CN100518047C - A signal capturing method for resisting high-delay extension channel - Google Patents
A signal capturing method for resisting high-delay extension channel Download PDFInfo
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- CN100518047C CN100518047C CNB2007103041145A CN200710304114A CN100518047C CN 100518047 C CN100518047 C CN 100518047C CN B2007103041145 A CNB2007103041145 A CN B2007103041145A CN 200710304114 A CN200710304114 A CN 200710304114A CN 100518047 C CN100518047 C CN 100518047C
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Abstract
The invention discloses a signal capture method that can resist big time delay spreading signal channel. After the self-correlated operation on the signal, a first time point is searched where the self-correlated output extent value is greater than an extent threshold Tamp in the self-correlated extent waveform; and then, a time slice with certain length like T2/2 is delayed from the first time point to decide a second time point where the self-correlated output extent value is less than the threshold value Tamp. after the second time point, the time slice that is less than and equal to a signal period T2 is searched until a wave crest is found that has an greater extent value than the threshold value Tamp, and the waveform width of the wave crest, which is above the threshold value Tamp, should be greater than a width threshold value Twid. And then the corresponding time point of the wave crest is the coarse synchronizing position. The signal capture method of the invention can resist big time delay spreading signal channel, and improves the efficiency of signal capture in real time.
Description
Technical field
The present invention relates to the synchronous reception technique of communication technical field, relate in particular to a kind of signal acquisition methods of resisting high-delay extension channel.
Background technology
So-called signal capture is exactly the initial synchronization that finger is received system signal.Receiving system only after obtaining initial synchronisation, is carried out fine synchronization again, and is constantly followed the tracks of synchronously in the process of received signal, can guarantee that just receiving system obtains real signal Synchronization.Therefore the initial synchronisation of picked up signal is first treatment step of receiver synchro system, also is crucial treatment step.The purpose of signal capture is to obtain rough signal Synchronization position, but not definite signal Synchronization position.And because the diversity of wireless channel, certain signal acquisition methods is difficult to guarantee can both obtain definite signal Synchronization position under all channel circumstances; In other words, at some channel situation, this algorithm can obtain definite signal Synchronization position, but for other channel situation, this algorithm even have the possibility that lost efficacy.Therefore, a most important characteristics of signal capture algorithm is to have versatility, promptly can be in office under what channel situation, obtain the coarse synchronization position of receiving system.Further, after the acquisition coarse synchronization, utilize fine synchronization again, just can obtain more definite signal Synchronization position.
DVB (Digital Video Broadcasting, the digital video broadcasting) system in Europe has adopted multi-carrier OFDM (Orthogonal Frequency Division Multiplexing, OFDM) Channel Transmission technology.The signal acquisition methods of DVB system has been utilized Cyclic Prefix (CP, the Cyclic Prefix) part of OFDM symbol.Because the CP partial-length is shorter, only is 7 microseconds as the shortest CP length under the 2K pattern in the DVB system, therefore can't guarantee the robustness of signal capture algorithm; And because CP part can't accurately identify the original position of each signal frame, even therefore can obtain the original position of certain OFDM symbol, receiving system also can't be fast and is searched out the original position of each signal frame definitely.
Synchronous predicament for fear of the DVB systems face, CMMB (the China MobileMultimedia Broadcasting of China, China Mobile multimedia broadcasting) system has proposed a kind of new frame structure, section start at each time slot is provided with a beacon, thereby guaranteed that receiver can not utilize the CP of OFDM symbol partly to carry out synchronously, only utilized the sync bit that beacon part just can picked up signal.
As shown in Figure 1, provided the frame structure schematic diagram of CMMB system physical layer.In the frame structure of CMMB system physical layer, be divided into 40 time slots with 1 second, each time slot is made up of 1 beacon and 53 OFDM symbols.
As shown in Figure 2, provided the composition structural representation of beacon in each time slot of frame structure of CMMB system physical layer.In each time slot, each beacon is made up of a TxID (sender unit identification sequence) and two same synchronizing signals (SYNC, Synchronous signal).The time span of each synchronizing signal is 204.8 microseconds, is far longer than the CP length (51.2 microsecond) of OFDM symbol.
At the system with similar above-mentioned CMMB frame structure, signal acquisition methods commonly used all is to utilize two same synchronous (SYNC) signals to handle, and concrete steps are: at first, input signal is carried out autocorrelation operation; Then, the maximum of searching auto-correlation output valve amplitude is come the coarse synchronization position of picked up signal.As shown in Figure 3, described the oscillogram of the auto-correlation output valve amplitude of traditional signal acquisition methods acquisition, wherein, time T is much smaller than time T 2.For example in the CMMB system, T2 is corresponding to the length of a time slot.The characteristics of this waveform shown in Figure 3 are that a crest only appears in each time slot (T2).
But from another perspective, SYNC is the oversize transmission capacity that will influence system of synchronizing signal.Therefore, in the more responsive system of transmission capacity,, will have to consider that the length with the SYNC signal reduces in order to improve the transmission capacity of system; And theoretically, the time delay expansion of wireless channel necessarily might be greater than the length of SYNC signal.When the time delay expansion of wireless channel during greater than the length of synchronizing signal, the waveform of auto-correlation output valve amplitude a plurality of crests (as shown in Figure 4) will occur at each T2 in (as the time slot) time, thereby will have caused traditional signal acquisition methods with no longer valid.
In sum, because present signal acquisition methods is not considered the situation of high-delay extension channel, thereby need a kind of signal acquisition methods of resisting high-delay extension channel.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of signal acquisition methods of resisting high-delay extension channel, at the situation of high-delay extension channel, realizes signal capture fast and accurately, promptly determines thick sync bit in synchronizing process fast and accurately.
The technical solution used in the present invention is:
The invention provides a kind of signal acquisition methods, be used for, catch the sync bit that has the signal of two same synchronizing signals in each beacon of each time slot, comprise the steps: in the signal Synchronization process
The thresholding T of A, configuration settings auto-correlation output amplitude
AmpAnd the width threshold T of auto-correlation output amplitude waveform
Wid
B, described signal is carried out auto-correlation computation, search and determine that an auto-correlation output amplitude value is greater than thresholding T
AmpVery first time point;
C, after postponing very first time section backward, very first time point determines that auto-correlation output amplitude value is less than thresholding T
AmpSecond time point;
D, be less than or equal to signal period T since second time point
2Second time period in search backward, until finding a crest, if the range value of this crest is greater than thresholding T
AmpAnd the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width greater than width threshold T
Wid, determine that then this crest time corresponding point is the coarse synchronization position of signal.
Further, described method further comprises:
E, if do not search the range value of this crest greater than thresholding T
AmpAnd the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width greater than width threshold T
WidCrest, then return step B and carry out the signal capture process again.
Described method further comprises:
E1, if do not search the range value of this crest greater than thresholding T
AmpAnd the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width greater than width threshold T
WidCrest, then return steps A and carry out the signal capture process again.
Described method further comprises:
When carrying out the signal capture process again, in described step B, will search for the amplitude of acquisition last time greater than thresholding T
AmpThe crest time point carry out first time point in the signal capture process again as this.
Very first time section among the described step C is half of signal period.In the steps A, the thresholding T of described auto-correlation output amplitude
AmpBe to set according to the average power of signal, the width threshold T of described auto-correlation output amplitude waveform
WidThe time-delay that is multipath is set.
Because present signal acquisition methods is not considered the situation of high-delay extension channel, Comparatively speaking, signal acquisition methods of the present invention, at the characteristics of the signal of high-delay extension channel,, utilize the peak value Rule of judgment from the signal of having expanded, to find a qualified crest fast and accurately by determining to comprise the search cycle of a signal, thereby navigate to thick sync bit, thereby, can improve the efficient that signal Synchronization is caught to the channel circumstance of Chinese People's Anti-Japanese Military and Political College's time delay expansion.
Description of drawings
Fig. 1 is the frame structure schematic diagram of CMMB system physical layer in the background technology of the present invention;
Fig. 2 is the composition structural representation of beacon in each time slot of frame structure shown in Figure 1;
Fig. 3 is the oscillogram of the auto-correlation output valve amplitude that obtains of traditional signal acquisition methods;
Fig. 4 is when the time delay expansion of wireless channel during greater than the length of synchronizing signal, the oscillogram of auto-correlation output valve amplitude;
Fig. 5 is the signal acquisition methods flow chart of antagonism high-delay extension channel in the embodiment of the invention.
Embodiment
Below in conjunction with drawings and Examples technical scheme of the present invention is described in detail.
The present invention is directed to present signal acquisition methods and do not consider the situation of high-delay extension channel, proposed a kind of signal acquisition methods of resisting high-delay extension channel.More exactly, the signal acquisition methods that the present invention proposes can be handled the waveform of auto-correlation output valve amplitude as shown in Figure 4, and wherein, time T is much smaller than time T
2, and at each T
2To occur in (as the time slot) time interval a plurality of crests (in Fig. 4, exemplarily only provided two crests, but not as the limit).
The signal acquisition methods that the present invention proposes, as shown in Figure 5, form by following treatment step:
The 1st step:, set the thresholding T of auto-correlation output amplitude according to system parameters
Amp, the width threshold T of setting auto-correlation output amplitude waveform
Wid
For receiving system, usually all have automatic gain control AGC equipment or processing mode, and automatic gain control AGC directly influences the setting of threshold value, but the AGC of different system might be different again, thereby, for the thresholding T of described auto-correlation output amplitude
AmpWidth threshold T with auto-correlation output amplitude waveform
Wid, when implementing, can carry out adaptive settings according to systematic function requirement and power rating.
When the threshold settings of real system, generally set according to simulation result, such as, according to the output waveform of emulation, set a threshold value, move simulated program then, see whether this threshold value is effective, if invalid, revise the respective doors limit value again.Usually, the amplitude threshold value is relevant with the average power of signal, and average power is big more, and the amplitude threshold value is just big more, and threshold value is just more little more by a small margin; And waveform width threshold value is relevant with the time delay expansion of multipath, and time delay expansion is big more, and waveform width threshold value is just big more, and small form width threshold value is just more little more.
The 2nd step: described signal is carried out auto-correlation computation, in the auto-correlation amplitude wave-shape, search a time point, be designated as first time point, the auto-correlation output amplitude value of this time point correspondence is greater than thresholding T
Amp
The 3rd step: the time period such as the T that postpone certain length from first time point backward
2/ 2, guarantee to postpone the corresponding auto-correlation output amplitude value of back time corresponding point (being designated as second time point) less than thresholding T
AmpThen, search for backward from second time point that (search length is less than or equal to T
2), until finding a crest, its range value should be greater than thresholding T
Amp, and the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width should be greater than width threshold T
Wid
If above-mentioned condition satisfies, promptly finished the signal capture process, this crest time corresponding point is exactly the coarse synchronization position of signal.
If above-mentioned condition does not satisfy, then forward the 1st step Reparametrization T to
AmpAnd T
WidAfter, carry out the signal capture process again; Perhaps directly returned for the 2nd step, keep parameter T
AmpAnd T
WidConstant, carry out the signal capture process more again.Wherein, a kind of easy method can be greater than thresholding T with this amplitude of searching for acquisition
AmpThe crest time point as first time point in the signal capture process next time.That is to say, for the non-process of search first, then can be with the crest time point of last time search as the very first time point in this signal capture process.
Because present signal acquisition methods is not considered the situation of high-delay extension channel, Comparatively speaking, signal acquisition methods of the present invention, at the characteristics of the signal of high-delay extension channel, by determining to comprise at least the search cycle of a signal, utilize the peak value Rule of judgment from the signal of having expanded, to find a qualified crest fast and accurately, thereby navigate to thick sync bit, thereby, can improve the efficient that signal Synchronization is caught to the channel circumstance of Chinese People's Anti-Japanese Military and Political College's time delay expansion.
Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.
Claims (7)
1, a kind of signal acquisition methods is used in the signal Synchronization process, catches the sync bit that has the signal of two same synchronizing signals in each beacon of each time slot, it is characterized in that, comprises the steps:
The thresholding T of A, configuration settings auto-correlation output amplitude
AmpAnd the width threshold T of auto-correlation output amplitude waveform
Wid
B, described signal is carried out auto-correlation computation, search and determine that an auto-correlation output amplitude value is greater than thresholding T
AmpVery first time point;
C, after postponing very first time section backward, very first time point determines that auto-correlation output amplitude value is less than thresholding T
AmpSecond time point;
D, be less than or equal to signal period T since second time point
2Second time period in search backward, until finding a crest, if the range value of this crest is greater than thresholding T
AmpAnd the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width greater than width threshold T
Wid, determine that then this crest time corresponding point is the coarse synchronization position of signal.
2, signal acquisition methods as claimed in claim 1 is characterized in that, described method further comprises:
E, if do not search the range value of this crest greater than thresholding T
AmpAnd the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width greater than width threshold T
WidCrest, then return step B and carry out the signal capture process again.
3, signal acquisition methods as claimed in claim 1 is characterized in that, described method further comprises:
E1, if do not search the range value of this crest greater than thresholding T
AmpAnd the amplitude wave-shape at this crest place is at thresholding T
AmpOn the waveform width greater than width threshold T
WidCrest, then return steps A and carry out the signal capture process again.
4, signal acquisition methods as claimed in claim 2 is characterized in that, described method further comprises:
When carrying out the signal capture process again, in described step B, will search for the amplitude of acquisition last time greater than thresholding T
AmpThe crest time point carry out first time point in the signal capture process again as this.
5, signal acquisition methods as claimed in claim 1 is characterized in that, the very first time section among the described step C is half of signal period.
6, signal acquisition methods as claimed in claim 1 is characterized in that,
In the steps A, the thresholding T of described auto-correlation output amplitude
AmpBe to set according to the average power of signal.
7, signal acquisition methods as claimed in claim 1 is characterized in that,
In the steps A, the width threshold T of described auto-correlation output amplitude waveform
WidThe time-delay that is multipath is set.
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| CNB2007103041145A CN100518047C (en) | 2007-12-25 | 2007-12-25 | A signal capturing method for resisting high-delay extension channel |
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| CN114337726B (en) * | 2021-12-30 | 2024-08-30 | 青岛上合航天科技有限公司 | Acquisition method, apparatus and computer readable storage medium for spread spectrum reception |
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Denomination of invention: A signal capturing method for resisting high-delay extension channel Effective date of registration: 20130205 Granted publication date: 20090722 Pledgee: China Development Bank Co Pledgor: Beijing InnoFidei Technology Co. Ltd.|Beijing smartwell xunlian Polytron Technologies Inc|Anhui smartwell Communication Technology Co. Ltd. Registration number: 2013990000087 |
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Date of cancellation: 20140416 Granted publication date: 20090722 Pledgee: China Development Bank Co Pledgor: Beijing InnoFidei Technology Co. Ltd.|Beijing smartwell xunlian Polytron Technologies Inc|Anhui smartwell Communication Technology Co. Ltd. Registration number: 2013990000087 |
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Effective date of registration: 20151016 Address after: 100080, Beijing, Zhongguancun Haidian District Street 11, 100 million world wealth center, block A, 12 Patentee after: BEIJING BOXIN SHITONG TECHNOLOGY CO., LTD. Address before: 100084, room 23, floor 2303, building A, science and technology building, Qinghua science park, Beijing, Haidian District Patentee before: Beijing Chuangyi Vision Technology Co., Ltd. |
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