Positioning method and computer readable medium

Abstract

The embodiment of the invention provides a positioning method and a computer readable medium. The method comprises the steps that a terminal receives at least four downlink reference signals sent by at least one satellite base station; determining at least four Doppler frequency observation values according to the at least four downlink reference signals, the downlink reference signals being in one-to-one correspondence with the Doppler frequency observation values; and performing terminal positioning according to the at least four Doppler frequency observation values.

Description

Technical Field

[0001] The present application relates to the field of satellite communication technology, and in particular to a positioning method and a computer-readable medium. Background Art

[0002] Low-orbit satellite Internet of Things or narrowband voice services are currently hot topics in the industry. Foreign countries have built a number of low-orbit satellite communication systems, orbital communications (Orbcomm) and Advanced Research and Global Observation Satellite (ARGOS) systems that can provide Internet of Things services, and the Orbcomm and ARGOS systems can specifically provide Internet of Things services.

[0003] Among them, taking the low-orbit satellite communication system as an example, the traditional low-orbit satellite positioning enhancement is mainly achieved by relying on the Global Positioning System (GPS) or Beidou and other systems. For example, it is necessary to simultaneously receive signals sent by at least 4 satellites to achieve positioning. However, for 5G, 6G and other non-terrestrial networks (NTN) and Internet of Things (IOT) systems, due to the small number of NTN IOT satellite base stations, generally only 1 or 2 satellites are covered, making the traditional positioning solutions based on GPS or Beidou and other systems not applicable to NTN IOT systems. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a positioning method and a computer-readable medium, which can realize terminal positioning in the NTN IOT system.

[0005] To solve the above technical problems, the embodiments of the present application are implemented through the following aspects.

[0006] In a first aspect, an embodiment of the present application provides a positioning method, comprising: a terminal receives at least 4 downlink reference signals sent from at least one satellite base station; determines at least 4 Doppler frequency observation values ​​based on the at least 4 downlink reference signals, wherein the downlink reference signals correspond one-to-one to the Doppler frequency observation values; and performs terminal positioning based on the at least 4 Doppler frequency observation values.

[0007] In a second aspect, an embodiment of the present application provides a positioning device, comprising: a receiving module, used to receive at least 4 downlink reference signals sent from at least one satellite base station; a positioning module, used to determine at least 4 Doppler frequency observation values ​​based on the at least 4 downlink reference signals, wherein the downlink reference signals correspond one-to-one to the Doppler frequency observation values; and terminal positioning is performed based on the at least 4 Doppler frequency observation values.

[0008] In a third aspect, an embodiment of the present application provides an electronic device, comprising: one or more processors and a memory storing one or more computer-executable instructions, wherein the one or more computer-executable instructions, when executed by the one or more processors, implement the steps of the method described in the first aspect.

[0009] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which is used to store computer-executable instructions. When the computer-executable instructions are executed by a processor, the steps of the method described in the first aspect are implemented.

[0010] In an embodiment of the present application, the terminal receives at least four downlink reference signals sent from at least one satellite base station, determines at least four Doppler frequency observation values ​​according to the at least four downlink reference signals, and finally performs terminal positioning according to the at least four Doppler frequency observation values. Thus, by using the Doppler positioning method, the purpose of terminal positioning under the NTN IOT system based on at least one satellite base station can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0012] Figure 1 A schematic diagram showing sliding-related values ​​provided in an embodiment of the present application.

[0013] Figure 2 A schematic diagram showing a flow chart of a positioning method provided in an embodiment of the present application is shown.

[0014] Figure 3a One of the schematic diagrams showing the frame structure provided in an embodiment of the present application.

[0015] Figure 3b A second schematic diagram showing a frame structure provided in an embodiment of the present application.

[0016] Figure 3c A third schematic diagram showing a frame structure provided in an embodiment of the present application.

[0017] Figure 4 A schematic structural diagram of a positioning device provided in an embodiment of the present application is shown.

[0018] Figure 5 A schematic diagram of the hardware structure of an electronic device for executing the positioning method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0020] For ease of understanding, the relevant technologies involved in the technical solution provided in this application are explained here.

[0021] (1) Satellite base stations (or satellites) can be divided into low earth orbit (LEO) satellites with a typical altitude of 500-2000 km, medium earth orbit (MEO) satellites with a typical altitude of 8000-20000 km, and geostationary orbit (GEO) satellites with an altitude of about 35786 km. Low earth orbit satellites have the advantages of low cost and low signal attenuation. They are currently the hot spot of satellite broadband Internet of Things and an important research direction for the future 6G.

[0022] The application environment of low-orbit satellite communication is different from that of the ground 5G system. Low-orbit satellites have a relatively fast speed and a large Doppler frequency shift. Depending on the orbit, the speed is between 6.9km / s and 7.9km / s, resulting in a large Doppler frequency and rapid changes. Based on the satellite's 7.9km / s and 2GHz carrier frequency, the maximum Doppler frequency deviation is + / -53KHz, the maximum change rate is 530Hz / s, and the maximum spatial delay change rate is 26.3us / s.

[0023] (2) The current IOT includes two categories: Narrowband (NB)-IOT, which is a licensed frequency band communication technology compatible with 4G, 5G and other mobile communications; and unlicensed frequency band communication technology represented by ZigBee, LoRa, etc., which works in a local area. The frequency band of satellite communication has always been managed by the ITU and uses licensed frequency bands. Therefore, the current satellite IOT needs to use licensed frequency bands for communication.

[0024] The current 4G, 5G or future 6G IOT technologies need to be compatible in order to achieve the integration of the space-ground integrated network, positioning navigation and communication.

[0025] (3) Sliding correlation: Assume that A(n) and B(n) are two sequences. Figure 1 As shown, its sliding correlation value is C(m)=E[A(n+m)*conj(B(n))]=E[A(n)*conj(B(nm))], m=1,...,N. In addition, Figure 1V(m) shown in represents the maximum value among the plurality of sliding-related values ​​C(m).

[0026] Figure 2 1 shows a flow chart of a positioning method 200 provided in an embodiment of the present application. The method 100 can be executed by a terminal. In other words, the method 200 can be executed by software or hardware installed in the terminal. Figure 2 As shown, the method 200 may include the following steps.

[0027] S210: The terminal receives at least four downlink reference signals sent from at least one satellite base station.

[0028] The downlink reference signal may include but is not limited to a narrowband primary synchronization signal (Narrowband Primary Synchronization Signal, NPSS), a narrowband secondary synchronization signal (Narrowband Secondary Synchronization Signal, NSSS), and the like.

[0029] The NPSS transmission period may be 10 ms, and is fixedly sent in the 5th subframe of each radio frame. Figure 3a As shown, the internal format of subframe #5 may include: NPSS is sent on the 3rd to 13th symbols (such as orthogonal frequency division multiplexing (OFDM) symbols) in the time domain, and occupies 11 subcarriers in the frequency domain.

[0030] Correspondingly, the NSSS transmission period may be 20ms, and is fixedly sent in the 9th subframe of the last radio frame of the 20ms period. Figure 3b As shown, the internal format of subframe #9 may include: NSSS is sent on symbols 3 to 13 in the time domain and occupies 12 subcarriers in the frequency domain.

[0031] It is worth noting that, in the case where the downlink reference signal is NPSS or NSSS, the NPSS or NSSS may be independent of the NPSS or NSSS in the related art, or may reuse the NPSS or NSSS in the related art, without limitation. It is understandable that the NPSS in the related art may be used for cell detection, synchronization at the subframe and symbol level, frequency synchronization of carrier and frequency sampling, etc., and the NSSS may also be used for radio frame level time synchronization and physical cell indication.

[0032] In this regard, taking NPSS as an example, for the reception of the NPSS, the terminal can detect and receive the NPSS by cell search, wherein the NPSS can adopt a double-layer structure design of base sequence and code coverage, the base sequence adopts ZC (Zadoff-Chu) sequence, wherein u is 5, l is the symbol position in the subframe, and the value of S(l) is as follows: Figure 3c Based on this, the generation formula of the NPSS can be shown as formula (1).

[0033]

[0034] In addition, as a possible implementation method, the downlink reference signal received by the terminal can be sent by the same satellite base station at different times, or it can be sent by at least two satellite base stations. Thus, the applicability and flexibility of the present application in the NTN IOT system can be greatly improved, and the problem of inconsistent number of communication and navigation satellites caused by single coverage of IOT communication and multiple coverage of navigation in related technologies can be solved.

[0035] For example, assuming that the downlink reference signal is sent by two satellite base stations and the two satellite base stations send a total of four downlink reference signals, then satellite base station A can send two downlink reference signals at different times, and satellite base station B can send two downlink reference signals at different times, or satellite base station A sends one downlink reference signal, and satellite base station B sends three downlink reference signals at different times. As for the sending times of the satellite base stations A and B, they can be the same or different, and there is no limitation here.

[0036] In some embodiments, the reception times of at least 4 downlink reference signals received by the terminal may be close, such as the reception duration of at least 4 downlink reference signals is less than a predetermined value, such as 1 minute, thereby ensuring that the position of the terminal remains approximately unchanged to improve positioning accuracy.

[0037] S220: Determine at least four Doppler frequency observation values ​​according to the at least four downlink reference signals, wherein the downlink reference signals correspond to the Doppler frequency observation values ​​in a one-to-one manner.

[0038] Corresponding to the aforementioned downlink reference signal, in this embodiment, the at least four Doppler frequency observation values ​​can be obtained based on the downlink reference signal sent by the same satellite base station at at least four different times; or, the at least four Doppler frequency observation values ​​can also be obtained based on at least four downlink reference signals sent by at least two different satellite base stations, which is not limited here.

[0039] S230: Perform terminal positioning according to the at least four Doppler frequency observation values.

[0040] There may be multiple ways for the terminal to locate the terminal based on the at least four Doppler frequency observation values. For example, the terminal may determine the terminal location information based on a preset relationship between the Doppler frequency observation value and the terminal location information to achieve terminal positioning.

[0041] For another example, the terminal may construct at least four Doppler frequency observation equations based on the at least four Doppler frequency observation values ​​and a preset relationship, and determine the terminal location information based on the at least four Doppler frequency observation equations to achieve the terminal positioning. The Doppler frequency observation equations correspond to the Doppler frequency observation values ​​one by one, and the preset relationship is configured with an association relationship between the terminal location information and the Doppler frequency observation values. For example, the preset relationship may be as shown in formula (2).

[0042]

[0043] In formula (2), f(x,y,z,f u ) is the Doppler frequency observation value, x = [x, y, z] is the terminal position (i.e., user position or terminal position information), v = [v x ,v y ,v z ] is the speed of the user relative to the satellite base station (i.e., the speed of the satellite base station), f0 is the frequency at which the satellite base station originally transmits the downlink reference signal, and f u is the fixed frequency measurement deviation caused by the receiver clock change at the terminal, c is the speed of light, ε f is a random measurement error and is a constant.

[0044] Based on this, assuming that the number of Doppler frequency observation values ​​is n, then the Doppler frequency observation equation constructed according to the n Doppler frequency observation values ​​and the preset relationship is as shown in formula (3).

[0045]

[0046] The terminal location information can be obtained by solving equation (3) to complete the terminal positioning.

[0047] In this embodiment, there are many ways to solve formula (3). For example, Taylor expansion is performed on each fn function in formula (3), high-order terms are ignored, and only first-order components are retained, thereby obtaining the expansion result shown in formula (4), and then the terminal position is obtained based on the expansion result.

[0048]

[0049] The terminal position information is obtained by solving equation (4) using the least squares method. Assuming that the data to be solved is vector x, the actual measured value is vector f, the error is vector ε, and the transformation matrix from the estimated value to the measured data is A, the fn function shown in equation (5) can be obtained.

[0050] f=AX+ε (5)

[0051] The solution of equation (5) is shown in equation (6).

[0052] X=(A T A) -1 A T f (6)

[0053] in,

[0054]

[0055] Based on this, when solving the terminal location information according to formula (6), an initial position of the terminal can be determined first. After each iteration, a positioning result, such as (x, y, z), can be obtained. If it does not converge, the current (x, y, z) is used as the initial value to continue iterating until the convergence condition is met. At this time, (x, y, z) is the final positioning result. Among them, the condition for determining whether multiple iterations converge is that the two-norm of the difference between the Doppler frequency calculated by the positioning result obtained in a certain iteration and the Doppler frequency actually measured is less than a preset value.

[0056] It is worth noting that in this embodiment, when only one satellite base station can be observed at the terminal (i.e., the observation point), one satellite can be observed continuously for multiple times within a period of observation time to obtain at least 4 Doppler frequency observation values; when the number of observable satellites at the terminal (i.e., the observation point) is more than one, more Doppler frequency observation values ​​can be obtained to improve positioning accuracy.

[0057] In addition, due to the relatively fast motion of low-orbit satellites, the convergence of the positioning solution can be achieved quickly even by observing one star.

[0058] In this embodiment, the terminal receives at least 4 downlink reference signals sent from at least one satellite base station, determines at least 4 Doppler frequency observation values ​​according to the at least 4 downlink reference signals, and finally locates the terminal according to the at least 4 Doppler frequency observation values. Thus, by using the Doppler positioning method, the purpose of positioning under the NTN IOT system based on at least one satellite base station can be achieved, and the cost of the NTN IOT satellite system can be minimized, which effectively solves the problem of single coverage of IOT communication and multiple coverage of navigation in the related art, and the inconsistent number of communication and navigation satellites. For example, the positioning schemes such as GPS involved in the navigation process in the related art need to receive signals sent by at least 4 satellites at the same time to perform positioning, while the number of IOT satellite base stations is very small, and generally only one satellite can be covered.

[0059] In this case, as a possible implementation method, considering that when this embodiment performs positioning based on the Doppler frequency observation equation shown in equation (3) provided above, the parameters that need to be known for positioning solution include the frequency of the satellite signal (i.e., the downlink reference signal), the position and speed of the satellite base station, each satellite base station can perform observations independently, and there is no high requirement for satellite system time synchronization, thereby reducing the complexity of the system.

[0060] When a single satellite is observed multiple times at different times or different satellites are observed to obtain the Doppler frequency observation value for terminal positioning, the fixed frequency measurement deviation f of the terminal receiver can also be realized based on the above formula (3): u The solution is then used to measure the deviation f based on the fixed frequency obtained by the solution. u Perform subsequent positioning solutions to further improve positioning accuracy.

[0061] In another implementation, considering that the satellite mobile communication system may have frequency drift during the positioning process, which may lead to poor positioning accuracy. In this regard, after research, it is considered that the causes of frequency drift may include the following (a)-(c):

[0062] (a) Instability of the local clock of the terminal: If the long-term stability of the clock is 1ppm, without any compensation, the inherent frequency deviation of the S-band (2-4GHz) will reach the kHz level.

[0063] (b) Doppler shift caused by satellite motion: The maximum Doppler shift for uplink and downlink of a stationary terminal can reach the kHz level.

[0064] (c) Due to the movement of the terminal, the uplink and downlink generate Doppler frequency differences. Currently, the IOT system is mainly based on low-speed or static conditions, so the impact of this aspect can be ignored.

[0065] In this regard, in this embodiment, during the positioning process, the aforementioned frequency offset problem can be solved by means of frequency offset correction to improve positioning accuracy.

[0066] For example, in this embodiment, the terminal may use the signal frequency corresponding to the received downlink reference signal as the Doppler frequency value, and determine the Doppler frequency offset value based on the downlink reference signal; then determine the Doppler frequency observation value based on the Doppler frequency value and the Doppler frequency offset value, and then determine the Doppler observation equation based on the Doppler frequency observation value to achieve terminal positioning and ensure the accuracy of the positioning result.

[0067] The process of the terminal determining the Doppler frequency offset value according to the downlink reference signal may include the following (1)-(4).

[0068] (1) The terminal downsamples a received downlink reference signal according to a first sampling rate to obtain a first downlink reference signal sequence, and downsamples a preconfigured local downlink reference signal according to the first sampling rate to obtain a second downlink reference signal sequence.

[0069] Among them, taking the NB-IOT system as an example, the sampling rate of the NB IOT downlink reference signal is 1.92MHz, and 100 radio frames are transmitted per second, so each radio frame contains 19200 sampling points. In this regard, in order to reduce the amount of calculation, the amount of calculation can be reduced by downsampling in this application. That is, when performing downlink reference signal detection, the terminal can downsample the sampling rate from 1.92MHz to 240kHz (i.e., the first sampling rate), and then perform subsequent frequency deviation calculations based on the downsampled signal, thereby reducing the sampling points of each radio frame from 19200 to 2400, and sampling 240 points per subframe, which greatly reduces the amount of calculation in the frequency deviation (i.e., Doppler frequency offset value) calculation process.

[0070] Optionally, the first sampling rate may be other values ​​besides 240 kHz, but it should be noted that the sampling rates before and after downsampling must be integer multiples.

[0071] In addition, the local downlink reference signal is the same as the downlink reference signal sent by the satellite base station for positioning. In this regard, in this embodiment, the local downlink reference signal can be pre-configured in the terminal through protocol agreement, etc., which is not limited here.

[0072] (2) Constructing a plurality of third downlink reference signal sequences corresponding to different frequency offset values ​​according to the first frequency offset value and the second downlink reference signal sequence.

[0073] (3) Determine a maximum value among the sliding correlation values ​​between the third downlink reference signal sequences and the first downlink reference signal sequence as a first sliding correlation value.

[0074] (4) Determine that a second frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value is the Doppler frequency offset value.

[0075] Among them, for the aforementioned (2)-(4), the first frequency deviation value is related to the bandwidth size. For example, in this embodiment, for a bandwidth of 2 GHz, the corresponding maximum Doppler frequency deviation of the Doppler frequency shift is + / -53 KHz. Based on this, in order to facilitate the search for the Doppler frequency offset value, the first frequency deviation value can be less than 53 KHz, such as 7.5 kHz.

[0076] Based on this, the terminal locally constructs a third downlink reference signal sequence (such as NPSS signal) with a frequency deviation of K*7.5kHz. For example, assuming that the second downlink reference signal is NPSS and the third downlink reference signal is NPSS', then NPSS'=NPSS*exp(1j*2*pi*K*7.5kHz*t), K=0,±1,±2,…….

[0077] For each K, NPSS' can slide from the left side to the right side of the first downlink reference signal sequence (which can be denoted as r(t)), and record the maximum value Vm(K) (i.e., the first sliding correlation value) in the sliding correlation value, as well as the K' value that maximizes Vm(K) and the sliding distance m. Then, the second frequency deviation value Nf can be K'*7.5kHz, and the time domain position m of NPSS can be determined.

[0078] In this case, after obtaining the second frequency deviation value, the terminal can correct the Doppler frequency observation value according to the second frequency deviation value, such as adding the second frequency deviation value to the Doppler frequency observation value, and then establish a Doppler frequency observation equation based on the corrected Doppler frequency observation value to perform positioning, thereby improving positioning accuracy.

[0079] In one implementation, considering that the second frequency offset value achieved by the above (1)-(4) is achieved by downsampling, i.e., coarse synchronization (also referred to as integer frequency offset estimation), in order to further improve the accuracy of the positioning result, in this embodiment, fine synchronization (also referred to as fractional frequency offset estimation) can be further performed on the basis of the above coarse synchronization, i.e., after the terminal obtains the first sliding correlation value based on the above (1)-(3), it can further achieve fine frequency synchronization based on the first sliding correlation value, and then achieve Doppler frequency correction based on the result of coarse synchronization and the result of fine synchronization. The implementation process can be shown as follows (41)-(45).

[0080] (41) The terminal may determine a target time deviation according to a sliding distance corresponding to the first sliding related value.

[0081] Optionally, the process of the terminal determining the target time deviation according to the sliding distance corresponding to the first sliding related value may be as shown in (411)-(413) below.

[0082] (411) The received downlink reference signal is sampled again according to the sliding distance corresponding to the first sliding correlation value, the second frequency offset value, and the second sampling rate, and the sampling result and a first number (such as 30) of sampling points before and after the sampling result are used as a seventh downlink reference signal sequence, and the preconfigured local downlink reference signal is sampled at the second sampling rate to obtain an eighth downlink reference signal sequence, wherein the second sampling rate is an integer multiple of the first sampling rate, and the first sampling rate is not less than 140 kHz.

[0083] Regarding the aforementioned (411), it can be understood that after the coarse synchronization in the aforementioned (1)-(3) is completed, although there will be certain errors due to its insufficient accuracy, the approximate position of the NPSS can still be located based on the second frequency deviation value corresponding to the coarse synchronization result. Therefore, in this embodiment, the seventh downlink reference signal sequence can be obtained based on the sliding distance corresponding to the first sliding correlation value and the second frequency deviation value detection (i.e., approximate positioning).

[0084] In this case, the second sampling rate can be understood as the sampling rate recovery value before downsampling in the aforementioned coarse synchronization process, that is, 1.92MHz. That is, the signal processed by the subsequent fine synchronization is the downlink reference signal obtained by sampling at the sampling rate of 1.92MHz, and the 30 sampling point signals before and after it (that is, the aforementioned first number), that is, the seventh downlink reference signal sequence, and the signal length can be 1568 sampling points.

[0085] (412) Calculate a sliding correlation value between the seventh downlink reference signal sequence and the eighth downlink reference signal sequence.

[0086] According to different sampling point positions, sliding correlation values ​​between the second downlink reference signal sequence corresponding to each sampling point position and the eighth downlink reference signal sequence are calculated respectively, and a maximum value among multiple sliding correlation values ​​is selected according to the calculation result.

[0087] (413) Determine the target time deviation according to the sliding distance when the sliding related value is maximum and the sliding distance corresponding to the first sliding related value.

[0088] That is to say, by combining the time offset estimation result (sliding distance m) in the coarse synchronization process and the time offset estimation in the aforementioned (411)-(413), the accurate time offset position (i.e., the target time offset) can be obtained, thereby completing the time offset estimation in the entire cell search process. Based on this, the subsequent (42)-(45) can be further combined to realize precise frequency offset estimation, as follows.

[0089] (42) Sampling the downlink reference signal according to the target time offset, the frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value, and the second sampling rate to obtain a fourth downlink reference signal sequence.

[0090] Considering that an accurate time-frequency estimation value and a second frequency offset value obtained by coarse synchronization have been obtained, the terminal may perform sampling again at the second sampling rate to further obtain a more reliable reference signal sequence for fractional frequency offset estimation.

[0091] (43) Calculating a maximum sliding correlation value between a fifth downlink reference signal sequence and the fourth downlink reference signal sequence, and calculating a maximum sliding correlation value between a sixth downlink reference signal sequence and the fourth downlink reference signal sequence.

[0092] The fifth downlink reference signal sequence and the sixth downlink reference signal sequence are continuous signals determined based on the fourth reference signal sequence, and the difference between the two in the time domain is one symbol.

[0093] For example, assuming that the downlink reference signal is NPSS and two continuous signals are constructed based on the fourth reference signal sequence, namely, the fifth downlink reference signal sequence and the sixth downlink reference signal sequence, then, a PSS signal of multiple symbols continuous in the time domain, namely, the fifth downlink reference signal sequence and the sixth downlink reference signal sequence, can be constructed according to the PSS generation formula.

[0094] For example, the first continuous signal: S(13) is 0, S(3), ..., S(12);

[0095] Second continuous signal: S(3) is 0, S(4), ..., S(12), S(13);

[0096] The two consecutive signals mentioned above differ in time by one symbol.

[0097] (44) Determine a third frequency offset value according to a maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and a maximum sliding correlation value corresponding to the sixth downlink reference signal sequence.

[0098] Optionally, the process of determining the third frequency deviation value may include: the terminal calculates the ratio between the maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and the maximum sliding correlation value corresponding to the sixth downlink reference signal sequence; and then determines the third frequency deviation value based on the ratio and the time domain interval between the fifth downlink reference signal sequence and the sixth downlink reference signal sequence in the time domain.

[0099] For example, assuming that the maximum sliding correlation value corresponding to the fifth downlink reference signal sequence is XS(1) and the maximum sliding correlation value corresponding to the sixth downlink reference signal sequence is XS(2), then the third frequency offset value fn can be calculated according to formula (7).

[0100] XS(1) / XS(2)=exp(j*2*π*fn*T) (7)

[0101] Among them, T is 1 symbol time, that is, T is 1.

[0102] (45) Determine the Doppler frequency offset value according to the second frequency offset value and the third frequency offset value.

[0103] That is, the Doppler frequency offset value is K'*7.5kHz+fn, then the terminal can establish a Doppler frequency observation equation after correcting the Doppler frequency observation value based on the Doppler frequency offset value, thereby improving the accuracy of the terminal positioning result.

[0104] In this embodiment, considering that the terminal does not know the starting position of the system frame during initialization, a blind search is required, that is, all points are detected. If the sliding correlation calculation is performed directly, a very large amount of data processing will be required. Therefore, in order to reduce the computational complexity of downlink reference signal detection such as NPSS, the main synchronization process is divided into two parts: coarse adjustment (i.e., coarse frequency synchronization) and fine adjustment (i.e., fine frequency synchronization) to achieve the estimation of the Doppler frequency offset value, and then the Doppler frequency observation value is corrected based on the estimation result. Therefore, on the one hand, the problem of poor positioning results caused by the large Doppler effect frequency deviation and fast frequency deviation change due to the rapid movement of the satellite can be solved, and high-precision positioning can be achieved. On the other hand, the frequency deviation estimation is achieved by combining coarse synchronization with fine synchronization, so that high-precision frequency deviation estimation can be obtained and the amount of calculation in the frequency deviation estimation process is reduced.

[0105] Of course, taking NB-IOT as an example, this application is applicable to positioning in scenarios such as reduced capability terminals (RedCap), massive machine type communication (mMTC), enhanced machine type communication (eMTC), etc.

[0106] Figure 4 A structural schematic diagram of a positioning device 400 provided in an embodiment of the present application is shown, and the device 400 includes: a receiving module 410, used to receive at least 4 downlink reference signals sent from at least one satellite base station; a positioning module 420, used to determine at least 4 Doppler frequency observation values ​​according to the at least 4 downlink reference signals, wherein the downlink reference signals correspond to the Doppler frequency observation values ​​one by one, and terminal positioning is performed according to the at least 4 Doppler frequency observation values.

[0107] Optionally, the at least 4 Doppler frequency observation values ​​are obtained based on a downlink reference signal sent by the same satellite base station at at least 4 different times; or, the at least 4 Doppler frequency observation values ​​are obtained based on at least 4 downlink reference signals sent by at least two different satellite base stations.

[0108] Optionally, the positioning module 420 performs terminal positioning according to the at least four Doppler frequency observation values, including: constructing at least four Doppler frequency observation equations based on a preset relationship according to the at least four Doppler frequency observation values, the Doppler frequency observation equations corresponding one-to-one to the Doppler frequency observation values, wherein the preset relationship is configured with a correlation relationship between the terminal location information and the Doppler frequency observation values; determining the terminal location information based on the at least four Doppler frequency observation equations to achieve terminal positioning.

[0109] Optionally, the positioning module 420 determines the Doppler frequency observation value based on the downlink reference signal, including: taking the signal frequency corresponding to the received downlink reference signal as the Doppler frequency value, and determining the Doppler frequency offset value based on the downlink reference signal; determining the Doppler frequency observation value based on the Doppler frequency value and the Doppler frequency offset value.

[0110] Optionally, the positioning module 420 determines the Doppler frequency offset value according to the downlink reference signal, including: downsampling the received downlink reference signal at a first sampling rate to obtain a first downlink reference signal sequence, and downsampling the pre-configured local downlink reference signal at the first sampling rate to obtain a second downlink reference signal sequence; constructing multiple third downlink reference signal sequences corresponding to different frequency offset values ​​according to the first frequency offset value and the second downlink reference signal sequence; determining the maximum value of the sliding correlation values ​​between each of the third downlink reference signal sequences and the first downlink reference signal sequence as the first sliding correlation value; and determining the second frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value as the Doppler frequency offset value.

[0111] Optionally, the positioning module 420 determines the second frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value as the Doppler frequency offset value, including: determining the target time offset according to the sliding distance corresponding to the first sliding correlation value; sampling the downlink reference signal according to the target time offset, the frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value, and the second sampling rate to obtain a fourth downlink reference signal sequence; calculating the maximum sliding correlation value between the fifth downlink reference signal sequence and the fourth downlink reference signal sequence, and calculating the maximum sliding correlation value between the sixth downlink reference signal sequence and the fourth downlink reference signal sequence; determining the third frequency offset value according to the maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and the maximum sliding correlation value corresponding to the sixth downlink reference signal sequence; determining the Doppler frequency offset value according to the second frequency offset value and the third frequency offset value; wherein the fifth downlink reference signal sequence and the sixth downlink reference signal sequence are continuous signals determined based on the fourth reference signal sequence, and the two differ by one symbol in the time domain.

[0112] Optionally, the positioning module 420 determines a third frequency deviation value based on the maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and the maximum sliding correlation value corresponding to the sixth downlink reference signal sequence, including: calculating the ratio between the maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and the maximum sliding correlation value corresponding to the sixth downlink reference signal sequence; determining the third frequency deviation value based on the ratio and the time domain interval between the fifth downlink reference signal sequence and the sixth downlink reference signal sequence in the time domain.

[0113] Optionally, the positioning module 420 determines the target time deviation according to the sliding distance corresponding to the first sliding correlation value, including: sampling the received downlink reference signal again according to the sliding distance corresponding to the first sliding correlation value, the second frequency deviation value and the second sampling rate, and taking the sampling result and the first number of sampling points before and after the sampling result as the seventh downlink reference signal sequence, and sampling the pre-configured local downlink reference signal at the second sampling rate to obtain an eighth downlink reference signal sequence, wherein the second sampling rate is an integer multiple of the first sampling rate and the first sampling rate is not less than 140kHz; calculating the sliding correlation value between the seventh downlink reference signal sequence and the eighth downlink reference signal sequence; and determining the target time deviation according to the sliding distance when the sliding correlation value is maximum and the sliding distance corresponding to the first sliding correlation value.

[0114] Optionally, the downlink reference signal includes a narrowband primary synchronization signal NPSS or a narrowband secondary synchronization signal NSSS.

[0115] The device 400 provided in the embodiment of the present application can execute the various methods described in the foregoing method embodiments, and realize the functions and beneficial effects of the various methods described in the foregoing method embodiments, which will not be repeated here.

[0116] Figure 5 A schematic diagram of the hardware structure of an electronic device that implements the embodiment of the present application is shown. Referring to the figure, at the hardware level, the electronic device includes a processor, and optionally, an internal bus, a network interface, and a memory. Among them, the memory may include a memory, such as a high-speed random access memory (Random-Access Memory, RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage, etc. Of course, the electronic device may also include hardware required for other services.

[0117] The processor, the network interface and the memory may be interconnected through an internal bus, which may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one bidirectional arrow is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0118] The memory is used to store the program. Specifically, the program may include a program code, and the program code includes a computer operation instruction. The memory may include a memory and a non-volatile memory, and provides instructions and data to the processor.

[0119] The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it, forming a device for locating the specified user at the logical level. The processor executes the program stored in the memory and is specifically used to execute: Figure 2 The method disclosed in the illustrated embodiment realizes the functions and beneficial effects of each method described in the foregoing method embodiments, which will not be described in detail here.

[0120] The above application Figure 2The method disclosed in the illustrated embodiment can be applied to a processor or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware decoding processor for execution, or a combination of hardware and software modules in the decoding processor for execution. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0121] The electronic device can also execute the methods described in the foregoing method embodiments, and realize the functions and beneficial effects of the methods described in the foregoing method embodiments, which will not be repeated here.

[0122] Of course, in addition to software implementation methods, the electronic device of the present application does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc. That is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0123] The embodiment of the present application also provides a computer-readable storage medium, wherein the computer-readable storage medium stores one or more programs, and when the one or more programs are executed by an electronic device, the electronic device executes Figure 2 The method disclosed in the illustrated embodiment realizes the functions and beneficial effects of each method described in the foregoing method embodiments, which will not be described in detail here.

[0124] The computer-readable storage medium includes a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0125] Furthermore, an embodiment of the present application also provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, and when the program instructions are executed by a computer, the following process is implemented: Figure 1 -The method disclosed in the embodiment shown in FIG3 realizes the functions and beneficial effects of each method described in the previous method embodiments, which will not be described in detail here.

[0126] In short, the above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0127] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0128] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0129] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0130] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

Claims

1. A positioning method, characterized in that: include: The terminal receives at least four downlink reference signals sent from at least one satellite base station; Determine at least four Doppler frequency observation values ​​according to the at least four downlink reference signals, wherein the downlink reference signals correspond to the Doppler frequency observation values ​​one by one; Terminal positioning is performed based on the at least four Doppler frequency observation values.

2. The method according to claim 1, characterized in that The at least four Doppler frequency observation values ​​are obtained based on downlink reference signals sent by the same satellite base station at at least four different times; or, The at least four Doppler frequency observation values ​​are obtained based on at least four downlink reference signals sent by at least two different satellite base stations.

3. The method according to claim 1, characterized in that The performing terminal positioning according to the at least four Doppler frequency observation values ​​comprises: According to the at least four Doppler frequency observation values, at least four Doppler frequency observation equations are constructed based on a preset relationship, wherein the Doppler frequency observation equations correspond to the Doppler frequency observation values ​​one by one, wherein the preset relationship is configured with an association relationship between the terminal location information and the Doppler frequency observation values; The terminal position information is determined based on the at least four Doppler frequency observation equations to achieve the terminal positioning.

4. The method according to any one of claims 1 to 3, characterized in that Determining a Doppler frequency observation value according to the downlink reference signal includes: Using the signal frequency corresponding to the received downlink reference signal as a Doppler frequency value, and determining a Doppler frequency offset value according to the downlink reference signal; The Doppler frequency observation value is determined according to the Doppler frequency value and the Doppler frequency offset value.

5. The method according to claim 4, characterized in that Determining a Doppler frequency offset value according to the downlink reference signal includes: Downsampling the received downlink reference signal according to the first sampling rate to obtain a first downlink reference signal sequence, and downsampling the preconfigured local downlink reference signal according to the first sampling rate to obtain a second downlink reference signal sequence; constructing a plurality of third downlink reference signal sequences corresponding to different frequency offset values ​​according to the first frequency offset value and the second downlink reference signal sequence; determining a maximum value among sliding correlation values ​​between each of the third downlink reference signal sequences and the first downlink reference signal sequence as a first sliding correlation value; Determine that a second frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value is the Doppler frequency offset value.

6. The method according to claim 5, characterized in that Determining that the second frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value is the Doppler frequency offset value, includes: Determine the target time deviation according to the sliding distance corresponding to the first sliding related value; The downlink reference signal is sampled according to the target time offset, the frequency offset value of the third downlink reference signal sequence corresponding to the first sliding correlation value, and the second sampling rate to obtain a fourth downlink reference signal sequence; calculating a maximum sliding correlation value between a fifth downlink reference signal sequence and the fourth downlink reference signal sequence, and calculating a maximum sliding correlation value between a sixth downlink reference signal sequence and the fourth downlink reference signal sequence; Determine a third frequency offset value according to a maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and a maximum sliding correlation value corresponding to the sixth downlink reference signal sequence; Determine the Doppler frequency offset value according to the second frequency offset value and the third frequency offset value; The fifth downlink reference signal sequence and the sixth downlink reference signal sequence are continuous signals determined based on the fourth reference signal sequence, and the difference between the two in the time domain is one symbol.

7. The method according to claim 6, characterized in that Determining a third frequency offset value according to a maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and a maximum sliding correlation value corresponding to the sixth downlink reference signal sequence, comprising: calculating a ratio between a maximum sliding correlation value corresponding to the fifth downlink reference signal sequence and a maximum sliding correlation value corresponding to the sixth downlink reference signal sequence; The third frequency offset value is determined according to the ratio and a time domain interval between the fifth downlink reference signal sequence and the sixth downlink reference signal sequence in the time domain.

8. The method according to claim 7, characterized in that Determining the target time deviation according to the sliding distance corresponding to the first sliding related value includes: The received downlink reference signal is sampled again according to the sliding distance corresponding to the first sliding correlation value, the second frequency offset value and the second sampling rate, and the sampling result and the first number of sampling points before and after the sampling result are used as a seventh downlink reference signal sequence, and the preconfigured local downlink reference signal is sampled according to the second sampling rate to obtain an eighth downlink reference signal sequence, wherein the second sampling rate is an integer multiple of the first sampling rate, and the first sampling rate is not less than 140 kHz; calculating a sliding correlation value between the seventh downlink reference signal sequence and the eighth downlink reference signal sequence; The target time deviation is determined according to the sliding distance when the sliding related value is maximum and the sliding distance corresponding to the first sliding related value.

9. The method according to any one of claims 1 to 8, characterized in that The downlink reference signal includes a narrowband primary synchronization signal NPSS or a narrowband secondary synchronization signal NSSS.

10. A computer-readable medium storing one or more programs, which, when executed by an electronic device, causes the electronic device to perform the steps of the method according to any one of claims 1 to 9.

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