System for communication between satellite and ground equipment

Abstract

The invention provides a system for communication between a satellite and ground equipment, and the system comprises a geostationary orbit satellite which carries out the data transmission with first-type ground equipment through a time division multiple access system; the low earth orbit satellite uses a non-orthogonal multiple access system to carry out data transmission with the second type of ground equipment, and the communication between the low earth orbit satellite and the second type of ground equipment adopts a fixed transmission power or control transmission power strategy; the low earth orbit satellite is also equipped with a gateway supporting a continuous interference cancellation policy function for controlling a decoding order between different second type ground devices in the non-orthogonal multiple access system. According to the scheme, the communication of the non-orthogonal multiple access technology between the low earth orbit satellite and the ground equipment is realized, a plurality of users are allowed to communicate on the same time and frequency resource, and the spectrum utilization rate is remarkably improved.

Description

Technical Field

[0001] The present invention relates to satellite communication technology, and in particular to a communication system between a satellite and ground equipment. Background Art

[0002] With the rapid development of global informatization, wireless communication technology has become an important part of modern society. Especially in the field of satellite communications, geostationary orbit (GEO) satellites and low earth orbit (LEO) satellites are widely used in a variety of services such as television broadcasting, telephone, Internet access, and the Internet of Things (IoT) due to their unique advantages. However, with the surge in the number of connected devices, traditional communication methods face many challenges:

[0003] Tight spectrum resources: As the number of users and data demands grow, limited spectrum resources are becoming increasingly tight, leading to low spectrum utilization and communication congestion.

[0004] Signal coverage and quality: Although GEO satellites have a wide coverage area, they have high signal latency. Although LEO satellites have low latency, their coverage area is limited and they are greatly affected by the atmosphere, resulting in unstable signal coverage and quality.

[0005] Energy efficiency issues: Satellite communication equipment usually requires high energy consumption to maintain long-term operation, especially when using large antenna arrays and complex RF modules, energy efficiency becomes a key issue.

[0006] Limitations of multiple access technologies: Traditional multiple access technologies, such as time division multiple access (TDMA) and frequency division multiple access (FDMA), suffer from low efficiency and insufficient flexibility when handling a large number of user accesses.

[0007] Interference management: Interference between different signals is a significant issue in satellite communications, especially when multiple devices attempt to communicate on the same frequency and time resources. Interference management becomes even more important.

[0008] To solve the above problems, non-orthogonal multiple access (NOMA) technology was proposed as a new multiple access scheme, which allows multiple users to communicate on the same time and frequency resources and distinguishes the user's signals through different power levels. However, the application of NOMA technology in satellite communications still faces technical challenges such as channel prediction, power control and interference elimination.

[0009] Transmissive reconfigurable smart surface (T-RIS) technology, as an emerging technology, provides a way to improve signal coverage and reduce interference by adjusting the phase and amplitude of wireless signals. Although T-RIS shows great potential in terrestrial wireless communications, its application in communications between satellites and ground devices is still in the exploratory stage.

[0010] The present invention is proposed in the above background, and aims to optimize the communication system between satellites and ground equipment by combining NOMA technology and T-RIS technology, improve spectrum utilization, enhance signal coverage and quality, reduce energy consumption, and effectively manage interference to meet the growing demand for wireless communications. Summary of the invention

[0011] In view of this, the present invention provides a system for communication between a satellite and ground equipment, the system comprising:

[0012] A geostationary orbit satellite that uses a time division multiple access system to transmit data to a first type of ground equipment;

[0013] A low earth orbit satellite uses a non-orthogonal multiple access system to transmit data with a second type of ground equipment, wherein the communication between the low earth orbit satellite and the second type of ground equipment adopts a fixed transmission power or a controlled transmission power strategy; the low earth orbit satellite is also equipped with a gateway that supports a continuous interference elimination strategy function, which is used to control the decoding order between different second type ground equipment in the non-orthogonal multiple access system.

[0014] In particular, the first type of equipment includes: terrestrial equipment for providing television broadcasting, telephone or Internet access services; the second type of terrestrial equipment includes terrestrial equipment for providing Internet of Things applications.

[0015] In particular, the second type of ground equipment predicts channel fading characteristics from the low earth orbit satellite through probability distribution to achieve fixed transmission power or control transmission power strategy.

[0016] In particular, the low earth orbit (LEO) satellite predicts the channel fading characteristics through probability distribution to achieve a fixed transmission power or control transmission power strategy, and the prediction function form of the probability distribution is:

[0017] Where K is the Rice factor, which represents the power ratio between the line-of-sight (LOS) component and the non-line-of-sight (NLOS) component; is the log-normal shadow, describing the random variation of signal strength; h is the fading envelope of the wireless signal; I o is the zero-order modified Bessel function, which is used to describe the oscillatory behavior of the Rice distribution.

[0018] In particular, in the fixed transmission power strategy, the second type of ground equipment selects an appropriate time to transmit the signal so that the average power received by the satellite gateway meets the predetermined power level. The distance d from the second type of ground equipment to the satellite FTP It can be calculated by the following formula:

[0019]

[0020] in:

[0021] P represents a fixed transmission power,

[0022] G t and G r Represent the antenna gains of the transmitting and receiving ends respectively,

[0023] λ represents the wavelength of the signal,

[0024] L l represents a predefined receive power level;

[0025] In particular, in the control transmission power strategy, the second type of ground device transmits by adjusting the transmission power at any time within the visible time window of the satellite to achieve an average power level predefined by the gateway; the transmission power P required by the second type of ground device is CTP It can be calculated by the following formula:

[0026]

[0027] in:

[0028] d represents the distance from the second type of ground equipment to the satellite, L l Indicates a predefined receive power level.

[0029] In particular, the low earth orbit satellite is equipped with a transmissive reconfigurable smart surface unit for adjusting the phase and amplitude of the wireless signal to improve signal coverage and reduce interference; the phase offset matrix of the reconfigurable smart surface unit is expressed as:

[0030]

[0031] where η 1 ,η 2 ,...,η M ∈{0,1} represents the amplitude of the 1st, 2nd, ...Mth reconfigurable smart surface unit, represents the phase of the 1st, 2nd, ...Mth reconfigurable smart surface units, where M is the total number of reconfigurable smart surface units.

[0032] In particular, in the fixed transmission power strategy, the second type of ground equipment selects an appropriate time to transmit a signal so that the average power received by the satellite gateway meets a predetermined power level, and adjusts the phase and amplitude of the signal through the reconfigurable smart surface unit to optimize the signal transmission path;

[0033] In the control transmission power strategy, the second type of ground equipment transmits by adjusting the transmission power at any time within the visible time window of the satellite to achieve the average power level predefined by the gateway, and adjusts the phase and amplitude of the transmission signal through the reconfigurable smart surface unit to optimize the signal transmission path.

[0034] In particular, the system optimizes the total transmission power of the low earth orbit satellite, non-orthogonal multiple access (NOMA) power allocation and phase offset design of the reconfigurable smart surface unit to maximize the total rate of the low earth orbit satellite communication while ensuring the quality of service of the geostationary orbit satellite network users, wherein:

[0035] The superimposed signal x of the transmission signals of the low earth orbit satellite and the second type of ground equipment i and j is

[0036]

[0037] where p i and p j are the power allocation coefficients of the second type ground equipment i and j, P t is the total transmission power of the low earth orbit satellite; x i and x j are the unit power signals of the second type ground devices i and j, represents the signal transmitted from the second type of ground equipment i, and represents the signal transmitted from the second type of ground equipment j; here, p i and p j are the power coefficients allocated according to the NOMA strategy, which ensure the power difference of the signal at the receiving end; for devices i and j, the received power ratio of the signal can be defined as:

[0038]

[0039] in:

[0040] g i and g j are the channel gains from the second type ground equipment i and j to the LEO satellite,

[0041] Φ t is the phase offset matrix of the reconfigurable smart surface unit,

[0042] p i and p j are the power coefficients assigned to the second type ground equipment i and j, respectively,

[0043] P t is the total transmission power of the LEO satellite,

[0044] σ 2 is the noise power;

[0045] The subscript i≠j denotes the summation over all other second-type ground devices, except the second-type ground devices i and j themselves;

[0046] In the above formula, SIR i The ratio of the transmission signal power of the second type of ground equipment i to the total interference power it receives, SIR j Represents the ratio of the transmission signal power of the second type ground device j to the total interference power it receives.

[0047] In particular, the low-earth orbit satellite is equipped with a gateway that supports a continuous interference cancellation strategy function. In a non-orthogonal multiple access system, the continuous interference cancellation strategy includes: a second type of ground device with a higher signal receiving power ratio will be decoded first, and then its signal will be eliminated from the total received signal in order to decode the second type of ground device signal with a lower signal receiving power ratio.

[0048] Beneficial effects:

[0049] Through the technical solution of the present invention, non-orthogonal multiple access (NOMA) technology is implemented in communication between low earth orbit (LEO) satellites and ground equipment, allowing multiple users to communicate on the same time and frequency resources, significantly improving spectrum utilization.

[0050] Through the technical solution of the present invention, the phase and amplitude of the wireless signal are adjusted by utilizing the transmissive reconfigurable intelligent surface, the signal coverage is optimized and interference is reduced, thereby improving the signal reception quality and communication reliability.

[0051] Through the technical solution of the present invention, a fixed transmission power and a control transmission power strategy are implemented, so that the device can dynamically adjust the transmission power according to the channel conditions, thereby reducing energy consumption and improving the energy efficiency of the system.

[0052] Through the technical solution of the present invention, the interference from LEO satellite to geostationary orbit (GEO) satellite is controlled, the service quality of GEO network users is ensured, and at the same time the transmission strategy of the LEO satellite network is optimized to reduce mutual interference between networks.

[0053] Through the technical solution of the present invention, the overall transmission rate and reliability of the system are improved through precise power control and interference management, especially in an environment with dense users or complex channel conditions, the system capacity is significantly improved.

[0054] The technical solution of the present invention provides a flexible network deployment method, which can flexibly select and adjust FTP and CTP strategies according to specific application requirements and environmental conditions to adapt to different communication scenarios.

[0055] Through the technical solution of the present invention, the IoT device can dynamically adjust the transmission power according to the predicted channel fading characteristics and real-time channel state information, thereby optimizing the energy consumption of the device and extending the service life of the device.

[0056] Through the technical solution of the present invention, the system can more effectively resist the interference caused by multipath effect and channel fading, and improve the anti-interference ability of the system in complex environments.

[0057] Through the technical solution of the present invention, various application scenarios ranging from smart cities, remote monitoring to broadband Internet access are supported, providing customized communication services for different users.

[0058] The technical solution of the present invention simplifies the design and maintenance of the system, because the prediction of channel fading characteristics through probability distribution can reduce the dependence on complex channel estimation and feedback mechanisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 The invention provides a system for communication between satellites and ground equipment. DETAILED DESCRIPTION

[0060] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0061] The present invention provides a system for communication between a satellite and ground equipment, such as Figure 1 As shown, the system comprises:

[0062] A geostationary orbit satellite that uses a time division multiple access system to transmit data to a first type of ground equipment;

[0063] A low earth orbit satellite uses a non-orthogonal multiple access system to transmit data with a second type of ground equipment, wherein the communication between the low earth orbit satellite and the second type of ground equipment adopts a fixed transmission power or a controlled transmission power strategy; the low earth orbit satellite is also equipped with a gateway that supports a continuous interference elimination strategy function, which is used to control the decoding order between different second type ground equipment in the non-orthogonal multiple access system. It is necessary to achieve effective communication between geostationary orbit (GEO) satellites and low earth orbit (LEO) satellites and ground equipment. GEO satellites are responsible for providing a wide range of service coverage, such as television broadcasting, telephone and Internet access, while LEO satellites focus on providing Internet of Things (IoT) application services, such as smart cities and remote monitoring. That is, the first type of equipment includes: ground equipment for providing television broadcasting, telephone or Internet access services; the second type of ground equipment includes ground equipment for providing IoT applications.

[0064] The second type of ground device to the low earth orbit satellite predicts the channel fading characteristics through probability distribution to achieve a fixed transmission power or control the transmission power strategy. The communication strategy between the second type of ground device (i.e., the device used for IoT applications) and the low earth orbit (LEO) satellite is to achieve a fixed transmission power or control the transmission power by predicting the channel fading characteristics. Specifically, predicting the channel fading characteristics includes: data collection and analysis, collecting historical and real-time channel state information (CSI), including signal strength, signal quality, multipath effect, etc.

[0065] These data are analyzed to determine the statistical properties of the channel fading, such as mean, variance, distribution shape, etc.

[0066] Build a probability distribution model: Based on the collected data, build a probability distribution model to describe the channel fading characteristics. Usually, this can be achieved through Rice distribution, Rayleigh distribution, Log-normal distribution, etc.

[0067] For example, the Rice distribution is used to simulate a channel with direct (LOS) and multipath (NLOS) components.

[0068] Parameter estimation: Estimate the parameters of the probability distribution model, such as Rice factor (K), lognormal shadow (S), etc. These parameters reflect the specific characteristics of the channel, such as the relative strength of LOS and NLOS components.

[0069] Fixed transmit power strategy: A fixed transmit power level is assigned to each IoT device based on the predicted channel fading characteristics.

[0070] The device selects an appropriate time to transmit the signal so that the average power received by the satellite gateway meets a predetermined power level.

[0071] Controlled Transmit Power (CTP) strategy: The device dynamically adjusts its transmit power based on the real-time channel status and predicted channel fading characteristics. This strategy allows the device to transmit at any time within the satellite's visible time window by adjusting the transmit power to achieve the gateway's predefined average power level.

[0072] The low earth orbit (LEO) satellite predicts the channel fading characteristics through probability distribution to achieve a fixed transmission power or control transmission power strategy, and the prediction function form of the probability distribution is:

[0073] Where K is the Rice factor, which represents the power ratio of the line-of-sight (LOS) component to the non-line-of-sight (NLOS) component; is the log-normal shadow, describing the random variation of signal strength; h is the fading envelope of the wireless signal; I o is the zero-order modified Bessel function, which is used to describe the oscillatory behavior of the Rice distribution.

[0074] In the fixed transmission power strategy, the device selects an appropriate time to transmit the signal so that the average power received by the satellite gateway meets the predetermined power level. The distance d from the device to the satellite FTP It can be calculated by the following formula:

[0075]

[0076] in:

[0077] P represents a fixed transmission power,

[0078] G t and G r Represent the antenna gains of the transmitting and receiving ends respectively,

[0079] λ represents the wavelength of the signal,

[0080] L l represents a predefined receive power level;

[0081] In particular, in the control transmission power strategy, the second type of ground device transmits by adjusting the transmission power at any time within the visible time window of the satellite to achieve an average power level predefined by the gateway; the transmission power P required by the second type of ground device is CTP It can be calculated by the following formula:

[0082]

[0083] in:

[0084] d represents the distance from the second type of ground equipment to the satellite, L lIndicates a predefined receive power level.

[0085] The low earth orbit satellite is equipped with a transmissive reconfigurable smart surface unit for adjusting the phase and amplitude of the wireless signal to improve signal coverage and reduce interference; the phase offset matrix of the reconfigurable smart surface unit is expressed as:

[0086]

[0087] where η 1 ,η 2 ,...,η M ∈{0,1} represents the amplitude of the 1st, 2nd, ...Mth reconfigurable smart surface unit, represents the phase of the 1st, 2nd, ...Mth reconfigurable smart surface units, where M is the total number of reconfigurable smart surface units.

[0088] In the fixed transmission power strategy, the second type of ground equipment selects an appropriate time to transmit a signal so that the average power received by the satellite gateway meets a predetermined power level, and adjusts the phase and amplitude of the signal through the reconfigurable smart surface unit to optimize the signal transmission path;

[0089] In the control transmission power strategy, the second type of ground equipment transmits by adjusting the transmission power at any time within the visible time window of the satellite to achieve an average power level predefined by the gateway, and the phase and amplitude of the adjustment signal of the smart surface unit can be reconfigured to optimize the signal transmission path.

[0090] The system optimizes the total transmission power of the low earth orbit satellite, the non-orthogonal multiple access (NOMA) power allocation and the phase offset design of the reconfigurable smart surface unit to maximize the total rate of the low earth orbit satellite communication while ensuring the service quality of the geostationary orbit satellite network users, wherein:

[0091] The superimposed signal x of the transmission signals of the low earth orbit satellite and the second type ground devices i and j is

[0092]

[0093] where p i and p j are the power allocation coefficients of the second type ground equipment i and j, P t is the total transmission power of the low earth orbit satellite; x i and x j are the unit power signals of the second type ground devices i and j respectively, represents the signal transmitted from the second type of ground equipment i, and represents the signal transmitted from the second type of ground equipment j; here, p i and p j are the power coefficients allocated according to the NOMA strategy, which ensure the power difference of the signal at the receiving end; for devices i and j, the received power ratio of the signal can be defined as:

[0094]

[0095] in:

[0096] g i and g j are the channel gains from the second type ground equipment i and j to the LEO satellite,

[0097] Φ t is the phase offset matrix of the reconfigurable smart surface unit,

[0098] p i and p j are the power coefficients assigned to the second type ground equipment i and j, respectively,

[0099] P t is the total transmission power of the LEO satellite,

[0100] σ 2 is the noise power;

[0101] The subscript i≠j denotes the summation over all other second-type ground devices, except the second-type ground devices i and j themselves;

[0102] In the above formula, SIR i The ratio of the transmission signal power of the second type of ground equipment i to the total interference power it receives, SIR j Represents the ratio of the transmission signal power of the second type ground device j to the total interference power it receives.

[0103] The low-Earth orbit satellite is equipped with a gateway that supports a continuous interference cancellation strategy function. In a non-orthogonal multiple access system, the continuous interference cancellation strategy includes: a second type of ground device with a higher signal receiving power ratio will be decoded first, and then its signal will be eliminated from the total received signal in order to decode the second type of ground device signal with a lower signal receiving power ratio.

[0104] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0105] It is obvious to those skilled in the art that the embodiments of the present invention are not limited to the details of the above exemplary embodiments, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or basic features of the embodiments of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the embodiments of the present invention is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the embodiments of the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules or devices stated in the system, device or terminal claims can also be implemented by the same unit, module or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

[0106] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred implementation modes, those skilled in the art should understand that the technical solutions of the embodiments of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for communication between a satellite and ground equipment, characterized in that: The system comprises: A geostationary orbit satellite that uses a time division multiple access system to transmit data to a first type of ground equipment; A low earth orbit satellite uses a non-orthogonal multiple access system to transmit data with a second type of ground equipment, wherein the communication between the low earth orbit satellite and the second type of ground equipment adopts a fixed transmission power or a controlled transmission power strategy; the low earth orbit satellite is also equipped with a gateway that supports a continuous interference elimination strategy function, which is used to control the decoding order between different second type ground equipment in the non-orthogonal multiple access system.

2. The system according to claim 1, characterized in that The first type of equipment includes: ground equipment for providing television broadcasting, telephone or Internet access services; the second type of ground equipment includes ground equipment for providing Internet of Things applications.

3. The system according to claim 2, characterized in that The second type of ground equipment predicts channel fading characteristics from the low earth orbit satellite through probability distribution to achieve fixed transmission power or control transmission power strategy.

4. The system according to claim 3, characterized in that The low earth orbit (LEO) satellite predicts the channel fading characteristics through probability distribution to achieve a fixed transmission power or control transmission power strategy, and the prediction function form of the probability distribution is: Where K is the Rice factor, which represents the power ratio between the line-of-sight (LOS) component and the non-line-of-sight (NLOS) component; is the log-normal shadow, describing the random variation of signal strength; h is the fading envelope of the wireless signal; I o is the zero-order modified Bessel function, which is used to describe the oscillatory behavior of the Rice distribution.

5. The system according to claim 4, characterized in that In the fixed transmission power strategy, the second type of ground equipment selects an appropriate time to transmit the signal so that the average power received by the satellite gateway meets the predetermined power level. The distance d from the second type of ground equipment to the satellite FTP Calculated by the following formula: in: P represents a fixed transmission power, G t and G r Represent the antenna gains of the transmitting and receiving ends respectively, λ represents the wavelength of the transmitted signal, L l Indicates a predefined receive power level.

6. The system according to claim 5, characterized in that In the control transmission power strategy, the second type of ground equipment transmits by adjusting the transmission power at any time within the visible time window of the satellite to achieve the average power level predefined by the gateway; the transmission power P required by the second type of ground equipment CTP Calculated by the following formula: in: d represents the distance from the second type of ground equipment to the satellite, L l Indicates a predefined receive power level.

7. The system according to claim 6, characterized in that The low earth orbit satellite is equipped with a transmissive reconfigurable smart surface unit for adjusting the phase and amplitude of the wireless signal to improve signal coverage and reduce interference; the phase offset matrix of the reconfigurable smart surface unit is expressed as: where η1,η2,...,η M ∈{0,1} represents the amplitude of the 1st, 2nd, ...Mth reconfigurable smart surface unit, represents the phase of the 1st, 2nd, ...Mth reconfigurable smart surface units, where M is the total number of reconfigurable smart surface units.

8. The system according to claim 7, characterized in that In the fixed transmission power strategy, the second type of ground equipment selects an appropriate time to transmit a signal so that the average power received by the satellite gateway meets a predetermined power level, and adjusts the phase and amplitude of the signal through the reconfigurable smart surface unit to optimize the signal transmission path; In the control transmission power strategy, the second type of ground equipment transmits by adjusting the transmission power at any time within the visible time window of the satellite to achieve the average power level predefined by the gateway, and adjusts the phase and amplitude of the transmission signal through the reconfigurable smart surface unit to optimize the signal transmission path.

9. The system according to claim 8, characterized in that The system optimizes the total transmission power of the low earth orbit satellite, the non-orthogonal multiple access (NOMA) power allocation and the phase offset design of the reconfigurable smart surface unit to maximize the total rate of the low earth orbit satellite communication while ensuring the service quality of the geostationary orbit satellite network users, wherein: The superimposed signal x of the transmission signals of the low earth orbit satellite and the second type of ground equipment i and j is where p i and p j are the power allocation coefficients of the second type ground equipment i and j, respectively, P t is the total transmission power of the low earth orbit satellite; x i and x j are the unit power signals of the second type ground devices i and j respectively, represents the signal transmitted from the second type of ground equipment i, and represents the signal transmitted from the second type of ground equipment j; here, p i and p j are the power coefficients allocated according to the NOMA strategy, which ensure the power difference of the signal at the receiving end; for devices i and j, the received power ratio of the signal can be defined as: in: g i and g j are the channel gains from the second type ground equipment i and j to the LEO satellite, Φ t is the phase offset matrix of the reconfigurable smart surface unit, p i and p j are the power coefficients assigned to the second type ground equipment i and j, respectively, P t is the total transmission power of the LEO satellite, σ 2 is the noise power; The subscript i≠j denotes the summation over all other second-type ground devices, except the second-type ground devices i and j themselves; In the above formula, SIR i The ratio of the transmission signal power of the second type of ground equipment i to the total interference power it receives, SIR j Represents the ratio of the transmission signal power of the second type ground device j to the total interference power it receives.

10. The system according to claim 9, characterized in that The low-earth orbit satellite is equipped with a gateway that supports a continuous interference cancellation strategy function. In a non-orthogonal multiple access system, the continuous interference cancellation strategy includes: a second type of ground device with a higher signal receiving power ratio will be decoded first, and then its signal will be eliminated from the total received signal in order to decode the second type of ground device signal with a lower signal receiving power ratio.

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