Disclosure of Invention
Aiming at the problem of high decoding complexity of an OvXDM system in the related technology, the invention provides a decoding method and a decoding device, which can reduce the decoding complexity of the OvXDM system.
The technical scheme of the invention is realized as follows:
according to an aspect of the present invention, there is provided a decoding method for an overlay multiplexing system, the decoding method comprising:
step S1, obtaining a received signal, wherein the received signal is a signal obtained by coding and modulating an input signal according to the multiplexing waveform matrix; step S2, calculating a first zero matrix according to the multiplexing waveform matrix, and carrying out minimum mean square error detection estimation on the input signal according to the received signal and the first zero matrix to obtain an initial estimation value; in step S3, the input signal is restored based on the initial estimation value.
According to one embodiment of the invention, the first zero matrix G is calculated by:
G=(HHH+σ2I)-1HH;
wherein, (.)HRepresents the conjugate transpose operation of-1Denotes the inverse operation of (-) and H denotes the multiplexed waveform matrix; sigma2Representing the noise power; i denotes an identity matrix.
According to an embodiment of the present invention, step S3 includes: calculating a second zero setting matrix corresponding to a signal to be detected in the received signals; and detecting according to the signal to be detected and the second zero setting matrix to recover the input signal corresponding to the signal to be detected.
Wherein step S3 further includes: and removing the interference signals in the received signals according to the initial estimation value so as to reserve the signals to be detected.
According to an embodiment of the present invention, the code modulating the input signal to obtain the received signal comprises the following steps: generating an envelope waveform in a modulation domain; shifting the envelope waveform in the modulation domain according to the overlapping multiplexing times to obtain a shifted envelope waveform in the modulation domain; and representing the displacement envelope waveform by using a multiplexing waveform matrix, and multiplying the multiplexing waveform matrix and the input signal to obtain a signal waveform of the input signal after coding modulation.
According to another aspect of the present invention, there is provided a decoding apparatus for an overlay multiplexing system, the decoding apparatus including the following modules connected in sequence:
the receiving module is used for acquiring a receiving signal, and the receiving signal is a signal obtained by performing coding modulation on an input signal according to the multiplexing waveform matrix; the detection estimation module is used for calculating a first zero matrix according to the multiplexing waveform matrix and carrying out minimum mean square error detection estimation on the input signal according to the received signal and the first zero matrix to obtain an initial estimation value; and the decision module recovers the input signal according to the initial estimation value.
According to one embodiment of the invention, the detection estimation module calculates the first nulling matrix G by:
G=(HHH+σ2I)-1HH;
wherein, (.)HRepresents the conjugate transpose operation of-1Denotes the inverse operation of (-) and H denotes the multiplexed waveform matrix; sigma2Representing the noise power; i denotes an identity matrix.
According to one embodiment of the invention, the decision module comprises: the calculation submodule is used for calculating a second zero setting matrix corresponding to a signal to be detected in the received signals; and the detection submodule detects according to the signal to be detected and the second zero setting matrix to recover the input signal corresponding to the signal to be detected.
Wherein, the decision module further comprises: and the interference removing submodule is used for removing the interference signals in the received signals according to the initial estimation value so as to reserve the signals to be detected.
According to an embodiment of the present invention, an encoding apparatus for code-modulating an input signal to obtain a received signal includes: an envelope waveform generating module for generating an envelope waveform in a modulation domain; the envelope waveform shifting module is used for shifting the envelope waveform in the modulation domain according to the overlapping multiplexing times to obtain a shifted envelope waveform in the modulation domain; and the coding output module is used for representing the shifting envelope waveform by using the multiplexing waveform matrix, and multiplying the multiplexing waveform matrix and the input signal to obtain a signal waveform of the input signal after coding modulation.
The invention utilizes the coding characteristic of the OvXDM system, combines the minimum mean square error-parallel interference cancellation detection, and is used for correspondingly decoding the received signal, thereby reducing the decoding complexity of the OvXDM system.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.
Fig. 1 illustrates a decoding method 100 according to an embodiment of the present invention, which can be used in an overlapping time division multiplexing system. The decoding method 100 may comprise the following steps:
step S102, acquiring a received signal, wherein the received signal is a signal obtained by performing coding modulation on an input signal according to a multiplexing waveform matrix;
step S104, calculating a first zero matrix according to the multiplexing waveform matrix, and carrying out minimum mean square error detection estimation on the input signal according to the received signal and the first zero matrix to obtain an initial estimation value;
and step S106, restoring the input signal according to the initial estimation value.
The OvXDM system may be represented as any one of an Overlapped Time Division Multiplexing (OvTDM) system, an Overlapped Frequency Division Multiplexing (OvFDM) system, an Overlapped Code Division Multiplexing (OvCDM) system, an Overlapped Space Division Multiplexing (OvSDM) system, and an Overlapped Hybrid Division Multiplexing (OvHDM) system. The OvXDM system equivalent model is shown in fig. 2.
According to one embodiment of the present invention, the first nulling matrix G may be calculated by:
G=(HHH+σ2I)-1HH;
wherein, (.)HRepresents the conjugate transpose operation of-1Denotes the inverse operation of (-) and H denotes the multiplexed waveform matrix; sigma2Representing the noise power; i denotes an identity matrix.
According to an embodiment of the invention, step S106 comprises: calculating a second zero setting matrix corresponding to a signal to be detected in the received signals; and detecting according to the signal to be detected and the second zero setting matrix to recover the input signal corresponding to the signal to be detected.
According to an embodiment of the present invention, step S106 further includes: and removing the interference signals in the received signals according to the initial estimation value so as to reserve the signals to be detected.
In order to better understand the technical scheme of the invention, the system characteristics of the OvXDM system are explained. Referring to fig. 2, first, assuming that the overlap multiplexing coefficient of the OvXDM system is K, the tap coefficients of the multiplexed waveform are defined as [ h ], respectively0,h1,…,hK-1]. In this case, according to the convolution characteristic of the superposition multiplexing relationship, if the real information bit sequence length is L and the OvXDM-encoded bit sequence is N, (N ═ L + K-1), then the multiplexed waveform can be represented in the form of a multiplexed waveform matrix H as follows:
the size of the multiplexing waveform matrix H is N × L.
Let the output vector after OvXDM system coding be Y ═ Y0,…,yN-1]TThe input vector is X ═ X0,…,xL-1]TThe encoding process of OvXDM can be expressed as Y ═ HX, i.e.:
then, at this time, the received sequence R of the received signal can be expressed as:
wherein [ n ]0,n1,…,nN-1]TIs a white noise sequence.
According to the system characteristics of the OvXDM system, the receiving end can perform corresponding decoding according to the known multiplexing waveform matrix H and the receiving sequence R.
The invention adopts a parallel interference cancellation algorithm to eliminate the interference between symbols in a parallel processing mode, recovers each input signal on the basis of the initial estimation value of the input signal X, and directly judges the signal without sequencing in the process of judging the signal. Specifically, the detection result (initial estimation value) is used to construct an interference signal estimation of a transmitted symbol, when a certain input signal is recovered, the influence of the other input signals is cancelled as interference, that is, when the kth signal is recovered, the 1 st, the 2 nd, the.
Fig. 3 shows a decoding method 200 according to an embodiment of the present invention, the decoding method 200 incorporating minimum mean square error detection, i.e. a minimum mean square error-parallel interference cancellation algorithm. Specifically, the decoding method 200 includes the following steps:
in step S202, a reception signal R and a multiplexed waveform matrix H are acquired.
Step S204, according to the received signal R and the multiplexing waveform matrix H, the input signal X is initially estimated, namely the minimum mean square error detection estimation is carried out.
According to an embodiment of the present invention, the first zero matrix G may be calculated by:
G=(HHH+σ2I)-1HH;
wherein, (.)HIndicating transpose operation in parentheses, i.e., (. cndot.) conjugate transpose operation-1Denotes the inverse operation of (-) and H denotes the multiplexed waveform matrix; sigma2Representing the noise power; i denotes an L × L identity matrix.
Then, an initial estimate of the input signal XComprises the following steps:
wherein,is an initial estimate of the kth input signal xk, where k is 1, 2.
Step S206, removing the interference signal. Received signal r after interference suppressionkThe expression of (a) is:
wherein (H)jThe j-th column is denoted by H. From the above equation, it can be seen that the received signal r after interference suppressionkIn the method, the interference signals of all other layers are removed, and only the received signal r to be detected is leftk。
Step S208, calculating a second zero matrix Gk:
Gk=(Hk HHk+σ2)-1Hk H
Step S210, wherein HkThe k-th column of the multiplexing waveform matrix H is taken, and the final detection result is as follows:
step S212, determining whether the received signal is detected. If the detection is not completed, the process returns to step S206, and the above process is repeated until all the received signals are detected. If the detection is finished, the decoding method 200 is finished.
In one embodiment, the processing procedure at the receiving end of the OvXDM system may include the following steps: step S302, preprocessing the signal received by the receiving end to obtain a preprocessed signal; step S304, carrying out signal detection on the preprocessed signals in a corresponding domain according to the minimum mean square error-parallel interference cancellation detection algorithm to obtain input information flow; wherein, the pretreatment process can comprise the following steps: and carrying out synchronization, channel estimation, equalization processing and the like on the signals received by the receiving end.
Taking the OvTDM system as an example, a receiving end processing procedure of the OvTDM system is shown in fig. 4, and specifically includes the following steps: step S402, firstly, synchronizing the received signals, including carrier synchronization, frame synchronization, symbol time synchronization and the like; and S404, correspondingly detecting the preprocessed data according to the detection algorithm.
Taking the OvFDM system as an example, the receiving end processing process is as shown in fig. 5, and specifically includes the following steps: step S502, first, fft (Fourier transform) operation is performed on the received signal to convert the time domain signal to the frequency domain; step S504, carry on the synchronization to the frequency domain signal, including carrier synchronization, frame synchronization, symbol time synchronization, etc.; and step S506, correspondingly detecting the preprocessed data according to the detection algorithm.
According to an embodiment of the present invention, code modulating the input signal to obtain the received signal may include: generating an envelope waveform in a modulation domain; shifting the envelope waveform in the modulation domain according to the overlapping multiplexing times to obtain a shifted envelope waveform in the modulation domain; and representing the displacement envelope waveform by using a multiplexing waveform matrix, and multiplying the multiplexing waveform matrix and the input signal to obtain a signal waveform of the input signal after coding modulation.
The corresponding OvXDM system coding process may comprise the following steps:
step S602, generating a complex waveform in a modulation domain according to design parameters;
step S604, shifting the envelope waveform in the modulation domain according to the overlapping multiplexing times and the preset shifting interval to obtain each shifting envelope waveform in the modulation domain;
step S606, writing the shifted envelope waveform into a matrix form, and multiplying the matrix form by a symbol in the sequence to be modulated to obtain a complex modulation envelope waveform in a modulation domain.
Taking the OvTDM system as an example, and as shown in fig. 6 and fig. 7, the specific processing steps of encoding at the transmitting end of the OvTDM system include:
in step S702, an envelope waveform h (t) of a transmission signal is designed and generated.
Step S704, shifting the envelope waveform h (T) designed in (1) by a specific time to form the envelope waveform h (T-i × Δ T) of the transmission signal at each time.
Step S706, writing the envelope waveform H (T-i × Δ T) into a matrix H form, and then multiplying the matrix H by the symbol vector x to be transmitted to form a transmitted signal waveform. Wherein, as shown in fig. 7, the overlapping multiplexing method follows the parallelogram rule.
Taking the OvFDM system as an example, and referring to fig. 8 and fig. 9, the specific processing steps of the OvFDM system transmitting end system coding include:
in step S802, a spectrum signal h (f) for generating a transmission signal is designed.
Step S804, the designed spectrum signal H (f) in (1) is shifted by a specific carrier spectrum interval Δ B, and then other subcarrier spectrum waveforms H (f-i × Δ B) with each spectrum interval Δ B are formed.
Step S806, writing the spectrum waveform H (f-i × Δ B) into a matrix H form, and then multiplying the matrix H by the symbol vector X to be transmitted, to form the spectrum S (f) of the complex modulated signal.
Step S808, performing inverse discrete fourier transform on the frequency spectrum of the complex modulation signal generated in step S806 to finally form a time domain complex modulation signal, where the transmission signal may be represented as:
Signal(t)TX=ifft(S(f))
in which, as shown in connection with fig. 9, the overlap multiplexing method follows the parallelogram rule.
The decoding method provided by the embodiment of the invention can be applied to an actual mobile communication system, and can also be widely applied to any wireless communication systems such as satellite communication, microwave line-of-sight communication, scattering communication, atmospheric optical communication, infrared communication and aquatic communication. The method can be applied to large-capacity wireless transmission and also can be applied to a small-capacity light radio system.
In summary, the decoding method of the embodiment of the present invention utilizes the coding characteristic of the OvXDM system, and combines the minimum mean square error-parallel interference cancellation detection to perform corresponding decoding on the received signal, thereby reducing the decoding complexity of the OvXDM system.
As shown in fig. 10, according to an embodiment of the present invention, there is also provided a decoding apparatus for an overlay multiplexing system, the decoding apparatus including the following modules connected in sequence:
a receiving module 1002, configured to obtain a received signal, where the received signal is obtained by performing code modulation on an input signal according to a multiplexing waveform matrix;
the detection estimation module 1004 is used for calculating a first zero matrix according to the multiplexing waveform matrix, and performing minimum mean square error detection estimation on the input signal according to the received signal and the first zero matrix to obtain an initial estimation value;
the decision module 1006 recovers the input signal according to the initial estimation value.
According to one embodiment of the invention, the detection estimation module calculates the first nulling matrix G by:
G=(HHH+σ2I)-1HH;
wherein, (.)HRepresents the conjugate transpose operation of-1Denotes the inverse operation of (-) and H denotes the multiplexed waveform matrix; sigma2Representing the noise power; i denotes an identity matrix.
According to one embodiment of the invention, the decision module 1006 includes: the calculation submodule is used for calculating a second zero setting matrix corresponding to a signal to be detected in the received signals; and the detection submodule detects according to the signal to be detected and the second zero setting matrix to recover the input signal corresponding to the signal to be detected.
According to an embodiment of the invention, the decision module 1006 further comprises: and the interference removing submodule is used for removing the interference signals in the received signals according to the initial estimation value so as to reserve the signals to be detected.
According to an embodiment of the present invention, an encoding apparatus for code-modulating an input signal to obtain a received signal includes: an envelope waveform generating module for generating an envelope waveform in a modulation domain; the envelope waveform shifting module is used for shifting the envelope waveform in the modulation domain according to the overlapping multiplexing times to obtain a shifted envelope waveform in the modulation domain; and the coding output module is used for representing the shifting envelope waveform by using the multiplexing waveform matrix, and multiplying the multiplexing waveform matrix and the input signal to obtain a signal waveform of the input signal after coding modulation.
The decoding device of the embodiment of the invention utilizes the coding characteristic of the OvXDM system and combines the minimum mean square error-parallel interference cancellation detection to correspondingly decode the received signal, thereby reducing the decoding complexity of the OvXDM system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.