CN102223737B - Self-excitation interference elimination method of global system for mobile communication (GSM) repeater based on time slot detection - Google Patents

Self-excitation interference elimination method of global system for mobile communication (GSM) repeater based on time slot detection Download PDF

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CN102223737B
CN102223737B CN 201110155140 CN201110155140A CN102223737B CN 102223737 B CN102223737 B CN 102223737B CN 201110155140 CN201110155140 CN 201110155140 CN 201110155140 A CN201110155140 A CN 201110155140A CN 102223737 B CN102223737 B CN 102223737B
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CN102223737A (en
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王卫明
刘永飘
祁中洋
蔡清
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CICT Mobile Communication Technology Co Ltd
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Abstract

The invention discloses a self-excitation interference elimination method of a global system for mobile communication (GSM) repeater based on time slot detection, comprising the following steps: step one: carrying out time slot detection on a GSM signal entering a self-excitation elimination algorithm, and judging the effective time slot data to be used for the interference self-excitation elimination algorithm; step two: carrying out a normalization least mean square algorithm, and iterating and calculating a weight coefficient; and step three: updating the coefficient in a self-adapting filter by utilizing the iterative weight coefficient, and carrying out self-excitation interference elimination. The method provided by the invention has the advantages of adapting to the technical characteristics of GSM/EDGE (enhanced data rate for GSM evolution) signals, obtaining 30dB gain on antenna insulation degree of the repeater through carrying out interference self-excitation elimination algorithm processing on the valid data extracted in a time slot format, and reaching the requirements of the system on the GSM phase error and EDGE vector amplitude error when the signal is analyzed.

Description

GSM straight-forward station self-excitation interference elimination method based on the time slot detection
Technical field
The present invention relates to a kind of GSM straight-forward station self-excitation interference elimination method that detects based on time slot, be specifically related to a kind of self-excitation of in detecting the GSM/EDGE time slot format, carrying out normalization LMS algorithm under the prerequisite of effective information and disturb and eliminate method for designing.
Background technology
Wireless discharging-directly station uses scale day by day as the technology that strengthens the wireless network covering, but the difficulty of its system's construction is restricting its development always.Arrange badly if donor antenna and retransmitting antenna are isolated, very easily cause self-excitation, worsen the network coverage.
The wireless discharging-directly station of traditional approach overcomes self-excitation phenomena and mainly contains two kinds of methods, and the one, the isolation of increase alms giver and retransmitting antenna, the 2nd, the gain of attenuating repeater.When requiring the repeater coverage big, just can only avoid self-excitation by increasing isolation between antennae, generally require the isolation of this two slave antenna to gain more than the big 15dB than complete machine.Reach such gain margin GM (isolating-gain) can by improve dual-mode antenna frame rise from adopt modes such as corner reflector antenna, backfire antenna, yet this application scenario and construction are limited to some extent, and significantly increase the engineering construction cost.
Gsm system adopts time division multiple access (TDMA) technology, and except having this technical characterictic of time division multiplexing, another crucial technical characterictic is the burst sequence transmission.The emission of mobile station signal power is discontinuous, only launch pulse sequence in the time slot of regulation.In this time interval, the amplitude of modulated carrier frequency data flow rises to its nominal value from 0 value of beginning, stablizes a period of time at nominal value, and the phase place of signal obtained modulation and sent one group of bit this moment, and amplitude drops to 0 more then.Strengthen data transfer rate evolution system (EDGE) though introduced many level modulation mode (8PSK) as GSM, all control channels still adopt the GMSK modulation mode of GSM, and have the characteristic of burst sequence transmission.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of self-excitation interference elimination method that adapts to the gsm system transmission characteristic, to solve the gsm wireless repeater to the problem of insulated degree requirement.
The present invention addresses the above problem by the following technical programs, may further comprise the steps:
Step 1, the digital baseband signal d (n) and the prediction signal through sef-adapting filter output that are mixed with interference signal
Figure BDA0000067423850000021
Subtract each other and obtain e (n), namely Judge the time slot feature of e (n), the valid data in the storage time slots use for back level algorithm; Wherein, digital baseband signal d (n) is signal x (n) and noise N (n) sum, i.e. d (n)=x (n)+N (n);
Step 2, the normalized LMS algorithm of employing,
Figure BDA0000067423850000023
W in the formula i(n) the iteration coefficient for calculating, w I+1(n) be the weight coefficient after the iteration renewal, u is convergence factor, e v(n) be valid data after e (n) time slot detects,
Figure BDA0000067423850000024
Be e v(n) one section vector value, N is stored valid data length;
Step 3, the weight coefficient w after iteration upgraded I+1(n) as the coefficient input of sef-adapting filter, after complex coefficient filtering, produce the iteration estimated value of noise N (n)
Figure BDA0000067423850000025
Carry out self-excitation and disturb elimination.
Preferably, the time slot of above-mentioned steps one detects the following method of using:
Step S10, ask for e (n) signal mode square, i.e. performance number P E (n)
Step S11, according to the big or small setting power threshold value thresholding P of input full power signal Thre, compare P in real time E (n)With P ThreSize, when in a time slot, being consecutively detected length more than or equal to n1 and smaller or equal to the P that satisfies of n3 E (n)＜P ThreE (n) value that requires, and be consecutively detected length afterwards more than or equal to the P that satisfies of n2 E (n)〉=P ThreWhen the e (n) that requires is worth, enter step S12; Be the P that satisfies of n3 when in a time slot, being consecutively detected above length E (n)＜P ThreWhen the e (n) that requires is worth, enter step S13; When in a time slot duration, not satisfying above-mentioned two kinds of situations, enter step S14; If being consecutively detected above length in each time slot in continuous 8 time slots is the P that satisfies of n3 E (n)＜P ThreWhen the e (n) that requires is worth, enter step S15;
Step S12, constantly play at interval a n4 and begin peek constantly the time satisfying condition, get the e that length is n5 (n) value, be the valid data e in the time slot v(n) one section sequence enters step S16;
Step S13, can judge and learn that this time slot is empty slot, wait for next frame arrival constantly, not update coefficients w i(n), when counting down to a slot length and deduct the n3 value, enter step S10;
Step S14, can't judge that this time slot is empty slot or normal time slot, because system feedback disturbs stack can't judge valid data in the time slot, in order to make algorithmic statement as early as possible, the length of getting after this time slot finishes is e (n) value of n5, enters step S16;
Step S15, can judge and learn that this basic frame is empty frame that i.e. free of data transmission disturbs self-excitation to eliminate in order to be made an uproar in the end of repeater, the length of getting behind this basic frame end is e (n) value of n5, enters step S16;
Step S16, carry out normalization LMS algorithm, calculate iteration coefficient w i(n), enter step S10 cycle detection.
Preferably, the value of the n1 in the above-mentioned steps, n2, n3, n4 and n5 is determined by the position of valid data in structure of time slot in the gsm system structure of time slot.
Preferably, in above-mentioned steps two iterative formulas Be one section valid data in the GSM/EDGE time slot format, its vector length is the exponent number of sef-adapting filter.
Preferably, said method is applicable to the interference self-excitation elimination system of other time-division communication standard.
The advantage that the present invention is based on the GSM straight-forward station self-excitation interference elimination method of time slot detection is: adapt to the gsm system technical characteristic, valid data in the detection GSM time slot carry out the coefficient update of adaptive-filtering, and system's solution timing can satisfy the vector amplitude error scope of GMSK modulation accuracy and 8PSK modulation.The combined digital signal treatment technology has reduced the requirement of gsm wireless repeater project installation to isolation significantly.Test shows, method for designing of the present invention can make the gsm wireless antenna isolating level of direct amplifying station with antenna obtain the gain of 30dB, and satisfy phase error and vector amplitude error indication range.
Description of drawings
Fig. 1 eliminates theory diagram for disturbing self-excitation;
The time slot testing process figure of Fig. 2 for using in a kind of GSM straight-forward station self-excitation interference elimination method based on the time slot detection of the present invention.
Embodiment
Understand and enforcement the present invention for the ease of those of ordinary skills, the present invention is described in further detail below in conjunction with the drawings and the specific embodiments.
The present invention is based on the GSM straight-forward station self-excitation interference elimination method that time slot detects is characterised in that: enter input signal in the normalization LMS algorithm and be the valid data in the GSM/EDGE structure of time slot, carry out normalized LMS algorithm.
Seeing also Fig. 1, is to disturb self-excitation to eliminate theory diagram.From the digital baseband signal d (n) of Digital Down Convert, be signal and noise sum, i.e. d (n)=x (n)+N (n).The input of sef-adapting filter is the sampling of output signal, can be expressed as another noise N ' relevant with N (n) (n).When x (n) is uncorrelated with N (n), the coefficient w that sef-adapting filter will go out by normalization LMS iterative computation i(n) upgrade the filter coefficient input, to try hard to make the output of filter Best estimate for N (n)
Figure BDA0000067423850000052
E (n) is approximation signal x (n) like this, and its mean-square value E[e 2(n)] be minimum.Noise N (n) has just obtained counteracting to a certain degree.Normalization LMS iterative computation is input as the valid data of e (n) after the time slot feature detection, i.e. e v(n).
Seeing also Fig. 2, is the frame testing process figure that uses in a kind of GSM straight-forward station self-excitation interference elimination method based on the time slot detection of the present invention, namely detects e from e (n) v(n) process.This invention can further be specially:
Step 1: ask for e (n) signal mode square, i.e. performance number P E (n)
Step 2: according to the big or small setting power threshold value thresholding P of input full power signal Thre, compare P in real time E (n)With P ThreSize.When in a time slot, being consecutively detected length more than or equal to n1 and smaller or equal to the P that satisfies of n3 E (n)＜P ThreE (n) value that requires, and be consecutively detected length afterwards more than or equal to the P that satisfies of n2 E (n)〉=P ThreWhen the e (n) that requires is worth, enter step 3; Be the P that satisfies of n3 when in a time slot, being consecutively detected above length E (n)＜P ThreWhen the e (n) that requires is worth, enter step 4; When in a time slot duration, not satisfying above-mentioned two kinds of situations, enter step 5; If being consecutively detected above length in each time slot in continuous 8 time slots is the P that satisfies of n3 E (n)＜P ThreWhen the e (n) that requires is worth, enter step 6;
Step 3: the moment that satisfies condition plays an interval n4 and begins peek during the moment, gets the e that length is n5 (n) value, is the valid data e in the time slot v(n) one section sequence.Enter step 7.
Step 4: can judge that this time slot is empty slot.Wait for next frame arrival constantly, not update coefficients w i(n).When counting down to a slot length and deducting the n3 value, enter step 1.
Step 5: can't judge that this time slot is empty slot or normal time slot, because system feedback interference stack can't have been judged the valid data in the time slot.In order to make algorithmic statement as early as possible, the length of getting after this time slot finishes is e (n) value of n5, enters step 7.
Step 6: can judge that this basic frame is empty frame, i.e. free of data transmission.Disturb self-excitation to eliminate in order to be made an uproar in the end of repeater, the length of getting behind this basic frame end is e (n) value of n5, enters step 7.
Step 7: carry out normalization LMS algorithm, calculate iteration coefficient w i(n).Enter step 1 cycle detection.
The value of n1 in the described step, n2, n3, n4 and n5 is determined by the position of valid data in structure of time slot in the gsm system structure of time slot.
When a kind of GSM straight-forward station self-excitation interference elimination method that detects based on time slot carries out normalization LMS calculating, namely
Figure BDA0000067423850000061
W in the formula I+1(n) coefficient after the renewal, w i(n)
Coefficient value when not upgrading, u is the iteration convergence factor.e v(n) be valid data in the above-mentioned steps 3 detected time slot formats,
Figure BDA0000067423850000062
Be one section long e of sef-adapting filter exponent number v(n) vector. Summation for valid data e (n) mould of access square.
The above, only be in order to concrete case study on implementation of the present invention to be described, but be not in order to limit practical range of the present invention, such as those skilled in the art must be covered by the scope of claim of the present invention not breaking away from all equivalence changes of finishing under the indicated spirit of the present invention and the principle or modifying.

Claims (1)

1. GSM straight-forward station self-excitation interference elimination method that detects based on time slot is characterized in that may further comprise the steps:
Step 1, be mixed with the digital baseband signal of interference signal
Figure 2011101551402100001DEST_PATH_IMAGE002
With the prediction signal through sef-adapting filter output Subtract each other and obtain , namely
Figure DEST_PATH_IMAGE008
, judge
Figure 382473DEST_PATH_IMAGE006
The time slot feature, the valid data in the storage time slots use for back level algorithm; Wherein, digital baseband signal
Figure 548881DEST_PATH_IMAGE002
Be signal
Figure DEST_PATH_IMAGE010
With noise
Figure 2011101551402100001DEST_PATH_IMAGE012
Sum, namely
Figure 2011101551402100001DEST_PATH_IMAGE014
The time slot of described step 1 detects the following method of using:
Step S10, ask for
Figure 82280DEST_PATH_IMAGE006
Signal mode square, i.e. performance number
Figure DEST_PATH_IMAGE016
Step S11, according to the big or small setting power threshold value thresholding of input full power signal
Figure DEST_PATH_IMAGE018
, in real time relatively With
Figure 980277DEST_PATH_IMAGE018
Size, when in a time slot, be consecutively detected length more than or equal to
Figure DEST_PATH_IMAGE020
And smaller or equal to
Figure DEST_PATH_IMAGE022
Satisfy
Figure DEST_PATH_IMAGE024
Require
Figure 692755DEST_PATH_IMAGE006
The value, and be consecutively detected afterwards length more than or equal to Satisfy
Figure DEST_PATH_IMAGE028
Require
Figure 461253DEST_PATH_IMAGE006
During value, enter step S12; When in a time slot, being consecutively detected above length be Satisfy
Figure 640616DEST_PATH_IMAGE024
Require
Figure 509346DEST_PATH_IMAGE006
During value, enter step S13; When in a time slot duration, not satisfying above-mentioned two kinds of situations, enter step S14; If be consecutively detected above length in each time slot in continuous 8 time slots be Satisfy
Figure 564469DEST_PATH_IMAGE024
Require
Figure 25537DEST_PATH_IMAGE006
During value, enter step S15;
Step S12, constantly rise at interval satisfying condition
Figure DEST_PATH_IMAGE030
Begin peek in the time of constantly, get length and be
Figure DEST_PATH_IMAGE032
Figure 882811DEST_PATH_IMAGE006
Value is the valid data in the time slot
Figure DEST_PATH_IMAGE034
One section sequence, enter step S16;
Step S13, can judge and learn that this time slot is empty slot, wait for next frame arrival constantly, not update coefficients , deduct when counting down to a slot length
Figure 625901DEST_PATH_IMAGE022
During value, enter step S10;
Step S14, can't judge that this time slot is empty slot or normal time slot, because system feedback disturbs stack can't judge valid data in the time slot, in order to make algorithmic statement as early as possible, the length of getting after this time slot finishes is Value enters step S16;
Step S15, can judge and learn that this basic frame is empty frame that i.e. free of data transmission disturbs self-excitation to eliminate in order to be made an uproar in the end of repeater, the length of getting behind this basic frame end is
Figure 568078DEST_PATH_IMAGE032
Value enters step S16;
Step S16, carry out normalization LMS algorithm, calculate the iteration coefficient
Figure 441060DEST_PATH_IMAGE036
, enter step S10 cycle detection;
Step 2, the normalized LMS algorithm of employing,
Figure DEST_PATH_IMAGE038
, in the formula
Figure 250622DEST_PATH_IMAGE036
Be the iteration coefficient that calculates,
Figure DEST_PATH_IMAGE040
Be the weight coefficient after the iteration renewal,
Figure DEST_PATH_IMAGE042
Be convergence factor,
Figure 285636DEST_PATH_IMAGE034
For
Figure 675422DEST_PATH_IMAGE006
Valid data after time slot detects,
Figure DEST_PATH_IMAGE044
For
Figure 620245DEST_PATH_IMAGE034
One section vector value,
Figure DEST_PATH_IMAGE046
Be stored valid data length;
Step 3, the weight coefficient after iteration upgraded
Figure 287243DEST_PATH_IMAGE040
Coefficient input as sef-adapting filter produces noise after complex coefficient filtering
Figure 603692DEST_PATH_IMAGE012
The iteration estimated value
Figure 231507DEST_PATH_IMAGE004
, carry out self-excitation and disturb elimination.
2. the GSM straight-forward station self-excitation interference elimination method that detects based on time slot according to claim 1 is characterized in that: in the described step
Figure 527490DEST_PATH_IMAGE020
,
Figure 249328DEST_PATH_IMAGE026
,
Figure 727889DEST_PATH_IMAGE022
, With
Figure 189013DEST_PATH_IMAGE032
Value determined by the position of valid data in structure of time slot in the gsm system structure of time slot.
3. the GSM straight-forward station self-excitation interference elimination method that detects based on time slot according to claim 1 is characterized in that: in the described step 2 iterative formula Be one section valid data in the GSM/EDGE time slot format, its vector length is the exponent number of sef-adapting filter.
4. according to the described GSM straight-forward station self-excitation interference elimination method that detects based on time slot of one of claim 1-3, it is characterized in that: described method is applicable to the interference self-excitation elimination system of other time-division communication standard.
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