CN-122001726-A - Channel phase extraction method, system, device and storage medium based on preamble symbol and pilot symbol

CN122001726ACN 122001726 ACN122001726 ACN 122001726ACN-122001726-A

Abstract

The application provides a channel phase extraction method, a system, equipment and a storage medium based on a preamble symbol and a pilot symbol, and relates to the technical field of mobile Internet of things wireless communication. The method comprises the steps of receiving a LoRa signal transmitted by a transmitter of a transmitting end node by a receiver on a gateway, determining a carrier frequency offset and a window time offset by the receiver according to a preamble symbol and a start frame delimiter in the received LoRa signal, performing compensation on the received LoRa signal to eliminate a phase offset caused by the carrier frequency offset and the window time offset, determining a sampling frequency offset according to a spectrum peak interval between adjacent preamble symbols in the compensated signal, performing compensation on the compensated signal to eliminate the phase offset caused by the sampling frequency offset, and obtaining a re-compensated signal And determining the channel phase of the channel of the LoRa signal according to the frequency spectrum peak phases of a plurality of pilot symbols with known code values in the signal after the compensation.

Inventors

WANG JILIANG
LIU XINYI
WU JIE
GAO SHEN

Assignees

中国电信股份有限公司北京云科技研发中心
清华大学

Dates

Publication Date: 20260508
Application Date: 20260112

Claims (10)

1. A method for channel phase extraction based on preamble symbols and pilot symbols, comprising: a receiver on a gateway receives a LoRa signal sent by a sender of a sending end node; The receiver determines carrier frequency offset and window time offset according to a preamble symbol and a start frame separator SFD in a received LoRa signal; The receiver performs compensation on the received LoRa signal to eliminate phase offset caused by the carrier frequency offset and the window time offset, and a compensated signal is obtained; The receiver determines sampling frequency offset according to the spectrum peak value interval between adjacent preamble symbols in the compensated signal; The receiver performs compensation on the compensated signal to eliminate the phase shift caused by the sampling frequency shift to obtain a re-compensated signal The receiver determines the channel phase of the channel transmitting the LoRa signal between the receiver and the transmitter according to the spectrum peak phases of a plurality of pilot symbols with known code values in the re-compensated signal.
2. The method of claim 1, wherein the receiver determining the carrier frequency offset and the window time offset from the preamble symbol and the start frame delimiter SFD in the received LoRa signal comprises: The receiver performs dechirp operations on the preamble symbols in the received LoRa signal, performs fast fourier transform on the result of dechirp operations, and extracts a first frequency corresponding to a spectrum peak value of the preamble symbols; the receiver performs dechirp operations on a start frame separator SFD in the received LoRa signal, performs fast Fourier transform on the dechirp operation result, and extracts a second frequency corresponding to a frequency spectrum peak value of the start frame separator SFD; the receiver obtains carrier frequency offset according to the first frequency and the second frequency; And the receiver obtains window time offset according to the carrier frequency offset and the first frequency.
3. The method of claim 1, wherein the receiver determining a sampling frequency offset based on a spectral peak spacing between adjacent preamble symbols in the compensated signal comprises: The receiver performs dechirp operations on each preamble symbol in the compensated signal, performs fast fourier transform on the result of dechirp operations, and extracts a spectrum peak value of the preamble symbol; For a first preamble symbol and a second preamble symbol of each pair of adjacent preamble symbols, the receiver determines a first time instant corresponding to a spectral peak of the first preamble symbol and a second time instant corresponding to a spectral peak of the second preamble symbol to determine an interval corresponding to the pair of adjacent preamble symbols; the receiver determines an average interval according to intervals corresponding to a plurality of pairs of adjacent preamble symbols; The receiver determining a sampling time offset based on a difference between the average interval and an ideal interval, the ideal interval being determined based on a spreading factor used by the transmitter to generate the LoRa signal; The receiver determines a sampling frequency offset based on the sampling time offset and a sampling rate equal to a bandwidth used by the transmitter to generate the LoRa signal.
4. The method of claim 1, wherein the receiver determining the channel phase of the channel transmitting the LoRa signal between the receiver and the transmitter based on the spectral peak phases of a plurality of previous pilot symbols whose code values are known in the re-compensated signal comprises: the receiver encodes the re-compensated signal to a first value Dechirp, performing fast fourier transform on the result of dechirp operation, and extracting a spectrum peak value of the first target pilot symbol; the receiver encodes the re-compensated signal into a second value Performing dechirp operations on a second target pilot symbol, performing fast fourier transform on the result of dechirp operations, and extracting a spectrum peak value of the second target pilot symbol; The receiver measures a first phase corresponding to a spectral peak of the first target pilot symbol; the receiver measures a second phase corresponding to a spectral peak of the second target pilot symbol; The first equation is satisfied at the first phase: + The second phase satisfies a second equation: + In the case of (2), the receiver solves for an initial phase using the first equation and the second equation And residual window time offset Wherein, the method comprises the steps of, Representing the bandwidth used by the transmitter to generate the LoRa signal, Representing a duration of time used by the transmitter to generate the LoRa signal; The initial phase to be solved by the receiver A channel phase is determined for a channel transmitting the LoRa signal between the receiver and the transmitter.
5. The method according to claim 4, wherein the method further comprises: The receiver solves the initial phase and the residual window time offset corresponding to the pilot symbols with known code values according to the phase of the pilot symbols with known code values; The receiver determines an average initial phase according to initial phases corresponding to pilot symbols with known code values; The initial phase to be solved by the receiver Determining a channel phase for a channel transmitting the LoRa signal between the receiver and the transmitter, comprising: The receiver determines the average initial phase as a channel phase of a channel transmitting the LoRa signal between the receiver and the transmitter.
6. A channel phase extraction system based on preamble symbols and pilot symbols, applied to a gateway, the system comprising: The signal receiving module is used for receiving the LoRa signal sent by the sender of the sending end node; a first offset determining module, configured to determine a carrier frequency offset and a window time offset according to a preamble symbol and a start frame separator SFD in a received LoRa signal; The first compensation module is used for performing compensation on the received LoRa signal so as to eliminate phase offset caused by the carrier frequency offset and the window time offset and obtain a compensated signal; a second offset determining module, configured to determine a sampling frequency offset according to a spectrum peak interval between adjacent preamble symbols in the compensated signal; A second compensation module, configured to perform compensation on the compensated signal by the receiver to eliminate a phase offset caused by the sampling frequency offset, thereby obtaining a compensated signal And the channel phase determining module is used for determining the channel phase of a channel for transmitting the LoRa signal between the receiver and the transmitter according to the spectrum peak phases of a plurality of pilot symbols with known code values in the re-compensated signal.
7. The system of claim 6, wherein the first offset determination module comprises: The first processing module is used for carrying out dechirp operations on the preamble symbols in the received LoRa signal, carrying out fast Fourier transform on the result of dechirp operations, and extracting a first frequency corresponding to a frequency spectrum peak value of the preamble symbols; The second processing module is used for performing dechirp operations on a start frame separator SFD in the received LoRa signal, performing fast Fourier transform on the result of dechirp operations, and extracting a second frequency corresponding to a frequency spectrum peak value of the start frame separator SFD; The third processing module is used for obtaining carrier frequency offset according to the first frequency and the second frequency; And a fourth processing module, configured to obtain a window time offset according to the carrier frequency offset and the first frequency.
8. The system of claim 6, wherein the second offset determination module comprises: A fifth processing module, configured to perform dechirp operations on each preamble symbol in the compensated signal, perform a fast fourier transform on a result of dechirp operations, and extract a spectral peak of the preamble symbol; A first determining module, configured to determine, for a first preamble symbol and a second preamble symbol in each pair of adjacent preamble symbols, a first time corresponding to a spectral peak of the first preamble symbol and a second time corresponding to a spectral peak of the second preamble symbol, so as to determine an interval corresponding to the pair of adjacent preamble symbols; a second determining module, configured to determine an average interval according to intervals corresponding to a plurality of pairs of adjacent preamble symbols; A third determining module configured to determine a sampling time offset based on a difference between the average interval and an ideal interval, the ideal interval being determined based on a spreading factor used by the transmitter to generate the LoRa signal; and a fourth determining module, configured to determine a sampling frequency offset according to the sampling time offset and a sampling rate, where the sampling rate is equal to a bandwidth used by the transmitter to generate the LoRa signal.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the preamble symbol and pilot symbol based channel phase extraction method of any one of claims 1-5 when the computer program is executed.
10. A readable storage medium having stored thereon a computer program, which when executed by a processor performs the steps of the preamble symbol and pilot symbol based channel phase extraction method according to any of claims 1-5.

Description

Channel phase extraction method, system, device and storage medium based on preamble symbol and pilot symbol Technical Field The application relates to the technical field of wireless communication of the mobile internet of things, in particular to a channel phase extraction method, a system, equipment and a storage medium based on a preamble symbol and a pilot symbol. Background In a Long Range (Long Range) network, multiple nodes adopt a random access mechanism, and when multiple nodes send data packets simultaneously, collisions are very easy to occur, resulting in data loss, network throughput degradation and energy waste. Because of the lack of an efficient collision resolution mechanism of the standard LoRa protocol itself, communication reliability poses a serious challenge in application scenarios where nodes are densely deployed. To improve decoding capability under concurrent transmission, related art mainly separates from physical layer characteristics of signals, including methods based on frequency domain, time domain or coding domain. For example, frequency domain-based methods utilize the spectral characteristics of signals, but have poor separation effects when multiple signal frequencies are similar, time domain-based methods rely on signal arrival time differences, and have limited signal processing capability for near synchronous arrival, and code domain methods implement signal identification by assigning unique coding modes to different transmitters, but such schemes generally require modification of the modulation scheme of the transmitting end or the hardware architecture of the receiving end, and are difficult to be compatible with existing widely deployed commercial LoRa devices. On the other hand, the channel characteristics formed by the signals in multipath propagation have spatial uniqueness, and provide new dimensions for distinguishing concurrent signals. Among these, channel phase is one of the key features. However, most of the related channel estimation methods rely on differential measurement among multiple nodes or multiple gateways, only the relative phase difference can be obtained, not only the complexity and the deployment cost of the system are increased, but also the absolute channel phase information of a single node cannot be directly and accurately obtained, and the application of the method in the low-cost and low-complexity internet of things system is limited. Therefore, how to efficiently and accurately extract the channel phase and realize reliable concurrent signal separation is a technical problem to be solved. Disclosure of Invention In view of the above problems, embodiments of the present application provide a method, a system, an apparatus, and a storage medium for extracting a channel phase based on a preamble symbol and a pilot symbol, which can eliminate phase offset caused by a hardware defect and a code content in a process of parallel transmission of a LoRa, accurately recover and extract a channel phase, and can be applied to scenarios such as parallel decoding of the LoRa. In a first aspect of the embodiment of the present application, a method for extracting a channel phase based on a preamble symbol and a pilot symbol is disclosed, where the method includes: a receiver on a gateway receives a LoRa signal sent by a sender of a sending end node; The receiver determines carrier frequency offset and window time offset according to a preamble symbol and a start frame separator SFD in a received LoRa signal; The receiver performs compensation on the received LoRa signal to eliminate phase offset caused by the carrier frequency offset and the window time offset, and a compensated signal is obtained; The receiver determines sampling frequency offset according to the spectrum peak value interval between adjacent preamble symbols in the compensated signal; The receiver performs compensation on the compensated signal to eliminate the phase shift caused by the sampling frequency shift to obtain a re-compensated signal The receiver determines the channel phase of the channel transmitting the LoRa signal between the receiver and the transmitter according to the spectrum peak phases of a plurality of pilot symbols with known code values in the re-compensated signal. Optionally, the receiver determines a carrier frequency offset and a window time offset according to a preamble symbol and a start frame separator SFD in the received LoRa signal, including: The receiver performs dechirp operations on the preamble symbols in the received LoRa signal, performs fast fourier transform on the result of dechirp operations, and extracts a first frequency corresponding to a spectrum peak value of the preamble symbols; the receiver performs dechirp operations on a start frame separator SFD in the received LoRa signal, performs fast Fourier transform on the dechirp operation result, and extracts a second frequency corresponding to a frequency spectrum peak value of the s