CN114884777B - Channel estimation method based on transform domain - Google Patents
Channel estimation method based on transform domain Download PDFInfo
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Abstract
The invention provides a method for placing pilot signals in a channel in wireless communication, which comprises the steps of obtaining pilot signals, mapping the pilot signals to a delay-Doppler domain, then transforming the pilot signals to a time-frequency domain, and obtaining transformed pilot signals; superposing the transformed pilot signal and the data signal in a time-frequency domain to obtain a superposed signal; the invention considers mapping the pilot signal to the delay Doppler domain and then transforming to the time-frequency domain to obtain a transformed pilot signal; and superposing the transformed pilot signal and the data signal in a time-frequency domain to obtain a superposed signal. Therefore, the transformed pilot signals and the data signals can be overlapped for transmission, and the transmission efficiency is improved; in addition, because the pilot signal is mapped to the delay-doppler domain and then is transformed to the time-frequency domain, the pilot signal transformed to the time-frequency domain can be uniformly dispersed in the time-frequency resource plane by utilizing the orthogonality of the delay-doppler domain and the time-frequency domain, the interference between the pilot signal and the data signal is reduced, and the transmission performance is improved.
Description
Technical Field
The present invention relates to the field of wireless communications, and more particularly, to a channel estimation method based on a transform domain in wireless communications.
Background
In a wireless communication system, due to the complex and variable conditions of a wireless channel between a transmitter and a receiver, a corresponding received signal is distorted after a wireless signal passes through the wireless channel. In order to correctly decode the signal transmitted from the transmitter, the receiver needs to perform channel estimation and compensate the received signal by the channel estimation result.
The prior technical scheme for realizing channel estimation mainly comprises the following two steps:
Scheme one: by dividing the time-frequency resources for the pilot signals, the time-frequency resources are divided into a portion for transmitting the data signals and a portion for transmitting the pilot signals, and the pilot signals are placed in the time-frequency resources for transmitting the pilot signals. However, in the first scheme, the pilot signal occupies a certain overhead, so that the actual channel transmission utilization rate is low and the transmission efficiency is low. For this, the researcher proposes a second scheme.
Scheme II: and superposing the pilot frequency signal and the data signal in a time-frequency domain, so that the time-frequency resource utilization rate is improved. And carrying out channel estimation at a receiving end in an interference elimination mode. Although the second scheme can improve the channel transmission efficiency, interference among signals is brought, and the transmission performance is reduced, so that the performance of the receiver for extracting data from the corresponding received signals is affected.
Therefore, there is a need for improvements in the art to improve transmission performance while effectively securing transmission efficiency.
Disclosure of Invention
It is therefore an object of the present invention to overcome the above-mentioned drawbacks of the prior art and to provide a method for channel estimation based on the transform domain in wireless communication.
The invention aims at realizing the following technical scheme:
According to a first aspect of the present invention, there is provided a method of placing pilot signals (or a method of placing pilot signals in wireless communication), comprising: acquiring a pilot signal, mapping the pilot signal to a delay-Doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal; and acquiring a data signal, mapping the data signal to a time-frequency domain, and superposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a superposed signal.
In some embodiments of the present invention, the transformed pilot signal and the data signal are linearly superimposed in the time-frequency domain to obtain a superimposed signal.
In some embodiments of the present invention, the pilot signal is linearly superimposed on the time slot resources occupied by the data signal, and does not occupy other time slot resources than the time slot resources occupied by the data signal.
According to a second aspect of the present invention, there is provided a method of transmitting a wireless signal, comprising: acquiring information bits, and performing code modulation on the information bits to obtain a data signal; superposing pilot signals on the data signals based on the method for placing the pilot signals in the first aspect to obtain superposed signals; the stacked signals are transmitted in the form of wireless signals.
According to a third aspect of the present invention, there is provided a channel estimation method comprising: acquiring a received signal corresponding to the wireless signal sent by the method for sending wireless signals according to the second aspect; and transforming the received signal to a delay-Doppler domain and then carrying out channel estimation to obtain a channel estimation result.
In some embodiments of the present invention, the step of transforming the received signal into the delay-doppler domain and performing channel estimation to obtain a channel estimation result includes: after the received signal is transformed to the delay-Doppler domain, detecting a pilot signal from the received signal represented by the delay-Doppler domain according to a preset detection threshold value, and obtaining an initial channel estimation result; performing channel equalization on the data signals in the received signals based on the initial channel estimation result to obtain data signals after channel equalization; subtracting the data signal and noise after channel equalization of the data signal in the received signal according to the current channel estimation result from the received signal to obtain the received signal after interference elimination; after the interference-eliminated received signal is transformed to the delay-Doppler domain, a pilot signal is detected from the interference-eliminated received signal represented by the delay-Doppler domain according to a preset detection threshold value, and a channel estimation result is obtained.
According to a fourth aspect of the present invention, there is provided a signal processing method characterized by comprising: receiving a wireless signal sent by the method for sending a wireless signal according to the second aspect, and obtaining a corresponding received signal; according to the channel estimation method and the receiving signal corresponding to the wireless signal, channel estimation is carried out on the channel for transmitting the wireless signal, and a channel estimation result is obtained; and processing the data signal in the received signal according to the channel estimation result to extract the information bit.
According to a fifth aspect of the present invention, there is provided a wireless communication method for a wireless communication system including a transmitting end and a receiving end, the wireless communication method comprising: the transmitting end obtains information bits, and codes and modulates the information bits to obtain a data signal; acquiring a pilot signal by a transmitting end, mapping the pilot signal to a delay-Doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal; the transmitting terminal acquires a data signal, maps the data signal to a time-frequency domain, and superimposes the transformed pilot signal and the data signal in the time-frequency domain to obtain a superimposed signal; the transmitting end transmits the stacked signals in the form of wireless signals; receiving the wireless signal sent by the transmitting end by the receiving end to obtain a corresponding receiving signal; the receiving end transforms the received signal to the delay Doppler domain and then carries out channel estimation to obtain a channel estimation result; and processing the data signal in the received signal by the receiving end according to the channel estimation result to extract the information bit.
According to a sixth aspect of the present invention, there is provided an electronic apparatus characterized by comprising: one or more processors; and a memory, wherein the memory is for storing executable instructions; the one or more processors are configured to implement the steps of the method of the first, second, third, fourth and/or fifth aspects via execution of the executable instructions.
Compared with the prior art, the invention has the advantages that:
The invention considers mapping the pilot signal to the delay Doppler domain and then transforming to the time-frequency domain to obtain a transformed pilot signal; and superposing the transformed pilot signal and the data signal in a time-frequency domain to obtain a superposed signal. Therefore, the transformed pilot signals and the data signals can be overlapped for transmission, and the transmission efficiency is improved; in addition, because the pilot signal is mapped to the delay-doppler domain and then is transformed to the time-frequency domain, the pilot signal transformed to the time-frequency domain can be uniformly dispersed in the time-frequency resource plane by utilizing the orthogonality of the delay-doppler domain and the time-frequency domain, the interference between the pilot signal and the data signal is reduced, and the transmission performance is improved.
Drawings
Embodiments of the invention are further described below with reference to the accompanying drawings, in which:
fig. 1 is a flow chart of a wireless communication method according to an embodiment of the invention;
Fig. 2 is a transform relationship of a delay-doppler domain and a time-frequency domain according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a pilot signal distribution in a delay-doppler domain and a time-frequency domain according to an embodiment of the present invention;
Fig. 4 is a schematic diagram of a distribution of data signals in a time-frequency domain according to an embodiment of the present invention;
Fig. 5 is a schematic diagram of signal superposition of a transformed pilot signal and a data signal in the time-frequency domain according to an embodiment of the present invention;
fig. 6 is a schematic diagram of detecting pilot signals according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a received signal for processing a wireless signal according to an embodiment of the present invention.
Detailed Description
For the purpose of making the technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail by way of specific embodiments with reference to the accompanying drawings. 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.
As mentioned in the background section, although the scheme of directly overlapping the pilot signal and the data signal in the time-frequency domain can improve the channel transmission efficiency, interference between signals is caused, and the transmission performance is reduced, so that the performance of extracting data from the corresponding received signal by the receiver is affected. Therefore, the invention considers mapping the pilot signal to the delay Doppler domain and then transforming to the time-frequency domain to obtain a transformed pilot signal; and superposing the transformed pilot signal and the data signal in a time-frequency domain to obtain a superposed signal. Therefore, the transformed pilot signals and the data signals can be overlapped for transmission, and the transmission efficiency is improved; in addition, because the pilot signal is mapped to the delay-doppler domain and then is transformed to the time-frequency domain, the pilot signal transformed to the time-frequency domain can be uniformly dispersed in the time-frequency resource plane by utilizing the orthogonality of the delay-doppler domain and the time-frequency domain, the interference between the pilot signal and the data signal is reduced, and the transmission performance is improved.
Embodiment 1:
According to one aspect of the invention, a method capable of effectively guaranteeing transmission efficiency and improving transmission performance is provided from a signal transmission layer in order to overcome the defects of the existing method. According to an embodiment of the present invention, there is provided a wireless communication system including a transmitting end and a receiving end; the wireless communication system is configured to perform a wireless communication method comprising: steps S1, S2, S3, S4, S5, S7. For a better understanding of the present invention, each step is described in detail below in connection with specific examples.
Step S1: and acquiring information bits by a transmitting end, and performing code modulation on the information bits to obtain a data signal.
According to one embodiment of the present application, the information bits refer to data to be transmitted, which is composed of 0,1 bits. The coding rule adopted for coding the information bits can be a coding rule corresponding to a Polar code, an LDPC code and/or a Turbo code, or other available coding rules, even a coding rule newly appearing after the present application, so long as the coding rule does not conflict with the principles of the present application and can still be used, and the present application is not limited in any way. The information bits are encoded to obtain codewords, and the codewords are modulated to obtain the data signal. The modulation scheme can be the existing modulation scheme such as Quadrature Amplitude Modulation (QAM), gaussian filter minimum shift key modulation (GMSK), etc., even the modulation scheme newly appeared after the application can be used as long as the modulation scheme does not conflict with the principle of the application, and the application is not limited in any way.
Step S2: and acquiring a pilot signal by a transmitting end, mapping the pilot signal to a delay-Doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal.
According to one embodiment of the present invention, the step of mapping the pilot signal to the delay-doppler domain and then transforming to the time-frequency domain comprises: mapping the pilot signal to a Delay-Doppler domain (namely, delay-Doppler domain, abbreviated as DD) by a transmitting end to obtain the pilot signal expressed in the Delay-Doppler domain; the pilot signal represented in the delay-doppler domain is transformed (THE INVERSE SYMPLECTIC FINITE Fourier transform, ISFFT) by the transmitting end to the Time-Frequency domain (i.e., time-Frequency domain, TF for short) to obtain a transformed pilot signal. Because the delay-doppler domain and the time-frequency domain have orthogonality, pilot signals transformed to the time-frequency domain are uniformly distributed on a time-frequency resource plane, interference between the pilot signals and data signals is reduced, and transmission performance is improved.
Step S3: and acquiring a data signal by a transmitting end, mapping the data signal to a time-frequency domain, and superposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a superposed signal.
According to one embodiment of the invention, the invention maps the data signal to the time-frequency domain, and then linearly superimposes the transformed pilot signal and the data signal in the time-frequency domain to obtain a superimposed signal. Namely: and acquiring a data signal, mapping the data signal to a time-frequency domain, and superposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a superposed signal. Preferably, the pilot signal is linearly superimposed on the time slot resources occupied by the data signal, and does not occupy other time slot resources than those occupied by the data signal. For example, assuming that the value of the transformed pilot signal in a certain time slot is a and the value of the data signal in the time slot is B, in the stacked signal, the value of the time slot=a+b.
Step S4: the stacked signals are transmitted in the form of wireless signals by the transmitting end.
According to one embodiment of the invention, the stacked signals are transmitted here via the antenna at the transmitting end.
Step S5: the receiving end receives the wireless signal sent by the transmitting end to obtain a corresponding receiving signal.
According to one embodiment of the present invention, a wireless signal is received by an antenna at a receiving end, and a corresponding received signal is obtained.
Step S6: and the receiving end converts the received signal to a delay-Doppler domain and then carries out channel estimation to obtain a channel estimation result.
According to one embodiment of the invention, the receiving end performs a finite octave Fourier transform (THE SYMPLECTIC FINITE Fourier transform, SFFT) on the received signal to obtain a received signal represented in the delay-Doppler domain. The channel estimation result is estimated channel parameters (some documents are also called channel state Information, CHANNEL STATE Information, abbreviated as CSI). For example, in some communication systems, channel parameters include doppler shift, time delay, and channel coefficients. It should be appreciated that in different communication systems, there may be differences in the particular types of channel parameters that need to be estimated; when detecting the pilot signal, based on the corresponding channel estimation algorithm, the corresponding channel parameters can be obtained, which is not limited in any way by the present invention.
According to one embodiment of the present invention, the step S6 includes:
S61: after the received signal is transformed to the delay-Doppler domain, detecting a pilot signal from the received signal represented by the delay-Doppler domain according to a preset detection threshold value, and obtaining an initial channel estimation result;
S62: performing channel equalization on the data signals in the received signals based on the initial channel estimation result to obtain data signals after channel equalization;
S63: subtracting the data signal and noise after channel equalization of the data signal in the received signal according to the current channel estimation result from the received signal to obtain the received signal after interference elimination; (step S63 corresponds to removing the data signal and noise effects in the received signal to better detect the pilot)
S64: after the interference-eliminated received signal is transformed to the delay-Doppler domain, a pilot signal is detected from the interference-eliminated received signal represented by the delay-Doppler domain according to a preset detection threshold value, and a channel estimation result is obtained.
Preferably, in step S64, an intermediate channel estimation result may be obtained, and steps S63 and S64 are repeated for a predetermined number of times to obtain a final channel estimation result (in the following description of the present application, the channel estimation result refers to the final channel estimation result). Therefore, iterative interference elimination is carried out to obtain a more accurate channel estimation result.
Step S7: and processing the data signal in the received signal by the receiving end according to the channel estimation result to extract the information bit.
According to one embodiment of the present application, the step of processing the data signal in the received signal according to the channel estimation result includes: and subtracting the pilot signal from the received signal, performing channel equalization by using a channel estimation result, and demodulating and decoding according to the channel equalization result to obtain information bits. It should be understood that the channel equalization, demodulation or decoding may be performed by using the existing channel equalization, demodulation or decoding techniques, or even the new way after the present application is implemented, which is not limited in any way.
The pilot placement technique and the channel estimation technique of the present application are described below in conjunction with specific examples.
First, some exemplary parameters that need to be used for this example are set as follows:
Taking an orthogonal frequency division multiplexing system (abbreviated as OFDM system) as an example, assuming that the system bandwidth of the OFDM system is b=mΔf (Hz), the duration of transmitting a single slot at a time is T f =nt, where M represents the total number of subcarriers, Δf (Hz) represents the subcarrier frequency interval, N represents the total number of OFDM symbols, one OFDM symbol contains M signals, T represents a single OFDM symbol duration period, and t=1/Δf. Therefore, the number of available resources in the time-frequency domain is MN and the number of available resources in the corresponding delay-doppler domain is MN, and each transmitted wireless signal occupies a resource grid.
The time-frequency resource plane is expressed as: Λ= { (nT, mΔf), n=0, …, N-1, m=0, …, M-1}, N, M > 0, N represents the total number of transmitted OFDM symbols, M represents the total number of subcarriers, N represents the nth OFDM symbol, M represents the mth subcarrier;
The signal in the time-frequency domain is represented as: x [ N, M ], n=0, …, N-1, m=0, …, M-1; the corresponding received signal is expressed as: y < n, m >;
The delay-doppler resource plane is expressed as: Delay interval τ=1/mΔf, doppler interval ν=1/NT, k represents the kth delay interval, l represents the ith doppler interval;
the signal of the delay-doppler domain is expressed as: x [ k, l ], k=0, …, N-1, l=0, …, M-1; the corresponding received signal is expressed as: y [ k, l ].
The delay-doppler domain impulse response of a wireless channel represents:
Where P is the number of multipaths, h i denotes the channel coefficient of the ith path, τ denotes the delay interval, τ i denotes the delay of the ith path, ν denotes the doppler interval, ν i denotes the doppler shift of the ith path, and δ (·) denotes the impulse function. Thus, complete channel information (corresponding to the channel estimation result) can be obtained by estimating the channel coefficients, delay and doppler shift of the channel.
According to the above exemplary setting parameters, the wireless signal may be represented in a time-frequency (TF) domain (corresponding to a time-frequency domain) or in a delay-Doppler (DD) domain (corresponding to a delay-Doppler domain), where the delay-Doppler domain is shown in fig. 2a, and the time-frequency domain is shown in fig. 2b, and the two domains may be transformed with each other by ISFFT and SFFT; the signal in the delay-doppler domain can be converted into a signal in the time-frequency domain by inverse finite-octave fourier transform, and the signal in the time-frequency domain can also be converted into the delay-doppler domain and the time-frequency domain by finite-octave fourier transform.
According to one example of the present invention, a wireless communication method is shown comprising steps K1, K2, K3, K4, K5, K6, K7. Wherein: step K1 corresponds to step S1 in embodiment 1; steps K2 and K3 correspond to steps S3 and S4 in embodiment 1; steps K4, K5, K6 correspond to steps S5, S6 in embodiment 1; step K7 corresponds to step S7 in embodiment 1.
K1, mapping the pilot signal in the delay-doppler domain, then through an inverse finite octave fourier transform (THE INVERSE SYMPLECTIC FINITE Fourier Transform, abbreviated ISFFT) to the time-frequency domain (corresponding time-frequency domain).
Wherein ISFFT corresponds to the formula:
Where j represents an imaginary number.
For example, as shown in FIG. 3a, the pilot signal is first transmittedMapped in the delay-doppler domain Γ. The power setting of the pilot signal is typically 20dB higher than the power of the data signal, thereby allowing for better channel estimation subsequently. Then, as shown in FIG. 3b, by inverse finite octyl Fourier transform (ISFFT) to the time-frequency domainThe 1 pilot signal occupies 1 resource grid in the delay-doppler domain, after transformation, the pilot signal of the MN time-frequency domains is obtained to occupy the whole time-frequency resource plane (when the pilot signal is sent, the energy of the pilot signal can be uniformly distributed to the whole time-frequency resource plane, and the interference of the pilot signal to the data signal can be greatly reduced when the pilot signal is overlapped compared with the prior art of directly overlapping the pilot signal and the data signal, so that the transmission performance is improved);
k2, mapping the data signal to the time-frequency domain.
For example, MN data signalsMapped to the time-frequency domain, each data signal occupies a time-frequency resource grid, as shown in fig. 4.
And K3, superposing the pilot signal (corresponding to the transformed pilot signal) of the time-frequency domain with the data signal and transmitting the superposed pilot signal.
For example, the pilot signal (corresponding to the transformed pilot signal) in the time-frequency domain shown in fig. 5a is superimposed with the data signal shown in fig. 5b, resulting in a superimposed signal shown in fig. 5c and transmitted; the corresponding formula for the stacked signals is expressed as: Wherein, Representing the transformed pilot signal(s),Representing the data signal. The TF in the upper right corner represents the time-frequency domain.
K4, receiving the wireless signal by a receiving end to obtain a corresponding receiving signal; the receiving end performs a finite octave fourier transform (THE SYMPLECTIC FiniteFourier Transform, SFFT) on the received signal (belonging to the time-frequency signal) to transform it into the delay-doppler domain. Detecting a pilot signal according to a preset judging threshold value (corresponding to a preset detecting threshold value), and performing channel estimation to obtain a channel estimation result, wherein the first time of channel estimation on a certain received signal is initial channel estimation on a data signal without subtracting channel equalization, and the subsequent time of channel estimation on a certain received signal is intermediate channel estimation or final channel estimation on the data signal without subtracting channel equalization;
the formula corresponding to SFFT is as follows:
For example, the receiver first performs a finite octave Fourier transform (SFFT) on the received signal Y [ n, m ] and transforms it to the delay-Doppler domain to obtain Y [ k, l ].
It should be appreciated that the pilot signal may be superimposed on a portion of the data signal, and thus the delay-doppler domain reception y k, l may be divided into two categories:
Where H [ k, l ] represents the channel state parameter (i.e., the channel estimate to be determined) at [ k, l ] of the delay-Doppler domain, N is Gaussian noise subject to N (0, σ 2), x d represents the data signal, x d [ k, l ] represents the data signal at [ k, l ] of the delay-Doppler domain, x p represents the pilot signal, and x p [ k, l ] represents the pilot signal at [ k, l ] of the delay-Doppler domain. It should be appreciated that the [ k, l ] of the delay-doppler domain represents the k-th delay interval and the resource block corresponding to the l-th doppler interval. When estimating the channel, the pilot signal is detected according to the discrimination threshold value. As shown in fig. 5, the data symbols after being transformed into the delay-doppler domain are regarded as data interference, and when initial channel estimation is performed, an initial discrimination threshold is generally preset to a value; when a certain received signal is subjected to channel estimation in the follow-up, the expected power of data interference and the power of additive white noise are considered in a combined mode, and the judging threshold value is dynamically adjusted. The dynamic discrimination threshold is set as Wherein SINR P represents the signal-to-interference-and-noise ratio of the pilot signal,E { } denotes the desire, x d denotes the data signal, σ 2 denotes the white noise variance, and E { x d}2＝SNRdσ2,SNRd denotes the data signal to noise ratio. The signal-to-interference-and-noise ratio of the pilot signal and the signal-to-noise ratio of the data signal can be dynamically adjusted according to the result of the previous channel estimation, so that the discrimination threshold can be correspondingly dynamically adjusted. And detecting the pilot signal according to the discrimination threshold value to obtain three parameters of Doppler shift, time delay and channel coefficient of the channel. As an illustration, after the received signal is converted from the time-frequency domain to the delay-doppler domain as shown in fig. 6a, the detected pilot signal is shown in fig. 6b (it should be understood that although only one pilot signal is shown in the corresponding diagram of fig. 3a, due to multipath effects, the receiving end receives the corresponding pilot signals at different resource blocks, e.g. 4 pilot signals as shown in fig. 6 b). It should be understood that the dynamic discrimination threshold given above is merely illustrative, and is only intended to illustrate that the channel estimation may be performed in multiple iterations to obtain a better channel estimation result, and that there are other ways of initially setting and adjusting the discrimination threshold that may be applied to the channel estimation of the present invention in the prior art, which the present invention is not limited in any way.
And K5, the receiving end performs channel equalization on the data signals according to the current channel estimation result.
K6, subtracting the additive white noise and the equalized data signal from the received signal, sequentially executing the steps K4-K6 to perform iterative interference elimination, repeating the steps for a preset number of times, and then transferring to the step K7; a schematic process of loop iteration is shown in fig. 7.
For example, the receiving end performs signal detection on the TF domain signal according to the current channel estimation result, performs interference elimination on the DD domain signal based on the signal detection result, and removes the interference of the data signal and the additive white noise on the pilot frequency; and taking the DD domain signal after interference elimination as an input signal, and iteratively executing the steps K4-K6 to obtain a more accurate channel estimation result, wherein each iteration optimizes a threshold value according to the signal-to-noise ratio of the current data signal and the signal-to-noise ratio of the pilot signal. The final channel estimation result with higher reliability can be obtained by general iteration for 2-5 rounds;
and K7, demodulating and decoding the data signal according to the finally obtained channel estimation result and the received signal.
The receiving end completes detection of the data signal according to the final channel estimation result, obtains data to be decoded, and finally decodes to obtain information bits. For example, at the receiving end, subtracting the pilot signal from the received signal according to the channel estimation result, and performing channel equalization on the obtained signal subtracted with the pilot signal to obtain a data signal after channel equalization; demodulating the data signal after channel equalization to obtain data to be decoded; and decoding the data to be decoded to obtain information bits.
Embodiment 2
According to one embodiment of the present invention, there is provided a method of placing a pilot signal, including: acquiring a pilot signal, mapping the pilot signal to a delay-doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal (the specific implementation details can refer to step S2 in embodiment 1, and details are not repeated here); the data signal is obtained, mapped to the time-frequency domain, and the transformed pilot signal and the data signal are superimposed in the time-frequency domain to obtain a superimposed signal (the specific implementation details can refer to step S3 in embodiment 1, and details are not repeated here).
Embodiment 3
According to an embodiment of the present invention, there is provided a method of transmitting a wireless signal, including: acquiring information bits, and performing code modulation on the information bits to obtain a data signal (the specific implementation details can refer to step S1 in embodiment 1, and details are not repeated here);
Acquiring a pilot signal, mapping the pilot signal to a delay-doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal (the specific implementation details can refer to step S2 in embodiment 1, and details are not repeated here); acquiring a data signal, mapping the data signal to a time-frequency domain, and superposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a superposed signal (the specific implementation details can refer to step S3 in embodiment 1, and are not repeated here); the stacked signals are transmitted in the form of wireless signals (refer to step S4 in embodiment 1 for details of implementation, and are not described here again).
Embodiment 4
According to an embodiment of the present invention, there is provided a channel estimation method including: acquiring a received signal corresponding to a wireless signal transmitted by the method of transmitting a wireless signal in embodiment 3; the received signal is transformed to the delay-doppler domain and then subjected to channel estimation to obtain a channel estimation result (the specific implementation details can refer to step S6 in embodiment 1, and details are not repeated here).
Embodiment 5
According to an embodiment of the present invention, there is provided a signal processing method including: receiving a wireless signal sent by the method for sending a wireless signal according to embodiment 3, to obtain a corresponding received signal; according to the channel estimation method and the received signal corresponding to the wireless signal in the embodiment 4, channel estimation is performed on the channel transmitting the wireless signal, so as to obtain a channel estimation result; the data signal in the received signal is processed according to the channel estimation result to extract the information bits (refer to step S7 in embodiment 1 for details of implementation, which are not described here again).
It should be noted that, although the steps are described above in a specific order, it is not meant to necessarily be performed in the specific order, and in fact, some of the steps may be performed concurrently or even in a changed order, as long as the required functions are achieved.
The present invention may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present invention.
The computer readable storage medium may be a tangible device that retains and stores instructions for use by an instruction execution device. The computer readable storage medium may include, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: portable computer disks, hard disks, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static Random Access Memory (SRAM), portable compact disk read-only memory (CD-ROM), digital Versatile Disks (DVD), memory sticks, floppy disks, mechanical coding devices, punch cards or in-groove structures such as punch cards or grooves having instructions stored thereon, and any suitable combination of the foregoing.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the technical improvements in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (7)
1. A method of channel estimation, comprising:
Acquiring a received signal corresponding to a wireless signal sent according to a preset wireless signal sending method, wherein the wireless signal sending method comprises the following steps: acquiring information bits, and performing code modulation on the information bits to obtain a data signal; superposing pilot signals on the data signals based on a preset pilot signal placing method to obtain superposed signals; transmitting the stacked signals in the form of wireless signals; the method for placing the pilot signal comprises the following steps: acquiring a pilot signal, mapping the pilot signal to a delay-Doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal; acquiring a data signal, mapping the data signal to a time-frequency domain, and superposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a superposed signal;
After transforming the received signal to the delay-doppler domain, performing channel estimation to obtain a channel estimation result, which includes:
After the received signal is transformed to the delay-Doppler domain, detecting a pilot signal from the received signal represented by the delay-Doppler domain according to a preset detection threshold value, and obtaining an initial channel estimation result;
channel equalization is performed on the data signal in the received signal based on the initial channel estimation result,
Obtaining a data signal after channel equalization;
Subtracting the data signal and noise after channel equalization of the data signal in the received signal according to the current channel estimation result from the received signal to obtain the received signal after interference elimination;
after the interference-eliminated received signal is transformed to the delay-Doppler domain, a pilot signal is detected from the interference-eliminated received signal represented by the delay-Doppler domain according to a preset detection threshold value, and a channel estimation result is obtained.
2. The channel estimation method of claim 1 wherein the transformed pilot signal and the data signal are linearly superimposed in the time-frequency domain to obtain a superimposed signal.
3. The channel estimation method according to claim 1 or 2, wherein the pilot signal is linearly superimposed on the time slot resources occupied by the data signal, and does not occupy other time slot resources than the time slot resources occupied by the data signal.
4. A signal processing method, comprising:
receiving a wireless signal sent according to a preset wireless signal sending method to obtain a corresponding receiving signal;
A channel estimation method and a received signal corresponding to a wireless signal according to one of claims 1-3, wherein the channel for transmitting the wireless signal is subjected to channel estimation to obtain a channel estimation result;
and processing the data signal in the received signal according to the channel estimation result to extract the information bit.
5. A wireless communication method for a wireless communication system including a transmitting end and a receiving end, the wireless communication method comprising:
the transmitting end obtains information bits, and codes and modulates the information bits to obtain a data signal;
Acquiring a pilot signal by a transmitting end, mapping the pilot signal to a delay-Doppler domain, and then transforming the pilot signal to a time-frequency domain to obtain a transformed pilot signal;
the transmitting terminal acquires a data signal, maps the data signal to a time-frequency domain, and superimposes the transformed pilot signal and the data signal in the time-frequency domain to obtain a superimposed signal;
the transmitting end transmits the stacked signals in the form of wireless signals;
receiving the wireless signal sent by the transmitting end by the receiving end to obtain a corresponding receiving signal;
a channel estimation method according to any one of claims 1-3, wherein the receiving end transforms the received signal to the delay-doppler domain and then performs channel estimation to obtain a channel estimation result;
and processing the data signal in the received signal by the receiving end according to the channel estimation result to extract the information bit.
6. A computer readable storage medium, having stored thereon a computer program executable by a processor to implement the steps of the method of any one of claims 1 to 5.
7. An electronic device, comprising:
One or more processors; and
A memory, wherein the memory is for storing executable instructions;
The one or more processors are configured to implement the steps of the method of any one of claims 1 to 5 via execution of the executable instructions.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110445733A (en) * | 2019-06-27 | 2019-11-12 | 熊军 | Iteration self-adapting channel denoising method and iteration self-adapting channel denoise device |
| CN112929316A (en) * | 2021-01-25 | 2021-06-08 | 南京邮电大学 | OTFS modulation-based interleaved time-frequency multiple access modulation and demodulation method and device |
| CN114026814A (en) * | 2019-06-27 | 2022-02-08 | At&T知识产权一部有限合伙公司 | Generating wireless reference signals in different domains for transmission using a collapsed time-frequency grid |
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| US7970081B2 (en) * | 2006-05-11 | 2011-06-28 | Telefonaktiebolaget Lm Ericsson (Publ) | Delay-doppler channel response demodulation method and apparatus |
| US10411843B2 (en) * | 2012-06-25 | 2019-09-10 | Cohere Technologies, Inc. | Orthogonal time frequency space communication system compatible with OFDM |
| CN105471802B (en) * | 2016-01-12 | 2018-10-16 | 上海工程技术大学 | Comb Pilot ofdm system receiver |
| CN113098819B (en) * | 2021-04-01 | 2022-11-04 | 成都星联芯通科技有限公司 | Fractional-multiple subcarrier interval frequency offset estimation method for low-orbit broadband satellite system |
| CN113395221B (en) * | 2021-04-25 | 2022-07-08 | 北京邮电大学 | Orthogonal time-frequency-space joint-based channel estimation and symbol detection method |
| CN113612709B (en) * | 2021-08-17 | 2022-05-17 | 西安电子科技大学 | Channel estimation method based on joint placement of orthogonal time-frequency-space OTFS pilot frequency |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110445733A (en) * | 2019-06-27 | 2019-11-12 | 熊军 | Iteration self-adapting channel denoising method and iteration self-adapting channel denoise device |
| CN114026814A (en) * | 2019-06-27 | 2022-02-08 | At&T知识产权一部有限合伙公司 | Generating wireless reference signals in different domains for transmission using a collapsed time-frequency grid |
| CN112929316A (en) * | 2021-01-25 | 2021-06-08 | 南京邮电大学 | OTFS modulation-based interleaved time-frequency multiple access modulation and demodulation method and device |
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