number of the time-domain sampling point. For the pre-compensated frequency value, For the first The length of the cyclic prefix of OFDM symbols, The sampling rate of the signal. This is the cumulative index for OFDM symbols.

2. The method according to claim 1, characterized in that, By utilizing the time-domain autocorrelation characteristics of the cyclic prefix and corresponding tail data of OFDM symbols, the first frequency offset estimate for large frequency offset acquisition is calculated, including: Calculate the sum of the conjugate multiplications of the cyclic prefix and the tail data, average the sum of the conjugate multiplications, and map the calculated average phase value to the angle flip value; then map the angle flip value to the true frequency offset value to obtain the first frequency offset estimate.

3. The method according to claim 2, characterized in that, The sum of the conjugate multiplications of the loop prefix and the tail data is calculated as follows: in, In order to receive signals, The length of the cyclic prefix. The conjugate of the tail data samples. The sampling point number, The number of points in the FFT. The amplitude at each subcarrier phase, This is the first frequency offset estimate. The sampling period.

4. The method according to claim 3, characterized in that, The average of the conjugate multiplications is calculated and then mapped to an angle flip value, including: The average of the sums of the conjugate multiplications is: mean_ ; Map the calculated average phase value to the angle flip value. Angle_phi=angle( )= in, The sampling rate of the signal.

5. The method according to claim 3, characterized in that, The angle flip value is then mapped to the true frequency offset value to obtain the first frequency offset estimate, including: The angle flip value is then mapped to the true frequency offset value to obtain the first frequency offset estimate. in, The sampling rate of the signal. This is the value for the angle flip.

6. The method according to claim 1, characterized in that, The joint compensation process includes: When the phase decompensation is downlink precompensation, both the phase factor of Doppler frequency offset compensation and the phase factor of phase decompensation are in negative exponential form, and the exponential parameter of joint compensation is the sum of the exponential parameter of Doppler frequency offset compensation and the exponential parameter of phase decompensation. When the phase decompensation is uplink decompensation, the phase factor of the Doppler frequency offset compensation is in negative exponential form, the phase factor of the phase decompensation is in positive exponential form, and the exponential parameter of the joint compensation is the exponential parameter of the Doppler frequency offset compensation minus the exponential parameter of the phase decompensation.

7. The method according to claim 6, characterized in that, The satisfy: in, The number of FFT points.

8. The method according to claim 6, characterized in that, The index of the time-domain sampling points is segmented as follows: to The sampling point range corresponding to the first OFDM symbol, where , Indicates the preceding Total number of sampling points for OFDM symbols; to Corresponding to the The sampling point range of each OFDM symbol, where .

9. A joint compensation design device for 5G NTN scenarios, characterized in that, The device includes: The receiving module is used to receive time-domain OFDM signals and select the cyclic prefix of any one of the 4th to 10th orthogonal frequency division multiplexing symbols in the time slot; The frequency offset estimation module is used to calculate the first frequency offset estimate for large frequency offset capture by utilizing the time-domain autocorrelation characteristics of the cyclic prefix and the corresponding tail data of OFDM symbols. The parameter acquisition module is used to acquire phase solution pre-compensation parameters, which include pre-compensation frequency values, cyclic prefix length, and data length for each OFDM symbol. The joint compensation module is used to perform joint compensation on the time-domain OFDM signal based on the first frequency offset estimate, the phase decompensation parameters, and the current sampling point index. The joint compensation combines Doppler frequency offset compensation and phase decompensation into a single exponential operation to obtain the jointly compensated time-domain signal, including: The joint compensation combines Doppler frequency offset compensation and phase decompensation into a single exponential operation, resulting in a time-domain signal after joint compensation. in, The first in the time-domain OFDM signal One sampling point, For the first The length of the data portion of each OFDM symbol, This is the first frequency offset estimate. The index number of the time-domain sampling point. For the pre-compensated frequency value, For the first The length of the cyclic prefix of OFDM symbols, The sampling rate of the signal. The cumulative index is used for OFDM symbols; wherein, the joint compensation is performed in the time domain on a sampling point basis, and is achieved by simultaneously reflecting the phase rotation caused by Doppler frequency offset and the cumulative phase required for phase decompensation in a single exponential function. Each time-domain sampling point only needs to perform one complex multiplication to simultaneously complete Doppler frequency offset compensation and phase decompensation, without the need for intermediate storage. The cyclic prefix removal module is used to perform a cyclic prefix removal operation on the jointly compensated time-domain signal to obtain the signal to be transformed.

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