CN113115429A

CN113115429A - Crystal oscillator frequency offset determination method, device and communication system

Info

Publication number: CN113115429A
Application number: CN202110245853.1A
Authority: CN
Inventors: 李立华; 周文慧
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-07-13
Anticipated expiration: 2041-03-05
Also published as: CN113115429B

Abstract

The embodiment of the invention provides a method, a device and a communication system for determining a crystal oscillator frequency offset. The terminal calculates the carrier frequency offset of the synchronous signal block based on the first synchronous sequence, the second synchronous sequence and a frequency offset estimation calculation method; carrying out frequency offset pre-compensation on the transmitting frequency based on the carrier frequency offset to obtain a first transmitting frequency; and transmitting the carrier frequency offset to the satellite according to the first transmission frequency. The satellite calculates the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite; and transmitting the crystal oscillator frequency offset to the gateway station. And the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite. The satellite forwards the random access response signal to the terminal. And the terminal acquires the crystal oscillator frequency offset carried by the random access response signal. Based on the processing, the crystal oscillator frequency deviation can be determined without a temperature sensor, and then the terminal can perform frequency deviation pre-compensation based on the crystal oscillator frequency deviation, so that the accuracy of the frequency deviation pre-compensation of the terminal can be improved.

Description

Crystal oscillator frequency offset determination method, device and communication system

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method, an apparatus, and a communication system for determining a crystal oscillation frequency offset.

Background

In a satellite communication system, due to the high-speed movement of a satellite, a doppler frequency offset is generated in a signal transmitted from the satellite to a terminal. In addition, the carrier waves generated when the terminal transmits and receives signals are generated by a crystal oscillator inside the terminal. Due to the influence of factors such as environment temperature, voltage and noise, a frequency deviation exists between the actual frequency of the carrier generated by the crystal oscillator and the preset nominal frequency, and the frequency deviation is the crystal oscillator frequency deviation of the terminal.

In the prior art, a technician may measure actual frequencies of carriers generated by a crystal oscillator at different environmental temperatures, then calculate frequency offsets of the crystal oscillator at different environmental temperatures according to preset nominal frequencies, and record a corresponding relationship between the environmental temperatures and the frequency offsets of the crystal oscillator in a terminal. Correspondingly, before the terminal sends the signal to the satellite, the current environment temperature can be determined through the temperature sensor, and the crystal oscillator frequency offset corresponding to the current environment temperature is determined in the corresponding relation. Furthermore, the terminal can perform frequency offset pre-compensation based on the determined crystal oscillator frequency offset and the Doppler frequency offset of the received signal.

However, when the crystal oscillator frequency offsets at different environmental temperatures are measured, the number of the set environmental temperatures is limited, that is, the corresponding relationship between the environmental temperature recorded in the terminal and the crystal oscillator frequency offsets is limited, and if the current environmental temperature does not exist in the corresponding relationship, the corresponding crystal oscillator frequency offsets cannot be determined. In addition, if the terminal is not configured with a temperature sensor, the current environment temperature cannot be determined, and the crystal oscillator frequency offset corresponding to the current environment temperature cannot be determined. At this time, the terminal can only perform frequency offset pre-compensation based on the doppler frequency offset of the received signal, resulting in lower accuracy of the frequency offset pre-compensation of the terminal.

Disclosure of Invention

The embodiment of the invention aims to provide a method, a device and a communication network for determining the frequency offset of a crystal oscillator so as to improve the accuracy of the frequency offset precompensation of a terminal. The specific technical scheme is as follows:

in a first aspect, to achieve the above object, an embodiment of the present invention provides a communication system, including: a terminal, a satellite and a gateway station, wherein:

the satellite is used for sending a synchronization signal block carrying a first synchronization sequence to the terminal;

the terminal is used for calculating the carrier frequency offset of the synchronous signal block based on the first synchronous sequence, a locally stored second synchronous sequence and a frequency offset estimation calculation method when the synchronous signal block is received; based on the carrier frequency offset, carrying out frequency offset precompensation on the transmitting frequency when the terminal transmits a signal to obtain a first transmitting frequency; sending the carrier frequency offset to the satellite according to the first transmitting frequency;

the satellite is further used for calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite when the carrier frequency offset is received; and sending the crystal oscillator frequency offset to the gateway station;

the gateway station is used for sending a random access response signal carrying the crystal oscillator frequency offset to the satellite when receiving the crystal oscillator frequency offset;

the satellite is further used for sending the random access response signal to the terminal when the random access response signal is received;

and the terminal is further configured to obtain the crystal oscillator frequency offset carried by the random access response signal when receiving the random access response signal.

In a second aspect, to achieve the above object, an embodiment of the present invention provides a crystal oscillator frequency offset determining method, where the method is applied to a satellite in a communication system, and the communication system further includes: a terminal and a gateway station, the method comprising:

sending a synchronization signal block carrying a first synchronization sequence to the terminal, so that when the terminal receives the synchronization signal block, based on the first synchronization sequence, a second synchronization sequence locally stored in the terminal and a frequency offset estimation calculation method, a carrier frequency offset of the synchronization signal block is calculated, and based on the carrier frequency offset, frequency offset pre-compensation is performed on a transmitting frequency when the terminal sends a signal, so as to obtain a first transmitting frequency; sending the carrier frequency offset to the satellite according to the first transmitting frequency;

when the carrier frequency offset is received, calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite when the carrier frequency offset is received;

sending the crystal oscillator frequency offset to the gateway station so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite;

and when receiving the random access response signal, sending the random access response signal to the terminal so that the terminal obtains the crystal oscillator frequency offset carried by the random access response signal.

In a third aspect, to achieve the above object, an embodiment of the present invention provides a method for determining a crystal frequency offset, where the method is applied to a terminal in a communication system, and the communication system further includes: a satellite and a gateway station, the method comprising:

when a synchronization signal block which is sent by the satellite and carries a first synchronization sequence is received, calculating the carrier frequency offset of the synchronization signal block based on the first synchronization sequence, a second synchronization sequence which is locally stored and a frequency offset estimation calculation method;

performing frequency offset pre-compensation on the transmitting frequency when the signal is transmitted based on the carrier frequency offset to obtain a first transmitting frequency;

according to the first transmitting frequency, sending the carrier frequency offset to the satellite, so that the satellite calculates the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency when the satellite receives the carrier frequency offset, and sends the crystal oscillator frequency offset to the gateway station, so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite, and the satellite sends the random access response signal to the terminal;

and when the random access response signal is received, acquiring the crystal oscillator frequency offset carried by the random access response signal.

In a fourth aspect, to achieve the above object, an embodiment of the present invention provides a crystal oscillator frequency offset determining method, where the method is applied to a gateway station in a communication system, and the communication system further includes: a satellite and a terminal, the method comprising:

receiving a crystal oscillator frequency offset sent by the satellite; the crystal oscillator frequency offset is calculated based on the carrier frequency offset and the receiving frequency of the satellite when the satellite receives the carrier frequency offset sent by the terminal; the carrier frequency offset is calculated by the terminal based on the first synchronization sequence, a second synchronization sequence locally stored by the terminal and a frequency offset estimation algorithm after the terminal receives a synchronization signal block which is sent by the satellite and carries the first synchronization sequence;

and sending a random access response signal carrying the crystal oscillator frequency offset to the satellite so that the satellite forwards the random access response signal to the terminal, and the terminal acquires the crystal oscillator frequency offset carried by the random access response signal.

In a fifth aspect, in order to achieve the above object, an embodiment of the present invention provides a crystal frequency offset determining apparatus, where the apparatus is applied to a satellite in a communication system, and the communication system further includes: a terminal and a gateway station, the apparatus comprising:

a first sending module, configured to send a synchronization signal block carrying a first synchronization sequence to the terminal, so that when the terminal receives the synchronization signal block, a carrier frequency offset of the synchronization signal block is calculated based on the first synchronization sequence, a second synchronization sequence locally stored in the terminal, and a frequency offset estimation calculation method, and frequency offset pre-compensation is performed on a transmission frequency when the terminal sends a signal based on the carrier frequency offset, so as to obtain a first transmission frequency; sending the carrier frequency offset to the satellite according to the first transmitting frequency;

the determining module is used for calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite when receiving the carrier frequency offset;

a second sending module, configured to send the crystal oscillator frequency offset to the gateway station, so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite;

and a third sending module, configured to send the random access response signal to the terminal when receiving the random access response signal, so that the terminal obtains the crystal oscillator frequency offset carried by the random access response signal.

In a sixth aspect, to achieve the above object, an embodiment of the present invention provides a crystal oscillator frequency offset determining apparatus, where the apparatus is applied to a terminal in a communication system, and the communication system further includes: a satellite and a gateway station, the apparatus comprising:

the first determining module is used for calculating the carrier frequency offset of a synchronization signal block based on a first synchronization sequence, a second synchronization sequence stored locally and a frequency offset estimation calculation method when the synchronization signal block which is sent by the satellite and carries the first synchronization sequence is received;

the second determining module is used for carrying out frequency offset precompensation on the transmitting frequency during signal transmission based on the carrier frequency offset to obtain a first transmitting frequency;

a sending module, configured to send the carrier frequency offset to the satellite according to the first transmitting frequency, so that the satellite calculates a crystal oscillator frequency offset of the terminal based on the carrier frequency offset and a receiving frequency when the satellite receives the carrier frequency offset, and sends the crystal oscillator frequency offset to the gateway station, so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite, so that the satellite sends the random access response signal to the terminal;

and the acquisition module is used for acquiring the crystal oscillator frequency offset carried by the random access response signal when the random access response signal is received.

In a seventh aspect, in order to achieve the above object, an embodiment of the present invention provides a crystal oscillator frequency offset determining apparatus, where the apparatus is applied to a gateway station in a communication system, and the communication system further includes: a satellite and a terminal, the apparatus comprising:

the receiving module is used for receiving the crystal oscillator frequency offset sent by the satellite; the crystal oscillator frequency offset is calculated based on the carrier frequency offset and the receiving frequency of the satellite when the satellite receives the carrier frequency offset sent by the terminal; the carrier frequency offset is calculated by the terminal based on the first synchronization sequence, a second synchronization sequence locally stored by the terminal and a frequency offset estimation algorithm after the terminal receives a synchronization signal block which is sent by the satellite and carries the first synchronization sequence;

a sending module, configured to send a random access response signal carrying the crystal oscillator frequency offset to the satellite, so that the satellite forwards the random access response signal to the terminal, and the terminal obtains the crystal oscillator frequency offset carried by the random access response signal.

The embodiment of the invention also provides electronic equipment which comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete mutual communication through the communication bus; a memory for storing a computer program; a processor, configured to implement the steps of the crystal oscillator frequency offset determination method according to any one of the second aspect, the third aspect, or the fourth aspect when executing the program stored in the memory.

An embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored, and the computer program, when executed by a processor, implements the crystal oscillator frequency offset determination method steps of any one of the second aspect, the third aspect, or the fourth aspect.

An embodiment of the present invention further provides a computer program product containing instructions, which when run on a computer, causes the computer to execute the crystal frequency offset determination method according to any one of the second aspect, the third aspect, or the fourth aspect.

According to the technical scheme provided by the embodiment of the invention, a satellite sends a synchronous signal block to a terminal; the first synchronization sequence is carried in the synchronization signal block. When the terminal receives the synchronous signal block, calculating the carrier frequency offset of the synchronous signal block based on the first synchronous sequence, the second synchronous sequence stored locally and a frequency offset estimation calculation method; based on carrier frequency offset, carrying out frequency offset precompensation on the transmitting frequency when the terminal transmits a signal to obtain a first transmitting frequency; and transmitting the carrier frequency offset to the satellite according to the first transmitting frequency. When the satellite receives the carrier frequency offset, calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite when receiving the carrier frequency offset; and sends the crystal oscillator frequency offset to the gateway station. And when receiving the crystal oscillator frequency offset, the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite. The satellite forwards the random access response signal to the terminal when receiving the random access response signal. And when receiving the random access response signal, the terminal acquires the crystal oscillator frequency offset carried by the random access response signal.

Based on the processing, the crystal oscillator frequency offset of the terminal can be determined without a temperature sensor, and subsequently, the terminal can perform frequency offset pre-compensation based on the determined crystal oscillator frequency offset. Furthermore, the accuracy of the frequency offset precompensation of the terminal can be improved.

Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other embodiments can be obtained by using the drawings without creative efforts.

Fig. 1 is a block diagram of a communication system according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for determining a frequency offset of a crystal oscillator according to an embodiment of the present invention;

fig. 3 is a flowchart of another method for determining a frequency offset of a crystal oscillator according to an embodiment of the present invention;

fig. 4 is a flowchart of another method for determining a frequency offset of a crystal oscillator according to an embodiment of the present invention;

fig. 5 is a flowchart of another method for determining a frequency offset of a crystal oscillator according to an embodiment of the present invention;

fig. 6 is a flowchart of another method for determining a frequency offset of a crystal oscillator according to an embodiment of the present invention;

fig. 7 is a flowchart of a method for establishing a communication connection between a gateway station and a terminal according to an embodiment of the present invention;

FIG. 8 is a comparison of an RMSE provided in accordance with an embodiment of the present invention;

FIG. 9 is a diagram illustrating a comparison of crystal oscillator accuracies according to an embodiment of the present invention

FIG. 10 is a comparison of another RMSE provided in accordance with an embodiment of the present invention;

FIG. 11 is a comparison graph of the crystal oscillator precision provided by an embodiment of the present invention;

fig. 12 is a structural diagram of an apparatus for determining a crystal frequency offset according to an embodiment of the present invention;

fig. 13 is a block diagram of another apparatus for determining crystal frequency offset according to an embodiment of the present invention;

fig. 14 is a block diagram of another apparatus for determining crystal frequency offset according to an embodiment of the present invention;

fig. 15 is a structural diagram of an electronic device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived from the embodiments given herein by one of ordinary skill in the art, are within the scope of the invention.

Referring to fig. 1, fig. 1 is a block diagram of a communication system according to an embodiment of the present invention, where the communication system includes: terminals, satellites and gateway stations. Wherein:

the satellite may transmit a synchronization signal block carrying the first synchronization sequence to the terminal.

The terminal can calculate the carrier frequency offset of the synchronous signal block based on the first synchronous sequence, the second synchronous sequence stored locally and a frequency offset estimation calculation method when receiving the synchronous signal block; based on carrier frequency offset, carrying out frequency offset precompensation on the transmitting frequency when the terminal transmits a signal to obtain a first transmitting frequency; and transmitting the carrier frequency offset to the satellite according to the first transmission frequency.

The satellite can calculate the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite when receiving the carrier frequency offset; and sends the crystal oscillator frequency offset to the gateway station.

The gateway station may send a random access response signal carrying the crystal oscillator frequency offset to the satellite when receiving the crystal oscillator frequency offset.

The satellite may also transmit a random access response signal to the terminal upon receiving the random access response signal.

The terminal may obtain the crystal oscillator frequency offset carried by the random access response signal when receiving the random access response signal.

Based on the communication system provided by the embodiment of the invention, the crystal oscillator frequency offset of the terminal can be determined without a temperature sensor, and subsequently, the terminal can perform frequency offset pre-compensation based on the determined crystal oscillator frequency offset. Furthermore, the accuracy of the frequency offset precompensation of the terminal can be improved.

For further embodiments of the above-described communication system, reference may be made to the following description of method embodiments relating to terminals, satellites and gateway stations.

Referring to fig. 2, fig. 2 is a flowchart of a method for determining a crystal frequency offset according to an embodiment of the present invention, where the method is applicable to a satellite in the communication system, and the communication system further includes: a terminal and a gateway station. The method may comprise the steps of:

s201: sending a synchronous signal block carrying a first synchronous sequence to a terminal, so that when the terminal receives the synchronous signal block, calculating the carrier frequency offset of the synchronous signal block based on the first synchronous sequence, a second synchronous sequence locally stored in the terminal and a frequency offset estimation calculation method, and performing frequency offset pre-compensation on the transmitting frequency when the terminal sends a signal based on the carrier frequency offset to obtain a first transmitting frequency; and transmitting the carrier frequency offset to the satellite according to the first transmitting frequency.

S202: and when the carrier frequency offset is received, calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite receiving the carrier frequency offset.

S203: and sending the crystal oscillator frequency deviation to the gateway station so that the gateway station sends a random access response signal carrying the crystal oscillator frequency deviation to the satellite.

S204: and when receiving the random access response signal, sending the random access response signal to the terminal so that the terminal acquires the crystal oscillator frequency offset carried in the random access response signal.

Based on the method for determining the crystal oscillator frequency offset provided by the embodiment of the invention, the crystal oscillator frequency offset of the terminal can be determined without a temperature sensor, and subsequently, the terminal can perform frequency offset pre-compensation based on the determined crystal oscillator frequency offset. Furthermore, the accuracy of the frequency offset precompensation of the terminal can be improved.

In step S201, in one implementation, in the satellite communication system, before the terminal and the gateway station perform data transmission, a communication connection needs to be established through a satellite. When the preset period is reached, the gateway station may transmit SSBs (Synchronization Signal and PBCH Block) to the satellite. Further, the satellite may forward the received synchronization signal block to the terminal.

Correspondingly, when receiving the synchronization signal block, the terminal may calculate the carrier frequency offset of the synchronization signal block, and then send the calculated carrier frequency offset to the satellite. The specific processing manner of the terminal can be referred to in the related description of the following embodiments.

In addition, when the terminal and the gateway station establish a communication connection, after receiving the synchronization signal block, the terminal may further send a random access request signal carrying a Preamble (Preamble) to the satellite, so that the satellite sends the random access request signal carrying the Preamble to the gateway station.

In one implementation, when receiving the synchronization signal block, the terminal may send a random access request signal carrying a preamble and a carrier frequency offset to the satellite. Wherein the preamble is used to indicate a type of a random access request signal of the terminal. The number of the preambles is 64, the 0 th to 53 th preambles represent contention based random access request signals, and the 54 th to 63 th preambles represent non-contention based random access request signals.

In step S202, when receiving the carrier frequency offset sent by the terminal, the satellite may calculate the crystal frequency offset of the terminal based on the carrier frequency offset and the receiving frequency when the satellite receives the carrier frequency offset. It is understood that the terminal transmits a random access request signal carrying a preamble and a carrier frequency offset to the satellite. The receiving frequency of the satellite receiving the carrier frequency offset, that is, the receiving frequency of the satellite receiving the random access request signal.

In one embodiment of the present invention, step S202 may include the steps of: and calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset, the receiving frequency when the satellite receives the carrier frequency offset and a first preset formula.

Wherein, the first preset formula is as follows:

F₁indicating the frequency deviation of the crystal oscillator, F₂Representing carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Indicating the nominal frequency, f, at which the terminal receives the signal₃Which represents the receiving frequency at which the satellite receives the carrier frequency offset.

In one implementation, the receiving frequency when the satellite receives the carrier frequency offset may be represented by the following formula (2):

f₃＝(f₁-F₁+A)(1+D₂) (2)

f₃representing the receiving frequency, f, of the satellite receiving the carrier frequency offset₁Indicating the nominal frequency, F, at which the terminal transmits the signal₁Representing the frequency deviation of the crystal oscillator, A representing the first frequency compensation value when the terminal sends signals, D₂Which represents the relative doppler frequency offset of the random access request signal transmitted by the terminal.

Since the time from the transmission of the synchronization signal block from the satellite to the terminal to the reception of the random access request signal by the satellite is short, the variation in relative doppler frequency offset in a short time is small. Therefore, it can be considered that the relative doppler shift is not changed in a short time, and the relative doppler shift of the random access request signal transmitted by the terminal is the same as the relative doppler shift of the synchronization signal block received by the terminal. Further, the following formula (3) can be obtained:

D₂indicating the relative Doppler shift, D, of the random access request signal transmitted by the terminal₁The method comprises the steps of representing the relative Doppler frequency offset of a synchronous signal block received by a terminal, v representing the moving speed of a satellite relative to the terminal, c representing the speed of light, and alpha representing the included angle between the incident direction of the signal received by the terminal and the moving direction of the terminal.

Because the terminal has crystal frequency offset, the carrier frequency offset of the synchronization signal block received by the terminal can be expressed as the following formula (4):

F₂＝f₂D₁+F₁ (4)

F₂indicating the carrier frequency offset, f, of the block of synchronization signals received by the terminal₂Indicating the nominal frequency, D, at which the terminal receives the signal₁Indicating the relative Doppler shift, F, of the block of synchronization signals received by the terminal₁Indicating crystal frequency deviation.

Based on the above formula (2), formula (3), and formula (4), the following formula (5) can be obtained:

f₃representing the receiving frequency, F, of the satellite at the time of receiving the carrier frequency offset₁Indicating the frequency deviation of the crystal oscillator, F₂Representing carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Representing the nominal frequency at which the terminal receives the signal.

The crystal oscillator frequency offset calculation method shown in the formula (1) can be obtained based on the formula (5).

For step S203 and step S204, after the crystal frequency offset of the terminal is obtained through calculation, the satellite may send a random access request signal carrying a preamble and the crystal frequency offset to the gateway station. Correspondingly, after receiving the random access request signal, the gateway station may send a random access response signal carrying the crystal oscillator frequency offset to the satellite. Further, the satellite may forward the random access response signal to the terminal.

Correspondingly, after receiving the random access response signal, the terminal may obtain the crystal oscillator frequency offset carried by the random access response signal. Subsequently, before the terminal sends the signal to the satellite, the terminal may perform frequency offset pre-compensation based on the crystal frequency offset.

Referring to fig. 3, fig. 3 is a flowchart of another method for determining a crystal oscillator frequency offset according to an embodiment of the present invention, where the method may be applied to a terminal in the communication system, where the communication system further includes: satellites and gateway stations. The method may comprise the steps of:

s301: when a synchronization signal block which is sent by a satellite and carries a first synchronization sequence is received, the carrier frequency offset of the synchronization signal block is calculated based on the first synchronization sequence, a second synchronization sequence which is locally stored and a frequency offset estimation calculation method.

S302: and carrying out frequency offset pre-compensation on the transmitting frequency when the signal is transmitted based on the carrier frequency offset to obtain a first transmitting frequency.

S303: and sending the carrier frequency offset to the satellite according to the first transmitting frequency so that the satellite calculates the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency when the satellite receives the carrier frequency offset, and sending the crystal oscillator frequency offset to the gateway station so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite so that the satellite sends the random access response signal to the terminal.

S304: and when the random access response signal is received, acquiring the crystal oscillator frequency offset carried by the random access response signal.

In step S301, in one implementation, in the satellite communication system, before the terminal and the gateway station perform data transmission, a communication connection needs to be established through the satellite. Upon reaching the preset period, the gateway station may transmit a synchronization signal block to the satellite. Further, the satellite may forward the received synchronization signal block to the terminal.

The Synchronization Signal block carries PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal). The primary synchronization sequence and the secondary synchronization sequence are the first synchronization sequence in the embodiment of the present invention.

Accordingly, when receiving the synchronization signal block, the terminal may extract the first synchronization sequence carried in the synchronization signal block. When the gateway station sends the synchronous signal block, the first synchronous sequence carried in the synchronous signal block is the same as the second synchronous sequence stored locally in the terminal. Therefore, the terminal can calculate the carrier frequency offset of the synchronization signal block based on the first synchronization sequence, the second synchronization sequence and the frequency offset estimation method. The carrier frequency offset of the synchronization signal block may represent an offset of the frequency of the synchronization signal block in the frequency domain. The frequency offset estimation algorithm may be a maximum likelihood estimation algorithm.

In one embodiment of the present invention, referring to fig. 4, step S302 may include the steps of:

s3021: and calculating a first frequency compensation value when the terminal sends the signal based on the carrier frequency offset, the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a second preset formula.

Wherein the second predetermined formula is:

a represents a first frequency compensation value, F₂Representing carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Representing the nominal frequency at which the terminal receives the signal.

S3022: and calculating the sum of the first frequency compensation value and the nominal frequency when the terminal sends the signal as the first transmitting frequency.

For steps S3021 and S3022, the nominal frequency at which the terminal receives the signal may be expressed as the following equation (7):

f₁＝(f₁+A)(1+D₂) (7)

f₁representing the nominal frequency at which the terminal transmits the signal, a representing the first frequency offset, D₂Which represents the relative doppler frequency offset of the random access request signal transmitted by the terminal.

Further, based on the above equations (3), (4) and (7), the calculation method of the first frequency compensation value shown in the above equation (6) can be obtained.

For step S303 and step S304, after the first transmission frequency is obtained through calculation, the terminal transmits the carrier frequency offset to the satellite at the first transmission frequency.

In addition, when the terminal and the gateway station establish communication connection, after receiving the synchronization signal block, the terminal may further send a random access request signal carrying a preamble to the satellite, so that the satellite sends the random access request signal carrying the preamble to the gateway station. In one implementation, when receiving the synchronization signal block, the terminal may send a random access request signal carrying a preamble and a carrier frequency offset to the satellite.

Correspondingly, after receiving the random access request signal carrying the preamble and the carrier frequency offset, the satellite may calculate the crystal oscillator frequency offset of the terminal based on the carrier frequency offset and the receiving frequency of the satellite when receiving the carrier frequency offset. The specific processing manner of the satellite can be referred to the related description of the foregoing embodiments. Further, the satellite may transmit a random access request signal to the gateway station.

After receiving the random access request signal, the gateway station may send a random access response signal (i.e., Msg2) carrying a crystal frequency offset to the satellite. Further, the satellite may transmit a random access response signal to the terminal.

Correspondingly, after receiving the random access response signal, the terminal may extract the crystal frequency offset carried by the random access response signal. Subsequently, before the terminal sends the signal to the satellite, the terminal may perform frequency offset pre-compensation based on the crystal frequency offset.

In one embodiment of the present invention, referring to fig. 5, after step S304, the method may further include the steps of:

s305: and if the frequency deviation of the crystal oscillator is 0, calculating a second frequency compensation value when the terminal sends the signal based on the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a third preset formula.

Wherein, the third preset formula is:

b represents a second frequency compensation value, F₂Representing carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Indicating the nominal frequency, D, at which the terminal receives the signal₁Representing the relative doppler shift of the synchronization signal block.

S306: and if the crystal oscillator frequency offset is not 0, calculating a second frequency compensation value when the terminal sends the signal based on the crystal oscillator frequency offset, the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a fourth preset formula.

Wherein, the fourth preset formula is:

b represents a second frequency compensation value, F₂Representing carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Indicating the nominal frequency, D, at which the terminal receives the signal₁Representing the relative doppler frequency offset of the synchronization signal block; f₁Indicating crystal frequency deviation.

S307: and calculating the sum of the second frequency compensation value and the nominal frequency when the terminal sends the signal as a second transmitting frequency.

S308: and communicating with the satellite according to the second transmission frequency.

For step S305 and step S306, if the crystal frequency offset is 0, it indicates that there is no crystal frequency offset in the terminal. The terminal may calculate the second frequency compensation value when the terminal transmits the signal based on the above equation (8). And if the frequency deviation of the crystal oscillator is not 0, indicating that the terminal has the frequency deviation of the crystal oscillator. The terminal may calculate the second frequency compensation value when the terminal transmits the signal based on the above equation (9).

For step S307 and step S308, the terminal may calculate a sum of the second frequency compensation value and a nominal frequency when the terminal transmits a signal, so as to obtain a second transmission frequency. The terminal then communicates with the satellite based on transmitting at a second transmit frequency.

For example, when the terminal establishes a communication connection with the gateway station, after receiving the random access response signal, the terminal may send Msg3 to the satellite, where Msg3 carries an RRC (Radio Resource Control) request, so that the satellite sends Msg3 to the gateway station.

In one implementation, the terminal may transmit Msg3 to the satellite at the second transmit frequency.

Referring to fig. 6, fig. 6 is a flowchart of another method for determining a crystal oscillator frequency offset according to an embodiment of the present invention, where the method is applied to a gateway station in the communication system, and the communication system further includes: a terminal and a satellite. The method may comprise the steps of:

s601: and receiving the crystal oscillator frequency offset sent by the satellite.

The crystal oscillator frequency offset is obtained by calculation based on the carrier frequency offset and the receiving frequency when the satellite receives the carrier frequency offset sent by the terminal after the satellite receives the carrier frequency offset; the carrier frequency offset is calculated by the terminal based on the first synchronization sequence, a second synchronization sequence locally stored by the terminal and a frequency offset estimation calculation method after the terminal receives a synchronization signal block which is sent by a satellite and carries the first synchronization sequence.

S602: and sending a random access response signal carrying the crystal oscillator frequency offset to the satellite so that the satellite forwards the random access response signal to the terminal, and the terminal acquires the crystal oscillator frequency offset carried by the random access response signal.

For step S601 and step S602, in one implementation, before data transmission between the terminal and the gateway station in the satellite communication system, a communication connection needs to be established through a satellite. Upon reaching the preset period, the gateway station may transmit a synchronization signal block to the satellite. Further, the satellite may forward the received synchronization signal block to the terminal. When receiving the synchronization signal block, the terminal may calculate a carrier frequency offset of the synchronization signal block, and then the terminal may send a random access request signal carrying a preamble and the carrier frequency offset to the satellite.

Correspondingly, the gateway station may receive a random access request signal carrying a preamble and a carrier frequency offset sent by the satellite, and send a random access response signal carrying a crystal oscillator frequency offset to the satellite. Further, the satellite may forward the random access response signal to the terminal. Correspondingly, the terminal obtains the crystal oscillator frequency offset carried by the random access response signal. The specific processing manner of the satellite and the terminal can be referred to the related description of the foregoing embodiments.

Referring to fig. 7, fig. 7 is a flowchart of a method for a gateway station to establish a communication connection with a terminal according to an embodiment of the present invention. The method may comprise the steps of:

s701: and when the gateway station reaches a preset period, sending a synchronization signal block carrying the first synchronization sequence to the satellite.

S702: the satellite, upon receiving the synchronization signal block, transmits the synchronization signal block to the terminal.

S703: when the terminal receives a synchronization signal block sent by a satellite, the carrier frequency offset of the synchronization signal block is calculated based on the first synchronization sequence, the second synchronization sequence stored locally and a frequency offset estimation method.

S704: the terminal carries out frequency offset pre-compensation on the transmitting frequency when the signal is transmitted based on the carrier frequency offset to obtain a first transmitting frequency.

S705: and the terminal sends a random access request signal carrying a lead code and carrier frequency offset to the satellite according to the first transmitting frequency.

S706: when the satellite receives the random access request signal carrying the lead code and the carrier frequency offset, the crystal oscillator frequency offset of the terminal is calculated based on the carrier frequency offset and the receiving frequency of the satellite when the random access request signal is received.

S707: and the satellite sends a random access request signal carrying the lead code and the crystal oscillator frequency offset to the gateway station.

S708: and the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite when receiving the random access request signal carrying the lead code and the crystal oscillator frequency offset sent by the satellite.

S709: the satellite transmits a random access response signal to the terminal when receiving the random access response signal.

S7010: and when receiving the random access response signal, the terminal acquires the crystal oscillator frequency offset carried by the random access response signal.

S7011: and the terminal performs frequency offset precompensation on the transmitting frequency when the signal is transmitted based on the crystal oscillator frequency offset to obtain a second transmitting frequency.

S7012: the terminal sends Msg3 to the satellite according to the second transmit frequency.

S7013: the satellite, upon receiving Msg3, sends Msg3 to the gateway station.

S7014: the gateway station sends a contention resolution message to the satellite upon receiving the Msg 3.

S7015: the satellite, upon receiving the contention resolution message, transmits the contention resolution message to the terminal.

For steps S701 and S702, in the satellite communication system, before the terminal performs data transmission with the gateway station, the gateway station may periodically transmit a synchronization signal block to the satellite.

For step S703, step S704, and step S705, the terminal may determine a carrier frequency offset of the received synchronization signal block, and perform frequency offset pre-compensation based on the determined carrier frequency offset to obtain a first transmission frequency. Further, the terminal may send a random access request signal carrying a preamble and a carrier frequency offset to the satellite according to the first transmission frequency.

For steps S706 and S707, after the satellite receives the random access request signal, the crystal frequency offset of the terminal may be determined based on the carrier frequency offset. Further, the satellite may send a random access request signal carrying a preamble and a crystal frequency offset to the gateway station.

For steps S708, S709, and S7010, after the gateway station receives the random access request signal carrying the preamble and the crystal frequency offset, the gateway station may send a random access response signal (i.e., Msg2) carrying the crystal frequency offset to the satellite. The satellite may forward the received random access response signal to the terminal. Further, the terminal may obtain the crystal frequency offset carried in the received random access response signal.

For step S7011, step S7012, step S7013, step S7014, and step S7015, the terminal may perform frequency offset pre-compensation on the transmission frequency when sending the signal based on the crystal frequency offset to obtain a second transmission frequency. Further, the terminal may send Msg3 carrying the RRC request to the satellite at the second transmit frequency. The satellite, upon receiving Msg3, may forward the received Msg3 to the gateway station. The gateway station, upon receiving Msg3, may send a contention resolution message (i.e., Msg4) to the satellite. Further, the satellite may forward a contention resolution message to the terminal. The terminal may determine that the establishment of the communication connection with the gateway station is completed after receiving the contention resolution message.

Therefore, the method for determining the crystal oscillator frequency offset provided by the embodiment of the invention can determine the crystal oscillator frequency offset of the terminal in the process of establishing communication connection between the terminal and the gateway station. Subsequently, when the terminal performs data transmission with the gateway station, the frequency offset pre-compensation can be performed based on the crystal oscillator frequency offset, so that the effectiveness of the frequency offset pre-compensation can be improved.

Referring to fig. 8, fig. 8 is a graph comparing RMSE (Root Mean square Error) provided by an embodiment of the present invention.

In fig. 8, a broken line with a triangle indicates the RMSE of the crystal frequency deviation (which may be referred to as a first crystal frequency deviation) determined based on the prior art, as a corresponding relationship with temperature. When the line with the diamond shape indicates that a channel through which the terminal sends a signal to the satellite is a rice channel, the corresponding relationship between the RMSE of the crystal oscillator frequency offset (which may be referred to as a second crystal oscillator frequency offset) and the temperature is calculated based on the crystal oscillator frequency offset determination method provided by the embodiment of the present invention. When the straight line with the dots indicates that a channel through which a terminal sends a signal to a satellite is an AWG (gaussian) channel, the corresponding relationship between the RMSE of the crystal frequency offset (which may be referred to as a third crystal frequency offset) and the temperature is calculated based on the crystal frequency offset determination method provided by the embodiment of the present invention.

It can be seen that, under the same temperature, the RMSE of the second crystal oscillator frequency offset and the RMSE of the third crystal oscillator frequency offset are both smaller than the RMSE of the first crystal oscillator frequency offset. That is to say, based on the method for determining the crystal oscillator frequency offset provided by the embodiment of the present invention, the accuracy of the calculated crystal oscillator frequency offset is higher.

In addition, the RMSE of the second crystal oscillator frequency offset and the RMSE of the third crystal oscillator frequency offset do not change with temperature changes, that is, based on the crystal oscillator frequency offset determination method provided by the embodiment of the present invention, the accuracy of the calculated crystal oscillator frequency offset is stable, and does not change with temperature changes. The RMSE of the first crystal oscillator frequency offset changes with temperature changes, that is, the accuracy of the crystal oscillator frequency offset determined based on the prior art is unstable and may change with temperature changes.

Referring to fig. 9, fig. 9 is a diagram illustrating a comparison of crystal oscillator accuracies according to an embodiment of the present invention. The terminal crystal oscillator precision refers to the precision of the frequency of the carrier wave generated by the crystal oscillator of the terminal. The smaller the crystal oscillator precision, the better the crystal oscillator performance.

In fig. 9, a broken line with a five-pointed star indicates a correspondence relationship between the accuracy of the terminal crystal oscillator without the frequency offset precompensation and the temperature, in addition to fig. 8. And the broken line with the triangle represents the corresponding relation between the precision and the temperature of the terminal crystal oscillator after the frequency offset pre-compensation is carried out on the basis of the first crystal oscillator frequency offset. And the straight line with the rhombus represents the corresponding relation between the terminal crystal oscillator precision and the temperature after the frequency offset pre-compensation is carried out on the basis of the second crystal oscillator frequency offset. And the straight line with the round points represents the corresponding relation between the terminal crystal oscillator precision and the temperature after the frequency offset pre-compensation is carried out on the basis of the third crystal oscillator frequency offset.

Therefore, under the condition of the same temperature, the precision of the terminal crystal oscillator after the frequency offset pre-compensation is performed based on the second crystal oscillator frequency offset and the third crystal oscillator frequency offset is smaller than that of the terminal crystal oscillator after the frequency offset pre-compensation is performed based on the first crystal oscillator frequency offset.

In addition, the terminal crystal oscillator subjected to frequency offset pre-compensation based on the second crystal oscillator frequency offset and the third crystal oscillator frequency offset is stable in precision and cannot change along with temperature change. The terminal crystal oscillator precision after frequency offset pre-compensation is carried out based on the first crystal oscillator frequency offset is unstable and can change along with temperature change.

Referring to fig. 10, fig. 10 is a comparison graph of another RMSE provided in accordance with an embodiment of the present invention. The abscissa signal-to-noise ratio in fig. 10 is the signal-to-noise ratio of the channel over which the terminal transmits signals to the satellite.

On the basis of fig. 8, in fig. 10, a line with a triangle indicates a correspondence relationship between RMSE and SNR (signal-to-noise ratio) of the first crystal frequency offset. And the broken line with the diamond represents the corresponding relation between the RMSE of the second crystal oscillator frequency deviation and the signal-to-noise ratio. The broken line with dots represents the corresponding relation between the RMSE of the third crystal oscillator frequency deviation and the signal-to-noise ratio.

It can be seen that the RMSE of the second crystal oscillator frequency offset is not less than that of the first crystal oscillator frequency offset when the signal-to-noise ratio is-10 dB, -9.8dB, and the RMSE of the second crystal oscillator frequency offset is less than that of the first crystal oscillator frequency offset when the signal-to-noise ratio is-9.8 dB, 10 dB. The RMSE of the third crystal oscillator frequency offset is smaller than that of the first crystal oscillator frequency offset.

In practical application, the signal-to-noise ratio of a channel through which a terminal sends a signal to a satellite is generally greater than-10 dB, so that the accuracy of the calculated crystal oscillator frequency offset is higher based on the method for determining the crystal oscillator frequency offset provided by the embodiment of the invention.

Referring to fig. 11, fig. 11 is a comparison diagram of the crystal oscillator precision provided by the embodiment of the present invention.

On the basis of fig. 8, in fig. 11, a straight line with a triangle represents a corresponding relationship between the accuracy of the terminal crystal oscillator and the signal-to-noise ratio after the frequency offset pre-compensation is performed based on the first crystal oscillator frequency offset. And the polygonal line with the rhombus represents the corresponding relation between the terminal crystal oscillator precision and the signal-to-noise ratio after the frequency offset pre-compensation is carried out on the basis of the second crystal oscillator frequency offset. The broken line with the round dots represents the corresponding relation between the terminal crystal oscillator precision and the signal-to-noise ratio after the frequency offset pre-compensation is carried out based on the third crystal oscillator frequency offset.

Therefore, the precision of the terminal crystal oscillator after the frequency offset pre-compensation is performed based on the second crystal oscillator frequency offset is smaller than that of the terminal crystal oscillator after the frequency offset pre-compensation is performed based on the first crystal oscillator frequency offset. And the precision of the terminal crystal oscillator after frequency deviation precompensation based on the third crystal oscillator frequency deviation is smaller than that of the terminal crystal oscillator after frequency deviation precompensation based on the first crystal oscillator frequency deviation. Therefore, based on the method for determining the crystal oscillator frequency offset provided by the embodiment of the invention, the accuracy of the calculated crystal oscillator frequency offset is higher. After the frequency offset precompensation is carried out, the precision of the terminal crystal oscillator is low, and the performance of the crystal oscillator after the frequency offset precompensation is good.

Corresponding to the embodiment of the method in fig. 2, referring to fig. 12, fig. 12 is a structural diagram of an apparatus for determining a crystal frequency offset according to an embodiment of the present invention, where the apparatus is applied to a satellite in a communication system, and the communication system further includes: a terminal and a gateway station, the apparatus comprising:

a first sending module 1201, configured to send a synchronization signal block carrying a first synchronization sequence to the terminal, so that when the terminal receives the synchronization signal block, a carrier frequency offset of the synchronization signal block is calculated based on the first synchronization sequence, a second synchronization sequence locally stored in the terminal, and a frequency offset estimation calculation method, and frequency offset precompensation is performed on a transmission frequency when the terminal sends a signal based on the carrier frequency offset, so as to obtain a first transmission frequency; sending the carrier frequency offset to the satellite according to the first transmitting frequency;

a determining module 1202, configured to calculate, when the carrier frequency offset is received, a crystal oscillator frequency offset of the terminal based on the carrier frequency offset and a receiving frequency of the satellite when the carrier frequency offset is received;

a second sending module 1203, configured to send the crystal oscillator frequency offset to the gateway station, so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite;

a third sending module 1204, configured to send the random access response signal to the terminal when receiving the random access response signal, so that the terminal obtains the crystal oscillator frequency offset carried by the random access response signal.

Optionally, the determining module 1202 is specifically configured to calculate a crystal oscillator frequency offset of the terminal based on the carrier frequency offset, a receiving frequency of the satellite when receiving the carrier frequency offset, and a first preset formula; wherein the first preset formula is as follows:

F₁representing the frequency deviation of the crystal oscillator, F₂Representing the carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Indicating the nominal frequency, f, at which the terminal receives the signal₃Representing a receiving frequency at which the satellite receives the carrier frequency offset.

The crystal oscillator frequency offset determining device provided by the embodiment of the invention does not need a temperature sensor, can also determine the crystal oscillator frequency offset of the terminal, and then the terminal can perform frequency offset pre-compensation based on the determined crystal oscillator frequency offset. Furthermore, the accuracy of the frequency offset precompensation of the terminal can be improved.

Corresponding to the embodiment of the method in fig. 3, referring to fig. 13, fig. 13 is a structural diagram of an apparatus for determining a crystal frequency offset according to an embodiment of the present invention, where the apparatus is applied to a terminal in a communication system, and the communication system further includes: a satellite and a gateway station, the apparatus comprising:

a first determining module 1301, configured to calculate, when receiving a synchronization signal block that carries a first synchronization sequence and is sent by the satellite, a carrier frequency offset of the synchronization signal block based on the first synchronization sequence, a locally stored second synchronization sequence, and a frequency offset estimation algorithm;

a second determining module 1302, configured to perform frequency offset precompensation on a transmission frequency when a signal is transmitted based on the carrier frequency offset to obtain a first transmission frequency;

a sending module 1303, configured to send the carrier frequency offset to the satellite according to the first transmitting frequency, so that the satellite calculates a crystal oscillator frequency offset of the terminal based on the carrier frequency offset and a receiving frequency when the satellite receives the carrier frequency offset, and sends the crystal oscillator frequency offset to the gateway station, so that the gateway station sends a random access response signal carrying the crystal oscillator frequency offset to the satellite, and the satellite sends the random access response signal to the terminal;

an obtaining module 1304, configured to obtain the crystal oscillator frequency offset carried by the random access response signal when the random access response signal is received.

Optionally, the second determining module 1302 is specifically configured to calculate a first frequency compensation value when the terminal sends a signal based on the carrier frequency offset, the nominal frequency when the terminal sends a signal, the nominal frequency when the terminal receives a signal, and a second preset formula; wherein the second preset formula is as follows:

a represents the first frequency compensation value, F₂Representing the carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Indicating a nominal frequency at which the terminal receives a signal;

and calculating the sum of the first frequency compensation value and the nominal frequency when the terminal sends the signal as a first transmitting frequency.

Optionally, the apparatus further comprises:

the processing module is used for calculating a second frequency compensation value when the terminal sends a signal based on the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a third preset formula if the crystal oscillator frequency deviation is 0; wherein the third preset formula is as follows:

b represents the second frequency compensation value, F₂Representing the carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Representing the nominal frequency, D, at which the terminal receives the signal₁Representing a relative Doppler shift of the synchronization signal block;

if the crystal oscillator frequency offset is not 0, calculating a second frequency compensation value when the terminal sends a signal based on the crystal oscillator frequency offset, the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a fourth preset formula; wherein the fourth preset formula is:

b represents the second frequency compensation value, F₂Representing the carrier frequency offset, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Representing the nominal frequency, D, at which the terminal receives the signal₁Representing a relative Doppler shift of the synchronization signal block; f₁Representing the crystal oscillator frequency deviation;

calculating the sum of the second frequency compensation value and the nominal frequency when the terminal sends the signal as a second transmitting frequency;

communicating with the satellite at the second transmit frequency.

Corresponding to the embodiment of the method in fig. 6, referring to fig. 14, fig. 14 is a structural diagram of an apparatus for determining a crystal oscillator frequency offset according to an embodiment of the present invention, where the apparatus is applied to a gateway station in a communication system, and the communication system further includes: a satellite and a terminal, the apparatus comprising:

a receiving module 1401, configured to receive a crystal oscillator frequency offset sent by the satellite; the crystal oscillator frequency offset is calculated based on the carrier frequency offset and the receiving frequency of the satellite when the satellite receives the carrier frequency offset sent by the terminal; the carrier frequency offset is calculated by the terminal based on the first synchronization sequence, a second synchronization sequence locally stored by the terminal and a frequency offset estimation algorithm after the terminal receives a synchronization signal block which is sent by the satellite and carries the first synchronization sequence;

a sending module 1402, configured to send a random access response signal carrying the crystal oscillator frequency offset to the satellite, so that the satellite forwards the random access response signal to the terminal, and the terminal obtains the crystal oscillator frequency offset carried by the random access response signal.

An embodiment of the present invention further provides an electronic device, as shown in fig. 15, including a processor 1501, a communication interface 1502, a memory 1503, and a communication bus 1504, where the processor 1501, the communication interface 1502, and the memory 1503 complete mutual communication through the communication bus 1504,

a memory 1503 for storing a computer program;

the processor 1501 is configured to implement the crystal frequency offset determination method according to the foregoing embodiment when executing the program stored in the memory 1503.

The communication bus mentioned in the electronic device may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus.

The communication interface is used for communication between the electronic equipment and other equipment.

The Memory may include a Random Access Memory (RAM) or a Non-Volatile Memory (NVM), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.

The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; but also Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components.

Based on the electronic equipment provided by the embodiment of the invention, the crystal oscillator frequency offset of the terminal can be determined without a temperature sensor, and subsequently, the terminal can perform frequency offset pre-compensation based on the determined crystal oscillator frequency offset. Furthermore, the accuracy of the frequency offset precompensation of the terminal can be improved.

In another embodiment of the present invention, a computer-readable storage medium is further provided, in which a computer program is stored, and the computer program, when executed by a processor, implements the steps of any of the above-mentioned crystal frequency offset determining methods.

In another embodiment of the present invention, there is also provided a computer program product containing instructions, which when run on a computer, causes the computer to execute any of the crystal frequency offset determination methods in the above embodiments.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus, the communication system, the electronic device, the computer-readable storage medium, and the computer program product embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and it suffices to refer to some descriptions of the method embodiments in relation to the relevant points.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A communication system, the communication system comprising: a terminal, a satellite and a gateway station, wherein:

2. A method for determining crystal frequency offset, the method being applied to a satellite in a communication system, the communication system further comprising: a terminal and a gateway station, the method comprising:

3. The method of claim 2, wherein when receiving the carrier frequency offset, calculating a crystal oscillator frequency offset of the terminal based on the carrier frequency offset and a receiving frequency of the satellite when receiving the carrier frequency offset comprises:

calculating the crystal oscillator frequency offset of the terminal based on the carrier frequency offset, the receiving frequency of the satellite when receiving the carrier frequency offset and a first preset formula; wherein the first preset formula is as follows:

4. A method for determining a crystal frequency offset, the method being applied to a terminal in a communication system, the communication system further comprising: a satellite and a gateway station, the method comprising:

5. The method of claim 4, wherein the performing frequency offset pre-compensation on the transmission frequency when the signal is transmitted based on the carrier frequency offset to obtain the first transmission frequency comprises:

calculating a first frequency compensation value when the terminal sends a signal based on the carrier frequency offset, the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a second preset formula; wherein the second preset formula is as follows:

a represents the first frequency compensation value, F₂Represents the aboveFrequency deviation of carrier wave, f₁Indicating the nominal frequency, f, at which the terminal transmits the signal₂Indicating a nominal frequency at which the terminal receives a signal;

6. The method of claim 4, wherein after the obtaining of the crystal oscillator frequency offset carried by the random access response signal when receiving the random access response signal, the method further comprises:

if the crystal oscillator frequency offset is 0, calculating a second frequency compensation value when the terminal sends a signal based on the nominal frequency when the terminal sends the signal, the nominal frequency when the terminal receives the signal and a third preset formula; wherein the third preset formula is as follows:

b represents the second frequency compensation value, F₂Representing the carrier frequency offset, f₁Indicating that the terminal transmits a signalNominal frequency of time, f₂Representing the nominal frequency, D, at which the terminal receives the signal₁Representing a relative Doppler shift of the synchronization signal block; f₁Representing the crystal oscillator frequency deviation;

communicating with the satellite at the second transmit frequency.

7. A method for determining crystal frequency offset, the method being applied to a gateway station in a communication system, the communication system further comprising: a satellite and a terminal, the method comprising:

8. An apparatus for determining a crystal frequency offset, the apparatus being applied to a satellite in a communication system, the communication system further comprising: a terminal and a gateway station, the apparatus comprising:

9. An apparatus for determining crystal frequency offset, the apparatus being applied to a terminal in a communication system, the communication system further comprising: a satellite and a gateway station, the apparatus comprising:

10. An apparatus for determining crystal frequency offset, the apparatus being applied to a gateway station in a communication system, the communication system further comprising: a satellite and a terminal, the apparatus comprising: