A method and apparatus for master-slave time synchronization

Abstract

This invention relates to a method and apparatus for master-slave time synchronization. The master and slave devices of this invention store the same timing correspondence table. The slave device compares the demodulated timing with the actual timing to determine whether the carrier is being interfered with, and determines whether the carrier frequency needs to be changed in real time based on the interference situation. When the TDD DL timing is within the allowable range, the slave device can generate uplink and downlink timing consistent with the master device by looking up the table, which solves the problems of traditional time synchronization methods being susceptible to interference and timing inconsistencies between master and slave devices.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, and more particularly to a method and apparatus for master-slave time synchronization. Background Technology

[0002] The 5G era will be an era of interconnectedness. 5G technology will permeate all industries, profoundly impacting people's social lives and work styles. Statistics show that in the 5G era, 85% of data traffic will occur indoors, making good indoor signal coverage a core competitive advantage for operators.

[0003] Due to building obstructions, the complexity of the urban environment, and the large loss of 5G frequency bands in the air propagation and penetration, there are weak coverage and blind coverage scenarios indoors, such as underground parking lots, elevator shafts, business halls, supermarkets, KTVs and cafes.

[0004] One current approach to addressing the aforementioned weak and blind coverage areas is to use wireless repeaters. This involves coupling a wireless signal from the source base station, filtering and amplifying it, and then introducing the signal into the weak or blind area. To further extend or enhance coverage, a master-slave mode is used in these repeaters. The master repeater couples the wireless signal from the source base station, filters and amplifies it, and then transmits it to the slave repeater. The slave repeater receives the signal from the master repeater and amplifies it in turn.

[0005] In master-slave mode, time synchronization is required between the master and slave devices when using TDD (Time Division Duplexing) duplex technology. Currently, one method for master-slave time synchronization is OOK (On-Off Keying). This method involves the master modulating the downlink timing onto a specific carrier frequency, and the slave demodulating the downlink timing from that carrier frequency, thus achieving master-slave time synchronization. However, this method has the following drawbacks:

[0006] (1) Currently, a single carrier frequency is used. When the carrier frequency is interfered with, the downlink timing demodulated by the slave device does not match the actual timing, resulting in chaotic uplink and downlink switching of the slave device. This makes it impossible for the terminals in the slave device's coverage area to perform services normally, which seriously affects the user experience.

[0007] (2) The slave device recovers the downlink timing from the OOK signal only by detection. Since OOK is essentially an ASK (Amplitude Shift Keying) mode, and amplitude modulation is sensitive to signal strength, when the OOK signal received by the slave device is strong or weak, the recovered downlink timing time will be longer or shorter, resulting in the recovered timing being inconsistent with the timing of the master device. When the uplink and downlink timings between the masters are seriously inconsistent or the uplink and downlink timings overlap, the terminals will be unable to communicate normally. Summary of the Invention

[0008] To address the issues of interference susceptibility and single-point failure in traditional OOK (Out-of-Know) methods using a single carrier frequency, and the inconsistency between the uplink and downlink timings of the slave and master devices due to varying OOK signal strength in traditional time synchronization methods, a master-slave time synchronization method and apparatus are proposed.

[0009] To achieve the above objectives, a method for master-slave time synchronization includes the following steps:

[0010] S1: Obtain the TDD uplink / downlink time slot ratio and special subframe format information, and generate a frame synchronization indicator; obtain the table index i, TDD DL timing time, TDD UL timing time, first conversion point switching time SW1 and second conversion point switching time SW2 by querying the timing relationship correspondence table;

[0011] S2: Generate the host's TDD uplink / downlink switching timing based on the acquired TDD DL timing time, TDD UL timing time, first switch point switching time SW1, second switch point switching time SW2, and frame synchronization indication;

[0012] S3: Generate carrier frequency point, and perform OOK modulation on the carrier frequency point to generate OOK signal;

[0013] S4: Amplify and filter the generated OOK signal and send it to the slave device. At the same time, send the carrier frequency and table index i to the slave device.

[0014] S5: The slave device switches to the filter channel corresponding to the carrier frequency.

[0015] S6: Demodulate the TDD DL timing from the transmitted OOK signal, periodically sample the demodulated TDD DL timing, obtain the demodulated TDD DL timing time Ts, and obtain the TDD DL timing time Te corresponding to the transmitted table index i by querying the timing relationship correspondence table.

[0016] S7: Calculate the difference Δ between Ts and Te, and determine whether |Δ|≤δ, where δ is the allowable range and δ is a positive value. If yes, proceed to S8; otherwise, send a timing regeneration failure message to the host and proceed to S3.

[0017] S8: Query the timing relationship table through table index i to obtain TDD DL timing time, TDD UL timing time, first conversion point switching time SW1, second conversion point switching time SW2 and frame header offset, and generate the slave's TDD uplink and downlink switching timing;

[0018] The timing relationship correspondence table includes table index i, where i is a positive integer, uplink / downlink time slot ratio, special subframe format, frame header offset, TDD DL timing time, first conversion point switching time SW1, TDD UL timing time, and second conversion point switching time SW2.

[0019] Table index i is unique and is a positive integer. Each table index i corresponds to different uplink / downlink time slot ratios, special subframe formats, frame header offsets, TDD DL timing times, first conversion point switching time SW1, TDD UL timing times, and second conversion point switching time SW2.

[0020] The timing relationship mapping table stored by the master and slave devices is a synchronization table. When the timing relationship mapping table changes, the master needs to send the changed timing relationship mapping table to the slave device so that the master and slave devices can keep in consistency.

[0021] The frame header offset is X, which is non-zero. If X is positive, the slave device will move the entire TDD uplink and downlink timing forward by Xns after receiving the rising edge of the OOK signal. If X is negative, the slave device will move the entire TDD uplink and downlink timing backward by Xns after receiving the rising edge of the OOK signal.

[0022] When the master receives multiple timing regeneration failure messages reported by slave devices, the majority principle can be used to switch the carrier frequency. That is, the master will only switch the carrier frequency when there are ≥2 slave devices reporting timing regeneration failure messages.

[0023] A master-slave time synchronization device includes a master and at least one slave. The master includes a source synchronization module, a frequency generation module, an OOK modulation module, a transmission module, a master control module, a master communication module, a master combiner, and a master antenna.

[0024] The source synchronization module is used to acquire the TDD uplink and downlink time slot ratio and special subframe format information, and at the same time outputs the frame synchronization indication to the control module;

[0025] The host control module is used to generate the host's TDD uplink / downlink switching timing and to control the frequency generation module to generate carrier frequency points and send the carrier frequency points to the OOK modulation module.

[0026] The host control module is used to control the OOK modulation module to perform OOK modulation on the carrier frequency to generate an OOK signal, and then send the OOK signal to the transmission module.

[0027] The transmitting module is used to amplify and filter the OOK signal before sending it to the host combiner;

[0028] The host combiner is used to combine the OOK signal and the communication signal and then send them to the host antenna.

[0029] The master antenna transmits the received OOK signal and communication signal to the slave device;

[0030] The control module sends the table index i, carrier frequency point and timing relationship correspondence table to the communication module. The communication module is used to exchange the table index i, carrier frequency point and timing relationship correspondence table between the master and slave.

[0031] The slave device includes a slave antenna, a slave combiner, a frequency selection module, a level control module, a demodulation module, a timing regeneration module, a slave communication module, and a slave control module;

[0032] The slave antenna is used to receive OOK signals and communication signals and send them to the slave combiner;

[0033] The slave combiner is used to separate the OOK signal and the communication signal, and sends the OOK signal to the frequency selection module;

[0034] The slave communication module is used to receive the table index i, carrier frequency point and timing relationship correspondence table sent by the master, and send it to the slave control module;

[0035] The slave control module controls the frequency selection module to switch to the filtering channel corresponding to the carrier frequency point according to the carrier frequency point sent by the master, and filters the OOK signal;

[0036] The slave control module controls the level control module to control the power of the OOK signal;

[0037] The demodulation module is used to demodulate the TDD DL timing from the OOK signal, and then send the timing to the timing regeneration module;

[0038] The timing regeneration module is used to determine whether the timing of TDD DL is within the tolerance range, and to perform subsequent processing on the determination result;

[0039] The level control module includes an adjustable attenuator and a power amplifier (PA), with the adjustable attenuator connected to the PA.

[0040] The adjustable attenuator achieves signal power attenuation on the link through a control module.

[0041] PA is used to amplify signals on the link.

[0042] The frequency selection module includes a first single-pole multi-throw switch, a second single-pole multi-throw switch, and several bandpass filters. The bandpass filters are arranged in parallel, and the two ends of each bandpass filter are respectively connected to the switch contacts of the first single-pole multi-throw switch and the second single-pole multi-throw switch.

[0043] The first single-pole multi-throw switch and the second single-pole multi-throw switch are used to control the switch to switch to the corresponding channel according to the carrier frequency sent by the host.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] This invention determines whether the carrier is interfered by comparing the demodulated timing sequence with the actual timing sequence, and decides whether to change the carrier frequency in real time based on the interference situation to ensure master-slave time synchronization. This avoids the single point of failure problem caused by the traditional OOK method using a single carrier frequency. The master and slave devices in this invention maintain the same timing correspondence table, with each table index having a unique corresponding timing relationship. Each slave device can generate uplink and downlink timing sequences consistent with the master device by looking up the table, avoiding the problem of inconsistent uplink and downlink timing sequences between slave devices and the master device caused by different OOK signal strengths in traditional time synchronization methods. This invention enables master-slave time synchronization, extends the signal coverage area, enhances coverage effect, and improves user experience. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0047] Figure 1 This is a flowchart of a master-slave time synchronization method provided by the present invention;

[0048] Figure 2 This invention provides a TDD uplink / downlink timing switching diagram;

[0049] Figure 3 This is a schematic diagram of a host device provided by the present invention;

[0050] Figure 4 This is a schematic diagram of a slave device provided by the present invention;

[0051] Figure 5 This is a schematic diagram of a frequency selection module provided by the present invention;

[0052] Figure 6 This is a schematic diagram of a level control module provided by the present invention;

[0053] Figure 7 This is a schematic diagram of a one-master-four-slave networking system provided in an embodiment of the present invention. Detailed Implementation

[0054] The present invention will be further described below with reference to the accompanying drawings:

[0055] See Figure 1 A method for master-slave time synchronization includes the following steps:

[0056] S1: The host's source synchronization module achieves time synchronization and frame synchronization with the source base station through the cell search process, and obtains the TDD uplink and downlink time slot ratio and special subframe format information by parsing the base station's system messages, while generating a frame synchronization indication for the control module.

[0057] S2: The host's control module obtains the table index i by querying the timing relationship correspondence table based on the parsed TDD uplink and downlink time slot ratio and special subframe format information. i is a positive integer, and includes the TDD DL (Downlink) timing time, TDD UL (Uplink) timing time, first conversion point switching time SW1, and second conversion point switching time SW2.

[0058] Furthermore, the timing relationship correspondence table includes table index i, uplink / downlink time slot ratio, special subframe format, frame header offset, TDD DL timing time, first conversion point switching time SW1, TDD UL timing time, and second conversion point switching time SW2;

[0059] Furthermore, the table index is unique and is a positive integer. Each table index i corresponds to different uplink / downlink time slot ratios, special subframe formats, frame header offsets, TDD DL timing times, first conversion point switching time SW1, TDD UL timing times, and second conversion point switching time SW2.

[0060] Furthermore, the timing relationship mapping table stored by the master and slave is the same table. When the timing relationship mapping table changes, the master needs to send the changed timing relationship mapping table to the slave so that the master and slave can be consistent.

[0061] The timing relationship correspondence table includes an index, uplink / downlink time slot ratio, special subframe format, frame header offset, TDD DL timing time, first conversion point switching time SW1, TDD UL timing time, and second conversion point switching time SW2.

[0062] To further illustrate the time-series relationship mapping table, we will use index 6 as an example:

[0063] The uplink and downlink time slot ratio is DD DD DD DS UU, with a single cycle of 5ms; where D represents the downlink time slot; S represents the special time slot; and U represents the uplink time slot.

[0064] The special subframe format is DW:GP:UP = 6:4:4; DW is 6, which means it occupies 6 symbols; GP is 4, which means it occupies 4 symbols; UP is 4, which means it occupies 4 symbols.

[0065] The frame header offset is used to adjust the slave timing frame header offset, that is, to shift the entire TDD uplink and downlink timing of the slave forward or backward. Here, the value is 0ns, which means that the slave does not need to adjust the frame header offset.

[0066] The DL timing time is the duration of the DL operation, which is 3717μs here, meaning that the downlink will last for 3717μs.

[0067] SW1 is the transition point from the end of DL to the start of UL, which is 3μs in this case. This means that after DL is closed, UL will be opened after a 3μs delay.

[0068] UL timing time is the duration of UL, which is 1277μs here, meaning the uplink will last for 1277μs.

[0069] SW2 is the transition point from the end of UL to the start of DL, which is 3μs in this case. This means that after UL is closed, DL will be opened after a 3μs delay.

[0070] S3: The host's control module generates the host's TDD uplink / downlink switching timing based on the TDD DL timing time, TDD UL timing time, first switching point switching time SW1, second switching point switching time SW2, and frame synchronization indication obtained from the query timing relationship correspondence table;

[0071] To further illustrate the host's TDD uplink / downlink handover timings:

[0072] Assuming the table index is 6, based on the query time series relationship correspondence table (see Table 1), the obtained TDD DL time series time, TDD UL time series time, first transition point switching time SW1, and second transition point switching time SW2 are as follows:

[0073] TDD DL timing time: 3717μs

[0074] TDD UL timing time: 1277μs

[0075] First switching point switching time SW1: 3μs

[0076] Second switching point switching time SW2: 3μs

[0077] After receiving the frame synchronization instruction, the control module opens DL and closes it after 3717μs. After DL is closed for 3μs, it opens UL and closes it after 1277μs. After UL is closed for 3μs, it opens DL. One cycle lasts for a total of 5ms.

[0078] S4: The host frequency generation module generates a carrier frequency point Fn, where n is a positive integer. The control module controls the modulation module to perform OOK modulation on the carrier frequency point to generate an OOK signal based on the frame synchronization indication, the TDD DL timing time obtained from the lookup table, the TDD UL timing time, the first conversion point switching time SW1, and the second conversion point switching time SW2.

[0079] To further illustrate the modulation process of the OOK signal:

[0080] Assuming the table index is 6, based on the query time series relationship correspondence table (see Table 1), the obtained TDD DL time series time, TDD UL time series time, first transition point switching time SW1, and second transition point switching time SW2 are as follows:

[0081] TDD DL timing time: 3717μs

[0082] TDD UL timing time: 1277μs

[0083] First switching point switching time SW1: 3μs

[0084] Second switching point switching time SW2: 3μs

[0085] After receiving the frame synchronization instruction, the control module activates DL and performs OOK On modulation on the carrier frequency for a duration of 3717 μs (DL timing time). After On modulation ends, it performs OOK Off modulation on the carrier frequency for a duration equal to the sum of TDD UL timing time, the first switching point switching time SW1, and the second switching point switching time SW2, which is 1283 μs. Each cycle is DL + UL = 3717 μs + 1283 μs = 5000 μs.

[0086] S5: The host's transmitting module amplifies and filters the generated OOK signal and sends it to the slave through the antenna. At the same time, it sends the carrier frequency and table index i to the slave through the communication module.

[0087] S6: The slave control module controls the frequency selection module to switch to the filter channel corresponding to the carrier frequency according to the carrier frequency sent by the master.

[0088] To further illustrate the switching of the filter channels in the frequency selection module, see [link to relevant documentation]. Figure 5 :

[0089] If the slave control module receives a carrier frequency of F1 from the master, the control module controls the frequency selection module to switch the filter channel to the channel corresponding to F1.

[0090] If the slave control module receives a carrier frequency of F2 from the master, the control module controls the frequency selection module to switch the filter channel to the channel corresponding to F2.

[0091] If the slave control module receives a carrier frequency of F3 from the master, the control module controls the frequency selection module to switch the filter channel to the channel corresponding to F3.

[0092] S7: The demodulation module of the slave device demodulates the TDD DL timing from the OOK signal and then sends the timing to the timing regeneration module;

[0093] S8: The timing regeneration module of the slave device periodically samples the demodulated TDD DL timing to obtain the demodulated TDD DL timing time Ts;

[0094] S9: The slave timing regeneration module obtains the TDD DL timing time Te corresponding to the table index i sent by the master by querying the timing relationship correspondence table;

[0095] S10: The timing regeneration module of the slave device calculates the difference between Ts and Te, that is, the difference Δ = Ts - Te;

[0096] S11: The timing regeneration module of the slave device determines whether Δ is within the allowable range δ (a positive value), i.e., |Δ|≤δ; if yes, it queries the timing relationship correspondence table through table index i to obtain the TDD DL timing time, TDD UL timing time, first transition point switching time SW1, second transition point switching time SW2, and frame header offset; if no, it sends a timing regeneration failure message to the master device through the communication module.

[0097] Furthermore, the timing regeneration module first sends a timing regeneration failure message to the control module, and the control module sends the timing regeneration failure message to the host through the communication module.

[0098] S12: The timing regeneration module of the slave device generates the TDD uplink and downlink switching timing of the slave device based on the TDD DL timing time, TDD UL timing time, first transition point switching time SW1, second transition point switching time SW2 and frame header offset obtained from the lookup table;

[0099] To further illustrate the TDD uplink / downlink handover timing of the slave device:

[0100] Table 1. Timing Relationship Correspondence Table

[0101]

[0102] Assuming the table index is 6, based on the query timing relationship correspondence table (see Table 1), the obtained TDD DL timing time, TDD UL timing time, first transition point switching time SW1, second transition point switching time SW2, and frame header offset are as follows:

[0103] TDD DL timing time: 3717μs

[0104] TDD UL timing time: 1277μs

[0105] First switching point switching time SW1: 3μs

[0106] Second switching point switching time SW2: 3μs

[0107] Frame header offset: 0ns

[0108] After receiving the rising edge of the OOK signal, the control module turns on DL and turns it off after 3717μs. After DL is turned off for 3μs, UL is turned on and turns off after 1277μs. After UL is turned off for 3μs, DL is turned on.

[0109] Furthermore, the frame header offset is X (non-zero); if X is positive, the timing regeneration module will move the entire TDD uplink and downlink timing forward by Xns after receiving the rising edge of the OOK signal; if X is negative, the timing regeneration module will move the entire TDD uplink and downlink timing backward by Xns after receiving the rising edge of the OOK signal.

[0110] S13: If the master communication module receives a timing regeneration failure message from the slave, the control module controls the frequency generation module to generate a new carrier frequency (Fm, m≠n), uses the new carrier frequency to generate an OOK signal, and sends the new carrier frequency to the slave. The slave then demodulates the OOK signal, resamples, recalculates the difference Δ, and makes a judgment.

[0111] A master-slave time synchronization device includes a master and a slave.

[0112] See Figure 3 :

[0113] The host computer mainly performs the following functions:

[0114] (1) The source synchronization module achieves time synchronization and frame synchronization with the source base station through the cell search process, and obtains the TDD uplink and downlink time slot ratio and special subframe format information by parsing the base station system message, and outputs the frame synchronization indication to the control module.

[0115] (2) The TDD uplink and downlink switching timing of the host is generated based on the TDD DL timing time, TDD UL timing time, first switching point switching time SW1, second switching point switching time SW2 and frame synchronization indication obtained from the query timing relationship correspondence table;

[0116] (3) Based on the TDD DL timing time, TDD UL timing time, first switching point switching time SW1 and second switching point switching time SW2 obtained from the query timing relationship correspondence table, and the frame synchronization indication, the carrier is modulated to generate an OOK signal;

[0117] (4) Send the currently used carrier frequency and table index to the slave device. When the carrier frequency and table index change, send the changed carrier frequency and table index to the slave device.

[0118] (5) Switch to a new carrier frequency point based on the timing regeneration failure message reported by the slave device;

[0119] (6) Save the timing relationship correspondence table and synchronize the table to the slave. When the timing relationship correspondence table of the master changes, the changed table must be synchronized to the slave so that the timing relationship correspondence tables saved by the master and the slave are consistent.

[0120] The main unit includes a source synchronization module, a frequency generation module, an OOK modulation module, a transmission module, a main unit control module, a main unit communication module, a main unit combiner, and a main unit antenna.

[0121] The frequency generation module is used to generate carrier frequency points and is connected to the OOK modulation module and the host control module;

[0122] The OOK modulation module is used to generate an OOK signal based on the TDD DL timing time, TDD UL timing time, first conversion point switching time, second conversion point switching time, and frame synchronization indication, and is connected to the transmitter module and the host control module.

[0123] The transmitting module is used to amplify and filter the OOK signal and is connected to the host combiner;

[0124] The source synchronization module is used to achieve time synchronization and frame synchronization with the source base station through the cell search process, and obtains the TDD uplink and downlink time slot ratio and special subframe format information by parsing the base station system messages, while outputting the frame synchronization indication to the host control module.

[0125] The host communication module enables communication with the slave device, and is used to exchange information such as carrier frequency point, table index and timing relationship correspondence table with the slave device. The host communication module connects the host control module and the host combiner.

[0126] The main combiner is used for combining / splitting OOK signals and communication signals, and the main combiner is connected to the main antenna;

[0127] The main antenna is used to receive and transmit OOK signals and communication signals;

[0128] The host control module mainly performs the following functions:

[0129] (1) The control frequency generation module generates carrier frequency points and switches carrier frequency points according to the timing regeneration failure message reported by the slave device;

[0130] (2) The TDD uplink and downlink switching timing of the host is generated based on the TDD DL timing time, TDD UL timing time, first switching point switching time SW1, second switching point switching time SW2 and frame synchronization indication obtained from the query timing relationship correspondence table;

[0131] (3) Based on the TDD DL timing time, TDD UL timing time, first conversion point switching time SW1 and second conversion point switching time SW2 obtained from the query timing relationship correspondence table, and the frame synchronization indication control modulation module to perform OOK modulation on the carrier to generate an OOK signal;

[0132] (4) Send the carrier frequency and table index to the slave device through the communication module;

[0133] (5) Store the timing correspondence table. If the timing correspondence table changes, the new timing correspondence table is sent to the slave through the communication module so that the timing correspondence table between the master and the slave remains consistent.

[0134] See Figure 4 :

[0135] The slave device should perform the following functions:

[0136] (1) Select the filter channel of the frequency selection module according to the carrier frequency point broadcast by the host;

[0137] (2) The demodulation host sends an OOK signal to obtain the TDD DL timing and periodically samples the TDD DL timing to obtain the demodulated TDD DL timing time;

[0138] (3) Query the time series correspondence table based on the host broadcast table index i to obtain the TDD DL time series;

[0139] (4) Compare the demodulated TDD DL timing with the table lookup time and check if the difference between the two meets the tolerance requirements; if it does, generate the TDD uplink / downlink switching timing according to the timing correspondence table; if it does not meet the requirements, report a timing regeneration failure message to the host.

[0140] The slave unit includes a slave antenna, a slave combiner, a frequency selection module, a level control module, a demodulation module, a timing regeneration module, a slave communication module, and a slave control module.

[0141] The slave antenna is used to receive and transmit OOK signals and communication signals, and is connected to the slave combiner;

[0142] The slave combiner is used to combine / separate OOK signals and communication signals, and is connected to the frequency selection module and the slave communication module;

[0143] The frequency selection module is used to filter the OOK signal and is connected to the level control module and the slave control module.

[0144] See Figure 5 :

[0145] The frequency selection module includes a first single-pole triple-throw switch, an F1 bandpass filter, an F2 bandpass filter, an F3 bandpass filter, and a second single-pole triple-throw switch.

[0146] The frequency selection module can filter three carrier frequencies, which can be switched via a switch.

[0147] The level control module is used to control the power of the OOK signal, so that the power entering the demodulation module is a preset constant value, and is connected to the demodulation module;

[0148] See Figure 6 :

[0149] The level control module includes an adjustable attenuator and a PA (Power Amplifier).

[0150] The adjustable attenuator is controlled by a control module to attenuate the signal power on the link and is connected to the PA.

[0151] PA amplifies the signal on the link and connects to the next stage of the link.

[0152] The demodulation module is used to demodulate the TDD DL timing from the OOK signal and is connected to the timing regeneration module;

[0153] The timing regeneration module is used to periodically sample the TDD DL timing to obtain the TDD DL timing time, and calculate the difference between the TDD DL timing time obtained by looking up the table according to table index i. The module then performs a tolerance judgment on the difference. If the tolerance requirement is met, the module generates the TDD uplink / downlink switching timing according to the timing correspondence table. If the tolerance requirement is not met, the module informs the slave control module. The timing regeneration module is connected to the slave control module.

[0154] The slave communication module is used to communicate with the master and is connected to the slave control module;

[0155] The slave control module performs the following functions:

[0156] (1) Switch the frequency selection module to the corresponding filtering channel according to the carrier frequency point broadcast by the host;

[0157] (2) The power entering the demodulation module is kept constant according to the power control level of the OOK signal;

[0158] (3) The timing regeneration failure message is reported to the host through the slave communication module;

[0159] (4) Send the host broadcast table index i to the timing regeneration module;

[0160] (5) Store the timing mapping table and synchronize the table to the timing regeneration module.

[0161] This invention can be used not only in a master-slave mode, but also in a master-multiple-slave mode.

[0162] See Figure 7 :

[0163] The embodiment provides a one-master-four-slave time synchronization system. When the master receives timing regeneration failure messages reported by multiple slaves, the carrier frequency can be switched using the majority principle. That is, the master will only switch the carrier frequency when there are ≥2 slaves reporting timing regeneration failure messages.

[0164] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A method for time synchronization between a master and a slave, characterized by, The method comprises the following steps: S1: obtaining TDD uplink-downlink time slot ratio and special sub-frame format information, and generating frame synchronization indication; obtaining table index i, TDD DL timing time, TDD UL timing time, first switching point switching time SW1 and second switching point switching time SW2 by querying timing relationship corresponding table; S2: generating TDD uplink-downlink switching timing of the host according to the obtained TDD DL timing time, TDD UL timing time, first switching point switching time SW1, second switching point switching time SW2 and frame synchronization indication; S3: generating carrier frequency point, and generating OOK signal by OOK modulation on the carrier frequency point; S4: sending the amplified and filtered OOK signal to the slave, and sending the carrier frequency point and the table index i to the slave; S5: switching the slave to the filtered channel corresponding to the carrier frequency point; S6: demodulating the TDD DL timing from the sent OOK signal, periodically sampling the demodulated TDD DL timing, obtaining demodulated TDD DL timing time Ts, and obtaining TDD DL timing time Te corresponding to the table index i by querying the timing relationship corresponding table according to the sent table index i; S7: calculating the difference Δ of Ts and Te, judging whether |Δ|≤δ, δ is the allowable range, δ is a positive value, if yes, proceeding to S8, if no, sending timing regeneration failure message to the host, and then entering S3; S8: obtaining TDD DL timing time, TDD UL timing time, first switching point switching time SW1, second switching point switching time SW2 and frame header offset by querying the timing relationship corresponding table through the table index i, and generating TDD uplink-downlink switching timing of the slave; Wherein the frame header offset is X, X is non-zero; if X is positive, the slave moves the entire TDD uplink-downlink timing forward by Xns after receiving the rising edge of the OOK signal; if X is negative, the slave moves the entire TDD uplink-downlink timing backward by Xns after receiving the rising edge of the OOK signal.

2. The method for time synchronization of master and slave according to claim 1, characterized in that, The timing relationship corresponding table comprises table index i, i is a positive integer, uplink-downlink time slot ratio, special sub-frame format, frame header offset, TDD DL timing time, first switching point switching time SW1, TDD UL timing time and second switching point switching time SW2.

3. The method for time synchronization of master and slave machines according to claim 1, wherein, The table index i is unique and is a positive integer, and each table index i corresponds to different uplink-downlink time slot ratio, special sub-frame format, frame header offset, TDD DL timing time, first switching point switching time SW1, TDD UL timing time and second switching point switching time SW2.

4. The method for time synchronization between master and slave according to claim 1, wherein, The timing relationship corresponding table saved by the host and the slave is a synchronization table, when the timing relationship corresponding table changes, the host needs to send the changed timing relationship corresponding table to the slave, so that the host and the slave remain consistent.

5. The method for time synchronization of master and slave according to claim 1, characterized in that, When the host receives multiple timing regeneration failure messages reported by the slaves, the carrier frequency point can be switched by majority principle, that is, when the number of slaves reporting timing regeneration failure message is greater than or equal to 2, the host switches the carrier frequency point.

6. An apparatus for time synchronization between a master and a slave, the apparatus comprising: The master includes a source synchronization module, a frequency generation module, an OOK modulation module, a transmitting module, a master control module, a master communication module, a master combiner and a master antenna. The source synchronization module is used for obtaining TDD uplink and downlink time slot ratio and special sub-frame format information, and simultaneously outputting frame synchronization indication to the control module. The master control module is used for generating TDD uplink and downlink switching time sequence of the master, and is used for controlling the frequency generation module to generate a carrier frequency point and sending the carrier frequency point to the OOK modulation module. The master control module is used for controlling the OOK modulation module to perform OOK modulation on the carrier frequency point to generate an OOK signal, and sending the OOK signal to the transmitting module. The transmitting module is used for amplifying and filtering the OOK signal and sending the OOK signal to the master combiner. The master combiner is used for combining the OOK signal and a communication signal and sending the combined signal to the master antenna. The master antenna is used for sending the received OOK signal and communication signal to the slave. The control module sends the table index i, the carrier frequency point and the time sequence relationship corresponding table to the communication module, and the communication module is used for interacting the table index i, the carrier frequency point and the time sequence relationship corresponding table between the master and the slave. The slave includes a slave antenna, a slave combiner, a frequency selection module, a level control module, a demodulation module, a time sequence regeneration module, a slave communication module and a slave control module. The slave antenna is used for receiving the OOK signal and the communication signal and sending the received signal to the slave combiner. The slave combiner is used for separating the OOK signal and the communication signal, and sending the OOK signal to the frequency selection module. The slave communication module is used for receiving the table index i, the carrier frequency point and the time sequence relationship corresponding table sent by the master and sending the received table to the slave control module. The slave control module controls the frequency selection module to switch to a filter channel corresponding to the carrier frequency point according to the carrier frequency point sent by the master, and filters the OOK signal. The slave control module controls the level control module to control the power of the OOK signal. The demodulation module is used for demodulating the TDD DL time sequence from the OOK signal, and sending the demodulated time sequence to the time sequence regeneration module. The time sequence regeneration module is used for judging whether the TDD DL time sequence is within a tolerance range, and performing subsequent processing on the judgment result.

7. The device for time synchronization between master and slave according to claim 6, wherein, The level control module includes an adjustable attenuator and a PA, and the adjustable attenuator is connected to the PA. The adjustable attenuator is controlled by the control module to attenuate the signal power on the link. The PA is used for amplifying the signal on the link.

8. The device for time synchronization of master and slave machines according to claim 6, wherein The frequency selection module includes a first single-pole multi-throw switch, a second single-pole multi-throw switch and a plurality of band-pass filters, the plurality of band-pass filters are arranged side by side, and the two ends of each band-pass filter are respectively connected to the switch contacts of the first single-pole multi-throw switch and the second single-pole multi-throw switch. The first single-pole multi-throw switch and the second single-pole multi-throw switch are used for controlling the switches to switch to the corresponding channels according to the carrier frequency point sent by the master.

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