CN114126033A - Air interface synchronization method and system for indoor branch base station - Google Patents
Air interface synchronization method and system for indoor branch base station Download PDFInfo
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Abstract
The invention provides an air interface synchronization method and a system for an indoor division base station, wherein the method comprises the following steps: acquiring synchronization information sent by a synchronization source base station, determining a downlink timing reference, and intercepting wireless frame data; acquiring an initial synchronization stage signal-to-noise ratio based on wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio; acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage; determining a timing reference adjustment strategy based on a real-time synchronization state and a comparison result of a signal-to-noise ratio and a signal-to-noise ratio threshold in a synchronization maintenance stage; and if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times, performing self-adaptive pre-compensation. According to the invention, on the premise of not increasing the hardware cost of the base station and realizing low complexity, the stability of the air interface synchronization state of the indoor sub base station in a complex environment is effectively improved, and the application scene range of the indoor sub base station is expanded.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to an air interface synchronization method and system for an indoor division base station.
Background
With the rapid development of mobile communication and the increasing improvement of mobile terminals and network conditions, mobile services gradually transition from early pure voice services and text services to more abundantly applied multimedia services, and application scenes are also expanded from large-scale outdoor scenes to indoor coverage hotspot scenes.
Mobile communication systems have high requirements for synchronization techniques, in which uplink and downlink timeslot alignment, high-quality and reliable data transmission, and handover between cells need to be implemented by means of accurate synchronization techniques. In particular, in a tdd communication system, all cells are required to be strictly synchronized, including timeslot synchronization, system frame synchronization, and subframe synchronization, so as to avoid mutual interference between base stations and terminals. The Global Positioning System (GPS), IEEE1588v2, and air interface synchronization are currently mainstream inter-base station synchronization methods. The mobile communication system can obtain high synchronization accuracy by using GPS for synchronization, but the GPS has poor indoor signal and high failure rate. The IEEE1588v2 synchronization technology is to set a clock server at a certain node in a transmission network, inject synchronization timing information into the transmission network with the clock server as a synchronization source, and transmit the synchronization timing information to a base station as a base station synchronization reference, but the synchronization technology requires the same time delay for receiving and sending transmitted messages, and has strict application conditions and high cost. The air interface synchronization is to align time by detecting the synchronization signal of the neighboring base station, and to correct the frequency deviation by detecting the reference signal, thereby realizing the mutual synchronization of the base stations in the network. For an indoor coverage scenario of a miniaturized or miniaturized base station, conditions for using GPS synchronization and IEEE1588v2 synchronization are not usually met during equipment installation, so adopting air interface synchronization is a solution to effectively solve the synchronization problem in the scenario.
The air interface synchronization process is specifically divided into initial synchronization and synchronization maintenance. The synchronization maintenance is to continue to periodically detect the synchronization signal or the reference signal sent by the synchronization source base station to maintain the synchronization state between the base stations on the basis that the initial synchronization acquires the synchronization information of the synchronization source base station. Synchronization signals are classified into PSS (Primary Synchronization Signal) and Secondary Synchronization Signal (Secondary Synchronization Signal), and Reference signals are generally referred to as CRS (Cell Reference Signal). The 3GPP proposes two indoor air interface synchronization technologies, one is based on special subframe Guard interval (GP) transmission clock synchronization signal, and the other is based on silent subframe detection reference signal of the synchronization source cell to acquire time synchronization. Usually, a mobile operator adjusts parameters of a macro base station according to the environment change condition of a wireless network for optimizing an access network, or configures some idle periods based on energy-saving factors to reduce downlink transmission power of the macro base station, or a strong interference signal appears in a certain frequency band due to indoor environment change, and at this time, the quality of a downlink signal received by an indoor sub-miniature or micro base station is directly affected, so that air interface synchronization downlink desynchronization of the indoor sub-miniature or micro base station is caused. Especially in a time division duplex system, long-time downlink desynchronization caused by synchronous source loss can lead to larger and larger accumulated offset between the frame head of the indoor branch base station and the frame head of the macro base station, and when the offset of the frame head exceeds a certain range, a downlink signal of the macro base station can be partially overlapped with an uplink time slot of the indoor branch base station in time, so that the access of a mobile terminal is seriously influenced.
Therefore, it is an urgent need to solve the problem in the art to provide a method for improving the stability of the air interface synchronization state in the low snr environment without increasing the hardware cost of the base station and with low implementation complexity.
Disclosure of Invention
The invention provides an air interface synchronization method and system for an indoor substation base station, which are used for solving the defect that when a small and medium-sized or miniature base station adopts an air interface synchronization mode in an indoor substation scene in the prior art, due to the fact that the downlink signal-to-noise ratio of a synchronization frequency point is deteriorated, the air interface synchronization is difficult to recover after being out of step.
In a first aspect, the present invention provides an air interface synchronization method for an indoor division base station, including:
acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information, and intercepting wireless frame data;
acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;
acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage based on the frame header relative offset value;
determining a timing reference adjustment strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintenance stage;
and if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times, performing self-adaptive pre-compensation.
According to the air interface synchronization method for the indoor branch base station, synchronization information sent by a synchronization source base station is obtained, a downlink timing reference is determined based on the synchronization information, and wireless frame data are intercepted, and the method comprises the following steps:
determining an air interface time sequence of an air interface data stream and the position of a synchronous signal in a wireless frame based on the synchronous information, calculating to obtain a frame header starting position of a synchronous source base station, and taking the frame header starting position of the synchronous source base station as the downlink timing reference;
and intercepting a plurality of wireless frame data from the air interface data stream based on the downlink timing reference.
According to the air interface synchronization method for the indoor distribution base station, provided by the invention, 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, and the method comprises the following steps:
performing time-frequency conversion on the wireless frame data to obtain a corresponding downlink reference signal;
calculating resource block RB data occupied by the downlink reference signal based on Discrete Fourier Transform (DFT) channel estimation to obtain noise energy RIP;
and obtaining a plurality of initial SNR statistics by the RIP, and accumulating the initial SNR statistics and then averaging to obtain the SNR threshold.
According to the air interface synchronization method for the indoor distribution base station, provided by the invention, based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintenance stage, a timing reference adjustment strategy is determined, and the method comprises the following steps:
if the real-time synchronization state is synchronization and the signal-to-noise ratio of the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, negating the frame header relative offset value to obtain a first non-zero adjustment value, adjusting the current timing reference position by using the first non-zero adjustment value as an adjustment step length, and storing the first non-zero adjustment value to a cyclic array with a preset length;
if the real-time synchronization state is synchronization and the signal-to-noise ratio of the synchronization maintenance stage is smaller than the signal-to-noise ratio threshold, accumulating the frame header relative offset value to obtain an accumulated value, when the accumulated value reaches an adjustment threshold, negating the accumulated value to obtain a second non-zero adjustment value, adjusting the current timing reference position by using the second non-zero adjustment value as an adjustment step length, storing the second non-zero adjustment value to a cyclic array with a preset length, and resetting the accumulated value;
if the real-time synchronization state is out-of-step and the signal-to-noise ratio of the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, accumulating the frame header relative deviation value and not adjusting the current timing reference position;
and if the real-time synchronization state is out-of-step and the signal-to-noise ratio of the synchronization maintaining stage is smaller than the signal-to-noise ratio threshold, not processing.
According to the air interface synchronization method for the indoor substation provided by the invention, if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle number, self-adaptive pre-compensation is carried out, and the method comprises the following steps:
accumulating a plurality of adjustment values in the cyclic array to obtain a first accumulated value, taking the number of the plurality of adjustment values as a first pre-compensation period, adjusting the current timing reference position based on the first accumulated value and the first pre-compensation period, and determining the current synchronization state after the first pre-compensation period is finished;
if the first accumulated value is 0, removing the last adjustment value in the plurality of adjustment values, accumulating the rest adjustment values to obtain a second accumulated value, taking the number of the plurality of adjustment values minus 1 as a second pre-compensation period, adjusting the current timing reference position based on the second accumulated value and the second pre-compensation period, and determining the current synchronization state after the second pre-compensation period is finished;
and by analogy, if the real-time synchronization state is out-of-step in the current pre-compensation period, entering the next pre-compensation period to continue pre-compensation.
The air interface synchronization method for the indoor division base station further comprises the following steps:
and if the real-time synchronous states are synchronous in the continuous preset number detection periods after the current pre-compensation period is finished, closing the self-adaptive pre-compensation and recovering the timing reference adjustment mechanism.
In a second aspect, the present invention further provides an air interface synchronization system for an indoor distribution base station, including:
the first processing module is used for acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information and intercepting wireless frame data;
the second processing module is used for acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;
a third processing module, configured to obtain a downlink air interface signal according to a preset period, obtain 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 obtain a signal-to-noise ratio in a synchronization maintenance stage based on the frame header relative offset value;
the adjusting module is used for determining a timing reference adjusting strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintaining stage;
and the pre-compensation module is used for carrying out self-adaptive pre-compensation if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times.
In a third aspect, the present invention further provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of any one of the above-mentioned air interface synchronization methods for a indoor division base station when executing the program.
In a fourth aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the air interface synchronization method of the indoor base station as described in any one of the above.
In a fifth aspect, the present invention further provides a computer program product, including a computer program, where the computer program is executed by a processor to implement the steps of any one of the above-mentioned air interface synchronization methods for a indoor distribution base station.
According to the air interface synchronization method and system for the indoor branch base station, provided by the invention, the downlink signal of the synchronization source base station is periodically detected, the detection result is periodically counted, the frame header offset is estimated, and the timing reference of the indoor branch base station is subjected to self-adaptive precompensation adjustment after the synchronization state is lost in the low signal-to-noise ratio environment, so that the air interface synchronization state is maintained, auxiliary synchronization equipment such as a GPS (global positioning system) is not needed, the radio frequency channel is not frequently switched due to frequent replacement of synchronization frequency points, the stability of the air interface synchronization state of the indoor branch base station in the complex environment is effectively improved on the premise of not increasing the hardware cost of the base station and realizing low complexity, and the application scene range of the indoor branch base station is expanded.
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In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of an air interface synchronization method for a indoor branch base station according to the present invention;
FIG. 2 is a schematic flow chart of a timing reference adjustment strategy provided by the present invention;
FIG. 3 is a schematic flow chart of the adaptive precompensation provided by the present invention;
fig. 4 is a schematic structural diagram of an air interface synchronization system of a indoor branch base station provided in the present invention;
fig. 5 is a schematic structural diagram of an electronic device provided in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Aiming at the problems in the prior art, the invention provides an air interface synchronization keeping method under a low signal-to-noise ratio environment for an indoor small or micro base station, so as to solve the problem that the original air interface synchronization scheme is difficult to restore after the synchronization state is lost under the low signal-to-noise ratio environment.
Fig. 1 is a schematic flow chart of an air interface synchronization method for a indoor branch base station, which, as shown in fig. 1, includes:
step S1, 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;
in the initial synchronization stage, after the synchronization information of the synchronization source base station is acquired, the indoor sub base station sets the downlink timing reference of the indoor sub base station through the internal clock control unit, and meanwhile, intercepts the wireless frame data.
Step S2, acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;
and acquiring the signal-to-noise ratio of the intercepted wireless frame data in the initial synchronization stage through a channel estimation unit, and averaging after accumulating the calculation results to obtain the signal-to-noise ratio threshold.
Step S3, acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage based on the frame header relative offset value;
after entering the synchronization maintenance stage, the indoor sub-base station periodically detects a downlink air interface signal through an air interface interception unit, obtains a real-time synchronization state and a relative offset value between the real-time synchronization state and a frame header of a synchronization source base station, and obtains a signal-to-noise ratio of the synchronization maintenance stage through a channel estimation unit.
Step S4, based on the real-time synchronization status and the comparison result between the SNR and the SNR threshold in the synchronization maintenance phase, determining a timing reference adjustment strategy;
and the indoor division base station selects a timing reference adjustment strategy according to the real-time synchronization state and the result of comparing the real-time signal-to-noise ratio with the signal-to-noise ratio threshold.
Step S5, if the real-time synchronization status is determined to be out of synchronization and synchronization is not recovered within a preset detection cycle, performing adaptive pre-compensation.
If the real-time synchronization state is out-of-step and the synchronization is not recovered for a plurality of detection periods, the indoor sub-base station performs self-adaptive pre-compensation on the timing reference offset.
According to the invention, the downlink signal of the synchronization source base station is periodically detected, the detection result is periodically counted and the frame head offset is estimated, and the timing reference of the indoor sub-base station is subjected to self-adaptive precompensation adjustment after the synchronization state is lost in the low signal-to-noise environment, so that the air interface synchronization state is maintained, auxiliary synchronization equipment such as a GPS (global positioning system) and the like are not needed, and the radio frequency channel is not needed to be frequently switched due to frequent replacement of the synchronization frequency point, so that the stability of the air interface synchronization state of the indoor sub-base station in the complex environment is effectively improved and the application scene range of the indoor sub-base station is expanded on the premise of not increasing the hardware cost of the base station and realizing low complexity.
Based on the above embodiment, step S1 includes:
determining an air interface time sequence of an air interface data stream and the position of a synchronous signal in a wireless frame based on the synchronous information, calculating to obtain a frame header starting position of a synchronous source base station, and taking the frame header starting position of the synchronous source base station as the downlink timing reference;
and intercepting a plurality of wireless frame data from the air interface data stream based on the downlink timing reference.
Specifically, the invention proposes a downlink timing reference MFC in the initial synchronization phaseinitThe clock control unit in the indoor sub-base station calculates the initial position of the frame header of the synchronization source base station according to the 3GPP protocol according to the initial synchronization information of the synchronization source base station, namely the air interface time sequence and the position of the synchronization signal in the wireless frame, so as toThis is set as the time reference for the cell base station.
And then intercepting the data of the wireless frame, and intercepting N complete wireless frame data lengths from the air interface data stream received in the initial synchronization stage according to the result of successful primary synchronization, wherein N > is 1.
The invention determines the downlink timing reference in the initial synchronization stage, intercepts the wireless frame data and is used as the reference for adjusting the subsequent real-time synchronization state, and has the characteristics of convenient acquisition and no need of depending on hardware.
Based on any of the above embodiments, step S2 includes:
performing time-frequency conversion on the wireless frame data to obtain a corresponding downlink reference signal;
calculating resource block RB data occupied by the downlink reference signal based on Discrete Fourier Transform (DFT) channel estimation to obtain noise energy RIP;
and obtaining a plurality of initial SNR statistics by the RIP, and accumulating the initial SNR statistics and then averaging to obtain the SNR threshold.
Specifically, when further calculating the signal-to-noise ratio at the initial synchronization stage, first, time-frequency conversion processing is performed on the N truncated complete radio frames, then, corresponding downlink reference signals are extracted and input to the channel estimation unit, noise energy (RIP) is calculated, and then, the signal-to-noise ratio (SNR) is obtained, and the signal-to-noise ratio threshold calculation mode is to calculate the average value after accumulating the N obtained initial signal-to-noise ratio statistics.
Taking a TD-LTE base station as an example, firstly segmenting the intercepted N wireless frame data according to the length of the system wireless frame, respectively performing cyclic prefix removal and FFT operation processing on the data of the subframe 1 or the subframe 9 in each 10ms wireless frame by using a time domain symbol as a unit, then extracting Resource Block (RB) data occupied by a downlink reference signal from the data, inputting the Resource Block (RB) data into a channel estimation unit, obtaining noise energy (RIP) through DFT channel estimation, further obtaining a signal-to-noise ratio (SNR), and finally obtaining a signal-to-noise ratio threshold δ by averaging after accumulating the obtained N initial signal-to-noise ratio statistics.
Here, air interface listening unit detectsThe period can be set to 2nMultiplied by 10ms, where n>0 and n<N is an integer of 5.
The invention calculates the SNR and SNR threshold of the initial synchronization stage as the basis for judging whether the system needs real-time synchronization, and has the characteristics of simple calculation, convenient implementation and the like without using extra hardware resources as support.
Based on any of the above embodiments, step S3 includes:
if the real-time synchronization state is synchronization and the signal-to-noise ratio of the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, negating the frame header relative offset value to obtain a first non-zero adjustment value, adjusting the current timing reference position by using the first non-zero adjustment value as an adjustment step length, and storing the first non-zero adjustment value to a cyclic array with a preset length;
if the real-time synchronization state is synchronization and the signal-to-noise ratio of the synchronization maintenance stage is smaller than the signal-to-noise ratio threshold, accumulating the frame header relative offset value to obtain an accumulated value, when the accumulated value reaches an adjustment threshold, negating the accumulated value to obtain a second non-zero adjustment value, adjusting the current timing reference position by using the second non-zero adjustment value as an adjustment step length, storing the second non-zero adjustment value to a cyclic array with a preset length, and resetting the accumulated value;
if the real-time synchronization state is out-of-step and the signal-to-noise ratio of the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, accumulating the frame header relative deviation value and not adjusting the current timing reference position;
and if the real-time synchronization state is out-of-step and the signal-to-noise ratio of the synchronization maintaining stage is smaller than the signal-to-noise ratio threshold, not processing.
Specifically, as shown in fig. 2, the timing reference adjustment strategy according to the present invention specifically includes:
(1) when the real-time state is synchronous and the SNR is higher than or equal to the SNR threshold delta, the air interface synchronization result has the highest confidence coefficient, and the internal clock control unit has MFC for the periodically detected frame header relative deviation valueoffsetTaking the inverse as the step length to instantly adjust the currentTiming the reference position and adjusting the non-zero value (-MFC)offset) Saving to a cyclic array a with the length of L;
(2) when the real-time state is synchronous and the SNR is lower than the SNR threshold delta, the internal clock control unit MFC detects the frame head relative deviation value periodicallyoffsetAccumulating, when the absolute value of the accumulated value reaches the regulation threshold beta, the internal clock control unit will accumulate the MFCsumTaking the inverse as the step length to adjust the current timing reference position, and adjusting the value (-MFC)sum) Saving to a circulation array a, and simultaneously, returning the accumulated value to zero;
(3) when the real-time state is out of step and the SNR is higher than or equal to the SNR threshold, only accumulating the frame header relative deviation value, and not adjusting the timing reference position;
(4) and when the real-time state is out-of-step and the SNR is lower than the signal-to-noise ratio threshold delta, the air interface synchronization result has the lowest confidence coefficient, and no processing is performed at the moment.
Here, the loop array a defaults to store the latest L adjustment values, before each data write, the loop array a adds 1 to the serial numbers of all elements in the loop array a and shifts the contents of the elements 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 overwritten, and finally the current data is stored to the first bit a (0) of the array.
The adjustment threshold β is set to T minimum time units, and the minimum time units are related to the sampling rate of the system, for example, in an LTE system with 20M bandwidth, the 30.72M sampling rate corresponds to β ═ T × (1/30720000) s.
The invention obtains and executes the timing reference adjustment strategy by comprehensively pre-judging the comparison result of the real-time state of the system, the SNR and the SNR threshold, and can flexibly carry out dynamic compensation aiming at the real-time state of the system by setting a plurality of adjustment values and storing the adjustment values by a circulating array.
Based on any of the above embodiments, step S5 includes:
accumulating a plurality of adjustment values in the cyclic array to obtain a first accumulated value, taking the number of the plurality of adjustment values as a first pre-compensation period, adjusting the current timing reference position based on the first accumulated value and the first pre-compensation period, and determining the current synchronization state after the first pre-compensation period is finished;
if the first accumulated value is 0, removing the last adjustment value in the plurality of adjustment values, accumulating the rest adjustment values to obtain a second accumulated value, taking the number of the plurality of adjustment values minus 1 as a second pre-compensation period, adjusting the current timing reference position based on the second accumulated value and the second pre-compensation period, and determining the current synchronization state after the second pre-compensation period is finished;
and by analogy, if the real-time synchronization state is out-of-step in the current pre-compensation period, entering the next pre-compensation period to continue pre-compensation.
Specifically, as shown in fig. 3, the adaptive pre-compensation proposed by the present invention specifically includes:
and accumulating and summing the L adjustment values stored in the current cyclic array to obtain an accumulated value Sum0, adjusting the current timing reference position by the indoor branch base station by taking L as a period and Sum0 as a step length, detecting the current synchronization state after the current precompensation period is finished, and selecting to continue the precompensation process or quit the precompensation process according to the result.
Further, if Sum0 is 0, then continue to calculate Sum1 ═ Σ { a (0), a (1), …, a (L-2) }, change the pre-compensation adjustment step size to Sum1, and the pre-compensation period to L-1.
The invention dynamically adjusts the adjustment value in the cyclic array by adopting the self-adaptive pre-compensation processing flow and aiming at whether the current state of the system meets the synchronization requirement, thereby realizing the real-time synchronous compensation of the system offset.
Based on any embodiment above, still include:
and if the real-time synchronous states are synchronous in the continuous preset number detection periods after the current pre-compensation period is finished, closing the self-adaptive pre-compensation and recovering the timing reference adjustment mechanism.
It should be noted that, after the current pre-compensation period is over, the present invention continues to detect X periods continuously, if the real-time synchronization states are all synchronous, the adaptive pre-compensation is closed, and the indoor sub-base station recovers the timing reference adjustment mechanism to continue to maintain the air interface synchronization state. Where X is a positive integer greater than 0, the present invention assumes that X > -3 and X < L, ensuring that the detection period has a certain number but is not infinite.
According to the method, after the self-adaptive pre-compensation, the periodic detection is continuously supplemented, so that the self-adaptive pre-compensation process is closed after the system enters a stable synchronous state, and system resources are effectively saved.
The air interface synchronization system of the indoor branch base station provided by the invention is described below, and the air interface synchronization system of the indoor branch base station described below and the air interface synchronization method of the indoor branch base station described above can be referred to correspondingly.
Fig. 4 is a schematic structural diagram of an air interface synchronization system of a indoor branch base station, 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, wherein:
the first processing module 41 is 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 42 is configured to obtain an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and obtain a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio; the third processing module 43 is configured to obtain a downlink air interface signal according to a preset period, obtain 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 obtain a signal-to-noise ratio in a synchronization maintenance stage based on the frame header relative offset value; the adjusting module 44 is configured to determine a timing reference adjusting policy based on the real-time synchronization status and a comparison result between the signal-to-noise ratio in the synchronization maintaining stage and the signal-to-noise ratio threshold; the pre-compensation module 45 is configured to perform adaptive pre-compensation if it is determined that the real-time synchronization state is out of synchronization and synchronization is not restored within a preset detection cycle number.
According to the invention, the downlink signal of the synchronization source base station is periodically detected, the detection result is periodically counted and the frame head offset is estimated, and the timing reference of the indoor sub-base station is subjected to self-adaptive precompensation adjustment after the synchronization state is lost in the low signal-to-noise environment, so that the air interface synchronization state is maintained, auxiliary synchronization equipment such as a GPS (global positioning system) and the like are not needed, and the radio frequency channel is not needed to be frequently switched due to frequent replacement of the synchronization frequency point, so that the stability of the air interface synchronization state of the indoor sub-base station in the complex environment is effectively improved and the application scene range of the indoor sub-base station is expanded on the premise of not increasing the hardware cost of the base station and realizing low complexity.
Fig. 5 illustrates a physical structure diagram of an electronic device, which may include, as shown in fig. 5: 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 via the communication bus 540. Processor 510 may invoke logic instructions in memory 530 to perform a method for air interface synchronization of a base station, the method comprising: acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information, and intercepting wireless frame data; acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio; acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage based on the frame header relative offset value; determining a timing reference adjustment strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintenance stage; and if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times, performing self-adaptive pre-compensation.
Furthermore, the logic instructions in the memory 530 may be implemented in the form of software functional units and stored in a computer readable storage medium when the software functional units are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, the present invention further provides a computer program product, where the computer program product includes a computer program, where the computer program is stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, a computer is capable of executing the air interface synchronization method for indoor distributed base stations provided by the foregoing methods, where the method includes: acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information, and intercepting wireless frame data; acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio; acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage based on the frame header relative offset value; determining a timing reference adjustment strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintenance stage; and if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times, performing self-adaptive pre-compensation.
In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program is implemented by a processor to execute the air interface synchronization method of the indoor distributed base station provided by the foregoing methods, and the method includes: acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information, and intercepting wireless frame data; acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio; acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage based on the frame header relative offset value; determining a timing reference adjustment strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintenance stage; and if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times, performing self-adaptive pre-compensation.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. An air interface synchronization method for an indoor division base station is characterized by comprising the following steps:
acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information, and intercepting wireless frame data;
acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data, and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;
acquiring a downlink air interface signal according to a preset period, acquiring a real-time synchronization state and a frame header relative offset value of a synchronization source base station by the downlink air interface signal, and acquiring a signal-to-noise ratio of a synchronization maintenance stage based on the frame header relative offset value;
determining a timing reference adjustment strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintenance stage;
and if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times, performing self-adaptive pre-compensation.
2. The air interface synchronization method for the indoor division base station according to claim 1, wherein the acquiring synchronization information sent by the synchronization source base station, determining a downlink timing reference based on the synchronization information, and intercepting data of the wireless frame comprises:
determining an air interface time sequence of an air interface data stream and the position of a synchronous signal in a wireless frame based on the synchronous information, calculating to obtain a frame header starting position of a synchronous source base station, and taking the frame header starting position of the synchronous source base station as the downlink timing reference;
and intercepting a plurality of wireless frame data from the air interface data stream based on the downlink timing reference.
3. The air interface synchronization method for the indoor distribution base station according to claim 1, wherein 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 comprises:
performing time-frequency conversion on the wireless frame data to obtain a corresponding downlink reference signal;
calculating resource block RB data occupied by the downlink reference signal based on Discrete Fourier Transform (DFT) channel estimation to obtain noise energy RIP;
and obtaining a plurality of initial SNR statistics by the RIP, and accumulating the initial SNR statistics and then averaging to obtain the SNR threshold.
4. The air interface synchronization method for the indoor division base station according to claim 1, wherein determining a timing reference adjustment strategy based on the real-time synchronization status and a comparison result between the signal-to-noise ratio at the synchronization maintenance stage and the signal-to-noise ratio threshold comprises:
if the real-time synchronization state is synchronization and the signal-to-noise ratio of the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, negating the frame header relative offset value to obtain a first non-zero adjustment value, adjusting the current timing reference position by using the first non-zero adjustment value as an adjustment step length, and storing the first non-zero adjustment value to a cyclic array with a preset length;
if the real-time synchronization state is synchronization and the signal-to-noise ratio of the synchronization maintenance stage is smaller than the signal-to-noise ratio threshold, accumulating the frame header relative offset value to obtain an accumulated value, when the accumulated value reaches an adjustment threshold, negating the accumulated value to obtain a second non-zero adjustment value, adjusting the current timing reference position by using the second non-zero adjustment value as an adjustment step length, storing the second non-zero adjustment value to a cyclic array with a preset length, and resetting the accumulated value;
if the real-time synchronization state is out-of-step and the signal-to-noise ratio of the synchronization maintenance stage is greater than or equal to the signal-to-noise ratio threshold, accumulating the frame header relative deviation value and not adjusting the current timing reference position;
and if the real-time synchronization state is out-of-step and the signal-to-noise ratio of the synchronization maintaining stage is smaller than the signal-to-noise ratio threshold, not processing.
5. The air interface synchronization method for the indoor branch base station according to claim 4, wherein if the real-time synchronization state is determined to be out of synchronization and synchronization is not recovered within a preset detection cycle number, performing adaptive pre-compensation, including:
accumulating a plurality of adjustment values in the cyclic array to obtain a first accumulated value, taking the number of the plurality of adjustment values as a first pre-compensation period, adjusting the current timing reference position based on the first accumulated value and the first pre-compensation period, and determining the current synchronization state after the first pre-compensation period is finished;
if the first accumulated value is 0, removing the last adjustment value in the plurality of adjustment values, accumulating the rest adjustment values to obtain a second accumulated value, taking the number of the plurality of adjustment values minus 1 as a second pre-compensation period, adjusting the current timing reference position based on the second accumulated value and the second pre-compensation period, and determining the current synchronization state after the second pre-compensation period is finished;
and by analogy, if the real-time synchronization state is out-of-step in the current pre-compensation period, entering the next pre-compensation period to continue pre-compensation.
6. The air interface synchronization method for the indoor branch base station according to claim 1, further comprising:
and if the real-time synchronous states are synchronous in the continuous preset number detection periods after the current pre-compensation period is finished, closing the self-adaptive pre-compensation and recovering the timing reference adjustment mechanism.
7. An air interface synchronization system of an indoor division base station, comprising:
the first processing module is used for acquiring synchronous information sent by a synchronous source base station, determining a downlink timing reference based on the synchronous information and intercepting wireless frame data;
the second processing module is used for acquiring an initial synchronization stage signal-to-noise ratio based on the wireless frame data and acquiring a signal-to-noise ratio threshold according to the initial synchronization stage signal-to-noise ratio;
a third processing module, configured to obtain a downlink air interface signal according to a preset period, obtain 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 obtain a signal-to-noise ratio in a synchronization maintenance stage based on the frame header relative offset value;
the adjusting module is used for determining a timing reference adjusting strategy based on the real-time synchronization state and the comparison result of the signal-to-noise ratio and the signal-to-noise ratio threshold in the synchronization maintaining stage;
and the pre-compensation module is used for carrying out self-adaptive pre-compensation if the real-time synchronization state is judged to be out of step and synchronization is not recovered within the preset detection cycle times.
8. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the air interface synchronization method of the indoor branch base station according to any one of claims 1 to 6 when executing the program.
9. A non-transitory computer readable storage medium, having a computer program stored thereon, wherein the computer program, when being executed by a processor, implements the steps of the air interface synchronization method for the indoor base stations according to any one of claims 1 to 6.
10. A computer program product comprising a computer program, wherein the computer program, when executed by a processor, implements the steps of the method for air interface synchronization of a indoor base station according to any of claims 1 to 6.
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| PCT/CN2022/103782 WO2023087738A1 (en) | 2021-11-16 | 2022-07-05 | Air interface synchronization method and system for indoor distribution base station |
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| WO2023087738A1 (en) * | 2021-11-16 | 2023-05-25 | 中信科移动通信技术股份有限公司 | Air interface synchronization method and system for indoor distribution base station |
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