Disclosure of Invention
In view of the above, it is necessary to provide a highly reliable signal synchronization detection method, device, apparatus and system.
In order to achieve the above object, in one aspect, an embodiment of the present invention provides a signal synchronization detection method, including:
performing time domain correlation processing on the received air interface signal to obtain a time domain correlation sequence;
acquiring each power value of the time domain correlation sequence, screening out sequence points with the power values larger than a preset correlation threshold value, and obtaining a correlation peak sequence according to the screened sequence points;
processing the related peak sequences according to a preset screening rule to obtain each combined peak sequence; the preset screening rule comprises that the preset symbol length is used as a screening interval and the NPSS circulating transmission times are used as screening quantity;
if the number of the nonzero peak values in the combined peak sequence is larger than the threshold value of the number of the peak values, the combined peak sequence is determined to be an effective combined peak sequence;
obtaining the maximum matching power of the effective combined peak sequence;
comparing the maximum matching powers to obtain a maximum combined peak power value;
and when the synchronous signal is detected in the air interface signal according to the maximum combined peak power value, determining a signal synchronous detection position point and acquiring a timing deviation.
In one embodiment, the step of obtaining the maximum matching power of the valid combined peak sequence comprises:
based on the cyclic prefix sequence, carrying out cyclic prefix position matching processing on the effective combined peak sequence to obtain the matching power of the effective combined peak sequence;
and comparing the matching powers of the effective combined peak sequences to obtain the maximum matching power.
In one embodiment, the timing offset is a time advance;
when the synchronous signal is detected in the air interface signal according to the maximum combined peak power value, the steps of determining the synchronous detection position point of the synchronous signal and acquiring the timing deviation comprise:
acquiring a synchronous detection position point and a time lead of a synchronous signal according to the serial number and the sign bit;
the sequence number is the sequence number of the effective combined peak sequence corresponding to the maximum combined peak power value; the sign bit is the position of the peak value corresponding to the maximum combined peak power value in the corresponding effective combined peak sequence.
In one embodiment, the threshold number of peaks is 4, or 5, or 6.
In one embodiment, the step of performing time-domain correlation on the air interface signal to obtain a time-domain correlation sequence includes:
generating a local NPSS synchronization signal;
and performing blind correlation operation on the air interface signal by adopting a local NPSS synchronous signal to obtain a time domain correlation sequence.
In one embodiment, the correlation threshold is the product of the power up factor and the average power of the low correlation sequence or the product of the power degradation factor and the average power of the high correlation sequence;
the step of screening each power value based on the correlation threshold value to obtain the correlation peak sequence comprises the following steps:
sequencing the power values according to the magnitude sequence to obtain a power value sequence;
and intercepting the power value sequence according to the preset power value number to obtain a low correlation sequence or a high correlation sequence.
In one embodiment, the step of confirming that the synchronization signal is detected in the air interface signal according to the maximum combined peak power value includes:
and when the maximum combined peak power value is larger than or equal to the detection power threshold value, confirming that the synchronous signal is detected in the air interface signal.
On the other hand, an embodiment of the present invention further provides a signal synchronization detection apparatus, including:
the time domain correlation sequence module is used for carrying out time domain correlation processing on the received air interface signal to obtain a time domain correlation sequence;
the correlation peak sequence module is used for acquiring each power value of the time domain correlation sequence, screening out sequence points with the power values larger than a preset correlation threshold value, and obtaining a correlation peak sequence according to the screened sequence points;
the combined peak sequence module is used for processing the related peak sequences according to a preset screening rule to obtain each combined peak sequence; the preset screening rule comprises that the preset symbol length is used as a screening interval and the NPSS circulating transmission times are used as screening quantity;
the effective combined peak sequence confirming module is used for confirming that the combined peak sequence is an effective combined peak sequence if the number of the nonzero peak values in the combined peak sequence is larger than a peak value number threshold value;
the maximum matching power acquisition module is used for acquiring the maximum matching power of the effective combined peak sequence;
the maximum combined peak power value module is used for comparing the maximum matching powers to obtain a maximum combined peak power value;
and the timing deviation acquisition module is used for determining a synchronous detection position point of the synchronous signal and acquiring the timing deviation when the synchronous signal is detected in the air interface signal according to the maximum combined peak power value.
A communication device is used for executing the steps of the signal synchronization detection method.
In one embodiment, the communication device is an NB-IoT terminal or an NB-IoT base station.
A signal synchronous detection system comprises at least two communication devices which are connected with each other; the communication equipment is used for executing the steps of the signal synchronization detection method.
In one embodiment, the communication device is an NB-IoT terminal or an NB-IoT base station.
A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the above-mentioned signal synchronization detection method.
One of the above technical solutions has the following advantages and beneficial effects:
according to the method and the device, the maximum combined peak power value is obtained by carrying out a series of processing on the air interface signal, and further, when the synchronous signal is detected in the air interface signal according to the maximum combined peak power value, the synchronous detection position point of the synchronous signal can be accurately determined and the timing deviation can be obtained, so that the reliability is high.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The signal synchronization detection method can be applied to the signal detection synchronization process of various communication devices. Specifically, the method can be applied to the process of cell search access in which a terminal is connected to a base station, and can also be applied to the process of cell search access in which a base station is connected to another base station. Further, the method can be widely applied to wireless communication systems of narrowband NB-IoT systems. In the application scenario, the signal synchronization detection method provided by the present application can be embodied from a signal processing flow.
The communication equipment can be but is not limited to various personal computers, notebook computers, smart phones, tablet computers and portable wearable equipment if the communication equipment is a terminal; further, it may be an NB-IoT terminal. If the communication device is a base station, the communication device may be, but is not limited to, various macro base stations, micro base stations, pico base stations, and distributed base stations, and further, the base station may be an NB-IoT base station.
In one embodiment, as shown in fig. 1, a signal synchronization detecting method is provided, which is described by taking an example of the method applied to a communication device, and includes the following steps:
step S102, the received air interface signal is processed by time domain correlation to obtain a time domain correlation sequence.
When the communication device is a base station, an air interface signal sent by another base station can be received; when the communication device is a terminal, an air interface signal sent from the base station may be received.
And step S104, acquiring each power value of the time domain correlation sequence, screening out sequence points with the power values larger than a preset correlation threshold value, and obtaining a correlation peak sequence according to the screened sequence points.
And step S106, processing the related peak sequences according to a preset screening rule to obtain each combined peak sequence.
The preset screening rule comprises the steps of taking the preset symbol length as a screening interval and taking the NPSS circulating transmission times as the screening quantity.
And step S108, if the number of the nonzero peak values in the combined peak sequence is larger than the threshold value of the number of the peak values, determining that the combined peak sequence is an effective combined peak sequence.
The threshold value of the number of peaks may be 4, 5, or 6.
Step S110, obtain the maximum matching power of the effective combined peak sequence.
The maximum matching power may be obtained by performing cyclic prefix position matching on the effective combined peak sequence and then comparing the cyclic prefix position matching with the effective combined peak sequence.
And step S112, comparing the maximum matching powers to obtain a maximum combined peak power value.
Specifically, each maximum matching power corresponds to each valid combined peak sequence. The comparison process can be that two-by-two comparison is carried out one by one, and the maximum value of the maximum matching power is obtained and is used as the maximum combined peak power value.
And step S114, when the synchronous signal is detected in the air interface signal according to the maximum combined peak power value, determining a signal synchronous detection position point and acquiring a timing deviation.
The timing offset may be a Time Advance (TA).
Specifically, the synchronization signal synchronization detection position point and the timing offset may be determined according to the effective combined peak sequence to which the maximum combined peak power value belongs and the position of the maximum combined peak power value in the effective combined peak sequence.
It should be noted that the local NPSS synchronization signal is different from a synchronization signal detected by a following air interface signal, and the local NPSS synchronization signal may be generated in advance and used to process the air interface signal to obtain a signal of the time domain correlation sequence.
In a specific embodiment, the step of performing time-domain correlation processing on the air interface signal to obtain a time-domain correlation sequence includes:
generating a local NPSS (narrow band Primary Synchronization Signal, namely a cell downlink Synchronization Signal) Synchronization Signal;
and performing blind correlation operation on the air interface signal by adopting a local NPSS synchronous signal to obtain a time domain correlation sequence.
Specifically, if the local NPSS synchronization signal is d (n), the air interface signal is r (n), and the time domain correlation sequence C is seti(i ═ 1,2, …, N) can be obtained by the following formula:
wherein i is a data index; and N is the length of the time domain correlation sequence obtained by sliding according to the formula, wherein the sliding refers to the sliding of an air interface signal R (N + i) in the process that i is increased from 1 to N.
In the signal synchronization detection method, the maximum combined peak power value is obtained by performing a series of processing on the air interface signal, so that when the synchronization signal is detected in the air interface signal according to the maximum combined peak power value, the synchronization detection position point of the synchronization signal can be accurately determined and the timing deviation can be obtained, and the reliability is high.
In one embodiment, as shown in fig. 2, a signal synchronization detecting method is provided, which is described by taking the method as an example for a communication device, and includes the following steps:
in step S202, a local NPSS synchronization signal is generated.
And step S204, performing blind correlation operation on the air interface signal by adopting a local NPSS synchronous signal to obtain a time domain correlation sequence.
Step S206, each power value of the time domain correlation sequence is obtained, sequence points with power values larger than a preset correlation threshold value are screened out, and a correlation peak sequence is obtained according to the screened sequence points.
Specifically, a time domain correlation sequence C is obtainediRespective power value P ofiThe step (2) can be realized by the following formula:
Pi=‖Ci‖2
the above formula calculates the complex data C by the square of the absolute valueiOf the power of (c).
And S208, processing the related peak sequences according to a preset screening rule to obtain each combined peak sequence.
The preset screening rule comprises the steps of taking the preset symbol length as a screening interval and taking the NPSS circulating transmission times as the screening quantity.
Based on the correlation threshold value PTHFor each power value PiScreening to obtain related peak sequence CSiThis can be achieved by the following equation:
setting the screening quantity as L and the preset symbol length as D; wherein L may be 11 and D may be 128+ 9;
processing related peak sequences CS according to a preset screening ruleiObtaining each combined peak sequence YaThis can be achieved by the following equation:
Ya={CSa,CSa+D,…,CSa+(L-1)×D}
wherein a is the sequence number of each combined peak sequence, and different a values represent different combined peak sequences and correspond to the sequence number j above; CSa,CSa+D,…,CSa+(L-1)×DFor each equally spaced peak in the sequence of correlation peaks, with CS aboveiCorresponding; a. a + D and a + (L-1). times.D are CSiDifferent values of the data index i represent that each equally spaced peak is in the related peak sequence CSiOf (c) is used.
In step S210, if the number of non-zero peak values in the combined peak sequence is greater than the threshold value of the number of peak values, the combined peak sequence is determined to be an effective combined peak sequence.
Step S212, based on the cyclic prefix sequence, the cyclic prefix position matching processing is carried out on the effective combined peak sequence to obtain the matching power of the effective combined peak sequence.
Wherein, the cyclic prefix sequence may be Sl(l=1~L)={1,1,1,1,-1,-1,1,1,1,-1,1}。
Specifically, the effective combined peak sequence is Z
j(j represents Z)
jThe sequence number in each combined peak sequence) and further obtain each matching power according to the difference of the initial sign bit k corresponding to S
Wherein Z
j,eRepresents Z
jE is the position index; l' represents Z
jThe maximum position of the mid non-zero peak; l is a signal cyclic transfer characteristic, which may be 11; the value of k + e needs to be guaranteed to be less than or equal to the length of the cyclic prefix sequence S in order to avoid calculation errors.
Step S214, comparing the matching powers of the effective combined peak sequences to obtain the maximum matching power.
In the comparison process, each matching power can be compared pairwise, and the maximum value in each matching power is obtained and used as the maximum matching power.
In particular, maximum matching power
And step S216, comparing the maximum matching powers to obtain a maximum combined peak power value.
In the comparison process, the maximum matching powers can be compared pairwise, and the maximum value in the matching powers is obtained and used as the maximum matching power.
In particular, the maximum combined peak power value
Since there are a plurality of valid combination peak sequences and a plurality of maximum matching powers are obtained in step S214, the maximum matching powers can be compared in this step.
In step S218, when the maximum combined peak power value is greater than or equal to the detection power threshold value, it is determined that the synchronization signal is detected in the air interface signal.
Specifically, the detection power threshold is set to
In that
And if not, re-executing the steps.
Step S220, the timing deviation is the time advance; and acquiring a synchronous detection position point and a time lead of the synchronous signal according to the serial number and the sign bit.
Wherein, the sequence number is the sequence number of the effective combined peak sequence corresponding to the maximum combined peak power value; further, sequence number is ZjSequence number j in each combined peak sequence.
The sign bit is the position of the maximum combined peak power value in the corresponding effective combined peak sequence; further, the sign bit refers to the matching power MP corresponding to the maximum combined peak power valuekThe start sign bit k. Specifically, the timing advance TA is j-k × D; d can be derived from the cyclic transmission characteristic (NPSS cyclic transmission number) of the synchronization signal.
In a specific embodiment, the correlation threshold is the product of the power up factor and the average power of the low correlation sequence or the product of the power degradation factor and the average power of the high correlation sequence; the step of screening each power value based on the correlation threshold value to obtain the correlation peak sequence comprises the following steps:
sequencing the power values according to the magnitude sequence to obtain a power value sequence;
and intercepting the power value sequence according to the preset power value number to obtain a low correlation sequence or a high correlation sequence.
Specifically, the sorting according to the size sequence can be arranged from small to large, and can also be arranged from large to small; meanwhile, according to the number of preset power values, a power value sequence can be intercepted from small to large to obtain a low correlation sequence; the power value sequence can also be intercepted from large to small to obtain a high correlation sequence;
setting the preset power value number as X and the power value sequence as
The power up factor is alpha and the average power of the low correlation sequence is
And then the correlation threshold value P
THThis can be obtained from the following equation:
wherein α is 1 to 10.
Or the preset power value number is X, and the power value sequence is
The power up factor is beta and the average power of the highly correlated sequences is
And then the correlation threshold value P
THCan be obtained by the following formula:
wherein beta is between 0.1 and 1.
In the signal synchronous detection method, a correlation peak sequence is obtained by screening a time domain correlation sequence, and then the correlation peak sequence is further screened to obtain each combined peak sequence, so as to obtain an effective combined peak sequence; and then screening the combined peak sequence to obtain an effective combined peak sequence. After screening is finished, calculating each matching power and comparing to obtain a maximum combined peak power value, confirming a synchronous signal according to the maximum combined peak power value, and finally determining a synchronous detection position point of the synchronous signal and obtaining a time lead. Through the processes of multiple screening and power calculation comparison, the detection accuracy of the synchronous signals is effectively guaranteed, the errors of the obtained synchronous detection position points and the time lead of the synchronous signals are reduced, and the reliability is high.
Other technical features in this embodiment are the same as those in the above embodiments, and are not described herein again.
The present embodiment will be described with reference to a specific example.
A signal synchronization detecting method shown in fig. 3, which is described by taking the method as an example applied to a communication device, includes the following steps:
step S302, the received signal and the local NPSS synchronous signal are subjected to time domain correlation, and a time domain correlation sequence is obtained.
And step S304, screening the time domain correlation sequence to obtain a correlation peak sequence.
Step S306, each correlation peak and the equal interval peak are taken, and when the non-zero peak value is larger than the threshold value of the number of the peak values, an effective combined peak sequence is obtained.
Step S308, the cyclic prefix position matching is carried out on each effective combined peak sequence to obtain each matching power of the effective combined peak sequence, and further the maximum matching power of the effective combined peak sequence is obtained.
Step S310, comparing the maximum matching power values of all effective combined peaks to obtain the maximum combined peak power value.
And step S312, judging and detecting the effectiveness of the NPSS according to the maximum combined peak power value.
Step S314, determining NPSS synchronous detection position points according to the combined peak of the maximum combined peak power value, and calculating the timing deviation.
The received signal is an air interface signal sent by the base station.
In a specific example, a time domain correlation sequence C is obtained by blind correlation operation of a pre-generated local NPSS synchronization signal d (n) and an air interface receiving signal R (n)i(i=1,2,…,N):
N is the sliding correlation sequence length (128 data are correlated at one time by sliding to obtain one correlation value); n is the signal data index.
In a specific example, the power values P are calculated firsti=‖Ci‖2Then setting a correlation threshold value PTHScreening out power values which are greater than or equal to a correlation threshold value to form a correlation peak sequence:
in a specific example, according to NPSS cycle L-11 transmission characteristics, the theoretically possible peak positions are spaced at a fixed symbol length D-128 +9, and the combined peak sequences are Ya={CSa,CSa+D,…,CSa+(L-1)*D};
For combined peak sequence YaCounting the number of the included non-zero peak values, if the number of the peak values is larger than a certain threshold value M of the number of the peak valuesTHThen the combined peak sequence is considered as effective, and an effective combined peak sequence Z is obtainedjFurther according to each YaCan obtain each Zj;MTHAnd can be set to be 4-6.
In one specific example, by effectively combining the peak sequences Z
jAnd a cyclic prefix sequence S
l(1 to L) are multiplied to calculate each matching power
Then according to each matched power MP
kObtaining maximum matching power
k indicates the corresponding start sign bit in the cyclic prefix sequence at each multiplication computation.
In one specific example, the maximum combined peak power value is formulated by the formula
And (4) determining.
In a specific example, if
The NPSS signal is considered to be detected in the received signal, otherwise, it is not detected. Wherein
To detect the power threshold, the power control unit, further,
may be the NPSS detection power threshold.
In a specific example, the timing offset (which may be a timing advance) TA is calculated according to the sequence number j of the valid combined peak sequence corresponding to the maximum combined peak power value and the start sign bit k corresponding to the maximum matching power of the valid combined peak sequence.
In one specific example, a correlation threshold value P is setTHComprises the following steps:
by time domain power value P
iThe power value sequence is obtained by sorting the sizes
It is possible to delimit the rise value by calculating the mean power of the X low power values (mean power of the low correlation sequence)
Wherein alpha is a preset power-up factor; it is also possible to delimit the degradation value by calculating the average power of the X high power values (average power of the high correlation sequences)
Where β is a preset power degradation factor.
Wherein, the power value sequence is arranged according to the power value; the smallest X power values are selected as the X low power values, or the largest X power values are selected as the X high power values.
The signal synchronization detection method utilizes the cyclic transmission characteristics of the NPSS multiple symbols to carry out combined peak joint synchronization detection judgment, improves the detection performance and has high reliability.
It should be understood that, although the steps in the flowcharts of fig. 1 to 3 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 1-3 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performing the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.
In one embodiment, as shown in fig. 4, there is provided a signal synchronization detecting apparatus including:
a time domain correlation sequence module 401, configured to perform time domain correlation processing on the received air interface signal to obtain a time domain correlation sequence;
a correlation peak sequence module 403, configured to obtain each power value of the time domain correlation sequence, screen out a sequence point with a power value greater than a preset correlation threshold value, and obtain a correlation peak sequence according to the screened sequence point;
a combined peak sequence module 405, configured to process the related peak sequences according to a preset screening rule to obtain each combined peak sequence; the preset screening rule comprises that the preset symbol length is used as a screening interval and the NPSS circulating transmission times are used as screening quantity;
an effective combined peak sequence confirming module 407, configured to confirm that the combined peak sequence is an effective combined peak sequence if the number of nonzero peak values in the combined peak sequence is greater than a peak value number threshold value;
a maximum matching power obtaining module 409, configured to obtain a maximum matching power of the effective combined peak sequence;
a maximum combined peak power value module 411, configured to compare the maximum matching powers to obtain a maximum combined peak power value;
a timing offset obtaining module 413, configured to determine a synchronization detection location point of the synchronization signal and obtain a timing offset when the synchronization signal is detected in the air interface signal according to the maximum combined peak power value.
In one specific example, the maximum matching power obtaining module 409 includes:
the matching power module is used for carrying out cyclic prefix position matching processing on the effective combined peak sequence based on the cyclic prefix sequence to obtain the matching power of the effective combined peak sequence;
and the maximum matching power module is used for comparing the matching powers of the effective combined peak sequences to obtain the maximum matching power.
In a specific example, the timing offset is a time advance, and the timing offset obtaining module 413 is configured to obtain a synchronization signal synchronization detection location point and the time advance according to a sequence number and a sign bit;
the sequence number is the sequence number of the effective combined peak sequence corresponding to the maximum combined peak power value; the sign bit is the position of the maximum combined peak power value in the corresponding valid combined peak sequence.
In a specific example, the peak count threshold is 4, or 5, or 6.
In a specific example, the time-domain correlation sequence module 401 includes:
the local NPSS synchronizing signal generating module is used for generating a local NPSS synchronizing signal;
and the blind correlation operation module is used for performing blind correlation operation on the air interface signal by adopting the local NPSS synchronous signal to obtain a time domain correlation sequence.
In one specific example, the correlation threshold value is the product of a power up factor and the average power of a low correlation sequence or the product of a power degradation factor and the average power of a high correlation sequence;
further comprising:
the power value sequence module is used for sequencing all power values according to the size sequence to obtain a power value sequence;
and the intercepting module is used for intercepting the power value sequence according to the preset power value quantity to obtain a low correlation sequence or a high correlation sequence.
In a specific example, the method further comprises the following steps:
and the synchronous signal detection confirming module is used for confirming that the synchronous signal is detected in the air interface signal when the maximum combined peak power value is greater than or equal to the detection power threshold value.
For specific limitations of the signal synchronization detecting apparatus, reference may be made to the above limitations of the signal synchronization detecting method, which is not described herein again. The modules in the signal synchronization detection device can be wholly or partially realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
In one embodiment, a communication device is provided, which may be a terminal or a base station, and when the communication device is a terminal, its internal structure diagram may be as shown in fig. 5. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a signal synchronization detection method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.
It will be understood by those skilled in the art that the configuration shown in fig. 5 is a block diagram of only a portion of the configuration associated with the present application, and does not constitute a limitation on the communication device to which the present application is applied, and a particular communication device may include more or less components than those shown in the drawings, or combine certain components, or have a different arrangement of components.
In one embodiment, a communication device is provided, which includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the signal synchronization detection method when executing the computer program.
In one particular example, the communication device is an NB-IoT terminal. Further, it may be an NB-IoT terminal or an NB-IoT base station.
In a specific example, as shown in fig. 6, a signal synchronization detecting system is provided, which includes at least two communication devices (three points in fig. 6 are ellipses, which means a plurality of communication devices) connected to each other, and the communication devices are used for executing the steps of the signal synchronization detecting method.
In one particular example, the communication device is an NB-IoT terminal. Further, it may be an NB-IoT terminal or an NB-IoT base station.
In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the above-mentioned signal synchronization detection method.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.