Channel estimation and equalization method suitable for double-satellite cooperative power enhancement

Abstract

The invention discloses a channel estimation and equalization method suitable for double-satellite cooperative power enhancement, and the method comprises the steps: firstly, designing a pilot frequency pattern which is suitable for estimating two-satellite links at the same time in a double-satellite cooperative transmission scene; based on the pilot pattern, an LS-DFT-based channel estimation algorithm suitable for a scene with an ultra-low signal-to-noise ratio of a single-satellite link is designed, and the noise influence is greatly reduced. Finally, a channel equalization algorithm based on double-star link channel response weighted merging is designed, and the demodulation performance of double-star synthetic signals is improved. According to the invention, the problem that the error of the terminal side channel estimation and equalization algorithm is large due to the low signal-to-noise ratio of a single-satellite link in a double-satellite cooperative power enhancement transmission scene is solved.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically a channel estimation and equalization method suitable for dual-satellite cooperative power enhancement. Background Technology

[0002] In recent years, satellite mobile communication technologies, represented by direct satellite connections between mobile phones and satellites, have experienced rapid development. However, limited by the relatively low gain of mobile phone antennas and the extremely high link loss between satellite and ground, current direct satellite connections can only support low-speed services such as voice and SMS, making it difficult to meet the ever-increasing demand for communication speeds. To improve the cost of satellite-to-ground links, AST SpaceMobile used an ultra-low satellite orbit combined with an ultra-large phased array antenna, achieving a satellite-to-ground transmission rate of 14 Mbps. However, limited by antenna manufacturing costs and rocket launch capacity, the area of ​​ultra-large phased array antennas cannot be continuously increased. Therefore, the ultra-large phased array antenna technology route faces technical bottlenecks.

[0003] With the development and construction of large-scale satellite constellations, the number of satellites within the visible range of future terminals can reach dozens. Therefore, terrestrial MIMO technology can be introduced into satellite communication systems, allowing terminals to jointly receive signals from multiple satellites, thereby improving the received signal power. Multi-satellite cooperative power enhancement transmission technology has become a strong candidate for improving the budget of satellite-to-ground links. Multi-satellite cooperative power enhancement transmission technology requires rigorous channel measurement and feedback to ensure link stability. However, different satellite-to-ground links have different channel characteristics, and using the same pilot scheme will cause severe interference. Furthermore, the low signal-to-noise ratio of single-satellite links leads to large errors in channel estimation and equalization results, making it difficult to meet the requirements of multi-satellite cooperative transmission. Therefore, it is necessary to design channel estimation and equalization schemes for multi-satellite cooperative power enhancement transmission scenarios. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a channel estimation and equalization method suitable for dual-satellite coordinated power enhancement. It is applicable to terminal-side channel estimation and equalization in single-satellite link scenarios with low signal-to-noise ratios, utilizing dual-satellite coordinated power enhancement transmission technology. Specifically, the following technical solution is adopted:

[0005] A channel estimation and equalization method suitable for dual-satellite cooperative power enhancement, the method comprising:

[0006] S1: Satellite 1 and Satellite 2 place pilot signals in their respective resource grids, which are then converted into radio frequency signals through inverse Fourier transform, digital-to-analog conversion, and up-conversion, and transmitted to the terminal.

[0007] S2: The terminal receives the radio frequency signals superimposed on satellite 1 and satellite 2 at the terminal antenna, and obtains the receiver resource grid through down-conversion, sampling and Fourier transform process, and extracts the pilot signals of satellite 1 and satellite 2 on the receiver resource grid;

[0008] S3: The terminal uses the extracted pilot signals of satellite 1 and satellite 2 to estimate the frequency domain response of the two channels respectively through the least squares-discrete Fourier transform channel estimation algorithm;

[0009] S4: The terminal combines the two channel frequency domain responses estimated by LS-DFT to obtain the channel frequency domain response after combining the signals of satellite 1 and satellite 2;

[0010] S5: The terminal uses the minimum mean square error equalization algorithm to equalize the resource grid at the receiving end based on the synthesized channel frequency domain response, and obtains the recovered constellation points.

[0011] Furthermore, the resource grids of Satellite 1 and Satellite 2 have the same number of OFDM symbols and subcarriers, the pilot format of Satellite 1 and Satellite 2 has pilots evenly distributed on each OFDM symbol, the positions where the pilots and data of Satellite 1 and Satellite 2 overlap are set to zero, and the number of pilots on each OFDM symbol of Satellite 1 and Satellite 2 is the same.

[0012] Further, S3 includes:

[0013] S3.1: For satellites 1 and 2, the first OFDM symbol... The signals received by the terminals on each subcarrier and their output signals are respectively denoted as follows: and :

[0014]

[0015]

[0016] in , It refers to the number of resource grid subcarriers for Satellite 1 and Satellite 2. and Satellite 1 and Satellite 2 are respectively in the 1st and 2nd phases. The original signal is transmitted by each subcarrier. and Satellite 1 and Satellite 2 are respectively in the 1st and 2nd phases. Channel frequency domain response of each subcarrier and These are the frequency domain noises of the satellite 1 and satellite 2 signals received by the terminal, respectively.

[0017] Using LS channel estimation on the pilots of Satellite 1 and Satellite 2 in the receiver resource grid, and considering the effect of noise, the estimated channel frequency response at the pilot is as follows:

[0018]

[0019]

[0020] in , The number of pilots on an OFDM symbol;

[0021] S3.2: Estimate the channel frequency domain response at the pilot frequencies of satellites 1 and 2. and conduct Point IFFT yields the channel time-domain impulse response sequence at the pilot. and The calculation formula is as follows:

[0022]

[0023]

[0024] S3.3: Time-domain impulse response sequences of the pilot channels for Satellite 1 and Satellite 2 and ,Will The sequence after the point is set to zero to obtain the channel time-domain impulse response sequence after noise filtering. and The calculation formula is as follows:

[0025]

[0026]

[0027] in, The number of cyclic prefix points for the OFDM symbol;

[0028] S3.4: Channel time-domain impulse response sequences after noise filtering for Satellite 1 and Satellite 2 and The channel frequency domain response sequence is obtained by performing a Fourier transform. and Then, a cubic spline interpolation algorithm is used to obtain the channel frequency domain response sequences on all frequency domain subcarriers of satellite 1 and satellite 2. and .

[0029] Furthermore, the channel frequency domain response after combining the signals from Satellite 1 and Satellite 2 in step S4 for

[0030]

[0031] in These are the weighting coefficients for the frequency domain response sequence of satellite channel 1. These are the weighting coefficients for the frequency domain response sequence of satellite channel 2; and These two weighting coefficients are complex numbers with moduli between 0 and 1.

[0032] Furthermore, the restored constellation points for

[0033]

[0034] This is a composite signal from satellite 1 and satellite 2. For the first The equalization coefficient of each subcarrier is calculated as follows:

[0035]

[0036] in This represents noise power.

[0037] The beneficial effects of this invention are as follows:

[0038] This invention discloses a channel estimation and equalization method applicable to dual-satellite cooperative power enhancement, which solves the problem of large channel estimation and equalization errors on the terminal side caused by the low signal-to-noise ratio of a single-satellite link in dual-satellite cooperative power enhancement transmission scenarios. Attached Figure Description

[0039] Figure 1 This is a flowchart of a channel estimation and equalization method for dual-satellite cooperative power enhancement according to the present invention. Detailed Implementation

[0040] To more clearly illustrate the present invention, the following description, in conjunction with embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0041] like Figure 1 As shown, this invention discloses a channel estimation and equalization method suitable for dual-satellite cooperative power enhancement, the method comprising:

[0042] S1: Satellite 1 and Satellite 2 place pilot signals in their respective resource grids, which are then converted into radio frequency signals through inverse Fourier transform, digital-to-analog conversion, and up-conversion, and transmitted to the terminal.

[0043] S2: The terminal receives the radio frequency signals superimposed on satellite 1 and satellite 2 at the terminal antenna, and obtains the receiver resource grid through down-conversion, sampling and Fourier transform process, and extracts the pilot signals of satellite 1 and satellite 2 on the receiver resource grid;

[0044] S3: The terminal uses the extracted pilot signals of satellite 1 and satellite 2 to estimate the frequency domain response of the two channels respectively through the least squares-discrete Fourier transform channel estimation algorithm;

[0045] S4: The terminal combines the two channel frequency domain responses estimated by LS-DFT to obtain the channel frequency domain response after combining the signals of satellite 1 and satellite 2;

[0046] S5: The terminal uses the minimum mean square error equalization algorithm to equalize the resource grid at the receiving end based on the synthesized channel frequency domain response, and obtains the recovered constellation points.

[0047] Furthermore, the resource grids of Satellite 1 and Satellite 2 have the same number of OFDM symbols and subcarriers, the pilot format of Satellite 1 and Satellite 2 has pilots evenly distributed on each OFDM symbol, the positions where the pilots and data of Satellite 1 and Satellite 2 overlap are set to zero, and the number of pilots on each OFDM symbol of Satellite 1 and Satellite 2 is the same.

[0048] Further, S3 includes:

[0049] S3.1: For satellites 1 and 2, the first OFDM symbol... The signals received by the terminals on each subcarrier and their output signals are respectively denoted as follows: and :

[0050]

[0051]

[0052] in , It refers to the number of resource grid subcarriers for Satellite 1 and Satellite 2. and Satellite 1 and Satellite 2 are respectively in the 1st and 2nd phases. The original signal is transmitted by each subcarrier. and Satellite 1 and Satellite 2 are respectively in the 1st and 2nd phases. Channel frequency domain response of each subcarrier and These are the frequency domain noises of the satellite 1 and satellite 2 signals received by the terminal, respectively.

[0053] Using LS channel estimation on the pilots of Satellite 1 and Satellite 2 in the receiver resource grid, and considering the effect of noise, the estimated channel frequency response at the pilot is as follows:

[0054]

[0055]

[0056] in , The number of pilots on an OFDM symbol;

[0057] S3.2: Estimate the channel frequency domain response at the pilot frequencies of satellites 1 and 2. and conduct Point IFFT yields the channel time-domain impulse response sequence at the pilot. and The calculation formula is as follows:

[0058]

[0059]

[0060] S3.3: Time-domain impulse response sequences of the pilot channels for Satellite 1 and Satellite 2 and ,Will The sequence after the point is set to zero to obtain the channel time-domain impulse response sequence after noise filtering. and The calculation formula is as follows:

[0061]

[0062]

[0063] in, The number of cyclic prefix points for the OFDM symbol;

[0064] S3.4: Channel time-domain impulse response sequences after noise filtering for Satellite 1 and Satellite 2 and The channel frequency domain response sequence is obtained by performing a Fourier transform. and Then, a cubic spline interpolation algorithm is used to obtain the channel frequency domain response sequences on all frequency domain subcarriers of satellite 1 and satellite 2. and .

[0065] Furthermore, the channel frequency domain response after combining the signals from Satellite 1 and Satellite 2 in step S4 for

[0066]

[0067] in These are the weighting coefficients for the frequency domain response sequence of satellite channel 1. These are the weighting coefficients for the frequency domain response sequence of satellite channel 2; and These two weighting coefficients are complex numbers with moduli between 0 and 1.

[0068] Furthermore, the restored constellation points for

[0069]

[0070] This is a composite signal from satellite 1 and satellite 2. For the first The equalization coefficient of each subcarrier is calculated as follows:

[0071]

[0072] in This represents noise power.

[0073] Specifically, in this embodiment, the subscript "p," represents the component of the corresponding OFDM symbol pilot for the corresponding parameter;

[0074] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A channel estimation and equalization method suitable for dual-satellite cooperative power enhancement, characterized in that, The method includes: S1: Satellite 1 and Satellite 2 place pilot signals in their respective resource grids, which are then converted into radio frequency signals through inverse Fourier transform, digital-to-analog conversion, and up-conversion, and transmitted to the terminal. S2: The terminal receives the radio frequency signals superimposed on satellite 1 and satellite 2 at the terminal antenna, and obtains the receiver resource grid through down-conversion, sampling and Fourier transform process, and extracts the pilot signals of satellite 1 and satellite 2 on the receiver resource grid; S3: The terminal uses the extracted pilot signals of satellite 1 and satellite 2 to estimate the frequency domain response of the two channels respectively through the least squares-discrete Fourier transform channel estimation algorithm; S4: The terminal combines the two channel frequency domain responses estimated by LS-DFT to obtain the channel frequency domain response after combining the signals of satellite 1 and satellite 2; S5: The terminal uses the minimum mean square error equalization algorithm to equalize the resource grid at the receiving end based on the synthesized channel frequency domain response, and obtains the recovered constellation points.

2. The channel estimation and equalization method for dual-satellite cooperative power enhancement according to claim 1, characterized in that, Satellite 1 and Satellite 2 have the same number of OFDM symbols and subcarriers in their resource grids. The pilot format of Satellite 1 and Satellite 2 is that the pilots on each OFDM symbol are equally spaced. The positions where the pilots and data overlap on Satellite 1 and Satellite 2 are set to zero. Satellite 1 and Satellite 2 have the same number of pilots on each OFDM symbol.

3. The channel estimation and equalization method for dual-satellite cooperative power enhancement according to claim 1, characterized in that, S3 includes: S3.1: For satellites 1 and 2, the first OFDM symbol... The signals received by the terminals on each subcarrier are denoted as follows: and : ； ； in , It refers to the number of resource grid subcarriers for Satellite 1 and Satellite 2. and Satellite 1 and Satellite 2 are respectively in the 1st and 2nd phases. The original signal is transmitted by each subcarrier. and Satellite 1 and Satellite 2 are respectively in the 1st and 2nd phases. Channel frequency domain response of each subcarrier and These are the frequency domain noises of the satellite 1 and satellite 2 signals received by the terminal, respectively. Using LS channel estimation on the pilots of Satellite 1 and Satellite 2 in the receiver resource grid, and considering the effect of noise, the estimated channel frequency response at the pilot is as follows: ； ； in , The number of pilots on an OFDM symbol; S3.2: Estimate the channel frequency domain response at the pilot frequencies of satellites 1 and 2. and conduct Point IFFT yields the channel time-domain impulse response sequence at the pilot. and The calculation formula is as follows: ； ； S3.3: Time-domain impulse response sequences of the pilot channels for Satellite 1 and Satellite 2 and ,Will The sequence after the point is set to zero to obtain the channel time-domain impulse response sequence after noise filtering. and The calculation formula is as follows: ； ； in, The number of cyclic prefix points for the OFDM symbol; S3.4: Channel time-domain impulse response sequences after noise filtering for Satellite 1 and Satellite 2 and The channel frequency domain response sequence is obtained by performing a Fourier transform. and Then, a cubic spline interpolation algorithm is used to obtain the channel frequency domain response sequences on all frequency domain subcarriers of satellite 1 and satellite 2. and .

4. The channel estimation and equalization method for dual-satellite cooperative power enhancement according to claim 3, characterized in that, The channel frequency domain response after combining the signals from satellite 1 and satellite 2 in step S4 for ； in These are the weighting coefficients for the frequency domain response sequence of satellite channel 1. These are the weighting coefficients for the frequency domain response sequence of satellite channel 2; and These two weighting coefficients are complex numbers with moduli between 0 and 1.

5. The channel estimation and equalization method for dual-satellite cooperative power enhancement according to claim 4, characterized in that, Restored constellation points for ； The signal is a composite signal received by the terminal from Satellite 1 and Satellite 2. For the first The equalization coefficient of each subcarrier is calculated as follows: ； in This represents noise power.

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