Feed link adaptive transmission method based on ground terminal decision

Abstract

The invention relates to the field of satellite communication, discloses a feed link self-adaptive transmission method based on ground terminal decision, and relates to a feed link self-adaptive modulation coding mode conversion and uplink sending power adjustment technology in a low earth orbit satellite communication process. According to the method, the ground feed terminal is used as a statistics, storage and decision-making center of the channel state, the uplink and downlink modulation coding mode and the uplink sending power are made for adjustment decision according to the comparison of the signal-to-noise ratio of the uplink and downlink and the receiving power of the satellite-borne feed terminal with the set threshold value, the implementation difficulty of the satellite-borne feed terminal is reduced, and the implementation efficiency is improved. Therefore, the change of the channel state in the movement process of the low-orbit satellite is adapted, and the maximization and optimization of the channel capacity utilization are realized. The method is suitable for the transmission design of the low-orbit satellite feed link.

Description

Technical Field

[0001] The present invention relates to the field of satellite communications, and further to a feeder link adaptive transmission method based on ground terminal decision in the technical field of low-orbit satellite communications. Background Art

[0002] The feeder link is an important component of the low-orbit satellite communication system. It is mainly responsible for transmitting the user data received by the satellite to the ground, and transmitting the control instructions and data from the ground to the satellite. The transmission capacity of the link determines the size of the final user data transmission. During the movement of the low-orbit satellite, the channel state changes with the movement trajectory of the satellite. Obviously, choosing a consistent communication method cannot fully utilize the channel resources of the feeder link. Therefore, designing a feeder link adaptive transmission method has become the key to the design of the low-orbit satellite communication system. Summary of the invention

[0003] In order to avoid the problems in the background technology, the present invention proposes a feeder link adaptive transmission method based on ground terminal decision.

[0004] The technical solution adopted by the present invention is:

[0005] A feeder link adaptive transmission method based on ground terminal decision includes the following processes:

[0006] Uplink feeder link adaptive transmission method process:

[0007] Step 101, before the low-orbit satellite enters the station, the user selects the uplink control mode; when the uplink transmission power is independently controlled, the ground feed terminal initializes the uplink transmission power; when the uplink modulation and coding mode is independently controlled, the ground feed terminal initializes the uplink modulation and coding mode; when the uplink transmission power and the uplink modulation and coding mode are jointly controlled, the ground feed terminal initializes the uplink modulation and coding mode and the uplink transmission power; after initialization, the ground feed terminal sends an uplink feed link signal;

[0008] Step 102: After the low-orbit satellite enters the station, the onboard feed baseband platform adaptively demodulates the uplink feed link signal, estimates the uplink received power and the uplink signal-to-noise ratio; and composes the estimation results into a signaling frame, performs modulation and coding, and outputs a downlink feed link signal;

[0009] Step 103, the ground feed terminal receives the downlink feed link signal, and extracts the uplink received power and uplink signal-to-noise ratio estimation results after demodulation and decoding;

[0010] Step 104, the ground feed terminal generates an uplink control decision based on the uplink control mode selected by the user and the uplink received power and uplink signal-to-noise ratio estimation results, and sends an uplink feed link signal; then returns to step 102;

[0011] Downlink feeder link adaptive transmission method process:

[0012] Step 201, before the low-orbit satellite enters the station, the ground feed terminal initializes the downlink modulation and coding mode, and then sends an uplink feed link signal;

[0013] Step 202: After the low-orbit satellite enters the station, the onboard feed baseband platform receives the uplink feed link signal, extracts the downlink modulation and coding mode after adaptive demodulation and decoding, controls the modulation and coding mode of the downlink, and sends the downlink feed link signal;

[0014] Step 203, the ground feed terminal receives the downlink feed link signal, and estimates the downlink signal-to-noise ratio after demodulation;

[0015] Step 204: After obtaining the downlink signal-to-noise ratio estimation result, the ground feed terminal generates a control decision for the downlink modulation and coding mode, composes a signaling frame, and sends an uplink feed link signal; then returns to step 202.

[0016] Further, the uplink and downlink modulation and coding modes are ranked from low to high according to the demodulation threshold to form 0-N level modulation and coding modes, and each modulation and coding mode is set with an admission signal-to-noise ratio and an exit signal-to-noise ratio; wherein N is the type of the modulation and coding mode, and the admission signal-to-noise ratio and the exit signal-to-noise ratio are set according to the demodulation threshold; when step 101 and step 201 are initialized, the uplink modulation and coding mode and the downlink modulation and coding mode are both initialized to the 0th level modulation and coding mode.

[0017] Further, in step 104, when the uplink transmission power is independently controlled, the uplink control decision is:

[0018] 1) If the current uplink signal-to-noise ratio is less than the output signal-to-noise ratio SNR_OUT of the current uplink modulation and coding mode, proceed to step 2), otherwise proceed to step 4);

[0019] 2) If the current uplink received power is less than the saturation power of the satellite-borne feed baseband platform, proceed to step 3), otherwise proceed to step 6);

[0020] 3) Increase the uplink transmission power in a set step;

[0021] 4) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 6), otherwise proceed to step 5);

[0022] 5) Reduce the uplink transmission power in a set step;

[0023] 6) Keep the uplink transmit power unchanged.

[0024] Further, in step 104, when the uplink modulation and coding scheme is independently controlled, the uplink control decision is:

[0025] 1) If the current uplink signal-to-noise ratio is less than the current uplink modulation mode's standard output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 3);

[0026] 2) Adjust the uplink modulation and coding mode to a lower level modulation and coding mode;

[0027] 3) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 4), otherwise proceed to step 5);

[0028] 4) Keep the current uplink modulation and coding mode unchanged;

[0029] 5) Adjust the uplink modulation and coding mode to a higher level modulation and coding mode.

[0030] Further, in step 104, when the uplink transmission power and the uplink modulation and coding scheme are jointly controlled, the uplink control decision is:

[0031] 1) If the current uplink signal-to-noise ratio is less than the current uplink modulation mode's output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 5);

[0032] 2) If the current uplink received power is less than the saturation power of the satellite-borne feed baseband platform, proceed to step 3), otherwise proceed to step 4);

[0033] 3) Increase the uplink transmission power in a set step;

[0034] 4) Adjust the uplink modulation and coding mode to a lower level modulation and coding mode;

[0035] 5) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 6), otherwise proceed to step 7);

[0036] 6) Keep the current uplink transmit power and uplink modulation and coding mode unchanged;

[0037] 7) Adjust the uplink modulation and coding mode to a higher-level modulation and coding mode.

[0038] Furthermore, in step 204, the control decision of the downlink modulation and coding scheme is specifically:

[0039] 1) If the current downlink signal-to-noise ratio is less than the current downlink modulation mode's quasi-output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 3);

[0040] 2) Adjust the downlink modulation and coding mode to a lower level modulation and coding mode;

[0041] 3) If the current downlink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current downlink modulation and coding mode, proceed to step 4), otherwise proceed to step 5);

[0042] 4) Keep the current downlink modulation and coding mode unchanged;

[0043] 5) Adjust the downlink modulation and coding mode to a higher level modulation and coding mode.

[0044] The advantages of the present invention compared with the prior art are:

[0045] The present invention proposes to use the ground feeding terminal as the statistics, storage and decision center of the channel status, and make adjustments to the uplink and downlink modulation coding methods and the uplink transmission power based on the comparison of the signal-to-noise ratio of the uplink and downlink links and the receiving power of the satellite-borne feeding terminal with the set threshold, thereby reducing the difficulty of implementing the satellite-borne feeding baseband platform to adapt to the changes in the channel status during the movement of the low-orbit satellite, and realizing the maximization and optimization of the channel capacity utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a flow chart of independent control of uplink transmission power of a low-orbit satellite-to-ground feeder link according to an embodiment of the present invention.

[0047] Figure 2 This is a flow chart of independent control of uplink modulation and coding methods for a low-orbit satellite-to-ground feeder link according to an embodiment of the present invention.

[0048] Figure 3 This is a flow chart of the joint control of uplink transmission power and uplink modulation and coding mode of a low-orbit satellite-to-ground feeder link in an embodiment of the present invention.

[0049] Figure 4 This is a control flow chart of the downlink modulation and coding method of the low-orbit satellite-to-earth feeder link according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0051] The method of the present invention is implemented based on the low-orbit satellite feed link FDMA mode communication system, and the low-orbit satellite feed link communication system is composed of a satellite-borne feed baseband platform and a ground feed terminal. The satellite-borne feed baseband platform has an uplink feed link adaptive demodulation function, and extracts the uplink modulation and coding method through the feed link physical frame structure to perform uplink demodulation and decoding, without the need for additional configuration; it has an uplink received power and signal-to-noise ratio estimation function, and has a downlink modulation and coding method control instruction extraction function. In addition, the satellite-borne feed baseband platform also has a downlink feed link sending function, which can combine the uplink feed link received power estimation and signal-to-noise ratio results into a signaling frame, and modulate it into a downlink feed link signal using the extracted downlink modulation and coding method and send it out.

[0052] The ground feed terminal has a downlink feed link adaptive demodulation function, and extracts the downlink modulation and coding mode through the physical frame structure of the downlink feed link transmission to perform downlink feed link demodulation and decoding, without the need for additional configuration; it has a downlink signal-to-noise ratio estimation function; it has an uplink feed link receiving power and signal-to-noise ratio estimation result extraction function. It has an uplink feed link sending function, and can convert the downlink modulation and coding control instructions into an uplink signal through a signaling frame according to the uplink modulation and coding mode set by the user and send it out; it has a system adaptive transmission decision function, and as the decision center of the entire system, it is responsible for collecting the uplink and downlink feed link signal-to-noise ratio estimation results and the uplink receiving power estimation results, and generates adjustment decisions for the uplink sending power, the uplink modulation and coding mode, and the downlink modulation and coding mode according to the feed link adaptive transmission method in the present invention, and controls the adaptive transmission of the uplink and downlink feeder links.

[0053] The present invention discloses a feeder link adaptive transmission method based on ground terminal decision, which includes an uplink feeder link control method and a downlink feeder link control method. The uplink and downlink modulation and coding modes are ranked from low to high (0, 1, 2, ..., N) according to the demodulation threshold (the lowest demodulation signal-to-noise ratio with a bit error of 0), and each modulation and coding mode sets an admission signal-to-noise ratio (2dB higher than the demodulation threshold) and an exit signal-to-noise ratio (1dB higher than the demodulation threshold), forming a table stored in the ground feed terminal as a basis for the ground feed terminal to make a modulation and coding mode decision. When the satellite-borne feed baseband platform leaves the factory, it will provide the ground feed terminal with an optimal uplink transmission power and a saturation power of the satellite-borne feed baseband platform, which are stored in the ground feed terminal as a basis for the ground feed terminal to make an uplink transmission power decision.

[0054] The uplink feeder link adaptive transmission method process includes the following processes:

[0055] There are three uplink control modes selected by the user: independent control of uplink transmission power, independent control of uplink modulation and coding mode, and joint control of uplink transmission power and uplink modulation and coding mode.

[0056] like Figure 1 As shown, the uplink transmission power independent control includes the following steps:

[0057] Step 101: before the low-orbit satellite enters the station, the ground feed terminal initializes the uplink transmission power; after initialization, the ground feed terminal controls the uplink transmission power to send an uplink feed link signal;

[0058] Step 102: After the low-orbit satellite enters the station, the onboard feed baseband platform adaptively demodulates the uplink feed link signal, estimates the uplink received power and the uplink signal-to-noise ratio; and composes the estimation results into a signaling frame, performs modulation and coding, and outputs a downlink feed link signal;

[0059] Step 103, the ground feed terminal receives the downlink feed link signal, and extracts the uplink received power and uplink signal-to-noise ratio estimation results after demodulation and decoding;

[0060] Step 104: the ground feed terminal generates an uplink control decision based on the uplink control mode selected by the user, through the uplink received power and uplink signal-to-noise ratio estimation results, and sends an uplink feed link signal; then returns to step 102.

[0061] The uplink control decision of this embodiment is:

[0062] 1) If the current uplink signal-to-noise ratio is less than the output signal-to-noise ratio SNR_OUT of the current uplink modulation and coding mode, proceed to step 2), otherwise proceed to step 4);

[0063] 2) If the current uplink received power is less than the saturation power of the satellite-borne feed baseband platform, proceed to step 3), otherwise proceed to step 6);

[0064] 3) Increase the uplink transmission power by 0.5dB / s (adjustable step);

[0065] 4) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 6), otherwise proceed to step 5);

[0066] 5) Reduce the uplink transmission power by 0.5dB / s (adjustable step);

[0067] 6) Keep the uplink transmit power unchanged.

[0068] like Figure 2 As shown, the uplink modulation and coding mode includes the following steps when it is independently controlled:

[0069] Step 101: before the low-orbit satellite enters the station, the ground feed terminal initializes the uplink modulation and coding mode; after initialization, the ground feed terminal controls the uplink transmission power to send the uplink feed link signal;

[0070] Step 102: After the low-orbit satellite enters the station, the onboard feed baseband platform adaptively demodulates the uplink feed link signal, estimates the uplink received power and the uplink signal-to-noise ratio; and composes the estimation results into a signaling frame, performs modulation and coding, and outputs a downlink feed link signal;

[0071] Step 103, the ground feed terminal receives the downlink feed link signal, and extracts the uplink received power and uplink signal-to-noise ratio estimation results after demodulation and decoding;

[0072] Step 104: the ground feed terminal generates an uplink control decision based on the uplink control mode selected by the user, through the uplink received power and uplink signal-to-noise ratio estimation results, and sends an uplink feed link signal; then returns to step 102.

[0073] The uplink control decision of this embodiment is:

[0074] 1) If the current uplink signal-to-noise ratio is less than the current uplink modulation mode's standard output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 3);

[0075] 2) Adjust the uplink modulation and coding mode to a lower level modulation and coding mode;

[0076] 3) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 4), otherwise proceed to step 5);

[0077] 4) Keep the current uplink modulation and coding mode unchanged;

[0078] 5) Adjust the uplink modulation and coding mode to a higher level modulation and coding mode.

[0079] like Figure 3 As shown, the joint control of uplink transmission power and uplink modulation and coding mode includes the following steps:

[0080] Step 101: before the low-orbit satellite enters the station, the ground feed terminal initializes the uplink modulation and coding mode and the uplink transmission power; after initialization, the ground feed terminal controls the uplink transmission power to send an uplink feed link signal;

[0081] Step 102: After the low-orbit satellite enters the station, the onboard feed baseband platform adaptively demodulates the uplink feed link signal, estimates the uplink received power and the uplink signal-to-noise ratio; and composes the estimation results into a signaling frame, performs modulation and coding, and outputs a downlink feed link signal;

[0082] Step 103, the ground feed terminal receives the downlink feed link signal, and extracts the uplink received power and uplink signal-to-noise ratio estimation results after demodulation and decoding;

[0083] Step 104: the ground feed terminal generates an uplink control decision based on the uplink control mode selected by the user, through the uplink received power and uplink signal-to-noise ratio estimation results, and sends an uplink feed link signal; then returns to step 102.

[0084] The uplink control decision of this embodiment is:

[0085] 1) If the current uplink signal-to-noise ratio is less than the current uplink modulation mode's output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 5);

[0086] 2) If the current uplink received power is less than the saturation power of the satellite-borne feed baseband platform, proceed to step 3), otherwise proceed to step 4);

[0087] 3) Increase the uplink transmission power by 0.5dB / s (adjustable step);

[0088] 4) Adjust the uplink modulation and coding mode to a lower level modulation and coding mode;

[0089] 5) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 6), otherwise proceed to step 7);

[0090] 6) Keep the current uplink transmit power and uplink modulation and coding mode unchanged;

[0091] 7) Adjust the uplink modulation and coding mode to a higher-level modulation and coding mode.

[0092] like Figure 4 As shown, the downlink feeder link adaptive transmission method process includes the following processes:

[0093] Step 201, before the low-orbit satellite enters the station, the ground feed terminal initializes the downlink modulation and coding mode, and then sends an uplink feed link signal;

[0094] Step 202: After the low-orbit satellite enters the station, the onboard feed baseband platform receives the uplink feed link signal, extracts the downlink modulation and coding mode after adaptive demodulation and decoding, controls the modulation and coding mode of the downlink, and sends the downlink feed link signal;

[0095] Step 203, the ground feed terminal receives the downlink feed link signal, and estimates the downlink signal-to-noise ratio after demodulation;

[0096] Step 204: After obtaining the downlink signal-to-noise ratio estimation result, the ground feed terminal generates a control decision for the downlink modulation and coding mode, composes a signaling frame, and sends an uplink feed link signal; then returns to step 202.

[0097] The control decision of the downlink modulation and coding scheme is as follows:

[0098] 1) If the current downlink signal-to-noise ratio is less than the current downlink modulation mode's quasi-output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 3);

[0099] 2) Adjust the downlink modulation and coding mode to a lower level modulation and coding mode;

[0100] 3) If the current downlink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current downlink modulation and coding mode, proceed to step 4), otherwise proceed to step 5);

[0101] 4) Keep the current downlink modulation and coding mode unchanged;

[0102] 5) Adjust the downlink modulation and coding mode to a higher level modulation and coding mode.

Claims

1. A feeder link adaptive transmission method based on ground terminal decision, characterized in that: The process includes: Uplink feeder link adaptive transmission method process: Step 101, before the low-orbit satellite enters the station, the user selects the uplink control mode; when the uplink transmission power is independently controlled, the ground feed terminal initializes the uplink transmission power; When the uplink modulation and coding mode is independently controlled, the ground feed terminal initializes the uplink modulation and coding mode; when the uplink transmission power and the uplink modulation and coding mode are jointly controlled, the ground feed terminal initializes the uplink modulation and coding mode and the uplink transmission power; after initialization, the ground feed terminal sends an uplink feed link signal; Step 102: After the low-orbit satellite enters the station, the onboard feed baseband platform adaptively demodulates the uplink feed link signal to estimate the uplink received power and uplink signal-to-noise ratio; The estimation results are combined into a signaling frame, modulated and encoded, and a downlink feeder link signal is output; Step 103, the ground feed terminal receives the downlink feed link signal, and extracts the uplink received power and uplink signal-to-noise ratio estimation results after demodulation and decoding; Step 104, the ground feed terminal generates an uplink control decision based on the uplink control mode selected by the user and the uplink received power and uplink signal-to-noise ratio estimation results, and sends an uplink feed link signal; Then return to step 102; Downlink feeder link adaptive transmission method process: Step 201, before the low-orbit satellite enters the station, the ground feed terminal initializes the downlink modulation and coding mode, and then sends an uplink feed link signal; Step 202: After the low-orbit satellite enters the station, the onboard feed baseband platform receives the uplink feed link signal, extracts the downlink modulation and coding mode after adaptive demodulation and decoding, controls the modulation and coding mode of the downlink, and sends the downlink feed link signal; Step 203, the ground feed terminal receives the downlink feed link signal, and estimates the downlink signal-to-noise ratio after demodulation; Step 204: After obtaining the downlink signal-to-noise ratio estimation result, the ground feed terminal generates a control decision for the downlink modulation and coding mode, forms a signaling frame, and sends an uplink feed link signal; then returns to step 202.

2. A feeder link adaptive transmission method based on ground terminal decision according to claim 1, characterized in that: The uplink and downlink modulation and coding modes are ranked from low to high according to the demodulation threshold to form 0-N level modulation and coding modes, and each modulation and coding mode is set with an admission signal-to-noise ratio and an exit signal-to-noise ratio; wherein N is the type of the modulation and coding mode, and the admission signal-to-noise ratio and the exit signal-to-noise ratio are set according to the demodulation threshold; when step 101 and step 201 are initialized, the uplink modulation and coding mode and the downlink modulation and coding mode are both initialized to the 0th level modulation and coding mode.

3. A feeder link adaptive transmission method based on ground terminal decision according to claim 2, characterized in that: In step 104, when the uplink transmit power is independently controlled, the uplink control decision is: 1) If the current uplink signal-to-noise ratio is less than the output signal-to-noise ratio SNR_OUT of the current uplink modulation and coding mode, proceed to step 2), otherwise proceed to step 4); 2) If the current uplink received power is less than the saturation power of the satellite-borne feed baseband platform, proceed to step 3), otherwise proceed to step 6); 3) Increase the uplink transmission power in a set step; 4) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 6), otherwise proceed to step 5); 5) Reduce the uplink transmission power in a set step; 6) Keep the uplink transmit power unchanged.

4. The feeder link adaptive transmission method based on ground terminal decision according to claim 2, characterized in that: In step 104, when the uplink modulation and coding scheme is independently controlled, the uplink control decision is: 1) If the current uplink signal-to-noise ratio is less than the current uplink modulation mode's standard output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 3); 2) Adjust the uplink modulation and coding mode to a lower level modulation and coding mode; 3) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 4), otherwise proceed to step 5); 4) Keep the current uplink modulation and coding mode unchanged; 5) Adjust the uplink modulation and coding mode to a higher level modulation and coding mode.

5. The feeder link adaptive transmission method based on ground terminal decision according to claim 2, characterized in that: In step 104, when the uplink transmission power and the uplink modulation and coding scheme are jointly controlled, the uplink control decision is: 1) If the current uplink signal-to-noise ratio is less than the current uplink modulation mode's output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 5); 2) If the current uplink received power is less than the saturation power of the satellite-borne feed baseband platform, proceed to step 3), otherwise proceed to step 4); 3) Increase the uplink transmission power in a set step; 4) Adjust the uplink modulation and coding mode to a lower level modulation and coding mode; 5) If the current uplink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current uplink modulation and coding mode, proceed to step 6), otherwise proceed to step 7); 6) Keep the current uplink transmit power and uplink modulation and coding mode unchanged; 7) Adjust the uplink modulation and coding mode to a higher-level modulation and coding mode.

6. The feeder link adaptive transmission method based on ground terminal decision according to claim 2, characterized in that: In step 204, the control decision of the downlink modulation and coding scheme is specifically: 1) If the current downlink signal-to-noise ratio is less than the current downlink modulation mode's quasi-output signal-to-noise ratio SNR_OUT, proceed to step 2), otherwise proceed to step 3); 2) Adjust the downlink modulation and coding mode to a lower level modulation and coding mode; 3) If the current downlink signal-to-noise ratio is less than the admission signal-to-noise ratio SNR_IN of the current downlink modulation and coding mode, proceed to step 4), otherwise proceed to step 5); 4) Keep the current downlink modulation and coding mode unchanged; 5) Adjust the downlink modulation and coding mode to a higher level modulation and coding mode.

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