CN102223737A - 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 PDFInfo
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- CN102223737A CN102223737A CN2011101551402A CN201110155140A CN102223737A CN 102223737 A CN102223737 A CN 102223737A CN 2011101551402 A CN2011101551402 A CN 2011101551402A CN 201110155140 A CN201110155140 A CN 201110155140A CN 102223737 A CN102223737 A CN 102223737A
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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
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 interference eliminated method for designing of in detecting the GSM/EDGE time slot format, carrying out normalization LMS algorithm under the prerequisite of effective information.
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.Be provided with 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 (isolation-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 problem of gsm wireless repeater to 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 that are mixed with interference signal through sef-adapting filter output
Subtract each other and obtain e (n), promptly
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,
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 a convergence factor, e
v(n) be valid data after e (n) time slot detects,
Be e
v(n) one section vector value, N is a stored valid data length;
Step 3, the weight coefficient w after iteration upgraded
I+1(n), after complex coefficient filtering, produce the iteration estimated value of noise N (n) as the coefficient input of sef-adapting filter
Carry out the self-excitation interference eliminated.
Preferably, the time slot of above-mentioned steps one detects the following method of utilization:
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 the satisfy P of length afterwards more than or equal to n2
E (n)〉=P
ThreWhen the e (n) that requires is worth, enter step S12; When being consecutively detected in a time slot above length is the P that satisfies of n3
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 an 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 separates the vector amplitude error scope that timing can satisfy 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 of the present invention based on the time slot detection.
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)
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, promptly 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 the satisfy P of length afterwards more than or equal to n2
E (n)〉=P
ThreWhen the e (n) that requires is worth, enter step 3; When being consecutively detected in a time slot above length is the P that satisfies of n3
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 an 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, promptly
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,
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 being finished under indicated spirit of the present invention and the principle or modifying.
Claims (5)
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, the digital baseband signal d (n) and the prediction signal that are mixed with interference signal through sef-adapting filter output
Subtract each other and obtain e (n), promptly
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,
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 a convergence factor, e
v(n) be valid data after e (n) time slot detects,
Be e
v(n) one section vector value, N is a stored valid data length;
Step 3, the weight coefficient w after iteration upgraded
I+1(n), after complex coefficient filtering, produce the iteration estimated value of noise N (n) as the coefficient input of sef-adapting filter
Carry out the self-excitation interference eliminated.
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 the time slot of described step 1 detects the following method of utilization:
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 the satisfy P of length afterwards more than or equal to n2
E (n)〉=P
ThreWhen the e (n) that requires is worth, enter step S12; When being consecutively detected in a time slot above length is the P that satisfies of n3
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 an 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.
3. the GSM straight-forward station self-excitation interference elimination method that detects based on time slot according to claim 2, it is characterized in that: the value of the 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.
4. 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.
5. according to the described GSM straight-forward station self-excitation interference elimination method that detects based on time slot of one of claim 1-4, 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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| CN110932831A (en) * | 2019-10-28 | 2020-03-27 | 四川安迪科技实业有限公司 | TDMA time slot blind identification method and system |
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