An electric energy meter reading system and method based on the Internet of Things

Abstract

The application relates to the technical field of multi-path data transmission, and discloses an electric energy meter reading system and method based on the Internet of Things, which comprises the following steps: dividing a target electric energy meter into a meter reading domain, establishing a power frequency phase synchronization reference and a double pilot subcarrier, controlling the electric energy meter to perform pilot loopback sampling, extracting pilot complex sampling values, calculating group time delay tail scheduling according to the pilot complex sampling values, and generating a multiplexed meter reading time slot table containing a guard interval and an uplink starting time; then, sending a downlink inquiry frame according to the scheduling sequence; freezing and sending data of the electric energy meter at a specified time; and finally, receiving, decoding and outputting a telemetry data set by the concentrator. The application can effectively avoid inter-symbol interference caused by group time delay tailing, and improve the meter reading success rate.

Description

Technical Field

[0001] This invention relates to the field of multi-channel data transmission technology, and more specifically, to an electricity meter reading system and method based on the Internet of Things. Background Technology

[0002] In power metering telemetry services for low-voltage distribution areas, multiple energy meters typically share the same low-voltage power line carrier path to transmit data to the data concentrator. Due to the complex environment of the power line medium, the carrier communication network, during information exchange, not only carries power frequency energy but is also affected by load switching, switching noise, and impedance mismatch in branch lines. Existing multiplexed meter reading scheduling mainly relies on meter address order, fixed time slot allocation, or average link quality to allocate uplink communication windows. Under the scheduling mechanism where separation is achieved by default when adjacent windows do not overlap, group delay tails are generated when uplink signals from different energy meters are reflected through the same trunk line and different branches. When this tail exceeds the absorption boundary of the system cyclic prefix, the receiver of the data concentrator will receive residual carrier energy at the preamble, pilot, or first valid symbol of adjacent energy meters. This cross-symbol signal propagation leads to meter reading frame misalignment and increased retransmission frequency, affecting the consistency of data collection time in the field and reducing the overall success rate and synchronization of metering data acquisition in the distribution area. Summary of the Invention

[0003] Firstly, an Internet of Things-based electricity meter reading system and method solves the technical problems mentioned in the background section.

[0004] This invention provides an Internet of Things (IoT)-based method for electricity meter reading, applied to common path multiplexing meter reading operations including a data concentrator, multiple target electricity meters, a common low-voltage power line path, and a master station. The data concentrator is connected to each of the target electricity meters via the common low-voltage power line path and to the master station via an IoT digital link. The method includes:

[0005] Each of the target energy meters is assigned to a multiplexed meter reading domain, and a power frequency phase synchronization reference is established based on the zero-crossing time of the power frequency on the power supply side of the data concentrator. A first pilot subcarrier and a second pilot subcarrier are allocated in the carrier communication frequency band. The target energy meters are controlled to transmit the received pilot signals back as is, so as to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier; Based on the first loopback pilot complex sampling value and the second loopback pilot complex sampling value of each target energy meter, the group delay tail is deduced, and a multiplexed meter reading time slot table including the scheduling order of each target energy meter and the final uplink start time is calculated accordingly. Send downlink meter reading query frames according to the scheduling sequence in the multiplexed meter reading time slot table; Each of the target energy meters is controlled to acquire energy metering frozen data at the corresponding final uplink start time, which is then encoded as meter reading payload and transmitted via uplink carrier. The meter reading payload is decoded and verified by centralized reception and aggregation, and a data set of electricity meter telemetry data is generated and output to the main station.

[0006] Secondly, an Internet of Things (IoT)-based electricity meter reading system is applied to a common path multiplexing meter reading operation, comprising a data concentrator, multiple target electricity meters, a common low-voltage power line path, and a master station. The data concentrator is connected to each of the target electricity meters via the common low-voltage power line path and to the master station via an IoT digital link. The system executes an IoT-based electricity meter reading method as described above. The system includes: The reference synchronization and allocation module is used to classify each of the target energy meters into the multiplexed meter reading domain, establish a power frequency phase synchronization reference based on the power frequency zero crossing time of the power supply side of the data concentrator, and allocate the first pilot subcarrier and the second pilot subcarrier in the carrier communication frequency band. The loopback sampling extraction module is used to control each of the target energy meters to transmit the received pilot signal back as is, so as to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier; The time slot scheduling deduction module is used to deduce the group delay tail based on the first loop back pilot complex sampling value and the second loop back pilot complex sampling value of each target energy meter, and calculate the multiplexed meter reading time slot table including the scheduling order of each target energy meter and the final uplink start time. The query frame sending module is used to send downlink meter reading query frames according to the scheduling sequence in the multiplexed meter reading time slot table; The uplink carrier control module is used to control each of the target energy meters to acquire energy metering frozen data at the corresponding final uplink start time, encode it as meter reading payload and transmit it via uplink carrier; The decoding and aggregation output module is used to decode and verify the meter reading payload through centralized reception and aggregation, and generate and output the electricity meter telemetry dataset to the master station.

[0007] Beneficial effects include: Based on group delay tail scheduling, this invention directly binds time slot allocation to the signal propagation delay of the communication path in the same low-voltage power line multiplexing transmission scenario, and controls the start time of each uplink in conjunction with the power frequency zero crossing time; without uniformly adding excessively large protection intervals, this invention avoids the signal aliasing of adjacent time slots caused by communication delay exceeding the cyclic prefix, reduces the probability of retransmission, improves the consistency of data collection time and the concurrent transmission efficiency of meter reading rounds. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating the principle of common low-voltage power line multiplexing topology and group delay tail generation in this invention. Figure 2 This is the timing interaction diagram of dual-pilot loopback sampling and power frequency phase synchronization of the present invention; Figure 3 This invention relates to a symbol-level tolerance protection and power frequency peak avoidance scheduling time slot diagram based on group delay. Detailed Implementation

[0009] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0010] Example 1: An IoT-based electricity meter reading method, applied to a common path multiplexing meter reading operation including a data concentrator, multiple target electricity meters, a common low-voltage power line path, and a master station. The data concentrator is connected to each of the target electricity meters via the common low-voltage power line path and to the master station via an IoT digital link. The method includes: Each of the target energy meters is assigned to a multiplexed meter reading domain, and a power frequency phase synchronization reference is established based on the zero-crossing time of the power frequency on the power supply side of the data concentrator. A first pilot subcarrier and a second pilot subcarrier are allocated in the carrier communication frequency band. The target energy meters are controlled to transmit the received pilot signals back as is, so as to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier; Based on the first loopback pilot complex sampling value and the second loopback pilot complex sampling value of each target energy meter, the group delay tail is deduced, and a multiplexed meter reading time slot table including the scheduling order of each target energy meter and the final uplink start time is calculated accordingly. Send downlink meter reading query frames according to the scheduling sequence in the multiplexed meter reading time slot table; Each of the target energy meters is controlled to acquire energy metering frozen data at the corresponding final uplink start time, which is then encoded as meter reading payload and transmitted via uplink carrier. The meter reading payload is decoded and verified by centralized reception and aggregation, and a data set of electricity meter telemetry data is generated and output to the main station.

[0011] S201, Read the list of meter addresses of each of the target energy meters, bind the meter addresses with the preset meter reading message format, and define the number of symbols required to send the meter reading payload.

[0012] Specifically, before initiating the common path multiplexing meter reading operation, the data concentrator reads the list of target energy meters in its local storage configuration unit via its internal bus interface. In some optional implementations, the total number of target energy meters is extracted, limiting this number to between 10 and 500, and a 6-byte hexadecimal hardware code is extracted for each target energy meter in the address list as the corresponding table address. Further, a preset meter reading message format is extracted in the data concentrator's communication parsing module. This preset meter reading message format includes a table address field, an energy meter reading field, a data acquisition timestamp field, and a cyclic redundancy check (CRC) field located in fixed positions; the total byte length after superimposing all the above fields is calculated and set to 32 bytes. Finally, the orthogonal frequency division multiplexing modulation and demodulation parameter configuration table used in the current low-voltage power line carrier communication network is obtained, and the payload byte capacity that each valid communication symbol can carry is extracted. The total byte length is divided by the payload byte capacity that each valid communication symbol can carry. If there is a decimal in the division result, an up-rounding operation is performed to obtain a positive integer result. The positive integer result obtained by the up-rounding operation is used as the unit of measurement for the time span required to send one frame of power data. It is directly extracted and assigned to be fixed as the number of symbols required to send the meter reading payload. Through this operation, the data concentrator establishes a mapping and binding relationship in the local memory dictionary from the table address key value to the fixed number of symbols.

[0013] S202, in the first carrier frame preamble after the zero-crossing moment of the power supply frequency on the power supply side, a first known complex pilot signal is emitted through the first pilot subcarrier, and a second known complex pilot signal is emitted through the second pilot subcarrier.

[0014] Specifically, the AC voltage waveform sampling data array of the power supply port of the data concentrator is extracted. The zero-crossing detection logic comparison operator is invoked to capture the transient real number of the voltage waveform amplitude where the polarity reverses from a negative real number to a positive real number across an absolute value of 0. This real number of the time scale is extracted and locked as the zero-crossing moment of the power supply side. In some optional embodiments, after identifying the zero-crossing moment of the power supply side, the data concentrator defines a transmission window within the communication frequency band, which is limited to a frequency range of 2 MHz to 12 MHz. Within this communication frequency band, two independent subcarrier frequency points that do not carry any actual meter reading data bits are selected and allocated. The low-frequency endpoint of these two frequency points is extracted as the first pilot subcarrier, and the high-frequency endpoint is extracted as the second pilot subcarrier. Further, the frequency spacing between the first pilot subcarrier and the second pilot subcarrier is set and constrained to be greater than or equal to two standard orthogonal frequency division multiplexing (OFDM) subcarrier frequency spacings to prevent frequency band interference. Finally, within the preamble structure of the first carrier frame to be transmitted, the data concentrator modulates and generates a combination of sinusoidal waveforms containing both specific real amplitudes and specific real phase angles using the first pilot subcarrier as a first known complex pilot signal; simultaneously, it modulates and generates another waveform sequence with a combination of specific real amplitudes and specific real phase angles using the second pilot subcarrier as a second known complex pilot signal; subsequently, the combined electromagnetic wave group containing dual-band complex pilot information is injected and diffused into the common path of the common low-voltage power line through the power line carrier analog front-end transmission radio frequency amplification circuit.

[0015] S203, control each of the target energy meters to synchronously capture the first known complex pilot signal and the second known complex pilot signal.

[0016] Specifically, each of the target energy meters located at the end of each branch of the public low-voltage power line path continuously performs real-time analog-to-digital conversion discrete sampling of the low-voltage power line channel through its built-in carrier signal coupling receiving circuit. In some optional embodiments, after the data concentrator sends the above signal, the baseband digital signal processor inside each of the target energy meters performs envelope energy detection and autocorrelation feature matching operations on the extracted discrete voltage digital quantity array; when the calculated absolute value of the envelope energy exceeds a preset 10 mV background noise threshold, and the autocorrelation peak matching is determined to be true, the reception of the first carrier frame preamble is confirmed. Further, at this time, each of the target energy meters activates the fast Fourier transform demodulation engine, using the intercepted preamble time boundary to align the time origin of its own received clock to the absolute time reference point issued by the data concentrator, thereby achieving convergence and alignment of the station area clock frequency offset. Finally, within the same time slot acquisition window, each target energy meter is specifically addressed and located in the frequency domain analysis result matrix to the frequency horizontal coordinate index position of the first pilot subcarrier and the frequency horizontal coordinate index position of the second pilot subcarrier. At the corresponding two frequency domain index addresses, the real part floating-point array and the imaginary part floating-point array containing attenuation and phase shift distortion carried in the received signal are extracted. The discrete complex matrix extracted from these two parts is locked and stored in the local buffer register as the observation sample of the receiving end. This action completes the receiving process of controlling each target energy meter to synchronously acquire the first known complex pilot signal and the second known complex pilot signal.

[0017] S301, short-time loopback trigger commands are sent sequentially to each of the target energy meters according to the ascending order of the table addresses.

[0018] Specifically, the table addresses of all target energy meters bound and mapped in the local memory dictionary of the data concentrator are extracted. In some optional implementations, these table addresses representing hexadecimal hardware devices are read and converted into unsigned long integers. Within the central processing unit, a comparison and sorting module is invoked to perform a repositioning and rearrangement operation on all table addresses according to an ascending numerical order, generating a device polling queue array with a uniquely determined sequential addressing order. This array serves as the ascending order rule for the table addresses. Further, the corresponding table addresses are extracted sequentially from the head to the tail of the device polling queue array. For each extracted table address, a Media Access Control (MAC) layer control message specifically for waking up the measurement echo probe function is assembled in the communication protocol encapsulation module of the data concentrator. The total length of this MAC layer control message is set to 16 bytes, which includes a trigger-specific command identification opcode and the table address of the addressed energy meter as the destination address. Finally, the assembled Media Access Control layer control message with the added Cyclic Redundancy Check field is extracted and defined as the short-time loopback trigger instruction. The data concentrator's underlying transmission bus waits for a fixed time interval of 10 milliseconds, and then sends the instruction sequence to each of the target energy meters in the device polling queue array via the common low-voltage power line trunk line. This fixed time interval wait period avoids overlapping congestion of the common path channel, thereby executing and completing the operation of sending the short-time loopback trigger instruction to each of the target energy meters in sequence.

[0019] S302, control each of the target energy meters to transmit the pilot symbols corresponding to the first known complex pilot signal and the second known complex pilot signal in the same way during two consecutive orthogonal frequency division multiplexing symbols in response to the short-time loopback trigger command.

[0020] Specifically, each of the target energy meters mounted on a remote branch of a public low-voltage power line continuously monitors the downlink channel medium using its internal receiving coupling front end. When a data frame is received, the destination address field information within the data frame is extracted and compared with the table address stored in its non-volatile memory using a byte-by-byte comparison. In some optional implementations, when the comparison result is a perfect match, the corresponding addressed target energy meter generates an internal hardware interrupt, temporarily suspending its regular energy metering data reading and reporting queue, causing the communication state machine to switch to a short-time loopback response working state. The system retrieves the parameter table of the current network configuration and sets the transmission time span of a single carrier communication symbol to 1 millisecond. Further, immediately after entering the short-time loopback response working state, within the allocated uplink transmission time slot, the addressed target energy meter controls the underlying timer to open a transmission time window with a length of 2 milliseconds. This time window, when joined end to end, exactly covers the time span of transmitting two complete communication symbols, and this span is defined as the two consecutive orthogonal frequency division multiplexing symbols. Finally, within the transmission time window, the target energy meter directly addresses and retrieves the frequency domain complex array data points of the first known complex pilot signal and the second known complex pilot signal, which were intercepted and latched near the zero-crossing moment in the early stage in its local baseband processing buffer register. Without any re-encryption or interleaving operation to change the amplitude and phase parameters, these complex array data points are directly used as the input frequency mapping values ​​of the inverse transformation module to modulate and generate a time-domain analog radio frequency electromagnetic band containing echo detection energy. The target energy meter uses its internal power amplifier circuit to drive the execution unit to directly couple and output the time-domain analog radio frequency electromagnetic band outward and diffuse it into the low-voltage power line branch path, and perform the original feedback operation. The time-domain analog radio frequency electromagnetic band containing dual pilot characteristics generated outward is defined as the pilot symbol corresponding to the first known complex pilot signal and the second known complex pilot signal.

[0021] S303, perform Fast Fourier Transform demodulation on the pilot symbols, and extract the first loopback pilot complex sample value and the second loopback pilot complex sample value at the first pilot subcarrier and the second pilot subcarrier, respectively.

[0022] Specifically, within the uplink receiving window of the corresponding target position, the data concentrator intercepts the discrete-time series data stream of the pilot symbols that has returned after multiple impedance reflections and amplitude attenuation through the common power line trunk and branch media via its carrier signal sensing receiving circuit. In some optional embodiments, for the intercepted discrete-time series data stream, the baseband processing core of the data concentrator first performs a cyclic prefix stripping operation, truncating the front-end guard interval data matrix with a length of 0.2 milliseconds to eliminate the overlapping effect of preceding and following symbols caused by multipath delay. Furthermore, the remaining pure symbol data sequence is then fed into the discrete integral operation kernel to perform a spatial frequency domain mapping transformation. Using an exponential conversion factor with natural numbers as the base and the product of the imaginary unit, 2, pi, the frequency horizontal axis step parameter, and the time horizontal axis step parameter as the exponent, the pure symbol data sequence is subjected to positional cross multiplication and continuous definite integral summation algebraic calculation. This completes the transformation operation from a one-dimensional time horizontal axis variable to a multi-dimensional complex spatial spectrum of frequency nodes. This overall operation process is defined as fast Fourier transform demodulation of the pilot symbols. Finally, in the frequency domain analytical result floating-point matrix with multi-frequency discrete distribution characteristics generated by demodulation output, based on the absolute frequency point coordinate mapping relationship fixed in the initialization parameter allocation stage, the address pointer jump is directly executed to accurately address and locate the specific frequency horizontal coordinate index position representing the first pilot subcarrier, and another specific frequency horizontal coordinate index position representing the second pilot subcarrier; at the first pilot subcarrier position where the addressing is hit, the composite complex number containing the real number of the actual physical channel fading amplitude change and the real number of the channel group delay phase shift deviation is independently read and extracted. The complex parameter entity combination is directly assigned and defined as the first loopback pilot complex sample value. Using completely isomorphic operation logic, at the address-hit second pilot subcarrier position, the corresponding complex parameter entity combination with the frequency response fading distortion characteristics at that specific frequency point is read and extracted, and directly assigned and defined as the second loopback pilot complex sample value. The two sets of loopback pilot complex sample values ​​that represent the objective round-trip propagation physical loss are written into the system's underlying state table as the reference parameter source for subsequent channel frequency response analysis and complex phase difference dewinding deduction.

[0023] S401, perform channel estimation based on the first loopback pilot complex sample value and the first known complex pilot signal to determine the first equivalent channel response, and perform channel estimation based on the second loopback pilot complex sample value and the second known complex pilot signal to determine the second equivalent channel response.

[0024] Specifically, the data concentrator retrieves the first loopback pilot complex sample value specific to each of the target energy meters acquired within the receiving time slot. This sample value is represented as a composite parameter array containing both real and imaginary floating-point numbers. In some optional embodiments, the first known complex pilot signal, which is pre-deployed locally, is synchronously extracted; it is also represented as a complex number containing both real and imaginary parts. Further, in the complex number operation core of the system baseband processor, the first loopback pilot complex sample value is used as the dividend entity, and the first known complex pilot signal is used as the divisor entity to perform a complex division arithmetic operation. This complex division arithmetic operation eliminates the initial amplitude and initial phase offset of the original transmitted signal, directly outputting a complex result parameter that independently characterizes the power line medium transmission attenuation and phase shift characteristics at a specific frequency point. This complex result parameter is extracted and assigned a value to define the first equivalent channel response. Finally, using a fully parallel arithmetic logic channel, the corresponding second loopback pilot complex sample value and the second known complex pilot signal are retrieved; the second loopback pilot complex sample value is used as the dividend entity, and the second known complex pilot signal is used as the divisor entity, and the same complex division arithmetic calculation operation is performed; the complex result parameter reflecting the channel attenuation and phase shift characteristics at another specific frequency point is extracted from the calculation output and assigned to form the second equivalent channel response.

[0025] S402, extract the complex phase difference between the second equivalent channel response and the first equivalent channel response to obtain the phase frequency response characteristics of the common low-voltage power line path.

[0026] Specifically, after obtaining the equivalent channel responses at the two independent frequency points, the complex polar coordinate transformation operator component of the digital signal processor is invoked. In some optional implementations, for the first equivalent channel response, its independent imaginary real value is extracted as the dividend, and its independent real value is extracted as the divisor. Division is performed to obtain a first tangent ratio real number. This first tangent ratio real number is substituted into the arctangent trigonometric function calculation module to obtain a first phase angle real number limited to a closed interval between negative and positive pi values. Similarly, for the second equivalent channel response, its independent imaginary real value is extracted and divided by its real real value to obtain a second tangent ratio real number. This second tangent ratio real number is substituted into the arctangent trigonometric function calculation module to obtain a second phase angle real number also limited to this closed interval. Finally, the obtained real number of the second phase angle is used as the minuend, and the real number of the first phase angle is used as the subtrahend. The two are fed into the subtractor to perform a subtraction arithmetic operation. The one-dimensional floating-point real number deviation value obtained from the subtraction arithmetic operation is extracted. This floating-point real number deviation value objectively reflects the phase rotation asynchrony difference between two specific pilot frequency points when crossing the same low-voltage carrier network. It is directly assigned and extracted as the phase frequency response characteristic of the common low-voltage power line path. The above steps complete the operation of extracting the complex phase difference between the second equivalent channel response and the first equivalent channel response.

[0027] S403, perform phase dewinding processing on the complex phase difference to eliminate the influence of the phase return boundary, and extract the group delay tail of each of the target energy meters based on the phase difference after dewinding and the frequency interval relationship between the first pilot subcarrier and the second pilot subcarrier.

[0028] Specifically, the floating-point real-valued deviation of the complex phase difference output from the preceding calculation is extracted. Given that the calculated range of the arctangent trigonometric function is periodically folded and truncated within the range of negative to positive pi, it is prone to phase jumps due to multipath delays during long-distance transmission, thus losing the true linear phase slope. In some optional implementations, a threshold for determining a phase jump is set internally within the system, specifically assigned the value of pi. When the absolute value of the floating-point real-valued deviation is detected to be greater than pi, a compensation logic operator is invoked to introduce an integer multiple correction factor. By increasing or decreasing the period of integer multiples of pi, the phase difference value of the jump is smoothly aligned to a state where the slope of the adjacent frequency point maintains a linear and monotonically extending extension. Furthermore, through this continuous compensation calculation across the periodic boundary, the phase dewinding process of the complex phase difference is completed to eliminate the influence of the phase foldback boundary, and the compensated and restored dewinding phase difference value is output outward. Specific frequency point values ​​of the first and second pilot subcarriers set in the previous step are extracted, the absolute value of the frequency difference between the two frequency points is calculated, and the frequency interval parameter between them is obtained. This frequency interval parameter is then constrained within a fixed bandwidth range of 10000 Hz to 50000 Hz. Finally, based on the corresponding conversion relationship between the dewinding phase difference and the angular frequency span, the frequency domain phase change characteristics are converted into time domain propagation duration values ​​to obtain the round-trip group delay of the corresponding power line path. Combining the low-voltage power line branch reflection characteristics with the preset mapping rule of the round-trip group delay, the group delay tail of each of the target energy meters is deduced.

[0029] S501, the tail overflow time is defined based on the portion of the group delay tail that exceeds the preset safe cycle prefix duration.

[0030] Specifically, the floating-point real-time value of the group delay tail of each of the target energy meters currently undergoing time slot scheduling is retrieved from the calculations obtained in the previous deduction steps. In some optional implementations, the cyclic prefix duration specified under the Orthogonal Frequency Division Multiplexing (OFDM) modulation and demodulation technology standard is extracted from the system's underlying communication protocol parameter configuration library, and this cyclic prefix duration is specifically assigned a value of 0.0002 seconds; a safety margin ratio for absorbing multipath reflection delay energy is set and assigned a value of 0.8. Further, the cyclic prefix duration is multiplied by the safety margin ratio to calculate an absolute value of a safe time boundary that is free from interference from residual energy of adjacent carriers, and this absolute value of the safe time boundary is extracted and defined as the preset safe cyclic prefix duration. Finally, in the comparison and calculation module of the central control processor, the floating-point real time value of the group delay tail is used as the minuend, and the preset safe cycle prefix duration is used as the subtrahend. A subtraction operation is performed to obtain a real time difference value. The real time difference value is compared with 0. When the real time difference value is greater than 0, it indicates that the residual carrier energy generated by the physical link has exceeded the system's default safe absorption interval boundary in terms of time span. The real time difference value is directly extracted and assigned as the tail overflow time. When the real time difference value is less than or equal to 0, it indicates that the carrier reflection energy has attenuated to the background noise level within the safe prefix interval. At this time, 0 is directly assigned as the tail overflow time. Through this bottom-line comparison interception and subtraction calculation mechanism with 0 as the lower bound, the actual propagation time exceeding the absorption tolerance is accurately extracted. Thus, the tail overflow time is defined based on the portion of the group delay tail that exceeds the preset safe cycle prefix duration.

[0031] S502, combined with the preset symbol stability margin, performs time-domain tolerance compensation on the tail overflow time, and maps the compensated tail overflow time to an integer multiple span of the duration of a single orthogonal frequency division multiplexing symbol, generating a symbol-level protection interval for isolating inter-symbol interference.

[0032] Specifically, the duration of a single orthogonal frequency division multiplexing symbol configured in the current network communication specification is extracted and fixed to 0.001 seconds. In some optional implementations, an additional safety time parameter is set specifically to prevent transient changes in the low-voltage power grid, slight jitter in the sampling clock, and superposition of receiver filter response delays. This parameter is set to 0.00025 seconds and established as a preset symbol stability margin. Further, the floating-point time level corresponding to the tail overflow time output by the pre-processor logic is retrieved; the tail overflow time and the preset symbol stability margin are fed into an adder for summation arithmetic operation, and a time-wide capacity real number covering the objective fluctuation fault tolerance and redundancy characteristics of the system is calculated and output. The real number output by the summation arithmetic operation is directly extracted and defined as the compensated tail overflow time. This action completes the time-domain tolerance compensation of the tail overflow time in combination with the preset symbol stability margin. Finally, the compensated tail overflow time is used as the dividend entity, and the duration of a single orthogonal frequency division multiplexing symbol is used as the divisor entity. A division calculation is performed to obtain a floating-point ratio result that reflects the proportion of the current tail overflow amount to the symbol period of the communication system. The floor function is called on this floating-point ratio result. The specific execution logic is to determine whether the floating-point ratio result has a fractional part greater than 0. If it does, all fractional data is discarded directly, and a carry-in operation of adding 1 is performed on its integer part to obtain a minimum positive integer scalar that is definitely greater than or equal to the original floating-point ratio result. This minimum positive integer scalar is extracted and defined as the integer multiple span after the mapping transformation. The minimum positive integer of the obtained integer multiple span is multiplied by the duration of the single orthogonal frequency division multiplexing symbol. This multiplication calculation forces the originally continuously distributed time overflow attenuation tail amount to be discretely aligned and extended to the discrete symbol boundary of the communication system. The final floating-point time length constant entity generated by the output is assigned to generate a symbol-level protection interval for isolating inter-symbol interference.

[0033] S503, the scheduling order of each target energy meter is determined according to the ascending order of the group delay tail amount of each target energy meter, and the ascending order of the table address is used as an arbitration mechanism under the condition of equality.

[0034] Specifically, the floating-point real values ​​of the group delay tail of each of the target energy meters within the same multiplexed meter reading domain are extracted, along with the integer identifier real values ​​of the table addresses of each of the target energy meters after conversion. In some optional implementations, in the array sorting deduction module of the system's central processing unit, any specific target energy meter to be scheduled and evaluated is selected; an initial accumulator register is created specifically for calculating the final sorting position offset of that specific target energy meter, and its initial value is fixed at 1. Furthermore, a global loop traversal mechanism is initiated to scan and retrieve all target energy meters within the multiplexed meter reading domain, excluding the specific target energy meter. During each loop traversal comparison, the group delay tail of the comparison object and the group delay tail of the specific target energy meter are compared and their magnitudes are determined. When the group delay tail of the comparison object is less than the group delay tail of the specific target energy meter in absolute value, the counting condition of the ascending order rule is triggered, instructing the current value inside the initial accumulator register to be incremented by 1. When a comparison object is found... When the group delay tail is exactly equal to the group delay tail of the specific target energy meter, a conflict of equal group delay tail occurs. At this time, an arbitration mechanism based on the ascending order of the table address is activated as an equal condition. Under this decision logic branch, the table address values ​​of the two are further compared. If the integer identifier of the table address of the comparison object is less than the integer identifier of the table address of the specific target energy meter, it is determined that the comparison object should be placed at the beginning of the time slot sequence, and the current value inside the initial accumulator register is also incremented by 1. Finally, after completing the full traversal comparison and register condition summation of all other energy meters in the same domain, the final frozen positive integer value in the initial accumulator register precisely represents the exact transmission timing scheduling order of the specific target energy meter under the principle of avoiding low-voltage public line channel trailing interference. The final output positive integer value is extracted and directly assigned as the scheduling order of each target energy meter. Through this permutation system calculation unit, which does not rely on any abstract model and contains a logic to break the tie arbitration, the unique time slot sequence set of all scheduled target devices is calculated and established, providing precise discrete order parameters for preventing signal aliasing and calculating future communication time anchors.

[0035] S601 determines the power frequency half-cycle duration based on the power frequency parameters of the power supply network.

[0036] Specifically, the operating cycle reference parameter of the current low-voltage distribution area AC line is extracted, namely the power frequency parameter of the power supply network. In some optional embodiments, the specific value of the power frequency parameter of the power supply network is assigned to 50 Hz. Further, in the arithmetic operation unit, 1 is used as the dividend entity, and the product of 2 and 50 Hz, 100, is used as the divisor entity. Finally, a division operation is performed on the dividend entity and the divisor entity to obtain a floating-point time scalar representing half a sinusoidal AC oscillation cycle; the 0.01 seconds calculated from this floating-point time scalar is extracted and directly assigned as the power frequency half-cycle duration, which serves as the basic time measurement operator for subsequent avoidance of periodic interference noise.

[0037] S602, based on the final uplink start time of the target energy meter in the prior scheduling sequence, the number of symbols required to send the meter reading payload, and the time-domain sequence of the symbol-level protection interval, the earliest allowed communication start time of the target energy meter in the current scheduling sequence is deduced.

[0038] Specifically, in the global loop of the time-slot scheduling derivation, the sequence number of the target energy meter in the scheduling queue is determined. If the sequence number is 1, the absolute value of the global start reference time for this meter reading round preset by the system is directly assigned to the energy meter. In some optional implementations, if the sequence number is greater than 1, the exclusive scheduling parameter set of the adjacent sequence node directly in front of it, i.e., the target energy meter in the earlier scheduling sequence, is extracted. From this parameter set, the pre-arranged absolute trigger clock scale, i.e., the final uplink start time, the number of symbols required to send the meter reading payload by occupying the communication channel, and the symbol-level protection interval specifically used to isolate physical tail energy are extracted. Further, the duration of a single orthogonal frequency division multiplexing symbol configured at the network bottom layer is retrieved and assigned a value of 0.001 seconds. The number of symbols required to send the meter reading payload is multiplied by the 0.001 seconds to calculate the real number of the payload transmission duration. Finally, the three real scalars—the payload transmission duration, the symbol-level protection interval, and the final uplink start time—are fed into an adder for arithmetic summation. The output of this summation includes an absolute time scale encompassing the span of all preceding actual communication time slots and the channel silent waiting overhead, which constitutes the safe avoidance connection boundary point of the time-domain sequence. This absolute time scale is extracted and defined as the earliest allowed communication start time of the target energy meter in the current scheduling sequence.

[0039] S603, using the zero-crossing moment of the power supply side as the time reference anchor point, align the earliest allowed communication start time in the positive direction of the time axis to the midpoint of the first half-cycle of the power frequency, and set it as the final uplink start time of the target energy meter of the current scheduling sequence to avoid power frequency transient noise.

[0040] Specifically, the system retrieves the absolute time marker, which is captured, locked, and retained at the zero-crossing point of the AC voltage waveform polarity reversal, i.e., the zero-crossing moment of the power supply frequency, and anchors it on the overall one-dimensional time elapsed axis as the time reference anchor point. In some optional embodiments, the floating-point real number of the earliest allowed communication start time is extracted, and the floating-point real number of the zero-crossing moment of the power supply frequency is subtracted from it to obtain a time difference parameter; the time difference parameter is divided by 0.01 seconds corresponding to the power frequency half-cycle duration to obtain the relative half-cycle span real number ratio. Further, 0.5 is subtracted from the relative half-cycle span real number ratio, and the round-up arithmetic operator is called on the result of the subtraction to discard all decimal places and carry up to obtain an integer half-cycle index offset reflecting the offset step of the whole cycle; 0.5 is added to the integer half-cycle index offset, and then multiplied by the 0.01 seconds to obtain the alignment offset. Finally, the alignment offset is added to the zero-crossing time of the power supply frequency on the power supply side. This arithmetic translation mechanism accurately aligns the earliest allowed communication start time to the midpoint of the first power frequency half-cycle in the positive direction of the time axis. Since the midpoint of the power frequency half-cycle of the AC power grid is naturally in the absolutely stable region of the voltage waveform peak or valley, this translation alignment operation completely avoids the high-frequency glitches caused by the frequent switching in and out of inductive or capacitive loads on the user side near the zero-crossing point, thus perfectly achieving the goal of avoiding power frequency transient noise. The time coordinate scalar with high anti-interference safety characteristics generated after the right-shift alignment is formally established and assigned the value as the final uplink start time of the target energy meter in the current scheduling sequence.

[0041] S604, the table address, the final uplink start time, the number of symbols required to send the meter reading payload, and the symbol-level protection interval are fixedly written into the multiplexed meter reading time slot table.

[0042] Specifically, a two-dimensional relational database array structure space is allocated in the communication controller memory management unit of the data concentrator. In some optional implementations, the hardware identification hexadecimal code of the target energy meter that has completed all peak-shaving delay calculations, i.e., the table address, is extracted and written into the structure space as the primary key of the row record. Further, in the continuous memory field column bound in parallel with the primary key, the high anti-interference absolute trigger clock scale obtained above, i.e., the final uplink start time, is filled in sequentially; then, the number of symbols required to send the meter reading payload, generated according to the target message communication protocol length matching mapping, is extracted and filled in; finally, the symbol-level protection interval, specifically used to maintain channel silent waiting, is filled in according to the delay overflow compensation calculated in the early stage based on the specific branch line group. Finally, the discrete parameters of these four specific dimensions are packaged into a complete single-device time slot scheduling instruction record; according to the absolute order of increasing scheduling sequence from smallest to largest, the same parameter aggregation and data injection operations are performed on all target energy meters under the jurisdiction of the transformer area; through the read-only anti-tampering state lock instruction, the solidification writing action is performed to generate a global communication control status form in the system memory containing the absolute timing rules of multi-device concurrent avoidance and collaborative silence, and the form is defined as a whole and output as the multiplexed meter reading time slot table, which is used to directly guide the underlying carrier modem to issue targeted independent wake-up and data extraction query listening sequences.

[0043] S701, according to the scheduling order in the multiplexed meter reading time slot table, the downlink meter reading query frame is sent sequentially before the corresponding final uplink start time arrives.

[0044] Specifically, the processing core of the data concentrator reads the multiplexed meter reading time slot table that has been generated and stored in the underlying running memory. In some optional implementations, the scheduling sequence number, starting from 1 and increasing unidirectionally, is extracted from the table; based on the order of the scheduling sequence number, the absolute timestamp of the final uplink start time specifically allocated to the target energy meter in the current job sequence is located and extracted one by one. Further, a transmission advance time is set in the system control flow to ensure the preparation time for the underlying hardware of the energy meter to receive, decode, and identify instructions, and this transmission advance time is specifically assigned a value of 0.05 seconds; the absolute timestamp of the final uplink start time is subtracted from the transmission advance time to obtain a transmission action instruction time with advance trigger indication characteristics. Finally, at the time elapsed corresponding to the actual time of the sent action command, the data concentrator assembles and generates a command byte stream at the medium access control layer, which includes the target energy meter hardware addressing code, the meter reading function identification operation code, and the error correction check code. The overall size of the command byte stream is set to 16 bytes. The command byte stream is mapped and encapsulated by the carrier modulator to form the downlink meter reading query frame. Then, the carrier analog transmission front-end amplifier circuit of the concentrator port is activated, and the frame signal is directionally emitted outward through the common low-voltage power line trunk medium. In this way, the downlink meter reading query frame is sent in sequence according to the scheduling order in the multiplexed meter reading time slot table before the corresponding final uplink start time arrives.

[0045] S702, when the final uplink start time arrives, open the receive time slot window, and after the receive time slot window ends, maintain carrier communication silence for the duration of the symbol-level guard interval.

[0046] Specifically, the underlying communication controller of the data concentrator continuously reads the real number of the local real-time shifted reference clock. In some optional implementations, when the real number of the reference clock advances and reaches a value that is completely equal to the real number of the absolute timestamp of the final uplink start time issued for the current specific target energy meter, the data concentrator determines that the uplink transmission action of the target energy meter has been triggered on time, and then activates its internal carrier signal induction receiving coupling circuit and analog-to-digital conversion array channel to start the sampling action of listening to and receiving the uplink carrier signal, thereby opening the receiving time slot window when the final uplink start time arrives. Furthermore, the system retrieves the positive integer parameter corresponding to the number of symbols required to transmit the meter reading payload, which is bound to the specific configuration of the target energy meter, and obtains the duration of a single orthogonal frequency division multiplexing symbol in the unified configuration of the underlying network specifications. The two are then multiplied to obtain the real number of the time span corresponding to the receiving period. The real number of the absolute timestamp of the final uplink start time is added to the real number of the time span to obtain the expected receiving cutoff time. When the real number of the local reference clock advances to the receiving cutoff time, the gating switch of the analog-to-digital conversion receiving channel is turned off, and the receiving time slot window is ended and closed. Finally, the real value of the symbol-level protection interval time length generated by the dedicated mapping of the current communication node path group delay tail amount in the early simulation and scheduling stage is retrieved in parallel. Starting from the receiving cutoff time, within a duration period that is exactly equal to the real value of the symbol-level protection interval time length, the data concentrator actively cuts off the power supply and enable of its own carrier transmission module and receiving decoding enable port, and does not actively send any interrogation or listening to carrier pulse sequences. In this state, the carrier communication remains silent for the duration of the symbol-level protection interval, leaving a blank period to wait for the residual tail energy spreading in the current branch path to decay to below the background noise level.

[0047] S703, control the corresponding target energy meter to acquire the energy metering freeze data at the first orthogonal frequency division multiplexing symbol boundary at the final uplink start time.

[0048] Specifically, after receiving and successfully parsing the downlink meter reading query frame sent by the data concentrator, the target energy meter mounted on the remote branch line extracts the expected uplink scheduling command indicated within the frame and enters a data transmission preparation countdown synchronization state. In some optional implementations, when the internal calibration clock of the target energy meter reaches the agreed final uplink start time, the microprocessor triggers the start of the uplink carrier modulation transmission interrupt response routine. Further, at the first communication time slice start boundary position before coupling the output carrier energy waveform to the common low-voltage line, i.e., at the first orthogonal frequency division multiplexing symbol boundary of the final uplink start time, the main control microprocessor of the target energy meter sends an instantaneous register latch read electrical signal command to the dedicated energy metering core chip through the internal integrated circuit interconnect bus. Finally, within a nanosecond delay period after receiving the latch read electrical signal instruction, the dedicated chip for the core of the energy metering immediately copies the snapshot of dynamically changing power consumption parameters, such as the actual values ​​of active and reactive energy readings obtained from the current internal cumulative calculation, and stores them in a dedicated independent static random access memory block. The power consumption parameter data block that reflects the transient power consumption accumulation state at the absolute trigger moment, obtained from this copy, is extracted as the energy metering frozen data.

[0049] S704, the meter identifier, meter reading and acquisition time are encoded into the meter reading payload and transmitted uplink, and the uplink carrier output is stopped after the number of symbols required to transmit the meter reading payload is completed.

[0050] Specifically, after acquiring the dataset in a statically archived state, the baseband communication processing unit of the target energy meter initiates the uplink message data bit splicing and assembly construction program; it extracts the device's unique address code, consisting of a 6-byte hexadecimal machine hardware code, which is factory-fixed in the non-volatile storage medium, and defines and maps it as the energy meter identifier. In some optional embodiments, the specific energy consumption integer value represented by 4 bytes is extracted from the aforementioned isolated energy metering frozen data, and defined and mapped as the meter reading; the local clock year, month, day, hour, minute, and second format parameters corresponding to the instant the freeze-lock action is executed are extracted and converted into a 4-byte standardized timestamp integer variable, which is defined and mapped as the acquisition time. Furthermore, the three structured independent data segments—meter identifier, meter reading, and acquisition time—obtained through extraction and aggregation are sequentially spliced ​​together. A 2-byte error detection and verification feature suffix generated using a cyclic redundancy check (CRC) algorithm is appended to the end of this spliced ​​assembly. The spliced ​​one-dimensional digital array containing the verification suffix is ​​then subjected to channel interleaving, displacement arrangement, and orthogonal phase shift keying (QPS) mapping operations. After modulation to generate a frequency domain complex discrete array, an inverse fast Fourier transform (IFFT) process is performed to generate a time domain discrete digital level sequence. This time domain discrete digital level sequence is then fed into a digital-to-analog converter and power amplifier circuit to be combined and converted into a radio frequency analog signal waveform. This entire sequence forms the meter reading payload and is transmitted uplink via a low-voltage power line communication medium. Finally, during the continuous carrier transmission process, a dedicated symbol transmission step-increment counter is configured in the underlying driver of the target energy meter. Each time the analog radio frequency band length of an orthogonal frequency division multiplexing symbol is fully transmitted and coupled outwards, the internal storage value of this symbol transmission step-increment counter is incremented by 1. Within each transmission cycle, the internal storage value is continuously compared to a specific positive integer constant corresponding to the pre-allocated and determined number of symbols required to transmit the meter reading payload. When the comparison condition is met, the counter immediately triggers a hardware-level drive cutoff blocking signal. This drive cutoff blocking signal cuts off the baseband waveform input stream to the carrier analog transmission radio frequency front-end, enabling the external transmission channel to quickly present a high-impedance anti-interference reception blocking mode. Through the above comparison and interception actions, the uplink carrier output stops after the number of symbols required to transmit the meter reading payload is completed, actively clearing the channel occupancy status to allow the next scheduled meter position in the same area to transmit data back without obstruction.

[0051] S801, within the receiving time slot window corresponding to the final uplink start time, extract the received carrier signal.

[0052] Specifically, the underlying timer module of the data concentrator continuously reads the locally synchronized absolute clock floating-point real number. In some optional implementations, when the absolute clock floating-point real number evolves and reaches the numerical node of the final uplink start time pre-assigned to the current specific target energy meter in the multiplexed meter reading time slot table, the data concentrator determines that the uplink transmission action of the target energy meter has been triggered on time, and then activates its internal carrier receiving analog front-end amplifier circuit and analog-to-digital converter hardware array, thereby initiating a listening sampling action within the receiving time slot window corresponding to the final uplink start time. Further, the fixed discrete sampling frequency of the analog-to-digital converter hardware array is set to 4 MHz; within the continuous time span of the receiving time slot window, the analog-to-digital converter hardware array is controlled to continuously sense, intercept, and quantize discrete voltage amplitude real numbers from the low-voltage power line medium at the frequency of 4 MHz. Finally, the discrete voltage amplitude real numbers of electromagnetic energy fluctuations that are captured during this time period and continuously fluctuate over time are arranged and reassembled in chronological order to form a one-dimensional time-domain floating-point array sequence. This one-dimensional time-domain floating-point array sequence is extracted and output from the underlying register as a whole, and directly assigned to be the received carrier signal. It is then sent to the post-processing buffer to wait for digital demodulation.

[0053] S802, the carrier signal is sequentially subjected to fast Fourier transform, equalization, deinterleaving, channel decoding and cyclic redundancy check.

[0054] Specifically, in the baseband digital signal processor, the cyclic prefix guard interval data points used to absorb multipath delay at the front end of the carrier signal sequence are first removed. For the clean symbol data array after removing the prefix, a transformation operation factor with a natural number as the base and a composite exponent consisting of the product of the negative sign, the imaginary unit, 2, pi, the frequency horizontal axis index, and the time horizontal axis step is used to perform positional cross multiplication and definite integral summation arithmetic operations on the clean symbol data array and the transformation operation factor. This completes the mapping transformation from a one-dimensional time domain amplitude sequence to a multi-dimensional frequency domain complex discrete array, i.e., the fast Fourier transform is completed. In some optional implementations, the equivalent channel response complex estimate corresponding to the communication path of the electricity meter is obtained from the previous deduction based on the short-time loopback pilot detection. The measured complex values ​​of each subcarrier in the frequency domain complex discrete array obtained by the fast Fourier transform are used as the dividend, and the equivalent channel response complex estimate is used as the divisor to perform complex division operation, thereby offsetting the amplitude attenuation and phase deflection distortion caused by long-distance medium transmission and completing the equalization process. Furthermore, for the discrete soft-decision log-likelihood ratio numerical sequence output after equalization, according to the matrix permutation address addressing reverse mapping rule set by the system transmitter, the originally scattered numerical values ​​are shifted back to their original writing order positions, and the concentrated bursts of continuous errors are scattered and distributed into discrete random independent error terms, thus completing the deinterleaving process. The deinterleaved sequence array is then input into the decoding operator kernel, and using the preset maximum likelihood probability convolutional grid state machine model, the globally optimal survival path trajectory with the smallest absolute value of the cumulative branch Hamming distance is explored and traced backward from back to front. Based on this, a one-dimensional digital sequence array representing the original binary bit stream is restored and output, thus completing the channel decoding. Finally, the main bit segment of the restored one-dimensional digital sequence array is extracted as the dividend polynomial entity, and the fixed generator polynomial entity preset at the bottom layer of the system communication protocol is extracted as the divisor. Algebraic division with modulus 2 is performed to calculate the remainder term. When it is determined that the obtained remainder term is equal to 0, it is confirmed that the one-dimensional digital sequence array has not undergone content bit flipping variation during channel transmission and transformation. In this way, a truth value identifier that has passed the output verification is generated, and the cyclic redundancy check is completed.

[0055] S803, the meter reading payload that has passed the cyclic redundancy check is mapped to a telemetry data record containing the electricity meter identifier, the meter reading, and the acquisition time.

[0056] Specifically, after the underlying verification processor outputs a truth value instruction status code that has passed the cyclic redundancy check, the data concentrator extracts the complete binary bit sequence segment that has passed the error detection interception stored in the current receive demodulation buffer, and establishes and retains the entire bit sequence segment as the meter reading payload. In some optional implementations, within the system memory application layer unpacking and parsing component, the meter reading payload is segmented into byte segments according to a predetermined protocol frame structure offset address dictionary; a hexadecimal machine hardware feature code of 6 consecutive bytes extending sequentially from the starting position of the first byte of the protocol payload data area is extracted as a positioning reference and directly assigned as the energy meter identifier. Furthermore, moving backward by a preset interval offset, the system continues to extract the subsequent four-byte data block array. It then uses a floating-point number conversion rule or an integer multiplication operator to convert this data into a floating-point real value representing the actual active energy consumed, and assigns this value as the meter reading. Next, it shifts backward again to extract another four-byte encoded array set, imports it into the timestamp conversion logic component, decodes it to a corresponding absolute time node scale combination containing calendar year, month, day, hour, minute, and second parameters, and assigns this value as the acquisition time. Finally, a formatted one-dimensional relational data row structure entity dictionary is established in the data encapsulation area of ​​the main control processing unit. The three independent feature parameter entities—the energy meter identifier, the meter reading, and the acquisition time—extracted sequentially are pushed into the corresponding field slots of this data row structure entity dictionary according to the header settings, and associated locking is performed. This data row structure entity, which has completed the assembly, aggregation, and reorganization of all key business fields, is directly finalized, output, and defined as a telemetry data record.

[0057] S804 After processing all the target energy meters included in the multiplexed meter reading time slot table, the summarized telemetry data is recorded and integrated into the energy meter metering telemetry dataset, and then transmitted back to the master station via the Internet of Things digital link.

[0058] Specifically, the task polling scheduling engine of the data concentrator continuously tracks the execution progress counter of the current batch of read tasks; whenever the underlying layer successfully extracts, parses, and assembles a corresponding telemetry data record, the internal real value of the execution progress counter is incremented by 1. In some optional implementations, when the comparator determines that the real value in the execution progress counter is completely equal to the total number of initial registered query tasks in the multiplexed meter reading time slot table, or when it detects that the system's local absolute clock has crossed the deadline safety interval boundary time of the last receiving time slot window in the time slot table, the system's main control logic determines that the current single-round multiplexed read operation scheduled based on the group delay avoidance mechanism has been completely terminated, thereby confirming that it has entered and is in the state stage after processing all the target energy meters included in the multiplexed meter reading time slot table. Furthermore, in this state phase, the concentrator retrieves in batches all the independently distributed telemetry data records that were dynamically generated and temporarily stored during this polling period from the local volatile buffer storage medium; all the recalled telemetry data records are uniformly loaded into a comprehensive hierarchical text storage archive containing a globally unique identification header field and an anti-tampering encrypted error detection signature tail field; the text storage archive is then spatially serialized and data packetized at the software level, and the overall output is assigned as the electricity meter telemetry dataset. Finally, the data concentrator activates the wireless cellular communication RF antenna module or fiber broadband transmission modulation module configured on its uplink communication backplane. Using the transmission control protocol and the telemetry transmission application layer communication message agreement, it establishes a long-connection external data transmission tunnel with the remote data center server. This long-connection external data transmission tunnel is set as the IoT digital link. The fully encapsulated electricity meter telemetry dataset is directly injected into the uplink transmission buffer queue of the IoT digital link as effective communication content. The underlying hardware controller modulates it into a continuous microwave RF pulse signal group or optical frequency scintillation pulse signal group and delivers it to external space or optical medium. This completes the remote collection and interactive closed-loop process of data back to the master station via the IoT digital link.

[0059] Example 2: An IoT-based electricity meter reading system is applied to a common path multiplexing meter reading operation, comprising a data concentrator, multiple target electricity meters, a common low-voltage power line path, and a master station. The data concentrator is connected to each of the target electricity meters via the common low-voltage power line path and to the master station via an IoT digital link. The system executes the aforementioned IoT-based electricity meter reading method. The system includes: The reference synchronization and allocation module is used to classify each of the target energy meters into the multiplexed meter reading domain, establish a power frequency phase synchronization reference based on the power frequency zero crossing time of the power supply side of the data concentrator, and allocate the first pilot subcarrier and the second pilot subcarrier in the carrier communication frequency band. The loopback sampling extraction module is used to control each of the target energy meters to transmit the received pilot signal back as is, so as to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier; The time slot scheduling deduction module is used to deduce the group delay tail based on the first loop back pilot complex sampling value and the second loop back pilot complex sampling value of each target energy meter, and calculate the multiplexed meter reading time slot table including the scheduling order of each target energy meter and the final uplink start time. The query frame sending module is used to send downlink meter reading query frames according to the scheduling sequence in the multiplexed meter reading time slot table; The uplink carrier control module is used to control each of the target energy meters to acquire energy metering frozen data at the corresponding final uplink start time, encode it as meter reading payload and transmit it via uplink carrier; The decoding and aggregation output module is used to decode and verify the meter reading payload through centralized reception and aggregation, and generate and output the electricity meter telemetry dataset to the master station.

[0060] like Figure 1As shown, this embodiment provides a schematic structure illustrating the principle of public low-voltage power line multiplexing topology and group delay tail generation. The main station establishes a communication connection with a data concentrator via an IoT digital link. The data concentrator is connected to the public low-voltage power line trunk, and multiple target energy meters are connected to this trunk via branch lines of varying lengths. During actual operation, the public low-voltage power line trunk simultaneously carries power frequency energy, communication carrier waves, and user-side load current. Each branch line also connects to different types of loads such as lighting, sockets, motors, water pumps, and household appliances. When the data concentrator sends downlink communication signals to each target energy meter, the communication signals propagate along the public low-voltage power line trunk and enter the corresponding branch line at each branch access point. Due to the different lengths of the branch lines and the differences in the impedance states of the user-side loads, some communication energy is reflected at the branch ends, load ends, and locations of impedance discontinuities, forming different round-trip physical propagation paths. For target energy meters with shorter branches and better impedance matching, the return attenuation is faster and the carrier tail is shorter. For target energy meters with longer branches or more significant impedance mismatch, the return propagation time is longer and the residual carrier energy lasts longer, forming a more obvious group delay tail. Therefore, although the same common low-voltage power line trunk is shared by multiple target energy meters, the different branch paths and load states of each target energy meter result in different lengths of physical tails in their uplink communication signals at the concentrator receiving side. These physical tails serve as the objective basis for subsequent differentiated time slot scheduling and protection interval settings.

[0061] like Figure 2 As shown, this embodiment provides a timing interaction process for dual-pilot loopback sampling and power frequency phase synchronization. The data concentrator uses the zero-crossing moment of the power frequency voltage waveform on the power supply side as a unified phase reference, and sends dual-pilot signals to the target energy meter at the preamble position of the first carrier frame after this zero-crossing moment. These dual-pilot signals are respectively set at two predetermined pilot subcarrier positions within the carrier communication frequency band, representing the first known complex pilot signal and the second known complex pilot signal. After receiving the carrier frame preamble, the target energy meter maintains synchronous identification of the power frequency phase reference and the carrier frame boundary. Subsequently, the data concentrator sends a short-time loopback trigger command to the target energy meter. Upon receiving the trigger command, the target energy meter enters a short-time loopback response state and transmits the received pilot content back as is within two consecutive orthogonal frequency division multiplexing symbol windows. The data concentrator receives the loopback pilot signal transmitted back by the target energy meter in the corresponding uplink receiving time slot and extracts the first loopback pilot complex sample value and the second loopback pilot complex sample value at the two pilot subcarrier positions, respectively. Through this interactive process, the data concentrator can obtain the frequency domain response information of the power line path corresponding to the target energy meter under a unified power frequency phase reference, providing basic sampling data for subsequent judgment of channel propagation delay, tailing status, and formulation of multiplexed meter reading time slots.

[0062] like Figure 3 As shown, this embodiment provides a symbol-level tolerance protection and power frequency peak avoidance scheduling time slot arrangement method based on group delay. During meter reading scheduling, the data concentrator determines whether the tail might exceed the safe cyclic prefix absorption range based on the end time of the uplink data frame of the previous scheduling sequence target energy meter and the group delay tail generated by the path corresponding to the target energy meter. After the data frame of the previous target energy meter ends, its residual carrier energy may still exist in the common low-voltage power line path. If the residual tail directly enters the uplink receiving window of the next target energy meter, it may interfere with the preamble, pilot, or valid symbols of the next frame. Therefore, a symbol-level protection interval is set after the end of the data frame of the previous target energy meter, and carrier communication is kept silent within the protection interval to wait for the residual tail to decay to a safe range. After the protection interval ends, the earliest allowed communication start time of the current scheduling sequence target energy meter is obtained, but this time is not directly used as the final uplink start time, but continues to be aligned backward along the time axis to the midpoint of the first power frequency half-cycle. Because the area near the zero-crossing of the power frequency is more susceptible to transient noise from load switching, and the midpoint of the power frequency half-cycle can serve as a relatively stable communication safety anchor point, the final uplink start time of the current target energy meter is set at this safety anchor point. At this final uplink start time, the target energy meter acquires the frozen energy metering data and begins sending uplink carrier data frames. This suppresses group delay tail interference while avoiding time windows with strong power frequency periodic noise, thus improving the reliability and synchronization of multiplexed meter reading for multiple targets.

[0063] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A method for reading electricity meters based on the Internet of Things (IoT), applied to a common path multiplexing meter reading operation including a data concentrator, multiple target electricity meters, a common low-voltage power line path, and a master station, wherein the data concentrator is connected to each of the target electricity meters via the common low-voltage power line path and to the master station via an IoT digital link, characterized in that, The method includes: Each of the target energy meters is assigned to a multiplexed meter reading domain, and a power frequency phase synchronization reference is established based on the zero-crossing time of the power frequency on the power supply side of the data concentrator. A first pilot subcarrier and a second pilot subcarrier are allocated in the carrier communication frequency band. The target energy meters are controlled to transmit the received pilot signals back as is, so as to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier; Based on the first loopback pilot complex sampling value and the second loopback pilot complex sampling value of each target energy meter, the group delay tail is deduced, and a multiplexed meter reading time slot table including the scheduling order of each target energy meter and the final uplink start time is calculated accordingly. Send downlink meter reading query frames according to the scheduling sequence in the multiplexed meter reading time slot table; Each of the target energy meters is controlled to acquire energy metering frozen data at the corresponding final uplink start time, which is then encoded as meter reading payload and transmitted via uplink carrier. The meter reading payload is decoded and verified by centralized reception and aggregation, and a data set of electricity meter telemetry data is generated and output to the main station.

2. The method for reading electricity meters based on the Internet of Things according to claim 1, characterized in that, Each of the target energy meters is assigned to a multiplexed meter reading domain, and a power frequency phase synchronization reference is established based on the zero-crossing time of the power frequency on the power supply side of the data concentrator. Additionally, a first pilot subcarrier and a second pilot subcarrier are allocated in the carrier communication band, including: Read the list of meter addresses for each of the target energy meters, and bind the meter addresses with a preset meter reading message format to define the number of symbols required to send the meter reading payload; In the first carrier frame preamble after the zero-crossing moment of the power supply frequency, a first known complex pilot signal is emitted through the first pilot subcarrier, and a second known complex pilot signal is emitted through the second pilot subcarrier; Control each of the target energy meters to synchronously capture the first known complex pilot signal and the second known complex pilot signal.

3. The method for reading electricity meters based on the Internet of Things according to claim 2, characterized in that, Controlling each of the target energy meters to transmit the received pilot signal back as is, in order to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier, including: Short-time loopback trigger commands are sent sequentially to each of the target energy meters according to the ascending order of the table addresses. Each of the target energy meters is controlled to transmit the pilot symbols corresponding to the first known complex pilot signal and the second known complex pilot signal in the same way during two consecutive orthogonal frequency division multiplexing symbols in response to the short-time loopback trigger command; The pilot symbols are demodulated by Fast Fourier Transform, and the first loopback pilot complex sample value and the second loopback pilot complex sample value are extracted at the first pilot subcarrier and the second pilot subcarrier, respectively.

4. The method for reading electricity meters based on the Internet of Things according to claim 3, characterized in that, The group delay tail is calculated based on the first loopback pilot complex sample value and the second loopback pilot complex sample value of each of the target energy meters, including: Channel estimation is performed based on the first loopback pilot complex sample value and the first known complex pilot signal to determine the first equivalent channel response, and channel estimation is performed based on the second loopback pilot complex sample value and the second known complex pilot signal to determine the second equivalent channel response; Extract the complex phase difference between the second equivalent channel response and the first equivalent channel response to obtain the phase frequency response characteristics of the common low-voltage power line path; Phase dewinding is performed on the complex phase difference to eliminate the influence of the phase return boundary, and the group delay tail of each target energy meter is extracted based on the phase difference after dewinding and the frequency interval relationship between the first pilot subcarrier and the second pilot subcarrier.

5. The method for reading electricity meters based on the Internet of Things according to claim 4, characterized in that, Based on this, a multiplexed meter reading time slot table containing the scheduling sequence of each of the target energy meters and the final uplink start time is calculated, including: The tail overflow time is defined based on the portion of the group delay tail that exceeds the preset safe cycle prefix duration. The tail overflow time is compensated for in the time domain by combining the preset symbol stability margin, and the compensated tail overflow time is mapped to an integer multiple span of the duration of a single orthogonal frequency division multiplexing symbol to generate a symbol-level guard interval for isolating inter-symbol interference. The scheduling order of each target energy meter is determined according to the ascending order of the group delay tail of each target energy meter, and the ascending order of the table address is used as an arbitration mechanism under the condition of equality.

6. The method for reading electricity meters based on the Internet of Things according to claim 5, characterized in that, Based on this calculation, a multiplexed meter reading time slot table containing the scheduling sequence of each target energy meter and the final uplink start time is calculated, and also includes: The duration of the power frequency half-cycle is determined based on the power frequency parameters of the power supply network. Based on the final uplink start time of the target energy meter in the prior scheduling sequence, the number of symbols required to send the meter reading payload, and the time-domain sequence of the symbol-level protection interval, the earliest allowed communication start time of the target energy meter in the current scheduling sequence is deduced. Using the zero-crossing moment of the power supply frequency as the time reference anchor point, the earliest allowed communication start time is aligned in the positive direction of the time axis to the midpoint of the first half-cycle of the power frequency, and this is set as the final uplink start time of the target energy meter of the current scheduling sequence to avoid power frequency transient noise. The table address, the final uplink start time, the number of symbols required to send the meter reading payload, and the symbol-level protection interval are fixedly written into the multiplexed meter reading time slot table.

7. The method for reading electricity meters based on the Internet of Things according to claim 6, characterized in that, According to the scheduling sequence in the multiplexed meter reading time slot table, downlink meter reading query frames are sent, and each target energy meter is controlled to acquire energy metering freeze data at the corresponding final uplink start time, which is then encoded into meter reading payload and transmitted via uplink carrier, including: According to the scheduling order in the multiplexed meter reading time slot table, downlink meter reading query frames are sent sequentially before the corresponding final uplink start time arrives. When the final uplink start time arrives, the receive time slot window is opened, and the carrier communication silence is maintained for the duration of the symbol-level guard interval after the receive time slot window ends. The target energy meter is controlled to acquire the energy metering freeze data at the first orthogonal frequency division multiplexing symbol boundary at the final uplink start time. The meter identifier, meter reading, and acquisition time are encoded into the meter reading payload and transmitted uplink. The uplink carrier output is stopped after the number of symbols required to transmit the meter reading payload is completed.

8. The method for reading electricity meters based on the Internet of Things according to claim 7, characterized in that, The meter reading payload is decoded and verified by centralized reception and aggregation, and a data set of electricity meter telemetry data is generated and output to the main station, including: Within the receive time slot window corresponding to the final uplink start time, the received carrier signal is extracted; The carrier signal is sequentially subjected to Fast Fourier Transform, equalization, deinterleaving, channel decoding, and cyclic redundancy check. The meter reading payload that has passed the cyclic redundancy check is mapped to a telemetry data record that includes the electricity meter identifier, the meter reading, and the acquisition time. After processing all the target electricity meters included in the multiplexed meter reading time slot table, the summarized telemetry data is recorded and integrated into the electricity meter metering telemetry dataset, and then transmitted back to the main station via the Internet of Things digital link.

9. An Internet of Things (IoT)-based electricity meter reading system, applied to a common path multiplexing meter reading operation including a data concentrator, multiple target electricity meters, a common low-voltage power line path and a master station, wherein the data concentrator is connected to each of the target electricity meters via the common low-voltage power line path and to the master station via an IoT digital link; The system executes a method for reading electricity meters based on the Internet of Things as described in any one of claims 1-8, characterized in that, The system includes: The reference synchronization and allocation module is used to classify each of the target energy meters into the multiplexed meter reading domain, establish a power frequency phase synchronization reference based on the power frequency zero crossing time of the power supply side of the data concentrator, and allocate the first pilot subcarrier and the second pilot subcarrier in the carrier communication frequency band. The loopback sampling extraction module is used to control each of the target energy meters to transmit the received pilot signal back as is, so as to extract the first loopback pilot complex sample value at the first pilot subcarrier and the second loopback pilot complex sample value at the second pilot subcarrier; The time slot scheduling deduction module is used to deduce the group delay tail based on the first loop back pilot complex sampling value and the second loop back pilot complex sampling value of each target energy meter, and calculate the multiplexed meter reading time slot table including the scheduling order of each target energy meter and the final uplink start time. The query frame sending module is used to send downlink meter reading query frames according to the scheduling sequence in the multiplexed meter reading time slot table; The uplink carrier control module is used to control each of the target energy meters to acquire energy metering frozen data at the corresponding final uplink start time, encode it as meter reading payload and transmit it via uplink carrier; The decoding and aggregation output module is used to decode and verify the meter reading payload through centralized reception and aggregation, and generate and output the electricity meter telemetry dataset to the master station.

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