Time synchronization method and device for wireless communication

Abstract

The present invention discloses a time synchronization method and device for wireless communication, which belongs to the field of communication technology. The existing technology cannot take into account both accuracy and cost. The present invention provides a time synchronization method for wireless communication, including the following steps: S101: the master and slave devices divide the communication time slots according to the TOD time; S102: the master device initiates a time synchronization service and sends time synchronization information; S103: the slave device receives the time synchronization information, parses the information to obtain the TOD time of the master device and calculates the signal delay, resets the local TOD time, and replies with an ACK signal to the master device; S104: after obtaining the ACK signal, the master device enters a collaborative working mode, regularly sends time synchronization information, and maintains the time synchronization status of the master and slave devices; the present invention takes into account both cost and accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of communications, and in particular to a time synchronization method and device for wireless communications. Background Art

[0002] Wireless communications often utilize various methods, such as spread spectrum, frequency hopping, and orthogonal frequency division multiplexing, where communication frequencies and signal parameters constantly change. To achieve effective communication, the time of departure (TOD) is typically used as the primary variable to determine the frequency and signal parameters between the communicating parties at any given moment.

[0003] Wireless communication involves complex scenarios, making it difficult to obtain accurate TOD times through satellite or network timing. Furthermore, signal transmission delays vary significantly due to varying channel conditions and communication frequency bands, impacting communication quality. Presetting TOD times requires extremely high-precision crystal oscillators to minimize clock drift, significantly increasing hardware costs. Summary of the Invention

[0004] In order to solve one or more of the above-mentioned defects or improvement requirements in the prior art, the present invention provides a time synchronization method for wireless communication, comprising the following steps:

[0005] S101: The master and slave devices divide the communication time slots according to the TOD time;

[0006] S102: The master device initiates a time synchronization service and sends time synchronization information;

[0007] S103: The slave device receives the time synchronization information, parses the information to obtain the TOD time of the master device and calculates the signal delay, resets the local TOD time, and sends an ACK signal to the master device.

[0008] S104.: After receiving the ACK signal, the master device enters the cooperative working mode and regularly sends time synchronization information to maintain the time synchronization status of the master and slave devices.

[0009] Preferably, in the step S101, the master and slave devices divide the time slots at equal intervals based on the TOD time, taking the start time of each natural day as the starting point for time slot division, and τ0 as the time slot length, and then divide the time slot into the first sub-time slot and the second sub-time slot.

[0010] Preferably, the states of the master and slave devices are divided into a time synchronization working mode and a cooperative working mode. In the time synchronization working mode, after receiving the time synchronization instruction, the master device initiates a time synchronization service at the start of the next first sub-time slot, performs time synchronization waveform modulation, and sends time synchronization information on a specified frequency;

[0011] The slave device is on duty at the specified frequency, maintains a data receiving state, and demodulates if a time synchronization waveform is received; if demodulation fails, the slave device continues to be on duty and waits to receive the time synchronization waveform; if demodulation is successful, the time synchronization information is restored from the time synchronization waveform, the TOD information of the master device is obtained, and the information transmission delay is calculated, and the local TOD time and time slot start time are adjusted according to the above information;

[0012] After the adjustment is completed, the slave device divides the time slot according to the newly set TOD time, performs ACK waveform modulation from the second sub-time slot, sends an ACK signal at the specified frequency, and then switches to the receiving mode to receive the master device ACK response signal.

[0013] Within the time range of the second sub-time slot, the master device receives data at the specified frequency and demodulates after receiving the ACK waveform. If the demodulation fails, the master device continues to initiate the time synchronization service at the beginning of the next first sub-time slot. If the demodulation succeeds, the master device replies with an ACK response signal to the slave device and switches to the collaborative working mode.

[0014] After receiving the ACK response signal and successfully demodulating it, the slave device enters the cooperative working mode.

[0015] Preferably, in the collaborative working mode, the master device initiates a time calibration service at the start of the first sub-time slot every m time slots, modulates a time calibration waveform on a specified frequency, and sends time calibration information to the slave device. The slave device is on duty at the specified frequency and demodulates the received time calibration waveform.

[0016] If demodulation fails, the slave device continues to be on duty in the next time slot, waiting to receive the time calibration waveform. If demodulation fails within n consecutive time slots, the slave device returns to the time synchronization working mode. If demodulation succeeds, the slave device adjusts the local TOD time based on the TOD information of the master device obtained and the calculated information transmission delay, and performs ACK waveform modulation at the start of the second sub-time slot, sends an ACK signal on the specified frequency, and continues to maintain the collaborative working mode.

[0017] The master device receives data at the specified frequency within the time range of the second sub-time slot, and demodulates after receiving the ACK waveform; if the demodulation fails, the master device continues to initiate the time calibration service at the beginning of the next first sub-time slot. If the master device fails to successfully demodulate the ACK waveform within n consecutive time slots, it switches to the time synchronization working mode; if the demodulation is successful, it continues to maintain the collaborative working mode.

[0018] Preferably, the method for adjusting the local TOD time and the time slot start time of the slave device includes steps S201-S204:

[0019] S201 uses frame synchronization and symbol timing synchronization to estimate signal delay and obtain an estimated value γ0;

[0020] S202. Taking into account the matched filter delay γ1, the processor DMA module operation delay γ2, the analog-to-digital converter ADC group delay γ3, the signal waveform power rise time TLC delay γ4, etc., the signal delay γ is calculated by the formula γ = γ0-γ1-γ2-γ3-γ4;

[0021] S203. Take the modulus of the signal delay γ and the time slot length τ0 to obtain the clock delay that needs to be adjusted

[0022] S204. Adjust the timer configuration to delay the start time of each time slot calculated based on TOD Complete the time adjustment of the local time slot start time.

[0023] The present invention also provides a wireless communication time synchronization device for implementing the above method, the device comprising an electrically connected antenna, a radio frequency processing module, a baseband processing module, a power supply module and an external interface module;

[0024] The antenna is used to receive and send signals;

[0025] The radio frequency processing module is used to filter, amplify and frequency modulate the radio frequency signal, and achieve time synchronization with the baseband processing module;

[0026] The baseband processing module is used to store and process radio frequency signals and achieve time synchronization together with the radio frequency processing module;

[0027] The power supply module is used to provide power to the antenna, the radio frequency processing module, the baseband processing module and the external interface module;

[0028] The external interface module is used for external communication.

[0029] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0030] (1) The present invention provides a time synchronization method and device for wireless communication. The master device initiates a time synchronization service and sends time synchronization information to the slave device. The slave device adjusts the local TOD time based on the received time synchronization information. After the master device confirms the ACK information replied by the slave device, it enters the coordination phase and replies an ACK response to the slave device. During the coordination phase, the master device periodically sends time synchronization information to maintain the time synchronization status of the master and slave devices. Through the above steps, the time synchronization status of the master and slave devices in the system can still be guaranteed under the conditions of lack of external device timing, different signal delays between different devices in the system, and low crystal oscillator accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is a flow chart of a time synchronization method for wireless communication provided by an embodiment of the present invention;

[0032] Figure 2 A time slot division method for a time synchronization method for wireless communication provided by an embodiment of the present invention;

[0033] Figure 3 This is a master-slave device time synchronization process of a wireless communication time synchronization method provided by an embodiment of the present invention;

[0034] Figure 4 This is a data waveform frame format of a time synchronization method for wireless communication provided by an embodiment of the present invention;

[0035] Figure 5 This is a data unit format of a time synchronization method for wireless communication provided by an embodiment of the present invention;

[0036] Figure 6 This is a time slot start time correction process of a time synchronization method for wireless communication provided by an embodiment of the present invention;

[0037] Figure 7 This is a structural block diagram of a time synchronization device for wireless communication provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0039] Example:

[0040] like Figure 1As shown, in one embodiment, the present invention provides a time synchronization method for wireless communication, including steps S101-S104:

[0041] S101 master and slave devices divide communication time slots according to TOD time;

[0042] S102. The master device initiates a time synchronization service and sends time synchronization information;

[0043] S103. The slave device receives time synchronization information, parses the information to obtain the TOD time of the master device and calculates the signal delay, resets the local TOD time and the time slot start time, and replies to the master device with an ACK signal;

[0044] S104. After the master device obtains the ACK signal and successfully parses it, it enters the collaboration phase and regularly sends time synchronization information to maintain the time synchronization status of the master and slave devices.

[0045] In the above step S101, the master and slave devices divide the communication time slots according to the TOD time. The specific method is as follows: Figure 2 shown.

[0046] The master and slave devices divide the time slots into equal intervals based on the TOD time, with the start of each natural day as the starting point, and τ0 as the time slot length. The time slots are then divided into sub-slot 1 and sub-slot 2.

[0047] According to the different states of the devices, it is divided into the time synchronization stage and the collaborative work stage.

[0048] The master-slave device time synchronization process in the time synchronization phase and the collaborative working phase is as follows: Figure 3 shown.

[0049] In the time synchronization phase, after receiving the time synchronization instruction, the master device initiates the time synchronization service at the start of the next sub-time slot 1, performs time synchronization waveform modulation, and sends the time synchronization information on the specified frequency.

[0050] The slave device maintains data reception at the designated frequency and demodulates the received time synchronization waveform. If demodulation fails, the slave device continues to wait for the received time synchronization waveform. If demodulation succeeds, it recovers the time synchronization information from the waveform, obtains the master device's time-of-departure (TOD) information, calculates the information transmission delay, and adjusts the local TOD time and time slot start time based on this information.

[0051] After the adjustment is completed, the slave device divides the time slot according to the newly set TOD time. At the beginning of sub-time slot 2, it modulates the ACK waveform and sends the ACK signal at the specified frequency. It then switches to the receiving mode and receives the ACK response signal from the master device.

[0052] During sub-timeslot 2, the master device receives data at the specified frequency and demodulates after receiving the ACK waveform. If demodulation fails, the master device continues to initiate time synchronization services at the start of the next sub-timeslot 1. If demodulation succeeds, the master device sends an ACK response signal to the slave device and switches to collaborative working mode.

[0053] After receiving the ACK response signal and successfully demodulating it, the slave device enters the collaborative working mode stage.

[0054] In the collaborative working mode, the master device initiates the time calibration service every m time slots at the beginning of sub-time slot 1, modulates the time calibration waveform on the specified frequency, and sends the time calibration information to the slave device. The slave device is on duty at the specified frequency and demodulates the received time calibration waveform.

[0055] If demodulation fails, the slave device continues to be on duty in the next time slot, waiting to receive the time calibration waveform. If demodulation fails within n consecutive time slots, the slave device returns to the time synchronization stage. If demodulation succeeds, the slave device adjusts the local TOD time based on the TOD information obtained from the master device and the calculated information transmission delay, and at the beginning of sub-time slot 2, it modulates the ACK waveform and sends the ACK signal on the specified frequency, while continuing to maintain the collaborative working mode.

[0056] The master device receives data at the specified frequency within the time range of sub-timeslot 2 and demodulates after receiving the ACK waveform. If demodulation fails, the master device continues to initiate the time calibration service at the beginning of the next sub-timeslot 1. If the master device fails to successfully demodulate the ACK waveform within n consecutive time slots, it switches to the time synchronization phase. If demodulation succeeds, it continues to maintain the collaborative working mode.

[0057] In one embodiment, Figure 4 As shown, the time synchronization information and time calibration information have a unified data waveform frame format. The data waveform frame format consists of 336 symbols, carrying a total of 22 bytes of data information, including 48 symbols for the Transmit Level Control (TLC) section, 112 symbols for the Preamble section, and 176 symbols for the Data section. The Preamble section consists of a 112-symbol known QPSK sequence with good autocorrelation, and is primarily used for signal synchronization and channel parameter estimation.

[0058] The composition of the QPSK known sequence symbols in one embodiment is shown in the following table.

[0059]

[0060]

[0061] In one embodiment, the ACK data waveform frame format is as follows: Figure 4 As shown, it consists of 112 symbols, of which the TLC is 48 symbols and the ACK data part is 64 symbols, which are used to feedback whether the data frame is received successfully.

[0062] An ACK symbol mapping table of an embodiment is shown in the following table.

[0063]

[0064]

[0065] In one embodiment, the symbol rate of the data waveform is 1200 symbols / second, the digital modulation method is QPSK modulation, and the intermediate frequency carrier is 1800 Hz.

[0066] In one embodiment, Figure 5 As shown, the time synchronization information data unit load 22 bytes of information (176 bits), including a protocol header, a data packet identification ID, a local address, a peer address, a date, a time, a CRC check word, etc.; the time calibration information data unit load 22 bytes of information (176 bits), including a protocol header, a data packet identification ID, a peer address, a link ID, a date, a time, a CRC check word, etc.

[0067] In one embodiment, coarse synchronization is used to perform frame synchronization on signal frames, and a search interval for fine synchronization is determined. Fine synchronization is used to perform symbol timing synchronization, and the signal delay γ0 is accurately estimated within the search interval.

[0068] In the coarse synchronization process, a zero-phase filter is used to perform matched filtering on the received signal, and then a sliding time window is used to sample and obtain intermediate parameters and perform likelihood function calculation. When the likelihood function value exceeds the synchronization decision threshold, a peak search is performed on the likelihood function value to determine the search interval for fine synchronization;

[0069] In the fine synchronization process, an iterative search is performed within the search interval, and a matched filter of the group delay is generated based on the estimated delay value. After the received signal is compensated, it is measured using a least squares approximation function. At the same time, Gaussian interpolation is used in the iterative process to obtain accurate estimation results, thereby improving the search speed and reducing the number of iterations.

[0070] The method for adjusting the local TOD time and time slot start time of the slave device is as follows: Figure 6 As shown, the steps S201-S204 are included:

[0071] S201 uses frame synchronization and symbol timing synchronization to estimate signal delay and obtain an estimated value γ0;

[0072] S202. Taking into account the matched filter delay γ1, the processor DMA module operation delay γ2, the analog-to-digital converter ADC group delay γ3, the signal waveform power rise time TLC delay γ4, etc., the signal delay γ is calculated by the formula γ = γ0-γ1-γ2-γ3-γ4;

[0073] S203. Take the modulus of the signal delay γ and the time slot length τ0 to obtain the clock delay that needs to be adjusted

[0074] S204. Adjust the timer configuration to delay the start time of each time slot calculated based on TOD Complete the time adjustment of the local time slot start time.

[0075] In another embodiment, Figure 6 As shown, the present invention provides a wireless communication time synchronization device capable of implementing any of the above processing methods, including an antenna, a radio frequency processing module, a baseband processing module, a power supply module and an external interface module electrically connected in sequence.

[0076] The antenna needs to be adapted to the communication frequency band in which the device actually operates;

[0077] The RF processing module includes components such as a RF switch, a bandpass filter, a low noise amplifier, a mixer, an intermediate frequency filter, a frequency synthesizer, an orthogonal modem, a clock crystal oscillator, a buffer and a power amplifier;

[0078] The baseband processing module includes components such as digital signal processing, memory, A / D converter, D / A converter, balanced / unbalanced converter, etc.

[0079] The power supply module needs to generate a suitable voltage to support the operation of each module and provide sufficient power;

[0080] The external interface module supports serial interfaces such as I2C, SPI, and UART, high-speed interfaces such as USB and Ethernet, and wireless communication interfaces such as Bluetooth and WLAN.

[0081] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A time synchronization method for wireless communication, comprising the following steps: S101: The master and slave devices divide the communication time slots according to the TOD time; S102: The master device initiates a time synchronization service and sends time synchronization information; S103: The slave device receives the time synchronization information, parses the information to obtain the TOD time of the master device and calculates the signal delay, resets the local TOD time, and sends an ACK signal to the master device. S104: After receiving the ACK signal, the master device enters a collaborative working mode and regularly sends time synchronization information to maintain the time synchronization status of the master and slave devices; The method for adjusting the local TOD time and the time slot start time of the slave device includes steps S201-S204: S201 uses frame synchronization and symbol timing synchronization to estimate signal delay and obtain an estimated value γ0; S202. Taking into account the matched filter delay γ1, the processor DMA module operation delay γ2, the analog-to-digital converter ADC group delay γ3, and the signal waveform power rise time TLC delay γ4, the signal delay γ is calculated by the formula γ = γ0-γ1-γ2-γ3-γ4; S203. The signal delay γ is modulo the time slot length τ0 to obtain the clock delay that needs to be adjusted; S204. Adjust the timer configuration to delay the start time of each time slot calculated based on the TOD to complete the time adjustment of the local time slot start time.

2. The synchronization method according to claim 1, wherein: In step S101, the master and slave devices divide the time slots into equal intervals based on the TOD time, taking the start of each natural day as the starting point for time slot division, and τ0 as the time slot length, and then divide the time slot into the first sub-time slot and the second sub-time slot.

3. The synchronization method according to claim 2, wherein: The states of the master and slave devices are divided into a time synchronization working mode and a collaborative working mode. In the time synchronization working mode, after receiving the time synchronization instruction, the master device initiates a time synchronization service at the beginning of the next first sub-time slot, performs time synchronization waveform modulation, and sends time synchronization information on a specified frequency; The slave device is on duty at the specified frequency, maintains a data receiving state, and demodulates if a time synchronization waveform is received; if demodulation fails, the slave device continues to be on duty and waits to receive the time synchronization waveform; if demodulation is successful, the time synchronization information is restored from the time synchronization waveform, the TOD information of the master device is obtained, and the information transmission delay is calculated, and the local TOD time and time slot start time are adjusted according to the above information; After the adjustment is completed, the slave device divides the time slot according to the newly set TOD time, and starts from the second sub-time slot, performs ACK waveform modulation, sends the ACK signal at the specified frequency, and then switches to the receiving mode to receive the ACK response signal of the master device; During the second sub-time slot, the master device receives data at a specified frequency and demodulates the data after receiving the ACK waveform. If demodulation fails, the master device continues to initiate the time synchronization service at the beginning of the next first sub-time slot. If demodulation succeeds, it replies with an ACK response signal to the slave device and switches to collaborative working mode. After receiving the ACK response signal and successfully demodulating it, the slave device enters the cooperative working mode.

4. The synchronization method according to claim 3, wherein: In collaborative working mode, the master device initiates a time calibration service at the start of the first sub-time slot every m time slots, modulates a time calibration waveform on a specified frequency, and sends the time calibration information to the slave device. The slave device is on duty at the specified frequency and demodulates the received time calibration waveform. If demodulation fails, the slave device continues to be on duty in the next time slot, waiting to receive the time calibration waveform. If demodulation fails within n consecutive time slots, the slave device returns to the time synchronization working mode. If demodulation succeeds, the slave device adjusts the local TOD time based on the TOD information of the master device obtained and the calculated information transmission delay, and performs ACK waveform modulation at the start of the second sub-time slot, sends an ACK signal on the specified frequency, and continues to maintain the collaborative working mode. The master device receives data at a specified frequency within the time range of the second sub-time slot and demodulates the data after receiving the ACK waveform; If demodulation fails, the master device continues to initiate the time calibration service at the beginning of the next first sub-time slot. If the master device fails to successfully demodulate the ACK waveform within n consecutive time slots, it switches to the time synchronization working mode; if demodulation is successful, it continues to maintain the collaborative working mode.

5. A wireless communication time synchronization device for implementing the method according to any one of claims 1 to 4, characterized in that: The device includes an electrically connected antenna, a radio frequency processing module, a baseband processing module, a power supply module and an external interface module; The antenna is used to receive and send signals; The radio frequency processing module is used to filter, amplify and frequency modulate the radio frequency signal, and achieve time synchronization with the baseband processing module; The baseband processing module is used to store and process radio frequency signals and achieve time synchronization with the radio frequency processing module; The power supply module is used to provide power to the antenna, the radio frequency processing module, the baseband processing module and the external interface module; The external interface module is used for external communication.

Images