CN115426234B - Millimeter wave FBMC system phase noise compensation method and application thereof - Google Patents
Millimeter wave FBMC system phase noise compensation method and application thereof Download PDFInfo
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Abstract
The invention discloses a millimeter wave FBMC system phase noise compensation method and application thereof, belonging to the technical field of wireless communication, comprising the following steps: translating symbol scattered points presented by the demodulation symbols on the complex domain graph to different degrees along the real axis direction, so as to obtain a multi-column stripe pattern on the complex domain graph, and screening the symbol scattered points on a column stripe closest to the origin; calculating virtual phase noise compensation predicted values corresponding to the screened symbol scattered points based on the slope included angles of the screened symbol scattered points and the original point connecting line, and adjusting the virtual phase noise compensation predicted values according to the deviation degree of the virtual phase noise compensation predicted values due to phase noise interference, so as to obtain phase noise compensation estimated values of demodulation symbols, so that the demodulation symbols are subjected to phase noise compensation; the method provided by the invention does not need pilot frequency, has high frequency spectrum efficiency, stronger anti-interference capability, excellent scene adaptation capability and lower error rate.
Description
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a millimeter wave FBMC system phase noise compensation method and application thereof.
Background
The continuing development of high capacity, high rate, low latency traffic demands has resulted in the inability of low frequency communications to meet these demands, and thus the beginning of focusing the eye on millimeter Wave (MILLIMETER-Wave, mmWave) communications. Millimeter wave communication has many problems to be solved as a hotspot of future communication attention, wherein Phase Noise (PN) generated by Radio Frequency (RF) front-end hardware defects may cause rotation and dispersion of a baseband symbol constellation, thereby reducing quality of a transmitter modulation signal, and may affect synchronization of a transceiver, thereby reducing accuracy of a receiver demodulation signal, thereby greatly reducing system throughput and bringing about a large Bit Error Rate (BER), and seriously affecting performance of a communication system.
The Filter Bank Multi-carrier offset quadrature amplitude modulation (FBMC) technology utilizes a prototype Filter with good time-frequency focusing characteristics to enable signals to have low side lobes and low out-of-band leakage, can set larger subcarrier spacing, has advantages in resisting PN effects, and has quite high adaptation with millimeter wave communication.
Nevertheless, the PN in the millimeter wave band still affects the millimeter wave FBMC communication system, and in addition to phase shifting the demodulated symbols, it also breaks the orthogonality of the system to generate Inter-carrier interference (Inter-CARRIER INTERFERENCE, ICI) and Inter-symbol interference (Inter Symbol Interference, ISI), so that it is necessary to deal with the PN problem in the millimeter wave FBMC communication system. The performance of the millimeter wave FBMC communication system under the influence of phase noise can be improved by applying the phase noise compensation method. The frequency domain phase noise compensation method uses constants to approximate time-varying PN, and has the advantage of small calculated amount, but because PN is changed in real time, the PN is directly approximated by the constants, errors are easy to generate, and interference is caused, so that the frequency domain phase noise compensation method is poor in effect and high in bit error rate of demodulation symbols.
Disclosure of Invention
Aiming at the defects and improvement requirements of the prior art, the invention provides a millimeter wave FBMC system phase noise compensation method and application thereof, and aims to solve the technical problem of higher bit error rate after phase noise compensation by the existing frequency domain phase noise compensation method.
To achieve the above object, in a first aspect, the present invention provides a method for compensating phase noise of a millimeter wave FBMC system, including:
S1, after receiving a sending signal which is sent by a sending end and is subjected to FBMC modulation, a receiving end carries out FBMC demodulation on a received signal to obtain an FBMC demodulation signal;
S2, respectively carrying out phase noise compensation on demodulation symbols on all subcarriers at each symbol index position in the FBMC demodulation signal;
wherein for demodulation symbols on all subcarriers at any symbol index m 0 position The method for compensating phase noise comprises the following steps:
will demodulate the symbol Translating symbol scattered points presented on the complex domain graph to different degrees along the real axis direction, so as to obtain a multi-column stripe pattern formed by the translated symbol scattered points on the complex domain graph, and screening symbol scattered points on a column stripe closest to the origin from the multi-column stripe pattern;
Based on the slope included angle between each symbol scatter point and the original point, calculating to obtain virtual phase noise compensation predicted value corresponding to each symbol scatter point, and adjusting each virtual phase noise compensation predicted value according to the deviation degree of each virtual phase noise compensation predicted value due to phase noise interference, thereby obtaining demodulation symbol Is used for compensating the estimated value of the phase noise;
Based on demodulated symbols For demodulation symbols/>, phase noise compensation estimate ofAnd compensating phase noise.
Further preferably, the symbols are demodulatedThe method for obtaining the phase noise compensation estimation value comprises the following steps:
B1, calculating the slope of the connecting line between each screened symbol scattered point and the original point, so as to obtain the slope included angle corresponding to each screened symbol scattered point;
b2, calculating to obtain virtual phase noise compensation estimated values corresponding to the screened symbol scattered points based on slope included angles corresponding to the screened symbol scattered points;
B3, calculating the deviation degree of the virtual phase noise compensation estimated value corresponding to each symbol scattered point, summing the obtained deviation degrees to obtain a demodulation symbol A severity integrated assessment value interfered by phase noise;
B4, when the comprehensive evaluation value of the severity is smaller than the preset interference threshold value, calculating the average value of the virtual phase noise compensation predicted value corresponding to each screened symbol scattered point to obtain a demodulated symbol Is used for compensating the estimated value of the phase noise; when the comprehensive evaluation value of the severity is not smaller than the preset interference threshold value, multiplying the virtual phase noise compensation predicted value corresponding to each symbol scattered point screened by the filter and the corresponding influence factor, and then summing to obtain a demodulation symbol/>Is used for compensating the estimated value of the phase noise.
Further preferably, step B3 comprises:
b31, respectively calculating the deviation between the virtual phase noise compensation predicted value corresponding to each symbol scattered point and the average value thereof, and updating the virtual phase noise compensation predicted value corresponding to each symbol scattered point into the obtained difference value;
and B32, after repeating the step B31 one or more times, calculating the sum of the virtual phase noise compensation estimated values corresponding to the scattered points of each symbol to obtain the severity comprehensive estimated value of the virtual phase noise compensation estimated value interfered by the phase noise.
Further preferably, the severity comprehensive assessment valueThe method comprises the following steps:
wherein l=0, 1, …, L-1; l is the number of the selected symbol scattered points, and the size of the L is the number K of the subcarriers; And compensating the estimated value for the virtual phase noise corresponding to the first symbol scattered point.
Further preferably, the influence factor corresponding to the virtual phase noise compensation predicted value corresponding to the first symbol scatter is:
Wherein, Is a normalized operator.
Further preferably, the method for screening the symbol scattered points on a column of stripes closest to the origin comprises:
Based on demodulated symbols The continuity of the symbol scattered points presented on the complex domain diagram takes the absolute value of the accumulated real part offset as the basis for screening the symbol scattered points, and a row of stripes with the minimum absolute value of the accumulated real part offset is taken as the stripe closest to the origin, so that the symbol scattered points on the stripes are obtained.
Further preferably, the matrix formed by symbol dispersion points obtained by shifting demodulation symbols on all subcarriers at the position of the symbol index m 0 is recorded asMatrix/>The number of lines of the sub-carriers is K, and the number of columns is S; definition of a Inclusion/>Aggregation of all elements/>Symbol scattered points in the complex domain diagram corresponding to the elements in the complex domain diagram show a regular stripe pattern due to overlapping;
the method for screening the symbol scattered points of a row of stripes closest to the origin comprises the following steps:
Matrix is formed The element with the imaginary part not less than 0 is distinguished from the element with the imaginary part not less than 0 to obtain a matrix/>, which is formed by the elements with the imaginary part not less than 0And elements with imaginary part less than 0Respectively to matrix/>And/>The elements in the matrix are ordered from small to large according to the absolute value of the imaginary part to obtain a matrix/>And/>
Respectively to a matrixAnd/>The symbol scattered points in the code pattern are screened, and the concentrated symbol scattered points in the obtained symbol scattered point set are the symbol scattered points on a row of stripes closest to the origin;
Wherein, record For/>Or/>For matrix/>The screening method comprises the following steps:
A1, initializing the last search point lambda pre to lambda 0, and initializing the accumulated real part offset d MS with the smallest absolute value and the search variable k ± to 0; wherein lambda 0 is The symbol scatter closest to the origin;
A2, calculating The k ± line element and the real part offset d R of the previous search point lambda pre are accumulated to obtain d sum＝dR+ωdMS; updating d MS to the element with the smallest absolute value in d sum; and obtain the next retrieval pointAdding lambda next to the collection/>In (a) and (b); updating the last search point lambda pre to lambda next; wherein ω is a forgetting factor, i min is an index corresponding to the element with the smallest absolute value in d sum, i min e [0,S-1];
A3, adding 1 to the value of K ±, repeating the step A2 for iteration until K ± is more than K ±-1;K± to form a matrix The number of rows of (3); at this time, set/>For matrix/>And (5) carrying out symbol scatter collection obtained after screening.
Further preferably, the transmission signal is a signal obtained by FBMC-modulating a data symbol on a transmission terminal carrier; wherein, the data symbol on the transmitting terminal carrier is a QAM symbol of S 2 order;
the i-th symbol scatter vector after translation is:
Wherein i=0, 1,..s-1; s is the number of translation times, and the value is the number of elements in an imaginary part or a real part in a QAM symbol; Demodulated symbols on all subcarriers at the position of symbol index m 0; k is the number of subcarriers; α i is a value on the imaginary or real part of the QAM symbol; 1 is the full 1 vector.
In a second aspect, the present invention provides a receiving end, configured to perform the method for compensating phase noise of the millimeter wave FBMC system provided in the first aspect of the present invention.
In a third aspect, the present invention provides a communication system comprising:
the sending end is used for sending the signal after the FBMC modulation;
And the receiving end is used for executing the millimeter wave FBMC system phase noise compensation method provided by the first aspect of the invention.
In a fourth aspect, the present invention also provides a computer readable storage medium, where the computer readable storage medium includes a stored computer program, where the computer program, when executed by a processor, controls a device where the storage medium is located to execute the method for compensating phase noise of the millimeter wave FBMC system provided in the first aspect of the present invention.
In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be obtained:
1. The invention provides a millimeter wave FBMC system phase noise compensation method, which considers the influence of interference on phase noise compensation estimation, after calculating virtual phase noise compensation predicted values corresponding to screened symbol scattered points, further endows the virtual phase noise compensation estimated values with influence factors related to the interference according to the deviation degree of the virtual phase noise compensation predicted values generated by the phase noise interference, and adjusts the virtual phase noise compensation predicted values so as to inhibit the interference influence, thereby having stronger anti-interference capability and better scene adaptability and greatly reducing the error rate.
2. According to the millimeter wave FBMC system phase noise compensation method, in the process of screening symbol scattered points, the characteristic that a continuous stripe pattern represented by a demodulation symbol before the real part of the FBMC system on a complex domain graph is influenced by phase noise and rotates is fully mined, based on the continuity of the symbol scattered points represented by the FBMC demodulation symbol on the complex domain graph, the absolute value of accumulated real part offset is used as the basis for screening the symbol scattered points, the symbol scattered point of a row of stripes closest to an original point is screened out, larger imaginary part interference can be tolerated, more effective data points are reserved, the severe condition that the pattern stripes are rotated greatly due to large phase deflection, high modulation order and the like can be adapted, the phenomenon of multiple selection and less selection is avoided, the pattern processing is more accurate, the phase noise compensation effect under a high-order modulation scene is improved, and the error rate is further reduced.
3. According to the millimeter wave FBMC system phase noise compensation method provided by the invention, the influence of phase noise interference on the virtual phase noise compensation estimated value is considered, different degrees of inhibition processing are carried out on the phase noise interference influence of different degrees, so that the final phase noise compensation effect is improved, and in the interference inhibition processing process, the deviation degree of each virtual phase noise compensation estimated value due to the phase noise interference is calculated by adopting a multi-round deviation iteration method, so that the information about the magnitude of the phase noise interference is extracted; different iteration times have different levels of information extraction capability and correspondingly generate different interference suppression effects, and the method can well suppress interference influence through multiple rounds of deviation iterative computation, and has stronger anti-interference capability and better scene adaptability.
4. Compared with the comparison method which does not need pilot frequency, the millimeter wave FBMC system phase noise compensation method provided by the invention has the advantages of better phase noise compensation effect and better bit error rate performance under the scene of high subcarrier number, high modulation order and quicker phase noise change.
Drawings
Fig. 1 is a flow chart of a low-overhead high-precision millimeter wave FBMC system phase noise compensation method provided in embodiment 1 of the present invention;
Fig. 2 is a diagram of a millimeter wave FBMC communication system model affected by phase noise according to embodiment 1 of the present invention;
FIG. 3 is a diagram of embodiment 1 of the present invention A regular stripe pattern diagram represented by symbol scattered points corresponding to elements in the pattern;
FIG. 4 is a schematic diagram of the final screening of each symbol scatter point after screening according to embodiment 1 of the present invention;
Fig. 5 is a diagram showing the comparison of bit error rates of the proposed method and the comparison method under different subcarrier numbers during 16QAM modulation according to an embodiment of the present invention;
Fig. 6 is a diagram showing comparison of bit error rates of the proposed method and the comparison method at different QAM modulation orders when k=64 according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Example 1,
A millimeter wave FBMC system phase noise compensation method, as shown in fig. 1, comprises:
S1, after receiving a sending signal which is sent by a sending end and is subjected to FBMC modulation, a receiving end carries out FBMC demodulation on a received signal to obtain an FBMC demodulation signal;
Specifically, the transmission signal is a signal obtained by performing FBMC modulation on a data symbol on a transmission terminal carrier; wherein, the data symbol on the transmitting terminal carrier is a QAM symbol of S 2 order. In an alternative embodiment, the modulation mode of the transmitting end is 64QAM, as shown in fig. 2, the data symbol on the carrier of the transmitting terminal is an 8 2 -QAM modulated signal, i.e. s=8, and the transmission signal S [ n ] at the nth time of the FBMC modulation is expressed as:
Wherein, Representing a natural number set, K representing the number of subcarriers, K representing a subcarrier index, m representing a symbol index, d k,m representing real data corresponding to the corresponding subcarrier index and the symbol index, g [ · ] representing a prototype filter function, j representing an imaginary number unit;
Demodulation symbol at time-frequency point (k 0,m0) Expressed as:
Where r n represents the signal after the transmitted signal s n has undergone the influence of channel and phase noise, Is the phase noise of the transmitting end; /(I)Phase noise at the receiving end; h [ n ] is the channel time domain response, and in this embodiment, h [ n ] =1 is assumed to pass through the undistorted ideal channel due to the concern of phase noise.
S2, respectively carrying out phase noise compensation on demodulation symbols on all subcarriers at each symbol index position in the FBMC demodulation signal;
wherein for demodulation symbols on all subcarriers at any symbol index m 0 position The method for compensating phase noise comprises the following steps:
1) Will demodulate the symbol Translating symbol scattered points presented on the complex domain graph to different degrees along the real axis direction, so as to obtain a multi-column stripe pattern formed by the translated symbol scattered points on the complex domain graph, and screening symbol scattered points on a column stripe closest to the origin from the multi-column stripe pattern;
Specifically, the i-th symbol scatter vector after translation is: Wherein i=0, 1,..s-1; s is the number of translation times, and the value is the number of elements in an imaginary part or a real part in a QAM symbol; Demodulated symbols on all subcarriers at the position of symbol index m 0; k is the number of subcarriers; α i is a value on the imaginary or real part of the QAM symbol; 1 is an all 1 vector; in particular, the method comprises the steps of, Vector formed by demodulated symbol dispersion points shifted on all subcarriers at the position of symbol index m 0, correspondingly matrix/>, formed by all shifted symbol dispersion pointsMatrix/>The number of lines of the sub-carriers is K, and the number of columns is S; definition of a Inclusion/>All element setThe symbol scattered points in the complex domain diagram corresponding to the elements in the complex domain diagram show a regular stripe pattern due to overlapping. Taking modulation scheme of 64QAM as an example, s=8, at this time/>The symbol dispersion points corresponding to the elements in the pattern are overlapped to obtain a regular stripe pattern as shown in fig. 3.
It should be noted that, there are various methods for screening out the symbol dispersion points on a row of stripes closest to the origin, and in an alternative embodiment, the screening method is as follows: setting a real part boundary and an imaginary part boundary to define a rectangle, and selecting a symbol scattered point close to an origin by a frame.
In another alternative embodiment, the screening method is: based on the continuity of symbol scattered points presented by demodulation symbols on a complex domain diagram, taking the absolute value of the accumulated real part offset as a basis for screening the symbol scattered points, and taking a row of stripes with the minimum absolute value of the accumulated real part offset as stripes closest to an origin, thereby obtaining the symbol scattered points on the stripes. In the present embodiment, the screening uses the continuity of the symbol dots in the same row of stripes. The continuity is mainly reflected on the real part of the symbol scattered points, because the imaginary parts of the symbol scattered points are influenced by the magnitude of surrounding symbol values, the unknown is achieved, the imaginary parts of the symbol scattered points are greatly different, and the real part difference is very small. Is known to beBy/>Translation along the real axis, thus/>The imaginary values of the same rows in the same. Only one scatter point in each row falls into the row of stripes closest to the origin, so that the task of screening out the symbol scatter points of the row of stripes closest to the origin can be decomposed into screening/>The most continuous scatter points of real values in each row. Since the symbol dispersion points of the row of stripes closest to the origin are to be screened, the method is first positioned at the origin, and the symbol dispersion points are screened in the positive and negative directions by using the continuity from the origin. The specific process is as follows:
First, matrix is formed The element with the imaginary part not less than 0 is distinguished from the element with the imaginary part not less than 0 to obtain a matrix/>, which is formed by the elements with the imaginary part not less than 0And elements with imaginary part less than 0Respectively to matrix/>And/>The elements in the matrix are ordered from small to large according to the absolute value of the imaginary part to obtain a matrix/>And/>
In particular, the method comprises the steps of,Superscript + denotes a portion having an imaginary part not less than 0, and superscript-denotes a portion having an imaginary part less than 0; /(I)And/>Is the two matrices after the distinction, K + and K - represent the number of rows of the two matrices, K + XS and K - XS represent the dimensions of the two matrices, respectively; according to the absolute value of the imaginary part value, pair/>And/>The elements in the elements are ordered from small to large to obtain
Second, respectively to matrixAnd/>The symbol scattered points in the code pattern are screened, and the concentrated symbol scattered points in the obtained symbol scattered point set are the symbol scattered points on a row of stripes closest to the origin;
Specifically, note For/>Or/>For matrix/>The screening method comprises the following steps:
A1, initializing the last search point lambda pre to lambda 0, and initializing the accumulated real part offset d MS with the smallest absolute value and the search variable k ± to 0; wherein lambda 0 is The symbol scatter closest to the origin;
A2, calculating Real part offset/>, of the k ± th line element and the last search point lambda pre (Wherein,/>For matrix/>Vector formed by elements in the k ± th line) and accumulating the real part offset to obtain d sum＝dR+ωdMS＝[dsum,0,dsum,1,...,dsum,S-1 ], wherein ω is a forgetting factor, and the value in the embodiment is 0.7; updating d MS to the element with the smallest absolute value in d sum, i.e./>Wherein i min is the index corresponding to the element with the smallest absolute value in d sum, i min epsilon [0,S-1]; and taking the symbol scatter point corresponding to the smallest absolute value of the accumulated real part offset in the current k ± row as the next retrieval point, namely/>Adding lambda next to the collection/>In (a) and (b); updating the last search point lambda pre to lambda next;
A3, adding 1 to the value of K ±, repeating the step A2 for iteration until K ± is more than K ±-1;K± to form a matrix The number of rows of (3); at this time, set/>For matrix/>And (5) carrying out symbol scatter collection obtained after screening.
Specifically, the final selected symbol scattered points after the screening is shown in fig. 4.
The invention fully digs the characteristic that the demodulation symbol before taking the real part of the FBMC system rotates under the influence of the phase noise, screens the symbol scattered points of the demodulation symbol after being influenced by the phase noise on the pattern presented on the complex domain diagram, takes the absolute value of the accumulated real part offset as the basis of screening the symbol scattered points based on the continuity of the symbol scattered points presented on the complex domain diagram by the FBMC demodulation symbol, screens the symbol scattered points of a row of stripes closest to the origin, can tolerate larger imaginary part interference, reserves more effective data points, is a more accurate symbol scattered point screening method, can adapt to the bad condition that the pattern stripes rotate greatly due to large phase deflection, high modulation order and the like, avoids the occurrence of multiple selection and less selection phenomena, processes the pattern more accurately, ensures that the effect of phase noise compensation under a high-order modulation scene is improved, and further reduces the error rate.
2) Based on the slope included angle between each symbol scatter point and the original point, calculating to obtain virtual phase noise compensation predicted value corresponding to each symbol scatter point, and adjusting each virtual phase noise compensation predicted value according to the deviation degree of each virtual phase noise compensation predicted value due to phase noise interference, thereby obtaining demodulation symbolIs used for compensating the estimated value of the phase noise;
Specifically, the symbols are demodulated The method for obtaining the phase noise compensation estimation value comprises the following steps:
B1, calculating the slope of the connecting line between each screened symbol scattered point and the original point, so as to obtain the slope included angle corresponding to each screened symbol scattered point;
Specifically, the selected symbol scattered point sets are recorded as Wherein the first element/>The slope of the straight line connected with the corresponding symbol scattered point and the origin point is as follows: /(I)According toFind the corresponding slope included angle/>So that the slope included angle corresponding to each symbol scattered point is selectedThe size of the number L of the symbol scattered points to be screened is equal to the number K of the subcarriers.
B2, calculating to obtain virtual phase noise compensation estimated values corresponding to the screened symbol scattered points based on slope included angles corresponding to the screened symbol scattered points;
specifically, the virtual phase noise compensation predicted value corresponding to the first symbol scatter is:
Correspondingly, the virtual phase noise compensation predicted value corresponding to each symbol scatter point is:
B3, calculating the deviation degree of the virtual phase noise compensation estimated value corresponding to each symbol scattered point, summing the obtained deviation degrees to obtain a demodulation symbol A severity integrated assessment value interfered by phase noise;
specifically, the step B3 includes the following steps:
B31, respectively calculating the deviation between the virtual phase noise compensation predicted value corresponding to each symbol scattered point and the average value thereof, and updating the virtual phase noise compensation predicted value corresponding to each symbol scattered point into the obtained difference value;
and B32, after repeating the step B31 one or more times, calculating the sum of the virtual phase noise compensation estimated values corresponding to the scattered points of each symbol to obtain the severity comprehensive estimated value of the virtual phase noise compensation estimated value interfered by the phase noise.
In an alternative embodiment, step B31 is repeated twice, at which time the severity is assessed comprehensivelyThe calculation process of (2) is as follows:
wherein l=0, 1, …, L-1; l is the number of the selected symbol scattered points, and the size of the L is the number K of the subcarriers; And compensating the estimated value for the virtual phase noise corresponding to the first symbol scattered point.
B4, when the comprehensive evaluation value of the severity is smaller than the preset interference threshold value, calculating the average value of the virtual phase noise compensation predicted value corresponding to each screened symbol scattered point to obtain a demodulated symbolIn the phase noise compensation estimation value of (1), at this time, the demodulation symbol/>Phase noise compensation estimate/>
When the comprehensive evaluation value of the severity is not less than the preset interference threshold value, multiplying the virtual phase noise compensation predicted value corresponding to each symbol scattered point screened by the filter with the corresponding influence factor and then summing to obtain a demodulated symbolIn the phase noise compensation estimation value of (1), at this time, the demodulation symbol/>Phase noise compensation estimate/>In this embodiment, the preset interference threshold value is 10 -4.
Specifically, ζ is an influence factor associated with interference, and is obtained through logarithmic operation and normalization processing, specifically:
Wherein, Is a normalized operator; the virtual phase noise compensation estimated value corresponding to the first symbol scattered point corresponds to the influence factor:
It should be noted that the number of the substrates, Difference from the mean value/>The closer the mean value of the difference from the mean value isThe more likely the correct data is, the higher/>Pair/>Is a function of (a) and (b). From the theory of information, the information quantity and the reference object show an exponential relation, and the probability and the numerical expression of the information quantity show a logarithmic relation. /(I)The greater the interference experienced, the gap/>At the gap sum/>The larger the duty cycle of (a) corresponds to/>The smaller the probability of occurrence, the probability is converted to/>, by logarithmic function and normalizationPair/>Numerical expression of influencing factors of/>Pair/>The smaller the influence factor should be, thereby achieving the purpose of suppressing interference. The invention considers/>The information value of the medium elements is extracted through logarithmic operation; the method has infinite relation with the base number of the logarithmic operation, so that the comprehensive processing idea of the method of the embodiment is embodied only by the logarithmic operation.
The invention carries out the interference suppression processing of evaluation synthesis on the virtual phase noise compensation predicted value corresponding to each symbol scattered point; obtaining the estimated interference severity by using the difference between the estimates of the virtual phase noise compensation of the symbol scattered points; and according to the interference severity, carrying out different comprehensive processing on the virtual phase noise compensation predicted value of the symbol scattered point, thereby obtaining a demodulation symbolIs used for compensating the estimated value of the phase noise. Through interference suppression processing, the phase noise compensation method has stronger anti-interference capability.
3) Based on demodulated symbolsFor demodulation symbols/>, phase noise compensation estimate ofAnd compensating phase noise.
In particular, demodulation of symbols is utilizedPhase noise compensation estimate/>For demodulation symbols/>Performing phase noise compensation to obtain demodulation symbols after phase noise compensation, wherein the demodulation symbols are as follows: /(I)
It should be noted that, the demodulation symbols on all subcarriers at each symbol index position in the FBMC demodulation signal are subjected to phase noise compensation by the above method.
Fig. 5 is a bit error rate diagram of the proposed method and the comparison method for different numbers of subcarriers in 16QAM modulation according to this embodiment. As can be seen from the graph, the BER of the method according to the embodiment of the present invention is lower than that of the comparison method under the conditions that the number of subcarriers k=64, k=128 and k=256. Fig. 6 is a diagram of bit error rates of the proposed method and the comparison method for different QAM modulation orders when the number of subcarriers k=64 according to an embodiment of the present invention. As can be seen from the graph, under the conditions of 16QAM, 64QAM and 256QAM, the BER of the method provided by the invention is lower than that of a comparison method, so that the phase noise compensation method provided by the invention has better phase noise compensation effect and better bit error rate performance.
In summary, in the phase noise compensation method of the frequency domain class, the characteristic that the demodulation symbol before the real part of the FBMC system presents a continuous stripe pattern on the complex domain diagram and rotates under the influence of the phase noise is worth fully mining and utilizing. Therefore, the embodiment provides an anti-interference high-adaptability blind phase noise compensation method for an FBMC system, which solves the technical problems of lower error rate performance after phase noise compensation caused by insufficient utilization of the characteristics of the FBMC communication system and no interference influence is considered in the existing frequency domain phase noise compensation method by carrying out more accurate symbol scatter screening on a pattern presented by a demodulation symbol on a complex domain diagram and combining with interference suppression processing, so that the phase noise compensation method has stronger anti-interference capability, better scene adaptation capability and better error rate performance. In addition, the method provided by the invention does not need pilot frequency, has high frequency spectrum efficiency, and has better phase noise compensation effect and better error rate performance under severe scenes with larger interference such as high subcarrier number, high modulation order, quicker phase noise change and the like compared with the comparison method which does not need pilot frequency.
EXAMPLE 2,
A receiving end is configured to perform the method for compensating phase noise of the millimeter wave FBMC system provided in embodiment 1 of the present invention.
Further, in an alternative embodiment, the receiving end includes: the millimeter wave FBMC system phase noise compensation method provided by the embodiment 1 of the invention is implemented by a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program.
The related technical solution is the same as that of embodiment 1, and will not be described here in detail.
EXAMPLE 3,
A communication system, comprising:
the sending end is used for sending the signal after the FBMC modulation;
The receiving end is configured to execute the millimeter wave FBMC system phase noise compensation method provided in embodiment 1 of the present invention.
The related technical solution is the same as that of embodiment 1, and will not be described here in detail.
EXAMPLE 4,
A computer readable storage medium comprising a stored computer program, wherein the computer program, when executed by a processor, controls a device in which the storage medium resides to execute the millimeter wave FBMC system phase noise compensation method provided in embodiment 1 of the present invention.
The related technical solution is the same as that of embodiment 1, and will not be described here in detail.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The millimeter wave FBMC system phase noise compensation method is characterized by comprising the following steps:
S1, after receiving a sending signal which is sent by a sending end and is subjected to FBMC modulation, a receiving end carries out FBMC demodulation on a received signal to obtain an FBMC demodulation signal;
S2, respectively carrying out phase noise compensation on demodulation symbols on all subcarriers at each symbol index position in the FBMC demodulation signal;
wherein for demodulation symbols on all subcarriers at any symbol index m 0 position The method for compensating phase noise comprises the following steps:
demodulating the symbol Translating symbol scattered points presented on the complex domain graph to different degrees along the real axis direction, so as to obtain a multi-column stripe pattern formed by the translated symbol scattered points on the complex domain graph, and screening symbol scattered points on a column stripe closest to the origin from the multi-column stripe pattern;
Calculating virtual phase noise compensation predicted values corresponding to the screened symbol scattered points based on the slope included angle of the screened symbol scattered points and the origin connecting line, and adjusting the virtual phase noise compensation predicted values according to the deviation degree of the virtual phase noise compensation predicted values due to phase noise interference, thereby obtaining the demodulation symbol Is used for compensating the estimated value of the phase noise;
Based on the demodulated symbols Phase noise compensation estimate of (c) for the demodulated symbol/>And compensating phase noise.
2. The method for compensating for phase noise of millimeter wave FBMC system according to claim 1, characterized in that the demodulation symbolThe method for obtaining the phase noise compensation estimation value comprises the following steps:
B1, calculating the slope of the connecting line between each screened symbol scattered point and the original point, so as to obtain the slope included angle corresponding to each screened symbol scattered point;
B2, calculating to obtain virtual phase noise compensation predicted values corresponding to the screened symbol scattered points based on slope included angles corresponding to the screened symbol scattered points;
B3, calculating the deviation degree of the virtual phase noise compensation estimated value corresponding to each symbol scattered point selected by the selection and the phase noise interference, and summing the obtained deviation degrees to obtain the demodulation symbol A severity integrated assessment value interfered by phase noise;
B4, when the severity comprehensive evaluation value is smaller than a preset interference threshold value, calculating the average value of virtual phase noise compensation predicted values corresponding to the screened symbol scattered points to obtain the demodulation symbol Is used for compensating the estimated value of the phase noise; when the severity comprehensive evaluation value is not smaller than a preset interference threshold value, multiplying the virtual phase noise compensation predicted value corresponding to each screened symbol scattered point by the corresponding influence factor and then summing to obtain the demodulation symbol/>Is used for compensating the estimated value of the phase noise.
3. The method for compensating phase noise of millimeter wave FBMC system according to claim 2, characterized in that the step B3 comprises:
b31, respectively calculating the deviation between the virtual phase noise compensation predicted value corresponding to each symbol scattered point and the average value thereof, and updating the virtual phase noise compensation predicted value corresponding to each symbol scattered point into the obtained difference value;
and B32, after repeating the step B31 one or more times, calculating the sum of the virtual phase noise compensation estimated values corresponding to the scattered points of each symbol to obtain the severity comprehensive estimated value of the virtual phase noise compensation estimated value interfered by the phase noise.
4. The method for compensating for phase noise of millimeter wave FBMC system according to claim 3, characterized in that the severity integrated evaluation valueThe method comprises the following steps:
wherein l=0, 1, …, L-1; l is the number of the selected symbol scattered points, and the size of the L is the number K of the subcarriers; And compensating the estimated value for the virtual phase noise corresponding to the first symbol scattered point.
5. The method for compensating phase noise of millimeter wave FBMC system according to claim 2, characterized in that the virtual phase noise compensation estimated value corresponding to the first symbol dispersion point corresponds to the influence factor as follows:
Wherein, Is a normalized operator.
6. The method for compensating phase noise of millimeter wave FBMC system according to any one of claims 1-5, characterized in that the method for screening symbol dispersion points on the column of stripes closest to the origin comprises:
Based on the demodulated symbols The continuity of the symbol scattered points presented on the complex domain diagram takes the absolute value of the accumulated real part offset as the basis for screening the symbol scattered points, and a row of stripes with the minimum absolute value of the accumulated real part offset is taken as the stripe closest to the origin, so that the symbol scattered points on the stripes are obtained.
7. The method for compensating phase noise of millimeter wave FBMC system according to claim 6 wherein the matrix formed by symbol dispersion points after shifting demodulation symbols on all subcarriers at the position of symbol index m 0 is recorded asMatrix/>The number of lines of the sub-carriers is K, and the number of columns is S; definition of a Inclusion/>All element set Symbol scattered points in the complex domain diagram corresponding to the elements in the complex domain diagram show a regular stripe pattern due to overlapping;
the method for screening the symbol scattered points on the row of stripes closest to the origin comprises the following steps:
Matrix is formed The element with the imaginary part not less than 0 is distinguished from the element with the imaginary part not less than 0 to obtain a matrix/>, which is formed by the elements with the imaginary part not less than 0And elements with imaginary part less than 0Respectively to matrix/>And/>The elements in the matrix are ordered from small to large according to the absolute value of the imaginary part to obtain a matrix/>And/>
Respectively to a matrixAnd/>The symbol scattered points in the code pattern are screened, and the concentrated symbol scattered points in the obtained symbol scattered point set are the symbol scattered points on a row of stripes closest to the origin;
Wherein, record For/>Or/>For matrix/>The screening method comprises the following steps:
A1, initializing the last search point lambda pre to lambda 0, and initializing the accumulated real part offset d MS with the smallest absolute value and the search variable k ± to 0; lambda 0 is The symbol scatter closest to the origin; /(I)
A2, calculatingThe k ± line element and the real part offset d R of the previous search point lambda pre are accumulated to obtain d sum＝dR+ωdMS; updating d MS to the element with the smallest absolute value in d sum; and obtain the next retrieval pointAdding lambda next to the collection/>In (a) and (b); updating the last search point lambda pre to lambda next; wherein ω is a forgetting factor, i min is an index corresponding to the element with the smallest absolute value in d sum, i min e [0,S-1];
A3, adding 1 to the value of K ±, repeating the step A2 for iteration until K ± is more than K ±-1;K± to form a matrix The number of rows of (3); at this time, set/>For matrix/>And (5) carrying out symbol scatter collection obtained after screening.
8. A receiving end, configured to perform the method for compensating phase noise of the mmwave FBMC system according to any one of claims 1-7.
9. A communication system, comprising:
the sending end is used for sending the signal after the FBMC modulation;
a receiving end, configured to perform the millimeter wave FBMC system phase noise compensation method according to any one of claims 1 to 7.
10. A computer readable storage medium, characterized in that the computer readable storage medium comprises a stored computer program, wherein the computer program, when run by a processor, controls a device in which the storage medium is located to perform the millimeter wave FBMC system phase noise compensation method according to any one of claims 1-7.
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