阅读说明：本技术 下行链路发送方法、装置、电子设备及计算机可读介质 (Downlink transmission method, apparatus, electronic device, and computer-readable medium ) 是由 王柳一 高超 董玮 于 2021-12-07 设计创作，主要内容包括：本公开涉及一种用于卫星通信的下行链路发送方法、装置、电子设备及计算机可读介质。该方法包括：构建卫星通信的波束边缘用户组,所述波束边缘用户组包括多个用户；将所述波束边缘用户组中的多个用户分为多个编码用户组；为所述多个编码用户组中的每个编码用户组中的用户分配相同频点；基于每个编码用户组中用户的相同频点为用户生成多个预编码；基于所述多个预编码进行下行链路发送。本公开涉及的用于卫星通信的下行链路发送方法、装置、电子设备及计算机可读介质,能够将卫星通信移动信道正交化,起到抑制干扰合并的作用,获取较好的信道容量性能。(The present disclosure relates to a downlink transmission method, apparatus, electronic device, and computer-readable medium for satellite communication. The method comprises the following steps: constructing a beam edge user group of satellite communication, wherein the beam edge user group comprises a plurality of users; dividing a plurality of users in the beam edge user group into a plurality of coding user groups; distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; performing downlink transmission based on the plurality of precodes. The downlink transmission method, the downlink transmission device, the electronic equipment and the computer readable medium for satellite communication can orthogonalize a satellite communication mobile channel, play a role in restraining interference combination and acquire better channel capacity performance.)

1. A downlink transmission method for satellite communication, comprising:

constructing a beam edge user group of satellite communication, wherein the beam edge user group comprises a plurality of users;

dividing a plurality of users in the beam edge user group into a plurality of coding user groups;

distributing the same frequency points for the users in each coding user group in the plurality of coding user groups;

generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group;

performing downlink transmission based on the plurality of precodes.

2. The method of claim 1, wherein constructing a set of beam edge users for satellite communications comprises:

and constructing a beam edge user group based on the distance of the user from the beam center.

3. The method of claim 1, wherein dividing the plurality of users in the beam-edge user group into a plurality of encoded user groups comprises:

extracting a first user and a second user from a plurality of users in the beam edge user group;

generating a coded user group by the first user and the second user;

and when all the users in the beam edge user group are extracted, generating the plurality of coding user groups.

4. The method of claim 3, wherein extracting the first and second ones of the plurality of users in the beam-edge user group comprises:

sequentially extracting the farthest user in the beam edge user group as a first user;

and sequentially extracting the farthest user of the adjacent subareas of the adjacent wave beams in the wave beam edge user group as a second user.

5. The method of claim 1, wherein allocating the same frequency bins for users in each of the plurality of coded user groups comprises:

and allocating the same frequency points to the first user and the second user in each coding user group in the plurality of coding user groups.

6. The method of claim 1, wherein generating a plurality of precodes for users based on the same frequency points of the users in each coded user group comprises:

respectively constructing equivalent channel matrixes for the user groups based on the same frequency points of the users in each user group;

a plurality of precodes is generated based on the plurality of equivalent channel matrices.

7. The method of claim 6, wherein generating a plurality of precodes based on a plurality of equivalent channel matrices comprises:

initializing a sending end precoding matrix based on the equivalent channel matrix;

solving the precoding matrix of the sending end;

and generating the precoding when the solution of the precoding matrix of the sending end meets the condition.

8. The method of claim 7, wherein prior to solving the transmit-end precoding matrix, further comprising:

and solving the Lagrangian multiplier.

9. The method of claim 1, wherein the downlink transmission based on the plurality of precodes comprises:

and transmitting the plurality of precodes to a receiving end through a downlink channel of the satellite.

10. A downlink transmission apparatus for satellite communication, comprising:

the satellite communication system comprises a construction module, a communication module and a communication module, wherein the construction module is used for constructing a beam edge user group of satellite communication, and the beam edge user group comprises a plurality of users;

a user group module, configured to divide a plurality of users in the beam edge user group into a plurality of coding user groups;

the distribution module is used for distributing the same frequency points for the users in each coding user group in the plurality of coding user groups;

the pre-coding module is used for generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group;

a transmitting module configured to perform downlink transmission based on the plurality of precodes.

11. An electronic device, comprising:

one or more processors;

storage means for storing one or more programs;

when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-9.

12. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to any one of claims 1-9.

Technical Field

The present disclosure relates to the field of computer information processing, and in particular, to a downlink transmission method and apparatus for satellite communication, an electronic device, and a computer-readable medium.

Background

In traditional algorithm research, accurate and reliable mechanism estimation is always the key to solve mass data transmission. The conventional Channel State Information (CSI) is obtained by comparing training data sequences of a transmitting end and a receiving end, and is generally two-dimensional when processing the fluctuation of a channel transfer function in time and frequency domains. Thus, neither the training sequence nor the more common pilot symbols can carry any payload data resources resulting from a topological session of a certain time and frequency.

Obviously, on a mesh network with more pilot symbols and denser time-frequency, the CSI value is more reliable, the complexity of the model and calculation correspondingly increases the requirement for real-time signal transmission, but the effect is still not ideal, and the high cost of network calculation is not suitable for the network throughput.

Accordingly, there is a need for a new downlink transmission method, apparatus, electronic device, and computer readable medium for satellite communication.

The above information disclosed in this background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

In view of the above, the present disclosure provides a downlink transmission method, an apparatus, an electronic device and a computer readable medium for satellite communication, which can orthogonalize a satellite communication mobile channel, perform an interference combining suppression function, and obtain a better channel capacity performance.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows, or in part will be obvious from the description, or may be learned by practice of the disclosure.

According to an aspect of the present disclosure, a downlink transmission method for satellite communication is provided, the method including: constructing a beam edge user group of satellite communication, wherein the beam edge user group comprises a plurality of users; dividing a plurality of users in the beam edge user group into a plurality of coding user groups; distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; performing downlink transmission based on the plurality of precodes.

In an exemplary embodiment of the present disclosure, constructing a beam edge user group for satellite communication includes: and constructing a beam edge user group based on the distance of the user from the beam center.

In an exemplary embodiment of the present disclosure, dividing the plurality of users in the beam-edge user group into a plurality of encoded user groups includes: extracting a first user and a second user from a plurality of users in the beam edge user group; generating a coded user group by the first user and the second user; and when all the users in the beam edge user group are extracted, generating the plurality of coding user groups.

In an exemplary embodiment of the present disclosure, extracting a first user and a second user of a plurality of users in the beam-edge user group includes: sequentially extracting the farthest user in the beam edge user group as a first user; and sequentially extracting the farthest user of the adjacent subareas of the adjacent wave beams in the wave beam edge user group as a second user.

In an exemplary embodiment of the present disclosure, allocating the same frequency point to users in each of the plurality of encoded user groups includes: and allocating the same frequency points to the first user and the second user in each coding user group in the plurality of coding user groups.

In an exemplary embodiment of the present disclosure, generating multiple precodes for users based on the same frequency point of the users in each coding user group includes: respectively constructing equivalent channel matrixes for the user groups based on the same frequency points of the users in each user group; generating a plurality of precodes based on a plurality of equivalent channel matrices;

in an exemplary embodiment of the present disclosure, generating a plurality of precodes based on a plurality of equivalent channel matrices includes: initializing a sending end precoding matrix based on the equivalent channel matrix; solving the precoding matrix of the sending end; and generating the precoding when the solution of the precoding matrix of the sending end meets the condition.

In an exemplary embodiment of the present disclosure, before solving the sending-end precoding matrix, the method further includes: and solving the Lagrangian multiplier.

In one exemplary embodiment of the present disclosure, performing downlink transmission based on the plurality of precodes includes: and transmitting the plurality of precodes to a receiving end through a downlink channel of the satellite.

According to an aspect of the present disclosure, there is provided a downlink transmission apparatus for satellite communication, the apparatus including: the satellite communication system comprises a construction module, a communication module and a communication module, wherein the construction module is used for constructing a beam edge user group of satellite communication, and the beam edge user group comprises a plurality of users; a user group module, configured to divide a plurality of users in the beam edge user group into a plurality of coding user groups; the distribution module is used for distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; the pre-coding module is used for generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; a transmitting module configured to perform downlink transmission based on the plurality of precodes.

According to an aspect of the present disclosure, an electronic device is provided, the electronic device including: one or more processors; storage means for storing one or more programs; when executed by one or more processors, cause the one or more processors to implement a method as above.

According to an aspect of the disclosure, a computer-readable medium is proposed, on which a computer program is stored, which program, when being executed by a processor, carries out the method as above.

According to the downlink transmission method, the downlink transmission device, the electronic equipment and the computer-readable medium for satellite communication disclosed by the invention, a beam edge user group for satellite communication is constructed, wherein the beam edge user group comprises a plurality of users; dividing a plurality of users in the beam edge user group into a plurality of coding user groups; distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; the downlink transmission mode based on the plurality of precodes can orthogonalize the satellite communication mobile channel, play a role in inhibiting interference combination and acquire better channel capacity performance.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings. The drawings described below are merely some embodiments of the present disclosure, and other drawings may be derived from those drawings by those of ordinary skill in the art without inventive effort.

Fig. 1 is a block diagram illustrating a system for satellite communications according to an exemplary embodiment.

Fig. 2 is a flow chart illustrating a downlink transmission method for satellite communication according to an example embodiment.

Fig. 3 is a flowchart illustrating a downlink transmission method for satellite communication according to another exemplary embodiment.

Fig. 4 is a flowchart illustrating a downlink transmission method for satellite communication according to another exemplary embodiment.

Fig. 5 is a diagram illustrating a comparison of multiuser channel capacities for a downlink transmission method for satellite communications in accordance with an example embodiment.

Fig. 6A and 6B are diagrams illustrating user channel capacity under different shadowing conditions of a downlink transmission method for satellite communication according to an exemplary embodiment.

Fig. 7 is a block diagram illustrating a downlink transmission apparatus for satellite communication according to an example embodiment.

FIG. 8 is a block diagram illustrating an electronic device in accordance with an example embodiment.

FIG. 9 is a block diagram illustrating a computer-readable medium in accordance with an example embodiment.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus, a repetitive description thereof will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the subject matter of the present disclosure can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the disclosure.

The block diagrams shown in the figures are functional entities only and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor means and/or microcontroller means.

The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first component discussed below may be termed a second component without departing from the teachings of the disclosed concept. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It is to be understood by those skilled in the art that the drawings are merely schematic representations of exemplary embodiments, and that the blocks or processes shown in the drawings are not necessarily required to practice the present disclosure and are, therefore, not intended to limit the scope of the present disclosure.

Fig. 1 is a block diagram illustrating a system for satellite communications according to an exemplary embodiment. As shown in fig. 1, the upper half of the figure is a transmitting section, and the lower half is a receiving section, where transmitted data input by the transmitting section is a binary number. The basic functional blocks of the OFDM baseband system have been included, i.e., constellation mapping, demapping, serial-to-parallel conversion, parallel-to-serial conversion, IFFT/FFT, CP (cyclic prefix) addition, CP removal, time synchronization, frequency synchronization, channel estimation and equalization.

In one embodiment, the design requirements of the communication system are:

1. bit rate 400 kbps;

2. the time delay is 20 mus;

3. the bandwidth is less than 200 KHz;

when a system is designed, specific system parameters need to be designed in a simulation mode according to the requirements of the system, the requirements of the system need to be met during design, the implementation possibility needs to be fully considered, and compromise is sought in multiple conflicts. The method comprises the following specific steps:

1. determining the size of the guard interval, i.e. T, from the maximum delay spread_gThe size of (d);

by convention, the general guard interval T_gIs selected to be two to four times the root mean square of the delay spread 2]Or the maximum delay spread (maximum delay spread)Less than the guard interval). The design first gets T_gDelay spread equal to 4 times, i.e. T_g＝20μs。

2. To obtain T_gThen, the symbol period of one OFDM can be calculated, i.e. T_sym=T_g+ T, wherein T_symIs the symbol period and T is the useful signal length, typically the symbol length is chosen to be five to six times the guard interval. The selection in this design is 6 times, i.e. 480 mus, so that the useful signal length is 400 mus and the subcarrier spacing is 2.5 KHz.

3. Determining the number of subcarriers and a constellation mapping mode;

(1) the transmission bit number of each OFDM symbol = OFDM system bit rate/OFDM symbol rate, and 192 bits are calculated;

(2) if a QPSK mapping mode is adopted, each subcarrier transmits 2 bits, the number of the calculated subcarriers is 96, and thus the signal bandwidth is 2.5KHz multiplied by 96=240KHz > 200KHz and does not meet the requirement; if 16QAM mapping is adopted, each subcarrier transmits 4 bits, the number of required subcarriers is 48, the signal bandwidth is 2.5KHz multiplied by 48=120KHz < 200KHz, and the requirement is met, so the design adopts 16QAM mapping.

4. Determining sampling frequencies of FFT and IFFT;

since the number of subcarriers is 48, the number of FFT points is 64 points (the number of FFT points can only be raised to an integer power of 2), the sampling frequency is 64/400 μ s =160KHz, and the number of sampling points is 76.8 in one symbol time. Since the number of sampling points must be an integer within the conversion time and symbol interval, the parameters determined in the above three steps need to be adjusted according to this point. Taking the number of sampling points as 80, the sampling rate is 166.67KHz, the FFT computation time is 64/166.67KHz =384us guard interval, and the subcarrier interval is respectively equal to:

480us-384us=96us>80us，

1/384us =2.604KHz >2.5KHz, meeting the requirements.

The specific simulation implementation process can be as follows:

firstly, the basic functions of the OFDM system are realized through simulation, namely, a transmitting part and a receiving part are simulated under the condition of not adding noise and channels, and a constellation diagram and a frequency spectrum diagram of a transmitting end and a constellation diagram and an error rate after demodulation of a receiving end are obtained. If the constellation diagram of the receiving end is completely consistent with the transmitting end (namely consistent with the theoretical constellation diagram of the corresponding mapping mode) and the bit error rate is zero, the basic modulation and demodulation function of the system can be correctly realized.

Second, gaussian white noise (AWGN) is added. Firstly, on the basis of the first step, given signal-to-noise ratio, Gaussian white noise is added to a transmitting data stream for simulation. If the constellation diagram after the received data demodulation is only less concentrated in constellation points compared with the transmitting end, the correctness of the first step is preliminarily proved. Secondly, after a correct constellation diagram is obtained at a receiving end, the range of the signal-to-noise ratio is set, the error rate of the system is simulated under different signal-to-noise ratios, an error rate curve is obtained and is compared with a theoretical error rate curve, if the error rate curve obtained through simulation tends to be consistent with the theory, the addition of a noise component is correct, and the system can normally work under the condition of Gaussian white noise.

And thirdly, simulating the system performance by the transmitted data through a multipath Rayleigh fading channel. First, parameters of multipath Rayleigh fading are set, transmission data is allowed to pass through the channel, and Gaussian white noise is added. Assuming that the receiving end knows channel information, carrying out frequency domain equalization at the receiving end according to channel parameters, and obtaining a receiving end constellation diagram and an error rate curve through simulation, wherein if the error rate curve is consistent with a Rayleigh channel theoretical error rate curve, the Rayleigh fading channel addition is correct, and the system is reasonable in design and can work normally under a multipath Rayleigh fading channel.

And fourthly, performing channel estimation and equalization. And on the basis of the third step, assuming that the channel parameters of the receiving end are unknown, carrying out channel estimation according to the received training sequence, and obtaining the error rate curve of the system at the moment, wherein the error rate is slightly higher than a theoretical value due to estimation errors.

Fig. 2 is a flow chart illustrating a downlink transmission method for satellite communication according to an example embodiment. The downlink transmission method 20 for satellite communication includes at least steps S202 to S208.

As shown in fig. 2, in S202, a beam edge user group for satellite communication is constructed, the beam edge user group including a plurality of users. More specifically, a group of beam-edge users may be constructed based on the distance of the user from the center of the beam.

The satellite communication area can be divided into a plurality of cells, users in each cell are randomly distributed, and the users higher than the threshold are defined as satellite edge users by comparing the ratio of the satellite signal power of the cell received by the users and the power of the interference satellite of the adjacent cell with a preset threshold.

In S204, a plurality of users in the beam edge user group are divided into a plurality of encoded user groups. In one embodiment, one may for example: extracting a first user and a second user from a plurality of users in the beam edge user group; generating a coded user group by the first user and the second user; and when all the users in the beam edge user group are extracted, generating the plurality of coding user groups.

According to the first predetermined characteristic, a first user is determined in the beam edge user group, then according to the second predetermined characteristic, a second user is determined in the beam edge user group, and the first user and the second user are allocated to a coding user group. The user identifications of the two users are deleted in the beam edge user group so as to avoid repeated use in the subsequent steps. And continuing to iterate according to the steps until all the users are screened.

In S206, the same frequency point is allocated to the user in each of the plurality of encoded user groups. And allocating the same frequency points to the first user and the second user in each coding user group in the plurality of coding user groups.

In an embodiment, the process of allocating the frequency may be iteratively completed at the same time as the step of extracting the first user and the second user, or the frequency may be agreed to be allocated after the encoded user group is generated, which is not limited in this application.

In one embodiment, the first user and the second user may be selected in sequence and allocated the same frequency for subsequent precoding. After all users are paired and allocated with frequencies, the iteration step is ended, and a plurality of coding user groups are obtained, wherein the coding user groups comprise a first user and a second user and can also comprise the same frequency allocated to the first user and the second user. The first user and the second user in each coding user group are allocated with the same frequency, and the frequencies of different coding user groups are different.

In S208, multiple precodes are generated for the users based on the same frequency points of the users in each coding user group. For example, equivalent channel matrixes are respectively constructed for the user groups based on the same frequency points of the users in each user group; generating a plurality of precodes based on a plurality of equivalent channel matrices;

the specific content of "generating multiple precodes for users based on the same frequency points of the users in each coding user group" will be described in detail in the embodiment corresponding to fig. 4.

In S210, downlink transmission is performed based on the plurality of precodes. The plurality of precodes may be transmitted to a receiving end through a downlink channel of the satellite.

Precoding techniques have generally been developed in conjunction with multiple-input multiple-output (MIMO) techniques, which, in short, employ multiple transmit antennas at a base station, and which dates back to the 1970 s at the earliest. The MIMO technology can bring space diversity and multiplexing, and improve the reliability and channel gain of data transmission. In the conventional single-antenna system, signals are sent to a terminal in a broadcasting manner, and signal energy is radiated to the periphery, so that not only is energy wasted, but also a user cannot be guaranteed to receive high-quality signals.

Typical advantages of precoding are: 1. the signal processing is carried out at the base station, so that users can directly receive data required by the users, and the signal processing of a terminal is avoided; 2. the precoding enables the signals sent by the base station to have directivity instead of pure peripheral radiation, so that the power of the signals received by the user is enhanced, meanwhile, the energy waste is avoided, and the energy efficiency of the communication system is improved.

According to the downlink transmission method for satellite communication, a beam edge user group of the satellite communication is constructed, wherein the beam edge user group comprises a plurality of users; dividing a plurality of users in the beam edge user group into a plurality of coding user groups; distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; the downlink transmission mode based on the plurality of precodes can orthogonalize the satellite communication mobile channel, play a role in inhibiting interference combination and acquire better channel capacity performance.

It should be clearly understood that this disclosure describes how to make and use particular examples, but the principles of this disclosure are not limited to any details of these examples. Rather, these principles can be applied to many other embodiments based on the teachings of the present disclosure.

Fig. 3 is a flowchart illustrating a downlink transmission method for satellite communication according to another exemplary embodiment. The process 30 shown in fig. 3 is a detailed description of the process S204 "dividing the plurality of users in the beam edge user group into a plurality of encoded user groups" in the process shown in fig. 2.

As shown in fig. 3, in S302, the farthest user in the beam edge user group is sequentially extracted as the first user. And determining the farthest user in the current beam edge user group through distance comparison, and setting a specific identifier for the user as a first user. The satellite cell farthest end user may be determined, for example, based on an average of the signal power received by the user.

In S304, the farthest user of the adjacent sub-areas of the adjacent beams in the beam edge user group is sequentially extracted as the second user. And determining the farthest user in the current beam edge user group through distance comparison between adjacent subareas, and setting a specific identifier for the user as a second user.

In S306, a group of encoded users is generated by the first user and the second user. And setting a joint identifier for the first user and the second user to indicate that the first user and the second user are in the same coding user group. Users in the same code group may also be assigned the same frequency.

In S308, the selected users are deleted from the group of beam edge users. And sequentially extracting all users in the wave beam edge user group, distributing identifications for the users one by one, and establishing a coding user group. After the identification is allocated to the user group, namely the coding user group is allocated to the user group, the user group is deleted in the beam edge user group so as to avoid the subsequent repeated extraction.

In S310, whether the beam edge user group is empty. And judging whether unprocessed users exist in the beam edge user group at the moment, finishing the processing of all the users in the beam edge user group, and performing subsequent steps when no remaining users exist, otherwise, continuing to extract.

In S312, the plurality of encoded user groups are generated.

Fig. 4 is a flowchart illustrating a downlink transmission method for satellite communication according to another exemplary embodiment. The process 40 shown in fig. 4 is a detailed description of "generating multiple precodes for users based on the same frequency points of the users in each coding user group" in S208 in the process shown in fig. 2.

As shown in fig. 4, in S402, equivalent channel matrices are respectively constructed for the plurality of user groups based on the same frequency points of the users in each user group.

More specifically, the equivalent channel matrix is a product of a space mapping matrix used by the transmitter and a channel matrix, and under the condition that the transmitting end knows an ideal state of channel information or obtains the channel state information through channel estimation, the channel information matrix H is properly decomposed, so that a corresponding transmitting end precoding matrix, a receiving end equalization matrix and an equivalent channel matrix for converting a channel into a plurality of independent sub-channels are obtained.

In S404, the transmitting-end precoding matrix is initialized based on the equivalent channel matrix. The TD-LTE downlink transmission adopts a physical layer framework of MIMO-OFDM, and a plurality of (4 at most) data streams are transmitted in parallel through 4 transmitting antennas at most, so that the peak transmission rate can be effectively improved. In the physical layer processing process of LTE, precoding is a core function module thereof, and several main transmission modes of a physical downlink shared channel are implemented by precoding. In the MIMO system, when the transmitting end cannot obtain any Channel State Information (CSI), the power and transmission rate are equally allocated to each parallel data stream and an omni-directional transmission mode is respectively adopted, so that the optimal performance can be obtained.

In S406, the lagrangian multiplier is solved. The basic lagrangian multiplier method (also called lagrangian multiplier method) is a method of solving an extremum of the function f (x1, x 2.) =0 under the constraint of g (x1, x 2.) = 0. The main idea is to introduce a parameter lambda (i.e. Lagrange multiplier), link the constraint condition function with the primary function, and make it possible to formulate an equation equal to the number of variables, thereby solving the solution of each variable to obtain the extreme value of the primary function.

In S408, the transmit-end precoding matrix is solved.

In S410, when the solution of the transmit-end precoding matrix satisfies the condition, the precoding is generated. The precoding scheme may be generated at the end of an iteration, for example, when the difference in the iteration is less than a threshold.

A group of satellite beam users as described in figure 5 is computed according to the method of the present application,

1. a bit rate of 400;

2. the delay is 20;

3. the bandwidth is less than 200;

according to the requirements of the system, the specific system parameters are designed as shown in the table:

the simulation results of the precoding scheme calculated by the system and the multi-user channel capacity under different shadowing conditions are shown in fig. 6A and fig. 6B, and it can be known from the figures that the method in the present application can expand the user channel capacity under different conditions.

Those skilled in the art will appreciate that all or part of the steps implementing the above embodiments are implemented as computer programs executed by a CPU. When executed by the CPU, performs the functions defined by the above-described methods provided by the present disclosure. The program may be stored in a computer readable storage medium, which may be a read-only memory, a magnetic or optical disk, or the like.

Furthermore, it should be noted that the above-mentioned figures are only schematic illustrations of the processes involved in the methods according to exemplary embodiments of the present disclosure, and are not intended to be limiting. It will be readily understood that the processes shown in the above figures are not intended to indicate or limit the chronological order of the processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, e.g., in multiple modules.

The following are embodiments of the disclosed apparatus that may be used to perform embodiments of the disclosed methods. For details not disclosed in the embodiments of the apparatus of the present disclosure, refer to the embodiments of the method of the present disclosure.

Fig. 7 is a block diagram illustrating a downlink transmission apparatus for satellite communication according to an example embodiment. As shown in fig. 7, the downlink transmission apparatus 70 for satellite communication includes: a building module 702, a user group module 704, an allocation module 706, a pre-coding module 708, and a sending module 710.

The construction module 702 is configured to construct a beam edge user group for satellite communication, where the beam edge user group includes a plurality of users; the construction module 702 can construct a group of beam edge users based on the distance of the users from the center of the beam.

A user group module 704 for dividing a plurality of users in the beam edge user group into a plurality of encoded user groups; the user group module 704 is further configured to extract a first user and a second user of the plurality of users in the beam-edge user group; generating a coded user group by the first user and the second user; and when all the users in the beam edge user group are extracted, generating the plurality of coding user groups.

The allocating module 706 is configured to allocate the same frequency point to users in each of the multiple coding user groups; the allocating module 706 is further configured to allocate the same frequency point to the first user and the second user in each of the multiple encoded user groups.

The pre-coding module 708 is configured to generate multiple pre-codes for the users based on the same frequency point of the users in each coding user group; the pre-coding module 708 is further configured to construct equivalent channel matrices for the multiple user groups respectively based on the same frequency point of the users in each user group; generating a plurality of precodes based on a plurality of equivalent channel matrices;

a transmitting module 710 is configured to perform downlink transmission based on the plurality of precodes. The transmitting module 710 is further configured to transmit the plurality of precodes to a receiving end through a downlink channel of the satellite.

According to the downlink transmission device for satellite communication of the present disclosure, a beam edge user group for satellite communication is constructed, the beam edge user group including a plurality of users; dividing a plurality of users in the beam edge user group into a plurality of coding user groups; distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; the downlink transmission mode based on the plurality of precodes can orthogonalize the satellite communication mobile channel, play a role in inhibiting interference combination and acquire better channel capacity performance.

FIG. 8 is a block diagram illustrating an electronic device in accordance with an example embodiment.

An electronic device 800 according to this embodiment of the disclosure is described below with reference to fig. 8. The electronic device 800 shown in fig. 8 is only an example and should not bring any limitations to the functionality and scope of use of the embodiments of the present disclosure.

As shown in fig. 8, electronic device 800 is in the form of a general purpose computing device. The components of the electronic device 800 may include, but are not limited to: at least one processing unit 810, at least one memory unit 820, a bus 830 connecting the various system components (including the memory unit 820 and the processing unit 810), a display unit 840, and the like.

Wherein the storage unit stores program code that can be executed by the processing unit 810, such that the processing unit 810 performs the steps according to various exemplary embodiments of the present disclosure described in this specification. For example, the processing unit 810 may perform the steps as shown in fig. 2, 3, 4.

The memory unit 820 may include readable media in the form of volatile memory units such as a random access memory unit (RAM) 8201 and/or a cache memory unit 8202, and may further include a read only memory unit (ROM) 8203.

The memory unit 820 may also include a program/utility 8204 having a set (at least one) of program modules 8205, such program modules 8205 including, but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may comprise an implementation of a network environment.

Bus 830 may be any of several types of bus structures including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

The electronic device 800 may also communicate with one or more external devices 800' (e.g., keyboard, pointing device, bluetooth device, etc.) such that a user can communicate with devices with which the electronic device 800 interacts, and/or any devices (e.g., router, modem, etc.) with which the electronic device 800 can communicate with one or more other computing devices. Such communication may occur via input/output (I/O) interfaces 850. Also, the electronic device 800 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network, such as the internet) via the network adapter 860. The network adapter 860 may communicate with other modules of the electronic device 800 via the bus 830. It should be appreciated that although not shown, other hardware and/or software modules may be used in conjunction with the electronic device 800, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, among others.

Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, as shown in fig. 9, the technical solution according to the embodiment of the present disclosure may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which may be a personal computer, a server, or a network device, etc.) to execute the above method according to the embodiment of the present disclosure.

The software product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

The computer readable storage medium may include a propagated data signal with readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A readable storage medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Program code for carrying out operations for the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., through the internet using an internet service provider).

The computer readable medium carries one or more programs which, when executed by a device, cause the computer readable medium to perform the functions of: constructing a beam edge user group of satellite communication, wherein the beam edge user group comprises a plurality of users; dividing a plurality of users in the beam edge user group into a plurality of coding user groups; distributing the same frequency points for the users in each coding user group in the plurality of coding user groups; generating a plurality of pre-codes for the users based on the same frequency points of the users in each coding user group; performing downlink transmission based on the plurality of precodes.

Those skilled in the art will appreciate that the modules described above may be distributed in the apparatus according to the description of the embodiments, or may be modified accordingly in one or more apparatuses unique from the embodiments. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.

Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, the technical solution according to the embodiments of the present disclosure may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which may be a personal computer, a server, a mobile terminal, or a network device, etc.) to execute the method according to the embodiments of the present disclosure.

Exemplary embodiments of the present disclosure are specifically illustrated and described above. It is to be understood that the present disclosure is not limited to the precise arrangements, instrumentalities, or instrumentalities described herein; on the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.