CN102158933A - Method and device for frequency band searching in TDD-LTE (Time Division Duplex-Long Term Evolution) system - Google Patents
Method and device for frequency band searching in TDD-LTE (Time Division Duplex-Long Term Evolution) system Download PDFInfo
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Abstract
The invention discloses a method for frequency band searching in a TDD-LTE (Time Division Duplex-Long Term Evolution) system and a device for frequency band searching of a terminal/user unit in the TDD-LTE system. The method comprises the steps of: obtaining signals; obtaining signals with respect to a base station on a searched frequency band; estimating strength: estimating strength of each signal with respect to the base station; comparing: comparing the strength of the signal with respect to the base station with a first threshold determined in advance; determining the frequency band: when the strength is more than the first threshold determined in advance, selecting a frequency band where the signals with the strength being more than the first threshold determined in advance, with respect to the base station, as the frequency band to be accessed; and switching the frequency band: when the strength is more than the first threshold determined in advance, switching the searched frequency band, and re-executing the steps for the switched frequency band.
Description
Technical field
Present invention relates in general to wireless communication system, more specifically, relate to a kind of method and apparatus that in TDD-LTE (time division duplex-Long Term Evolution) system, is used for the frequency band search.
Background technology
Along with developing rapidly of mobile communication technology, wireless communication system presents the trend of mobile, broadband and IPization, and the competition in mobile communication market also is growing more intense.For tackling from WiMAX, the challenge of tradition such as Wi-Fi and emerging WiMAX access technology, improve the competitiveness of 3-G (Generation Three mobile communication system) (3G) in broadband wireless access market, 3GPP carries out universal mobile telecommunications system (UMTS) terrestrial wireless and inserts (UTRA) Long Term Evolution (LTE) Study on Technology, to realize 3G technology seamlessly transitting to super 3 g mobile communication system (B3G) and the 4th 4G of third-generation mobile communication system.The improvement target of LTE is to realize higher data rate, shorter time delay, lower cost, higher power system capacity and improved coverage.
The LTE system has defined Frequency Division Duplexing (FDD) (FDD) and time division duplex (TDD) dual mode simultaneously.Two kinds of frame structures of LTE TDD have been unified in 3GPP RAN1 meeting.The fusion of tdd frame structure makes LTE TDD technology be subjected to paying attention to widely.
In wireless communication system, user equipment (UE) need carry out the frequency band search when start, so that find sub-district or the frequency band that is fit to access, thereby is come downlink data receiving and is carried out reliable decoding by this sub-district or frequency band.For the next generation wireless communication system, for example for the LTE system, owing to there is the frequency band of a plurality of work, therefore how correctly finding suitable frequency band to be used to insert is the problem of a key.
Summary of the invention
Provided hereinafter about brief overview of the present invention, so that basic comprehension about some aspect of the present invention is provided.Should be appreciated that this general introduction is not about exhaustive general introduction of the present invention.It is not that intention is determined key of the present invention or pith, neither be intended to limit scope of the present invention.Its purpose only is to provide some notion with the form of simplifying, with this as the preorder in greater detail of argumentation after a while.
According to an aspect of the present invention, provide a kind of method that in the TDD-LTE system, is used for frequency band search, having comprised: the signal obtaining step: obtain on the search frequency band specific to signal of base station; Intensity estimating step: estimate each intensity specific to signal of base station; Comparison step: will compare specific to the intensity and the predetermined first threshold of signal of base station; The frequency band determining step: when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert; Frequency band switch step:, switch search frequency band, and re-execute above-mentioned steps at the frequency band after switching when intensity during less than predetermined first threshold.
According to another aspect of the present invention, provide the frequency band searcher of a kind of TDD-LTE of being used for system terminal/subscriber unit, having comprised: the signal deriving means, its be arranged to obtain on the search frequency band specific to signal of base station; The intensity estimation unit, it is arranged to estimates each intensity specific to signal of base station; Comparison means, it is arranged to intensity and predetermined first threshold specific to signal of base station is compared; Insert frequency band and determine device, it is arranged to when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert; The frequency band switching device shifter, it is arranged to when intensity during less than predetermined first threshold, switches search frequency band.
By according to the solution of the present invention, the interference that nearly allelopathy causes be can when the frequency band that user equipment searches will insert, get rid of reliably, thereby best net synchronization capability and link quality obtained, improve communication quality.
By below in conjunction with the detailed description of accompanying drawing to most preferred embodiment of the present invention, these and other advantage of the present invention will be more obvious.
Description of drawings
The present invention can wherein use same or analogous Reference numeral to represent identical or similar parts in institute's drawings attached by being better understood with reference to hereinafter given in conjunction with the accompanying drawings description.Described accompanying drawing comprises in this manual and forms the part of this specification together with following detailed description, and is used for further illustrating the preferred embodiments of the present invention and explains principle and advantage of the present invention.In the accompanying drawings:
Fig. 1 shows a typical scene that has nearly allelopathy (Near-remote Effect).
Fig. 2 shows the schematic diagram of power measurement of the prior art.
Fig. 3 shows the flow chart that is used for the method for frequency band search according to an embodiment of the invention.
Fig. 4 shows the schematic diagram at the plot planning of the master sync signal of different i values.
Fig. 5 shows the flow chart of the method that is used for the frequency band search according to another embodiment of the invention.
Fig. 6 shows the schematic diagram of frequency band searcher according to an embodiment of the invention.
Fig. 7 shows the schematic diagram of frequency band searcher according to another embodiment of the invention.
Embodiment
To be described one exemplary embodiment of the present invention in conjunction with the accompanying drawings hereinafter.For clarity and conciseness, all features of actual execution mode are not described in specification.Yet, should understand, in the process of any this practical embodiments of exploitation, must make a lot of decisions specific to execution mode, so that realize developer's objectives, for example, meet and system and professional those relevant restrictive conditions, and these restrictive conditions may change to some extent along with the difference of execution mode.In addition, might be very complicated and time-consuming though will also be appreciated that development, concerning the those skilled in the art that have benefited from present disclosure, this development only is customary task.
At this, what also need to illustrate a bit is, for fear of having blured the present invention because of unnecessary details, only show in the accompanying drawings with according to closely-related apparatus structure of the solution of the present invention and/or treatment step, and omitted other details little with relation of the present invention.
The inventor notices, in the TDD-LTE system, the frequency band search is a complicated problems comparatively, because can there be so-called nearly allelopathy in the TDD-LTE system.Fig. 1 is schematically illustrated in the typical scene that subscriber equipment may run in the TDD-LTE system when carrying out the frequency band search.
Figure 1 illustrates a typical scene that has nearly allelopathy (Near-remote Effect).Three sub-district Cell 1, Cell 2 and Cell 3 as can see from Figure 1, they are worked on different frequency band Band 1, Band 2 and Band 3 respectively, and the centre frequency of these three frequency bands is different each other, shown in the last figure among Fig. 2.Wherein the base station of Cell 1 and user equipment (UE) 1 are the most approaching.There is another user equipment (UE) 2 nearby among the sub-district Cell 2.Normally used frequency band searching method is to measure the signal power that receives in the UE1 place in the prior art, and the frequency band that will send maximum signal power is as the frequency band that will insert.Yet in scene shown in Figure 1, may cause problem.Normal, because the base station of UE1 distance C ell 1 is nearest, therefore the power of received Band1 also should be maximum.Yet owing to there is UE2, shown in the figure below among Fig. 2, UE1 can be with the signal of base station power addition from UE2 and Cell 2, this gross power is greater than the signal of base station power from Cell 1 as a result, make UE1 insert Band 2 mistakenly, cause UE1 can not obtain best net synchronization capability and link quality, influence communication efficiency.
First embodiment
The inventor notices that a major reason that causes UE to insert mistakenly in the prior art is interference noise, and this noise may be from other subscriber equipmenies, also may be from other noise sources.Because the signal distinguishing that this interference noise and base station is not sent in the prior art, cause carrying out the power addition of the useful signal that the frequency band search time sends the power and the base station of interference noise simply, thereby cause false judgment easily the frequency band that will insert at subscriber equipment.
The inventor notices that if the distinctive signal that can utilize the base station to send, this distinctive signal is different from noise signal, then can get rid of noise effect when judging the frequency band that will insert when subscriber equipment carries out the frequency band search.
Therefore, according to one embodiment of present invention, a kind of method that is used for the frequency band search has been proposed.Fig. 3 shows the flow chart of this method.
As shown in Figure 3, this method comprises:
S310: obtain on the search frequency band specific to signal of base station;
S330: estimate each intensity specific to signal of base station;
S350: will compare specific to the intensity and the predetermined first threshold of signal of base station;
S370: when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert.
S390:, change search frequency band, and re-execute step S310 at the frequency band after changing when intensity during less than predetermined first threshold.
Owing in said method, used specific to signal of base station, and interference noise does not have sort signal, therefore judge that according to this signal strength signal intensity the frequency band that will insert got rid of the influence of interference noise, can realize inserting more accurately, improve the performance of system.
The applicant further discovers, in the TDD-LTE system, always includes in the downstream signal that send the base station specific to signal of base station, for example PSS (synchronously main) signal and SSS (subsynchronous) signal.Be that example describes with the PSS signal below.It is pointed out that following content is equally applicable to the SSS signal.
Below the PSS signal is simply introduced.
In the LTE system, one has three kinds of PSS signals, from frequency domain, is expressed as the different Zadoff-Chu sequence of parameter.The PSS signal can be represented with following formula:
Wherein parameter i can get 25,29 or 34.
This sequence (length is 62) can be mapped near the centered carrier on the frequency domain 62 subcarriers, and respectively mends 5 zero in both sides, takies 72 subcarriers altogether.In the TDD system, through IFFT conversion (invert fast fourier transformation), the OFDM symbol that comprises PSS can be put into subframe subframe# 1, on the 3rd the OFDM symbol of subframe#6.Because the duration of subframe is 1ms, so the transmission cycle of PSS is 5ms.
More detailed description about PSS and SSS signal can not further describe at this referring to 3GPP standard TS36.211v8.7.0.
As Fig. 4 schematically shows, in actual applications, can be by plot planning so that the employed PSS signal in adjacent base station has different i values.When subscriber equipment is determined from the power of the PSS signal of first base station when maximum, because interference noise does not have the PSS signal, the frequency band that therefore can determine this first base station comparatively exactly is a candidate band preferably, and has got rid of the influence of interference noise.
Hypothesis adopts the PSS signal for to specifically describe specific to signal of base station in the method shown in Fig. 3 below.
Before implementing according to method shown in Figure 3, (i n), wherein has i=0 for the LTE system, 1,2 to have stored the copy PSS of PSS signal in subscriber equipment; N=0,1,2 ..., 127.In addition, obtained the initial center frequency in subscriber equipment, this initial center frequency can also can be the frequency that pre-sets by the outside input.
In step S310, subscriber equipment obtains the sample signal from the base station, and wherein this sample signal comprises the PSS signal.Owing in TDD LTE standard, certainly exist PSS signal in every field (corresponding to 9600 sample points) corresponding to 128 sample points.Preferably, the length of sample signal is not less than 9600+128 sample point.Particularly preferably, the length of sample signal is 9600+128 sample point, so that estimate the intensity of the PSS signal that comprises in this sample signal.Length with sample signal is that 9600+128 describes below.
In step S330, estimate the intensity of PSS signal in each sample signal.Can utilize copy PSS (i, n) intensity of coming PSS signal in the sample estimates signal with the correlation of sample signal in time domain of the PSS signal of storing in the subscriber equipment at this.
Suppose that sample signal is r, then can by following formula calculate sample signal and PSS copy correlation C (i, m):
Wherein C (i, m) m the sample point of expression from sample signal begin afterwards 128 sample points and PSS copy PSS (i, correlation n), m=0,1,2 ..., 9599, r (n+m)
*The conjugation of respective sample point in the expression sample signal.Should be appreciated that the intensity estimation (being correlation here) that can utilize other related operation to obtain the PSS signal.
Owing to all must comprise the PSS signal in each sample signal from different base station, therefore can find corresponding i and definite starting point m by (2) formula for each sample signal, (i n) and under the situation of m can obtain maximum correlation value C at the copy PSS corresponding to this i value
Max(i, m).Those skilled in the art know easily, are obtaining under the situation of maximum correlation value, and the sample point at this m value place is exactly the starting point of the PSS signal in the sample signal.Therefore obtain the PSS signal in the sample signal in this way and be stored in correlation between the PSS signal copy in the subscriber equipment, also just obtained the PSS signal strength signal intensity estimated value in the respective sample signal.
In step S350, determine maximum PSS signal strength signal intensity estimated value, and should maximum PSS signal strength signal intensity estimated value and predetermined first threshold compare.If should maximum PSS signal strength values greater than first threshold, the signal strength signal intensity of frequency band that the PSS signal place of this intensity estimated value maximum then is described can be accepted, therefore in step S370 with the frequency band at the PSS signal place of this intensity estimated value maximum as the frequency band that will insert.If maximum PSS signal strength values less than first threshold, then illustrate this intensity level maximum PSS signal place frequency band signal strength signal intensity too a little less than, so execution in step S390.
In step S390, switch the frequency of the oscillator in the subscriber equipment, make and on other frequency band, obtain sample signal.Subsequently, re-execute step S310.
The inventor notices, after by the oscillator frequency in the switching subscriber equipment all frequency bands having been carried out said method, can determine the frequency band that subscriber equipment will insert by utilizing suitable first threshold usually.Yet under some extreme cases, the maximum PSS signal strength values that subscriber equipment is determined on all frequency bands may be all less than first threshold, then preferably second threshold value can be set this moment, if maximum PSS signal strength values is greater than second threshold value, then directly with the frequency band at maximum PSS signal strength values place as the frequency band that will insert, if maximum PSS signal strength values less than second threshold value, then points out the user not have frequency band to insert.
By the method that is proposed according to the abovementioned embodiments of the present invention, only considered advantageously that being used for frequency band from signal of base station inserts, and for example avoided interference noise influence to a great extent from other subscriber equipmenies.
Second embodiment
The inventor notices, though can as among above-mentioned second embodiment, directly utilize correlation to judge as the signal strength signal intensity of PSS signal, owing to may have the uplink interference signal in the sample signal that receives, therefore may influence judged result.
According to a kind of improvement project of the present invention, can utilize normalized correlation to estimate the signal strength signal intensity of PSS signal.
Normalized correlation is designated as
, can obtain by following formula:
Wherein:
Obtain normalized correlation
Afterwards, be similar to that above-described method is like that same can be provided with corresponding threshold value and to judge, this is not described further.
By utilizing the normalization correlation to estimate the signal strength signal intensity of PSS signal, advantageously overcome the influence of uplink interference signal.
Preferably, estimate for these intensity that obtained
, determine that the maximum intensity in these intensity estimations is estimated
Estimate at maximum intensity
, calculate and use maximum intensity to estimate
Corresponding main synchronizing sequence PSS (i
0) intensity that obtains estimates
, m=0,1,2 ..., 9599 peak-to-average force ratio M.
For example, peak-to-average force ratio M can be maximum intensity estimate with during intensity is estimated and maximum intensity estimate to adopt the ratio of the average of other intensity estimation that identical PSS sequence obtains.Particularly,
As an alternative, peak-to-average force ratio M can be the ratio that maximum intensity is estimated the average of all intensity estimations that identical PSS sequence with employing obtains.Particularly,
Should be appreciated that peak-to-average force ratio M can define according to other calculates.
Obtain after the peak-to-average force ratio M, be similar to that above-described method is same like that can be provided with corresponding threshold value and to judge, this is not described further.
By utilizing peak-to-average force ratio M to estimate the signal strength signal intensity of PSS signal, advantageously overcome the influence of uplink interference signal, and can further improve the accuracy of frequency band search.
The 3rd embodiment
In order further to improve the accuracy for the estimation of PSS signal, preferably, said method according to the present invention can be carried out repeatedly at each frequency band, and judges the frequency band that will insert according to the result who repeatedly carries out.
Fig. 5 shows and according to an embodiment of the inventionly is used to utilize the PSS signal to come the flow chart of the method for search frequency band.
As can see from Figure 5, this method also comprises step S360 on the basis of method shown in Figure 3: judge and whether obtain the number of times of all sample signals greater than predetermined the 3rd threshold value at the current search frequency band, if less than the 3rd threshold value, then once more execution in step S310 so that obtain sample signal r from the current search frequency band once more
kIf, greater than the 3rd threshold value then execution in step S370 to switch search frequency band, so that on other frequency bands, detect.
After the sample signal obtaining step of repeatedly carrying out on the same frequency band, can estimate the signal strength signal intensity of PSS signal in the following manner:
1) directly utilizing correlation to estimate can calculate correlation for the k time repetition under the situation of signal strength signal intensity of PSS signal:
C
k(i, m) in expression i main synchronizing sequence and k the sample sequence from the correlated results of the initial subsequence of m sample, wherein * represents conjugation, m=0,1,2 ..., 9599.
(i n) can calculate maximum related value C for each i value (i=0,1,2) respectively for PSS
K, max(i, m), and with the mean value after this K time repetition
(i, intensity n) is estimated as corresponding PSS signal PSS.Should be appreciated that also can utilize other related operation to obtain intensity estimates.
2) utilizing normalized correlation to estimate under the situation of signal strength signal intensity of PSS signal, for each C
k(i m), estimates C according to intensity
k(i, the intensity of corresponding sample signal m) and N
k(m) intensity is estimated C
k(i, m) normalization obtain normalized intensity and estimate
, wherein
And the mean value that utilizes normalized intensity to estimate
Estimate the intensity of corresponding PSS signal.
3) utilizing peak-to-average force ratio to estimate under the situation of signal strength signal intensity of PSS signal, can estimate according to top these intensity that obtain
, determine that the maximum intensity in these intensity estimations is estimated (being normalized correlation here)
And estimate at maximum intensity
, calculate and use maximum intensity to estimate
Corresponding main synchronizing sequence PSS (i
0) intensity that obtains estimates
, m=0,1,2 ..., 9599 peak-to-average force ratio M.
For example, peak-to-average force ratio M can be maximum intensity estimate with during intensity is estimated and maximum intensity estimate to adopt the ratio of the average of other intensity estimation that identical main synchronizing sequence obtains.Particularly,
For example, peak-to-average force ratio M can be the ratio that maximum intensity is estimated the average of all intensity estimations that identical main synchronizing sequence with employing obtains.Particularly,
Should be appreciated that peak-to-average force ratio M can define according to other calculates.
Because each frequency band of method according to present embodiment has been carried out repeatedly, and judges the frequency band that will insert according to the result who repeatedly carries out, and has therefore further eliminated the influence of other Gaussian noises in the communication system, has improved the accuracy of judging.
Need to prove that according to above-mentioned first to the 3rd embodiment, those skilled in the art can easily be applied to the SSS signal with corresponding method.Because it is more more than PSS signal that the SSS signal has, so computing cost is bigger, yet its principle and above-described method are identical, and this is not described further.
The 4th embodiment
Therefore, according to one embodiment of present invention, the frequency band searcher of a kind of TDD-LTE of being used for system terminal/subscriber unit has been proposed.Fig. 6 shows the schematic diagram of this frequency band searcher.
As shown in Figure 6, this frequency band searcher 600 comprises:
Signal deriving means 610, its be arranged to obtain on the search frequency band specific to signal of base station;
Comparison means 650, it is arranged to intensity and predetermined first threshold specific to signal of base station is compared;
Insert frequency band and determine device 670, it is arranged to when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert.And
Frequency band switching device shifter 690, it is arranged to when intensity during less than predetermined first threshold, changes search frequency band.
Because frequency band searcher 600 has used specific to signal of base station, and interference noise does not have sort signal, therefore judge that according to this signal strength signal intensity the frequency band that will insert got rid of the influence of interference noise, can realize inserting more accurately, improve the performance of system.
The applicant further discovers, in the TDD-LTE system, always includes in the downstream signal that send the base station specific to signal of base station, for example PSS (synchronously main) signal and SSS (subsynchronous) signal.Therefore frequency band searcher 600 can utilize PSS signal or SSS signal as carry out the frequency band search specific to signal of base station.
Hypothesis adopts the PSS signal for to specifically describe specific to signal of base station in frequency band searcher 600 below.
Before frequency band searcher 600 carried out frequency band search, (i n), wherein had i=0 for the LTE system, 1,2 to have stored the copy PSS of PSS signal in subscriber equipment; N=0,1,2 ..., 127.In addition, obtained the initial center frequency in subscriber equipment, this initial center frequency can also can be the frequency that pre-sets by the outside input.
At first, signal deriving means 610 obtains the sample signal from the base station, and wherein this sample signal comprises the PSS signal.Owing in TDD LTE standard, certainly exist PSS signal in every field (corresponding to 9600 sample points) corresponding to 128 sample points.Preferably, the length of sample signal is not less than 9600+128 sample point.Particularly preferably, the length of sample signal is 9600+128 sample point, so that estimate the intensity of the PSS signal that comprises in this sample signal.Length with sample signal is that 9600+128 describes below.
Suppose that sample signal is r, then can by following formula calculate sample signal and PSS copy correlation C (i, m):
Wherein C (i, m) m the sample point of expression from sample signal begin afterwards 128 sample points and PSS copy PSS (i, correlation n), m=0,1,2 ..., 9599, r (n+m)
*The conjugation of respective sample point in the expression sample signal.Should be appreciated that the intensity estimation that can utilize other related operation to obtain the PSS signal.
Owing to all must comprise the PSS signal in each sample signal from different base station, therefore can find corresponding i and definite starting point m by (2) formula for each sample signal, (i n) and under the situation of m can obtain maximum correlation value C at the copy PSS corresponding to this i value
Max(i, m).Those skilled in the art know easily, are obtaining under the situation of maximum correlation value, and the sample point at this m value place is exactly the starting point of the PSS signal in the sample signal.Therefore obtain the PSS signal in the sample signal in this way and be stored in correlation between the PSS signal copy in the subscriber equipment, also just obtained the PSS signal strength values in the respective sample signal.
Comparison means 650 is determined maximum PSS signal strength signal intensity estimated values subsequently, and should maximum PSS signal strength signal intensity estimated value and predetermined first threshold compare.If should maximum PSS signal strength signal intensity estimated value greater than first threshold, the signal strength signal intensity of frequency band that the PSS signal place of this intensity estimated value maximum then is described can be accepted, therefore insert frequency band determine device 670 with the frequency band at the PSS signal place of this intensity estimated value maximum as the frequency band that will insert.If maximum PSS signal strength signal intensity estimated value is less than first threshold, then illustrate this intensity estimated value maximum PSS signal place frequency band signal strength signal intensity too a little less than, therefore frequency band switching device shifter 690 switches the frequency of the oscillator in the subscriber equipment, makes and obtain sample signal on other frequency band.Subsequently, re-execute the frequency band search procedure.
The inventor notices, after by the oscillator frequency in the switching subscriber equipment all frequency bands having been carried out said method, can determine the frequency band that subscriber equipment will insert by utilizing suitable first threshold usually.Yet under some extreme cases, the maximum PSS signal strength values that subscriber equipment is determined on all frequency bands may be all less than first threshold, then preferably second threshold value can be set this moment, if maximum PSS signal strength values is greater than second threshold value, then directly with the frequency band at maximum PSS signal strength values place as the frequency band that will insert, otherwise point out the user not have frequency band to insert.
By the frequency band searcher 600 that is proposed according to the abovementioned embodiments of the present invention, only considered advantageously that being used for frequency band from signal of base station inserts, and for example avoided interference noise influence to a great extent from other subscriber equipmenies.
The inventor notices, though can directly utilize correlation to judge as the signal strength signal intensity of PSS signal, owing to may have the uplink interference signal in the sample signal that receives, therefore may influence judged result.
Therefore according to a kind of improvement project of the present invention, can utilize normalized correlation to estimate the signal strength signal intensity of PSS signal, also can utilize peak-to-average force ratio M to estimate the signal strength signal intensity of PSS signal.About utilizing the content of normalization correlation and peak-to-average force ratio, specifically, repeat no more here referring to the description of method part.
By utilizing peak-to-average force ratio M to estimate the signal strength signal intensity of PSS signal, advantageously overcome the influence of uplink interference signal, and can further improve the accuracy of frequency band search.
The 5th embodiment
In order further to improve accuracy for the estimation of PSS signal, preferably, frequency band searcher 600 according to the present invention can also comprise and obtain number of times judgment means 660 that it can be so that frequency band searcher 600 be carried out repeatedly frequency band search procedure at each frequency band.
Fig. 7 shows the schematic diagram of improved frequency band searcher 700 according to an embodiment of the invention.
As can see from Figure 7, this frequency band searcher 600 also comprises on the basis of structure shown in Figure 6 and obtains number of times judgment means 660, it is configured to judge at the current search frequency band and whether obtains the number of times of all sample signals greater than predetermined the 3rd threshold value, if less than the 3rd threshold value, then control signal deriving means 610 is so that obtain sample signal rk from the current search frequency band once more, if greater than the 3rd threshold value then control frequency band switching device shifter 690 to switch search frequency band, so that on other frequency bands, detect.
After repeatedly carrying out the frequency band search procedure of same frequency band, can utilize average correlation, average normalized value or peak-to-average force ratio to determine the frequency band that will insert.This can be repeated no more here referring to according to the content in the described method of the 3rd embodiment.
Because each frequency band of method according to present embodiment has been carried out repeatedly, and judges the frequency band that will insert according to the result who repeatedly carries out, and has therefore further eliminated the influence of other Gaussian noises in the communication system, has improved the accuracy of judging.
Need to prove, in frequency band searcher 600 according to the present invention, can use the SSS signal equally.Because it is more more than PSS signal that the SSS signal has, so computing cost is bigger, yet its principle and above-described method are identical, and this is not described further.
Be not difficult to find out by above description,, provide following scheme according to embodiments of the invention:
1. 1 kinds of methods that are used for the frequency band search in the TDD-LTE system of remarks comprise:
The signal obtaining step: obtain on the search frequency band specific to signal of base station;
Intensity estimating step: estimate each intensity specific to signal of base station;
Comparison step: will compare specific to the intensity and the predetermined first threshold of signal of base station;
The frequency band determining step: when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert;
Frequency band switch step:, switch search frequency band, and re-execute above-mentioned steps at the frequency band after switching when intensity during less than predetermined first threshold.
Remarks 4. is according to each the described method in the above-mentioned remarks, wherein utilize store in the subscriber equipment specific to the copy of signal of base station with obtained estimate the intensity obtained specific to the correlation of signal of base station in time domain specific to signal of base station.
Remarks 5. is according to each the described method in the above-mentioned remarks, wherein utilize the normalization correlation to estimate the intensity of being obtained specific to signal of base station, described normalization correlation be with store in the subscriber equipment specific to the copy of signal of base station and after the correlation normalization of signal of base station in time domain, obtaining of being obtained.
Remarks 6. is according to each the described method in the above-mentioned remarks, wherein utilizes the peak-to-average force ratio of normalization correlation to estimate the intensity of being obtained specific to signal of base station.
7. 1 kinds of frequency band searchers (600) that are used for TDD-LTE system terminal/subscriber unit of remarks comprising:
Signal deriving means (610), its be arranged to obtain on the search frequency band specific to signal of base station;
Intensity estimation unit (630), it is arranged to estimates each intensity specific to signal of base station;
Comparison means (650), it is arranged to intensity and predetermined first threshold specific to signal of base station is compared;
Insert frequency band and determine device (670), it is arranged to when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert;
Frequency band switching device shifter (690), it is arranged to when intensity during less than predetermined first threshold, switches search frequency band.
Remarks 8. is master sync signal or subsynchronous signal specific to signal of base station wherein according to remarks 7 described frequency band searchers (600).
Remarks 9. is according to remarks 7 or 8 described frequency band searchers (600), also comprise and obtain number of times judgment means (660), its be arranged to judgement the current search frequency band obtain all specific to the number of times of signal of base station whether greater than predetermined the 3rd threshold value, if less than the 3rd threshold value, then carry out the signal obtaining step once more, so that obtain sample signal from the current search frequency band once more, if greater than the 3rd threshold value then control the frequency band switching device shifter and switch search frequency band.
Remarks 10. is according to each the described frequency band searcher (600) in the remarks 7 to 9, wherein intensity estimation unit (630) utilize store in the subscriber equipment specific to the copy of signal of base station with obtained estimate the intensity obtained specific to the correlation of signal of base station in time domain specific to signal of base station.
Remarks 11. is according to each the described frequency band searcher (600) in the remarks 7 to 9, wherein intensity estimation unit (630) utilizes the normalization correlation to estimate the intensity of being obtained specific to signal of base station, described normalization correlation be with store in the subscriber equipment specific to the copy of signal of base station and after the correlation normalization of signal of base station in time domain, obtaining of being obtained.
Remarks 12 is according to each the described frequency band searcher (600) in the remarks 7 to 9, and wherein intensity estimation unit (630) utilizes the peak-to-average force ratio of normalization correlation to estimate the intensity of being obtained specific to signal of base station.
Claims (9)
1. one kind is used for the method that frequency band is searched in the TDD-LTE system, comprising:
The signal obtaining step: obtain on the search frequency band specific to signal of base station;
Intensity estimating step: estimate each intensity specific to signal of base station;
Comparison step: will compare specific to the intensity and the predetermined first threshold of signal of base station;
The frequency band determining step: when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert;
Frequency band switch step:, switch search frequency band, and re-execute above-mentioned steps at the frequency band after switching when intensity during less than predetermined first threshold.
2. method according to claim 1 is master sync signal or subsynchronous signal specific to signal of base station wherein.
3. method according to claim 1 and 2, also comprise and obtain the number of times determining step: judge the current search frequency band obtain all specific to the number of times of signal of base station whether greater than predetermined the 3rd threshold value, if less than the 3rd threshold value, then carry out the signal obtaining step once more, so that obtain sample signal from the current search frequency band once more, if greater than the 3rd threshold value then carry out the frequency band switch step to switch search frequency band.
4. each the described method in requiring according to aforesaid right, wherein utilize store in the subscriber equipment specific to the copy of signal of base station with obtained estimate the intensity obtained specific to the correlation of signal of base station in time domain specific to signal of base station.
5. each the described method in requiring according to aforesaid right, wherein utilize the normalization correlation to estimate the intensity of being obtained specific to signal of base station, described normalization correlation be with store in the subscriber equipment specific to the copy of signal of base station and after the correlation normalization of signal of base station in time domain, obtaining of being obtained.
6. each the described method in requiring according to aforesaid right wherein utilizes the peak-to-average force ratio of normalization correlation to estimate the intensity of being obtained specific to signal of base station.
7. frequency band searcher (600) that is used for TDD-LTE system terminal/subscriber unit comprising:
Signal deriving means (610), its be arranged to obtain on the search frequency band specific to signal of base station;
Intensity estimation unit (630), it is arranged to estimates each intensity specific to signal of base station;
Comparison means (650), it is arranged to intensity and predetermined first threshold specific to signal of base station is compared;
Insert frequency band and determine device (670), it is arranged to when intensity during greater than predetermined first threshold, selection intensity greater than predetermined first threshold specific to the frequency band at signal of base station place as the frequency band that will insert;
Frequency band switching device shifter (690), it is arranged to when intensity during less than predetermined first threshold, switches search frequency band.
8. frequency band searcher according to claim 7 (600) is master sync signal or subsynchronous signal specific to signal of base station wherein.
9. according to claim 7 or 8 described frequency band searchers (600), also comprise and obtain number of times judgment means (660), its be arranged to judgement the current search frequency band obtain all specific to the number of times of signal of base station whether greater than predetermined the 3rd threshold value, if less than the 3rd threshold value, then carry out the signal obtaining step once more, so that obtain sample signal from the current search frequency band once more, if greater than the 3rd threshold value then control the frequency band switching device shifter and switch search frequency band.
10 according to each the described frequency band searcher (600) in the claim 7 to 9, and wherein intensity estimation unit (630) utilizes the peak-to-average force ratio of normalization correlation to estimate the intensity of being obtained specific to signal of base station.
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| CN103906181A (en) * | 2012-12-28 | 2014-07-02 | 上海摩波彼克半导体有限公司 | Frequency band scanning method and device and network selection method |
| CN105101353A (en) * | 2015-06-26 | 2015-11-25 | 华为技术有限公司 | Frequency band searching method and device |
| CN106792623A (en) * | 2016-12-05 | 2017-05-31 | 青岛海信移动通信技术股份有限公司 | Mobile terminal searches network access method and mobile terminal |
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| CN102572970A (en) * | 2011-12-21 | 2012-07-11 | 华为技术有限公司 | Method and device for searching cell in homogeneous-frequency neighboring cells |
| CN103428819A (en) * | 2012-05-24 | 2013-12-04 | 富士通株式会社 | Carrier frequency point searching method and device |
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| CN106792623A (en) * | 2016-12-05 | 2017-05-31 | 青岛海信移动通信技术股份有限公司 | Mobile terminal searches network access method and mobile terminal |
| CN106792623B (en) * | 2016-12-05 | 2021-05-28 | 青岛海信移动通信技术股份有限公司 | Network searching access method of mobile terminal and mobile terminal |
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