WO2023087738A1 - Air interface synchronization method and system for indoor distribution base station - Google Patents

Abstract

Provided in the present application are an air interface synchronization method and system for an indoor distribution base station. The method comprises: acquiring synchronization information sent by a synchronization source base station, determining a downlink timing reference, and intercepting wireless frame data; acquiring a signal-to-noise ratio of an initial synchronization stage on the basis of the wireless frame data, and obtaining a signal-to-noise ratio threshold on the basis of the signal-to-noise ratio of the initial synchronization stage; acquiring a downlink air interface signal on the basis of a preset period, acquiring, from the downlink air interface signal, a real-time synchronization state and a frame header relative offset value of the synchronization source base station, and acquiring a signal-to-noise ratio of a synchronization maintenance stage; determining a timing reference adjustment policy on the basis of the real-time synchronization state and the result of comparison between the signal-to-noise ratio of the synchronization maintenance stage and the signal-to-noise ratio threshold; and if it is determined that the real-time synchronization state shows out of sync and synchronization is not recovered within a preset number of instances of period detection, performing adaptive pre-compensation. By means of the present application, insofar as the hardware costs of a base station are not increased and the implementation complexity is low, the stability of an air interface synchronization state of an indoor distribution base station in a complex environment is effectively improved, and the range of application scenarios of the indoor distribution base station is expanded.

Description

Air interface synchronization method and system for indoor base station

Cross References to Related Applications

This application claims the priority of the Chinese patent application filed on November 16, 2021 with the application number 202111357005.6 and the title of the invention is "A Method and System for Air Interface Synchronization of Indoor Base Station", which is incorporated herein by reference in its entirety.

technical field

The present application relates to the technical field of wireless communication, and in particular to an air interface synchronization method and system of an indoor base station.

Background technique

With the rapid development of mobile communications and the improvement of mobile terminals and network conditions, mobile services have gradually transitioned from simple voice services and text services in the early days to multimedia services with richer applications, and the application scenarios have also expanded from a wide range of outdoor scenarios to Indoor coverage of hotspot scenes.

The mobile communication system has high requirements on synchronization technology, among which uplink and downlink time slot alignment, high-quality and reliable data transmission, and handover between cells all need to rely on precise synchronization technology to achieve. Especially in the time division duplex communication system, all cells are required to be strictly synchronized, including time slot synchronization, system frame synchronization and subframe synchronization, so as to avoid mutual interference between base stations and terminals. Global Positioning System (GPS), IEEE1588v2, and air interface synchronization are the current mainstream synchronization methods between base stations. The mobile communication system uses GPS for synchronization to obtain high synchronization accuracy, but the indoor signal of GPS is poor and the failure rate is high. IEEE1588v2 synchronization technology is to set a clock server on a certain node in the transmission network, use the clock server as a synchronization source, inject synchronization timing information into the transmission network, and transmit the synchronization timing information to the base station as the base station synchronization reference, but this synchronization The technology needs to receive and send packets with the same delay, so the application conditions are strict and the cost is high. Air interface synchronization is to align the time by detecting the synchronization signal of the base station in the neighboring cell, and correct the frequency deviation by detecting the reference signal, so as to realize the mutual synchronization of the base stations in the network. For indoor coverage scenarios of miniaturized or miniaturized base stations, the conditions for using GPS synchronization and IEEE1588v2 synchronization are usually not met during equipment installation, so air interface synchronization is an effective solution to the synchronization problem in this scenario.

The air interface synchronization process is specifically divided into initial synchronization and synchronization maintenance. Synchronization maintenance is to continue to periodically detect the synchronization signal or reference signal sent by the synchronization source base station on the basis of obtaining the synchronization information of the synchronization source base station during the initial synchronization, so as to maintain the synchronization state between the base stations. The synchronization signal is divided into PSS (Primary Synchronization Signal, primary synchronization signal) and (Secondary Synchronization Signal, secondary synchronization signal), and the reference signal generally refers to CRS (Cell Reference Signal, cell reference signal). 3GPP proposed two indoor air interface synchronization technologies, one is to transmit clock synchronization signals based on special subframe guard interval (GP, Guard Period), and the other is to detect reference signals of synchronization source cells based on silent subframes to obtain time synchronization. Usually mobile operators will adjust the macro base station parameters to optimize the access network according to the changes in the wireless network environment, or configure certain idle periods based on energy saving factors to reduce the downlink transmission power of the macro base station, or a certain frequency band may appear strong due to changes in the indoor environment. The interference signal will directly affect the quality of the downlink signal received by the indoor small or micro base station, which will cause the downlink synchronization of the air interface of the indoor base station to be out of sync. Especially in time-division duplex systems, the long-term downlink out-of-synchronization caused by the loss of the synchronization source will cause the accumulated offset between the frame header of the indoor base station and the frame header of the macro base station to increase. When it exceeds a certain range, the downlink signal of the macro base station will partially overlap with the uplink time slot of the indoor base station in time, thus seriously affecting the access of the mobile terminal.

Therefore, it is an urgent problem for those skilled in the art to provide a method for improving the stability of the air interface synchronization state in a low signal-to-noise ratio environment without increasing the hardware cost of the base station and implementing a low-complexity method.

Contents of the invention

This application provides a method and system for air interface synchronization of indoor base stations, which are used to solve the problem of out-of-synchronization of the air interface due to the deterioration of the downlink signal-to-noise ratio of the synchronization frequency point when small and medium-sized or micro base stations in the prior art adopt the air interface synchronization method in the indoor division scene. Defects that are difficult to self-recover.

In a first aspect, the present application provides an air interface synchronization method of an indoor base station, including:

Obtaining synchronization information sent by the synchronization source base station, determining a downlink timing reference based on the synchronization information, and intercepting wireless frame data;

Obtaining an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and obtaining a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;

Obtain a downlink air interface signal according to a preset period, acquire a real-time synchronization state and a frame header relative offset value of a synchronization source base station from the downlink air interface signal, and acquire a synchronization maintenance stage signal-to-noise ratio based on the frame header relative offset value;

Determine a timing reference adjustment strategy based on the real-time synchronization state and the comparison result between the signal-to-noise ratio in the synchronization maintenance phase and the signal-to-noise ratio threshold;

If it is judged that the real-time synchronization status is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed.

According to a method for air interface synchronization of indoor base stations provided in this application, the synchronization information sent by the synchronization source base station is obtained, the downlink timing reference is determined based on the synchronization information, and wireless frame data is intercepted, including:

Determine the air interface timing of the air interface data stream and the position of the synchronization signal in the wireless frame based on the synchronization information, calculate and obtain the starting position of the frame header of the synchronization source base station, and use the starting position of the frame header of the synchronization source base station as the downlink timing reference ;

Based on the downlink timing reference, several wireless frame data are intercepted from the air interface data flow.

According to an air interface synchronization method of an indoor base station provided in the present application, the signal-to-noise ratio in the initial synchronization stage is obtained based on the wireless frame data, and the signal-to-noise ratio threshold is obtained according to the signal-to-noise ratio in the initial synchronization stage, including:

performing time-frequency conversion on the wireless frame data to obtain a corresponding downlink reference signal;

Calculate resource block RB data occupied by the downlink reference signal based on discrete Fourier transform DFT channel estimation to obtain noise energy RIP;

A number of initial SNR statistics are obtained from the RIP, and the number of initial SNR statistics are accumulated and averaged to obtain the SNR threshold.

According to an air interface synchronization method of an indoor base station provided in the present application, based on the real-time synchronization state and the comparison result of the signal-to-noise ratio in the synchronization maintenance stage and the signal-to-noise ratio threshold, a timing reference adjustment strategy is determined, including:

If the real-time synchronization state is synchronous and the signal-to-noise ratio in the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, the frame header relative offset value is inverted to obtain a first non-zero adjustment value, and the second A non-zero adjustment value is used as an adjustment step to adjust the current timing reference position, and the first non-zero adjustment value is stored in a cyclic array with a preset length;

If the real-time synchronization state is synchronous and the signal-to-noise ratio in the synchronization maintenance stage is less than the signal-to-noise ratio threshold, then accumulate the relative offset value of the frame header to obtain an accumulated value, and when the accumulated value reaches the adjustment threshold , inverting the accumulated value to obtain a second non-zero adjustment value, using the second non-zero adjustment value as an adjustment step to adjust the current timing reference position, and saving the second non-zero adjustment value to a preset a circular array of length, and zeroing out said accumulated value;

If the real-time synchronization state is out of synchronization and the signal-to-noise ratio in the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, the relative offset value of the frame header is accumulated, and the current timing reference position is not adjusted;

If the real-time synchronization state is out of synchronization and the signal-to-noise ratio in the synchronization maintaining stage is smaller than the signal-to-noise ratio threshold, no processing is performed.

According to an air interface synchronization method of an indoor base station provided by the present application, if it is judged that the real-time synchronization state is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed, including:

Accumulate several adjustment values in the cyclic array to obtain a first accumulation value, take the number of adjustment values as the first pre-compensation cycle, and adjust the current timing reference based on the first accumulation value and the first pre-compensation cycle position, after the first pre-compensation cycle ends, determine the current synchronization state;

If the first accumulated value is 0, the last adjusted value in the several adjusted values is removed, and the remaining adjusted value is accumulated to obtain the second accumulated value, and the number of adjusted values minus 1 is the second pre-compensation cycle , adjusting the current timing reference position based on the second accumulated value and the second pre-compensation cycle, and determining the current synchronization state after the second pre-compensation cycle ends;

By analogy, if the real-time synchronization state is out of sync in the current pre-compensation cycle, enter the next pre-compensation cycle to continue pre-compensation.

According to an air interface synchronization method of an indoor base station provided in this application, it also includes:

If the real-time synchronization states are all synchronous within a preset number of consecutive detection periods after the end of the current precompensation period, the adaptive precompensation is turned off, and the timing reference adjustment mechanism is restored.

In the second aspect, the present application also provides an air interface synchronization system for indoor base stations, including:

A first processing module, configured to acquire synchronization information sent by a synchronization source base station, determine a downlink timing reference based on the synchronization information, and intercept wireless frame data;

The second processing module is used to obtain the signal-to-noise ratio in the initial synchronization stage based on the wireless frame data, and obtain the signal-to-noise ratio threshold according to the signal-to-noise ratio in the initial synchronization stage;

The third processing module is configured to acquire a downlink air interface signal according to a preset period, acquire a real-time synchronization status and a frame header relative offset value of a synchronization source base station from the downlink air interface signal, and acquire synchronization maintenance based on the frame header relative offset value stage signal-to-noise ratio;

An adjustment module, configured to determine a timing reference adjustment strategy based on the real-time synchronization state and the comparison result between the SNR in the synchronization maintenance phase and the SNR threshold;

The pre-compensation module is configured to perform adaptive pre-compensation if it is judged that the real-time synchronization status is out of synchronization and synchronization is not restored within the preset number of detection cycles.

In a third aspect, the present application also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and operable on the processor. The steps of the air interface synchronization method of indoor base stations are described.

In the fourth aspect, the present application also provides a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the air interface synchronization method for indoor base stations as described in any one of the above are implemented. .

In a fifth aspect, the present application further provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the air interface synchronization method for an indoor base station as described above are implemented.

The air interface synchronization method and system of indoor base stations provided by this application, through periodic detection of downlink signals of synchronization source base stations, periodic statistics of detection results and estimation of frame header offsets, in low signal-to-noise ratio environments after the synchronization state is lost, the indoor division The timing reference of the base station is adjusted by self-adaptive pre-compensation, so as to maintain the synchronization state of the air interface, without the need for auxiliary synchronization equipment such as GPS, and without frequent switching of synchronization frequency points and frequent switching of RF channels, so as not to increase the hardware cost of the base station and realize the complexity Under the premise of low cost, it can effectively improve the stability of the air interface synchronization state of indoor base stations in complex environments, and expand the scope of application scenarios of indoor base stations.

Description of drawings

In order to more clearly illustrate the technical solutions in this application or the prior art, the accompanying drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are the present For some embodiments of the application, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic flow chart of the air interface synchronization method of the indoor base station provided by the present application;

FIG. 2 is a schematic flow diagram of a timing reference adjustment strategy provided by the present application;

Fig. 3 is a schematic flow chart of the adaptive pre-compensation provided by the present application;

FIG. 4 is a schematic structural diagram of the air interface synchronization system of the indoor base station provided by the present application;

FIG. 5 is a schematic structural diagram of an electronic device provided by the present application.

Detailed ways

In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in this application. Obviously, the described embodiments are part of the embodiments of this application , but not all examples. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Aiming at the problems existing in the prior art, this application proposes an air interface synchronization maintenance method for indoor small or micro base stations in a low SNR environment to solve the loss of synchronization state of the original air interface synchronization scheme in a low SNR environment A problem that is difficult to self-recover after.

Fig. 1 is a schematic flow chart of the air interface synchronization method of indoor base stations provided by the present application, as shown in Fig. 1 , including:

Step S1, obtaining synchronization information sent by the synchronization source base station, determining a downlink timing reference based on the synchronization information, and intercepting wireless frame data;

In the initial synchronization stage, after obtaining the synchronization information of the synchronization source base station, the indoor base station sets its downlink timing reference through the internal clock control unit, and intercepts the wireless frame data at the same time.

Step S2, obtaining the signal-to-noise ratio in the initial synchronization stage based on the wireless frame data, and obtaining the signal-to-noise ratio threshold according to the signal-to-noise ratio in the initial synchronization stage;

The intercepted wireless frame data is obtained through the channel estimation unit to obtain the signal-to-noise ratio in the initial synchronization stage, and the calculation results are accumulated and averaged to obtain the signal-to-noise ratio threshold.

Step S3: Obtain the downlink air interface signal according to the preset period, obtain the real-time synchronization status and the relative offset value of the frame header of the synchronization source base station from the downlink air interface signal, and obtain the signal-to-noise ratio in the synchronization maintenance stage based on the relative offset value of the frame header ;

After entering the synchronization maintenance phase, the indoor base station periodically detects the downlink air interface signal through the air interface monitoring unit, obtains the real-time synchronization status and the relative offset value with the frame header of the synchronization source base station, and obtains the synchronization maintenance phase through the channel estimation unit SNR.

Step S4, determining a timing reference adjustment strategy based on the real-time synchronization state and the comparison result of the SNR in the synchronization maintenance phase and the SNR threshold;

The indoor base station selects the timing reference adjustment strategy according to the real-time synchronization status and the result of comparing the real-time SNR with the SNR threshold.

Step S5, if it is judged that the real-time synchronization status is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed.

If the real-time synchronization state is out of synchronization and the synchronization has not been restored for several detection cycles, the indoor base station performs adaptive pre-compensation for the timing reference offset.

This application periodically detects the downlink signal of the synchronization source base station, periodically counts the detection results and estimates the frame header offset, and performs adaptive pre-compensation adjustment on the timing reference of the indoor base station after the synchronization state is lost in a low signal-to-noise ratio environment, thereby To maintain the air interface synchronization state, there is no need to rely on auxiliary synchronization equipment such as GPS, and it is not necessary to frequently switch the synchronization frequency point and frequently switch the RF channel, so that the indoor base station can be effectively improved without increasing the hardware cost of the base station and with low implementation complexity. The stability of the air interface synchronization state in complex environments expands the scope of application scenarios for indoor base stations.

Based on the foregoing embodiments, step S1 includes:

Determine the air interface timing of the air interface data stream and the position of the synchronization signal in the wireless frame based on the synchronization information, calculate and obtain the starting position of the frame header of the synchronization source base station, and use the starting position of the frame header of the synchronization source base station as the downlink timing reference ;

Based on the downlink timing reference, several wireless frame data are intercepted from the air interface data flow.

Specifically, the downlink timing reference MFC _init proposed in the initial synchronization stage of this application is based on the initial synchronization information of the synchronization source base station by the clock control unit inside the indoor base station, that is, the timing of the air interface and the position of the synchronization signal in the radio frame, according to 3GPP The protocol calculates the starting position of the frame header of the synchronization source base station, and sets it as the time reference of the indoor base station.

Then intercept the wireless frame data, and intercept N complete wireless frame data lengths from the air interface data stream received in the initial synchronization phase according to the successful result of the initial synchronization, where N>=1.

This application determines the downlink timing reference in the initial synchronization stage, and intercepts the wireless frame data as a reference for adjusting the subsequent real-time synchronization state, which has the characteristics of easy acquisition and no need to rely on hardware.

Based on any of the above-mentioned embodiments, step S2 includes:

performing time-frequency conversion on the wireless frame data to obtain a corresponding downlink reference signal;

Calculate resource block RB data occupied by the downlink reference signal based on discrete Fourier transform DFT channel estimation to obtain noise energy RIP;

A number of initial SNR statistics are obtained from the RIP, and the number of initial SNR statistics are accumulated and averaged to obtain the SNR threshold.

Specifically, when further calculating the signal-to-noise ratio in the initial synchronization stage, firstly perform time-frequency conversion processing on the intercepted N complete wireless frames, and then take out the corresponding downlink reference signal, input it to the channel estimation unit, and calculate The noise energy (RIP), and then obtain the signal-to-noise ratio (SNR), and the calculation method of the signal-to-noise ratio threshold is to calculate the average by accumulating the N initial signal-to-noise ratio statistics obtained above.

Taking the TD-LTE base station as an example, first segment the intercepted N wireless frame data according to the length of the system wireless frame, and divide the data of subframe 1 or subframe 9 in each 10ms wireless frame in units of time domain symbols Perform decyclic prefix and FFT calculation processing respectively, and then take out the resource block (RB) data occupied by the downlink reference signal, input it to the channel estimation unit, obtain the noise energy (RIP) through DFT channel estimation, and then obtain the signal-to-noise ratio ( SNR), and finally the SNR threshold δ is obtained by accumulating the N initial SNR statistics obtained above and averaging them.

Here, the detection period of the air interface listening unit may be set to 2 ⁿ times 10 ms, where n>=0 and n<=5, and n is an integer.

This application calculates the signal-to-noise ratio and signal-to-noise ratio threshold in the initial synchronization stage as the basis for judging whether the system needs to perform real-time synchronization. It has the characteristics of simple calculation and convenient implementation, and does not require additional hardware resources as support.

Based on any of the above-mentioned embodiments, step S3 includes:

If the real-time synchronization state is synchronous and the signal-to-noise ratio in the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, the frame header relative offset value is inverted to obtain a first non-zero adjustment value, and the second A non-zero adjustment value is used as an adjustment step to adjust the current timing reference position, and the first non-zero adjustment value is stored in a cyclic array with a preset length;

If the real-time synchronization state is synchronous and the signal-to-noise ratio in the synchronization maintenance stage is less than the signal-to-noise ratio threshold, then accumulate the relative offset value of the frame header to obtain an accumulated value, and when the accumulated value reaches the adjustment threshold , inverting the accumulated value to obtain a second non-zero adjustment value, using the second non-zero adjustment value as an adjustment step to adjust the current timing reference position, and saving the second non-zero adjustment value to a preset a circular array of length, and zeroing out said accumulated value;

If the real-time synchronization state is out-of-synchronization and the signal-to-noise ratio in the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, the relative offset value of the frame header is accumulated, and the current timing reference position is not adjusted;

If the real-time synchronization state is out of synchronization and the signal-to-noise ratio in the synchronization maintaining stage is smaller than the signal-to-noise ratio threshold, no processing is performed.

Specifically, as shown in Figure 2, the timing reference adjustment strategy involved in this application specifically includes:

(1) When the real-time state is synchronous and the SNR is higher than or equal to the signal-to-noise ratio threshold δ, the confidence of the air interface synchronization result is the highest, and the internal clock control unit inverts the periodically detected frame header relative offset value MFC _offset as a step Long-term real-time adjustment of the current timing reference position, and save the non-zero adjustment value (-MFC _offset ) to the loop array a of length L;

(2) When the real-time state is synchronous and the SNR is lower than the signal-to-noise ratio threshold δ, the internal clock control unit accumulates the periodically detected frame header relative offset value MFC _offset , and when the absolute value of the accumulated value reaches the adjustment threshold β Afterwards, the internal clock control unit reverses the accumulated value MFC _sum as a step to adjust the current timing reference position, and saves the adjusted value (-MFC _sum ) to the loop array a, and resets the accumulated value to zero;

(3) When the real-time state is out of synchronization and the SNR is higher than or equal to the signal-to-noise ratio threshold, only the relative offset value of the frame header is accumulated, and the timing reference position is not adjusted;

(4) When the real-time state is out of synchronization and the SNR is lower than the signal-to-noise ratio threshold δ, the confidence of the air interface synchronization result is the lowest, and no processing is performed at this time.

Here, the loop array a defaults to save the latest L adjustment values. Before each data write, add 1 to the serial number of all elements in the loop array a and move the element content backward, that is, a(L-1)=a(L- 2), a(L-2)=a(L-3)...a(2)=a(1), a(1)=a(0), the original L-th element is covered, and finally the current The data is saved to the first position a(0) of the array.

The adjustment threshold β is set to T minimum time units, and the minimum time unit is related to the system sampling rate. Taking the 20M bandwidth LTE system as an example, its 30.72M sampling rate corresponds to β=T×(1/30720000)s.

This application comprehensively predicts the real-time status of the system and the comparison results of the SNR and signal-to-noise ratio threshold, obtains and executes the timing reference adjustment strategy, and also saves multiple adjustment values by setting a cyclic array, which can flexibly perform dynamic adjustments based on the real-time status of the system. compensate.

Based on any of the above-mentioned embodiments, step S5 includes:

Accumulate several adjustment values in the cyclic array to obtain a first accumulation value, take the number of adjustment values as the first pre-compensation cycle, and adjust the current timing reference based on the first accumulation value and the first pre-compensation cycle position, after the first pre-compensation cycle ends, determine the current synchronization state;

If the first accumulated value is 0, the last adjusted value in the several adjusted values is removed, and the remaining adjusted value is accumulated to obtain the second accumulated value, and the number of adjusted values minus 1 is the second pre-compensation cycle , adjusting the current timing reference position based on the second accumulated value and the second pre-compensation cycle, and determining the current synchronization state after the second pre-compensation cycle ends;

By analogy, if the real-time synchronization state is out of sync in the current pre-compensation cycle, enter the next pre-compensation cycle to continue pre-compensation.

Specifically, as shown in Figure 3, the adaptive pre-compensation proposed in this application specifically includes:

Accumulate and sum the L adjustment values stored in the current loop array to obtain the accumulated value Sum0. The indoor base station adjusts the current timing reference position with L as the period and Sum0 as the step size. After the current pre-compensation period ends, the current synchronization state is detected. Choose to continue the pre-compensation process or exit the pre-compensation process according to the result.

Furthermore, if Sum0 is 0, continue to calculate Sum1=∑{a(0),a(1),...,a(L-2)}, change the pre-compensation adjustment step to Sum1, and change the pre-compensation period for L-1.

This application adopts an adaptive pre-compensation processing flow to dynamically adjust the adjustment value in the cyclic array according to whether the current state of the system meets the synchronization requirement, so as to realize real-time synchronization compensation for system offset.

Based on any of the above embodiments, it also includes:

If the real-time synchronization states are all synchronous within a preset number of consecutive detection periods after the end of the current precompensation period, the adaptive precompensation is turned off, and the timing reference adjustment mechanism is restored.

It should be noted that after the end of the current pre-compensation cycle, this application continues to continuously detect X cycles. If the real-time synchronization status is synchronized, the adaptive pre-compensation is turned off, and the indoor base station resumes the timing reference adjustment mechanism to continue to maintain the air interface. sync status. Here, X is a positive integer greater than 0. In this application, it is set that X>=3 and X<L, so as to ensure a certain number of detection cycles but not infinite.

This application continues to supplement periodic detection after adaptive pre-compensation to ensure that after the system enters a stable synchronization state, the adaptive pre-compensation process is closed to effectively save system resources.

The following describes the air interface synchronization system of indoor base stations provided by this application. The air interface synchronization system of indoor base stations described below and the air interface synchronization method of indoor base stations described above can be referred to in correspondence.

Fig. 4 is a schematic structural diagram of the indoor base station air interface synchronization system provided by the present application, as shown in Fig. 4, including: a first processing module 41, a second processing module 42, a third processing module 43, an adjustment module 44 and a pre-compensation module 45, of which:

The first processing module 41 is used to obtain the synchronization information sent by the synchronization source base station, determine the downlink timing reference based on the synchronization information, and intercept the wireless frame data; the second processing module 42 is used to obtain the initial synchronization stage information based on the wireless frame data Noise ratio, the signal-to-noise ratio threshold is obtained according to the signal-to-noise ratio in the initial synchronization stage; the third processing module 43 is used to obtain the downlink air interface signal according to the preset cycle, and obtain the real-time synchronization status and the frame of the synchronization source base station from the downlink air interface signal Head relative offset value, based on the frame header relative offset value to obtain the SNR in the synchronization maintenance stage; the adjustment module 44 is used to obtain the SNR threshold based on the real-time synchronization state, the SNR in the synchronization maintenance stage, and the SNR threshold The comparison result determines the timing reference adjustment strategy; the pre-compensation module 45 is used to perform adaptive pre-compensation if it is judged that the real-time synchronization state is out of synchronization and synchronization is not restored within the preset number of detection cycles.

This application periodically detects the downlink signal of the synchronization source base station, periodically counts the detection results and estimates the frame header offset, and performs adaptive pre-compensation adjustment on the timing reference of the indoor base station after the synchronization state is lost in a low signal-to-noise ratio environment, thereby To maintain the air interface synchronization state, there is no need to rely on auxiliary synchronization equipment such as GPS, and it is not necessary to frequently switch the synchronization frequency point and frequently switch the RF channel, so that the indoor base station can be effectively improved without increasing the hardware cost of the base station and with low implementation complexity. The stability of the air interface synchronization state in complex environments expands the scope of application scenarios for indoor base stations.

FIG. 5 illustrates a schematic diagram of the physical structure of an electronic device. As shown in FIG. 5, the electronic device may include: a processor (processor) 510, a communication interface (Communications Interface) 520, a memory (memory) 530 and a communication bus 540, Wherein, the processor 510 , the communication interface 520 , and the memory 530 communicate with each other through the communication bus 540 . The processor 510 can call the logic instructions in the memory 530 to execute the air interface synchronization method of the indoor base station. The method includes: obtaining the synchronization information sent by the synchronization source base station, determining the downlink timing reference based on the synchronization information, and intercepting the wireless frame data; Acquire the signal-to-noise ratio in the initial synchronization stage based on the wireless frame data, obtain the signal-to-noise ratio threshold according to the signal-to-noise ratio in the initial synchronization stage; obtain a downlink air interface signal according to a preset period, and obtain real-time synchronization status and synchronization from the downlink air interface signal The relative offset value of the frame header of the source base station, based on the relative offset value of the frame header, the signal-to-noise ratio of the synchronization maintenance stage is obtained; based on the real-time synchronization state and the signal-to-noise ratio of the synchronization maintenance stage and the signal-to-noise ratio threshold Based on the comparison results, a timing reference adjustment strategy is determined; if it is judged that the real-time synchronization state is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed.

In addition, the above logic instructions in the memory 530 may be implemented in the form of software function units and be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disc, etc., which can store program codes. .

On the other hand, the present application also provides a computer program product, the computer program product includes a computer program, the computer program can be stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, the computer can Execute the air interface synchronization method of the indoor base station provided by the above methods, the method includes: obtaining synchronization information sent by the synchronization source base station, determining a downlink timing reference based on the synchronization information, and intercepting wireless frame data; obtaining based on the wireless frame data The signal-to-noise ratio in the initial synchronization stage, the signal-to-noise ratio threshold is obtained according to the signal-to-noise ratio in the initial synchronization stage; the downlink air interface signal is obtained according to the preset cycle, and the real-time synchronization status and the relative deviation of the frame header of the synchronization source base station are obtained from the downlink air interface signal Shift value, based on the relative offset value of the frame header to obtain the signal-to-noise ratio in the synchronization maintenance stage; based on the real-time synchronization state and the comparison result between the synchronization maintenance stage signal-to-noise ratio and the signal-to-noise ratio threshold, determine the timing reference adjustment Strategy: if it is judged that the real-time synchronization status is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed.

In another aspect, the present application also provides a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it is implemented to perform the method for synchronizing the air interface of the indoor base station provided by the above-mentioned methods. The method includes: obtaining synchronization information sent by a synchronization source base station, determining a downlink timing reference based on the synchronization information, and intercepting wireless frame data; obtaining an initial synchronization phase signal-to-noise ratio based on the wireless frame data; Obtain the signal-to-noise ratio threshold; obtain the downlink air interface signal according to the preset period, obtain the real-time synchronization status and the relative offset value of the frame header of the synchronization source base station from the downlink air interface signal, and obtain the synchronization maintenance based on the relative offset value of the frame header stage signal-to-noise ratio; based on the real-time synchronization state and the comparison result of the synchronization maintenance stage signal-to-noise ratio and the signal-to-noise ratio threshold, determine a timing reference adjustment strategy; if it is judged that the real-time synchronization state is out of synchronization Assuming that synchronization is not restored within the number of detection cycles, adaptive pre-compensation is performed.

The device embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without any creative effort.

Through the above description of the implementations, those skilled in the art can clearly understand that each implementation can be implemented by means of software plus a necessary general-purpose hardware platform, and of course also by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in computer-readable storage media, such as ROM/RAM, magnetic discs, optical discs, etc., including several instructions to make a computer device (which may be a personal computer, server, or network device, etc.) execute the methods described in various embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims (10)

1. A method for air interface synchronization of indoor base stations, comprising:

   Obtaining synchronization information sent by the synchronization source base station, determining a downlink timing reference based on the synchronization information, and intercepting wireless frame data;

   Obtaining an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and obtaining a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;

   Obtain a downlink air interface signal according to a preset period, acquire a real-time synchronization state and a frame header relative offset value of a synchronization source base station from the downlink air interface signal, and acquire a synchronization maintenance stage signal-to-noise ratio based on the frame header relative offset value;

   Determine a timing reference adjustment strategy based on the real-time synchronization state and the comparison result between the signal-to-noise ratio in the synchronization maintenance phase and the signal-to-noise ratio threshold;

   If it is judged that the real-time synchronization status is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed.
2. The air interface synchronization method of indoor base stations according to claim 1, wherein the synchronization information sent by the synchronization source base station is obtained, the downlink timing reference is determined based on the synchronization information, and the wireless frame data is intercepted, including:

   Determine the air interface timing of the air interface data stream and the position of the synchronization signal in the wireless frame based on the synchronization information, calculate and obtain the starting position of the frame header of the synchronization source base station, and use the starting position of the frame header of the synchronization source base station as the downlink timing reference ;

   Based on the downlink timing reference, several wireless frame data are intercepted from the air interface data flow.
3. The air interface synchronization method of indoor base stations according to claim 1, wherein the signal-to-noise ratio of the initial synchronization stage is obtained based on the wireless frame data, and the signal-to-noise ratio threshold is obtained according to the signal-to-noise ratio of the initial synchronization stage, including:

   performing time-frequency conversion on the wireless frame data to obtain a corresponding downlink reference signal;

   Calculate resource block RB data occupied by the downlink reference signal based on discrete Fourier transform DFT channel estimation to obtain noise energy RIP;

   A number of initial SNR statistics are obtained from the RIP, and the number of initial SNR statistics are accumulated and averaged to obtain the SNR threshold.
4. The air interface synchronization method for indoor base stations according to claim 1, wherein based on the real-time synchronization state and the comparison result of the SNR in the synchronization maintenance phase and the SNR threshold, determining a timing reference adjustment strategy includes:

   If the real-time synchronization state is synchronous and the signal-to-noise ratio in the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, the frame header relative offset value is inverted to obtain a first non-zero adjustment value, and the second A non-zero adjustment value is used as an adjustment step to adjust the current timing reference position, and the first non-zero adjustment value is stored in a cyclic array with a preset length;

   If the real-time synchronization state is synchronous and the signal-to-noise ratio in the synchronization maintenance stage is less than the signal-to-noise ratio threshold, then accumulate the relative offset value of the frame header to obtain an accumulated value, and when the accumulated value reaches the adjustment threshold , inverting the accumulated value to obtain a second non-zero adjustment value, using the second non-zero adjustment value as an adjustment step to adjust the current timing reference position, and saving the second non-zero adjustment value to a preset a circular array of length, and zeroing out said accumulated value;

   If the real-time synchronization state is out of synchronization and the signal-to-noise ratio in the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, the relative offset value of the frame header is accumulated, and the current timing reference position is not adjusted;

   If the real-time synchronization state is out of synchronization and the signal-to-noise ratio in the synchronization maintaining stage is smaller than the signal-to-noise ratio threshold, no processing is performed.
5. The air interface synchronization method of indoor base stations according to claim 4, wherein if it is judged that the real-time synchronization state is out of synchronization and synchronization is not restored within the preset number of detection cycles, adaptive pre-compensation is performed, including:

   Accumulate several adjustment values in the cyclic array to obtain a first accumulation value, take the number of adjustment values as the first pre-compensation cycle, and adjust the current timing reference based on the first accumulation value and the first pre-compensation cycle position, after the first pre-compensation cycle ends, determine the current synchronization state;

   If the first accumulated value is 0, the last adjusted value in the several adjusted values is removed, and the remaining adjusted value is accumulated to obtain the second accumulated value, and the number of adjusted values minus 1 is the second pre-compensation cycle , adjusting the current timing reference position based on the second accumulated value and the second pre-compensation cycle, and determining the current synchronization state after the second pre-compensation cycle ends;

   By analogy, if the real-time synchronization state is out of sync in the current pre-compensation cycle, enter the next pre-compensation cycle to continue pre-compensation.
6. The air interface synchronization method of indoor base stations according to claim 1, further comprising:

   If the real-time synchronization states are all synchronous within a preset number of consecutive detection periods after the end of the current precompensation period, the adaptive precompensation is turned off, and the timing reference adjustment mechanism is restored.
7. An air interface synchronization system for indoor base stations, comprising:

   A first processing module, configured to acquire synchronization information sent by a synchronization source base station, determine a downlink timing reference based on the synchronization information, and intercept wireless frame data;

   The second processing module is used to obtain the signal-to-noise ratio in the initial synchronization stage based on the wireless frame data, and obtain the signal-to-noise ratio threshold according to the signal-to-noise ratio in the initial synchronization stage;

   The third processing module is configured to acquire a downlink air interface signal according to a preset period, acquire a real-time synchronization status and a frame header relative offset value of a synchronization source base station from the downlink air interface signal, and acquire synchronization maintenance based on the frame header relative offset value stage signal-to-noise ratio;

   An adjustment module, configured to determine a timing reference adjustment strategy based on the real-time synchronization state and the comparison result between the SNR in the synchronization maintenance phase and the SNR threshold;

   The pre-compensation module is configured to perform adaptive pre-compensation if it is judged that the real-time synchronization status is out of synchronization and synchronization is not restored within the preset number of detection cycles.
8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and operable on the processor, wherein the processor implements any one of claims 1 to 6 when executing the program Steps of the air interface synchronization method of indoor base stations.
9. A non-transitory computer-readable storage medium, on which a computer program is stored, wherein when the computer program is executed by a processor, the steps of the method for synchronizing the air interface of an indoor base station according to any one of claims 1 to 6 are implemented.
10. A computer program product, including a computer program, wherein when the computer program is executed by a processor, the steps of the air interface synchronization method for indoor base stations according to any one of claims 1 to 6 are implemented.

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