Satellite communication space information transmission method and system based on polarization switching and precoding

Abstract

The invention discloses a satellite communication space information transmission method based on polarization switching and precoding, which comprises the following steps of: preprocessing a signal at a transmitting end, dividing the duration of a symbol to be transmitted into a plurality of sub-time periods, and configuring different precoders for each period, therefore, extra space information is carried; in the transmission process, a satellite communication system dynamically switches the polarization direction of a receiving antenna, and processes a signal in combination with a corresponding precoder so as to improve the transmission performance, and codes spatial information bits by using the switching combination of the polarization direction of the receiving antenna, and in the signal transmission stage, the signal transmission efficiency is improved. The system transmits signal blocks carrying different receiving antenna and polarization direction information in different sub-time periods; and at a receiving end, the system adopts a maximum likelihood detection method to jointly estimate a modulation symbol, an activated receiving antenna and a polarization direction switching mode so as to recover complete transmission information. And the overall performance of the satellite communication system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of satellite communication, and in particular relates to a satellite communication space information transmission method and system based on polarization switching and precoding. Background Art

[0002] In the prior art, satellite communication systems have been widely used in the field of mobile communications to provide wide-area coverage and high-speed data transmission capabilities. Especially in land mobile satellite downlink communication systems, the selection of receiving antennas and the configuration of polarization directions have an important impact on the reception quality and transmission efficiency of signals. Traditional satellite communication systems usually use fixed antenna configurations and polarization directions, which cannot be flexibly adjusted according to transmission requirements. Therefore, there are certain limitations in improving system capacity and spectrum efficiency.

[0003] At present, a common practice is to improve the performance of satellite communication systems by adopting multi-antenna technology and precoding technology. Multi-antenna technology can achieve spatial diversity and multiplexing by increasing the number of receiving antennas, thereby improving the reliability and transmission rate of the system. Precoding technology can pre-process the signal at the transmitting end to optimize the performance of the signal during transmission and reduce interference and bit error rate.

[0004] Although these technologies have improved the performance of satellite communication systems to a certain extent, they do not fully utilize spatial information (such as the selection of receiving antennas and the configuration of polarization directions) to increase transmission efficiency and capacity. Existing multi-antenna technologies and precoding technologies often only focus on signal processing and optimization, while ignoring the potential value of spatial information in the transmission process.

[0005] Specifically, existing satellite communication systems usually only focus on how to achieve optimal signal transmission under given antenna configurations and polarization directions, without considering how to carry more information through these configurations. This results in more spectrum resources or transmission time being required to transmit the same amount of data, thereby reducing the overall efficiency of the system.

[0006] In addition, existing satellite communication systems also face some challenges, such as multipath effects, channel fading and interference. These problems are particularly prominent in complex communication environments, further limiting the transmission performance and reliability of the system.

[0007] In summary, the existing technology has made some progress in improving the performance of satellite communication systems, but there are still many shortcomings. In particular, in terms of how to use spatial information to increase transmission efficiency and capacity, the existing technology still needs to be further developed and improved. Therefore, a new satellite communication transmission method is urgently needed to overcome the limitations of the existing technology and improve the overall performance and efficiency of the system. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a satellite communication space information transmission method and system based on polarization switching and precoding, which solves the problems of limited transmission efficiency and capacity existing in existing satellite communication systems in the prior art.

[0009] The present invention adopts the following technical solutions to solve the above technical problems:

[0010] Satellite communication space information transmission method based on polarization switching and precoding,

[0011] Preprocess the signal at the transmitting end, divide the duration of the symbol to be transmitted into multiple sub-time periods, and configure different precoders for each period, which correspond to the polarization direction of the receiving antenna;

[0012] During the transmission process, the satellite communication system dynamically switches the polarization direction of the receiving antenna and processes the signal in combination with the corresponding precoder. The spatial information bits are encoded using the switching combination of the receiving antenna polarization direction. These bits and the conventional modulation symbol bits together constitute the complete transmission information. Through the predefined mapping table, the system maps the spatial information bits to a specific receiving antenna and polarization direction switching combination. During the signal transmission stage, the system transmits signal blocks carrying different receiving antenna and polarization direction information in different sub-time periods to ensure that the receiving end can accurately detect and decode the signal.

[0013] At the receiving end, the system uses the maximum likelihood detection method to jointly estimate the modulation symbols and the activated receiving antennas and polarization direction switching mode to recover the complete transmission information.

[0014] The time lengths of the multiple sub-time periods are equal, and a complete signal block can be transmitted in each sub-period.

[0015] In each sub-time period, the system dynamically switches the polarization direction of the receiving antenna, introduces an additional spatial dimension for signal transmission in each sub-time period, and applies precoding to each sub-time period so that the transmitted signal is transmitted in a specific receiving polarization direction.

[0016] Each signal block contains a corresponding precoded signal, and the modulation symbols transmitted in the sub-time period are the same. Considering the influence of channel fading, the transmitted signal is normalized and then sent to the land mobile satellite channel for transmission.

[0017] At the receiving end, what is received is a composite signal containing modulation symbol information and spatial information encoded by switching the receiving antenna and polarization direction; the most likely transmission signal sequence including the modulation symbol and the receiving antenna polarization direction switching mode is estimated through maximum likelihood detection. When the switching mode is detected, the receiving end decodes the received spatial information bits from the switching mode according to the mode and a predefined mapping table; at the same time, combined with the estimation of the modulation symbol, the receiving end completely restores all the transmitted information including the modulation symbol bits and the spatial information bits.

[0018] A satellite communication system based on polarization switching and precoding includes a transmitter and a receiver; the transmitter and the receiver are respectively equipped with dual-polarized antennas, and the polarization directions are left-hand circular polarization and right-hand circular polarization, respectively. dual-polarized antennas, the receiver is equipped with dual-polarized antennas, and assuming .

[0019] The dual-polarized antenna is modulated by quadrature phase shift keying.

[0020] The transmitter is arranged on the satellite, and the transmission signal is sent to the receiver via the transmission antenna after being sequentially subjected to bit splitting, space and symbol mapping, transmission block generation, and baseband pre-encoder.

[0021] The receiver is arranged in the user terminal. After the receiving antenna receives the signal sent by the transmitter, it passes through the maximum likelihood detection module and then performs demapping according to a preset mapping table to obtain all the transmitted information.

[0022] In the mapping process, the spatial information bits are mapped to corresponding switching combinations of antenna receiving antennas and polarization directions according to a mapping table.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. By introducing the polarization direction switching and precoding technology of the receiving antenna, the present invention can make full use of spatial information to increase the efficiency and capacity of transmission, thereby improving the overall performance of the satellite communication system without increasing spectrum resources or transmission time.

[0025] 2. The present invention adopts a novel space-time coding scheme, combining spatial information bits with modulation symbol bits, and transmitting additional spatial information by switching the receiving antenna and polarization direction. This design not only increases the amount of information transmitted each time, but also improves the reliability and anti-interference ability of signal transmission. At the same time, precoding technology is applied to each sub-time period to optimize the transmission performance of the transmitted signal in a specific receiving polarization direction, thereby further improving the spatial resolution of the signal. At the receiving end, through maximum likelihood detection, the transmitted spatial information bits and modulation symbol bits can be accurately restored to achieve complete reception and decoding of the signal.

[0026] 3. In practical applications, the present invention can be widely used in various satellite communication systems, including land mobile satellite communication, maritime satellite communication, aviation satellite communication and other fields. By improving the data transmission rate and spectrum efficiency, the present invention can significantly reduce the communication cost and improve the overall performance of the communication system. At the same time, its strong anti-interference ability and reliability also provide a strong guarantee for the stability of communication quality.

[0027] 4. The present invention also has good flexibility and scalability. By adjusting the switching mode of the receiving antenna and the polarization direction and the design of the mapping table, the performance of the system can be further optimized to adapt to different communication needs and scenarios. This flexibility makes the present invention have broad application prospects and huge market potential in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention provides a system configuration of an N×M dual-polarization MIMO land mobile satellite downlink communication system.

[0029] Figure 2 The present invention is a transceiver block diagram of a satellite communication system and information transmission method based on polarization switching and precoding.

[0030] Figure 3 It is a schematic diagram of a bit error rate performance curve of a satellite communication system based on polarization switching and precoding in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The structure and working process of the present invention will be further described below in conjunction with the accompanying drawings.

[0032] The purpose of the present invention is to provide a satellite communication space information transmission method based on polarization switching and precoding, aiming to overcome the problems of limited transmission efficiency and capacity in existing satellite communication systems. By introducing the polarization direction switching and precoding technology of the receiving antenna, the present invention can make full use of spatial information to increase the transmission efficiency and capacity, thereby improving the overall performance of the satellite communication system without increasing spectrum resources or transmission time.

[0033] A satellite communication spatial information transmission method based on polarization switching and precoding preprocesses the signal at the transmitting end, divides the duration of the symbol to be transmitted into multiple sub-time periods, and configures different precoders for each period. These precoders correspond to the polarization direction of the receiving antenna, thereby carrying additional spatial information.

[0034] During the transmission process, the satellite communication system dynamically switches the polarization direction of the receiving antenna and processes the signal in combination with the corresponding precoder to improve the transmission performance. The spatial information bits are encoded using the switching combination of the receiving antenna polarization direction. These bits and the conventional modulation symbol bits together constitute the complete transmission information. Through the predefined mapping table, the system maps the spatial information bits to a specific receiving antenna and polarization direction switching combination. In the signal transmission stage, the system transmits signal blocks carrying different receiving antenna and polarization direction information in different sub-time periods to ensure that the receiving end can accurately detect and decode the signal.

[0035] At the receiving end, the system uses the maximum likelihood detection method to jointly estimate the modulation symbols and the activated receiving antennas and polarization direction switching mode to recover the complete transmission information.

[0036] In addition, the method further considers the impact of channel fading on transmission performance, and improves the anti-interference ability and stability of the system by normalizing the transmitted signal and adjusting the precoder and polarization switching strategy.

[0037] First, the symbols to be transmitted are divided into multiple equal-length sub-time periods in time, which ensures that a complete signal block can be transmitted in each period, providing time separation and alignment for subsequent processing.

[0038] Next, according to the different polarization directions of different receiving antennas, a corresponding precoder is configured for each sub-time period to carry spatial information in the subsequent transmission process. According to the configuration of the precoder, the signal is subjected to necessary preprocessing such as modulation and encoding to ensure that the signal can smoothly carry and transmit spatial information in the subsequent transmission process.

[0039] In each sub-time period, the system dynamically switches the polarization direction of the receiving antenna, introducing an additional spatial dimension for signal transmission in each sub-time period. At the same time, precoding technology is applied to each sub-time period to optimize the transmission performance of the transmitted signal in a specific receiving polarization direction.

[0040] The spatial information bits are encoded by switching the polarization direction of the receiving antenna, and the spatial information bits together with the transmitted modulation symbol bits constitute the complete transmission information. Through the predefined mapping table, the system can accurately map the spatial information bits to the corresponding receiving antenna and polarization direction switching combination, realizing the seamless integration of spatial information and symbol information.

[0041] Signal blocks carrying different polarization direction information are transmitted in different sub-time periods, and each signal block contains the corresponding precoded signal. The modulation symbols transmitted in the sub-time period are the same, so that accurate signal detection and decoding can be performed at the receiving end. Considering the influence of channel fading (including large-scale fading and small-scale fading), the transmitted signal is normalized to ensure that the power of the transmitted signal is constant in each sub-time period. It is then sent to the land mobile satellite channel for transmission.

[0042] At the receiving end, a composite signal containing modulation symbol information and spatial information encoded by switching the receiving antenna and polarization direction is obtained. This method estimates the most likely transmitted signal sequence, including the switching pattern of modulation symbols and receiving antenna polarization direction, through maximum likelihood detection. Once the switching pattern is detected, the receiving end can decode the received spatial information bits from the switching pattern based on the pattern and a predefined mapping table. At the same time, combined with the estimation of the modulation symbols, the receiving end can completely recover all the transmitted information, including the modulation symbol bits and the spatial information bits.

[0043] Specific embodiments, such as Figures 1 to 3 As shown,

[0044] Consider a land mobile satellite downlink communication system such as Figure 1 The transmitter (satellite) and receiver (user terminal) are equipped with and dual-polarized antennas, with left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) respectively, and assuming In this scheme, each symbol duration is divided into two equal sub-time periods, namely and , changing the precoder in each sub-time period, using different polarization directions of different receiving antennas for reception. In this scheme, the switching of two receiving antennas and polarization directions carries spatial information. When the amplitude and / or phase modulation constellation is 2-dimensional, each transmission can transmit Bits. Part 1 It is the spatial information bit used to switch the receiving antenna and polarization direction. is a normal modulation symbol bit. Then, in the mapping process, the spatial information bit is mapped to the corresponding switching combination of the antenna receiving antenna and the polarization direction according to the mapping table, where The active receiving antenna and polarization direction are can be changed or remain unchanged. It should be noted that this method and The same modulation symbol is transmitted during the period. Table 1 shows An example of a time-space information bit map, and They are defined as and The index of the active receiving antenna; and They are defined as and direction of activity polarization.

[0045] Table 1 Mapping table of time-space information bits

[0046]

[0047] Then, according to the mapping table, we can get and Precoder selector during and , which is done by switching from Select a column from the . Then form a block ,in Transmitted in the first sub-time period, Transmitted in the second sub-time period. is a zero-forcing precoder that steers the transmitted signal to a specific subset of the received polarization directions. In order to normalize the power of the transmitted signal in each sub-time period, the normalization factor is:

[0048]

[0049] For example, a land mobile satellite downlink communication system using binary phase shift keying (BPSK) as the modulation constellation, where both the satellite and the user terminal are equipped with two dual-polarity antennas, such as Figure 2 As shown in FIG. 1 , the transmitted data bit is {01111}. According to Table 1, the spatial information bit {0111} indicates that the RHCP direction of the receiving antenna 1 is Activation, that is , =RHCP, the RHCP direction of the receiving antenna 2 is between and Activation, that is , =RHCP. In addition, the modulation symbol bit is {1}, that is, s = +1.

[0050] Channel It consists of two parts: large-scale fading component and small-scale fading component, which can be expressed as

[0051]

[0052] in, is the Rice factor, The elements of

[0053]

[0054] Among them, the phase and Uniformly distributed on [0,2π]. Obey Parameters The lognormal distribution of is the Rayleigh distribution with parameters It should be noted that different environments, different polarizations and different elevation angles Will affect The value of .

[0055] When transferring a block When the received signal can be expressed as

[0056]

[0057] in, is complex Gaussian noise, where each element is uncorrelated. Indicates that according to the switching mode of the mapping table, Selected in the sub-time period Columns.

[0058] At the receiving end, maximum likelihood detection is performed to jointly estimate the modulation symbols and the switching pattern of activated receive antennas and polarization directions by solving

[0059]

[0060] The switching mode is determined by The receiving end decodes the received spatial information from the switching pattern according to the pattern and the predefined mapping table. Combined with the estimation of the modulation symbols, the receiving end can completely recover all the transmitted information.

[0061] A satellite communication system based on polarization switching and precoding includes a transmitter and a receiver; the transmitter and the receiver are respectively equipped with dual-polarized antennas, and the polarization directions are left-hand circular polarization and right-hand circular polarization, respectively. dual-polarized antennas, the receiver is equipped with dual-polarized antennas, and assuming . Specific embodiments

[0063] In the embodiment of the present invention, K=10, the operating frequency is 2.2GHz, the satellite elevation angle is 40°, the cross-polarization discrimination of the antenna is 15dB, the cross-polarization coupling of the environment is 15dB, and the polarization correlation coefficients of the transmitting end and the receiving end are both 0.5. The receiving end is equipped with There are receiving antennas, all of which are dual-polarity antennas and use quadrature phase shift keying (QPSK) modulation. Analysis shows that the spectrum efficiency is 6bpcu.

[0064] The present invention is used in a land mobile satellite downlink communication system, and the simulation results are as follows: Figure 3 shown. Figure 3 The simulation results of the case where polarization switching is not used and the case where only single-polarity antenna is used are also provided. In the case where polarization switching is not used, 16 transmitting antennas are equipped at the transmitting end and 8 receiving antennas are equipped at the receiving end. All antennas are dual-polarity antennas and QPSK modulation is used, with a spectrum efficiency of 6bpcu. In the case where only single-polarity antenna is used, 16 transmitting antennas are equipped at the transmitting end and 8 receiving antennas are equipped at the receiving end. All antennas are monopolarity antennas and 8PSK modulation is used, with a spectrum efficiency of 5bpcu. When the bit error rate is When the polarization switching method is used, the present example obtains a gain of 3dB and 6dB respectively compared with the other two systems. Therefore, the present invention has a better bit error rate performance. The main reason for this performance improvement is that the antenna switching at the receiving end enhances the receiving diversity. In addition, the proposed polarization switching method requires fewer receiving antennas to obtain the same spectrum efficiency.

[0065] Those skilled in the art should understand that they can implement variations by combining the prior art and the above embodiments. Such variations do not affect the essence of the present solution and are not described in detail here.

[0066] It should be understood that the present solution is not limited to the above-mentioned specific implementation methods, and the devices and structures not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present solution without departing from the scope of the technical solution of the present solution, or modify it into an equivalent embodiment with equivalent changes, which does not affect the essential content of the present solution. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present solution without departing from the content of the technical solution of the present solution still falls within the scope of protection of the technical solution of the present solution.

Claims

1. A satellite communication space information transmission method based on polarization switching and precoding, characterized in that: Preprocess the signal at the transmitting end, divide the duration of the symbol to be transmitted into multiple sub-time periods, and configure different precoders for each period, which correspond to the polarization direction of the receiving antenna; During the transmission process, the satellite communication system dynamically switches the polarization direction of the receiving antenna and processes the signal in combination with the corresponding precoder. The spatial information bits are encoded using the switching combination of the receiving antenna polarization direction. These bits and the conventional modulation symbol bits together constitute the complete transmission information. Through the predefined mapping table, the system maps the spatial information bits to a specific receiving antenna and polarization direction switching combination. During the signal transmission stage, the system transmits signal blocks carrying different receiving antenna and polarization direction information in different sub-time periods to ensure that the receiving end can accurately detect and decode the signal. At the receiving end, the system uses the maximum likelihood detection method to jointly estimate the modulation symbols and the activated receiving antennas and polarization direction switching mode to recover the complete transmission information.

2. The satellite communication space information transmission method based on polarization switching and precoding according to claim 1 is characterized in that: The time lengths of the multiple sub-time periods are equal, and a complete signal block can be transmitted in each sub-period.

3. The satellite communication space information transmission method based on polarization switching and precoding according to claim 2 is characterized in that: In each sub-time period, the system dynamically switches the polarization direction of the receiving antenna, introduces an additional spatial dimension for signal transmission in each sub-time period, and applies precoding to each sub-time period so that the transmitted signal is transmitted in a specific receiving polarization direction.

4. The satellite communication space information transmission method based on polarization switching and precoding according to claim 1 is characterized in that: Each signal block contains a corresponding precoded signal, and the modulation symbols transmitted in the sub-time period are the same. Considering the influence of channel fading, the transmitted signal is normalized and then sent to the land mobile satellite channel for transmission.

5. The satellite communication space information transmission method based on polarization switching and precoding according to claim 4 is characterized in that: At the receiving end, what is received is a composite signal containing the modulation symbol information and the spatial information encoded by switching the receiving antenna and polarization direction; The most likely transmitted signal sequence including the modulation symbol and the receiving antenna polarization direction switching mode is estimated through maximum likelihood detection. When the switching mode is detected, the receiving end decodes the received spatial information bits from the switching mode according to the mode and a predefined mapping table. At the same time, combined with the estimation of the modulation symbol, the receiving end completely recovers all the transmitted information including the modulation symbol bits and the spatial information bits.

6. A satellite communication system based on polarization switching and precoding, characterized in that: The invention comprises a transmitter and a receiver; the transmitter and the receiver are respectively equipped with dual-polarized antennas, and the polarization directions are left-hand circular polarization and right-hand circular polarization, respectively. dual-polarized antennas, the receiver is equipped with dual-polarized antennas, and assuming .

7. The satellite communication system based on polarization switching and precoding according to claim 6, characterized in that: The dual-polarized antenna is modulated by quadrature phase shift keying.

8. The satellite communication system based on polarization switching and precoding according to claim 6, characterized in that: The transmitter is arranged on the satellite, and the transmission signal is sent to the receiver via the transmission antenna after being sequentially subjected to bit splitting, space and symbol mapping, transmission block generation, and baseband pre-encoder.

9. The satellite communication system based on polarization switching and precoding according to claim 8, characterized in that: The receiver is arranged in the user terminal. After the receiving antenna receives the signal sent by the transmitter, it passes through the maximum likelihood detection module and then performs demapping according to a preset mapping table to obtain all the transmitted information.

10. The satellite communication system based on polarization switching and precoding according to claim 9, characterized in that: In the mapping process, the spatial information bits are mapped to corresponding switching combinations of antenna receiving antennas and polarization directions according to a mapping table.

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