CN101399561B - Uplink access signal capturing method based on signal pre-processing technique - Google Patents

Uplink access signal capturing method based on signal pre-processing technique Download PDF

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CN101399561B
CN101399561B CN2007101525416A CN200710152541A CN101399561B CN 101399561 B CN101399561 B CN 101399561B CN 2007101525416 A CN2007101525416 A CN 2007101525416A CN 200710152541 A CN200710152541 A CN 200710152541A CN 101399561 B CN101399561 B CN 101399561B
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signal
access
zero clearing
carried out
processing
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CN101399561A (en
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丁美玲
段然
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ZTE Corp
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ZTE Corp
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Abstract

The invention discloses an up access signal acquisition method based on signal pretreatment technology. Aiming at the characteristic that disturbance suffered by an up access signal derives from regular disturbance and random disturbance, selectivity signal minimum clearing, selectivity signal saturation and two target-oriented methods are provided. A regular disturbance position is determined by shelving; and then a current up signal is cleared and the regular disturbance is removed. The up access signal which is cleared is evaluated by automatic gain control, and then is saturated by using regular derivation value to remove the random disturbance. The method improves acquisition performance of the up acquisition signal by reducing or even eliminating the influence of the disturbance on the up access signal, and finally improves access success rate and direct-cut operation success rate of the system.

Description

Up access signal acquisition methods based on the Signal Pretreatment technology
Technical field
The present invention relates to GSM, particularly up access signal capturing method in time-division duplex (TD-SCDMA) GSM.
Background technology
In GSM, it is mutual basis that the recipient obtains the timing information that receives signal.Generally speaking, at forward link direction, handheld device can be obtained timing information through pilot signal, and safeguards through monitored pilots signal or special signal; In reverse link direction, handheld device need be sent and inserted signal so that the system equipment side is obtained the timing information of reverse link signal, and system equipment is safeguarded timing information through the monitoring special signal subsequently.
At WCDMA (Wideband Code Division Multiple Access; The WCDMA access) in the system; Handheld device is sent prefix so that system equipment obtains timing information; And at TD-SCDMA (Time Division-Synchronous Code Division Multiple Access; The TD SDMA access) in the system, handheld device is then sent SYNC-UL (uplink synchronous code) so that system equipment obtains timing information through going up at UpPCH (Uplink pilotchannel, uplink synchronous channel).The patent No. is that 97118934.X's the Chinese patent of " foundation of synchronous code division multiple access communication chain and maintenance method " has proposed the special frames structure (as shown in Figure 1) in the TD-SCDMA system, and has set up the framework of uplink synchronous.The patent No. is that the Chinese patent of 03119174.6 " a kind of be used to detect the method that user terminal inserts at random " is that the basis has proposed the method that a kind of uplink synchronous is set up with the TD-SCDMA agreement then.
Because TDD (Time Division Duplexing; Time division duplex) GSM is the basis with the time division duplex; Be that down link has used identical frequency with up link, this just makes down link and up link have identical wireless propagation environment, in the TD-SCDMA of reality system; The DwPTS of this sub-district and adjacent sub-district (Downlink Piloting Time Slot; Descending pilot frequency time slot) will produce Gp (protection time slot) and UpPTS (Uplink Piloting Time Slot, uplink pilot time slot) time slot and disturb (as shown in Figure 2), about this interference level even can reach-80dBm; And the detection signal of uplink synchronous code itself only can reach under most of device situation-below the 100dBm, the signal to noise ratio of up like this access signal is difficult to reach requirement.One of main purpose that the UpPCH Shifting agreement of TD-SCDMA system proposes is exactly in order to address the above problem; To reduce interference level; But the capacity that needs sacrificial system, and strengthen the complexity of the network planning and optimization, and if directly to adopt the patent No. be the method that 03119174.6 Chinese patent provides; Then the detection probability of uplink synchronous code is very low, finally causes inserting success rate and the direct-cut operation success rate is low.
Therefore, the up access signal-detection probability that improves the GSM that comprises TD-SCDMA is with development that greatly promotes relevant system and maturation.For this reason, this patent has proposed zero clearing of selectivity signal and the saturated two kinds of methods of selectivity signal, improving the performance of obtaining of up access signal, and finally improves the access success rate and the direct-cut operation success rate of system.
Summary of the invention
Technical problem to be solved by this invention is; Up access signal is received the influence of fixing interference and random disturbances; A kind of up access signal acquisition methods based on the Signal Pretreatment technology is provided pointedly; Make in uplink synchronous and the up quasi synchronous TDD GSM system equipment accurately guides user equipment accomplish the process of setting up of uplink synchronous, fundamentally solve the low success rate problem that uplink synchronous is set up process.
The present invention provides a kind of up access signal acquisition methods based on the Signal Pretreatment technology, comprises the steps:
Filtering is carried out to the signal power of up each sampled point of access slot of obtaining in the base station, confirms fixing position of disturbing according to filtered envelope characteristic, the selectivity zero clearing is carried out in fixing position of disturbing in the current instantaneous signal handle; After signal after zero clearing handled carried out automatic gain control and adds a constant offset, the signal after zero clearing handled carried out the saturated processing of selectivity, carries out matched filter processing after the skew of rollback same fixed again and obtains up access signal.
Said method further is divided into following steps:
(1) obtains the power of each sampled point signal of up access slot;
(2) sampled point history and current signal power are carried out Filtering Processing, rule out fixing position of disturbing, utilize the fixedly signal zero clearing of interference position in current sampled signal of zero clearing thresholding according to filtered power envelope characteristic;
(3) upward signal after the signal zero clearing processing is carried out the estimation that automatic gain is controlled value; After the signal that obtains for automatic gain control adds the automatic gain control value of a constant offset; Again the upward signal after the zero clearing is carried out saturated processing; And, obtain pretreated up access signal with the automatic gain control value that the current sampled signal rollback same fixed after the saturated processing squints;
(4) up access signal and predetermined access code after the preliminary treatment are carried out matched filter processing, obtain up access for information about thereby find out the peaked position of matched filtering result.
In the said step (2),, confirm that the signaling point greater than signal zero clearing thresholding is the interference of fixed position through the estimation of power envelope being obtained signal zero clearing thresholding.
In the said step (2), in according to the fixing position step of disturbing of filtered power envelope characteristic judgement:
Preestablish the fixing positional number N that disturbs, the method through ordering with filtering after the position of maximum N the point of signal strength signal intensity, confirm as the position of fixing interference.
In the said step (2), utilizing the zero clearing thresholding fixedly during the signal zero clearing of interference position, is that the current demand signal of selecting the place, fixed position is changed to 0 in current sampled signal.
In the said step (3), the automatic gain control value of said constant offset is to adopt 2 M power.
When carrying out Filtering Processing in the said step (2), adopt the Alpha filter that sampled point signal history and current is carried out the power Filtering Processing.When carrying out Filtering Processing in the said step (2), adopt the method for change Alpha filter coefficient at initial several frames of filtering.
The present invention is directed to the characteristic of the suffered interference source of up access signal in fixing interference and random disturbances; The saturated two kinds of methods targetedly of zero clearing of selectivity signal and selectivity signal have been proposed; Confirm fixedly interference position through Filtering Processing earlier, current upward signal is carried out zero clearing handle, eliminate fixing the interference; Up access signal after zero clearing is handled utilizes fixed offset value that it is carried out saturated processing and eliminates random disturbances through automatic gain control valuation.Use the present invention, can reduce even eliminate the influence of disturbing the up access signal capture of system equipment, improved the acquisition performance of up access signal, and finally improved the access success rate and the direct-cut operation success rate of system.And the up access signal-detection probability of GSM that raising is comprised TD-SCDMA is with development that greatly promotes relevant system and maturation.
Description of drawings
Fig. 1 is the subframe structure sketch map of TD-SCDMA system;
Fig. 2 is the sketch map of the suffered interference of access slot in the TD-SCDMA system;
Fig. 3 is concise and to the point implementing procedure figure of the present invention;
Fig. 4 is a kind of flow chart of embodiment of the present invention;
Fig. 5 is the contrast sketch map before and after the zero clearing of selectivity signal;
Fig. 6 is the contrast sketch map of the saturated front and back of selectivity signal.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment technical scheme of the present invention is done further explain.
As far as with TDD being the system on basis; Down link has used identical frequency with up link; The descending time slot of adjacent sub-district all may have influence on the ascending time slot signal of this sub-district; And must send up access signal through ascending time slot before the subscriber equipment connecting system equipment, so that system equipment obtains subscriber equipment for information about.In the sketch map of the suffered interference of access slot as shown in Figure 2, possibly there is overlapping in the interference of descending time slot with ascending time slot, and descending DwPTS even TS0 (time slot 0) can disturb up GP, UpPTS because of time delay.
Because the continuity of network, these interference signals possess the certain distribution characteristics and the relative stability of envelope, therefore, through filtering technique, can obtain the distribution of these interference signals, and can remove through certain means; And, then can its influence to up access signal capture be reduced to bottom line through saturated processing for the unsettled interference signal of envelope.
The present invention has proposed the saturated two kinds of methods of zero clearing of selectivity signal and selectivity signal in order to remove above-mentioned interference, and uses in the up access signal capture process of these two technology system equipment in the TDD GSM.
The present invention has utilized the steady characteristic of power of up access signal self in the GSM; Adopt the zero clearing of selectivity signal to remove long-term power high reject signal stably; And adopting the saturated processing of selectivity signal to remove the high reject signal of short-term, the above-mentioned two kinds of methods that can independently implement combine use interference signal are reduced to bottom line for the influence of up access.
The up access signal acquisition methods that the present invention proposes based on the Signal Pretreatment technology, as shown in Figure 3, comprise the steps:
Step 301 is obtained the power of each sampled point signal of up access slot;
Step 302 is carried out Filtering Processing to historical and current sampled point signal power, to obtain filtered power envelope;
Step 303 rules out fixing position of disturbing according to the envelope characteristic of filtering, and definite follow-up signal handle in the signal area of zero clearing;
, can obtain fixedly during interference position in judgement, also can obtain according to the current sampling filter power of sampled point according to the history samples filtered power of sampled point.During judgement, need to set a constant power thresholding, for filtered history samples filtered power and/or current sampling filter power, if the power of a certain position is higher than the constant power thresholding in the power envelope, then this position of decidable is fixing position of disturbing.
Step 304, the fixedly signal zero clearing of interference position in current sampled signal is about to select the current demand signal of locating the fixed position and is changed to 0;
Step 305, the residual signal that utilizes step 304 to obtain are carried out the estimation of automatic gain control (AGC) value;
Step 306, the AGC value of utilizing step 305 to obtain adds a constant offset AGC value, and the sampled signal that obtains after the zero clearing in the step 304 is carried out AGC and saturated processing;
Step 307, the influence of the signal rollback constant offset AGC value that step 306 is obtained, thus the subsequent treatment signal is concentrated on the level zone of presetting, consider the particularity of Digital Signal Processing, the AGC value of this constant offset can adopt 2 M power;
Step 308, the signal and the predetermined access code that adopt step 307 to extract carry out matched filter processing, obtain up access for information about thereby find out the peaked position of matched filtering result.
As shown in Figure 4, shown an application example of the present invention, specifically may further comprise the steps:
Step 401, system equipment are obtained the reception signal, if capture region is made up of many antennas, then need obtain the reception signal of many antennas.
Step 402 for each zone of asking up access signal capture separately, is obtained I, the Q quadratic sum of each sampled point signal of uplink synchronous zone, if capture region is made up of many antennas, then can these antenna corresponding sampling points be carried out the power stack.
Step 403 utilizes filter that the sampled point signal of history is carried out the power Filtering Processing.Utilize the energy of filter channel impulse response to received signal to carry out filtering, suppose that the output sequence of last filter is:
Z 1(n-1)，Z 2(n-1)，Z 3(n-1)，...，Z i(n-1)，...，Z I(n-1)
Wherein I is the length of filter output sequence, is generally the size of up access signal capture window; N is the sequence number of the n time filtering, and for the 1st filtering, the output of filter can directly be set to value relevant with the received signal power sequence even received signal power sequence itself.The received signal power sequence of definition input is X (n), then under the situation that adopts the Alpha filter, has:
Z i(n)＝β*Z i(n-1)+(1-β)*X i(n) i＝1，2，…，I
Wherein β is the coefficient of Alpha filter, but interval is [0,1], can also adopt the method that becomes the Alpha filter coefficient at initial several frames of filtering, to improve convergence.
The above-mentioned filtering method that is used for Filtering Processing also has a lot, has only enumerated an example commonly used here, can also adopt like recurrence and on average wait filtering method.
Step 404, the position that obtains maximum N the point of signal strength signal intensity after the filtering can obtain through the method for ordering, and wherein N is a configuration parameter, is 40 as disposing N; Also can be through the estimation of power envelope being obtained signal zero clearing thresholding, for noting, as shown in Figure 5 greater than the signaling point of signal zero clearing thresholding.
Step 405 will be passed through some received signal zero clearing in the current frame signal sequence that step 404 is selected, and the effect after its zero clearing is as shown in Figure 5.
Step 406 is utilized remaining signal to carry out automatic gain control and is estimated.
Step 407 based on the gain value, is carried out automatic gain to received signal and is handled.
Step 408 is to the move to left saturated processing of M position of upward signal.
Step 409, with the M position that moves to right of the residue sampled signal after the saturated processing, integrating step 408, its effect is as shown in Figure 6.
Step 410, matched filter processing obtain up access for information about.
In step 408,409, being in the consideration of simplification, can be exactly move to left the M position and the M position that moves to right in Digital Signal Processing with constant offset AGC value people for being set to multiply by 2^M side like this.
The preferred embodiments of the present invention that are merely described herein are not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Therefore, all any modifications of within spirit of the present invention and principle, being done, be equal to replacement, improve and upgrade or the like, all should be included within protection scope of the present invention.

Claims (8)

1. the up access signal acquisition methods based on the Signal Pretreatment technology is characterized in that, comprises the steps:
Filtering is carried out to the signal power of up each sampled point of access slot of obtaining in the base station, confirms fixing position of disturbing according to filtered envelope characteristic, the selectivity zero clearing is carried out in fixing position of disturbing in the current instantaneous signal handle; After signal after zero clearing handled carried out automatic gain control and adds a constant offset, the signal after zero clearing handled carried out the saturated processing of selectivity, carries out matched filter processing after the skew of rollback same fixed again and obtains up access signal.
2. up access signal acquisition methods as claimed in claim 1 is characterized in that said method further is divided into following steps:
(1) obtains the power of each sampled point signal of up access slot;
(2) sampled point history and current signal power are carried out Filtering Processing, rule out fixing position of disturbing, utilize the fixedly signal zero clearing of interference position in current sampled signal of zero clearing thresholding according to filtered power envelope characteristic;
(3) upward signal after the signal zero clearing processing is carried out the estimation that automatic gain is controlled value; After the signal that obtains for automatic gain control adds the automatic gain control value of a constant offset; Again the upward signal after the zero clearing is carried out saturated processing; And, obtain pretreated up access signal with the automatic gain control value that the current sampled signal rollback same fixed after the saturated processing squints;
(4) up access signal and predetermined access code after the preliminary treatment are carried out matched filter processing, obtain up access for information about thereby find out the peaked position of matched filtering result, said is original position for information about.
3. up access signal acquisition methods as claimed in claim 2 is characterized in that, in the said step (2), through the estimation of power envelope being obtained signal zero clearing thresholding, confirms that the signaling point greater than signal zero clearing thresholding is the interference of fixed position.
4. up access signal acquisition methods as claimed in claim 2 is characterized in that, in the said step (2), in according to the fixing position step of disturbing of filtered power envelope characteristic judgement:
Preestablish the fixing positional number N that disturbs, the method through ordering with filtering after the position of maximum N the point of signal strength signal intensity, confirm as the position of fixing interference.
5. up access signal acquisition methods as claimed in claim 2 is characterized in that, in the said step (2), utilizing the zero clearing thresholding fixedly during the signal zero clearing of interference position, is that the current demand signal of selecting the place, fixed position is changed to 0 in current sampled signal.
6. up access signal acquisition methods as claimed in claim 2 is characterized in that, in the said step (3), the automatic gain control value of said constant offset is to adopt 2 M power, and wherein M is an integer.
7. up access signal acquisition methods as claimed in claim 2 is characterized in that, when carrying out Filtering Processing in the said step (2), adopts the Alpha filter that sampled point signal history and current is carried out the power Filtering Processing.
8. up access signal acquisition methods as claimed in claim 7 is characterized in that, when carrying out Filtering Processing in the said step (2), adopts the method for change Alpha filter coefficient at initial several frames of filtering.
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CN101577987B (en) * 2009-06-12 2012-02-15 华为技术有限公司 Speech frame processing method, base station transceiver station, base station controller and system
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6351504B1 (en) * 1997-12-26 2002-02-26 Alps Electric Co., Ltd. Reception circuit
CN1716817A (en) * 2004-06-30 2006-01-04 西门子（中国）有限公司 Method for realizing user's equipment downward synchronization in TD-SCDMA mobile communication system
CN1859039A (en) * 2006-02-08 2006-11-08 华为技术有限公司 Mobile communication system and its method for reducing up channel Doppler effect

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6351504B1 (en) * 1997-12-26 2002-02-26 Alps Electric Co., Ltd. Reception circuit
CN1716817A (en) * 2004-06-30 2006-01-04 西门子（中国）有限公司 Method for realizing user's equipment downward synchronization in TD-SCDMA mobile communication system
CN1859039A (en) * 2006-02-08 2006-11-08 华为技术有限公司 Mobile communication system and its method for reducing up channel Doppler effect

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