CN104065603B - Raised cosine sends the quadrature phase shift keying signal automatic-identifying method under molding and multi-path environment - Google Patents
Raised cosine sends the quadrature phase shift keying signal automatic-identifying method under molding and multi-path environment Download PDFInfo
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Abstract
The present invention relates to a kind of channels to communicate between transmitting and receiver to have multipath effect, and transmitting terminal have raised cosine send formed filter it is existing under the premise of quadrature phase shift keying signal automatic-identifying method, the communication system transmit-receive model that molding filtration is sent with raised cosine is constructed first, and obtain the reception signal quadravalence cyclic cumulants expression formula under multipath conditions, main path is set and simplifies obtained cyclic cumulants expression formula according to raised cosine property, ideal sort feature vector value is constructed according to the mpsk signal cyclic cumulants useful information of acquisition, according to the cube of raised cosine shaping function, waveform after bipyramid and delay carries out rejecting cyclic cumulants interference information, it is final to realize quadrature phase shift keying signal automatic identification.The present invention is realized to quadrature phase shift keying signal automatic identification, is offered convenience to the communication interconnection between more systems.
Description
Technical Field
The invention relates to the technical field of signal processing of wireless communication, in particular to an automatic identification method for quadrature phase shift keying signals on the premise that a channel between a communication transmitting end and a receiving end has a multipath effect and a sending end has a raised cosine sending forming filter.
Background
With the continuous development of mobile wireless communication technology, various communication standards appear, signal modulation modes are more and more diversified, and the problem of automatic identification of modulation becomes a prerequisite for correct demodulation of signals. The goal of future radio is to determine it to be a system with characteristics of multiple frequency bands, multiple functions, multiple systems, reconfigurable, etc.; therefore, it is required to correctly judge the modulation mode of the communication signal on the premise of unknown modulation mode information, to implement automatic identification of the modulation mode, to estimate the related communication parameters and to reconstruct the radio receiving system in real time, to create conditions for further recovering the signal and to implement automatic reception of the signal. In the conventional communication system, because the modulation pattern is single, once two communication parties start up, the two communication parties wait on the predicted modulation pattern without recognizing the modulation signal. With the rapid development of digital communication, a situation that a plurality of communication systems coexist is formed, and the modulation modes and access technologies of the communication systems are different, so that a great obstacle is brought to communication interconnection among the plurality of systems. The communication signal automatic identification technology can automatically identify the modulation mode of a communication signal, and the multi-mode requirement of future radio causes that two communication parties cannot wait for receiving on a specific modulation mode, and unless the prior agreement is carried out, the specific modulation mode and the parameters of the signal must be firstly identified before the signal is received and demodulated, so that the information can be demodulated. The problem of automatic signal identification is a key technology in radio, and is also an important technical basis for a general receiver and an intelligent modem forming the radio.
On the other hand, in most practical communication systems, the channel characteristics are unknown, and in many cases, the channel response is time-varying; meanwhile, in order to reduce the frequency band occupied by the signal and reduce the intersymbol interference, a square root raised cosine filter is generally adopted for the transmitting filter, and the parameters of the filter are often unknown at a software radio receiving end. In addition, due to reflections off the ground and surrounding buildings, the transmitted signal often arrives at the receiving antenna at different times via multiple different paths. These arriving waves become multipath waves, and due to the difference of their intensity, propagation time, and bandwidth of the transmission channel, the amplitude and phase of the synthesized received signal, even the waveform, may vary greatly, causing distortion or fading phenomena.
Disclosure of Invention
The invention aims to solve the problem of automatic signal identification on the premise that a channel between communication transmission and a receiver has a multipath effect and a raised cosine transmission molding filter exists at a transmitting end, and provides a raised cosine transmission molding and automatic quadrature phase shift keying signal identification method in a multipath environment.
In order to achieve the purpose, the invention provides the following technical scheme: a raised cosine transmission molding and orthogonal phase shift keying signal automatic identification method under multipath environment is carried out according to the following steps:
the method comprises the following steps: constructing a communication system transceiving model with raised cosine transmission shaping filtering,
binary signal a (k) is converted into modulated signal s (k) after being coded and modulated by MPSK, modulated signal s (k) is transmitted to a pulse shaping filter p (a, t) at a transmitting end through roll-off, modulated signal s (k) is converted into analog high-frequency signal s (t) through carrier waves, and is received and converted into receiving baseband signal x (k) by a receiver after passing through multipath fading channel h (t, ξ) of propagation environment, the radio receiver receives modulated signal s (k), and signal waveform polluted by noise is obtained after preprocessing as follows:
wherein,representing a convolution operation, akFor a modulated baseband signal, s (T) is the transmitted signal, h (T) is the unknown channel impulse response, p (T) is the energy normalized transmitted symbol waveform, E is the symbol energy, TsIs the symbol width, t0Is a timing error; f. ofcIs carrier frequency, N is code element number of observation interval, v (t) is noise;
step two: obtaining a fourth-order cyclic accumulation expression of the received signal under the multipath condition,
the received signal under the influence of a multipath fading environment discusses the two-path case, namely:
h(ξ)＝h0(ξ)δ(ξ-ξ0)+h1(ξ)δ(ξ-ξ1)
where δ represents the Dirac function, h0And h1representing the amplitude of path 1 and path 2, respectively, ξ represents time, ξ0indicating the moment of occurrence, ξ, of path 11Represents the appearance time of the path 2;
the expression of the fourth-order cyclic accumulation quantity of the received signal under the multipath condition is obtained as follows:
step three: setting a main path and simplifying the obtained cyclic cumulant expression according to the properties of raised cosine function, and setting the first path as the main path, namely setting h0(ξ0) And (3) when the other paths are 1, the additional delay factor vector of each path relative to the main path is as follows:
Δξ＝[Δξ0，Δξ1，…，ΔξL-1]
when beta is B/TsB is an integer, and the raised cosine function is a real number, so that the following s (t) cyclic cumulative quantity function is obtained:
obtaining the value of tau, beta and T no matter whether m is 0,1 or 2sWhen the value is constant, the value of the above formula is only related to the cumulant Ca，n，mOn the other hand, it follows that:
in one form:
and is provided with:in the case of the item I, the first,is item II;
II, the formula:
and is provided with:in the case of the item I, the first,
is item II;
the third formula is as follows:
and is provided with:in the case of the item I, the first,is item II;
step four: constructing ideal classification characteristic vector values according to the acquired useful information of the MPSK signal circulation cumulant,
τ＝[0，0，0，0]，then, obtaining:
Fr＝[fr1，fr2]
and constructing ideal classification eigenvector values as follows: when the modulation signal is BPSK, the feature vector F is classifiedr＝[fr1，fr2]Is [1, 1]]When the modulation signal is QPSK, the feature vector F is classifiedr＝[fr1，fr2]Is [1, 0]]When the modulation signal is 8PSK, the feature vector F is classifiedr＝[fr1，fr2]Is [0, 0]]；
Step five: according to the third power and the fourth power of raised cosine shaping function and delayed waveform to eliminate circulating cumulant interference information,
1) additional time delay delta xiivaries between 1 and 10us, and an additional time delay delta xiiTypical values of (D) vary between 10-30 us, and for example, the IS-95 system symbol rate IS 1.288Mchip/s, WCDMA IS 4.096Mchip/s, CDMA2000 IS 1.2288 or 3.6864Mchip/s, and TD-SCDMA IS 1.1136 Mchip/s; it can be seen that the symbol period of the CDMA system has reached Ts< 1us, and the bandwidth required by future mobile communication is wider and wider, and is faster and faster relative to the code element rate; on the other hand, the raised cosine shaping function is considered to meet the Nyquist criterion; it is easy to find that when (I ═ 0,1, …, Q-1) with the values of item II in all of the equations in step three, two and three being infinitely smaller than the value of item I, the influence of item II in the equations in step three, two and three can be completely ignored;
2) and 2Ts≤Δξi＜4TsWhen the identification accuracy is high, the attenuation parts of the raised cosine shaping functions have certain intersection, and the II terms in the first, second and third formulas have certain influence on the identification accuracy;
3) discussion 0 < Δ ξi＜2TsIn the case of the hour, the three formulas are one, two and threeThe influence of item II on the identification accuracy rate cannot be ignored, and the interference degree is influenced by the combination of the amplitude, the phase drift, the delay function and the raised cosine shaping function p (t) of the multipath path.
By adopting the technical scheme, the channel between the communication transmitter and the receiver has the multipath effect, and the sending end has the automatic identification method of the quadrature phase shift keying signal under the premise of the raised cosine transmission forming filter, firstly, a communication system transceiving model with the raised cosine transmission forming filter is constructed, a received signal fourth-order circulation cumulant expression under the multipath condition is obtained, a main path is set, the obtained circulation cumulant expression is simplified according to the property of the raised cosine function, an ideal classification characteristic vector value is constructed according to the obtained useful information of the MPSK signal circulation cumulant, circulation cumulant interference information is removed according to the third power, the fourth power and the delayed waveform of the raised cosine forming function, and the automatic identification of the quadrature phase shift keying signal is finally realized; the method realizes automatic identification of the orthogonal phase shift keying signals, has high identification accuracy, and brings convenience to communication interconnection among multiple systems.
The following is further detailed in conjunction with the accompanying drawings.
Drawings
FIG. 1 is a system model of an embodiment of the present invention;
FIG. 2 is a schematic diagram of QPSK and 8PSK signal constellations in accordance with an embodiment of the present invention;
FIG. 3 shows normalized QPSK modulated signal after being shaped and filtered by roll-off factor of 0.1A modulus value;
fig. 4 shows a prototype α of the raised cosine shaping function p (t) of 0.1, a third power, a fourth power and a delayed waveform, wherein the symbol period is 1 us;
fig. 5 is a sample of a multipath synthesized channel used in an experimental case of an embodiment of the present invention;
FIG. 6 illustrates Ω of an embodiment of the present inventionPSKClassifying and identifying { BPSK, QPSK and 8PSK }, and adding a delay factor to influence the identification performance;
FIG. 7 is Ω of an embodiment of the present inventionPSKThe method comprises the following steps of (1) classifying and identifying { BPSK, QPSK, 8PSK }, wherein the influence of amplitude attenuation coefficients on identification performance is caused;
FIG. 8 is Ω of an embodiment of the present inventionPSKThe performance is influenced by the number of multipath by { BPSK, QPSK, 8PSK } classification identification;
FIG. 9 is Ω of an embodiment of the present inventionPSKThe impact of multipath channel path phase drift on identification performance, classified { BPSK, QPSK, 8PSK }.
Detailed Description
Referring to fig. 1 to 9, in order to make a baseband signal as close to ideal as possible during actual transmission in a wireless communication system, a variety of waveform shaping techniques are generally used, and a roll-off Raised Cosine (RC) filter is a representative one of them, and is designed according to Nyquist criterion; the invention discloses a raised cosine transmission molding and automatic identification method of quadrature phase shift keying signals under a multipath environment, which comprises the following steps:
the method comprises the following steps: constructing a communication system transceiving model with raised cosine transmission molding filtering;
the system model is shown in fig. 1, a binary signal a (k) is converted into a modulated signal s (k) after being coded and modulated by MPSK, then the modulated signal s (k) is changed to pass through a roll-off sending pulse shaping filter p (a, t) (where a is a roll-off factor and generally takes a value in the range of [0, 1], and t represents time) at a sending end, then the signal is converted into an analog high-frequency signal s (t) through a carrier, finally the analog high-frequency signal s (t) passes through a multipath fading channel h (t, ξ) of a propagation environment, is received by a receiver and becomes a received baseband signal x (k) after corresponding inverse transformation, and then the automatic identification of a modulation mode is carried out through a modulation automatic identification module, wherein the receiver adopted by the invention is just the existing ordinary receiver, such as a mobile phone and the like, so the transformation method thereof is also a known technology which is well known by ordinary.
Where E is the average power of the sequence, akThe method is a code element sequence with normalized signal average power in a received signal, wherein A is amplitude, and M is a modulation type order; it is assumed that the transmitted sequences are independently and equally distributed.
The time domain expression of the RC filter is as follows:
wherein α is raised cosine roll-off factor with the value between [0, 1]T issgenerally, the channel impulse has generalized stationarity in a short time or a short distance, or is considered as a time-invariant system, then the channel impulse response can be simplified as follows:
in the formula [ theta ]iFor unknown residual phase offset after carrier extraction, for convenience of discussion and presentation hereinafter, the above equation is rewritten as:
whereinWhere π is the circumference ratio, fcis the carrier frequency, ξiTime of remaining phase deviation, hiIs the amplitude.
the received signal x (t) may be represented as the convolution of the transmitted signal s (t) with the time-varying channel impulse response h (t, ξ), i.e.Now, assuming that the channel environment is a multipath channel with unknown channel parameters, the symbol rate is known, and the receiver completes carrier synchronization, but there may be an unknown reference phase offset. The radio receiver receives the modulated signal s (k), and after preprocessing such as carrier extraction, down-conversion and low-pass filtering, the signal waveform contaminated by noise can be represented as follows:
here, theRepresenting a convolution operation, akIs a modulated baseband signal; s (t) is the transmitted signal; h (t) is the unknown channel impulse response; p (t) is a transmitted code element waveform with energy normalization, such as a common raised cosine function; e is the symbol energy; t issIs the symbol width; t is t0Is a timing error; f. ofcFor the carrier frequency, after the carrier extraction at the receiving end, there is a possible carrier frequency deviation, for the convenience of analysis, the deviation is not considered, i.e. Δ f in the upper formula after the carrier extraction is setc0; v (t) is noise; n is the number of symbols in the observation interval.
Step two: obtaining a fourth-order cyclic cumulant expression of a received signal under the multipath condition;
without loss of generality, the received signal under the influence of multipath fading environment discusses the two-path case, namely:
h(ξ)＝h0(ξ)δ(ξ-ξ0)+h1(ξ)δ(ξ-ξ1)
where δ represents the Dirac function, h0And h1representing the amplitude of path 1 and path 2, respectively, ξ represents time, ξ0indicating the moment of occurrence, ξ, of path 11Indicating the time of occurrence of path 2.
According to the nature of the cumulative amount of cycles: let the filter impulse response be h (t), if:
whereinDenotes a convolution operation, τ ═ τ0，τ1，…，τn-1]，λ＝[λ0，λ1，…，λn-1]and β is a cycle frequency index.
The derivation yields:
wherein τ ═ τ [ τ ]0，…，τn-1]，λ＝[λ0，…，λn-1]，(*)jIs arbitrary conjugation, and m is the total number of conjugation.
substituting h (t, ξ) into the four-order cumulant invariant class feature vector:
continue to expand the above formula and omit h1The higher power terms of (a) yield:
combining the weighted properties of the Dirac function: if f (t) is one, when t is equal to t0A time-continuous ordinary function, then f (t) delta (t-t)0)＝f(t0)δ(t-t0) The above formula then translates to:
then, the above equation is further simplified according to the definition of the Dirac function:
the first term of the above equation is the input and output cyclic accumulation relation of an ideal channel, and the rest terms are interference terms introduced by multipath influence; taking τ ═ 0,0, 0,0 and according to the symmetric nature of the accumulation with respect to the variables, the above equation reduces to:
the same can get:
wherein Re (-) is the operation of the real part.
Step three: setting a main path and simplifying the obtained cyclic cumulant expression according to the properties of raised cosine function;
without the first diameter being the main diameter, i.e. h0(ξ0) And (3) when the other paths are 1, the additional delay factor vector of each path relative to the main path is as follows:
Δξ＝[Δξ0，Δξ1，…，ΔξL-1]
the following equation can be obtained:
when beta is B/TsAnd B is an integer, resulting in an s (t) cyclic accumulation function as follows:
since the raised cosine function is real, the above equation is rewritten as:
when the value of tau, β and T is found to be 0,1 and 2 no matter the value of msWhen the value is constant, the value of the above formula is only related to the cumulant Ca，n，mIt is related. Further comprising:
thus, there are:
in one form:
and is provided with:in the case of the item I, the first,is item II;
II, the formula:
and is provided with:in the case of the item I, the first,
is item II;
the third formula is as follows:
and is provided with:in the case of the item I, the first,is item II;
the QPSK modulation signal is normalized through a signal after shaping and filtering with a roll-off factor of 0.1the modulus is shown in FIG. 2, and the results in FIG. 2 can be seen when β ═ B/TsB is an integer, normalizedThe modulus value of (a) is maximum.
Step four: constructing an ideal classification characteristic vector value according to the acquired useful information of the MPSK signal circulation cumulant;
with τ being [0,0, 0,0 ═ 0]；And the requirements can be met. Considering that the first term is the input-output cyclic accumulation relation of the ideal channel, i.e. useful information, it is easy to obtain:
Fr＝[fr1，fr2]
the ideal MPSK classification feature vector values are constructed as shown in table 1:
TABLE 1
The kind of the corresponding modulation scheme can be determined according to table 1.
Step five: according to the third power, the fourth power and the delayed waveform of the raised cosine shaping function, removing the circulating cumulant interference information;
fig. 4 shows the third power, the fourth power and the delayed waveform of the raised cosine shaping function, and it can be seen from the graph that when the delay exceeds a certain range, the multiplication of the third power and the delayed waveform of the raised cosine shaping function can be approximate to zero. The analysis was carried out in three cases:
1) in practical wireless communication systems in urban and suburban areas, an additional time delay delta xiiTypical values of (1-10 us), additional time delay IS much larger in mountainous areas of villages, typical values of the additional time delay are varied between 10-30 us, and for example, the IS-95 system symbol rate IS 1.288Mchip/s, WCDMA IS 4.096Mchip/s, CDMA2000 IS 1.2288 or 3.6864Mchip/s, and TD-SCDMA IS 1.1136 Mchip/s; it can be seen that the symbol period of the CDMA system has reached Ts< 1us, and the bandwidth required by future mobile communication is wider and wider, and is faster and faster relative to the code element rate, on the other hand, considering that the raised cosine shaping function meets the Nyquist criterion, it is easy to find when delta xii≥4Ts(I-0, 1, …, Q-1) with the values of item II in all of the third, second and third steps being infinitely less than the value of item I, the effect of item II in the third, second and third steps can be completely ignored; the classification method has strong robustness for the identification of the actual communication system.
2) And 2Ts≤Δξi＜4TsAt the time, the decaying part of the raised cosine shaping function has a certain intersection,the item II in the third, second and third formulas has certain influence on the accuracy of signal identification.
3) if exactly 0 < Δ ξ is discussed theoreticallyi＜2TsIn the time situation, the influence of item II in one, two and three of the steps cannot be ignored, and the degree of interference is influenced by the combination of the amplitude, phase drift, delay function and raised cosine shaping function p (t) of the multipath path, because of many influencing factors, the situation is more complicated.
In this step, the two cases 2) and 3) are theoretical cases, and will not occur in the subsequent communication, so the two cases 2) and 3) can be ignored.
Sending omega according to step onePSKAny one signal of { BPSK, QPSK, 8PSK } is obtained, and the following simulation experiment is carried out according to the steps one to five in the invention:
simulation example
fig. 5 is a sample of a multipath synthesized channel, and the following simulations are all performed on the premise of the sample, the multipath channel adopted by the simulation is provided, the roll-off factor α is 0.1, and the specific parameters are h0＝1，h1＝-0.7，Δξ＝[Ts/3]，h0＝1，h1＝-0.7，Δξ＝[Ts/2]，h0＝1，h1＝0.4，Δξ＝[Ts/3]。
Simulation experiment 1:
ΩPSKthe method comprises the following steps of (1) classifying and identifying { BPSK, QPSK and 8PSK }, wherein a delay factor is added to influence on identification performance, and the data volume is 500; 200 Monte Carlo experiments; the simulation adopts the path number of 2, h0＝1，h1＝-0.7；The results are shown in FIG. 6.
the simulation results of FIG. 6 illustrate when Δ ξ isi＞2TsThe influence of the interference term is negligible, and the identification thereofperformance is not substantially affected by it when Δ ξi≤2TsThe accuracy of identification is reduced most obviously; the accuracy of signal identification by the method is 100%.
Simulation experiment 2:
ΩPSKthe method comprises the following steps of (1) classifying and identifying { BPSK, QPSK and 8PSK }, wherein the amplitude attenuation coefficient influences the identification performance, and the data volume is 500; 200 Monte Carlo experiments; the number of the simulation adopted paths is 2, and the paths are respectively takenh1＝-0.7，0.3；Δξ＝[3Ts]，h0＝1，h10.7, -0.5, 0.3, the simulation results of fig. 7 illustrate Δ ξi≥2TsAnd meanwhile, the influence of the amplitude attenuation coefficient on the signal identification accuracy is not great.
Simulation experiment 3:
ΩPSKthe { BPSK, QPSK, 8PSK } classification identification, the influence of the number of multipath channel paths on the performance, the multipath channel parameters are respectively: 2, diameter: h is0＝1，h1＝-0.7，Δξ＝[Ts/3]And 3, diameter: h is0＝1，h1＝-0.7，h2＝0.6，[Δξ＝Ts/3，Ts/4]And 5, diameter: h is0＝1，h1＝-0.7，h2＝0.6，h3＝-0.4，h4＝0.2；Δξ＝[Ts/3，Ts/4，Ts/3，Ts/2]
From the simulation results of fig. 8, it is found that an increase in the number of paths does not mean a decrease in the identification performance, because the propagation delays of different signals cause a difference in the phase of the signals, so that the amplitude of the received signal is sometimes increased by in-phase superposition and sometimes decreased by anti-phase superposition. The interference superposition effect of the interference terms in the discriminant may thereby be increased or decreased.
Simulation experiment 4:
FIG. 9 showsGo out omegaPSKThe method comprises the following steps that (1) classification is carried out according to { BPSK, QPSK and 8PSK }, the influence of multipath path phase drift and amplitude fading coefficients on identification performance is carried out, and 2 paths, the data volume is 500, the amplitude fading coefficients and the phase drift are all generated randomly; the phase is [ -2 π, 2 π]Randomly generated, and amplitude fading coefficient is from [ -0.9, 0.9]Randomly generated with additional delay factor from 0.1Ts，10Ts]And (4) randomly generating.
Claims (1)
1. A raised cosine transmission molding and orthogonal phase shift keying signal automatic identification method under multipath environment is carried out according to the following steps:
the method comprises the following steps: constructing a communication system transceiving model with raised cosine transmission shaping filtering,
binary signal a (k) is converted into modulated signal s (k) after being coded and modulated by MPSK, modulated signal s (k) is transmitted to a pulse shaping filter p (α, t) at a transmitting end through roll-off, modulated signal s (k) is converted into analog high-frequency signal s (t) through carrier waves, and is received and converted into receiving baseband signal x (k) by a receiver after passing through multipath fading channel h (t, ξ) of propagation environment, the radio receiver receives modulated signal s (k), and signal waveforms polluted by noise are obtained after preprocessing as follows:
wherein,representing a convolution operation, akFor a modulated baseband signal, s (T) is the transmitted signal, h (T) is the unknown channel impulse response, p (T) is the energy normalized transmitted symbol waveform, E is the symbol energy, TsIs the symbol width, t0Is a timing error; f. ofcis carrier frequency, N is number of code elements in observation interval, v (t) is noise, k is k-th code element, α is raised cosine roll-off factor, delta fc＝0；Representing an initial phase;
step two: obtaining a fourth-order cyclic accumulation expression of the received signal under the multipath condition,
the received signal under the influence of a multipath fading environment discusses the two-path case, namely:
h(ξ)＝h0(ξ)δ(ξ-ξ0)+h1(ξ)δ(ξ-ξ1)
where δ represents the Dirac function, h0And h1representing the amplitude of path 1 and path 2, respectively, ξ represents time, ξ0indicating the moment of occurrence, ξ, of path 11Represents the appearance time of the path 2;
the expression of the fourth-order cyclic accumulation quantity of the received signal under the multipath condition is obtained as follows:
where Re (-) is the operation of the real part, β is the cyclic frequency index, β is the conjugate, the cyclic accumulation function of the sequence s (t) after the transmitted pulse is shapedp (.) is a roll-off transmit pulse shaping filter;
step three: setting a main path and simplifying the obtained cyclic cumulant expression according to the properties of raised cosine function, and setting the first path as the main path, namely setting h0(ξ0) And (3) when the other paths are 1, the additional delay factor vector of each path relative to the main path is as follows:
Δξ＝[Δξ0,Δξ1,…,ΔξL-1]
l represents the total number of multipath paths;
when beta is B/TsB is an integer, the raised cosine function is a real number, and n is 4, resulting in the following s (t) cyclic accumulation function:
obtaining the value of tau, beta and T no matter whether m is 0,1 or 2sWhen the value is constant, the value of the above formula is only related to the cumulant Ca,n,mOn the other hand, it follows that:
in one form:
and is provided with:in the first item, the first and second groups,item II;
II, the formula:
and is provided with:in the first item, the first and second groups,
item II;
the third formula is as follows:
and is provided with:in the first item, the first and second groups,item II;
step four: constructing ideal classification characteristic vector values according to the acquired useful information of the MPSK signal circulation cumulant,
τ＝[0,0,0,0]，then, obtaining:
Fr＝[fr1,fr2]
and constructing ideal classification eigenvector values as follows: when the modulation signal is BPSK, the feature vector F is classifiedr＝[fr1,fr2]Is [1, 1]]When the modulation signal is QPSK, the feature vector F is classifiedr＝[fr1,fr2]Is [1, 0]]When the modulation signal is 8PSK, the feature vector F is classifiedr＝[fr1,fr2]Is [0, 0]]；
Step five: according to the third power and the fourth power of raised cosine shaping function and delayed waveform to eliminate circulating cumulant interference information,
1) additional time delay delta xiiThe typical value of the system IS 1-30 us, the code element rate of the IS-95 system IS 1.288Mchip/s, the WCDMA IS 4.096Mchip/s, the CDMA2000 IS 1.2288 or 3.6864Mchip/s, and the TD-SCDMA IS 1.1136 Mchip/s; the code element period of CDMA system has reached TsLess than 1 us; on the other hand, the raised cosine shaping function is considered to meet the Nyquist criterion; when the value of the item II in the third formula, the second formula and the third formula is infinitely less than the value of the item I when the value of i is 0,1, … and Q-1, neglecting the influence of the item II in the third formula, the second formula and the third formula;
2) and 2Ts≤Δξi＜4TsWhen the attenuation parts of the raised cosine forming functions are intersected, the second term has influence on the identification accuracy in the third formula, the second formula and the third formula in the steps;
3) discussion 0 < Δ ξi＜2TsIn the time situation, the second term in the third, second and third formulas affects the identification accuracy, and the interference degree is affected by the combination of the amplitude, phase drift, delay function and raised cosine shaping function p (t) of the multipath path.
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