CN100488182C - Method for real time intercepting carrier signal in short distance radio network - Google Patents

Method for real time intercepting carrier signal in short distance radio network Download PDF

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CN100488182C
CN100488182C CNB2006100664525A CN200610066452A CN100488182C CN 100488182 C CN100488182 C CN 100488182C CN B2006100664525 A CNB2006100664525 A CN B2006100664525A CN 200610066452 A CN200610066452 A CN 200610066452A CN 100488182 C CN100488182 C CN 100488182C
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value
phase shift
imaginary part
real part
signal
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CN1822579A (en
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张良
赵国栋
杨晨阳
胡志建
郦亮
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WEIXUNZIJING SCIENCE AND TECHNOLOGY Co Ltd BEIJING
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WEIXUNZIJING SCIENCE AND TECHNOLOGY Co Ltd BEIJING
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Abstract

Present invention relates to a real time detecting carrier signal method for receiving data in short distance wireless networks, belonging to wireless communication technology field. It contains first making before and after corresponding points conjugate multiplication calculation to two section baseband 2 times sampling received signal to obtain first group sequence, each value of said sequential multiplied by ej ( PI / 4) to obtain second group sequence, making phase shift operation respectively to each value in two group sequence, respectively accumulating, to calculate square value to two obtained accumulated value, selecting larger value as decision value, comparing said decision value with total energy statistics value of two section baseband times sampling received signal, comparing proportion value with threshold, thereby judging channel condition. Said method has advantages of reducing calculated amount and complexity in detecting process, increasing system implementation real time, reducing systematical energy consumption, and raising robustness of algorithm to system environments.

Description

The method of real-time sense of carrier signal in a kind of short-range wireless networking
Technical field
The present invention relates to the method for real-time sense of carrier signal in a kind of short-range wireless networking, belong to wireless communication technology field.
Background technology
In the communication protocol of the carrier sense multiple of avoiding based on band conflict, generally adopt the mechanism of real-time sense of carrier signal to intercept channel, with reduce with wireless network in the conflicting of uniformity signal.By detection to uniformity signal in the channel, judge whether channel occupied, with avoid with wireless network in the data transmitted clash, reach the purpose that improves network efficiency.In the communication protocol of the carrier sense multiple that the conflict based on band is avoided, real-time sense of carrier signal is extremely important to network service.
In real-time sense of carrier signal, the process of intercepting is exactly the detection signal process.Can utilize the modulating characteristic of signal to finish detection.Traditional real-time sense of carrier signal method is finished by demodulation mode, with the signal demodulation that receives, judges whether the signal of agreement regulation for this reason.In order to guarantee the accurate performance of demodulation, when numeric field is handled to received signal, generally need the above sample rate of 2 times of signal bandwidths to sample to received signal, produce distortion to prevent received signal when the digital received, thereby influence demodulation performance.In addition, for demodulation that can be good, system must carry out the synchronous and estimation on time and the frequency again to received signal, has strengthened the amount of calculation of real-time sense of carrier signal so again, has caused increasing substantially of power consumption.
In addition, most of communication protocol all has strict regulation to the time of finishing real-time sense of carrier signal, and traditional transfer to realize that based on separating the method for real-time sense of carrier signal must receive the preamble head of base band transmit, just can finish synchronously, demodulation, judge whether channel is idle, thereby the real-time that has caused intercepting descends, and also is difficult to satisfy simultaneously the requirement of communication protocol to the real-time sense of carrier signal time.
In order to carry out real-time sense of carrier signal, and reduce the complexity in the conventional intercepting method, need the new real-time sense of carrier signal algorithm of design the data that receive from any position of packet.
Summary of the invention
The objective of the invention is to propose the method for real-time sense of carrier signal in a kind of short-range wireless networking, satisfying under the prerequisite of performance, solve the complexity issue of real-time sense of carrier signal method.In the method for real-time sense of carrier signal, utilize the phase place relative position characteristic of the signal of modulating in the minimum shift keying mode, obtain whether existing in the current channel estimation of the signal of modulating in the minimum shift keying mode.
The method of real-time sense of carrier signal in the short-range wireless networking that the present invention proposes comprises following each step:
(1) receives the radiofrequency signal that transmitting terminal sends in the short-range wireless networking, carry out down-conversion, obtain base band 2 sampling received signals;
(2) any sampled point from above-mentioned received signal begins, and is the interval with the integral multiple chip period, reads the received signal of two sections random lengths;
(3) each sampled point in above-mentioned first section received signal is got conjugation, again with second section received signal in corresponding sampled point multiply each other, obtain first group of sequence, again each value in first group of sequence be multiply by respectively
Figure C200610066452D00041
Obtain second group of sequence;
(4) respectively each value in above-mentioned two groups of sequences is carried out the phase shift operation, obtain the 3rd, the 4th group of sequence;
(5) respectively the value in the 3rd, the 4th group of sequence after the above-mentioned phase shift is added up, and calculate the square value of two accumulated values, get wherein bigger square value as decision value;
(6) add up again after calculating the square value of the amplitude of all sampled points in two sections received signals of above-mentioned steps (2) respectively, two accumulated values that obtain are multiplied each other, obtain the gross energy statistical value of two sections received signals;
(7) ratio of above-mentioned decision value of calculating and above-mentioned gross energy statistical value is if this ratio greater than thresholding Y, then has carrier signal, if be less than or equal to thresholding Y, then carrier-less signal, wherein 0.5≤Y≤0.7.
In the said method, the process of each value in two groups of sequences being carried out phase shift operation is: according to the real part of each value in two groups of sequences and the positive and negative symbol of imaginary part, carry out phase shift. if the real part and the imaginary part of this value just are all, then with the value of initial value after as phase shift; If the real part of this value for negative, imaginary part for just, then real part that will be worth and imaginary part respectively take absolute value, and real part and imaginary part are intercoursed again, and obtain the value after the phase shift; . negative if the real part of this value and imaginary part are all, then respectively get the real part of this value and the absolute value of imaginary part, as the value after the phase shift; The real part and the imaginary part of getting mapping back correlation respectively are the real part of the preceding correlation of mapping and the absolute value of imaginary part; If the real part of this value for just, imaginary part is for bearing, then real part that will be worth and imaginary part respectively take absolute value, and real part and imaginary part are intercoursed again, and obtain the value after the phase shift.
The method of real-time sense of carrier signal in the short-range wireless networking that the present invention proposes has the following advantages:
(1) the present invention has utilized the modulating characteristic of signal to detect the signal of modulating in the minimum shift keying mode, and demodulation to received signal just can be finished real-time sense of carrier signal, has reduced the complexity of system.
(2) algorithm of real-time listening carrier signal can be from receiving any position of data among the present invention, when not required between and carrier wave synchronously with estimate, reduced the complexity of algorithm, improved the robustness of algorithm to system environments.
(3) the practical operation problem of the operation of the phase shift among the present invention combined with hardware can become the needed complex multiplication operation of traditional phase shift simple symbol decision and swap operation and realize, has reduced amount of calculation significantly;
(4) the inventive method is not subjected to the influence of carrier frequency bias size, has reduced the requirement of algorithm to The Hardware Design, has reduced the amount of calculation of algorithm.
Description of drawings
Fig. 1 is the principle schematic of the inventive method.
Fig. 2 is waveform and two kinds of possible sampling locations of 2 sampling received signals in the inventive method.
Specific implementation method
The method of real-time sense of carrier signal at first receives the radiofrequency signal that transmitting terminal sends in the short-range wireless networking in the short-range wireless networking that the present invention proposes, and carries out down-conversion, obtains base band 2 sampling received signals; Any sampled point from received signal begins, and is the interval with the integral multiple chip period, reads the received signal of two sections random lengths; Each sampled point in first section received signal is got conjugation, again with second section received signal in corresponding sampled point multiply each other, obtain first group of sequence, again each value in first group of sequence be multiply by respectively
Figure C200610066452D00051
Obtain second group of sequence; Respectively each value in two groups of sequences is carried out the phase shift operation, obtain the 3rd, the 4th group of sequence; Respectively the value in the 3rd after the phase shift, the 4th group of sequence is added up respectively, calculate the square value of two accumulated values respectively, get wherein bigger square value as decision value; Add up again after calculating the square value of the amplitude of all sampled points in above-mentioned two sections received signals respectively, two accumulated values that obtain are multiplied each other, obtain the gross energy statistical value of two sections received signals; Calculate the ratio of decision value and gross energy statistical value, if this ratio greater than thresholding Y, then has carrier signal, if be less than or equal to thresholding Y, then carrier-less signal, wherein 0.5≤Y≤0.7.
In the method for above-mentioned real-time sense of carrier signal, the process of each value in two groups of sequences being carried out the phase shift operation is: according to the real part of each value in two groups of sequences and the positive and negative symbol of imaginary part, carry out phase shift, if the real part and the imaginary part of this value just is all, then with the value of initial value after as phase shift; If the real part of this value for negative, imaginary part for just, then real part that will be worth and imaginary part respectively take absolute value, and real part and imaginary part are intercoursed again, and obtain the value after the phase shift; If it is negative that the real part of this value and imaginary part are all, then respectively get the real part of this value and the absolute value of imaginary part, as the value after the phase shift; The real part and the imaginary part of getting mapping back correlation respectively are the real part of the preceding correlation of mapping and the absolute value of imaginary part; If the real part of this value for just, imaginary part is for bearing, then real part that will be worth and imaginary part respectively take absolute value, and real part and imaginary part are intercoursed again, and obtain the value after the phase shift.
Introduce one embodiment of the present of invention in detail below in conjunction with accompanying drawing:
In the Radio Network System based on the IEEE802.15.4b standard, transmit and adopt the strong control of minimum phase shift modulation system, the phase place that transmits like this is along with the time is continually varying, avoided SPA sudden phase anomalies, reduced signal bandwidth frequency response in addition, and the complex signal mould value perseverance after the modulation is 1, can be expressed as S i = e j θ i , Be that local frequency expansion sequence only has relation with phase place.Be expressed as complex signal as shown in Figure 2, the real part of complex signal is represented on I road wherein, and Q represents on the road imaginary part of complex signal.Therefore the phase place of complex signal has just been represented the relativeness of signal real part and imaginary part.
In an embodiment of the present invention, the modulation scheme definite according to this standard, receive the radiofrequency signal that transmitting terminal sends in the short-range wireless networking, after carrying out down-converted, obtain baseband receiving signals through 2 samplings, from Fig. 1 (a) and Fig. 2 as can be seen, 2 sampling signals sampling points can be divided into two groups of sampling locations, 1 position sampling point (representing with zero) and 2 position samplings point (representing with △).Sampled point for 1 position has only 0, pi/2, π, four kinds of phase places of 3 pi/2s; Sampled point for 2 sampling locations has only π/4,3 π/4,5 π/4,7 π/4 four kind of phase place.And for the sampled point of every group of sampling location, the mutual transformational relation of the phase place between them has only 1 ,-1, and I ,-I four kinds may.
Because relevant received signal is the received signal of two sections random lengths that the integral multiple chip period reads of being separated by before and after being used for doing, be designated as S from the received signal of 2 samplings 1And S 2Here can select the interval of two segment datas and the length of two segment datas in the 802.15.4b system all is a frequency expansion sequence cycle.So can guarantee that when this two segment signal is done the corresponding points conjugate multiplication sampled point of two sampling locations is corresponding separately.These two sections received signals are done the front and back conjugate multiplication, obtain first group of sequence:
r i = s i · s i + L ′ i = 1,2 , · · · , L
R wherein iBe first group of value in the sequence, s iBe the sampled point of 2 sampling baseband receiving signals, L is the sampled point number in the frequency expansion sequence cycle.
The phase place of the value of the first group of sequence that at this moment obtains has only 0, pi/2, and π, four kinds of 3 pi/2s are shown in Fig. 1 (b).Each correlation to first group of sequence multiply by respectively again
Figure C200610066452D00061
Its phase place unification is rotated counterclockwise 45 degree, obtains second group of sequence, its phase place has only π/4,3 π/4,5 π/4,7 π/4 four kind of value, shown in Fig. 1 (c).
Respectively each value of top two groups of sequences is done the phase shift operation then, at first judge the symbol of each value real part and imaginary part in two groups of sequences, be weighted phase shift according to the result who judges by table 1 rule then, each correlation phase place is all moved first quartile, obtain third and fourth group of sequence, as Fig. 1 (d) with (e).
Respectively third and fourth group of sequence added up respectively, respectively accumulated value is asked square then, relatively both sizes are selected the statistical value of bigger value as the received signal correlation, are designated as R.
Add up again after calculating the square value of two sections received signal amplitudes that read previously then respectively, two accumulated values that obtain are multiplied each other, obtain the gross energy statistical value of two sections received signals, be designated as P.
P = Σ i = 1 L ( s i ′ s i ) Σ i = 1 L ( s i + L ′ s i + L )
At last, calculate the ratio R/P of above-mentioned two statistics, if this ratio greater than thresholding Y, then has carrier signal, if be less than or equal to thresholding Y, then carrier-less signal, wherein 0.5≤Y≤0.7.
Hard-wired bit manipulation of table 1 and phase place are judged the mapping table of parameter
Quadrant Real part Imaginary part The phase shift operating procedure
I + + Need not operate
II - + Earlier the address of real part and imaginary part is exchanged real part negate then
III - - The negate respectively of real part imaginary part
IV + - Earlier the address of real part and imaginary part is exchanged imaginary part negate then

Claims (2)

1, the method for real-time sense of carrier signal in a kind of short-range wireless networking is characterized in that this method comprises following each step:
(1) receives the radiofrequency signal that transmitting terminal sends in the short-range wireless networking, carry out down-conversion, obtain base band 2 sampling received signals;
(2) any sampled point from above-mentioned received signal begins, and is the interval with the integral multiple chip period, reads the received signal of two sections random lengths;
(3) each sampled point in above-mentioned first section received signal is got conjugation, again with second section received signal in corresponding sampled point multiply each other, obtain first group of sequence, again each value in first group of sequence be multiply by respectively
Figure C200610066452C0002101927QIETU
, obtain second group of sequence;
(4) respectively each value in above-mentioned two groups of sequences is carried out the phase shift operation, obtain the 3rd, the 4th group of sequence;
(5) respectively the value in the 3rd, the 4th group of sequence after the above-mentioned phase shift is added up, and calculate the square value of two accumulated values, get wherein bigger square value as decision value;
(6) add up again after calculating the square value of the amplitude of all sampled points in two sections received signals of above-mentioned steps (2) respectively, two accumulated values that obtain are multiplied each other, obtain the gross energy statistical value of two sections received signals;
(7) ratio of above-mentioned decision value of calculating and above-mentioned gross energy statistical value is if this ratio greater than thresholding Y, then has carrier signal, if be less than or equal to thresholding Y, then carrier-less signal, wherein 0.5≤Y≤0.7.
2, the method for claim 1 is characterized in that the wherein said process that each value in two groups of sequences is carried out phase shift operation is: if the real part and the imaginary part of institute's value just are all, then with the value of initial value after as phase shift; If the real part of institute's value for negative, imaginary part for just, then real part and the imaginary part with institute's value respectively takes absolute value, and real part and imaginary part intercoursed again, and obtains the value after the phase shift; If it is negative that the real part of institute's value and imaginary part are all, then respectively get the real part of institute's value and the absolute value of imaginary part, obtain the value after the phase shift; If the real part of institute's value for just, imaginary part is for bearing, then real part and the imaginary part with institute's value respectively takes absolute value, and real part and imaginary part intercoursed again, and obtains the value after the phase shift.
CNB2006100664525A 2006-03-31 2006-03-31 Method for real time intercepting carrier signal in short distance radio network Expired - Fee Related CN100488182C (en)

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CN101594280B (en) * 2008-05-27 2011-05-04 北京威讯紫晶科技有限公司 Method for real-time sense of carrier signal in wireless network
CN101494635B (en) * 2009-03-06 2011-06-08 北京威讯紫晶科技有限公司 Time frequency synchronization method of short distance wireless network
CN106161295A (en) * 2015-04-27 2016-11-23 晨星半导体股份有限公司 Dynamic channel condition discriminating apparatus and method

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CN1578239A (en) * 2003-07-29 2005-02-09 三星电子株式会社 Medium access control in wireless local area network
CN1602017A (en) * 2004-09-02 2005-03-30 上海交通大学 Realtime medium access control method compatible with ethernet
CN1649318A (en) * 2004-01-26 2005-08-03 三星电子株式会社 Method and apparatus for setting, transmitting and receiving data for virtual carrier sensing in wireless network communication
CN1747345A (en) * 2005-10-28 2006-03-15 北京威讯紫晶科技有限公司 Synchronous process for receiving data in short-range wireless network

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1578239A (en) * 2003-07-29 2005-02-09 三星电子株式会社 Medium access control in wireless local area network
CN1649318A (en) * 2004-01-26 2005-08-03 三星电子株式会社 Method and apparatus for setting, transmitting and receiving data for virtual carrier sensing in wireless network communication
CN1602017A (en) * 2004-09-02 2005-03-30 上海交通大学 Realtime medium access control method compatible with ethernet
CN1747345A (en) * 2005-10-28 2006-03-15 北京威讯紫晶科技有限公司 Synchronous process for receiving data in short-range wireless network

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