WO2024051056A1 - 时频同步方法、装置、设备、存储介质和可读指令产品 - Google Patents

时频同步方法、装置、设备、存储介质和可读指令产品 Download PDF

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WO2024051056A1
WO2024051056A1 PCT/CN2022/144256 CN2022144256W WO2024051056A1 WO 2024051056 A1 WO2024051056 A1 WO 2024051056A1 CN 2022144256 W CN2022144256 W CN 2022144256W WO 2024051056 A1 WO2024051056 A1 WO 2024051056A1
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signal
frequency
time
ssb
das
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PCT/CN2022/144256
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English (en)
French (fr)
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钟家烨
杨子
刘永钦
于吉涛
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京信网络系统股份有限公司
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2662—Symbol synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0061—Error detection codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • H04L25/0242—Channel estimation channel estimation algorithms using matrix methods
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2669—Details of algorithms characterised by the domain of operation
    • H04L27/2672—Frequency domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • H04W56/005—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by adjustment in the receiver

Definitions

  • This application relates to a time-frequency synchronization method, device, equipment, storage medium and readable instruction product.
  • DAS distributed Antenna System
  • Time-frequency synchronization means that the receiving end analyzes and processes the received signal to recover the original clock and frequency of the transmitted signal.
  • a time-frequency synchronization method, device, equipment, storage medium and readable instruction product are provided.
  • a time-frequency synchronization method includes:
  • Time-frequency synchronization processing is performed based on the crystal oscillator offset and the first time domain position difference.
  • a time-frequency synchronization device includes:
  • the first determination module is used to determine the first frequency domain signal and the synchronization signal block SSB index according to the carrier frequency band corresponding to the signal received by the distributed antenna system DAS near-end device;
  • the second determination module is used to determine the estimated frequency offset and channel estimation matrix of the demodulation reference signal DMRS according to the first frequency domain signal and the SSB index;
  • the third determination module is used to estimate the frequency offset and blind frequency offset compensation value based on DMRS to determine the crystal oscillator offset;
  • the fourth determination module is used to determine the first time domain position difference between the main synchronization signal PSS correlation peak and the system frame header according to the first frequency domain signal and the channel estimation matrix;
  • a synchronization module is used to perform time-frequency synchronization processing based on the crystal oscillator offset and the first time domain position difference.
  • a DAS device includes a memory and one or more processors.
  • Computer-readable instructions are stored in the memory. When the computer-readable instructions are executed by the processor, they cause the one or more processors to execute Following steps:
  • Time-frequency synchronization processing is performed according to the crystal oscillator offset and the first time domain position difference.
  • One or more non-volatile computer-readable storage media storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the following steps:
  • Time-frequency synchronization processing is performed according to the crystal oscillator offset and the first time domain position difference.
  • a computer-readable instruction product includes computer-readable instructions that implement the following steps when executed by a processor:
  • Time-frequency synchronization processing is performed according to the crystal oscillator offset and the first time domain position difference.
  • Figure 1 is an application scenario diagram of a time-frequency synchronization method according to one or more embodiments
  • Figure 2 is a schematic flowchart of a time-frequency synchronization method according to one or more embodiments
  • Figure 3 is a schematic flowchart of a time-frequency synchronization method in another embodiment
  • Figure 4 is a schematic diagram of PSS correlation peaks, system frame headers, local frame headers and local frame tails according to one or more embodiments;
  • Figure 5 is a schematic flowchart of a time-frequency synchronization method in another embodiment
  • Figure 6 is a schematic diagram of a PBCH processing flow according to one or more embodiments.
  • Figure 7 is a schematic diagram of an SSB pattern according to one or more embodiments.
  • Figure 8 is a schematic flow chart of a time-frequency synchronization method in another embodiment
  • Figure 9 is a schematic flowchart of a time-frequency synchronization method in another embodiment
  • Figure 10 is a schematic structural diagram of a time-frequency synchronization device according to one or more embodiments.
  • Figure 11 is a schematic structural diagram of a DAS device according to one or more embodiments.
  • Digital DAS can support higher spectrum bandwidth, higher-order modulation methods, more operator channels, and more flexible network deployment methods, and thus is favored by more and more manufacturers.
  • the distance covered by each site is reduced, which means that operators need to deploy more sites, thus greatly increasing the cost of network deployment.
  • each operator adopts a co-construction and sharing operation model.
  • the demand for a co-construction and sharing operation model will increase even further. Therefore, digital DAS products will be a very important wireless communication coverage product in the 5G era.
  • Time-frequency synchronization means that the receiving end analyzes and processes the received signal to recover the original clock and frequency of the transmitted signal.
  • frequency synchronization is to eliminate the frequency difference caused by the transmission process. This difference is mainly caused by the Doppler frequency offset caused by mobility and the frequency offset caused by the different crystal oscillators at the sending and receiving ends.
  • Time synchronization refers to restoring the accurate frame header position at the receiving end. Time-frequency synchronization is one of the important guarantees for physical layer processing in communication systems. Therefore, how to quickly and efficiently restore time-frequency synchronization is of great significance to digital DAS systems and even the entire communication system.
  • the time-frequency synchronization method, device, equipment, storage medium and readable instruction product provided by the embodiment of the present application determines the DMRS estimated frequency offset and blind frequency by performing data processing according to the carrier frequency band corresponding to the signal received by the DAS near-end device.
  • the first time domain position difference between the offset compensation value and the PSS correlation peak and the system frame header is determined, and the crystal oscillator offset is determined based on the DMRS estimated frequency offset and the blind frequency offset compensation value, and then the crystal oscillator offset is determined based on the crystal oscillator offset and the first time domain position difference.
  • the domain position difference is processed in time-frequency synchronization.
  • the embodiment of the present application realizes the time-frequency synchronization of DAS equipment through software without the need to set up additional hardware synchronization circuits, which is beneficial to saving the product cost of DAS equipment, and by combining DMRS
  • the method of frequency synchronization by estimating frequency offset and blind frequency offset compensation value can improve the accuracy of frequency compensation at low signal-to-noise ratio and large frequency offset.
  • low-complexity frame synchronization can be achieved by performing time synchronization through the first time domain position difference between the PSS correlation peak and the system frame header.
  • Figure 1 is an application scenario diagram of the time-frequency synchronization method provided by the embodiment of the present application.
  • the communication system applying the time-frequency synchronization method provided by the embodiment of the present application may include: network device 101, DAS near-end device 102 and at least one DAS remote device 103.
  • the DAS near-end device 102 is used to perform time-frequency synchronization processing on the first radio frequency signal received from the air interface using the time-frequency synchronization method provided by the embodiment of the present application, and then distributes it to at least one DAS remote device 103, so that each DAS The remote device 103 then converts the received signal into a second radio frequency signal for transmission, where the first radio frequency signal may be a signal transmitted by the network device 101.
  • the DAS remote device 103 can perform signal gain processing on the received signal through the signal gain module, and then convert it into a second radio frequency signal through the radio frequency processing module for transmission; of course, the DAS remote device 103 can also process the received signal.
  • the received signal is sent in other ways, which is not limited in the embodiments of this application.
  • the communication system may also include other devices, which are not limited in the embodiments of the present application.
  • the execution subject that executes the DAS near-end device side method may be the DAS near-end device or a device in the DAS near-end device (it should be noted that in the embodiment provided by the present application, the DAS near-end device is The end device is used as an example to describe).
  • the device in the DAS near-end device may be a chip system, a circuit, a module, etc., which is not limited by this application.
  • the DAS near-end equipment involved in the embodiment of this application may include but is not limited to: a baseband processing unit (Building Base band Unit, BBU).
  • BBU Building Base band Unit
  • the DAS remote devices involved in the embodiments of this application may include but are not limited to: Radio Frequency Remote Unit (Remote Radio Unit, RRU).
  • Radio Frequency Remote Unit Remote Radio Unit, RRU
  • Network devices involved in the embodiments of this application may include but are not limited to: base stations and transmission reception points (TRPs).
  • base station also known as radio access network (RAN) equipment
  • RAN radio access network
  • the base transceiver station (BTS) in multiple access (code division multiple access, CDMA) can also be the base station (nodeB, NB) in wideband code division multiple access (WCDMA), or it can be
  • the evolutionary base station (evolutional node B, eNB or eNodeB) in the long term evolution (longterm evolution, LTE), or the relay station or access point, or the base station (gNodeB, gNB) in the 5G network, etc., is not limited here.
  • Figure 2 is a schematic flow chart of a time-frequency synchronization method in an embodiment of the present application.
  • the method is applied to the DAS near-end device in Figure 1 as an example, as shown in Figure 2
  • the method in the embodiment of this application may include the following steps:
  • Step S201 Determine the first frequency domain signal and the synchronization signal block SSB index according to the carrier frequency band corresponding to the signal received by the DAS near-end device of the distributed antenna system.
  • the DAS near-end device can perform first data processing to obtain the first frequency domain signal according to the carrier frequency band corresponding to the signal received from the air interface (or called the first radio frequency signal), where the first data processing can Including: down-frequency processing, primary synchronization signal (Primary Synchronization Signal, PSS) positioning processing, blind frequency offset compensation processing and frequency domain transformation processing; of course, the first data processing can also include other processing, which is not included in the embodiment of the present application. Not limited.
  • PSS Primary Synchronization Signal
  • the carrier frequency band corresponding to any signal in the embodiment of this application may include but is not limited to: the working frequency band and subcarrier spacing corresponding to the signal.
  • the down-frequency processing involved in the embodiment of the present application is used to down-convert the high-frequency radio frequency signal to zero frequency (or called baseband frequency), so that the sampling frequency can be reduced, thereby reducing the amount of data that needs to be processed.
  • the frequency reduction process involved in the embodiment of the present application may belong to the analog-to-digital conversion process; of course, the analog-to-digital conversion process may also include other processing processes, which is not limited in the embodiment of the present application.
  • the PSS signal positioning process involved in the embodiment of the present application is used to determine the target PSS signal in the down-converted signal (or candidate SSB signal), so as to perform blind frequency offset compensation on the signal located behind the target PSS signal. processing and frequency domain transformation processing.
  • SSB synchronization signal block
  • the SSB signal in the embodiment of the present application carries many very important functions, such as carrying cell identities (Identities, ID), time-frequency synchronization, symbol-level frame timing indication, slot-level frame timing indication, cell measurement, and beam signal strength. measurements, and/or signal quality measurements, etc.
  • the SSB signal may include a PSS signal, a secondary synchronization signal (Secondary Synchronization Signal, SSS), and a physical broadcast channel (Physical Broadcast Channel, PBCH) signal.
  • the PSS signal is located at the front end of the SSB signal.
  • the SSS signal and the PSS signal are used to carry the cell ID, complete time-frequency synchronization, and obtain symbol-level timing.
  • SSS signals and PBCH signals can be used to measure cell or beam signal strength/signal quality.
  • the PBCH signal is used to indicate slot/frame timing and carry the Main Information Block (MIB).
  • MIB Main Information Block
  • the blind frequency offset compensation process involved in the embodiment of the present application is used to select a blind frequency offset compensation value from a preset blind frequency offset compensation value set to perform blind frequency offset compensation on the signal to be processed. Since the blind frequency offset compensation value set can freely set the compensation range according to needs, it can also cover large to small frequency offsets at low signal-to-noise ratios, thus achieving low signal-to-noise ratios and large frequency offsets. frequency compensation.
  • the compensation range corresponding to the preset blind frequency offset compensation value set in the embodiment of the present application may include: [-23KHz ⁇ a, 23KHz ⁇ a], where ⁇ a represents the frequency offset error.
  • the frequency domain transformation process involved in the embodiment of the present application is used to convert time domain signals into frequency domain signals.
  • the frequency domain transformation process in the embodiment of the present application may include but is not limited to Fast Fourier Transform (FFT).
  • FFT Fast Fourier Transform
  • the DAS near-end device can also determine the maximum value Lmax of the SSB index of the synchronization signal block based on the carrier frequency band corresponding to the signal received from the air interface (or called the first radio frequency signal), thereby obtaining the SSB index library, and then Determine an SSB index from the SSB index library to perform the following step S202, where the SSB index library contains all indexes with SSB indexes from zero to the maximum value Lmax. For example, assuming that the maximum value of the SSB index is 3, the SSB index library contains: SSB index 0, SSB index 1, SSB index 2 and SSB index 3.
  • the DAS near-end device will select an SSB index from the SSB index library at least once for performing step S202.
  • Step S202 Determine the estimated frequency offset and channel estimation matrix of the demodulation reference signal DMRS according to the first frequency domain signal and the SSB index.
  • the DAS near-end device can determine the channel estimation matrix based on the first frequency domain signal and SSB index determined in the above step S201, and then perform DMRS frequency offset estimation processing according to the channel estimation matrix to obtain the DMRS estimated frequency offset, so that Therefore, the blind frequency offset compensation process can be further modified based on the DMRS estimated frequency offset, thereby improving the accuracy of frequency compensation at low signal-to-noise ratio and large frequency offset.
  • the DAS near-end device can determine the DMRS sequence according to the SSB index; further, the DAS near-end device can determine the channel estimation matrix according to the DMRS sequence and the first frequency domain signal; further, the DAS near-end device can determine the channel estimation matrix according to the channel estimate.
  • the matrix determines the DMRS estimated frequency offset.
  • the DAS near-end device can generate a DMRS sequence based on the lower three-digit value in the SSB index determined in the above step S201; of course, the DMRS sequence can also be generated in other ways, and this is not done in the embodiment of this application. limited.
  • the DAS near-end device can perform channel estimation based on the DMRS sequence and the first frequency domain signal determined in the above step S201, and then the channel estimation matrix can be determined.
  • the DAS near-end device can perform channel estimation by using the least square method (Least Square, LS).
  • Least Square Least Square
  • other methods can also be used for channel estimation, which is not limited in the embodiment of the present application.
  • the DAS near-end device can determine the DMRS estimated frequency offset according to the channel estimation matrix, where the DMRS estimated frequency offset is used as an accuracy correction of the blind frequency offset compensation value.
  • the specific determination method may refer to the determination method in the related art, which is not limited in the embodiments of the present application.
  • the DAS near-end device can also determine the demodulation reference signal DMRS estimated frequency offset and channel estimation matrix in other ways based on the first frequency domain signal and the SSB index, which is not limited in the embodiments of the present application.
  • Step S203 Determine the crystal oscillator offset based on the DMRS estimated frequency offset and blind frequency offset compensation value.
  • the DAS near-end device can determine the crystal oscillator offset based on the DMRS estimated frequency offset determined in the above step S203 and the blind frequency offset compensation value, where the blind frequency offset compensation value is the first value determined in the above step S201.
  • the frequency domain signal is a value selected from a set of preset blind frequency offset compensation values.
  • the crystal oscillator in the embodiment of the present application may include a voltage-controlled crystal oscillator, and accordingly, the crystal oscillator offset may include the voltage offset of the voltage-controlled crystal oscillator.
  • the crystal oscillator offset may also include different offsets, which is not limited in the embodiments of the present application.
  • the DAS near-end device can sum the estimated frequency offset and the blind frequency offset compensation value based on DMRS to obtain the target frequency offset compensation value. Further, the DAS near-end device can determine the offset corresponding to the target frequency offset compensation value as the crystal oscillator offset according to the correspondence between the frequency offset compensation value and the offset, where the frequency offset compensation value and offset The correspondence between quantities is used to indicate the relationship between different frequency offset compensation values and corresponding offset amounts.
  • the DAS near-end device can determine the offset corresponding to both the DMRS estimated frequency offset and the blind frequency offset compensation value based on the correspondence between the estimated frequency offset, frequency offset compensation value and offset.
  • the quantity is the offset of the crystal oscillator, where the correspondence between the estimated frequency offset, the frequency offset compensation value and the offset is used to indicate the relationship between different estimated frequency offsets, frequency offset compensation values and the corresponding offset.
  • Step S204 Determine the first time domain position difference between the primary synchronization signal PSS correlation peak and the system frame header according to the first frequency domain signal and the channel estimation matrix.
  • the DAS near-end device can perform second data processing based on the first frequency domain signal and channel estimation matrix to obtain the first time domain position difference between the PSS correlation peak and the system frame header, where the second data processing It may include: channel equalization processing, frame information acquisition processing and time domain position difference determination processing.
  • the frame information may include but is not limited to system frame information and half-frame indication information; of course, the second data processing may also include other processing, This is not limited in the embodiments of the present application.
  • the PSS correlation peaks involved in the embodiments of this application refer to the PSS correlation peaks corresponding to the correlation peak sliding process during the PSS signal positioning process in the above step S201. It should be understood that the position of the PSS correlation peak can indicate the position of the target PSS signal. Since the PSS signal is located at the front end of the SSB signal, the position of the target PSS signal can also indicate the position of the corresponding SSB signal. Therefore, the PSS correlation peak and The first time domain position difference between system frame headers can also be called the first time domain position difference between the SSB signal and the system frame header.
  • the channel equalization processing involved in the embodiment of the present application is used to make the processed signal closer to the initial signal sent by the signal transmitting end.
  • the acquisition processing of frame information involved in the embodiment of the present application is used to obtain the frame information, and the determination process of the time domain position difference involved in the embodiment of the present application is used to determine the first time domain position difference according to the obtained frame information.
  • Step S205 Perform time-frequency synchronization processing according to the crystal oscillator offset and the first time domain position difference.
  • the DAS near-end device can perform frequency synchronization based on the crystal oscillator offset determined in the above step S203, and time synchronization based on the first time domain position difference determined in the above step S204. It can be seen that the embodiment of the present application adopts The software method realizes the time-frequency synchronization of DAS equipment.
  • the first frequency domain signal and the synchronization signal block SSB index are determined based on the carrier frequency band corresponding to the signal received by the DAS near-end device of the distributed antenna system, and the first frequency domain signal and the SSB index are determined based on the first frequency domain signal and the SSB index.
  • Demodulation reference signal DMRS estimates frequency offset and channel estimation matrix. Further, determine the crystal oscillator offset based on the DMRS estimated frequency offset and blind frequency offset compensation value, and determine the first time between the main synchronization signal PSS correlation peak and the system frame header based on the first frequency domain signal and the channel estimation matrix. Domain position difference. Further, time-frequency synchronization processing is performed according to the crystal oscillator offset and the first time domain position difference.
  • the DMRS estimated frequency offset, blind frequency offset compensation value, PSS correlation peak and system frame header are determined.
  • the first time domain position difference between them is determined, and the crystal oscillator offset is determined based on the DMRS estimated frequency offset and the blind frequency offset compensation value, and then the time-frequency synchronization process is performed based on the crystal oscillator offset and the first time domain position difference.
  • the embodiment of the present application realizes the time-frequency synchronization of DAS equipment through software without the need to set up additional hardware synchronization circuits, which is beneficial to saving the product cost of DAS equipment, and by combining DMRS
  • the method of frequency synchronization by estimating frequency offset and blind frequency offset compensation value can improve the accuracy of frequency compensation at low signal-to-noise ratio and large frequency offset.
  • low-complexity frame synchronization can be achieved by performing time synchronization through the first time domain position difference between the PSS correlation peak and the system frame header.
  • FIG. 3 is a schematic flowchart of a time-frequency synchronization method in another embodiment of the present application.
  • the method of the embodiment of the present application may include the following steps:
  • Step S301 Frequency synchronize the crystal oscillator parameters of the DAS near-end device according to the crystal oscillator offset.
  • the DAS near-end device can adjust the crystal oscillator parameters of the DAS near-end device according to the crystal oscillator offset to perform frequency synchronization, which can effectively reduce the frequency offset caused by the difference in crystal oscillators at the sending and receiving ends.
  • Step S302 Perform time synchronization based on the first time domain position difference and the second time domain position difference.
  • the second time domain position difference in the embodiment of the present application may be the time domain position difference between the PSS correlation peak and the local frame end of the DAS near-end device.
  • the DAS near-end device when the DAS near-end device detects the PSS correlation peak, it can record the time domain position difference between the PSS correlation peak and the local frame end of the DAS near-end device. It should be understood that the DAS near-end device can generate a free-running frame header (or called a local frame header) every preset time period. There is a local frame between two free-running frame headers, and the frame header of the next local frame can be It is the frame tail of the adjacent previous local frame (or called the local frame tail).
  • the DAS near-end device can perform time synchronization based on the sum of the first time domain position difference and the second time domain position difference and comparing it with a preset time length.
  • the preset time length in the embodiment of the present application may be determined according to the half-frame length of the system frame.
  • the DAS near-end device may sum the first time domain position difference and the second time domain position difference to obtain the sum of the differences. If the sum of the differences is consistent with the preset time length, the DAS near-end device can determine that the local frame header of the DAS near-end device is aligned with the system frame header; if the sum of the differences is inconsistent with the preset time length, the DAS near-end device The end device can adjust the position of the local frame header based on the difference between the sum of the differences and the time length, so that the local frame header is aligned with the system frame header to achieve time synchronization.
  • Figure 4 is a schematic diagram of the PSS correlation peak, system frame header, local frame header and local frame tail provided by the embodiment of the present application.
  • the first time domain position difference between the PSS correlation peak and the system frame header t0, the second time domain position difference t1 between the PSS correlation peak and the local frame end of the DAS near-end device if the sum of the differences t between the first time domain position difference t0 and the second time domain position difference t1 ' is equal to the preset time length, then the DAS near-end device can determine that the local frame header is aligned with the system frame header; if the sum of the differences t' between the first time domain position difference t0 and the second time domain position difference t1 is not is equal to the preset time length, the DAS near-end device can adjust the position of the local frame header according to the difference t2 between the sum of differences t' and the time length, so that the local frame header is aligned with the system frame header.
  • the first time domain position difference, the second time domain position difference, and the preset time length can all be represented by the number of data points.
  • the frequency offset caused by the difference in crystal oscillators at the sending and receiving ends can be effectively reduced.
  • low-complexity frame synchronization can be achieved by performing time synchronization based on the first time domain position difference and the second time domain position difference.
  • FIG. 5 is a schematic flowchart of a time-frequency synchronization method in another embodiment of the present application.
  • the correlation of determining the primary synchronization signal PSS in the above step S204 is The relevant content of the first time domain position difference between the peak and the system frame header is introduced.
  • the method of the embodiment of the present application may include the following steps:
  • Step S501 Perform channel equalization processing according to the first frequency domain signal and the channel estimation matrix to obtain a second frequency domain signal.
  • the DAS near-end device can use the equalization algorithm to perform channel equalization processing based on the first frequency domain signal and the channel estimation matrix to obtain the second frequency domain signal, so that the processed second frequency domain signal is closer to the signal sending end.
  • the initial signal sent; among them, the equalization algorithm can include: (Zero Forcing, ZF) equalization algorithm, Minimum Mean Square Error (MMSE), or Maximum Likelihood Sequence Estimation (MLSE).
  • the DAS near-end device can also use other equalization algorithms to perform channel equalization processing based on the first frequency domain signal and the channel estimation matrix, which is not limited in the embodiments of the present application.
  • the DAS near-end device performs channel equalization processing based on the first frequency domain signal and the channel estimation matrix, and can also obtain the signal-to-noise ratio of the first frequency domain signal.
  • the DAS near-end device can update the SSB index from the SSB index library, and return to the above step S202 to determine the DMRS based on the first frequency domain signal and the updated SSB index. Steps to estimate frequency offset and channel estimation matrices. It should be understood that updating the SSB index means re-determining an SSB index from the SSB index database.
  • the DAS near-end device may perform the following step of determining frame information according to the second frequency domain signal in step S502.
  • Step S502 Determine frame information according to the second frequency domain signal.
  • the DAS near-end device can determine frame information based on the second frequency domain signal; where the frame information can include system frame information and half-frame indication information, and the system frame information is used to indicate resources (or resources) used to transmit SSB signals. is the System Frame Number (SFN) corresponding to the SSB signal).
  • SFN System Frame Number
  • the half-frame indication information is used to indicate whether the SSB signal is located in the first half frame or the second half frame of the system frame; of course, the frame information can also include other information. This application This is not limited in the examples.
  • the DAS near-end device decodes the second frequency domain signal to obtain MIB information and physical layer information, and obtains frame information based on the MIB information and physical layer information.
  • FIG. 6 is a schematic diagram of the PBCH processing flow provided by the embodiment of the present application.
  • the signal sending end obtains the PBCH payload according to the Broadcast Control Channel (Broadcast Control Channel, BCCH)-BCH information and PBCH time parameters. Further, the signal transmitting end sequentially performs interleaving, first scrambling, Cyclic Redundancy Check (CRC) addition, Polar coding, rate matching, secondary scrambling, and quadrature phase decomposition on the PBCH payload.
  • the SSB signal is obtained through Quadrature Phase Shift Keying (QPSK) modulation and resource mapping, and then the SSB signal is transmitted.
  • QPSK Quadrature Phase Shift Keying
  • the DAS near-end device performs corresponding decoding processing on the second frequency domain signal to obtain MIB information and physical layer information, where the decoding processing includes but is not limited to at least one of the following: decoding of PBCH, Descramble, QPSK modulation, decode rate matching, decode Polar code, decode CRC.
  • the MIB information may contain part of the system frame number information
  • the physical layer information may contain half-frame indication information, as well as another part of the system frame number information. Therefore, the DAS near-end device can determine the system frame number based on the MIB information and the physical layer information. System frame information, and determining half-frame indication information based on physical layer information.
  • the DAS near-end device can also determine other information based on the MIB information and physical layer information, which is not limited in the embodiments of the present application.
  • the DAS near-end device can update the SSB index from the SSB index library, and return to the above step S202 based on the first frequency domain signal and the updated SSB. Index, the steps to determine the DMRS estimated frequency offset and channel estimation matrix.
  • the DAS near-end device can update the blind frequency offset compensation value, and return to the step of determining the crystal oscillator offset based on the DMRS estimated frequency offset and the updated blind frequency offset compensation value in step S203.
  • Step S503 Determine the first time domain position difference according to the SSB pattern, SSB index and frame information.
  • the DAS near-end device can determine the first time domain between the PSS correlation peak and the system frame header based on the SSB pattern, the SSB index determined in the above step S201, and the frame information determined in the above step S502.
  • the position difference value, where the SSB pattern can be determined by the DAS near-end device according to the carrier frequency band corresponding to the first radio frequency signal.
  • the DAS near-end device can query the correspondence between the preset carrier frequency band and the SSB pattern according to the carrier frequency band corresponding to the first radio frequency signal, and determine the SSB pattern corresponding to the carrier frequency band of the first radio frequency signal, where the preset carrier frequency band
  • the corresponding relationship between carrier frequency bands and SSB patterns is used to indicate the relationship between different carrier frequency bands and corresponding SSB patterns.
  • the DAS near-end device determines the time domain information of the SSB signal based on the SSB pattern, SSB index and frame information, and determines the first time domain position difference based on the time domain information of the SSB signal, where the time domain information includes The time slot and symbol corresponding to the SSB signal.
  • the SSB pattern in the embodiment of the present application is used to indicate the distribution position of the SSB signal in the time domain, and the SSB index is used to indicate the symbol position of the SSB signal within the half-frame.
  • the symbols in the embodiment of this application may be OFDM symbols.
  • the DAS near-end device can determine the system frame information and half-frame indication information where the SSB signal is located based on the frame information, and can determine the location of the system frame information and half-frame indication information based on the SSB pattern and SSB index. Indicates the time slot and symbol corresponding to the SSB signal in the time domain position.
  • Figure 7 is a schematic diagram of an SSB pattern provided by an embodiment of the present application. To facilitate understanding, Figure 7 takes the subcarrier spacing as 15KHz and the SSB pattern as CaseA as an example. As shown in Figure 7, assuming that the SSB pattern is CaseA and the SSB index i SSB is 0, the DAS near-end device can determine based on the SSB pattern and SSB index that the SSB signal is located in subframe 0 (that is, the time slot in the time domain is time slot 0), and the symbols in the time domain include the third symbol to the sixth symbol. It should be understood that when the subcarrier spacing is 15KHz, one system frame includes 10 subframes, one subframe is equal to one time slot, and one time slot includes 14 OFDM symbols.
  • the DAS near-end device can determine the first time domain between the SSB signal and the system frame header based on the time slot and symbol corresponding to the SSB signal.
  • the position difference is the first time domain position difference between the PSS correlation peak and the system frame header.
  • the DAS near-end device obtains the second frequency domain signal by performing channel equalization processing based on the first frequency domain signal and the channel estimation matrix, and determines the frame information based on the second frequency domain signal. Further, the DAS near-end device determines the first time domain position difference between the PSS correlation peak and the system frame header based on the SSB pattern, SSB index and frame information, so that the DAS near-end device can determine the first time domain position difference according to the first time domain position difference. value for time synchronization.
  • FIG. 8 is a schematic flowchart of a time-frequency synchronization method in another embodiment of the present application. Based on the above embodiment, in this embodiment of the present application, the method for determining the first frequency domain signal in the above step S201 is The relevant content will be introduced. As shown in Figure 8, the method in the embodiment of this application may include the following steps:
  • Step S801 Downconvert the target frequency data in the carrier frequency band, and determine candidate SSB signals based on the downconverted frequency data.
  • the DAS near-end device can down-convert the target frequency point data in the carrier frequency band.
  • the target frequency point data can be a candidate SSB frequency point data selected in the carrier frequency band, or it can be a candidate SSB frequency point data selected in the carrier frequency band.
  • the DAS near-end device can down-convert the target frequency data, thereby moving the target frequency data to zero frequency, so that the sampling frequency can be reduced, thereby reducing the amount of data that needs to be processed.
  • the embodiment of the present application can reduce the sampling frequency from 122.88M to 7.68M, and correspondingly can reduce the sampling data from 4096 sampling data to 256 sampling data, thereby reducing the amount of data required for processing. quantity.
  • the DAS near-end device can perform filtering processing on the down-converted frequency point data obtained by the down-conversion processing, so that the frequency point data located within a preset range of zero frequency can be determined as the candidate SSB signal.
  • the DAS near-end device can convert the candidate SSB signal Identified as SSB signal.
  • Step S802 Determine the target PSS signal based on the candidate SSB signal and the local PSS sequence.
  • multiple sets (for example, 3 sets) of local PSS sequences can be preset in the DAS near-end device.
  • Each set of local PSS sequences corresponds to a cell group identification ID, and different sets of PSS sequences correspond to The identifiers within the cell group are different.
  • the DAS near-end device may be preset with local PSS sequence 0, local PSS sequence 1, and local PSS sequence 2, where local PSS sequence 0 corresponds to the cell group identification ID0, and local PSS sequence 1 corresponds to the cell.
  • the intra-group identifier ID1, and the local PSS sequence 2 correspond to the intra-cell group identifier ID2.
  • the DAS near-end device can perform correlation peak sliding processing based on the candidate SSB signal and the local PSS sequence to determine the signal whose correlation peak amplitude between the candidate SSB signal and the local PSS sequence exceeds the first preset threshold. is the target PSS signal. It should be understood that the candidate SSB signal and the local PSS sequence will produce a correlation peak at the synchronization point.
  • the DAS near-end device can set the correlation peak amplitude between the candidate SSB signal and the local PSS sequence 0 to exceed the first preset threshold.
  • a signal with a preset threshold is determined as the target PSS signal.
  • the DAS near-end device can use a local peak-to-average ratio algorithm to perform correlation peak sliding processing.
  • a local peak-to-average ratio algorithm can be used to perform correlation peak sliding processing, which is not limited in the embodiments of the present application.
  • the DAS near-end device can also determine the cell group identifier corresponding to the target PSS signal, so that the DAS near-end device can determine the cell identifier.
  • the DAS near-end device can determine the cell group identifier ID0 corresponding to the local PSS sequence 0 as the corresponding target PSS signal. The identifier within the cell group.
  • Step S803 Compensate the signal located behind the target PSS signal among the candidate SSB signals according to the blind frequency offset compensation value to obtain a compensated signal.
  • the DAS near-end device can perform blind frequency offset compensation processing on the signal located behind the target PSS signal in the candidate SSB signal according to the blind frequency offset compensation value to obtain a compensated signal, where the blind frequency offset compensation value can be DAS
  • the near-end device selects a blind frequency offset compensation value from a set of preset blind frequency offset compensation values.
  • Step S804 Perform frequency domain transformation on the compensated signal to obtain a first frequency domain signal.
  • the DAS near-end device can perform frequency domain transformation processing on the compensated signal obtained in the above step S803 to obtain the first frequency domain signal, so that the DAS near-end device can determine the crystal oscillator offset based on the first frequency domain signal. quantity and the first time domain position difference between the PSS correlation peak and the system frame header.
  • the candidate SSB signal is determined based on the downconverted frequency data obtained by downconverting the target frequency data in the carrier frequency band, and the target PSS signal is determined based on the candidate SSB signal and the local PSS sequence. Further, the signal located behind the target PSS signal in the candidate SSB signal is compensated according to the blind frequency offset compensation value to obtain the compensated signal, and the compensated signal is subjected to frequency domain transformation to obtain the first frequency domain signal, so as to facilitate DAS
  • the near-end device can determine the crystal oscillator offset and the first time domain position difference between the PSS correlation peak and the system frame header according to the first frequency domain signal, so that it can perform the operation based on the crystal oscillator offset and the first time domain position difference. Time-frequency synchronization processing.
  • the DAS near-end device can also determine the cell group identifier based on the first frequency domain signal and the local SSS sequence, and based on the cell group identifier and the intra-cell group identifier corresponding to the target PSS signal, Determine the community ID.
  • multiple groups for example, 336 groups
  • Each group of local SSS sequences corresponds to a cell group identifier
  • different groups of SSS sequences correspond to cell groups.
  • the logo is different.
  • the DAS near-end device may be preset with local SSS sequence 0, local SSS sequence 1, ..., and local SSS sequence 335, where local SSS sequence 0 corresponds to cell group identification ID0 and local SSS sequence 1.
  • the corresponding cell group identifiers ID1,..., and the local SSS sequence 335 corresponds to the cell group identifier ID335.
  • the DAS near-end device can perform correlation peak sliding processing based on the first frequency domain signal and the local SSS sequence, so that the correlation peak amplitude between the first frequency domain signal and the local SSS sequence exceeds the second
  • the signal with the preset threshold is determined as the target SSS signal, and the cell group identifier corresponding to the target SSS signal is determined. It should be understood that the first frequency domain signal and the local SSS sequence will generate a correlation peak at the synchronization point.
  • the DAS near-end device can determine the correlation peak amplitude between the first frequency domain signal and the local SSS sequence 150.
  • the signal whose peak amplitude exceeds the second preset threshold is determined as the target SSS signal, and the cell group ID 150 corresponding to the local SSS sequence 150 is determined as the cell group ID corresponding to the target SSS signal.
  • the DAS near-end device can determine the cell identity based on the cell group identity corresponding to the target SSS signal and the intra-cell group identity corresponding to the target PSS signal, where the cell identity is used for channel estimation and/or decoding. It should be noted that when performing channel estimation, the DAS near-end device can determine the initial DMRS sequence carried in the first frequency domain signal according to the cell identity, so as to facilitate channel estimation with the locally generated DMRS sequence.
  • FIG. 9 is a schematic flowchart of a time-frequency synchronization method in another embodiment of the present application. Based on the above embodiment, the overall flow of the time-frequency synchronization method in this embodiment of the present application is combined with the above embodiment.
  • the method in the embodiment of this application may include the following steps:
  • Step S901 According to the carrier frequency band corresponding to the signal received by the DAS near-end device, traverse the target frequency point data in the carrier frequency band.
  • the target frequency point data may be a candidate SSB frequency point data selected in the carrier frequency band, or may be a frequency point data selected in the carrier frequency band.
  • Step S902 Perform down-conversion processing on the target frequency point data, and perform filtering processing on the down-converted frequency point data obtained by the down-conversion processing to obtain a candidate SSB signal.
  • Step S903 Determine the target PSS signal and the intra-cell group identifier corresponding to the target PSS signal based on the candidate SSB signal and the local PSS sequence.
  • Step S904 Compensate the signal located behind the target PSS signal among the candidate SSB signals according to the blind frequency offset compensation value to obtain a compensated signal.
  • the blind frequency offset compensation value may be a blind frequency offset compensation value selected by the DAS near-end device from a preset blind frequency offset compensation value set.
  • Step S905 Perform frequency domain transformation on the compensated signal to obtain a first frequency domain signal.
  • Step S906 Determine the cell group identity based on the first frequency domain signal and the local SSS sequence, and determine the cell group identity based on the cell group identity and the intra-cell group identity corresponding to the target PSS signal.
  • Step S907 Traverse the SSB indexes in the SSB index library, and determine the DMRS sequence according to the currently selected SSB index.
  • the SSB index library is obtained from the maximum value of the SSB index of the synchronization signal block determined according to the carrier frequency band of the first radio frequency signal.
  • Step S908 Determine a channel estimation matrix according to the DMRS sequence and the first frequency domain signal, and determine the DMRS estimated frequency offset according to the channel estimation matrix.
  • Step S909 Perform channel equalization processing based on the first frequency domain signal and the channel estimation matrix to obtain the signal-to-noise ratio of the second frequency domain signal and the first frequency domain signal.
  • step S910 is executed; if the signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, then the step S907 is returned to traverse another SSB index in the SSB index library (i.e., update SSB index), and determine the DMRS sequence according to the currently selected SSB index.
  • the SSB index library i.e., update SSB index
  • Step S910 Decode the second frequency domain signal to obtain MIB information and physical layer information.
  • step S911 can be executed; if an error occurs in the decoding, the step S907 above is returned to traverse another SSB index in the SSB index library (that is, update the SSB index), and according to the currently selected SSB Index the steps to determine the DMRS sequence.
  • the signal-to-noise ratio of the first frequency domain signal obtained by traversing all SSB indexes in the SSB index library and performing channel equalization processing is less than the preset signal-to-noise ratio threshold, or the second frequency domain signal is decoded If an error occurs at all times, you can traverse the preset blind frequency offset compensation value set to obtain another blind frequency offset compensation value (that is, update the blind frequency offset compensation value), and return to step S904 according to the updated blind frequency offset compensation value.
  • the step of compensating the signal located behind the target PSS signal in the candidate SSB signal is less than the preset signal-to-noise ratio threshold, or the second frequency domain signal is decoded
  • step S901 Another step in the target frequency point data (that is, updating the target frequency point data).
  • Step S911 Obtain frame information according to MIB information and physical layer information.
  • the frame information may include system frame information and half-frame indication information.
  • Step S912 Determine the first time domain position difference between the PSS correlation peak and the system frame header according to the SSB pattern, SSB index and frame information.
  • the SSB pattern may be determined by the DAS near-end device according to the carrier frequency band corresponding to the first radio frequency signal.
  • Step S913 Perform time synchronization based on the first time domain position difference and the second time domain position difference.
  • the second time domain position difference may be the time domain position difference between the PSS correlation peak and the local frame end of the DAS near-end device.
  • Step S914 Estimate the frequency offset and blind frequency offset compensation value based on DMRS, determine the crystal oscillator offset, and perform frequency synchronization on the crystal oscillator parameters of the DAS near-end device based on the crystal oscillator offset.
  • the above-mentioned step S901 in the embodiment of the present application can be executed by the control unit in the DAS near-end device
  • the above-mentioned step S902, step S903 and step S913 can be executed by the FPGA in the DAS near-end device.
  • the above-mentioned step S904-step S912 can be executed by the processor in the DAS near-end device, and the operation of determining the crystal oscillator offset in step S914 can be executed by the processor, and the frequency synchronization operation is performed on the crystal oscillator parameters of the DAS near-end device according to the crystal oscillator offset. Can be executed by FPGA.
  • the embodiment of the present application by performing data processing according to the carrier frequency band corresponding to the signal, the first time domain position between the DMRS estimated frequency offset, the blind frequency offset compensation value and the PSS correlation peak and the system frame header is determined. Difference, and determine the crystal oscillator offset based on the DMRS estimated frequency offset and blind frequency offset compensation value, and then perform time-frequency synchronization processing based on the crystal oscillator offset and the first time domain position difference. It can be seen that compared with the method of using hardware synchronization circuits in traditional technology, the embodiment of the present application can achieve accurate time-frequency synchronization of DAS equipment at low signal-to-noise ratio and large frequency offset through software, which is not only conducive to saving the product cost of DAS equipment. , and also facilitates subsequent iterative updates of new technologies.
  • embodiments of the present application also provide a time-frequency synchronization device for implementing the above-mentioned time-frequency synchronization method.
  • the solution to the problem provided by this device is similar to the solution recorded in the above method. Therefore, the specific limitations in one or more time-frequency synchronization device embodiments provided below can be found in the above embodiments for time-frequency synchronization. The limitations of the method will not be repeated here.
  • Figure 10 is a schematic structural diagram of a time-frequency synchronization device in an embodiment of the present application.
  • the time-frequency synchronization device provided by the embodiment of the present application can be applied to DAS equipment.
  • Time-frequency synchronization The device may include: a first determination module 1001, a second determination module 1002, a third determination module 1003, a fourth determination module 1004 and a synchronization module 1005.
  • the first determination module 1001 is used to determine the first frequency domain signal and the synchronization signal block SSB index according to the carrier frequency band corresponding to the signal received by the distributed antenna system DAS near-end device;
  • the second determination module 1002 is used to determine the estimated frequency offset and channel estimation matrix of the demodulation reference signal DMRS according to the first frequency domain signal and the SSB index;
  • the third determination module 1003 is used to determine the crystal oscillator offset according to the DMRS estimated frequency offset and blind frequency offset compensation value
  • the fourth determination module 1004 is used to determine the first time domain position difference between the primary synchronization signal PSS correlation peak and the system frame header according to the first frequency domain signal and the channel estimation matrix;
  • the synchronization module 1005 is used to perform time-frequency synchronization processing based on the crystal oscillator offset and the first time domain position difference.
  • the fourth determination module 1004 includes:
  • An equalization unit used to perform channel equalization processing based on the first frequency domain signal and the channel estimation matrix to obtain the second frequency domain signal;
  • a first determination unit configured to determine frame information according to the second frequency domain signal; the frame information includes system frame information and half-frame indication information;
  • the second determination unit is used to determine the first time domain position difference according to the SSB pattern, SSB index and frame information, where the SSB pattern is determined according to the carrier frequency band.
  • the first determining unit is specifically used to:
  • the device further includes:
  • the first update module is used to update the SSB index from the SSB index library if an error occurs when decoding the second frequency domain signal, and return to the second determination module 1002 to perform execution based on the first frequency domain signal and the updated SSB. Index, the steps to determine the DMRS estimated frequency offset and channel estimation matrix.
  • the device further includes:
  • the second update module is used to update the blind frequency offset compensation value if errors still occur when decoding the second frequency domain signal after all SSB indexes in the SSB index library are updated, and return to the third determination module 1003 to execute according to DMRS estimates the frequency offset and the updated blind frequency offset compensation value, and determines the crystal oscillator offset.
  • the second determining unit is specifically used to:
  • the time domain information includes the time slot and symbol corresponding to the SSB signal;
  • the first time domain position difference is determined.
  • the equalization unit is further configured to: perform channel equalization processing based on the first frequency domain signal and the channel estimation matrix, and also obtain the signal-to-noise ratio of the first frequency domain signal;
  • the installation also includes:
  • the third update module is used to update the SSB index from the SSB index library if the signal-to-noise ratio is less than the preset signal-to-noise ratio threshold, and return to the second determination module 1002 to perform execution based on the first frequency domain signal and the updated SSB index. , the steps to determine the DMRS estimated frequency offset and channel estimation matrix;
  • the first determination unit performs the step of determining frame information according to the second frequency domain signal.
  • the synchronization module 1005 includes:
  • the first synchronization unit is used to frequency synchronize the crystal oscillator parameters of the DAS near-end device according to the crystal oscillator offset;
  • the second synchronization unit is used to perform time synchronization based on the first time domain position difference and the second time domain position difference; the second time domain position difference is the difference between the PSS correlation peak and the local frame end of the DAS near-end device. Time domain position difference.
  • the second synchronization unit is specifically used for:
  • the time length is determined based on the half-frame length of the system frame
  • the position of the local frame header is adjusted based on the difference between the sum of the differences and the time length.
  • the first determination module 1001 is specifically used to:
  • the compensated signal is subjected to frequency domain transformation to obtain a first frequency domain signal.
  • the device further includes:
  • the fifth determination module is used to determine the cell group identity according to the first frequency domain signal and the local SSS sequence
  • the sixth determination module is used to determine the cell identity based on the cell group identity and the intra-cell group identity corresponding to the target PSS signal; the cell identity is used for channel estimation and/or decoding.
  • the second determination module 1002 is specifically used to:
  • the time-frequency synchronization device provided by the embodiment of the present application can be used to implement the technical solution in the above-mentioned time-frequency synchronization method embodiment of the present application. Its implementation principles and technical effects are similar and will not be described again here.
  • Each module in the above time-frequency synchronization device can be implemented in whole or in part by software, hardware, and combinations thereof.
  • Each of the above modules can be embedded in or independent of the processor in the DAS device in the form of hardware, or can be stored in the memory of the DAS device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.
  • FIG. 11 is a schematic structural diagram of a DAS device in an embodiment of the present application.
  • the DAS device in the embodiment of the present application may include but is not limited to a DAS near-end device.
  • the DAS device includes a processor, memory and communication interface connected through a system bus.
  • the processor of the DAS device is used to provide computing and control capabilities.
  • the memory of the DAS device includes non-volatile storage media and internal memory.
  • the non-volatile storage medium stores an operating system and computer-readable instructions.
  • This internal memory provides an environment for the execution of an operating system and computer-readable instructions in a non-volatile storage medium.
  • the communication interface of the DAS device is used for wired or wireless communication with external devices.
  • FIG. 11 is only a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the DAS equipment to which the solution of the present application is applied.
  • the specific DAS device can May include more or fewer parts than shown, or combine certain parts, or have a different arrangement of parts.
  • a DAS device including a memory and a processor.
  • Computer-readable instructions are stored in the memory.
  • the processor executes the computer-readable instructions, it implements the above-mentioned time-frequency synchronization method embodiments of the present application.
  • the technical solution has similar implementation principles and technical effects and will not be described again here.
  • a computer-readable storage medium on which computer-readable instructions are stored.
  • the technical solutions in the above time-frequency synchronization method embodiments of the present application are implemented, The implementation principles and technical effects are similar and will not be described again here.
  • a computer-readable instruction product including computer-readable instructions.
  • the computer-readable instructions When executed by a processor, the computer-readable instructions implement the technical solution in the above time-frequency synchronization method embodiment of the present application, which implements The principles and technical effects are similar and will not be described again here.
  • the computer readable instructions can be stored in a non-volatile computer.
  • the computer-readable instructions when executed, may include the processes of the above method embodiments.
  • Any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory.
  • Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetic variable memory (magnetoresistive memory) random access memory (MRAM), ferroelectric memory (ferroelectric random access memory (FRAM)), phase change memory (phase change memory (PCM)), graphene memory, etc.
  • Volatile memory may include random access memory (RAM) or external cache memory.
  • RAM can be in many forms, such as static random access memory (static random access memory, SRAM) or dynamic random access memory (dynamic random access memory, DRAM).
  • the processors involved in the various embodiments provided in this application may be general-purpose processors, central processing units, graphics processors, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to this.

Abstract

一种时频同步方法，包括：根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；根据所述第一频域信号和所述SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；根据所述DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；及根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理。

Description

时频同步方法、装置、设备、存储介质和可读指令产品
本申请要求于2022年9月9日提交中国专利局，申请号为2022111021580，申请名称为“时频同步方法、装置、设备、存储介质和程序产品”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及一种时频同步方法、装置、设备、存储介质和可读指令产品。
背景技术
近些年，因为数字信号处理技术的发展以及数字域处理带来的许多好处，分布式天线系统(Distributed Antenna System，DAS)产品的数字化成为了一个主流趋势。数字DAS产品将是第五代移动通信技术(5th-Generation Mobile Communication Technology，5G)时代的一个非常重要的无线通信覆盖产品。
对于数字DAS产品来说，如何对空口的接收信号进行时频同步，一直是被探讨的问题。其中，时频同步是通信系统进行物理层处理的重要保障之一，时频同步是指接收端通过对接收信号进行分析处理，以恢复出原本的发送信号的时钟和频率。
传统技术中，数字DAS产品通常采用硬件同步电路来实现时频同步，但硬件同步电路会增加构建开销，同时在技术演进时需要修改对应电路来完成升级，也进一步提高了运营维护成本。此外，现有的时频同步方法也无法在信号质量较差时仍能保持准确的时频同步。
发明内容
根据本申请公开的各种实施例，提供一种时频同步方法、装置、设备、存储介质和可读指令产品。
一种时频同步方法包括：
根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
根据第一频域信号和SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
根据DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
根据第一频域信号和信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；及
根据晶振偏移量和第一时域位置差值进行时频同步处理。
一种时频同步装置包括：
第一确定模块，用于根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
第二确定模块，用于根据第一频域信号和SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
第三确定模块，用于根据DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
第四确定模块，用于根据第一频域信号和信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；及
同步模块，用于根据晶振偏移量和第一时域位置差值进行时频同步处理。
一种DAS设备，包括存储器和一个或多个处理器，所述存储器中储存有计算机可读指令，所述计算机可读指令被所述处理器执行时，使得所述一个或多个处理器执行以下步骤：
根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
根据所述第一频域信号和所述SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
根据所述DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；及
根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理。
一个或多个存储有计算机可读指令的非易失性计算机可读存储介质，计算机可读指令被一个或多个处理器执行时，使得一个或多个处理器执行以下步骤：
根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
根据所述第一频域信号和所述SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
根据所述DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；及
根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理。
一种计算机可读指令产品，包括计算机可读指令，该计算机可读指令被处理器执行时实现以下步骤：
根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
根据所述第一频域信号和所述SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
根据所述DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；及
根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理。
本申请的一个或多个实施例的细节在下面的附图和描述中提出。本申请的其它特征和优点将从说明书、附图以及权利要求书变得明显。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图。
图1为根据一个或多个实施例中时频同步方法的应用场景图；
图2为根据一个或多个实施例中时频同步方法的流程示意图；
图3为另一个实施例中时频同步方法的流程示意图；
图4为根据一个或多个实施例中PSS相关峰、系统帧头、本地帧头和本地帧尾的示意图；
图5为另一个实施例中时频同步方法的流程示意图；
图6为根据一个或多个实施例中PBCH处理流程的示意图；
图7为根据一个或多个实施例中SSB图样的示意图；
图8为另一个实施例中时频同步方法的流程示意图；
图9为另一个实施例中时频同步方法的流程示意图；
图10为根据一个或多个实施例中时频同步装置的结构示意图；
图11为根据一个或多个实施例中DAS设备的结构示意图。
具体实施方式
为了使本申请的技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行进一步详细说明。应当理解，此处描述的具体实施例仅仅用以解释本申请，并不用于限定本申请。
近些年，因为数字信号处理技术的发展以及数字域处理带来的许多好处，DAS产品的数字化成为 了一个主流趋势。数字DAS可以支持更高的频谱带宽、更高阶的调制方式、更多的运营商通道以及更灵活的布网方式，从而得到越来越多厂商的青睐。特别是在5G时代，由于信号的空口损耗加大，每个站点能够覆盖的距离缩小，意味着运营商需要部署更多的站点，从而大大提高了布网成本。为了减小布网成本，各家运营商通过采用共建共享的运营模式。同时，随着未来毫米波技术的逐渐部署，对于共建共享的运营模式需求会更大的提升。因此，数字DAS产品将是5G时代的一个非常重要的无线通信覆盖产品。
对于数字DAS产品来说，如何对空口的接收信号进行时频同步，一直是被探讨的问题。时频同步是指接收端通过对接收信号进行分析处理，以恢复出原本的发送信号的时钟和频率。其中，频率同步是为了消除传输过程中造成的频率差异，这个差异主要是由移动性产生的多普勒频偏和收发两端晶振不同导致的频偏。时间同步指的是在接收端恢复准确的帧头位置。时频同步是通信系统进行物理层处理的重要保障之一，因此，如何快速且高效地恢复时频同步对数字DAS系统，乃至整个通信系统都有着重要的意义。
传统技术中，数字DAS产品通常采用硬件同步电路来实现时频同步，但硬件同步电路不仅会增加数字DAS产品的生产成本，并且在技术演进时也需要修改对应的硬件同步电路来完成产品升级，还会增加产品的升级成本。可见，传统技术的产品成本较高。
本申请实施例提供的时频同步方法、装置、设备、存储介质和可读指令产品，通过根据DAS近端设备接收到的信号对应的载波频段进行数据处理，确定出DMRS估计频偏、盲频偏补偿值和PSS相关峰与系统帧头之间的第一时域位置差值，并根据DMRS估计频偏和盲频偏补偿值确定晶振偏移量，进而根据晶振偏移量和第一时域位置差值进行时频同步处理。可见，相对于传统技术中采用硬件同步电路的方式，本申请实施例通过软件方式实现了DAS设备的时频同步，无需额外设置硬件同步电路，有利于节省DAS设备的产品成本，而且通过结合DMRS估计频偏和盲频偏补偿值进行频率同步的方式可以提高在低信噪比和大频偏时的频率补偿的准确性。另外通过PSS相关峰与系统帧头之间的第一时域位置差值进行时间同步的方式，可以实现低复杂度的帧同步。
图1为本申请实施例提供的时频同步方法的应用场景图，如图1所示，本申请实施例提供的应用时频同步方法的通信系统可以包括：网络设备101、DAS近端设备102和至少一个DAS拉远设备103。其中，DAS近端设备102用于将从空口接收的第一射频信号采用本申请实施例提供的时频同步方法进行时频同步处理后，分发给至少一个DAS拉远设备103，以便于各DAS拉远设备103再将接收到的信号转换为第二射频信号进行发送，其中，第一射频信号可以为网络设备101发射的信号。
示例性地，DAS拉远设备103可以将接收到的信号通过信号增益模块进行信号增益处理后，再通过射频处理模块转化为第二射频信号进行发送；当然，DAS拉远设备103还可以将接收到的信号通过其它方式进行发送，本申请实施例中对此并不作限定。
当然，该通信系统中还可以包括其它设备，本申请实施例中对此并不作限制。
本申请实施例中，执行DAS近端设备侧方法的执行主体可以是DAS近端设备，也可以是DAS近端设备中的装置(需要说明的是，在本申请提供的实施例中以DAS近端设备为例进行描述的)。示例性地，DAS近端设备中的装置可以是芯片系统、电路或者模块等，本申请不作限制。
本申请实施例中涉及的DAS近端设备可以包括但不限于：基带处理单元(Building Base band Unit，BBU)。
本申请实施例中涉及的DAS拉远设备可以包括但不限于：射频拉远单元(Remote Radio Unit，RRU)。
本申请实施例中涉及的网络设备可以包括但不限于：基站、发送接收点(transmission reception point，TRP)。其中，基站：又称为无线接入网(radio access network，RAN)设备，是一种将终端接入到无线网络的设备，可以是全球移动通讯(global system of mobile communication，GSM)或码分多址(code division multiple access，CDMA)中的基站(base transceiver station，BTS)，也可以是宽带码分多址(wideband code division multiple access，WCDMA)中的基站(nodeB，NB)，还可以是长期演进(longterm evolution，LTE)中的演进型基站(evolutional node B，eNB或eNodeB)，或者中继站或 接入点，或者5G网络中的基站(gNodeB，gNB)等，在此并不限定。
在其中一个实施例中，图2为本申请一个实施例中时频同步方法的流程示意图，本申请实施例中以该方法应用于图1中的DAS近端设备为例进行说明，如图2所示，本申请实施例的方法可以包括以下步骤：
步骤S201、根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引。
本步骤中，DAS近端设备可以根据从空口接收到的信号(或者称之为第一射频信号)对应的载波频段，进行第一数据处理得到第一频域信号，其中，第一数据处理可以包括：降频处理、主同步信号(Primary Synchronization Signal，PSS)定位处理、盲频偏补偿处理和频域变换处理；当然，第一数据处理还可以包括其它处理，本申请实施例中对此并不作限定。
示例性地，本申请实施例中的任意信号对应的载波频段可以包括但不限于：该信号对应的工作频段和子载波间隔。
本申请实施例中涉及的降频处理用于将高频的射频信号降频到零频(或者称之为基带频率)，以便于可以减小采样频率，从而可以降低所需处理的数据量。应理解，本申请实施例中涉及的降频处理过程可以属于模数转换过程；当然，模数转化过程还可以包括其它处理过程，本申请实施例中对此并不作限定。
本申请实施例中涉及的PSS信号定位处理用于确定降频处理后的信号(或者称之为候选SSB信号)中的目标PSS信号，以便于对位于目标PSS信号之后的信号进行盲频偏补偿处理和频域变换处理等处理。
为了便于理解，本申请下述实施例中对同步信号块(Synchronization Signal Block，SSB)信号进行介绍。
本申请实施例中的SSB信号承载着许多很重要的功能，例如，携带小区标识(Identities，ID)、时频同步、符号级帧定时指示、时隙级帧定时指示、小区测量、波束信号强度测量，和/或信号质量测量等。
示例性地，SSB信号可以包括PSS信号、次同步信号(Secondary Synchronization Signal，SSS)和物理广播信道(Physical Broadcast Channel，PBCH)信号组成，PSS信号位于SSB信号中的前端位置。其中，SSS信号和PSS信号用于携带小区ID、完成时频同步，以及获取符号级定时。SSS信号和PBCH信号可用于小区或波束信号强度/信号质量的测量。PBCH信号用于指示时隙/帧定时，以及承载主消息块(Main Information Block，MIB)。
本申请实施例中涉及的盲频偏补偿处理用于从预设盲频偏补偿值集合中选择一个盲频偏补偿值对待处理信号进行盲频偏补偿。由于盲频偏补偿值集合可以根据需求自由地设定补偿范围，因此，在低信噪比时也可以覆盖大频偏到小频偏，从而可以实现在低信噪比和大频偏时的频率补偿。
示例性地，本申请实施例中的预设盲频偏补偿值集合对应的补偿范围可以包括：[-23KHz±Δa，23KHz±Δa]，其中，Δa代表频偏误差。
本申请实施例中涉及的频域变换处理用于将时域信号转换为频域信号。示例性地，本申请实施例中的频域变换处理可以包括但不限于快速傅里叶变换(Fast Fourier Transform，FFT)。
本步骤中，DAS近端设备根据从空口接收到的信号(或者称之为第一射频信号)对应的载波频段，还可以确定同步信号块SSB索引的最大值Lmax，从而得到SSB索引库，然后从SSB索引库中确定一个SSB索引，以便于执行下述步骤S202，其中，SSB索引库中包含SSB索引为零到最大值Lmax的所有索引。例如，假设SSB索引的最大值为3，则SSB索引库中包含：SSB索引为0、SSB索引为1、SSB索引为2以及SSB索引为3。
应理解，DAS近端设备在执行本申请实施例的时频同步方法的过程中会从SSB索引库中至少选择一次SSB索引用于执行步骤S202。
步骤S202、根据第一频域信号和SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵。
本步骤中，DAS近端设备可以根据上述步骤S201中确定的第一频域信号和SSB索引，确定信道 估计矩阵，然后根据信道估计矩阵进行DMRS频偏估计处理便可得到DMRS估计频偏，以便于可以根据DMRS估计频偏对盲频偏补偿处理进行进一步地修正，从而可以提高在低信噪比和大频偏时的频率补偿的准确性。
可选地，DAS近端设备可以根据SSB索引确定DMRS序列；进一步地，DAS近端设备可以根据DMRS序列和第一频域信号，确定信道估计矩阵；进一步地，DAS近端设备可以根据信道估计矩阵确定DMRS估计频偏。
本实现方式中，DAS近端设备可以根据上述步骤S201中所确定的SSB索引中的低三位数值生成DMRS序列；当然，也可以通过其它方式生成DMRS序列，本申请实施例中对此并不作限定。
进一步地，DAS近端设备可以根据DMRS序列和上述步骤S201中所确定的第一频域信号进行信道估计，便可确定信道估计矩阵。示例性地，本申请实施例中DAS近端设备可以通过采用最小二乘法(Least Square，LS)进行信道估计，当然还可以采用其它方式进行信道估计，本申请实施例中对此并不作限定。
进一步地，DAS近端设备可以根据信道估计矩阵，确定DMRS估计频偏，其中，DMRS估计频偏作为盲频偏补偿值的精度修正。具体的确定方式可以参考相关技术中的确定方式，本申请实施例中对此并不作限定。
当然，DAS近端设备根据第一频域信号和SSB索引，还可以通过其它方式确定解调参考信号DMRS估计频偏和信道估计矩阵，本申请实施例中对此并不作限定。
步骤S203、根据DMRS估计频偏和盲频偏补偿值，确定晶振偏移量。
本步骤中，DAS近端设备可以根据上述步骤S203中确定的DMRS估计频偏，以及盲频偏补偿值，确定晶振偏移量，其中，盲频偏补偿值为上述步骤S201中在确定第一频域信号时从预设盲频偏补偿值集合中选择的值。
示例性地，本申请实施例中的晶振可以包括压控晶振，对应地，晶振偏移量可以包括压控晶振的电压偏移量。当然，若晶振采用其它形式的晶振，对应的晶振偏移量也可以包括不同的偏移量，本申请实施例中对此并不作限定。
一种可能的实现方式中，DAS近端设备可以根据DMRS估计频偏与盲频偏补偿值求和，得到目标频偏补偿值。进一步地，DAS近端设备可以根据频偏补偿值与偏移量之间的对应关系，确定与目标频偏补偿值对应的偏移量为晶振偏移量，其中，频偏补偿值与偏移量之间的对应关系用于指示不同频偏补偿值与对应的偏移量之间的关系。
另一种可能的实现方式中，DAS近端设备可以根据估计频偏、频偏补偿值与偏移量之间的对应关系，确定与DMRS估计频偏和盲频偏补偿值均对应的偏移量为晶振偏移量，其中，估计频偏、频偏补偿值与偏移量之间的对应关系用于指示不同估计频偏和频偏补偿值与对应的偏移量之间的关系。
步骤S204、根据第一频域信号和信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值。
本步骤中，DAS近端设备可以根据第一频域信号和信道估计矩阵进行第二数据处理，得到PSS相关峰与系统帧头之间的第一时域位置差值，其中，第二数据处理可以包括：信道均衡处理、帧信息的获取处理和时域位置差值的确定处理，帧信息可以包括但不限于系统帧信息和半帧指示信息；当然，第二数据处理还可以包括其它处理，本申请实施例中对此并不作限定。
本申请实施例中涉及的PSS相关峰是指在上述步骤S201中的PSS信号定位处理过程中进行相关峰滑动处理时对应的PSS相关峰。应理解，PSS相关峰的位置可以指示目标PSS信号的位置，由于PSS信号位于SSB信号中的前端位置，因此，目标PSS信号的位置也可以指示对应的SSB信号的位置，故而，PSS相关峰与系统帧头之间的第一时域位置差值也可以称之为SSB信号与系统帧头之间的第一时域位置差值。
本申请实施例中涉及的信道均衡处理用于使得处理得到的信号更加接近信号发送端所发送的初始信号。
本申请实施例中涉及的帧信息的获取处理用于获取帧信息，本申请实施例中涉及的时域位置差值 的确定处理用于根据获取的帧信息确定第一时域位置差值。
步骤S205、根据晶振偏移量和第一时域位置差值进行时频同步处理。
本步骤中，DAS近端设备可以根据上述步骤203中确定的晶振偏移量进行频率同步，以及根据上述步骤S204中确定的第一时域位置差值进行时间同步，可见，本申请实施例通过软件方式实现了DAS设备的时频同步。
本申请实施例中，通过根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引，并根据第一频域信号和SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵。进一步地，根据DMRS估计频偏和盲频偏补偿值，确定晶振偏移量，并根据第一频域信号和信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值。进一步地，根据晶振偏移量和第一时域位置差值进行时频同步处理。综上所述，本申请实施例中，通过根据DAS近端设备接收到的信号对应的载波频段进行数据处理，确定出DMRS估计频偏、盲频偏补偿值和PSS相关峰与系统帧头之间的第一时域位置差值，并根据DMRS估计频偏和盲频偏补偿值确定晶振偏移量，进而根据晶振偏移量和第一时域位置差值进行时频同步处理。可见，相对于传统技术中采用硬件同步电路的方式，本申请实施例通过软件方式实现了DAS设备的时频同步，无需额外设置硬件同步电路，有利于节省DAS设备的产品成本，而且通过结合DMRS估计频偏和盲频偏补偿值进行频率同步的方式可以提高在低信噪比和大频偏时的频率补偿的准确性。另外通过PSS相关峰与系统帧头之间的第一时域位置差值进行时间同步的方式，可以实现低复杂度的帧同步。
在其中一个实施例中，图3为本申请另一个实施例中时频同步方法的流程示意图，在上述实施例的基础上，本申请实施例中对上述步骤S205中根据晶振偏移量和第一时域位置差值进行时频同步处理的相关内容进行介绍，如图3所示，本申请实施例的方法可以包括以下步骤：
步骤S301、根据晶振偏移量对DAS近端设备的晶振参数进行频率同步。
本步骤中，DAS近端设备可以根据晶振偏移量调整DAS近端设备的晶振参数，以进行频率同步，从而可以有效地减小收发两端由于晶振差异产生的频偏。
步骤S302、根据第一时域位置差值和第二时域位置差值进行时间同步。
本申请实施例中的第二时域位置差值可以为PSS相关峰与DAS近端设备的本地帧尾之间的时域位置差。
需要说明的是，DAS近端设备在检测到PSS相关峰时可以记录PSS相关峰与DAS近端设备的本地帧尾之间的时域位置差。应理解，DAS近端设备可以每隔预设时长生成一个自由振荡帧头(或者称之为本地帧头)，两个自由振荡帧头之间为一个本地帧，下一个本地帧的帧头可以为相邻的上一个本地帧的帧尾(或者称之为本地帧尾)。
本步骤中，DAS近端设备可以根据第一时域位置差值与第二时域位置差值的总和，与预设的时间长度进行对比的方式，进行时间同步。示例性地，本申请实施例中的预设的时间长度可以为根据系统帧的半帧长度确定的。
可选地，DAS近端设备可以对第一时域位置差值和第二时域位置差值求和，得到差值之和。若差值之和与预设的时间长度一致，则DAS近端设备可以确定DAS近端设备的本地帧头与系统帧头对齐；若差值之和与预设的时间长度不一致，则DAS近端设备可以根据差值之和与时间长度之间的差值，调整本地帧头的位置，从而使得本地帧头与系统帧头对齐，以实现时间同步。
图4为本申请实施例提供的PSS相关峰、系统帧头、本地帧头和本地帧尾的示意图，如图4所示，PSS相关峰与系统帧头之间的第一时域位置差值t0，PSS相关峰与DAS近端设备的本地帧尾之间的第二时域位置差值t1；若第一时域位置差值t0与第二时域位置差值t1的差值之和t’等于预设的时间长度，则DAS近端设备可以确定本地帧头与系统帧头对齐；若第一时域位置差值t0与第二时域位置差值t1的差值之和t’不等于预设的时间长度，则DAS近端设备可以根据差值之和t’与时间长度之间的差值t2，调整本地帧头的位置，从而使得本地帧头与系统帧头对齐。
应理解，本申请实施例中的第一时域位置差值、第二时域位置差值，以及预设的时间长度均可以 通过数据点数来表示。
本申请实施例中，通过根据晶振偏移量对DAS近端设备的晶振参数进行频率同步的方式，可以有效地减小收发两端由于晶振差异产生的频偏。另外，通过根据第一时域位置差值和第二时域位置差值进行时间同步的方式，可以实现低复杂度的帧同步。
在其中一个实施例中，图5为本申请另一个实施例中时频同步方法的流程示意图，在上述实施例的基础上，本申请实施例中对上述步骤S204中对于确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值的相关内容进行介绍，如图5所示，本申请实施例的方法可以包括以下步骤：
步骤S501、根据第一频域信号和信道估计矩阵进行信道均衡处理，得到第二频域信号。
本步骤中，DAS近端设备可以根据第一频域信号和信道估计矩阵，采用均衡算法进行信道均衡处理，得到第二频域信号，使得处理得到的第二频域信号更加接近信号发送端所发送的初始信号；其中，均衡算法可以包括：(Zero Forcing，ZF)均衡算法、最小均方误差(Minimum Mean Square Error，MMSE)，或者最大似然序列估计(Maximum Likelihood Sequence Estimation，MLSE)。
当然，DAS近端设备根据第一频域信号和信道估计矩阵，还可以采用其它均衡算法进行信道均衡处理，本申请实施例中对此并不作限定。
需要说明的是，DAS近端设备根据第一频域信号和信道估计矩阵进行信道均衡处理，还可以得到第一频域信号的信噪比。
若信噪比小于预设的信噪比阈值，则DAS近端设备可以从SSB索引库中更新SSB索引，并返回执行上述步骤S202中根据第一频域信号和更新后的SSB索引，确定DMRS估计频偏和信道估计矩阵的步骤。应理解，更新SSB索引是指从SSB索引库中重新确定一个SSB索引。
若信噪比大于或等于信噪比阈值，则DAS近端设备可以执行下述步骤S502中根据第二频域信号确定帧信息的步骤。
步骤S502、根据第二频域信号确定帧信息。
本步骤中，DAS近端设备可以根据第二频域信号确定帧信息；其中，帧信息可以包括系统帧信息和半帧指示信息，系统帧信息用于指示用于传输SSB信号的资源(或者称之为SSB信号)对应的系统帧号(System Frame Number，SFN)，半帧指示信息用于指示SSB信号位于系统帧的前半帧还是后半帧；当然，帧信息还可以包括其它信息，本申请实施例中对此并不作限定。
可选地，DAS近端设备对第二频域信号进行译码，得到MIB信息和物理层信息，并根据MIB信息和物理层信息，获取帧信息。
图6为本申请实施例提供的PBCH处理流程的示意图，如图6所示，信号发送端根据广播控制信道(Broadcast Control Channel，BCCH)-BCH信息和PBCH时间参数得到PBCH有效载荷。进一步地，信号发送端对PBCH有效载荷依次进行交织、第一次加扰、循环冗余校验码(Cyclic Redundancy Check，CRC)附加、Polar编码、速率匹配、二次加扰、解正交相移键控(Quadrature Phase Shift Keying，QPSK)调制和资源映射等处理得到SSB信号，然后进行SSB信号传输。
本申请实施例中，DAS近端设备通过对第二频域信号进行相应的译码处理，得到MIB信息和物理层信息，其中，译码处理包括但不限于以下至少一项：PBCH的解码、解扰、QPSK调制、解速率匹配、解Polar码、解CRC。
进一步地，MIB信息中可以包含系统帧号的部分信息，物理层信息中可以包含半帧指示信息，以及系统帧号的另一部分信息，因此，DAS近端设备可以根据MIB信息和物理层信息确定系统帧信息，以及根据物理层信息确定半帧指示信息。
当然，DAS近端设备根据MIB信息和物理层信息还可以确定其它信息，本申请实施例中对此并不作限定。
进一步地，若对第二频域信号进行译码时出现错误，则DAS近端设备可以从SSB索引库中更新SSB索引，并返回执行上述步骤S202中根据第一频域信号和更新后的SSB索引，确定DMRS估计频偏和信道估计矩阵的步骤。
需要说明的是，若SSB索引库中的所有SSB索引更新后在对第二频域信号进行译码时仍出现错误(即遍历SSB索引库中的所有SSB索引在对第二频域信号进行译码时均出现错误)，则DAS近端设备可以更新盲频偏补偿值，并返回执行上述步骤S203中根据DMRS估计频偏和更新后的盲频偏补偿值，确定晶振偏移量的步骤。
步骤S503、根据SSB图样、SSB索引和帧信息，确定第一时域位置差值。
本步骤中，DAS近端设备可以根据SSB图样(pattern)、上述步骤S201中确定的SSB索引，以及上述步骤S502中确定的帧信息，确定PSS相关峰与系统帧头之间的第一时域位置差值，其中，SSB图样可以为DAS近端设备根据第一射频信号对应的载波频段确定的。
示例性地，DAS近端设备可以根据第一射频信号对应的载波频段查询预设载波频段与SSB图样之间的对应关系，确定与第一射频信号的载波频段对应的SSB图样，其中，预设载波频段与SSB图样之间的对应关系用于指示不同载波频段与对应的SSB图样之间的关系。
可选地，DAS近端设备根据SSB图样、SSB索引和帧信息，确定SSB信号的时域信息，并根据SSB信号的时域信息，确定第一时域位置差值，其中，时域信息包括SSB信号对应的时隙和符号。
本申请实施例中的SSB图样用于指示SSB信号在时域上的分布位置，SSB索引用于指示SSB信号在半帧内的符号位置。示例性地，本申请实施例中的符号可以为OFDM符号。
本申请实施例中，DAS近端设备可以根据帧信息可以确定SSB信号所位于的系统帧信息以及半帧指示信息，并根据SSB图样和SSB索引可以确定在上述系统帧信息和半帧指示信息所指示的时域位置中的SSB信号对应的时隙和符号。
图7为本申请实施例提供的SSB图样的示意图，为了便于理解，图7中以子载波间隔为15KHz，SSB图样为CaseA为例示出。如图7所示，假设SSB图样为CaseA和SSB索引i SSB为0，则DAS近端设备根据SSB图样和SSB索引可以确定SSB信号位于子帧0(即在时域上的时隙为时隙0)，以及在时域上的符号包括第三个符号到第六个符号。应理解，当子载波间隔为15KHz时，一个系统帧包括10个子帧，一个子帧等于一个时隙，一个时隙包括14个OFDM符号。
进一步地，考虑到PSS相关峰的位置可以指示对应的SSB信号的位置，DAS近端设备可以根据SSB信号对应的时隙和符号，便可确定SSB信号与系统帧头之间的第一时域位置差值，即PSS相关峰与系统帧头之间的第一时域位置差值。
本申请实施例中，DAS近端设备通过根据第一频域信号和信道估计矩阵进行信道均衡处理，得到第二频域信号，并根据第二频域信号确定帧信息。进一步地，DAS近端设备根据SSB图样、SSB索引和帧信息，确定PSS相关峰与系统帧头之间的第一时域位置差值，以便于DAS近端设备可以根据第一时域位置差值进行时间同步。
在其中一个实施例中，图8为本申请另一个实施例中时频同步方法的流程示意图，在上述实施例的基础上，本申请实施例中对上述步骤S201中对于确定第一频域信号的相关内容进行介绍，如图8所示，本申请实施例的方法可以包括以下步骤：
步骤S801、将载波频段中的目标频点数据进行降频处理，并根据降频后的频点数据确定候选SSB信号。
本步骤中，DAS近端设备可以将载波频段中的目标频点数据进行降频处理，其中，目标频点数据可以为载波频段中选择的一个候选SSB频点数据，或者可以为载波频段中选择的一个频点数据。
可选地，DAS近端设备可以将目标频点数据进行降频处理，实现了将目标频点数据搬到零频，以便于可以减小采样频率，从而可以降低所需处理的数据量。例如，本申请实施例通过降频处理的方式，可以从122.88M采样频率降采至7.68M，对应地可以从4096个采样数据降采至256个采样数据，从而可以降低所需处理的采用数据的数量。
进一步地，DAS近端设备可以通过对降频处理所得到的降频后的频点数据进行滤波处理，以便于可以将位于零频的预设范围内的频点数据确定为候选SSB信号。
应理解，在上述步骤S204中根据第一频域信号和信道估计矩阵，确定出PSS相关峰与系统帧头之 间的第一时域位置差值之后，DAS近端设备便可以将候选SSB信号确定为SSB信号。
步骤S802、根据候选SSB信号和本地的PSS序列，确定目标PSS信号。
本申请实施例中，DAS近端设备中可以预设有多组(例如，3组)本地的PSS序列，其中，每组本地的PSS序列对应一个小区组内标识ID，不同组PSS序列对应的小区组内标识不同。例如，DAS近端设备中可以预设有本地的PSS序列0、本地的PSS序列1和本地的PSS序列2，其中，本地的PSS序列0对应小区组内标识ID0、本地的PSS序列1对应小区组内标识ID1，以及本地的PSS序列2对应小区组内标识ID2。
本步骤中，DAS近端设备可以根据候选SSB信号和本地的PSS序列进行相关峰滑动处理，以将候选SSB信号中与本地的PSS序列之间的相关峰幅度超过第一预设阈值的信号确定为目标PSS信号。应理解，候选SSB信号与本地的PSS序列会在同步点产生相关峰。
例如，假设候选SSB信号与本地的PSS序列0之间的相关峰幅度超过第一预设阈值，则DAS近端设备可以将候选SSB信号中与本地的PSS序列0之间的相关峰幅度超过第一预设阈值的信号确定为目标PSS信号。
示例性地，DAS近端设备可以采用局部峰均比算法进行相关峰滑动处理，当然，还可以采用其它算法进行相关峰滑动处理，本申请实施例中对此并不作限定。
进一步地，DAS近端设备在确定目标PSS信号之后，还可以确定目标PSS信号对应的小区组内标识，以便于DAS近端设备可以确定小区标识。
例如，假设候选SSB信号与本地的PSS序列0之间的相关峰幅度超过第一预设阈值，则DAS近端设备可以将本地的PSS序列0对应的小区组内标识ID0确定为目标PSS信号对应的小区组内标识。
步骤S803、根据盲频偏补偿值对候选SSB信号中位于目标PSS信号之后的信号进行补偿，得到补偿后的信号。
本步骤中，DAS近端设备可以根据盲频偏补偿值对候选SSB信号中位于目标PSS信号之后的信号进行盲频偏补偿处理，得到补偿后的信号，其中，盲频偏补偿值可以为DAS近端设备从预设盲频偏补偿值集合中选择的盲频偏补偿值。
步骤S804、对补偿后的信号进行频域变换，得到第一频域信号。
本步骤中，DAS近端设备可以对上述步骤S803中得到的补偿后的信号进行频域变换处理，得到第一频域信号，以便于DAS近端设备可以根据第一频域信号确定晶振偏移量以及PSS相关峰与系统帧头之间的第一时域位置差值。
本申请实施例中，通过根据载波频段中的目标频点数据降频处理所得到的降频后的频点数据确定候选SSB信号，并根据候选SSB信号和本地的PSS序列，确定目标PSS信号。进一步地，根据盲频偏补偿值对候选SSB信号中位于目标PSS信号之后的信号进行补偿，得到补偿后的信号，并对补偿后的信号进行频域变换得到第一频域信号，以便于DAS近端设备可以根据第一频域信号确定晶振偏移量以及PSS相关峰与系统帧头之间的第一时域位置差值，从而可以根据晶振偏移量和第一时域位置差值进行时频同步处理。
进一步地，在上述实施例的基础上，DAS近端设备还可以根据第一频域信号和本地的SSS序列，确定小区组标识，并根据小区组标识和目标PSS信号对应的小区组内标识，确定小区标识。
本申请实施例中，DAS近端设备中可以预设有多组(例如，336组)本地的SSS序列，其中，每组本地的SSS序列对应一个小区组标识，不同组SSS序列对应的小区组标识不同。例如，DAS近端设备中可以预设有本地的SSS序列0、本地的SSS序列1、……、本地的SSS序列335，其中，本地的SSS序列0对应小区组标识ID0、本地的SSS序列1对应小区组标识ID1、……，以及本地的SSS序列335对应小区组标识ID335。
本申请实施例中，DAS近端设备可以根据第一频域信号和本地的SSS序列进行相关峰滑动处理，以将第一频域信号中与本地的SSS序列之间的相关峰幅度超过第二预设阈值的信号确定为目标SSS信号，并确定目标SSS信号对应的小区组标识。应理解，第一频域信号与本地的SSS序列会在同步点产生相关峰。
例如，假设第一频域信号与本地的SSS序列150之间的相关峰幅度超过第二预设阈值，则DAS近端设备可以将第一频域信号中与本地的SSS序列150之间的相关峰幅度超过第二预设阈值的信号确定为目标SSS信号，并将本地的SSS序列150对应的小区组ID150确定为目标SSS信号对应的小区组标识。
进一步地，DAS近端设备可以根据目标SSS信号对应的小区组标识和目标PSS信号对应的小区组内标识，确定小区标识，其中，小区标识用于信道估计和/或译码。需要说明的是，DAS近端设备在进行信道估计时可以根据小区标识确定第一频域信号中所携带的初始DMRS序列，以便于与本地生成的DMRS序列进行信道估计。
在其中一个实施例中，图9为本申请另一个实施例中时频同步方法的流程示意图，在上述实施例的基础上，本申请实施例中结合上述实施例对时频同步方法的整体流程进行介绍，如图9所示，本申请实施例的方法可以包括以下步骤：
步骤S901、根据DAS近端设备接收到的信号对应的载波频段，遍历该载波频段中的目标频点数据。
其中，目标频点数据可以为载波频段中选择的一个候选SSB频点数据，或者可以为载波频段中选择的一个频点数据。
步骤S902、将目标频点数据进行降频处理，并通过对降频处理所得到的降频后的频点数据进行滤波处理，得到候选SSB信号。
步骤S903、根据候选SSB信号和本地的PSS序列，确定目标PSS信号以及目标PSS信号对应的小区组内标识。
步骤S904、根据盲频偏补偿值对候选SSB信号中位于目标PSS信号之后的信号进行补偿，得到补偿后的信号。
其中，盲频偏补偿值可以为DAS近端设备从预设盲频偏补偿值集合中选择的盲频偏补偿值。
步骤S905、对补偿后的信号进行频域变换，得到第一频域信号。
步骤S906、根据第一频域信号和本地的SSS序列，确定小区组标识，并根据小区组标识和目标PSS信号对应的小区组内标识，确定小区标识。
步骤S907、遍历SSB索引库中的SSB索引，并根据当前选择的SSB索引确定DMRS序列。
其中，SSB索引库为根据第一射频信号应的载波频段所确定的同步信号块SSB索引的最大值获取的。
步骤S908、根据DMRS序列和第一频域信号，确定信道估计矩阵，并根据信道估计矩阵确定DMRS估计频偏。
步骤S909、根据第一频域信号和信道估计矩阵进行信道均衡处理，得到第二频域信号以及第一频域信号的信噪比。
若信噪比大于或等于信噪比阈值，则执行步骤S910；若信噪比小于预设的信噪比阈值，则返回执行上述步骤S907中遍历SSB索引库中的另一个SSB索引(即更新SSB索引)，并根据当前选择的SSB索引确定DMRS序列的步骤。
步骤S910、对第二频域信号进行译码，得到MIB信息和物理层信息。
应理解，若译码成功，则可以执行步骤S911；若译码出现错误，则返回执行上述步骤S907中遍历SSB索引库中的另一个SSB索引(即更新SSB索引)，并根据当前选择的SSB索引确定DMRS序列的步骤。
需要说明的是，若遍历SSB索引库中的所有SSB索引在信道均衡处理所得到第一频域信号的信噪比均小于预设的信噪比阈值，或者对第二频域信号进行译码时均出现错误，则可以遍历预设盲频偏补偿值集合得到其中的另一个盲频偏补偿值(即更新盲频偏补偿值)，并返回执行步骤S904中根据更新后的盲频偏补偿值对候选SSB信号中位于目标PSS信号之后的信号进行补偿的步骤。
假设系统频偏比较大，根据比较小的盲频偏补偿值进行补偿之后仍然无法译码成功，从而需要增大盲频偏补偿值，直到译码成功，并可以锁定该盲频偏补偿值用于后续地盲补偿，但是当后续出现无 法译码成功时可以解除锁定。
需要说明的是，若遍历了预设盲频偏补偿值集合中的所有盲频偏补偿值在对第二频域信号进行译码时均出现错误，则可以返回执行步骤S901中遍历该载波频段中的另一个目标频点数据(即更新目标频点数据)的步骤。
步骤S911、根据MIB信息和物理层信息，获取帧信息。
其中，帧信息可以包括系统帧信息和半帧指示信息。
步骤S912、根据SSB图样、SSB索引和帧信息，确定PSS相关峰与系统帧头之间的第一时域位置差值。
其中，SSB图样可以为DAS近端设备根据第一射频信号对应的载波频段确定的。
步骤S913、根据第一时域位置差值和第二时域位置差值进行时间同步。
其中，第二时域位置差值可以为PSS相关峰与DAS近端设备的本地帧尾之间的时域位置差。
步骤S914、根据DMRS估计频偏和盲频偏补偿值，确定晶振偏移量，并根据晶振偏移量对DAS近端设备的晶振参数进行频率同步。
示例性地，本申请实施例中的上述步骤S901可以由DAS近端设备中的控制单元执行、上述步骤S902、步骤S903和步骤S913可以由DAS近端设备中的FPGA执行、上述步骤S904-步骤S912可以由DAS近端设备中的处理器执行，以及上述步骤S914中确定晶振偏移量的操作可以由处理器执行，而根据晶振偏移量对DAS近端设备的晶振参数进行频率同步的操作可以由FPGA执行。
当然，上述各步骤还可以由DAS近端设备中的其它单元执行，本申请实施例中对此并不作限定。
应理解，本申请实施例中各步骤的可实现方式，可以参考本申请上述实施例中的相关内容，此处不再赘述。
综上所述，本申请实施例中，通过根据信号对应的载波频段进行数据处理，确定出DMRS估计频偏、盲频偏补偿值和PSS相关峰与系统帧头之间的第一时域位置差值，并根据DMRS估计频偏和盲频偏补偿值确定晶振偏移量，进而根据晶振偏移量和第一时域位置差值进行时频同步处理。可见，相对于传统技术中采用硬件同步电路的方式，本申请实施例通过软件方式可以实现DAS设备在低信噪比和大频偏时准确地时频同步，不仅有利于节省DAS设备的产品成本，而且还便于后续新技术的迭代更新。
应该理解的是，虽然如上所述的各实施例所涉及的流程图中的各个步骤按照箭头的指示依次显示，但是这些步骤并不是必然按照箭头指示的顺序依次执行。除非本文中有明确的说明，这些步骤的执行并没有严格的顺序限制，这些步骤可以以其它的顺序执行。而且，如上所述的各实施例所涉及的流程图中的至少一部分步骤可以包括多个步骤或者多个阶段，这些步骤或者阶段并不必然是在同一时刻执行完成，而是可以在不同的时刻执行，这些步骤或者阶段的执行顺序也不必然是依次进行，而是可以与其它步骤或者其它步骤中的步骤或者阶段的至少一部分轮流或者交替地执行。
基于同样的发明构思，本申请实施例还提供了一种用于实现上述所涉及的时频同步方法的时频同步装置。该装置所提供的解决问题的实现方案与上述方法中所记载的实现方案相似，故下面所提供的一个或多个时频同步装置实施例中的具体限定可以参见上述实施例中对于时频同步方法的限定，在此不再赘述。
在其中一个实施例中，图10为本申请一个实施例中时频同步装置的结构示意图，如图10所示，本申请实施例提供的时频同步装置可以应用于DAS设备中，时频同步装置可以包括：第一确定模块1001、第二确定模块1002、第三确定模块1003、第四确定模块1004和同步模块1005。
其中，第一确定模块1001，用于根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
第二确定模块1002，用于根据第一频域信号和SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
第三确定模块1003，用于根据DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
第四确定模块1004，用于根据第一频域信号和信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；
同步模块1005，用于根据晶振偏移量和第一时域位置差值进行时频同步处理。
在其中一个实施例中，第四确定模块1004，包括：
均衡单元，用于根据第一频域信号和信道估计矩阵进行信道均衡处理，得到第二频域信号；
第一确定单元，用于根据第二频域信号确定帧信息；帧信息包括系统帧信息和半帧指示信息；
第二确定单元，用于根据SSB图样、SSB索引和帧信息，确定第一时域位置差值，其中，SSB图样为根据载波频段确定的。
在其中一个实施例中，第一确定单元具体用于：
对第二频域信号进行译码，得到MIB信息和物理层信息；
根据MIB信息和物理层信息，获取帧信息。
在其中一个实施例中，装置还包括：
第一更新模块，用于若对第二频域信号进行译码时出现错误，则从SSB索引库中更新SSB索引，并返回第二确定模块1002执行根据第一频域信号和更新后的SSB索引，确定DMRS估计频偏和信道估计矩阵的步骤。
在其中一个实施例中，装置还包括：
第二更新模块，用于若SSB索引库中的所有SSB索引更新后在对第二频域信号进行译码时仍出现错误，则更新盲频偏补偿值，并返回第三确定模块1003执行根据DMRS估计频偏和更新后的盲频偏补偿值，确定晶振偏移量的步骤。
在其中一个实施例中，第二确定单元具体用于：
根据SSB图样、SSB索引和帧信息，确定SSB信号的时域信息；时域信息包括SSB信号对应的时隙和符号；
根据SSB信号的时域信息，确定第一时域位置差值。
在其中一个实施例中，均衡单元还用于：根据第一频域信号和信道估计矩阵进行信道均衡处理，还得到第一频域信号的信噪比；
装置还包括：
第三更新模块，用于若信噪比小于预设的信噪比阈值，则从SSB索引库中更新SSB索引，并返回第二确定模块1002执行根据第一频域信号和更新后的SSB索引，确定DMRS估计频偏和信道估计矩阵的步骤；
若信噪比大于或等于信噪比阈值，则第一确定单元执行根据第二频域信号确定帧信息的步骤。
在其中一个实施例中，同步模块1005，包括：
第一同步单元，用于根据晶振偏移量对DAS近端设备的晶振参数进行频率同步；
第二同步单元，用于根据第一时域位置差值和第二时域位置差值进行时间同步；第二时域位置差值为PSS相关峰与DAS近端设备的本地帧尾之间的时域位置差。
在其中一个实施例中，第二同步单元具体用于：
对第一时域位置差值和第二时域位置差值求和，得到差值之和；
若差值之和与预设的时间长度一致，则确定DAS近端设备的本地帧头与系统帧头对齐；时间长度为根据系统帧的半帧长度确定的；
若差值之和与预设的时间长度不一致，则根据差值之和与时间长度之间的差值，调整本地帧头的位置。
在其中一个实施例中，第一确定模块1001具体用于：
将载波频段中的目标频点数据进行降频处理，并根据降频后的频点数据确定候选SSB信号；
根据候选SSB信号和本地的PSS序列，确定目标PSS信号；
根据盲频偏补偿值对候选SSB信号中位于目标PSS信号之后的信号进行补偿，得到补偿后的信号；
对补偿后的信号进行频域变换，得到第一频域信号。
在其中一个实施例中，装置还包括：
第五确定模块，用于根据第一频域信号和本地的SSS序列，确定小区组标识；
第六确定模块，用于根据小区组标识和目标PSS信号对应的小区组内标识，确定小区标识；小区标识用于信道估计和/或译码。
在其中一个实施例中，第二确定模块1002具体用于：
根据SSB索引确定DMRS序列；
根据DMRS序列和第一频域信号，确定信道估计矩阵；
根据信道估计矩阵确定DMRS估计频偏。
本申请实施例提供的时频同步装置可以用于执行本申请上述时频同步方法实施例中的技术方案，其实现原理和技术效果类似，此处不再赘述。上述时频同步装置中的各个模块可全部或部分通过软件、硬件及其组合来实现。上述各模块可以硬件形式内嵌于或独立于DAS设备中的处理器中，也可以以软件形式存储于DAS设备中的存储器中，以便于处理器调用执行以上各个模块对应的操作。
在其中一个实施例中，图11为本申请一个实施例中DAS设备的结构示意图，本申请实施例中的DAS设备可以包括但不限于DAS近端设备。如图11所示，该DAS设备包括通过系统总线连接的处理器、存储器和通信接口。其中，该DAS设备的处理器用于提供计算和控制能力。该DAS设备的存储器包括非易失性存储介质和内存储器。该非易失性存储介质存储有操作系统和计算机可读指令。该内存储器为非易失性存储介质中的操作系统和计算机可读指令的运行提供环境。该DAS设备的通信接口用于与外部的设备进行有线或无线方式的通信。该计算机可读指令被处理器执行时以实现本申请上述时频同步方法实施例中的技术方案，其实现原理和技术效果类似，此处不再赘述。
本领域技术人员可以理解，图11中示出的结构，仅仅是与本申请方案相关的部分结构的框图，并不构成对本申请方案所应用于其上的DAS设备的限定，具体的DAS设备可以包括比图中所示更多或更少的部件，或者组合某些部件，或者具有不同的部件布置。
在其中一个实施例中，还提供了一种DAS设备，包括存储器和处理器，存储器中存储有计算机可读指令，该处理器执行计算机可读指令时实现本申请上述时频同步方法实施例中的技术方案，其实现原理和技术效果类似，此处不再赘述。
在其中一个实施例中，提供了一种计算机可读存储介质，其上存储有计算机可读指令，计算机可读指令被处理器执行时实现本申请上述时频同步方法实施例中的技术方案，其实现原理和技术效果类似，此处不再赘述。
在其中一个实施例中，提供了一种计算机可读指令产品，包括计算机可读指令，该计算机可读指令被处理器执行时实现本申请上述时频同步方法实施例中的技术方案，其实现原理和技术效果类似，此处不再赘述。
本领域普通技术人员可以理解实现上述实施例方法中的全部或部分流程，是可以通过计算机可读指令来指令相关的硬件来完成，所述的计算机可读指令可存储于一非易失性计算机可读取存储介质中，该计算机可读指令在执行时，可包括如上述各方法的实施例的流程。其中，本申请所提供的各实施例中所使用的对存储器、数据库或其它介质的任何引用，均可包括非易失性和易失性存储器中的至少一种。非易失性存储器可包括只读存储器(read-only Memory，ROM)、磁带、软盘、闪存、光存储器、高密度嵌入式非易失性存储器、阻变存储器(ReRAM)、磁变存储器(magnetoresistive random Access memory，MRAM)、铁电存储器(ferroelectric random access memory，FRAM)、相变存储器(phase change memory，PCM)、石墨烯存储器等。易失性存储器可包括随机存取存储器(random access memory，RAM)或外部高速缓冲存储器等。作为说明而非局限，RAM可以是多种形式，比如静态随机存取存储器(static random access memory，SRAM)或动态随机存取存储器(dynamic random access memory，DRAM)等。本申请所提供的各实施例中所涉及的处理器可为通用处理器、中央处理器、图形处理器、数字信号处理器、可编程逻辑器、基于量子计算的数据处理逻辑器等，不限于此。

Claims (16)

  1. 一种时频同步方法，其特征在于，所述方法包括：
    根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
    根据所述第一频域信号和所述SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
    根据所述DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；及
    根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；
    根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理。
  2. 根据权利要求1所述的方法，其特征在于，所述根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值，包括：
    根据所述第一频域信号和所述信道估计矩阵进行信道均衡处理，得到第二频域信号；
    根据所述第二频域信号确定帧信息；所述帧信息包括系统帧信息和半帧指示信息；及
    根据同步信号块SSB图样、所述SSB索引和所述帧信息，确定所述第一时域位置差值，其中，所述SSB图样为根据所述载波频段确定的。
  3. 根据权利要求2所述的方法，其特征在于，所述根据所述第二频域信号确定帧信息，包括：
    对所述第二频域信号进行译码，得到主消息块MIB信息和物理层信息；及
    根据所述MIB信息和所述物理层信息，获取所述帧信息。
  4. 根据权利要求3所述的方法，其特征在于，所述方法还包括：
    若对所述第二频域信号进行译码时出现错误，则从SSB索引库中更新SSB索引，并返回执行根据所述第一频域信号和更新后的SSB索引，确定DMRS估计频偏和信道估计矩阵的步骤。
  5. 根据权利要求4所述的方法，其特征在于，所述方法还包括：
    若所述SSB索引库中的所有SSB索引更新后在对所述第二频域信号进行译码时仍出现错误，则更新所述盲频偏补偿值，并返回执行根据所述DMRS估计频偏和更新后的盲频偏补偿值，确定晶振偏移量的步骤。
  6. 根据权利要求2所述的方法，其特征在于，所述根据SSB图样、所述SSB索引和所述帧信息，确定所述第一时域位置差值，包括：
    根据所述SSB图样、所述SSB索引和所述帧信息，确定SSB信号的时域信息；所述时域信息包括所述SSB信号对应的时隙和符号；及
    根据所述SSB信号的时域信息，确定所述第一时域位置差值。
  7. 根据权利要求2所述的方法，其特征在于，所述方法还包括：
    根据所述第一频域信号和所述信道估计矩阵进行信道均衡处理，还得到所述第一频域信号的信噪比；
    若所述信噪比小于预设的信噪比阈值，则从SSB索引库中更新SSB索引，并返回执行根据所述第一频域信号和更新后的SSB索引，确定DMRS估计频偏和信道估计矩阵的步骤；及
    若所述信噪比大于或等于所述信噪比阈值，则执行根据所述第二频域信号，确定帧信息的步骤。
  8. 根据权利要求1-7中任一项所述的方法，其特征在于，所述根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理，包括：
    根据所述晶振偏移量对所述DAS近端设备的晶振参数进行频率同步；及
    根据所述第一时域位置差值和第二时域位置差值进行时间同步；所述第二时域位置差值为所述PSS相关峰与所述DAS近端设备的本地帧尾之间的时域位置差。
  9. 根据权利要求8所述的方法，其特征在于，所述根据所述第一时域位置差值和第二时域位置差值进行时间同步，包括：
    对所述第一时域位置差值和所述第二时域位置差值求和，得到差值之和；
    若所述差值之和与预设的时间长度一致，则确定所述DAS近端设备的本地帧头与系统帧头对齐； 所述时间长度为根据系统帧的半帧长度确定的；及
    若所述差值之和与所述预设的时间长度不一致，则根据所述差值之和与所述时间长度之间的差值，调整所述本地帧头的位置。
  10. 根据权利要求1-7中任一项所述的方法，其特征在于，所述根据DAS近端设备接收到的信号对应的载波频段，确定第一频域信号，包括：
    将所述载波频段中的目标频点数据进行降频处理，并根据降频后的频点数据确定候选SSB信号；
    根据所述候选SSB信号和本地的PSS序列，确定目标PSS信号；
    根据所述盲频偏补偿值对所述候选SSB信号中位于所述目标PSS信号之后的信号进行补偿，得到补偿后的信号；及
    对所述补偿后的信号进行频域变换，得到所述第一频域信号。
  11. 根据权利要求10所述的方法，其特征在于，还包括：
    根据所述第一频域信号和本地的SSS序列，确定小区组标识；及
    根据所述小区组标识和所述目标PSS信号对应的小区组内标识，确定小区标识；所述小区标识用于信道估计和/或译码。
  12. 根据权利要求1-7中任一项所述的方法，其特征在于，所述根据所述第一频域信号和所述SSB索引，确定DMRS估计频偏和信道估计矩阵，包括：
    根据所述SSB索引确定DMRS序列；
    根据所述DMRS序列和所述第一频域信号，确定所述信道估计矩阵；及
    根据所述信道估计矩阵确定所述DMRS估计频偏。
  13. 一种时频同步装置，其特征在于，所述装置包括：
    第一确定模块，用于根据分布式天线系统DAS近端设备接收到的信号对应的载波频段，确定第一频域信号和同步信号块SSB索引；
    第二确定模块，用于根据所述第一频域信号和所述SSB索引，确定解调参考信号DMRS估计频偏和信道估计矩阵；
    第三确定模块，用于根据所述DMRS估计频偏和盲频偏补偿值，确定晶振偏移量；
    第四确定模块，用于根据所述第一频域信号和所述信道估计矩阵，确定主同步信号PSS相关峰与系统帧头之间的第一时域位置差值；及
    同步模块，用于根据所述晶振偏移量和所述第一时域位置差值进行时频同步处理。
  14. 一种DAS设备，包括存储器及一个或多个处理器，所述存储器中储存有计算机可读指令，所述计算机可读指令被所述一个或多个处理器执行时，使得所述一个或多个处理器执行权利要求1至12中任一项所述的时频同步方法的步骤。
  15. 一个或多个存储有计算机可读指令的非易失性计算机可读存储介质，所述计算机可读指令被一个或多个处理器执行时，使得所述一个或多个处理器执行权利要求1至12中任一项所述的时频同步方法的步骤。
  16. 一种计算机可读指令产品，包括计算机可读指令，该计算机可读指令被处理器执行时实现权利要求1至12中任一项所述的时频同步方法的步骤。
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