CN114884777A - Channel estimation method based on transform domain - Google Patents
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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, and then transforming the time-frequency domain to obtain 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 that the pilot signal is mapped to a time delay Doppler domain and then transformed to a 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 converted pilot signal and the data signal can be superposed together for transmission, and the transmission efficiency is improved; in addition, because the pilot signal is mapped to the delay Doppler domain and then transformed to the time-frequency domain, the pilot signal transformed to the time-frequency domain is uniformly dispersed on a time-frequency resource plane by utilizing the orthogonality of the delay Doppler domain and the time-frequency domain, so that 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 communication, in particular to the field of channel estimation in wireless communication, and more particularly to a transform domain-based channel estimation method in wireless communication.
Background
In a wireless communication system, due to the fact that the conditions of a wireless channel between a transmitter and a receiver are complex and changeable, the wireless signal can cause distortion of a corresponding received signal after passing through the wireless channel. In order to correctly decode the signal transmitted by the transmitter, the receiver needs to perform channel estimation and compensate the received signal by the channel estimation result.
The existing technical solutions for implementing channel estimation mainly include the following two types:
the first scheme is as follows: the pilot signal is placed in the time frequency resource for transmitting the pilot signal by dividing the time frequency resource for the pilot signal into a part for transmitting the data signal and a part for transmitting the pilot signal. However, in the first scheme, since the pilot signal occupies a certain overhead, the actual channel transmission utilization rate is low, and the transmission efficiency is not high. Therefore, the researchers propose a second scheme.
Scheme II: the pilot signal and the data signal are overlapped in a time-frequency domain, and the utilization rate of time-frequency resources is improved. And performing 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 influenced.
Therefore, there is a need for improvement of the prior art to improve transmission performance while effectively guaranteeing transmission efficiency.
Disclosure of Invention
Accordingly, the present invention is directed to overcoming the above-mentioned shortcomings of the prior art and providing a transform domain based channel estimation method in wireless communication.
The purpose of the invention is realized by 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 resource occupied by the data signal, and does not occupy other time slot resources than the time slot resource 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 coding modulation on the information bits to obtain data signals; superimposing a pilot signal on the data signal based on the method for placing a pilot signal according to the first aspect to obtain a superimposed signal; the superimposed signal is transmitted in the form of a wireless signal.
According to a third aspect of the present invention, there is provided a channel estimation method, comprising: acquiring a receiving signal corresponding to a wireless signal transmitted by the method for transmitting a wireless signal according to the second aspect; and converting the received signal into a delay Doppler domain, and then performing channel estimation to obtain a channel estimation result.
In some embodiments of the present invention, the step of performing channel estimation after transforming the received signal into the delay-doppler domain to obtain a channel estimation result includes: after converting the received signal to a delay-Doppler domain, detecting a pilot signal from the received signal represented by the delay-Doppler domain according to a preset detection threshold value to obtain an initial channel estimation result; performing channel equalization on the data signal in the received signal based on the initial channel estimation result to obtain a data signal after the channel equalization; subtracting a data signal and noise obtained by performing channel equalization on a data signal in the received signal according to a current channel estimation result from the received signal to obtain a received signal subjected to interference cancellation; and after the received signal after the interference elimination is converted into a delay Doppler domain, detecting a pilot signal from the received signal after the interference elimination represented by the delay Doppler domain according to a preset detection threshold value to obtain a channel estimation result.
According to a fourth aspect of the present invention, there is provided a signal processing method comprising: receiving a wireless signal sent by the method for sending a wireless signal according to the second aspect to obtain a corresponding received signal; performing channel estimation on a channel transmitting the wireless signal according to the channel estimation method and a received signal corresponding to the wireless signal in the third aspect 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.
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: acquiring information bits by a transmitting terminal, and carrying out coding modulation on the information bits to obtain data signals; acquiring a pilot signal by a transmitting terminal, 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 by a transmitting terminal, 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; transmitting the superposed signals in the form of wireless signals by a transmitting terminal; receiving the wireless signal sent by the transmitting terminal by the receiving terminal to obtain a corresponding received signal; converting the received signal to a delay Doppler domain by a receiving end and then carrying 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 so as to extract the information bit.
According to a sixth aspect of the present invention, there is provided an electronic apparatus, comprising: one or more processors; and a memory, wherein the memory is to store executable instructions; the one or more processors are configured to implement the steps of the methods 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 that the pilot signal is mapped to a time delay Doppler domain and then transformed to a 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 converted pilot signal and the data signal can be superposed together for transmission, and the transmission efficiency is improved; in addition, because the pilot signal is mapped to the delay Doppler domain and then transformed to the time-frequency domain, the pilot signal transformed to the time-frequency domain is uniformly dispersed on a time-frequency resource plane by utilizing the orthogonality of the delay Doppler domain and the time-frequency domain, so that 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 illustrating a wireless communication method according to an embodiment of the invention;
FIG. 2 is a diagram illustrating a transformation relationship between a time delay-Doppler domain and a time-frequency domain according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating the distribution of pilot signals in the time-delay-Doppler domain and the time-frequency domain according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating 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 diagram illustrating a detected pilot signal according to an embodiment of the invention;
fig. 7 is a schematic diagram of processing a received signal of a wireless signal according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail by embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As mentioned in the background section, although the scheme of directly stacking the pilot signal and the data signal in the time-frequency domain can improve the channel transmission efficiency, interference between signals is brought, the transmission performance is reduced, and the performance of the receiver for extracting data from the corresponding received signal is affected. Therefore, the invention considers that the pilot signal is mapped to the time delay Doppler domain and then transformed to the time frequency domain to obtain the 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 converted pilot signal and the data signal can be superposed together for transmission, and the transmission efficiency is improved; in addition, because the pilot signal is mapped to the delay Doppler domain and then transformed to the time-frequency domain, the pilot signal transformed to the time-frequency domain is uniformly dispersed on a time-frequency resource plane by utilizing the orthogonality of the delay Doppler domain and the time-frequency domain, so that 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, aiming at the defects of the current existing method, a method capable of effectively guaranteeing the transmission efficiency and simultaneously improving the transmission performance is provided from the signaling aspect. 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 including: steps S1, S2, S3, S4, S5, S5, S7. For a better understanding of the present invention, each step is described in detail below with reference to specific examples.
Step S1: and acquiring the information bits by the transmitting terminal, and coding and modulating the information bits to obtain the data signal.
According to one embodiment of the present invention, the information bits refer to data to be transmitted consisting of 0, 1 bits. The coding rule used for coding the information bits may be a coding rule corresponding to Polar code, LDPC code and/or Turbo code, or other available coding rules, even a coding rule newly appeared after the present application may still be used as long as it is not in conflict with the principle of the present invention, and the present invention does not limit this. And coding the information bits to obtain a code word, and modulating the code word to obtain a data signal. The modulation mode may be an existing modulation mode such as Quadrature Amplitude Modulation (QAM) and gaussian filter minimum shift keying (GMSK), or even a modulation mode newly appearing after the present application, and the present invention may still be used as long as the modulation mode does not conflict with the principle of the present invention, and the present invention does not impose any limitation on this.
Step S2: and acquiring a pilot signal by the transmitting terminal, mapping the pilot signal to a delay Doppler domain, and then transforming the delay Doppler domain to a time-frequency domain to obtain a transformed pilot signal.
According to an embodiment of the present invention, the step of mapping the pilot signal to the delay-doppler domain and then transforming the pilot signal to the time-frequency domain comprises: mapping the pilot signal to a Delay-Doppler domain (namely, a Delay-Doppler domain, which is abbreviated as DD) by a transmitting terminal to obtain the pilot signal represented in the Delay-Doppler domain; the transmitting end transforms The pilot signal represented in The delay-doppler domain to The Time-Frequency domain (i.e., Time-Frequency domain, abbreviated as TF) through Inverse Finite Fourier transform (ISFFT), so as to obtain a transformed pilot signal. Because the time delay Doppler domain and the time frequency domain have orthogonality, the pilot signals transformed to the time frequency domain can be uniformly distributed on a time frequency resource plane, so that the interference between the pilot signals and the data signals is reduced, and the transmission performance is improved.
Step S3: and acquiring a data signal by a transmitting terminal, 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 present invention, the data signal is mapped to the time-frequency domain, and then the transformed pilot signal and the data signal are linearly superimposed 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 resource occupied by the data signal, and does not occupy other time slot resources except the time slot resource 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, the value of the time slot is a + B in the superimposed signal.
Step S4: the superposed signals are transmitted by the transmitting end in the form of wireless signals.
According to one embodiment of the invention, the superposed signals are transmitted here via an antenna at the transmitting end.
Step S5: and the receiving end receives the wireless signal sent by the transmitting end to obtain a corresponding received signal.
According to an embodiment of the present invention, the wireless signal is received by an antenna at the receiving end, and a corresponding received signal is obtained.
Step S6: and the receiving end transforms the received signal to a delay Doppler domain and then carries out channel estimation to obtain a channel estimation result.
According to an embodiment of The present invention, The receiving end performs a Finite Fourier transform (SFFT) on The received signal, so as to obtain The received signal represented in The delay-doppler domain. The Channel estimation result is the estimated Channel parameters (some documents are also called Channel State Information, CSI for short). For example, in some communication systems, the channel parameters include doppler shift, time delay, and channel coefficients. It should be understood that in different communication systems, the specific types of channel parameters that need to be estimated may differ; when detecting the pilot signal, the corresponding channel parameters may be obtained based on the corresponding channel estimation algorithm, which is not limited in the present invention.
According to an embodiment of the present invention, the step S6 includes:
s61: after converting the received signal to a delay-Doppler domain, detecting a pilot signal from the received signal represented by the delay-Doppler domain according to a preset detection threshold value to obtain an initial channel estimation result;
s62: performing channel equalization on the data signal in the received signal based on the initial channel estimation result to obtain a data signal after the channel equalization;
s63: subtracting a data signal and noise obtained by performing channel equalization on a data signal in the received signal according to a current channel estimation result from the received signal to obtain a received signal subjected to interference cancellation; (step S63 is equivalent to removing the data signal and noise effects in the received signal to better detect the pilot)
S64: and after the received signal after the interference elimination is converted into a delay Doppler domain, detecting a pilot signal from the received signal after the interference elimination represented by the delay Doppler domain according to a preset detection threshold value to obtain a channel estimation result.
Preferably, in step S64, the obtained result may be an intermediate channel estimation result, and after the steps S63 and S64 are repeated for a predetermined number of times, a final channel estimation result is obtained (in the following description of the present application, the channel estimation result refers to a 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 so as to extract the information bit.
According to an embodiment of the present invention, the 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 performing demodulation and decoding according to the channel equalization result to obtain the information bit. It should be understood that the channel equalization, demodulation, or decoding method can be implemented by using the existing channel equalization, demodulation, or decoding technology, and even newly appeared after the present application, and the present invention is not limited thereto.
The techniques for pilot placement and channel estimation of the present application are described below with reference to specific examples.
First, some exemplary parameter settings that may be needed for this example are as follows:
by orthogonal frequency division multiplexingTaking a system (OFDM system for short) as an example, assuming that the system bandwidth of the OFDM system is B ═ M Δ f (hz), and the duration of one transmission time slot is T f NT, where M denotes the total number of subcarriers, Δ f (hz) denotes the subcarrier frequency spacing, N denotes the total number of OFDM symbols, one OFDM symbol contains M signals, T denotes a single OFDM symbol duration period, and T1/Δ f. 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 MN, and each transmitted wireless signal occupies one resource grid.
The time-frequency resource plane is represented as: Λ { (nT, M Δ f), N { (0, …, N-1, M { (0, …, M-1}, N, M > 0, N denotes the total number of transmitted OFDM symbols, M denotes the total number of subcarriers, N denotes the nth OFDM symbol, and M denotes 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 represented as: y [ n, m ];
the delay-doppler resource plane is represented as:
the time delay interval tau is 1/M delta f, the Doppler interval v is 1/NT, k represents the kth time delay interval, and l represents the lth Doppler interval;
the signal in the delay-doppler domain is represented as: x [ k, l ], k ═ 0, …, N-1, l ═ 0, …, M-1; the corresponding received signal is represented as: y [ k, l ].
The time delay-Doppler domain impulse response of the wireless channel is represented as:
where P is the number of multipaths, h i Denotes the channel coefficient of the ith path, τ denotes the delay interval, τ i Time delay of ith path, v Doppler interval, v i Represents the doppler shift of the ith path, and δ (·) represents the impulse function. Therefore, complete channel information (corresponding to a channel estimation result) can be obtained by estimating channel coefficients, time 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, the time-frequency domain is shown in fig. 2b, and the two domains may be transformed by ISFFT and SFFT; the signal of the delay-doppler domain can be converted into a signal of a time-frequency domain through inverse finite symplectic fourier transform, and the signal of the time-frequency domain can also be converted into the delay-doppler domain and the time-frequency domain through finite symplectic fourier transform.
According to an example of the invention, a wireless communication method is shown comprising the steps K1, K2, K3, K4, K5, K6, K7. Wherein: step K1 corresponds to step S1 in embodiment 1; steps K2, K3 correspond to steps S3, S4 in embodiment 1; steps K4, K5, and K6 correspond to steps S5 and S6 in embodiment 1; step K7 corresponds to step S7 in embodiment 1.
K1, mapping The pilot signal in The delay-doppler domain, and then transforming The signal to The time-frequency domain (corresponding to The time-frequency domain) by Inverse Finite Fourier Transform (ISFFT).
The formula corresponding to the ISFFT is as follows:
For example, as shown in FIG. 3a, the pilot signal is first transmitted
Mapped 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 better subsequent channel estimation. Then, as shown in FIG. 3b, by inverse finite symplectic Fourier transform (ISFFT) to the time-frequency domain
Here 1 pilot signalThe time delay Doppler domain occupies 1 resource grid, pilot signals of MN time frequency domains obtained after transformation occupy the whole time frequency resource plane (when the pilot signals are sent, the energy of the pilot signals can be uniformly distributed to the whole time frequency resource plane, and the interference of the pilot signals to data signals during superposition can be greatly reduced compared with the prior art that the pilot signals and the data signals are directly superposed, so that the transmission performance is improved);
k2, mapping the data signal to the time-frequency domain.
For example, MN data signals
Mapped to the time-frequency domain, each data signal occupies a time-frequency resource grid, as shown in fig. 4.
K3, the pilot signal in time-frequency domain (corresponding to the transformed pilot signal) is superposed with the data signal and then transmitted.
For example, the pilot signal (corresponding to the transformed pilot signal) in the time-frequency domain as shown in fig. 5a is superimposed with the data signal as shown in fig. 5b, and the superimposed signal as shown in fig. 5c is obtained and then transmitted; the stacked signals correspond to the formula:
wherein the content of the first and second substances,
which represents the transformed pilot signal, is,
representing a data signal. The TF in the upper right corner represents the time-frequency domain.
K4, the receiving terminal receives the wireless signal to obtain a corresponding received signal; the receiving end performs a finite fourier Transform (SFFT) on The received signal (belonging to a time-frequency signal) and transforms it to a delay-doppler domain. Detecting a pilot signal according to a preset discrimination threshold (corresponding to a preset detection threshold), and performing channel estimation to obtain a channel estimation result, wherein the first channel estimation on a certain receiving signal is initial channel estimation on a data signal without subtracting channel equalization, and the subsequent channel estimation on the certain receiving signal is intermediate channel estimation or final channel estimation on the data signal with subtracting channel equalization;
wherein, the formula corresponding to the SFFT is as follows:
for example, the receiving end first performs a finite 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 understood 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:
wherein, H [ k, l]K, l in the delay-Doppler domain]The channel state parameter (i.e. the channel estimation result to be determined), N is obeyed to N (0, σ) 2 ) Gaussian noise of (x) d Representing a data signal, x d [k,l]In the delay-Doppler domain [ k, l ]]Data signal of (x) p Representing the pilot signal, x p [k,l]K, l in the delay-Doppler domain]A pilot signal of (c). It should be understood that k, l of the delay-Doppler domain]Where denotes the resource block corresponding to the k-th delay interval and the l-th doppler interval. When estimating the channel, the pilot signal is detected according to the judging threshold value. If the data symbol in fig. 5 is regarded as data interference after being transformed to the delay-doppler domain, an initial discrimination threshold value is generally preset to be a value when initial channel estimation is performed; when channel estimation is carried out on a certain receiving signal subsequently, the expected power of data interference and the power of additive white noise are considered in a combined mode, and the judgment threshold value is adjusted dynamically. Dynamic discrimination threshold value set to
Wherein, the SINR P Represents the signal to interference plus noise ratio of the pilot signal,
e { } denotes expectation, x d Representing a data signal, σ 2 Represents a white noise variance and is E { x d } 2 ＝SNR d σ 2 ，SNR d Representing the signal-to-noise ratio of the data signal. 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 value 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, the received signal is as shown in fig. 6a, and after the received signal is converted from the time-frequency domain to the delay-doppler domain, the detected pilot signal is as shown in fig. 6b (it should be understood that, although there is only one pilot signal in the corresponding illustration of fig. 3a, the receiving end receives the corresponding pilot signals at different resource blocks due to the multipath effect, for example, 4 pilot signals are received as shown in fig. 6 b). It should be understood that the above dynamic discrimination threshold is only exemplary, and only intended to illustrate that the channel estimation may be performed with multiple iterations to obtain a better channel estimation result, and there are other initial setting and adjusting manners of the discrimination threshold for channel estimation that can be applied in the present invention, which is not limited in any way by the present invention.
And K5, the receiving end performs channel equalization of the data signal 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 cancellation, repeating the steps for a preset number of times, and then switching 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, and performs interference cancellation on the DD domain signal based on the signal detection result to remove interference of the data signal and the additive white noise on the pilot; and taking the DD domain signal after the 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 the threshold value according to the signal-to-noise ratio of the current data signal and the signal-to-noise ratio of the pilot signal. Generally iterating for 2-5 times to obtain a final channel estimation result with higher reliability;
k7, according to the final channel estimation result and the received signal, demodulating and decoding the data signal.
The receiving end detects the data signal according to the final channel estimation result to obtain the data to be decoded, and finally decodes the data to obtain the information bit. For example, at the receiving end, according to the finally obtained channel estimation result, subtracting the pilot signal from the received signal, and performing channel equalization on the obtained signal with the pilot signal subtracted, so as 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 mode 2
According to an embodiment of the present invention, there is provided a method of placing a pilot signal, including: obtaining a pilot signal, mapping the pilot signal to a delay-doppler domain, and then transforming the time-doppler domain to a time-frequency domain to obtain a transformed pilot signal (for details, refer to step S2 in embodiment 1, and details are not described here); obtaining a data signal, mapping the data signal to a time-frequency domain, and superimposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a stacked signal (for details, refer to step S3 in embodiment 1, and details are not described here again).
Embodiment 3
According to an embodiment of the present invention, there is provided a method of transmitting a wireless signal, including: obtaining information bits, and performing coding modulation on the information bits to obtain a data signal (for details, refer to step S1 in embodiment 1, and are not described herein again);
obtaining a pilot signal, mapping the pilot signal to a delay-doppler domain, and then transforming the time-doppler domain to a time-frequency domain to obtain a transformed pilot signal (for details, refer to step S2 in embodiment 1, and details are not described here); obtaining a data signal, mapping the data signal to a time-frequency domain, and superimposing the transformed pilot signal and the data signal in the time-frequency domain to obtain a stacked signal (for details, refer to step S3 in embodiment 1, and details are not described herein); the overlapped signals are transmitted in the form of wireless signals (for details, refer to step S4 in embodiment 1, 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 according to the method for transmitting a wireless signal in embodiment 3; the received signal is transformed into the delay-doppler domain and then channel estimation is performed to obtain a channel estimation result (for details, refer to step S6 in embodiment 1, which is not described herein again).
Embodiment 5
According to an embodiment of the present invention, there is provided a signal processing method including: receiving a wireless signal transmitted by the method for transmitting a wireless signal according to embodiment 3 to obtain a corresponding received signal; performing channel estimation on a channel transmitting a wireless signal according to the channel estimation method and a received signal corresponding to the wireless signal in embodiment 4 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 (for details, refer to step S7 in embodiment 1, and details are not repeated here).
It should be noted that, although the steps are described in a specific order, the steps are not necessarily 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 therewith for causing a processor to implement various 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 memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory 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: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device, such as punch cards or in-groove projection structures having instructions stored thereon, and any suitable combination of the foregoing.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not 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 described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A method for placing pilot signals, 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.
2. The method of claim 1, wherein the transformed pilot signal and the data signal are linearly superimposed in a time-frequency domain to obtain a superimposed signal.
3. The method of claim 1 or 2, wherein the pilot signal is linearly superimposed on the time slot resource occupied by the data signal, and does not occupy other time slot resources than the time slot resource occupied by the data signal.
4. A method of transmitting a wireless signal, comprising:
acquiring information bits, and performing coding modulation on the information bits to obtain data signals;
superimposing a pilot signal on a data signal based on the method of placing a pilot signal of any of claims 1 to 3, resulting in a superimposed signal;
the superimposed signal is transmitted as a wireless signal.
5. A method of channel estimation, comprising:
acquiring a received signal corresponding to a wireless signal transmitted by the method for transmitting a wireless signal according to claim 4;
and converting the received signal into a delay Doppler domain, and then performing channel estimation to obtain a channel estimation result.
6. The channel estimation method according to claim 5, wherein the step of performing channel estimation after transforming the received signal to the delay-doppler domain to obtain the channel estimation result comprises:
after converting the received signal to a delay-Doppler domain, detecting a pilot signal from the received signal represented by the delay-Doppler domain according to a predetermined detection threshold value to obtain an initial channel estimation result;
performing channel equalization on the data signal in the received signal based on the initial channel estimation result to obtain a data signal after the channel equalization;
subtracting a data signal and noise obtained by performing channel equalization on a data signal in the received signal according to a current channel estimation result from the received signal to obtain a received signal subjected to interference elimination;
and after the received signal after the interference elimination is converted into a delay Doppler domain, detecting a pilot signal from the received signal after the interference elimination represented by the delay Doppler domain according to a preset detection threshold value to obtain a channel estimation result.
7. A signal processing method, comprising:
receiving a wireless signal transmitted by the method for transmitting a wireless signal according to claim 4 to obtain a corresponding received signal;
the channel estimation method according to claim 5 or 6 and the received signal corresponding to the wireless signal perform channel estimation on a channel transmitting the wireless signal 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.
8. A wireless communication method for a wireless communication system including a transmitting end and a receiving end, the wireless communication method comprising:
acquiring information bits by a transmitting terminal, and carrying out coding modulation on the information bits to obtain data signals;
acquiring a pilot signal by a transmitting terminal, 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 by a transmitting terminal, 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;
transmitting the superposed signals in the form of wireless signals by a transmitting terminal;
receiving the wireless signal sent by the transmitting terminal by the receiving terminal to obtain a corresponding received signal;
converting the received signal to a delay Doppler domain by a receiving end and then carrying 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 so as to extract the information bit.
9. A computer-readable storage medium, on which a computer program is stored which is executable by a processor for carrying out the steps of the method according to any one of claims 1 to 8.
10. An electronic device, comprising:
one or more processors; and
a memory, wherein the memory is to store executable instructions;
the one or more processors are configured to implement the steps of the method of any one of claims 1-8 via execution of the executable instructions.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115714704A (en) * | 2022-11-08 | 2023-02-24 | 中国科学院计算技术研究所 | Signal modulation and transmission method based on transform domain and communication system |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101444055A (en) * | 2006-05-11 | 2009-05-27 | 艾利森电话股份有限公司 | Delay-Doppler channel response demodulation method and apparatus |
| CN105471802A (en) * | 2016-01-12 | 2016-04-06 | 上海工程技术大学 | Comb-type pilot OFDM system receiver |
| US20170012749A1 (en) * | 2012-06-25 | 2017-01-12 | Cohere Technologies, Inc. | Orthogonal time frequency space communication system compatible with ofdm |
| 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 |
| CN113098819A (en) * | 2021-04-01 | 2021-07-09 | 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 |
| CN113395221A (en) * | 2021-04-25 | 2021-09-14 | 北京邮电大学 | Orthogonal time-frequency-space joint-based channel estimation and symbol detection method |
| CN113612709A (en) * | 2021-08-17 | 2021-11-05 | 西安电子科技大学 | Channel estimation method based on joint placement of orthogonal time-frequency-space OTFS pilot frequency |
| 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 |
-
2022
- 2022-04-28 CN CN202210463122.9A patent/CN114884777A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101444055A (en) * | 2006-05-11 | 2009-05-27 | 艾利森电话股份有限公司 | Delay-Doppler channel response demodulation method and apparatus |
| US20170012749A1 (en) * | 2012-06-25 | 2017-01-12 | Cohere Technologies, Inc. | Orthogonal time frequency space communication system compatible with ofdm |
| CN105471802A (en) * | 2016-01-12 | 2016-04-06 | 上海工程技术大学 | Comb-type pilot OFDM system receiver |
| 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 |
| CN113098819A (en) * | 2021-04-01 | 2021-07-09 | 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 |
| CN113395221A (en) * | 2021-04-25 | 2021-09-14 | 北京邮电大学 | Orthogonal time-frequency-space joint-based channel estimation and symbol detection method |
| CN113612709A (en) * | 2021-08-17 | 2021-11-05 | 西安电子科技大学 | Channel estimation method based on joint placement of orthogonal time-frequency-space OTFS pilot frequency |
Non-Patent Citations (3)
| Title |
|---|
| HIMANSHU B. MISHRA等: ""OTFS Channel Estimation and Data Detection Designs With Superimposed Pilots"", 《》 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS * |
| P. RAVITEJA等: ""Embedded Pilot-Aided Channel Estimation for OTFS in Delay–Doppler Channels"", 《 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY》 * |
| WEIJIE YUAN等: ""Data-Aided Channel Estimation for OTFS Systems With a Superimposed Pilot and Data Transmission Scheme"", 《IEEE WIRELESS COMMUNICATIONS LETTERS 》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115714704A (en) * | 2022-11-08 | 2023-02-24 | 中国科学院计算技术研究所 | Signal modulation and transmission method based on transform domain and communication system |
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