CN113271558A - Internet of things information transmission method, terminal and system in low-orbit satellite Internet of things - Google Patents
Internet of things information transmission method, terminal and system in low-orbit satellite Internet of things Download PDFInfo
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Abstract
The invention discloses a method, a terminal and a system for transmitting Internet of things information in a low-orbit satellite Internet of things. The transmission method comprises the following steps: when the satellite is not connected with the ground station, the information of the Internet of things is transmitted in a store-and-forward mode; the store-and-forward mode includes: the terminal sends the Internet of things information to the target satellite based on the preset information, the target satellite stores the received Internet of things information, and when at least one of the target satellites and the ground station are changed from an unconnected state to a connected state, the target satellite transmits the stored Internet of things information to the network side for processing through the ground station; the preset information comprises ephemeris and terminal uplink frequency resources. By adopting the mode of presetting information by the terminal, the terminal message sending can be realized under the condition that the satellite is not connected with the ground station and the message interaction is not carried out with the network side, the problem that the air interface frequency resource is wasted because the terminal does not send the message when the satellite is not connected with the ground station is solved, and the utilization rate of the air interface resource is effectively improved.
Description
Technical Field
The invention relates to the technical field of low-earth-orbit satellite internet of things, in particular to a method, a terminal and a system for transmitting internet of things information in the low-earth-orbit satellite internet of things.
Background
With the rapid development of information technology, the development of the low-orbit satellite internet of things is very rapid, and the research on the transmission mechanism of the satellite internet of things is very wide. In the existing transmission mechanism of the satellite internet of things, when a satellite is connected with a ground station, a terminal in a satellite beam coverage range can timely obtain system information of a network side forwarded by the satellite, the internet of things information can be well sent based on the system information, and data of the terminal is uploaded to the satellite and then forwarded to the ground station by the satellite in real time; when the satellite and the ground station are not connected, because the network side cannot send system information to the terminal, the ground station cannot schedule resources for the terminal, the terminal cannot obtain the relevant configuration information of the network side and the satellite beam information, and the terminal cannot send messages even if the terminal is in the satellite beam coverage range, thereby greatly wasting air interface frequency resources of the terminal of the internet of things.
Disclosure of Invention
The invention aims to at least solve the technical problems in the prior art, and particularly provides an Internet of things information transmission method, terminal and system in a low-orbit satellite Internet of things.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a method for transmitting information of an internet of things in a low earth orbit satellite internet of things, wherein when a satellite is not connected to a ground station, a store-and-forward mode is used to transmit the information of the internet of things; the store-and-forward mode comprises: the method comprises the steps that a terminal sends internet of things information to a target satellite based on preset information, the target satellite stores the received internet of things information, and when at least one of the target satellites and a ground station are changed from an unconnected state to a connected state, the target satellite transmits the stored internet of things information to a network side for processing through the ground station; the preset information comprises ephemeris and terminal uplink frequency resources.
The technical scheme is as follows: the method aims at the problem that when a satellite and a ground station are not connected (including but not limited to a connection interruption scene or a scene of connection for the first time), a terminal cannot obtain network side system information (such as network configuration information and accessible satellite beam information) and cannot send information, so that air interface frequency resources of the terminal are wasted.
In a preferred embodiment of the invention, when the connection between the satellite and the ground station is interrupted, the mode is switched to a store-and-forward mode to transmit the information of the internet of things, and when the connection between the satellite and the ground station is recovered, the mode is switched back to a normal mode to transmit the information of the internet of things; in the normal mode, the terminal sends the internet of things information to the satellite based on the system information sent by the network side in real time, the satellite forwards the received internet of things information to the network side, and the system information comprises an accessible satellite beam, an application layer key and a network layer key.
The technical scheme is as follows: two Internet of things information transmission modes are set, and the satellite and the ground station correspond to different transmission modes in different connection states, so that the Internet of things information can be uploaded only under the coverage of satellite beams by the terminal, and the waste of air interface frequency resources of the terminal is reduced.
In a preferred embodiment of the present invention, the internet of things information uploaded by the terminal in the store-and-forward mode and the normal mode adopts the same data format.
The technical scheme is as follows: the complexity of the whole satellite Internet of things system and the network side is reduced.
In a preferred embodiment of the present invention, in the store-and-forward mode, the terminal sends the same piece of information of the internet of things multiple times, and performs frequency offset compensation on the information of the internet of things by using different frequency compensation amounts during each sending.
The technical scheme is as follows: the probability that the terminal sends the uplink Internet of things information to the target satellite receiving window is greatly improved, the Internet of things information is effectively received by the target satellite, the uplink information is sent for multiple times when different frequencies are pre-compensated, and the satellite receiving probability and the time-frequency resource using condition are integrated.
In a preferred embodiment of the present invention, the sending, by the terminal, the internet of things information to the target satellite based on the preset information specifically includes: predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time, and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource; calculating frequency deviation compensation quantity according to the ephemeris; calculating the sending time lead by using the distance between the terminal and the target satellite; and performing frequency offset compensation on the information to be uploaded based on the frequency offset compensation amount, and sending the information after the frequency offset compensation in advance according to the sending time lead.
The technical scheme is as follows: the terminal can compensate time and frequency according to the current time and position so as to improve the receiving possibility of the target satellite receiving window.
In a preferred embodiment of the present invention, the terminal sends the internet of things information to the target satellite based on the preset information, and further includes: the information of the Internet of things comprises terminal identifications corresponding to the terminals one by one; the preset information also comprises a preset application layer key, a preset network layer key and a terminal identifier; encrypting a data field in the information of the Internet of things by using a preset application layer key, and performing integrity protection on the whole information of the Internet of things by using a preset network layer key; and uploading the information added with the terminal identification as the information to be uploaded to the satellite.
The technical scheme is as follows: by adopting the mode of presetting the key, a safety protection mechanism can be realized under the condition of not negotiating with a network, and the safety protection of the uplink message of the Internet of things under the store-and-forward mode is enhanced.
In a preferred embodiment of the present invention, when the terminal sends the same piece of information about the internet of things multiple times, and performs frequency offset compensation on the information about the internet of things by using different frequency compensation amounts during each sending, the terminal sends the information about the internet of things to the target satellite based on preset information, which specifically includes: predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time, and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource; for the same piece of information of the Internet of things, calculating Doppler frequency offsets of different target sending time points according to ephemeris, and setting frequency offset compensation quantity of the target sending time points by taking the Doppler frequency offsets of the target sending time points as a central point; calculating the sending time lead of the target sending time point by using the distance between each target sending time point terminal and a target satellite; and for each target sending time point, carrying out frequency offset compensation on the information to be uploaded based on the frequency offset compensation amount of the target sending time point, and sending the information after frequency offset compensation in advance according to the sending time lead of the target sending time point.
The technical scheme is as follows: the method and the device particularly realize that a plurality of target sending time points send the same Internet of things information by adopting different frequency offset compensation amounts, and the time and frequency compensation is carried out at the same time in each sending, so that the possibility that the satellite receives the uplink Internet of things information in a store-and-forward mode is increased.
In a preferred embodiment of the present invention, the transmission time advance t of each target transmission time point is calculated based on the following formula by using the distance between the terminal and the target satellite at the target transmission time point0：t0L/C, where L denotes a distance between the terminal and the target satellite at the target transmission time point, and C denotes a speed of light.
The technical scheme is as follows: the transmission time advance can be rapidly acquired.
In a preferred embodiment of the present invention, setting a frequency offset compensation amount of a target transmission time point by using a doppler frequency offset of the target transmission time point as a central point specifically includes: obtaining real-time Doppler frequency offset f of target sending time pointMultiple purposeAnd the frequency deviation (-f) of the terminal crystal oscillatorFinal (a Chinese character of 'gan'),+fFinal (a Chinese character of 'gan')) Frequency deviation (-f) of satellite crystal oscillatorToilet,+fToilet) Satellite reception frequency tolerance (-f)0,+f0) (ii) a Sending the targetThe frequency deviation compensation quantity at the time point is set as fMultiple purposeOr fMultiple purpose±[f0-(fFinal (a Chinese character of 'gan')+fToilet)]Or
The technical scheme is as follows: the frequency compensation quantity required to be adjusted by the terminal comprises two parts of Doppler frequency offset and system frequency offset, and the frequency offset compensation accuracy can be improved.
In a preferred embodiment of the present invention, when the satellite is connected to a ground station, the satellite transmits the stored information of the internet of things to a network side for processing through the ground station, which specifically includes: the network side performs repeated data filtering processing on the received Internet of things information, a network layer key and an application layer key are obtained according to a terminal identifier in the information after the repeated data filtering processing, integrity verification is performed on the information after the repeated data filtering processing through the network layer key, and after the integrity verification is passed, a data field in the information after the repeated data filtering processing is decrypted through the application layer key.
The technical scheme is as follows: repeated data is filtered, repeated processing is avoided, information integrity protection of the Internet of things is achieved, and safety is improved.
In order to achieve the above object, according to a second aspect of the present invention, there is provided a terminal for an internet of things of a low earth orbit satellite, the terminal uploading information of the internet of things to the satellite based on a store-and-forward mode when the satellite is not connected to a ground station; the terminal includes: the system comprises a presetting module, a sending module and a receiving module, wherein the presetting module is used for presetting ephemeris, terminal uplink frequency resources, terminal identifiers which correspond to terminals one to one, application layer keys and network layer keys; the satellite beam selection module is used for predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource; the positioning module is used for acquiring the real-time position of the terminal; the sending time lead acquisition module calculates the sending time lead by using the distance between the terminal and the target satellite; the frequency offset compensation quantity acquisition module is used for calculating frequency offset compensation quantity according to the ephemeris; the terminal sending module is used for encrypting data fields in the information of the Internet of things by using an application layer key and carrying out integrity protection on the whole information of the Internet of things by using a preset network layer key, wherein the information of the Internet of things comprises terminal identifications corresponding to the terminals one by one; and performing frequency offset compensation on the information subjected to integrity protection based on the frequency offset compensation amount, and transmitting the information subjected to frequency offset compensation to a satellite before transmitting the time advance.
The technical scheme is as follows: the terminal adopts a terminal preset information mode, can realize terminal message sending under the condition that the satellite is not connected with the ground station and does not perform message interaction with the network side, and solves the problem that when the satellite is not connected with the ground station, the terminal does not send messages and wastes air interface frequency resources. Time and frequency compensation is carried out simultaneously during each transmission, and the possibility that the satellite receives the uplink Internet of things information in the store-and-forward mode is increased.
In order to achieve the above object, according to a third aspect of the present invention, there is provided a satellite for an internet of things of a low earth orbit satellite, the satellite storing and forwarding internet of things information uploaded by a terminal based on a store-and-forward mode when the satellite is not connected to a ground station; the satellite includes: the terminal information receiving module is used for receiving the Internet of things information uploaded by the terminal; the storage module is used for storing the Internet of things information uploaded by the terminal during the period that the satellite is not connected with the ground station; and the satellite sending module is used for forwarding the information of the Internet of things stored in the storage module to a network side through the ground station when the satellite and the ground station are changed from the unconnected state to the connected state.
The technical scheme is as follows: the satellite can store the Internet of things information in a storage and forwarding mode, and can realize terminal message sending under the condition that the satellite is not connected with the ground station, so that the problem that air interface frequency resources are wasted because no message is sent by the terminal when the satellite is not connected with the ground station is solved.
In order to achieve the above object, according to a third aspect of the present invention, the present invention provides a low earth orbit satellite internet of things system, including a terminal, at least one satellite, a ground station, and a network side device, where when the satellite is not connected to the ground station, the terminal, the satellite, the ground station, and the network side device transmit internet of things information in a store-and-forward mode; the network side equipment comprises a network server, an application server and an application data server, wherein the network server filters repeated data of the received Internet of things information, a network layer key is obtained according to a terminal identifier in the information after the repeated data is filtered, integrity verification is carried out on the information after the repeated data is filtered through the network layer key, after the integrity verification is passed, a data field in the information after the repeated data is filtered is forwarded to the application server, the application server obtains the application layer key from a user data server, and the data field in the Internet of things information is decrypted through the application layer key.
The technical scheme is as follows: the system aims at the problem that when a satellite and a ground station are not connected (including but not limited to a connection interruption scene or a scene of connection for the first time), a terminal cannot obtain network side system information (such as network configuration information and accessible satellite beam information) and cannot send information, so that air interface frequency resources of the terminal are wasted.
Drawings
Fig. 1 is a schematic diagram of a process of sending information of the internet of things in a store-and-forward mode in an application scenario of the present invention;
fig. 2 is a diagram illustrating a transmission timing advance adjustment according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
The invention discloses an internet of things information transmission method in a low earth orbit satellite internet of things, which adopts a store-and-forward mode to transmit internet of things information when a satellite is not connected with a ground station; the store-and-forward mode includes: the terminal sends the Internet of things information to the target satellite based on the preset information, the target satellite stores the received Internet of things information, and when at least one of the target satellites and the ground station are changed from an unconnected state to a connected state, the target satellite transmits the stored Internet of things information to the network side for processing through the ground station; the preset information comprises ephemeris and terminal uplink frequency resources.
In this embodiment, the satellite and ground station disconnection is preferably, but not limited to, a scenario in which the satellite and ground station have not been connected for the first time or a scenario in which the satellite and ground station connection is interrupted. In the low-earth-orbit satellite Internet of things, the low-earth-orbit satellite Internet of things system comprises at least one satellite, the satellite and a terminal move relatively, and when a satellite beam covers the terminal, the terminal can communicate with the satellite to upload Internet of things information.
In this embodiment, the target satellite is preferably, but not limited to, a satellite whose satellite beam covers the terminal or a satellite whose satellite beam is to cover the terminal.
In this embodiment, when the satellite is connected to the ground station, the terminal, the satellite, the ground station, and the network side device form a complete satellite internet of things network, and the network side may send system information to the terminal through the satellite in real time. When the satellite is not connected with the ground station, the terminal cannot acquire system information, even if the satellite beam covers the system information, because the specific information of the satellite beam is unknown, an internet of things information uplink cannot be established, information cannot be sent, and air interface resources are wasted, therefore, the terminal can predict the frequency information of the satellite beam covering or covering the terminal at the current time by combining ephemeris and the current time through the preset ephemeris, and can select the satellite beam with a frequency in the preset terminal uplink frequency resource to establish the uplink so as to realize information sending.
In this embodiment, preferably, the terminal may consider to enter a state where the satellite and the ground station are not connected when the terminal does not receive the system information within a preset time, and the terminal automatically enters the store-and-forward mode. Further preferably, the preset time is one or more superframe times.
In a preferred embodiment, when the connection between the satellite and the ground station is interrupted, the mode is switched to a store-and-forward mode to transmit the information of the internet of things, and when the connection between the satellite and the ground station is recovered, the mode is switched back to a normal mode to transmit the information of the internet of things; in a normal mode, the terminal sends the Internet of things information to the satellite based on the system information sent by the network side in real time, the satellite forwards the received Internet of things information to the network side, and the system information comprises accessible satellite beam information, an application layer key and a network layer key.
In a preferred embodiment, in the store-and-forward mode, the terminal sends the same piece of information of the internet of things for multiple times, and performs frequency offset compensation on the information of the internet of things by using different frequency compensation amounts during each sending.
In the embodiment, because the currently accessible satellite beam information obtained through the ephemeris is a static acquisition mode, and the currently accessible satellite beam information obtained through the system information sent by the network side is a dynamic acquisition mode, the dynamic acquisition mode is monitored in real time, so that the information accuracy is higher.
In a preferred embodiment, the sending, by the terminal, the internet of things information to the target satellite based on the preset information specifically includes: predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time, and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource; calculating frequency deviation compensation quantity according to the ephemeris; calculating the sending time lead by using the distance between the terminal and the target satellite; and performing frequency offset compensation on the information to be uploaded based on the frequency offset compensation amount, and sending the information after the frequency offset compensation in advance according to the sending time lead.
In this embodiment, the current position of the target satellite, the current velocity of the target satellite, and the frequency information of the beam of the target satellite can be obtained according to ephemeris and the current time, the beam of the target satellite conforming to the preset uplink frequency resource of the terminal is used as an accessible beam, the position and the velocity of the terminal can be obtained according to a positioning module of the terminal, and then the doppler frequency offset is obtained, the doppler frequency offset or the upper and lower small-amplitude floating values of the doppler frequency offset can be used as the frequency offset compensation amount, and the doppler frequency offset is specifically calculated as the prior art, such as the website https: the disclosure of// baike. ***. com/item/% E5% A4% 9A% E6% 99% AE% E5% 8B% 92% E9% A2% 91% E7% A7% BB/2585005fr ═ aladdin, which is not described in detail herein. The distance of the terminal from the target satellite may be obtained based on the terminal position and the target satellite position.
In a preferred embodiment, the terminal sends the information of the internet of things to the target satellite based on the preset information, and further includes: the information of the Internet of things comprises terminal identifications corresponding to the terminals one by one; the preset information also comprises a preset application layer key, a preset network layer key and a terminal identifier; encrypting a data field in the information of the Internet of things by using a preset application layer key, and performing integrity protection on the whole information of the Internet of things by using a preset network layer key; and uploading the information subjected to integrity protection to a satellite as the information to be uploaded.
In this embodiment, preferably, a preset application layer key is used for encrypting a data field in the information of the internet of things based on the 128AES algorithm, and a preset network layer key is used for integrity protection of the whole information of the internet of things based on the 128AES algorithm.
In this embodiment, a data field in the internet of things information is encrypted by using a preset application layer key based on a 128AES algorithm, and the specific process includes:
1) resulting in a sequence of blocks Ai. The encrypted field is pld ═ AppData, and is divided into k blocks of 16 bytes in length, and there are insufficient padding 0 of 16 bytes, and pad16 indicates the number of padded bytes. Where k equals ceil (len (pid)/16) (rounded up), where i equals 1 … k.
2) And (4) encrypting the Ai. Encrypt block Ai, resulting in Si:
Si＝aes128＿encrypt(AppSKey，Ai)
3) resulting in an encrypted sequence of blocks S. The encryption sequence of the sequence of blocks Ai is:
S＝S1|S2|S3|…|Si
4) and outputting the ciphertext C. Xoring S with (pld | pad16) yields:
M＝(pld|pad16)xor S
ciphertext C is the first len (pid) bytes intercepted by M.
The process of decryption is similar to the encryption process. Firstly, an encrypted block sequence S is obtained by utilizing the steps of the encryption process, the S and (C | pad16) are subjected to exclusive OR, and the front len (C) byte after exclusive OR is intercepted to be the original text.
In this embodiment, the integrity protection of the whole piece of information of the internet of things by using a preset network layer key based on the 128AES algorithm specifically includes:
1) the transmitting end calculates B0, B0 ═ len (msg), and if the number of bytes is less than 16 bytes, 0 is added in front to fill up to 16 bytes.
2) The sending end performs the following operations:
cmac＝aes128＿cmac(NwkSKey，B0|msg)
in the process, after the last encryption operation is completed, the first 4 bytes of an output value are taken as a sending end to generate an integrity protection factor MIC.
3) And adding the generated integrity protection factor MIC to the message needing to be sent, and sending the message to the receiving end.
4) And the receiving end carries out integrity verification on the message after receiving the message, and if the verification fails, the message is discarded.
In a preferred embodiment, when the terminal sends the same piece of information of the internet of things for multiple times and performs frequency offset compensation on the information of the internet of things by using different frequency compensation amounts during each sending, the terminal sends the information of the internet of things to a target satellite based on preset information, which specifically includes:
predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time, and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource;
for the same piece of information of the Internet of things, calculating Doppler frequency offsets of different target sending time points according to ephemeris, and setting frequency offset compensation quantity of the target sending time points by taking the Doppler frequency offsets of the target sending time points as a central point;
calculating the sending time lead of the target sending time point by using the distance between each target sending time point terminal and the target satellite; the coverage time of the terminal of the Internet of things of the satellite every day is determined, the terminal can judge whether the satellite moves above the terminal (namely whether the target satellite appears) according to the stored ephemeris and the current time, and can predict the accessible target satellite beam to transmit the message. As shown in fig. 2, since the time reference point is based on the satellite, before the terminal sends the message, the position of the satellite needs to be determined according to the stored ephemeris, and the time advance is calculated according to the time, the self position and the satellite position. The terminal sends the message in advance according to the sending time advance, and the time synchronization between the terminal and the target satellite can be kept. In fig. 2, Burst1 on the terminal UE side indicates transmission before transmission time adjustment, Burst2 on the terminal UE side indicates transmission after transmission time adjustment is advanced, Burst1 on the satellite LEO side indicates reception before transmission time adjustment, and Burst2 on the satellite LEO side indicates reception after transmission time adjustment is advanced.
And for each target sending time point, carrying out frequency offset compensation on the information to be uploaded based on the frequency offset compensation quantity of the target sending time point, and sending the information after frequency offset compensation in advance according to the sending time lead of the target sending time point.
In this embodiment, preferably, the same piece of information of the internet of things is transmitted by a plurality of consecutive target transmission time points.
In the present embodiment, since the frequency reference point is based on the satellite, before the terminal sends the message, it is necessary to determine the position of the satellite from the stored ephemeris and calculate the frequency compensation amount according to the time, the self position, and the satellite position.
In a preferred embodiment, the transmission time advance t of the target transmission time point is calculated based on the following formula by using the distance between the terminal and the target satellite at each target transmission time point0：
t0L/C, where L denotes a distance between the terminal and the target satellite at the target transmission time point, and C denotes a speed of light.
In a preferred embodiment, setting the frequency offset compensation amount of the target transmission time point by using the doppler frequency offset of the target transmission time point as a central point specifically includes:
obtaining real-time Doppler frequency offset f of target sending time pointMultiple purposeAnd the frequency deviation (-f) of the terminal crystal oscillatorFinal (a Chinese character of 'gan'),+fFinal (a Chinese character of 'gan')) Frequency deviation (-f) of satellite crystal oscillatorToilet,+fToilet) Satellite reception frequency tolerance (-f)0,+f0)；
Setting the frequency deviation compensation quantity of a target sending time point as fMultiple purposeOr fMultiple purpose±[f0-(fFinal (a Chinese character of 'gan')+fToilet)]Or
In this embodiment, it is further preferable that the frequency offset compensation amount of multiple target sending time points corresponding to the same piece of internet of things information should be fMultiple purpose、fMultiple purpose±[f0-(fFinal (a Chinese character of 'gan')+fToilet)]、
And the middle circulation is alternately assigned so as to further improve the feasibility of uplink access. In order to increase the possibility that the satellite receives the uplink data in the store-and-forward mode, the same uplink data packet needs to be sent for multiple times, the time for sending the uplink data each time is inconsistent, real-time Doppler frequency offset is calculated during sending, and f is used respectivelyMultiple purpose、fMultiple purpose±[f0-(fFinal (a Chinese character of 'gan')+fToilet)]、
And carrying out frequency offset compensation. Presetting frequency resources at the terminal to ensure that the carrier interval of the distributed Internet of things is greater than
To avoid interference of the two carrier signals.
In a preferred embodiment, when the satellite is connected to the ground station, the satellite transmits the stored information of the internet of things to the network side for processing via the ground station, which specifically includes:
the network side performs repeated data filtering processing on the received Internet of things information, a network layer key and an application layer key are obtained according to a terminal identifier in the information after the repeated data filtering processing, integrity verification is performed on the information after the repeated data filtering processing through the network layer key, and after the integrity verification is passed, a data field in the information after the repeated data filtering processing is decrypted through the application layer key.
In this embodiment, the repeated data filtering process is to filter the repeated internet of things information data packets, and whether the repeated internet of things information data packets are the same data packets or not can be judged according to the name, the size, the header file and the like of the data packets, and only one data packet is left in a plurality of the same data packets for subsequent processing.
In this embodiment, it is preferable that at least one network layer key preset by the terminal and a one-to-one correspondence relationship between the terminal identifier and the network layer key preset by the terminal are preset in the network server. At least one application layer key preset by the terminal and the one-to-one corresponding relation between the terminal identification and the application layer key preset by the terminal are preset in the application server.
In an application scenario of the method for transmitting the internet of things information in the low earth orbit satellite internet of things provided by the invention, a specific flow diagram is shown in fig. 1, and the method specifically comprises the following steps:
a, presetting satellite ephemeris, a terminal unique identifier, a terminal temporary identifier, usable frequencies in a store-and-forward mode, a terminal application layer key AppSKey, a terminal network layer key NwkSKey and the like in a terminal in a store-and-forward mode;
and B, the terminal judges to enter a store-and-forward mode according to the fact that the terminal does not receive the system information in one or a plurality of superframes. When uplink data are sent, encrypting a data field in the message by using a preset application layer key AppSKey, and performing integrity protection on the whole message by using a preset network layer key NwkSKey;
c, the terminal predicts satellite beams which can be accessed according to preset ephemeris and current time, selects one satellite beam for accessing, selects preset frequency, and calculates the time advance and Doppler frequency offset of the terminal according to the time, the position of the terminal and the ephemeris;
d, using the terminal to send the time lead for time compensation, using Doppler frequency offset for frequency compensation, and sending an uplink Internet of things message to the satellite after compensation;
e, the satellite stores the received uplink Internet of things message, constructs an interface message of the satellite and the Internet of things network server when the satellite is connected with the ground network, and sends the message to the Internet of things network server;
step F, the Internet of things network server analyzes the interface message, the interface message is recombined into uplink data, the repeated data are filtered, a corresponding network layer secret key NwkSKey is found according to the terminal identification, and integrity check is carried out by using the network layer secret key NwkSKey;
g, after the verification is passed, forwarding the data field in the message to an application server;
and step H, the application server decrypts the data field by using the application layer key AppSKey, and the data can be used after decryption.
The invention also discloses a terminal for the low-orbit satellite Internet of things, and in a preferred embodiment, when the satellite is not connected with the ground station, the terminal uploads the Internet of things information to the satellite based on a store-and-forward mode;
the terminal includes: the system comprises a presetting module, a sending module and a receiving module, wherein the presetting module is used for presetting ephemeris, terminal uplink frequency resources, terminal identifiers which correspond to terminals one to one, application layer keys and network layer keys; the satellite beam selection module is used for predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource; the positioning module is used for acquiring the real-time position of the terminal, and the positioning module is preferably but not limited to a GPS module; the sending time lead acquisition module calculates the sending time lead by using the distance between the terminal and the target satellite; the frequency offset compensation quantity acquisition module is used for calculating frequency offset compensation quantity according to the ephemeris; the terminal sending module is used for encrypting data fields in the information of the Internet of things by using an application layer key and carrying out integrity protection on the whole information of the Internet of things by using a preset network layer key, wherein the information of the Internet of things comprises terminal identifications corresponding to the terminals one by one; and performing frequency offset compensation on the information subjected to integrity protection based on the frequency offset compensation amount, and transmitting and uploading the information subjected to frequency offset compensation to a satellite according to the transmission time advance.
The invention also discloses a satellite for the low-orbit satellite Internet of things, and in a preferred embodiment, when the satellite is not connected with the ground station, the satellite stores and forwards the Internet of things information uploaded by the terminal based on a store-and-forward mode;
the satellite includes: the terminal information receiving module is used for receiving the Internet of things information uploaded by the terminal; the storage module is used for storing the Internet of things information uploaded by the terminal during the period that the satellite is not connected with the ground station; and the satellite sending module is used for forwarding the information of the Internet of things stored in the storage module to the network side through the ground station when the satellite and the ground station are changed from the unconnected state to the connected state.
The invention also discloses a low-orbit satellite internet of things system, which comprises a terminal, at least one satellite, a ground station and network side equipment in a preferred embodiment, wherein when the satellite is not connected with the ground station, the terminal, the satellite, the ground station and the network side equipment adopt a store-and-forward mode to transmit internet of things information;
the network side equipment comprises a network server, an application server and a user data server, the network server performs repeated data filtering processing on received Internet of things information, a network layer key is obtained according to a terminal identifier in the information after the repeated data filtering processing, integrity verification is performed on the information after the repeated data filtering processing through the network layer key, after the integrity verification is passed, a data field in the information after the repeated data filtering processing is forwarded to the application server, the application server obtains the application layer key from the user data server, and the data field in the Internet of things information is decrypted through the application layer key.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. The method for transmitting the information of the Internet of things in the low earth orbit satellite Internet of things is characterized in that when a satellite is not connected with a ground station, the information of the Internet of things is transmitted in a store-and-forward mode;
the store-and-forward mode comprises: the method comprises the steps that a terminal sends internet of things information to a target satellite based on preset information, the target satellite stores the received internet of things information, and when at least one of the target satellites and a ground station are changed from an unconnected state to a connected state, the target satellite transmits the stored internet of things information to a network side for processing through the ground station; the preset information comprises ephemeris and terminal uplink frequency resources.
2. The method for transmitting the information of the internet of things in the internet of things of the low earth orbit satellite according to claim 1, wherein when the connection between the satellite and the ground station is interrupted, the mode is switched to a store-and-forward mode to transmit the information of the internet of things, and when the connection between the satellite and the ground station is recovered, the mode is switched back to a normal mode to transmit the information of the internet of things; in the normal mode, the terminal sends the Internet of things information to the satellite based on the system information sent by the network side in real time, the satellite forwards the received Internet of things information to the network side, and the system information comprises an accessible satellite beam, an application layer key and a network layer key;
and/or in a store-and-forward mode, the terminal sends the same Internet of things information for multiple times, and frequency offset compensation is carried out on the Internet of things information by adopting different frequency compensation quantities during each sending.
3. The method for transmitting the internet of things information in the internet of things of low earth orbit satellites as claimed in claim 1, wherein the terminal sends the internet of things information to the target satellite based on the preset information, and the method specifically comprises the following steps:
predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time, and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource;
calculating frequency deviation compensation quantity according to the ephemeris;
calculating the sending time lead by using the distance between the terminal and the target satellite;
and performing frequency offset compensation on the information to be uploaded based on the frequency offset compensation amount, and sending the information after the frequency offset compensation in advance according to the sending time lead.
4. The method for transmitting the internet of things information in the internet of things of low earth orbit satellites as claimed in claim 3, wherein the terminal sends the internet of things information to the target satellite based on the preset information, further comprising:
the information of the Internet of things comprises terminal identifications corresponding to the terminals one by one;
the preset information also comprises a preset application layer key, a preset network layer key and a terminal identifier;
encrypting a data field in the information of the Internet of things by using a preset application layer key, and performing integrity protection on the whole information of the Internet of things by using a preset network layer key;
and uploading the information subjected to integrity protection to a satellite as the information to be uploaded.
5. The method for transmitting the information of the internet of things in the internet of things of the low earth orbit satellite according to claim 2, wherein when the terminal sends the same information of the internet of things for multiple times and performs frequency offset compensation on the information of the internet of things by adopting different frequency compensation amounts during each sending, the terminal sends the information of the internet of things to the target satellite based on preset information, and specifically comprises:
predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time, and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource;
for the same piece of information of the Internet of things, calculating Doppler frequency offsets of different target sending time points according to ephemeris, and setting frequency offset compensation quantity of the target sending time points by taking the Doppler frequency offsets of the target sending time points as a central point;
calculating the sending time lead of the target sending time point by using the distance between each target sending time point terminal and a target satellite;
and for each target sending time point, carrying out frequency offset compensation on the information to be uploaded based on the frequency offset compensation amount of the target sending time point, and sending the information after frequency offset compensation in advance according to the sending time lead of the target sending time point.
6. The method for transmitting the information of the internet of things in the internet of things of low earth orbit satellites as claimed in claim 5, wherein the transmitting time lead t of each target transmitting time point is calculated by using the distance between each target transmitting time point terminal and a target satellite according to the following formula0：
t0L/C, wherein L represents a distance between the target transmission time point terminal and a target satellite, and C represents a speed of light;
and/or setting the frequency offset compensation quantity of the target sending time point by taking the Doppler frequency offset of the target sending time point as a central point, specifically comprising the following steps:
obtaining real-time Doppler frequency offset f of target sending time pointMultiple purposeAnd the frequency deviation (-f) of the terminal crystal oscillatorFinal (a Chinese character of 'gan'),+fFinal (a Chinese character of 'gan')) Frequency deviation (-f) of satellite crystal oscillatorToilet,+fToilet) Satellite reception frequency tolerance (-f)0,+f0)；
Setting the frequency offset compensation quantity of the target sending time point as fMultiple purposeOr fMultiple purpose±[f0-(fFinal (a Chinese character of 'gan')+fToilet)]Or
7. The method for transmitting the internet of things information in the internet of things of the low earth orbit satellite according to claim 5, wherein when the satellite is connected with the ground station, the satellite transmits the stored internet of things information to the network side for processing through the ground station, and specifically comprises the following steps:
the network side performs repeated data filtering processing on the received Internet of things information, a network layer key and an application layer key are obtained according to a terminal identifier in the information after the repeated data filtering processing, integrity verification is performed on the information after the repeated data filtering processing through the network layer key, and after the integrity verification is passed, a data field in the information after the repeated data filtering processing is decrypted through the application layer key.
8. A terminal for the Internet of things of a low-orbit satellite is characterized in that when the satellite is not connected with a ground station, the terminal uploads Internet of things information to the satellite based on a store-and-forward mode;
the terminal includes:
the system comprises a presetting module, a sending module and a receiving module, wherein the presetting module is used for presetting ephemeris, terminal uplink frequency resources, terminal identifiers which correspond to terminals one to one, application layer keys and network layer keys;
the satellite beam selection module is used for predicting a target satellite and an accessible target satellite beam according to a preset ephemeris and current time and selecting one access from the predicted accessible target satellite beam by combining with a preset terminal uplink frequency resource;
the positioning module is used for acquiring the real-time position of the terminal;
the sending time lead acquisition module calculates the sending time lead by using the distance between the terminal and the target satellite;
the frequency offset compensation quantity acquisition module is used for calculating frequency offset compensation quantity according to the ephemeris;
the terminal sending module is used for encrypting data fields in the information of the Internet of things by using an application layer key and carrying out integrity protection on the whole information of the Internet of things by using a preset network layer key, wherein the information of the Internet of things comprises terminal identifications corresponding to the terminals one by one; and performing frequency offset compensation on the information added with the terminal identification based on the frequency offset compensation amount, and transmitting and uploading the information after frequency offset compensation to a satellite according to the transmission time advance.
9. A satellite for the Internet of things of low earth orbit satellites is characterized in that when the satellite is not connected with a ground station, the satellite stores and forwards Internet of things information uploaded by a terminal based on a store-and-forward mode;
the satellite includes:
the terminal information receiving module is used for receiving the Internet of things information uploaded by the terminal;
the storage module is used for storing the Internet of things information uploaded by the terminal during the period that the satellite is not connected with the ground station;
and the satellite sending module is used for forwarding the information of the Internet of things stored in the storage module to a network side through the ground station when the satellite and the ground station are changed from the unconnected state to the connected state.
10. A low earth orbit satellite Internet of things system is characterized by comprising a terminal, at least one satellite, a ground station and network side equipment, wherein when the satellite is not connected with the ground station, the terminal, the satellite, the ground station and the network side equipment adopt a store-and-forward mode to transmit Internet of things information;
the network side equipment comprises a network server, an application server and a user data server, the network server performs repeated data filtering processing on received Internet of things information, a network layer key is obtained according to a terminal identifier in the information after the repeated data filtering processing, integrity verification is performed on the information after the repeated data filtering processing through the network layer key, after the integrity verification is passed, a data field in the information after the repeated data filtering processing is forwarded to the application server, the application server obtains the application layer key from the user data server, and the data field in the Internet of things information is decrypted through the application layer key.
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