Timing synchronization method in power line scene
Through the two-stage timing synchronization method, the thickness timing measurement combined with the symbolic characteristics of sending basic preamble signals is used to solve the problems of low timing synchronization accuracy and high complexity in power line communication, and achieve higher accuracy and lower complexity timing synchronization.
Patent Information
- Application Number
- CN202510589009.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2025-08-08
AI Technical Summary
The estimation accuracy of the timing synchronization method in existing power line communication is low and the algorithm complexity is high, so it cannot meet the synchronization accuracy requirements of OFDM systems.
Using the two-stage timing synchronization method, the fuzzy position of the leading signal is determined first through coarse timing metrics, and then the precise position is determined through fine timing metrics. The symbolic opposite characteristics of the sending basic preamble signals SYNCP and SYNCM are used to reduce the calculation complexity and improve the estimation accuracy.
While reducing the computational complexity, the estimation accuracy of timing synchronization is significantly improved, achieving higher synchronization accuracy and lower computing cost.
Smart Images
Figure CN120455227A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of wireless communication signal processing, and in particular to a timing synchronization method in a power line scenario. Background Art
[0002] Power Line Communication (PLC) is a communications technology that uses existing power lines to transmit data. Its core advantage is that it eliminates the need for laying additional communication lines and can directly utilize the extensive power network for information transmission. However, power line channels exhibit frequency-selective fading and contain colored background noise, narrowband noise, non-periodic impulse noise, periodic impulse noise synchronized with the power supply cycle, and periodic impulse noise asynchronous with the power supply cycle. For this reason, Orthogonal Frequency Division Multiplexing (OFDM) is widely adopted in PLC systems.
[0003] OFDM signals have good resistance to frequency selective fading. However, OFDM signals require high synchronization accuracy; otherwise, the orthogonality of the subcarriers cannot be guaranteed, greatly reducing the performance of the OFDM system. The pilot signal of the PLC system is designed as a repetitive structure, aiming to achieve timing synchronization through its repetitive structure. The pilot signal is a specially designed known signal that the sender embeds when transmitting data, mainly to help the receiver estimate the state and characteristics of the channel. Through the received pilot signal, the receiver can better understand and process the transmitted data, ensuring the stability and reliability of communication. Traditional timing synchronization methods in power line scenarios simply use the autocorrelation characteristics of the received pilot signal, or the cross-correlation characteristics of the received pilot signal and the local pilot signal. The timing synchronization estimation accuracy is low and the algorithm complexity is high. Summary of the Invention
[0004] The present application aims to at least solve the technical problems existing in the prior art and provide a timing synchronization method in a power line scenario.
[0005] The present invention provides a timing synchronization method in a power line scenario, comprising:
[0006] The transmitter sends a preamble signal;
[0007] The pilot signal is transmitted through the power line channel and received by the receiving end through the radio frequency link to obtain the received signal;
[0008] Calculating a coarse timing metric of the received signal according to a preset rule, and determining the ambiguous position of the preamble in the received signal using the coarse timing metric;
[0009] The fine timing metric of the received signal is calculated by the fuzzy position of the preamble in the received signal and the local preamble signal pre-stored at the receiving end, and the precise position of the preamble in the received signal is determined by the fine timing metric to achieve timing synchronization.
[0010] Optionally, the preamble signal includes several consecutive transmitted basic preamble signals SYNCP and several consecutive transmitted basic preamble signals SYNCM;
[0011] The expression for sending the basic preamble signal SYNCP is:
[0012]
[0013] Where real(·) represents the real part operation, N represents the number of inverse fast Fourier transform points, n represents the index of the inverse fast Fourier transform point, and c n represents the modulation symbol of subcarrier n, and k represents the signal time domain sampling point index;
[0014] The basic preamble signal SYNCM is:
[0015] s (SYNCM) [k]=-s (SYNCP) [k],0≤k≤N-1.
[0016] Optionally, the expression of the preamble signal in the received signal is:
[0017]
[0018] Where r[k] represents the kth received pilot signal, k represents the signal time domain sampling point index, L represents the maximum number of taps of the power line channel, and h l represents the path gain of the lth path of the power line channel, τ l represents the time delay of the lth path of the power line channel, n[k] represents the channel noise, s[k-τ l ] means delaying the kth leading signal.
[0019] Optionally, calculating a coarse timing metric of the received signal according to a preset rule, and determining an ambiguous position of the preamble in the received signal by using the coarse timing metric, includes:
[0020] Do N on the received signal down times downsampling to obtain the downsampled received signal, N down is a power of 2;
[0021] At least one basic pilot signal SYNCP and at least one basic pilot signal SYNCM are selected from the downsampled received signal to construct a coarse timing signal window. The window length of the coarse timing signal window is N preambleIndicates the number of preamble signals in the coarse timing signal window;
[0022] Sliding and calculating a coarse timing signal window to receive a coarse timing metric of the signal after downsampling;
[0023] Sort the coarse timing metrics of each signal frame in the downsampled received signal from large to small, and select the N with the largest coarse timing metric coarseMax The position corresponding to the signal frame is obtained to obtain the target coarse timing signal position, N coarseMax is a positive integer greater than 1;
[0024] The ambiguity position of the preamble in the received signal is determined according to the target coarse timing signal position.
[0025] Optionally, the expression for the coarse timing metric is:
[0026]
[0027] Among them, the number of leading signals in the coarse timing signal window is N preamble ≥2, P coarse [k] represents the autocorrelation value of the first signal and the second signal in the coarse timing signal window; P coarse The calculation formula for [k] is:
[0028]
[0029] Where m represents the index of the pilot signal in the coarse timing signal window; P sign Indicates the symbol mode of the basic preamble signal, the symbol mode of the basic preamble signal SYNCP is 1, and the symbol mode of the basic preamble signal SYNCM is -1; (·) * indicates conjugation;
[0030] E coarse The expression for [k] is:
[0031]
[0032] E coarse [k] represents the energy of the pilot signal within the coarse timing signal window.
[0033] Optionally, determining the ambiguous position of the preamble in the received signal according to the target coarse timing signal position includes:
[0034] Expand each target coarse timing signal position to 2N down -1 value to get the extended value of the target coarse timing signal position;
[0035] Integration N coarseMaxThe target coarse timing signal positions and the extended values of each target coarse timing signal position are used to obtain the fuzzy position of the preamble in the received signal. All fuzzy positions obtained by coarse timing are recorded as d coarse , the number is N coarsePos , N coarsePos ≤N coarseMax ×(2N down -1).
[0036] Optionally, calculating a fine timing metric of the received signal using an ambiguous position of the preamble in the received signal and a local preamble signal pre-stored at the receiving end, and determining a precise position of the preamble in the received signal using the fine timing metric to achieve timing synchronization includes:
[0037] The fine timing signal window is constructed based on the pilot signal selected when calculating the coarse timing metric of the received signal; the starting position of the fine timing signal window is the coarse timing ambiguity position, and the window length of the fine timing signal window is N preamble N;
[0038] The fine timing metric value of the fine timing signal window in the received signal is calculated by sliding; the precise position of the preamble in the received signal is determined from the position corresponding to the signal frame with the largest fine timing metric value in the received signal to achieve timing synchronization.
[0039] Optionally, the expression for the fine timing metric is:
[0040]
[0041] Among them, P fine [k] represents the cross-correlation between the received signal and the local pilot signal within the fine timing signal window, P fine The calculation formula for [k] is:
[0042]
[0043] Where m represents the index of the leading signal in the fine timing signal window; P sign [.] represents the symbol mode of the basic preamble signal. The symbol mode of the basic preamble signal SYNCP is 1, and the symbol mode of the basic preamble signal SYNCM is -1; s (SYNCP) [.] indicates the local preamble signal pre-stored at the receiving end, (·) * indicates conjugation;
[0044] E fine [k] represents the energy normalization factor of the fine timing signal window, E fine The expression for [k] is:
[0045]
[0046] E (SYNCP)Represents the energy of the local pilot signal pre-stored at the receiving end, E (SYNCP) The expression is:
[0047]
[0048] Optionally, the exact position of the first sampling point of the pilot signal in the received signal is:
[0049]
[0050] Among them, arg max(.) represents the maximum value operation.
[0051] In summary, this application has the following beneficial technical effects:
[0052] The timing synchronization method of the present application includes a coarse timing stage and a fine timing stage. In the coarse timing synchronization stage, a coarse timing metric of the downsampled received signal is calculated, and finally the fuzzy position of the pilot signal in the received signal is calculated using the coarse timing metric. In the fine timing synchronization stage, a fine timing metric of the received signal is first calculated using the fuzzy position of the pilot signal obtained in the coarse timing synchronization stage and the local pilot signal, and then the precise position of the pilot signal in the received signal is calculated using the fine timing metric. Compared with traditional timing synchronization methods, the present invention divides timing synchronization into two stages. The coarse synchronization stage determines the fuzzy position with lower complexity, and the fine synchronization determines the precise position, resulting in higher estimation accuracy and lower computational complexity.
[0053] The received signal is downsampled during coarse timing synchronization, which reduces the complexity of calculating the coarse timing metric; while retaining N when calculating the fuzzy position. coarseMax The maximum value position improves the accuracy of fuzzy position estimation;
[0054] During fine timing synchronization, the filtered fuzzy positions are expanded, and the fine timing measurements of all fuzzy positions are calculated. According to the coarse timing fuzzy positions, the computational complexity and the accuracy of the fine timing estimation are comprehensively considered, which can reduce the computational complexity while making the fine position of the pilot signal in the received signal more accurate; the signs of the sent basic pilot signal SYNCP and the sent basic pilot signal SYNCM are opposite. The present application utilizes the opposite sign characteristics of the sent basic pilot signal SYNCP and the sent basic pilot signal SYNCM to reduce the possibility that the coarse timing measurement trajectory (fine timing measurement estimation) has a flat trajectory, and it is easier to filter out positions with high coarse timing measurement autocorrelation (fine timing measurement autocorrelation), which can improve the timing estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0055] Figure 1 A schematic diagram of a flow chart of a timing synchronization method in a power line scenario provided by one embodiment of the present invention;
[0056] Figure 2 A block diagram of a timing synchronization algorithm provided by an embodiment of the present invention;
[0057] Figure 3 A schematic diagram of the format of a preamble signal;
[0058] Figure 4 The coarse timing measurement trajectory curves are selected when the number of basic preamble signals is 2, 3, 4, 5, and 6 without channel and noise influence;
[0059] Figure 5 : This is the accuracy curve of the timing estimation method proposed in the present invention under the four-path channel specified by the IEEE 1901.1.1(TM)-2020 protocol.
[0060] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION
[0061] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.
[0062] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.
[0063] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.
[0064] Reference Figure 1 and Figure 2 In this embodiment, the timing synchronization method in the power line scenario includes:
[0065] S1. The transmitter sends a preamble signal.
[0066] Specifically, the preamble signal is a continuous sequence of signal frames, and the receiving end pre-stores a local preamble signal locally; the format and content of the preamble signal are consistent with the local preamble signal pre-stored at the receiving end; the preamble signal is mainly used in the communication system to achieve synchronization between the sender and the receiver (including time, frequency and bit synchronization), assist the receiving end in quickly detecting the signal and optimizing the gain control, and at the same time complete preliminary channel estimation through the training sequence, identify the starting position of the data frame and transmit key information such as modulation parameters, thereby ensuring efficient coordination and stable and reliable communication links.
[0067] The pilot signal includes several consecutive basic pilot signals SYNCP (hereinafter referred to as SYNCP) and several consecutive basic pilot signals SYNCM (hereinafter referred to as SYNCM). In this embodiment, the pilot signal is composed of 10.5 basic pilot signals SYNCP and 2.5 basic pilot signals SYNCM. The pilot signal is recorded as: s[k], 0≤k≤13N-1, k represents the signal time domain sampling point index, N represents the frequency domain subcarrier point number, and in this embodiment, N is 1024. The format of the pilot signal is as follows: Figure 3 As shown in Figure 1, 0.5 SYNCPs are located at the very beginning of the preamble signal, and 0.5 SYNCMs are located at the very end of the preamble signal. The first 0.5 SYNCPs of the preamble signal are the second half of the entire SYNCP, and the last 0.5 SYNCMs are the first half of the entire SYNCM. The 10 complete SYNCPs are denoted as SYNCP0 to SYNCP9, and the two complete SYNCMs are denoted as SYNCM0 and SYNCM1.
[0068] At the Nyquist sampling rate, the expression for sending the basic preamble signal SYNCP is:
[0069] The expression for sending the basic preamble signal SYNCP is:
[0070]
[0071] Where real(·) represents the real part operation, N represents the number of inverse fast Fourier transform points, n represents the index of the inverse fast Fourier transform point, and c n represents the modulation symbol of subcarrier n, and k represents the signal time domain sampling point index;
[0072] The basic preamble signal SYNCM is:
[0073] s (SYNCM) [k]=-s (SYNCP) [k],0≤k≤N-1.
[0074] The signs of the basic preamble signal SYNCP and the basic preamble signal SYNCM are opposite. The symbol pattern of the basic preamble signal SYNCP is 1, and the symbol pattern of the basic preamble signal SYNCM is -1.
[0075] S2. The pilot signal is transmitted through the power line channel and received by the receiving end through the radio frequency link to obtain the received signal.
[0076] Specifically, the receiving end receives a receiving signal through a radio frequency link. The receiving signal includes a noise signal, a valid signal, and a pilot signal located in front of the valid signal. Timing synchronization is achieved by locating the pilot signal in the receiving signal.
[0077] The expression of the leading signal in the received signal is:
[0078]
[0079] Where r[k] represents the kth received pilot signal, k represents the signal time domain sampling point index. In this embodiment, the value of k is a positive integer. Since the receiving end continuously receives external signals, there is no specific range for the value of k here. L represents the maximum number of taps of the power line channel, h l represents the path gain of the lth path of the power line channel, τ l represents the time delay of the lth path of the power line channel, and n[k] represents the channel noise;
[0080] It should be noted that, in the transmitted signal and the received signal, k is only used to represent the position of the sampling point in the signal waveform corresponding to the analog signal, that is, to represent the signal at a certain sampling point. The value of k in the transmitted signal and the value of k in the received signal are not corresponding.
[0081] s[k-τ l ] indicates that the kth preamble signal is delayed. Without loss of generality, assume that 0≤τ0<τ1<…<τ L , and |h0|>|h1|>…>|h L |. τ L It is called the maximum delay spread of the channel. The essence of timing synchronization is to estimate the minimum delay τ0 of the pilot signal; or it can be described as finding the starting position d of timing synchronization based on τ0. sync (Range d sync ≤k≤d sync The received signal in +13N-1 contains all the information of the preamble).
[0082] S3. Calculate a coarse timing metric of the received signal according to a preset rule, and determine the ambiguous position of the preamble in the received signal through the coarse timing metric.
[0083] Specifically, a coarse timing metric of the received signal is calculated according to a preset rule, and the ambiguous position of the preamble in the received signal is determined by the coarse timing metric, including:
[0084] S31, do N to the received signal down The down-sampled signal is obtained by downsampling.
[0085] N down Usually a power of 2; the expression of the received signal after downsampling is
[0086] r (down) [k]=r[N down k], k=0,1,…,
[0087] By reducing the number of data points to reduce the resolution or frequency of the signal, downsampling can effectively reduce the amount of data, increase processing speed, and adapt to specific hardware requirements.
[0088] S32: Select at least one basic pilot signal SYNCP and at least one basic pilot signal SYNCM from the downsampled received signal to construct a coarse timing signal window.
[0089] The window length of the coarse timing signal window is N preamble represents the number of leading signals in the coarse timing signal window, and “·” represents a multiplication operation.
[0090] Specifically, a portion of SYNCP or SYNCM in the downsampled received signal is selected to calculate the coarse timing metric. The selection criteria should ensure that the coarse timing metric trajectory has a steep roll-off characteristic. Since the signs of SYNCM and SYNCP are opposite, in order to avoid the coarse timing metric trajectory having a flat trajectory, SYNCP and SYNCM should be selected at the same time. Assume that the number of basic preamble symbols selected is N preamble , the symbol pattern of the basic pilot signal is p sign , the symbol mode of SYNCP is 1, the symbol mode of SYNCM is -1, N preamble Indicates the number of basic preamble signals in the first target basic preamble signal data set.
[0091] S33 , slidingly calculating a coarse timing metric of the received signal after downsampling the coarse timing signal window.
[0092] In this embodiment, the coarse timing metric is the normalized autocorrelation between the first pilot signal and the second pilot signal within the coarse timing signal window. The expression of the coarse timing metric is:
[0093]
[0094] Among them, the number of leading signals in the coarse timing signal window is N preamble ≥2, Pcoarse [k] represents the autocorrelation value of the first signal and the second signal in the coarse timing signal window; P coarse The calculation formula for [k] is:
[0095]
[0096] Where m represents the index of the pilot signal in the coarse timing signal window; P sign Indicates the symbol pattern of the basic preamble signal, P sign The following [m] represents the index of the pilot signal within the fine timing signal window; the symbol pattern of the basic pilot signal SYNCP is 1, and the symbol pattern of the basic pilot signal SYNCM is -1; (·) * indicates conjugation;
[0097] E coarse The expression for [k] is:
[0098]
[0099] E coarse [k] represents the energy of the pilot signal within the coarse timing signal window.
[0100] Figure 4 The number of basic pilot signals N selected without channel and noise influence is given preamble The rough timing measurement trajectory curves are 2, 3, 4, 5, and 6. Figure 4 It can be seen that the coarse timing metric trajectory curve performance is best when the number of basic pilots selected is 4 and the symbol pattern of the basic pilot signal is [1, 1, -1, -1] (two SYNCPs and two SYNCMs are selected); in the preferred implementation of this embodiment, SYNCP8, SYNCP9, SYNCM0 and SYNCM1 in the downsampled received signal are selected to calculate the coarse timing metric. Since SYNCM is the inverse of SYNCP, the symbol pattern of these four basic pilot signals is p sign =[1,1,-1,-1].
[0101] S34, sorting the coarse timing metrics of each signal frame in the downsampled received signal from large to small, and selecting the N frame with the largest coarse timing metric coarseMax The position corresponding to the signal frame is obtained to obtain the target coarse timing signal position, N coarseMax is a positive integer greater than 1.
[0102] The coarse timing metric M of each signal frame in the downsampled received signal coarse [k] Sort from large to small, select N from large to small coarseMax coarse timing metric, the above N coarseMax The position p corresponding to the coarse timing metriccoarse [0],p coarse [1],…,p coarse [N coarseMax -1] is the target coarse timing signal position, p coarse [.] indicates the position of the signal time domain sampling point.
[0103] S35. Determine the ambiguous position of the preamble in the received signal according to the target coarse timing signal position.
[0104] Determining the ambiguous position of the preamble in the received signal according to the target coarse timing signal position includes:
[0105] S351, expand each target coarse timing signal position to 2N down -1 value to get the extended value of the target coarse timing signal position;
[0106] S352, Integration N coarseMax The fuzzy position of the preamble in the received signal is obtained by calculating the target coarse timing signal positions and the extension value of each target coarse timing signal position.
[0107] Since N is done on the received signal down times downsampling, each position needs to be expanded to 2N down -1 value. In order to facilitate the understanding of those skilled in the art, the following is an explanation of the location expansion process with reference to a specific example: coarse [0] as an example, the fuzzy position of the first sampling point of SYNCP8 after expansion is N down p coarse [0]+k,-(N down -1)≤k≤N down -1; when N down When the value is 8, the received signal is downsampled 8 times, and the fuzzy position of the first sampling point of SYNCP8 is d1, then the value of p coarse [0] After the position is expanded, the expanded value is d1-7, ..., d1-1, d1, d1+1, ..., d1+7; after all positions are expanded, there may be repetitions of the coarse timing fuzzy position, and the repeated position is only taken once. All the fuzzy positions obtained by coarse timing are recorded as d coarse , the number is N coarsePos , obviously there are: N coarsePos ≤N coarseMax ×(2N down -1), the equality holds if and only if there is no duplication in the coarse timing fuzzy positions after all positions are expanded.
[0108] All fuzzy positions obtained by coarse timing are denoted as d coarse , the number is N coarsePos , obviously there are: N coarsePos≤N coarseMax ×(2N down -1), the equality holds if and only if there is no duplication in the coarse timing fuzzy positions after all positions are expanded.
[0109] S4. Calculate the fine timing metric of the received signal using the fuzzy position of the preamble in the received signal and the local preamble signal pre-stored at the receiving end, and determine the precise position of the preamble in the received signal using the fine timing metric to achieve timing synchronization.
[0110] The precise location of the preamble in the received signal refers to the starting time point and duration range of the preamble in the signal stream determined by the receiving end through synchronization technology.
[0111] Specifically, a fine timing metric of the received signal is calculated using the ambiguous position of the preamble in the received signal and a local preamble signal pre-stored at the receiving end, and the precise position of the preamble in the received signal is determined using the fine timing metric to achieve timing synchronization, including:
[0112] S41 . Construct a fine timing signal window according to the pilot signal selected when calculating the coarse timing metric of the received signal.
[0113] Specifically, the starting position of the fine timing signal window is the coarse timing ambiguity position, and the window length of the fine timing signal window is N preamble ·N.
[0114] S42: Slidingly calculate the fine timing metric value of the fine timing signal window in the received signal.
[0115] In a preferred embodiment of this embodiment, the fine timing metric of the received signal is calculated using the coarse timing ambiguity position of the first sampling point of SYNCP8 during the coarse timing synchronization phase and the local pilot signal. Based on the coarse timing ambiguity position, and taking into account both computational complexity and the accuracy of the fine timing estimation, the normalized cross-correlation between SYNCP8, SYNCP9, SYNCM0, and SYNCM1 in the received signal and the local pilot signal SYNCP is calculated.
[0116] The expression for the fine timing metric is:
[0117]
[0118] Among them, P fine [k] represents the cross-correlation between the received signal and the local pilot signal within the fine timing signal window, P fine The calculation formula for [k] is:
[0119]
[0120] Where m represents the index of the leading signal in the fine timing signal window; P sign Indicates the symbol pattern of the basic preamble signal, Psign The following [m] represents the index of the pilot signal in the fine timing signal window. The symbol pattern of the basic pilot signal SYNCP is 1, and the symbol pattern of the basic pilot signal SYNCM is -1. (SYNCP) Indicates the local pilot signal pre-stored at the receiving end, s (SYNCP) The following [n] represents the index of the inverse fast Fourier transform point of the local pilot signal, (·) * indicates conjugation;
[0121] E fine [k] represents the energy normalization factor of the fine timing signal window, E fine The expression for [k] is:
[0122]
[0123] E (SYNCP) Represents the energy of the local pilot signal pre-stored at the receiving end, E (SYNCP) The expression is:
[0124]
[0125] S43 . Determine the precise position of the preamble in the received signal from the position corresponding to the signal frame having the largest fine timing metric value in the received signal, so as to achieve timing synchronization.
[0126] Specifically, the maximum position of the fine timing metric is selected, i.e., the exact position of the first sampling point of SYNCP8 in the received signal;
[0127] The exact position of the first sampling point of the pilot signal in the received signal is:
[0128]
[0129] Among them, arg max(.) represents the maximum value operation.
[0130] like Figure 5 As shown in FIG, under the 4-path channel specified by the IEEE 1901.1.1(TM)-2020 protocol, the timing estimation method proposed in the present invention has an accuracy curve. Figure 5 It can be seen from FIG1 that as the SNR increases, the preamble starting position estimated by the timing estimation method proposed in the present invention converges to the actual preamble starting position.
[0131] The timing synchronization method in the power line scenario disclosed in the present application can be loaded in an electronic device. The electronic device may include at least one processor, a memory connected to the at least one processor for communication, a communication bus, and a communication interface. It may also include a computer program stored in the memory and executable on the processor, such as a method program for timing synchronization in the power line scenario.
[0132] In some embodiments, the processor may be composed of an integrated circuit, for example, a single packaged integrated circuit, or a plurality of packaged integrated circuits with the same or different functions, including one or more central processing units (CPUs), microprocessors, digital processing chips, graphics processors, and a combination of various control chips. The processor is the control core (Control Unit) of the electronic device, connecting the various components of the entire electronic device using various interfaces and lines, and executing or executing programs or modules stored in the memory (for example, a method for executing timing synchronization in a power line scenario, etc.), as well as calling data stored in the memory, to execute various functions of the electronic device and process data.
[0133] The memory includes at least one type of readable storage medium, and the readable storage medium includes a flash memory, a mobile hard disk, a multimedia card, a card-type memory (for example, an SD or DX memory, etc.), a magnetic memory, a disk, an optical disk, etc. In some embodiments, the memory may be an internal storage unit of an electronic device, such as a mobile hard disk of the electronic device. In other embodiments, the memory may also be an external storage device of an electronic device, such as a plug-in mobile hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device. Furthermore, the memory may also include both an internal storage unit and an external storage device of the electronic device. The memory can not only be used to store application software and various types of data installed in the electronic device, such as the code of the method program for timing synchronization in a power line scenario, but can also be used to temporarily store data that has been output or is to be output.
[0134] The communication bus may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus may be divided into an address bus, a data bus, a control bus, etc. The bus is configured to enable communication between the memory and at least one processor.
[0135] The communication interface is used for communication between the above-mentioned electronic device and other devices, including a network interface and a user interface. Optionally, the network interface may include a wired interface and / or a wireless interface (such as a WI-FI interface, a Bluetooth interface, etc.), which is generally used to establish a communication connection between the electronic device and other electronic devices. The user interface may be a display (Display), an input unit (such as a keyboard (Keyboard)), optionally, the user interface may also be a standard wired interface, a wireless interface. Optionally, in some embodiments, the display may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, and an OLED (Organic Light-Emitting Diode, organic light-emitting diode) touch device, etc. Among them, the display may also be appropriately referred to as a display screen or a display unit, for displaying information processed in the electronic device and for displaying a visual user interface.
[0136] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "example," "specific example," "one implementation," "a preferred implementation," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
[0137] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.
Claims
1. A timing synchronization method in a power line scenario, characterized in that: The method comprises: The transmitter sends a preamble signal; The pilot signal is transmitted through the power line channel and received by the receiving end through the radio frequency link to obtain the received signal; Calculating a coarse timing metric of the received signal according to a preset rule, and determining the ambiguous position of the preamble in the received signal using the coarse timing metric; The fine timing metric of the received signal is calculated by the fuzzy position of the preamble in the received signal and the local preamble signal pre-stored at the receiving end, and the precise position of the preamble in the received signal is determined by the fine timing metric to achieve timing synchronization.
2. The timing synchronization method in the power line scenario according to claim 1, characterized in that , the preamble signal includes several consecutive transmitted basic preamble signals SYNCP and several consecutive transmitted basic preamble signals SYNCM; The expression for sending the basic preamble signal SYNCP is: Where real(·) represents the real part operation, N represents the number of inverse fast Fourier transform points, n represents the index of the inverse fast Fourier transform point, and c n represents the modulation symbol of subcarrier n, and k represents the signal time domain sampling point index; The basic preamble signal SYNCM is: s (SYNCM) [k]=-s (SYNCP) [k],0≤k≤N-1。 3. The timing synchronization method in the power line scenario according to claim 1, characterized in that ,The expression of the leading signal in the received signal is: Where r[k] represents the kth received pilot signal, k represents the signal time domain sampling point index, L represents the maximum number of taps of the power line channel, h l represents the path gain of the lth path of the power line channel, τ l represents the time delay of the lth path of the power line channel, n[k] represents the channel noise, s[k-τ l ] means delaying the kth leading signal.
4. The timing synchronization method in the power line scenario according to claim 2, characterized in that , the calculating of the coarse timing metric of the received signal according to a preset rule, and determining the fuzzy position of the preamble in the received signal by the coarse timing metric, includes: Do N on the received signal down times downsampling to obtain the downsampled received signal, N down is a power of 2; At least one basic pilot signal SYNCP and at least one basic pilot signal SYNCM are selected from the downsampled received signal to construct a coarse timing signal window. The window length of the coarse timing signal window is N preamble Indicates the number of preamble signals in the coarse timing signal window; Sliding and calculating a coarse timing signal window to receive a coarse timing metric of the signal after downsampling; Sort the coarse timing metrics of each signal frame in the downsampled received signal from large to small, and select the N with the largest coarse timing metric coarseMax The position corresponding to the signal frame is obtained to obtain the target coarse timing signal position, N coarseMax is a positive integer greater than 1; The ambiguity position of the preamble in the received signal is determined according to the target coarse timing signal position.
5. The timing synchronization method in the power line scenario according to claim 4, characterized in that , The expression for the coarse timing metric is: Among them, the number of leading signals in the coarse timing signal window is N preamble ≥2, P coarse [k] represents the autocorrelation value of the first signal and the second signal in the coarse timing signal window; P coarse The calculation formula for [k] is: Where m represents the index of the pilot signal in the coarse timing signal window; P sign Indicates the symbol mode of the basic preamble signal, the symbol mode of the basic preamble signal SYNCP is 1, and the symbol mode of the basic preamble signal SYNCM is -1; (·) * indicates conjugation; E coarse The expression for [k] is: E coarse [k] represents the energy of the pilot signal within the coarse timing signal window.
6. The timing synchronization method in a power line scenario according to claim 4 or 5, characterized in that: Determining the ambiguous position of the preamble in the received signal according to the target coarse timing signal position includes: Expand each target coarse timing signal position to 2N down -1 value to get the extended value of the target coarse timing signal position; Integration N coarseMax The target coarse timing signal positions and the extended values of each target coarse timing signal position are used to obtain the fuzzy position of the preamble in the received signal. All fuzzy positions obtained by coarse timing are recorded as d coarse , the number is recorded as N coarsePos , N coarsePos ≤N coarseMax ×(2N down -1).
7. The timing synchronization method in a power line scenario according to claim 4, characterized in that: The method of calculating a fine timing metric of the received signal using the ambiguous position of the preamble in the received signal and a local preamble signal pre-stored at the receiving end, and determining the precise position of the preamble in the received signal using the fine timing metric to achieve timing synchronization includes: The fine timing signal window is constructed based on the pilot signal selected when calculating the coarse timing metric of the received signal; the starting position of the fine timing signal window is the coarse timing ambiguity position, and the window length of the fine timing signal window is N preamble N; Sliding and calculating a fine timing metric value of a fine timing signal window in a received signal; The precise position of the preamble in the received signal is determined from the position corresponding to the signal frame with the largest fine timing metric value in the received signal to achieve timing synchronization.
8. The timing synchronization method in a power line scenario according to claim 7, characterized in that: The expression for the fine timing metric is: Among them, P fine [k] represents the cross-correlation between the received signal and the local pilot signal within the fine timing signal window, P fine The calculation formula for [k] is: Where m represents the index of the leading signal in the fine timing signal window; P sign Indicates the symbol mode of the basic preamble signal. The symbol mode of the basic preamble signal SYNCP is 1, and the symbol mode of the basic preamble signal SYNCM is -1. (SYNCP) Represents the local pilot signal pre-stored at the receiving end, (·) * indicates conjugation; E fine [k] represents the energy normalization factor of the fine timing signal window, E fine The expression for [k] is: E (SYNCP) Represents the energy of the local pilot signal pre-stored at the receiving end, E (SYNCP) The expression is:
9. The timing synchronization method in a power line scenario according to claim 8, characterized in that: The exact position of the first sampling point of the pilot signal in the received signal is: Among them, arg max(.) represents the maximum value operation.