CN114025422A - Open-loop uplink frequency synchronization method and device of low-earth-orbit satellite communication system - Google Patents
Open-loop uplink frequency synchronization method and device of low-earth-orbit satellite communication system Download PDFInfo
- Publication number
- CN114025422A CN114025422A CN202111413211.4A CN202111413211A CN114025422A CN 114025422 A CN114025422 A CN 114025422A CN 202111413211 A CN202111413211 A CN 202111413211A CN 114025422 A CN114025422 A CN 114025422A
- Authority
- CN
- China
- Prior art keywords
- frequency
- terminal
- satellite
- frequency deviation
- uplink
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/0005—Synchronisation arrangements synchronizing of arrival of multiple uplinks
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/0035—Synchronisation arrangements detecting errors in frequency or phase
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/0055—Synchronisation arrangements determining timing error of reception due to propagation delay
- H04W56/0065—Synchronisation arrangements determining timing error of reception due to propagation delay using measurement of signal travel time
- H04W56/007—Open loop measurement
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Astronomy & Astrophysics (AREA)
- Aviation & Aerospace Engineering (AREA)
- General Physics & Mathematics (AREA)
- Radio Relay Systems (AREA)
Abstract
The invention discloses an open-loop uplink frequency synchronization method and device of a low-earth-orbit satellite communication system, which are suitable for the satellite communication system and belong to the technical field of satellite communication; estimating downlink frequency deviation according to each measured frequency deviation between a satellite and a terminal; converting the downlink frequency deviation into an uplink frequency deviation; calculating an uplink frequency precompensation value according to the uplink frequency deviation; and according to the uplink frequency precompensation value, realizing uplink frequency synchronization of the satellite and the terminal. Compared with the closed-loop synchronization process, the time delay is short, the open-loop synchronization is not needed to be carried out by ephemeris information, the problem that the resource waste of a satellite link is large due to frequent ranging of the traditional synchronization method is solved, the accuracy is high, the realization process is simple, and the uplink synchronization problem of the low-orbit satellite communication system can be quickly and efficiently solved.
Description
Technical Field
The invention relates to an open-loop uplink frequency synchronization method and device of a low-earth-orbit satellite communication system, and belongs to the technical field of satellite communication.
Background
The low-earth-orbit satellite communication system can realize communication link at any time and any place in the global range, and solves the problem of coverage blind areas of a ground communication network. As a backup and supplement of the terrestrial communication network, the low-earth satellite communication system becomes an important component of the future personal communication system due to its advantages of global coverage, low power consumption, and the like. The low-orbit satellite is in a high-speed motion state relative to the ground, and the Doppler frequency offset, the Doppler frequency change rate, the transmission time delay and the time delay change rate show a rapid time-varying characteristic along with the movement of the satellite. In the low earth orbit satellite system with the inter-satellite link, the satellite is used as a frequency reference for an uplink, so that in order to avoid time-frequency interference between uplink users, the frequency offset pre-compensation is required when a terminal is in operation before uplink transmission, and the smaller the time-frequency deviation of the terminal reaching the satellite is, the smaller the time-frequency protection interval of a channel can be set, thereby improving the spectrum efficiency and reducing the complexity of satellite processing. However, the high doppler change rate and the high delay change rate of the low earth orbit satellite provide a great challenge to the uplink time-frequency synchronization of the terminal.
At present, in order to solve the uplink frequency synchronization problem of a low-earth satellite communication system, a closed-loop synchronization method is adopted by a ground mobile communication system for reference, the closed-loop synchronization requires the satellite to perform statistics and closed-loop adjustment according to the time-frequency deviation of an uplink physical channel, and because the satellite system has high time delay, the closed-loop adjustment has poor instantaneity and large adjustment error, and the processing complexity of the satellite is increased. Therefore, how to quickly and efficiently implement uplink synchronization of a low-earth-orbit satellite communication system becomes a technical difficulty which needs to be solved urgently.
Disclosure of Invention
The invention aims to provide a method and a device for synchronizing open-loop uplink frequency of a low-earth-orbit satellite communication system. The method is based on the downlink physical channel measurement process to pre-compensate the uplink frequency offset, firstly, the terminal estimates the downlink frequency offset according to the measured frequency offset and the downlink frequency pre-compensation, then converts the uplink frequency offset according to the downlink frequency offset, and finally calculates the uplink frequency pre-compensation value according to the uplink frequency offset. Compared with a closed-loop synchronization process, the method has short time delay, does not need ephemeris information to carry out open-loop synchronization, avoids the problem of great waste of satellite link resources caused by frequent ranging of the traditional synchronization method, has simple realization process, and can quickly and efficiently solve the uplink synchronization problem of the low-orbit satellite communication system.
The invention adopts the following technical scheme for solving the technical problems:
in a first aspect of the present invention, the present invention provides an open-loop uplink frequency synchronization method for a low earth orbit satellite communication system, including:
estimating downlink frequency deviation according to each measured frequency deviation between the satellite and the terminal;
converting the downlink frequency deviation into an uplink frequency deviation;
calculating an uplink frequency precompensation value according to the uplink frequency deviation;
and according to the uplink frequency precompensation value, realizing uplink frequency synchronization of the satellite and the terminal.
Further, the downlink frequency offset includes summing respective frequency offsets between the downlink frequency satellite and the terminal, where the downlink frequency offset is expressed as:
fD＝fd1+fcsat+fcue+fa
wherein f isDIndicating a downlink frequency deviation between the satellite and the terminal; f. ofd1Indicating Doppler frequency deviation generated by relative motion of the satellite and the terminal; f. ofcsatRepresenting frequency deviation caused by a satellite crystal oscillator; f. ofcueIndicating the frequency deviation, f, caused by the terminal crystal oscillatoraIndicating the frequency deviation caused by the terminal frequency offset estimation algorithm.
Further, the downlink frequency deviation further includes pre-compensated summation of each frequency deviation between the satellite and the terminal and the downlink frequency of the terminal, where the downlink frequency deviation is expressed as:
fD＝fd1+fcsat+fcue+fa+fdpre
wherein f isDIndicating a downlink frequency deviation between the satellite and the terminal; f. ofd1Indicating Doppler frequency deviation generated by relative motion of the satellite and the terminal; f. ofcsatRepresenting frequency deviation caused by a satellite crystal oscillator; f. ofcueIndicating the frequency deviation caused by the terminal crystal oscillator; f. ofaRepresenting frequency deviation caused by a terminal frequency offset estimation algorithm; f. ofdpreIndicating the downlink frequency pre-compensation of the terminal.
Further, the method for calculating the downlink frequency precompensation of the terminal includes calculating a doppler change rate of a previous time according to ephemeris information, and multiplying a time difference between a current time and the previous time by the doppler change rate to obtain the downlink frequency precompensation of the terminal, which is represented as:
fdpre＝a(ti-ti-1)
where a denotes the Doppler change rate at the previous time, tiIndicates the current time, ti-1Indicating the previous time instant.
Further, the downlink frequency precompensation of the terminal is represented as:
wherein f isDi-1Indicating a downlink frequency deviation between the satellite and the terminal at a previous time; f. ofDi-2Indicating a downlink frequency deviation between the satellite and the terminal at the first two time instants; t is tiIndicates the current time, ti-1Indicates the previous time, ti-2Indicating the first two time instants.
Further, the uplink frequency offset is expressed as:
fU＝-(fD)*fu0/fd0
wherein f isu0Representing an uplink carrier center frequency; f. ofd0Indicating the downlink carrier center frequency.
Further, the uplink frequency pre-compensation value is expressed as:
fupre＝-(fd2+fcsat+fcue)*fu0/fd0
wherein f isupreRepresenting uplink frequency precompensation; f. ofd2The doppler frequency offset generated for the downlink and uplink time difference T.
In a second aspect of the present invention, the present invention further provides an apparatus for open-loop uplink frequency synchronization of a low earth orbit satellite communication system, the apparatus comprising:
a measuring unit for measuring respective frequency deviations between the satellite and the terminal;
an estimating unit for estimating a downlink frequency deviation from each of the measured frequency deviations between the satellite and the terminal;
a conversion unit, configured to convert the uplink frequency deviation according to the downlink frequency deviation;
the calculation unit is used for calculating an uplink frequency precompensation value according to the uplink frequency deviation;
and the synchronization unit is used for realizing the uplink frequency synchronization of the satellite and the terminal according to the uplink frequency precompensation value.
In a third aspect of the present invention, the present invention further provides an apparatus comprising at least one processor and at least one memory, the processor being configured to perform the method for open loop uplink frequency synchronization of a low earth orbit satellite communication system according to the first aspect of the present invention, and the memory being coupled to the processor.
The invention has the beneficial effects that:
compared with a closed-loop synchronization process, the time delay is short, open-loop synchronization is not needed to be carried out by ephemeris information, the problem that resource waste of a satellite link is large due to frequent ranging of a traditional synchronization method is solved, downlink frequency deviation is estimated through frequency deviation between a satellite and a terminal, and uplink frequency deviation is converted according to the downlink frequency deviation; calculating an uplink frequency pre-compensation value according to the converted uplink frequency deviation, and finally realizing uplink frequency synchronization of the satellite and the terminal according to the uplink frequency pre-compensation value; the method fully utilizes the relation between the uplink frequency deviation and the downlink frequency deviation to finish the correction of the uplink synchronization, has high accuracy and simple realization process, and can quickly and efficiently solve the uplink synchronization problem of the low-orbit satellite communication system.
Drawings
Fig. 1 is a flowchart of an open-loop uplink frequency synchronization method for a low earth orbit satellite communication system according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for open loop uplink frequency synchronization of a low earth orbit satellite communication system in accordance with a preferred embodiment of the present invention;
FIG. 3 is a diagram illustrating a downlink frequency offset measurement interpolation process according to an embodiment of the present invention;
FIG. 4 is a block diagram of an open-loop uplink frequency synchronization apparatus of a low earth orbit satellite communication system according to an embodiment of the present invention;
FIG. 5 is a block diagram of an apparatus in an embodiment of the 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 by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a flowchart of an open-loop uplink frequency synchronization method for a low earth orbit satellite communication system according to an embodiment of the present invention, where as shown in fig. 1, the method includes:
101. estimating downlink frequency deviation according to each measured frequency deviation between the satellite and the terminal;
in this step, the terminal estimates downlink frequency deviation according to the received downlink synchronization channel, broadcast channel, and dedicated channel, wherein each measured frequency deviation between the satellite and the terminal includes a doppler deviation f generated by relative motion between the satellite and the terminald1Frequency deviation f caused by satellite crystal oscillatorcsatFrequency deviation f caused by terminal crystal oscillatorcueAnd frequency deviation f caused by terminal frequency deviation estimation algorithmaAnd the calculation formula is expressed as:
fD＝fd1+fcsat+fcue+fa
wherein f isDIndicating the downlink frequency offset between the satellite and the terminal.
Satellite and terminalDoppler shift f due to relative motiond1The calculation formula is as follows:
wherein f represents a carrier frequency; c represents the speed of light; v represents a relative movement speed between the satellite and the terminal; and theta represents the angle between the satellite and the moving direction of the terminal.
In one embodiment, the frequency deviation f caused by the satellite crystal oscillatorcsatCalculated as 1.995G, 1ppm, the maximum deviation was 1.995 kHz. Frequency deviation f caused by terminal crystal oscillatorcueThe maximum deviation was 1.995 kHz. Frequency deviation f caused by terminal frequency offset estimation algorithmaSmaller, typically not higher than 20 Hz.
102. Converting the downlink frequency deviation into an uplink frequency deviation;
the terminal according to the downlink frequency deviation f of step 101DCalculating the upstream frequency deviation fU(ii) a The calculation formula is as follows:
fU＝-(fD)*fu0/fd0
fU＝-(fd1+fcsat+fcue+fa)*fu0/fd0
wherein f isu0Representing an uplink carrier center frequency; f. ofd0Indicating the downlink carrier center frequency.
103. Calculating an uplink frequency precompensation value according to the uplink frequency deviation;
the uplink frequency pre-compensation value is expressed as:
fupre＝-(fd2+fD-fd1-fa)*fu0/fd0
fupre＝-(fd2+fcsat+fcue)*fu0/fd0
wherein f isupreRepresenting uplink frequency precompensation, which is to realize zero frequency offset of the satellite after terminal compensation under an ideal condition; f. ofd2The doppler frequency offset generated for the downlink and uplink time difference T.
104. And according to the uplink frequency precompensation value, realizing uplink frequency synchronization of the satellite and the terminal.
To achieve uplink frequency synchronization, f is needed according to the above analysisU＝fupreSince the doppler shift increases with increasing frequency, the doppler frequency change rate of the low orbit satellite is assumed to be 500 Hz/s. When T is 0.5s, the Doppler frequency deviation is 500Hz/s 0.5 s-250 Hz.
According to the specification of an S frequency band n70, the uplink frequency is 1695 MHz-1710 MHz, the downlink frequency is 1995 MHz-2020 MHz, and fu0The highest 1710MHz, f is takend0The minimum is 1995 MHz.
Because the satellite crystal oscillator changes little within 0.5s and is generally sealed and insulated, the deviation generated by the satellite crystal oscillator is offset after being converted with the downlink. Similarly, the deviation generated by the terminal crystal oscillator is offset after the downlink conversion.
That is to say that it requires — (f)d1+fa)＝-(fd2) Equal, therefore there are: f. ofd2＝fd1+fa(ii) a The core needs to offset the frequency deviation f caused by the frequency offset estimation algorithmaDoppler frequency deviation f generated by relative motion of satellite and terminald1(ii) a Thus, the present invention provides a Doppler frequency shift f produced by the time difference T between the downlink and uplinkd2To achieve uplink frequency synchronization between the satellite and the terminal.
The deviation of the frequency deviation estimation is 20Hz/fd0*fu0(20/1995 × 1710) Hz 17Hz, total upstream frequency deviation fU＝(250+17)Hz＝267Hz。
Therefore, in this embodiment, the uplink frequency of the terminal is adjusted according to the uplink frequency deviation, i.e., the uplink frequency pre-compensation value, calculated within 0.5s by an error of 267Hz, so as to achieve uplink frequency synchronization between the satellite and the terminal.
Fig. 2 is a flowchart of an open-loop uplink frequency synchronization method for a low earth orbit satellite communication system according to an embodiment of the present invention, and as shown in fig. 2, the method includes:
201. estimating downlink frequency deviation according to each measured frequency deviation between the satellite and the terminal and downlink frequency precompensation;
in this step, the terminal estimates downlink frequency deviation according to the received downlink synchronization channel, broadcast channel, and dedicated channel, wherein each measured frequency deviation between the satellite and the terminal includes a doppler deviation f generated by relative motion between the satellite and the terminald1Frequency deviation f caused by satellite crystal oscillatorcsatFrequency deviation f caused by terminal crystal oscillatorcueAnd frequency deviation f caused by terminal frequency deviation estimation algorithmaIn addition to the above, since the present invention performs downlink frequency precompensation on the satellite side, the actual downlink frequency offset is the measured frequency offset + the downlink frequency precompensation, and the calculation formula of the downlink frequency offset is expressed as:
fD＝fd1+fcsat+fcue+fa+fdpre
wherein f isDIndicating a downlink frequency deviation between the satellite and the terminal; f. ofd1Indicating Doppler frequency deviation generated by relative motion of the satellite and the terminal; f. ofcsatRepresenting frequency deviation caused by a satellite crystal oscillator; f. ofcueIndicating the frequency deviation caused by the terminal crystal oscillator; f. ofaRepresenting frequency deviation caused by a terminal frequency offset estimation algorithm; f. ofdpreIndicating the downlink frequency pre-compensation of the terminal.
In an embodiment, the calculation method of the downlink frequency precompensation of the terminal includes:
calculating the Doppler change rate of the previous moment according to the ephemeris information, and multiplying the time difference between the current moment and the previous moment by the Doppler change rate to obtain downlink frequency precompensation of the terminal, wherein the downlink frequency precompensation is represented as:
fdpre＝a(ti-ti-1)
where a denotes the Doppler change rate at the previous time, tiIndicates the current time, ti-1Indicating the previous time instant.
In another embodiment, the calculation method of the downlink frequency precompensation of the terminal may further include:
downlink frequency precompensation, expressed as:
wherein f isDi-1Indicating a downlink frequency deviation between the satellite and the terminal at a previous time; f. ofDi-2Indicating a downlink frequency deviation between the satellite and the terminal at the first two time instants; t is tiIndicates the current time, ti-1Indicates the previous time, ti-2Indicating the first two time instants.
In some preferred embodiments, in addition to performing interpolation processing by using the downlink frequency deviation at the past two time instants, the present embodiment may also perform interpolation processing by using the measured value of the downlink frequency deviation at the past N time instants, and the interpolation method may refer to the above embodiments.
202. Converting the downlink frequency deviation into an uplink frequency deviation;
the terminal according to the downlink frequency deviation f of step 201DCalculating the upstream frequency deviation fU(ii) a The calculation formula is as follows:
fU＝-(fD)*fu0/fd0
fU＝-(fd1+fcsat+fcue+fa+fdpre)*fu0/fd0
in one embodiment, t is2Time t and3taking the time as an example, t is calculated according to ephemeris information2Doppler change rate at time a, t3Time downlink frequency offset fD3The calculation method comprises the following steps:
fD3＝fD2+a(t3-t2)
in another embodiment, at t1Time t2Time t and3the time is taken as an example, that is, the frequency deviation of the time point of transmitting the uplink signal is linearly estimated according to the frequency deviation of the past 2 downlink bursts, and the frequency deviation is converted into the uplink frequency deviation as the uplink frequency pre-compensation value. As shown in FIG. 3, assume t1Time of day t2The downlink frequency offset of the time is fD1，fD2，t3Time downlink frequency offset fD3The calculation method comprises the following steps:
fD3＝(fD2-fD1)(t3-t1)/(t2-t1)+fD1
203. calculating an uplink frequency precompensation value according to the uplink frequency deviation;
thus, t3Time uplink frequency offset fU3：
fU3＝-fD3*fu0/fd0
The calculation mode of the uplink frequency compensation value is represented as follows:
fupre＝-(fd2+fcsat+fcue)*fu0/fd0
wherein f isupreRepresenting uplink frequency precompensation; f. ofd2The doppler frequency offset generated for the downlink and uplink time difference T.
204. And according to the uplink frequency precompensation value, realizing uplink frequency synchronization of the satellite and the terminal.
And similarly, the uplink frequency synchronization of the satellite and the terminal is realized by adjusting the uplink frequency compensation value.
The precision error of the embodiment of the invention is the sum of the change rate error, the algorithm error and the crystal oscillator error, so the maximum deviation can be controlled not to be higher than 200Hz, and the requirement of uplink frequency synchronization is met.
Fig. 4 is a structural diagram of an open-loop uplink frequency synchronization apparatus of a low earth orbit satellite communication system according to an embodiment of the present invention, and as shown in fig. 4, the apparatus includes:
301. a measuring unit for measuring respective frequency deviations between the satellite and the terminal;
each frequency deviation between the satellite and the terminal measured by the measuring unit comprises a Doppler deviation f generated by the relative motion of the satellite and the terminald1Frequency deviation f caused by satellite crystal oscillatorcsatFrequency deviation f caused by terminal crystal oscillatorcueAnd finallyFrequency deviation f caused by end frequency offset estimation algorithmaAnd the like. 302. An estimating unit for estimating a downlink frequency deviation from each of the measured frequency deviations between the satellite and the terminal;
the estimating unit estimates the measured frequency deviation to obtain a downlink frequency deviation, and the calculation formula is as follows:
fD＝fd1+fcsat+fcue+fa
the estimating unit may further estimate the measured frequency deviation and the downlink frequency precompensation at the satellite side together to obtain a downlink frequency deviation, and the calculation formula is expressed as:
fD＝fd1+fcsat+fcue+fa+fdpre
303. a conversion unit, configured to convert the uplink frequency deviation according to the downlink frequency deviation;
the conversion unit converts the uplink frequency deviation according to the downlink frequency deviation into the following expression:
fU＝-(fD)*fu0/fd0
that is, it can be expressed as:
fU＝-(fd1+fcsat+fcue+fa)*fu0/fd0
or may be represented as:
fU＝-(fd1+fcsat+fcue+fa+fdpre)*fu0/fd0
304. the calculation unit is used for calculating an uplink frequency precompensation value according to the uplink frequency deviation;
the calculation unit calculates the uplink frequency precompensation value according to the uplink frequency deviation as follows:
fupre＝-(fd2+fD-fd1-fa)*fu0/fd0
can also be expressed as:
fupre＝-(fd2+fcsat+fcue)*fu0/fd0
305. and the synchronization unit is used for realizing the uplink frequency synchronization of the satellite and the terminal according to the uplink frequency precompensation value.
The synchronization unit compensates the value f by adjusting the uplink frequencyupreTo achieve uplink frequency synchronization between the satellite and the terminal.
Fig. 5 is an apparatus according to an embodiment of the present invention, the apparatus includes at least one processor 410 and at least one memory 430, the processor 410 is configured to perform an open loop uplink frequency synchronization method of an low earth orbit satellite communication system according to the present invention, the memory 430 is coupled to the processor 410, and the memory 430 is preferably connected to the processor 410 via a bus 420.
Alternatively, it can be understood by those skilled in the art that the structure shown in fig. 5 is only an illustration, and the electronic device may also be a terminal device such as a smart phone (e.g., an Android phone, an iOS phone, etc.), a tablet computer, a palmtop computer, and a Mobile Internet Device (MID), a PAD, and the like. Fig. 5 is a diagram illustrating a structure of the electronic device. For example, the electronic device may also include more or fewer components (e.g., network interfaces, etc.) than shown in FIG. 5, or have a different configuration than shown in FIG. 5.
The memory 430 may be used to store software programs and modules, such as program instructions/modules corresponding to the method and apparatus for synchronization of open-loop uplink frequency of a low earth orbit satellite communication system in the embodiment of the present invention, and the processor 410 executes various functional applications and data processing by running the software programs and modules stored in the memory 430, so as to implement the above-mentioned method for synchronization of open-loop uplink frequency of a low earth orbit satellite communication system. The memory 430 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 430 may further include memory located remotely from the processor 410, which may be connected to the terminal over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof. The memory 430 may be, but not limited to, specifically configured to store information such as parameters of an open loop uplink frequency synchronization method of the low earth orbit satellite communication system.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.
In the description of the present invention, it is to be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "other end", "upper", "one side", "top", "inner", "outer", "front", "center", "both ends", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "disposed," "connected," "fixed," "rotated," and the like are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; the terms may be directly connected or indirectly connected through an intermediate, and may be communication between two elements or interaction relationship between two elements, unless otherwise specifically limited, and the specific meaning of the terms in the present invention will be understood by those skilled in the art according to specific situations.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. An open-loop uplink frequency synchronization method for a low earth orbit satellite communication system, comprising:
estimating downlink frequency deviation according to each measured frequency deviation between the satellite and the terminal;
converting the downlink frequency deviation into an uplink frequency deviation;
calculating an uplink frequency precompensation value according to the uplink frequency deviation;
and according to the uplink frequency precompensation value, realizing uplink frequency synchronization of the satellite and the terminal.
2. The method of claim 1, wherein the downlink frequency offset comprises a sum of frequency offsets between the downlink frequency satellite and the terminal, and the downlink frequency offset is expressed as:
fD＝fd1+fcsat+fcue+fa
wherein f isDIndicating a downlink frequency deviation between the satellite and the terminal; f. ofd1Indicating Doppler frequency deviation generated by relative motion of the satellite and the terminal; f. ofcsatRepresenting frequency deviation caused by a satellite crystal oscillator; f. ofcueIndicating the frequency deviation, f, caused by the terminal crystal oscillatoraIndicating the frequency deviation caused by the terminal frequency offset estimation algorithm.
3. The method of claim 1, wherein the downlink frequency offset further comprises a pre-compensated summation of each frequency offset between the satellite and the terminal and the downlink frequency of the terminal, and the downlink frequency offset is expressed as:
fD＝fd1+fcsat+fcue+fa+fdpre
wherein f isDIndicating a downlink frequency deviation between the satellite and the terminal; f. ofd1Indicating Doppler frequency deviation generated by relative motion of the satellite and the terminal; f. ofcsatRepresenting frequency deviation caused by a satellite crystal oscillator; f. ofcueIndicating the frequency deviation caused by the terminal crystal oscillator; f. ofaRepresenting frequency deviation caused by a terminal frequency offset estimation algorithm; f. ofdpreIndicating the downlink frequency pre-compensation of the terminal.
4. The method as claimed in claim 3, wherein the method for calculating the downlink frequency precompensation of the terminal comprises calculating a doppler change rate at a previous time according to ephemeris information, and multiplying a time difference between a current time and the previous time by the doppler change rate to obtain the downlink frequency precompensation of the terminal, which is expressed as:
fdpre＝a(ti-ti-1)
where a denotes the Doppler change rate at the previous time, tiIndicates the current time, ti-1Indicating the previous time instant.
5. The method of claim 3, wherein the downlink frequency of the terminal is pre-compensated by:
wherein f isDi-1Indicating a downlink frequency deviation between the satellite and the terminal at a previous time; f. ofDi-2Indicating a downlink frequency deviation between the satellite and the terminal at the first two time instants; t is tiIndicates the current time, ti-1Indicates the previous time, ti-2Indicating the first two time instants.
6. An open-loop uplink frequency synchronization method for a low earth orbit satellite communication system according to any of claims 2 to 5, wherein the uplink frequency deviation is expressed as:
fU＝-(fD)*fu0/fd0
wherein f isu0Representing an uplink carrier center frequency; f. ofd0Indicating the downlink carrier center frequency.
7. The method of claim 6, wherein the uplink frequency pre-compensation value is expressed as:
fupre＝-(fd2+fcsat+fcue)*fu0/fd0
wherein f isupreRepresenting uplink frequency precompensation; f. ofd2The doppler frequency offset generated for the downlink and uplink time difference T.
8. An apparatus for open loop uplink frequency synchronization for a low earth orbit satellite communication system, the apparatus comprising:
a measuring unit for measuring respective frequency deviations between the satellite and the terminal;
an estimating unit for estimating a downlink frequency deviation from each of the measured frequency deviations between the satellite and the terminal;
a conversion unit, configured to convert the uplink frequency deviation according to the downlink frequency deviation;
the calculation unit is used for calculating an uplink frequency precompensation value according to the uplink frequency deviation;
and the synchronization unit is used for realizing the uplink frequency synchronization of the satellite and the terminal according to the uplink frequency precompensation value.
9. An apparatus comprising at least one processor configured to perform the method for open loop uplink frequency synchronization for a low earth orbit satellite communication system according to any of claims 1-7 and at least one memory coupled to the processor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111413211.4A CN114025422B (en) | 2021-11-25 | 2021-11-25 | Open loop uplink frequency synchronization method and device for low orbit satellite communication system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111413211.4A CN114025422B (en) | 2021-11-25 | 2021-11-25 | Open loop uplink frequency synchronization method and device for low orbit satellite communication system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114025422A true CN114025422A (en) | 2022-02-08 |
| CN114025422B CN114025422B (en) | 2023-06-30 |
Family
ID=80066674
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111413211.4A Active CN114025422B (en) | 2021-11-25 | 2021-11-25 | Open loop uplink frequency synchronization method and device for low orbit satellite communication system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114025422B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114760171A (en) * | 2022-03-02 | 2022-07-15 | 航天行云科技有限公司 | Uplink frequency compensation method and device in scene of satellite Internet of things and communication terminal |
| WO2024120192A1 (en) * | 2022-12-08 | 2024-06-13 | 大唐移动通信设备有限公司 | Frequency synchronization method and apparatus for satellite communication system, and storage medium |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110545136A (en) * | 2019-07-31 | 2019-12-06 | 成都天奥集团有限公司 | Method for estimating and compensating uplink carrier frequency offset of low-orbit satellite multi-carrier communication system |
| CN111131123A (en) * | 2019-12-12 | 2020-05-08 | 成都天奥集团有限公司 | Method for estimating and compensating uplink sampling frequency offset of low-orbit satellite multi-carrier communication system |
| CN111669345A (en) * | 2019-03-06 | 2020-09-15 | 海能达通信股份有限公司 | Frequency offset compensation method and device |
| CN112540388A (en) * | 2020-11-24 | 2021-03-23 | 湖北三江航天险峰电子信息有限公司 | Satellite communication module and uplink signal Doppler compensation method thereof |
| CN112769468A (en) * | 2021-01-21 | 2021-05-07 | 西安星通通信科技有限公司 | Pre-compensation method for offset frequency of low-earth-orbit satellite mobile terminal |
| WO2021155789A1 (en) * | 2020-02-05 | 2021-08-12 | 维沃移动通信有限公司 | Frequency offset pre-compensation indication method, terminal device and network device |
| CN113422639A (en) * | 2021-07-02 | 2021-09-21 | 东方红卫星移动通信有限公司 | Method and system for synchronization of low-orbit satellite communication system based on position and ephemeris |
-
2021
- 2021-11-25 CN CN202111413211.4A patent/CN114025422B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111669345A (en) * | 2019-03-06 | 2020-09-15 | 海能达通信股份有限公司 | Frequency offset compensation method and device |
| CN110545136A (en) * | 2019-07-31 | 2019-12-06 | 成都天奥集团有限公司 | Method for estimating and compensating uplink carrier frequency offset of low-orbit satellite multi-carrier communication system |
| CN111131123A (en) * | 2019-12-12 | 2020-05-08 | 成都天奥集团有限公司 | Method for estimating and compensating uplink sampling frequency offset of low-orbit satellite multi-carrier communication system |
| WO2021155789A1 (en) * | 2020-02-05 | 2021-08-12 | 维沃移动通信有限公司 | Frequency offset pre-compensation indication method, terminal device and network device |
| CN112540388A (en) * | 2020-11-24 | 2021-03-23 | 湖北三江航天险峰电子信息有限公司 | Satellite communication module and uplink signal Doppler compensation method thereof |
| CN112769468A (en) * | 2021-01-21 | 2021-05-07 | 西安星通通信科技有限公司 | Pre-compensation method for offset frequency of low-earth-orbit satellite mobile terminal |
| CN113422639A (en) * | 2021-07-02 | 2021-09-21 | 东方红卫星移动通信有限公司 | Method and system for synchronization of low-orbit satellite communication system based on position and ephemeris |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114760171A (en) * | 2022-03-02 | 2022-07-15 | 航天行云科技有限公司 | Uplink frequency compensation method and device in scene of satellite Internet of things and communication terminal |
| WO2024120192A1 (en) * | 2022-12-08 | 2024-06-13 | 大唐移动通信设备有限公司 | Frequency synchronization method and apparatus for satellite communication system, and storage medium |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114025422B (en) | 2023-06-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114025422A (en) | Open-loop uplink frequency synchronization method and device of low-earth-orbit satellite communication system | |
| CN110446254A (en) | A kind of uplink timing advance predictably terminal imagination method for satellite communication system | |
| CN109831821B (en) | Satellite mobile communication terminal | |
| CN104316938A (en) | Novel satellite simulator for low-earth-orbit satellite quasi-synchronous communication system | |
| CN110247697B (en) | Method for improving frequency utilization rate of low-earth-orbit communication satellite system | |
| CN113612523B (en) | Uplink time precompensation algorithm, terminal synchronization method and system | |
| CN110474971A (en) | A kind of wide area low-power consumption Internet of Things communication system and its transmission method | |
| CN113422639B (en) | Method and system for synchronization of low-orbit satellite communication system based on position and ephemeris | |
| CN113824517B (en) | Wireless on-orbit self-adaptive amplitude and phase correction system based on digital beam synthesis | |
| CN110324075B (en) | Method for determining time-frequency correction period of low-orbit constellation uplink signal | |
| CN104297765A (en) | Ground terminal simulator used for low-orbit satellite synchronous communication system | |
| WO2016165353A1 (en) | Method and device for adjusting time | |
| WO2021155738A1 (en) | Frequency compensation method and device | |
| CN112769468A (en) | Pre-compensation method for offset frequency of low-earth-orbit satellite mobile terminal | |
| WO2021189183A1 (en) | Ta determination method and apparatus, and terminal device | |
| CN113824485B (en) | Transmission signal compensation method, network side equipment and terminal | |
| CN106019329A (en) | Carrier tracking loop and receiver | |
| CN102547965B (en) | Application system of global positioning system (GPS) time service pulse in medium and high speed sensor network | |
| CN106877965A (en) | A kind of time synchronizing method of micro-base station central station | |
| CN106301526A (en) | A kind of method sending reverse signal and end station | |
| CN111314007A (en) | Frame synchronization system and method for TDMA multiple access | |
| EP4047834A1 (en) | Wireless communication method and device | |
| CN108199799B (en) | A kind of satellite communication terminal digital dock synchronous method and device | |
| CN110943773B (en) | Satellite broadcast demodulating equipment suitable for fixed wing aircraft platform | |
| CN114221843A (en) | Ephemeris-assisted-free polar orbit meteorological satellite LRPT signal automatic acquisition method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address | ||
| CP03 | Change of name, title or address |
Address after: 401120 39-1, Building 1, No. 64, Middle Huangshan Avenue, Yubei District, Chongqing Patentee after: China Star Network Application Co.,Ltd. Address before: 618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing Patentee before: Dongfanghong Satellite Mobile Communication Co.,Ltd. |