CN109150783B - Channel estimation method and device - Google Patents

Channel estimation method and device Download PDF

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CN109150783B
CN109150783B CN201710508459.6A CN201710508459A CN109150783B CN 109150783 B CN109150783 B CN 109150783B CN 201710508459 A CN201710508459 A CN 201710508459A CN 109150783 B CN109150783 B CN 109150783B
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channel estimation
frequency domain
estimation value
virtual
virtual carrier
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CN109150783A (en
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徐晓亮
石璟
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Datang Mobile Communications Equipment Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols

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Abstract

The application discloses a channel estimation method and a channel estimation device, which are used for avoiding the generation of a time domain mirror image path and improving the accuracy of channel estimation when DFT channel estimation is adopted in a multi-user equipment scene. The channel estimation method provided by the application comprises the following steps: determining frequency domain receiving data of a symbol where a demodulation reference signal in each time slot is located, and performing initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of multi-user equipment to obtain a frequency domain channel estimation value; determining a virtual carrier by using a virtual carrier generating matrix, and adding the virtual carrier on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain; and determining a joint time domain channel estimation value of the multi-user equipment by utilizing the channel estimation values of the frequency domains with the virtual carriers added on the two sides.

Description

Channel estimation method and device
Technical Field
The present application relates to the field of communications technologies, and in particular, to a channel estimation method and apparatus.
Background
A Long Term Evolution (LTE) base station needs to perform Channel estimation using an Uplink (Up Link, UL) Demodulation Reference Signal (DMRS) when a Physical Uplink Shared Channel (PUSCH) receives symbol equalization. In a multi-User Multiple Input Multiple Output (MIMO) (Multiple Users MIMO, MU-MIMO) scene, a plurality of User Equipments (UEs) multiplex the same time-frequency resources, DMRS sequences of different UEs are distinguished by frequency domain phase rotation, and In a conventional channel estimation based on a Discrete Fourier Transform (DFT) method, a receiver distinguishes UEs by using the characteristic that CIRs of a plurality of UEs have cyclic displacement In a time domain and completes channel estimation respectively.
When the number of uplink Resource Blocks (RBs) is small (narrow band), the channel estimation based on DFT reduces the time domain resolution, the time domain windowing noise suppression effect is reduced, and the non-integer point sampling problem of time domain multipath is more obvious in the narrow band, which causes more serious time domain multipath energy leakage.
In order to solve the problem, in the prior art, a method of increasing a virtual carrier is mostly adopted to improve the time domain resolution, one method of increasing the virtual carrier is to increase a frequency domain mirror image, and the specific operation is to increase a symmetric mirror image (at this time, the number of IDFT points is increased) in the frequency domain channel estimation before an Inverse Discrete Fourier Transform (IDFT) operation, complete multipath resolution and windowing noise suppression in the time domain after the IDFT is completed, perform DFT operation after time domain processing, and then perform de-mirroring on frequency domain data to obtain final frequency domain channel estimation.
In summary, when a MU-MIMO scene is performed, CIRs of multiple UEs are arranged at multiple positions in the time domain, it is seen that a phase difference at a junction between an actual subcarrier and a virtual carrier is larger than that in an SU-MIMO scene in a frequency domain observation, when a channel estimation method based on a frequency domain mirror image is adopted, a phase mutation exists between a mirror image part and an original signal part, which may cause phase discontinuity in a frequency domain symbol (or explain that orthogonality of IDFT is destroyed), a false path (mirror image path) appears in a time domain observation, which destroys original multi-path resolution and windowing noise suppression rules, and increases Mean Squared Error (MSE) of channel estimation based on DFT. In order to avoid the problem, the CIR of each UE needs to be circularly shifted to the edge of the time domain axis and then the multipath search of the UE is performed, which causes each UE to complete IDFT/DFT operation, and the calculation complexity is high.
Disclosure of Invention
The embodiment of the application provides a channel estimation method and a channel estimation device, which are used for avoiding the generation of a time domain mirror image path and improving the accuracy of channel estimation when DFT channel estimation is adopted in a multi-user equipment scene.
The channel estimation method provided by the embodiment of the application comprises the following steps:
determining frequency domain receiving data of a symbol where a demodulation reference signal in each time slot is located, and performing initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of multi-user equipment to obtain a frequency domain channel estimation value;
determining a virtual carrier by using a virtual carrier generating matrix, and adding the virtual carrier on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain;
and determining a joint time domain channel estimation value of the multi-user equipment by utilizing the channel estimation values of the frequency domains with the virtual carriers added on the two sides.
In the method provided by the embodiment of the application, a generation mode of a virtual carrier is improved, namely a virtual carrier generation matrix is generated according to a mode that virtual carriers are arranged on two sides of a channel estimation value of a frequency domain, the virtual carrier is determined by using the virtual carrier generation matrix, the virtual carriers are added on two sides of the channel estimation value of the frequency domain, and a joint time domain channel estimation value of multi-user equipment is determined by using the channel estimation value of the frequency domain with the virtual carriers added on two sides, so that the generation of a time domain mirror image path is avoided in a multi-user equipment scene by improving the phase continuity of the virtual carriers and original subcarriers, and a channel estimation error is reduced.
Optionally, the virtual carrier generation matrix W is generated by using the following formula:
Figure GDA0002632999220000031
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure GDA0002632999220000032
Figure GDA0002632999220000033
n represents the number of resource blocks contained in the uplink resource multiplexed by a plurality of user equipments, K represents the number of virtual carriers added on each side of the channel estimation value of the frequency domain, p represents the frequency domain signal-to-noise ratio applied by the virtual carriers, I represents the unit diagonal matrix, and size (L)1) Represents L1Length of (1), F12N+2KIs a square matrix of (12N +2K) × (12N +2K), F12NA 12N by 12N square matrix;
Figure GDA0002632999220000034
is F12NU represents the number of user equipments.
Optionally, the following formula is adopted, and the virtual carrier is determined by using the virtual carrier generation matrix
Figure GDA0002632999220000035
Figure GDA0002632999220000036
Wherein
Figure GDA0002632999220000037
Wherein, the
Figure GDA0002632999220000038
A channel estimation value representing the frequency domain is shown,
Figure GDA0002632999220000039
and
Figure GDA00026329992200000310
respectively, indicating virtual carriers that need to be added on both sides of the channel estimation value in the frequency domain.
Optionally, determining a joint time domain channel estimation value of the multi-user equipment by using the channel estimation values of the frequency domains with the virtual carriers added on the two sides, specifically including:
calculating cyclic shift values of demodulation reference signals of user equipment
Figure GDA00026329992200000311
U-1, where j is 0.. U represents the number of user devices;
is calculated such that
Figure GDA00026329992200000312
The maximum value range of alpha and alpha is as follows: 0 to 12N-1;
completing the phase rotation of H by using the alpha obtained by calculation to obtain the channel estimation value H of the frequency domain after the phase rotationrWhere H denotes a channel estimation value of a frequency domain to which virtual carriers are added on both sides,
Figure GDA0002632999220000041
by means of HrA joint time domain channel estimate for the multi-user device is determined.
In the embodiment of the application, by analyzing the cyclic displacement values of the plurality of UEs and introducing additional phase rotation in the frequency domain before IDFT, the CIR configuration of the multi-user equipment avoids the midpoint position on the time domain axis, and the operation can avoid the large error of the channel estimation result of the UE with the CIR configuration near the midpoint of the time domain.
Alternatively, by HrDetermining a joint time domain channel estimation value of a multi-user device, specifically comprising:
for the HrWindowing to obtain Hw；
Calculate HwCorresponding time domain channel impulse response;
respectively calculating a multipath position and windowing noise suppression for each user equipment in the time domain channel impact response to obtain a joint time domain channel estimation value of a plurality of user equipment;
and calculating an inverse cyclic shift value for each user equipment, removing an extra cyclic shift value of the time domain channel estimation value of the user equipment by using the inverse cyclic shift value after removing the noise value outside a window, and converting the extra cyclic shift value into a frequency domain to finally obtain the frequency domain channel estimation value of the user equipment.
In the embodiment of the application, the frequency domain windowing operation is introduced before the IDFT operation, so that the problem of time domain energy leakage caused by the introduction of virtual carriers can be reduced, and the accuracy of channel estimation can be improved.
Optionally, for each user equipment, the following formula is adopted to determine the reverse cyclic shift value
Figure GDA0002632999220000042
Figure GDA0002632999220000043
U-1, wherein j is 0.
An embodiment of the present application provides a channel estimation apparatus, including:
a first unit, configured to determine frequency domain received data of a symbol in which a demodulation reference signal in each time slot is located, and perform initial channel estimation by using a base sequence in a demodulation reference signal transmission sequence of a multi-user device to obtain a frequency domain channel estimation value;
a second unit, configured to determine a virtual carrier by using a virtual carrier generation matrix, and add virtual carriers on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain;
and a third unit, configured to determine a joint time domain channel estimation value of the multi-user equipment by using the channel estimation values of the frequency domains with the virtual carriers added on both sides.
Optionally, the second unit generates the virtual carrier generation matrix W by using the following formula:
Figure GDA0002632999220000051
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure GDA0002632999220000052
Figure GDA0002632999220000053
u represents the number of user equipments, N represents the number of resource blocks included in the uplink resource multiplexed by a plurality of user equipments, K represents the number of virtual carriers added on each side of the channel estimation value of the frequency domain, p represents the frequency domain signal-to-noise ratio applied by the virtual carriers, and I represents the unit diagonal matrix.
Optionally, the second unit determines the virtual carrier by using the virtual carrier generation matrix according to the following formula
Figure GDA0002632999220000054
Figure GDA0002632999220000055
Wherein
Figure GDA0002632999220000056
Wherein, the
Figure GDA0002632999220000057
A channel estimation value representing the frequency domain is shown,
Figure GDA0002632999220000058
and
Figure GDA0002632999220000059
respectively, indicating virtual carriers that need to be added on both sides of the channel estimation value in the frequency domain.
Optionally, the third unit is specifically configured to:
calculating cyclic shift values of demodulation reference signals of user equipment
Figure GDA00026329992200000510
U-1, where j is 0.. U represents the number of user devices;
is calculated such that
Figure GDA00026329992200000511
The maximum value range of alpha and alpha is as follows: 0 to 12N-1;
completing the phase rotation of H by using the alpha obtained by calculation to obtain the channel estimation value H of the frequency domain after the phase rotationrWhere H denotes a channel estimation value of a frequency domain to which virtual carriers are added on both sides,
Figure GDA0002632999220000061
by means of HrA joint time domain channel estimate for the multi-user device is determined.
Optionally, the third unit utilizes HrDetermining a joint time domain channel estimation value of a multi-user device, specifically comprising:
for the HrWindowing to obtain Hw；
Calculate HwCorresponding time domain channel impulse response;
respectively calculating a multipath position and windowing noise suppression for each user equipment in the time domain channel impact response to obtain a joint time domain channel estimation value of a plurality of user equipment;
and calculating an inverse cyclic shift value for each user equipment, removing an extra cyclic shift value of the time domain channel estimation value of the user equipment by using the inverse cyclic shift value after removing the noise value outside a window, and converting the extra cyclic shift value into a frequency domain to finally obtain the frequency domain channel estimation value of the user equipment.
Optionally, the third unit determines the reverse cyclic shift value for each ue according to the following formula
Figure GDA0002632999220000062
Figure GDA0002632999220000063
U-1, wherein j is 0.
Another embodiment of the present application provides a computing device, which includes a memory and a processor, wherein the memory is used for storing program instructions, and the processor is used for calling the program instructions stored in the memory and executing any one of the above methods according to the obtained program.
Another embodiment of the present application provides a computer storage medium having stored thereon computer-executable instructions for causing a computer to perform any one of the methods described above.
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In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic general flowchart of a channel estimation method according to an embodiment of the present disclosure;
fig. 2 is a schematic flowchart of a channel estimation method according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a channel estimation apparatus according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a computing device according to an embodiment of the present application.
Detailed Description
The embodiment of the application provides a channel estimation method and a channel estimation device, which are used for avoiding the generation of a time domain mirror image path and improving the accuracy of channel estimation when DFT channel estimation is adopted in a multi-user equipment scene.
In a Physical Uplink Shared Channel (PUSCH) Channel estimation of a Long Term Evolution (LTE) Uplink, when the number of RBs scheduled and allocated by a User Equipment (UE) is small In a multi-User Multiple Input Multiple Output (MIMO) scenario, an error of a conventional DFT-based Channel estimation method is large. The method of adding virtual carriers in a mirror image mode is beneficial to reducing estimation errors, but the method of adding virtual carriers can cause multi-path energy leakage in a multi-user scene, and the channel estimation performance is deteriorated due to the mirror image path (the problem does not exist in a single-user scene). In order to adapt to a multi-user scenario, MU-MIMO time-domain Discrete Fourier Transform (DFT) channel estimation needs to perform time-frequency transformation on a user-by-user basis, the number of time-frequency transformations is increased by several times compared with conventional DFT channel estimation, and complexity is very high. The embodiment of the application provides a new improved scheme, which can avoid the occurrence of a mirror path while increasing the time domain resolution, and reduce the energy leakage of the original path, so that the Channel Impulse Response (CIR) processing of multiple UEs of MU-MIMO can be uniformly completed after one Inverse Discrete Fourier Transform (IDFT) operation, thereby avoiding performing IDFT operation on each UE, and reducing the computational complexity.
Specifically, aiming at the problem of channel estimation in an MU-MIMO scene, the embodiment of the application improves the generation mode of the virtual carrier, improves the phase continuity of the virtual carrier and the original subcarrier, avoids the generation of a time domain mirror path in a multi-user scene, and reduces the channel estimation error. In the embodiment of the application, cyclic shift parameters of a plurality of UEs are analyzed, and additional phase rotation is introduced in a frequency domain before IDFT, so that the CIR configuration of multiple users avoids the midpoint position (phase discontinuity obvious region) on a time domain axis. This operation can avoid the large error of the channel estimation result of the UE with CIR arranged near the middle point of the time domain. In addition, a frequency domain windowing operation is introduced before the IDFT operation, so that time domain energy leakage caused by introduction of virtual carriers is reduced.
In the embodiment of the present application, the real carrier is a frequency domain position where data and pilot are actually carried in OFDM, and the virtual carrier is a frequency domain position where data and pilot are not carried.
The technical solutions provided by the embodiments of the present application are described below with reference to the accompanying drawings.
Referring to fig. 1, a channel estimation method provided in an embodiment of the present application includes:
s101, determining frequency domain receiving data of a symbol where a demodulation reference signal in each time slot is located, and performing initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of multi-user equipment to obtain a channel estimation value of a frequency domain;
s102, determining a virtual carrier by using a virtual carrier generating matrix, and adding the virtual carrier on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain;
s103, determining a joint time domain channel estimation value of the multi-user equipment by using the channel estimation value of the frequency domain with the virtual carrier added on the two sides.
In the method provided by the embodiment of the application, a generation mode of a virtual carrier is improved, namely a virtual carrier generation matrix is generated according to a mode that virtual carriers are arranged on two sides of a channel estimation value of a frequency domain, the virtual carrier is determined by using the virtual carrier generation matrix, the virtual carriers are added on two sides of the channel estimation value of the frequency domain, and a joint time domain channel estimation value of multi-user equipment is determined by using the channel estimation value of the frequency domain with the virtual carriers added on two sides, so that the generation of a time domain mirror image path is avoided in a multi-user equipment scene by improving the phase continuity of the virtual carriers and original subcarriers, and a channel estimation error is reduced.
An illustration of one particular embodiment is given below.
Referring to fig. 2, an alternative specific process provided in the embodiment of the present application is as follows:
s201: in an MU-MIMO scenario, multiple uplink UEs have N Resource Blocks (RBs), a base station side completes Radio Frequency (RF) multi-antenna reception, and obtains a Frequency domain signal Y of a DMRS symbol in each slot after Digital Front End (DFE) or Fast Fourier Transform (FFT) processingi12N-1, where i denotes a subcarrier index.
S202: base sequence X in DMRS transmission sequence using multiple UEsi12N-1, performing initial channel estimation based on a Least Square (LS) method, and obtaining a frequency domain representation of the channel estimation
Figure GDA0002632999220000091
The method specifically comprises the following steps:
Figure GDA0002632999220000092
wherein i ═ 0.. 12N-1.
S203: defining the virtual carrier arrangement as increasing
Figure GDA0002632999220000093
Two sides wherein
Figure GDA0002632999220000094
For vector representation, increase in
Figure GDA0002632999220000095
Two sides are that some elements are added at the head and the tail of the vector respectively, the number of virtual carriers is increased to K on each side, and Q point DFT is defined (Q point DFT means that the calculation scale of DFT is Q point, namely FQOf size Q) to FQ(m, n) wherein F represents DFTFor example, the output frequency domain index set is {0, 1, …, N-1}, where the index set m may be {0, 1, 2, 3 }. The frequency domain snr for the virtual carrier application is defined as p, and in order to maintain the virtual carrier snr higher than the original carrier, a lower preset snr is adopted here (for example, snr is 0 db). Calculating a virtual carrier generation matrix W by adopting the following formula:
Figure GDA0002632999220000096
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure GDA0002632999220000097
Figure GDA0002632999220000098
wherein, the dimension of W is 2K 12N, the virtual carrier generation matrix W can be calculated in advance and stored as a constant lookup table.
F is a standard FFT matrix, a square matrix, F12NNamely, 12N × 12N square matrix, the other similar operations will not be described herein again.
Wherein, size (L)1) Represents L1Length of (d).
I denotes the unit diagonal matrix.
U denotes the number of user equipments.
Therefore, through the step, the generation mode of the virtual carrier is improved, and the optimization minimization target of the virtual carrier generation matrix is as follows: before and after the virtual carrier is added, the mean square error of the channel estimation of the original subcarrier is reduced, the generation of a time domain mirror image path can be reduced in an MU-MIMO scene, and the channel estimation error is reduced.
S204: and (3) applying the virtual carrier generation matrix W to generate virtual carriers:
Figure GDA0002632999220000101
wherein
Figure GDA0002632999220000102
Respectively to be provided with
Figure GDA0002632999220000103
And
Figure GDA0002632999220000104
add to
Figure GDA0002632999220000105
Two sides (i.e. vectors)
Figure GDA0002632999220000106
Head and tail) to yield:
Figure GDA0002632999220000107
s205: defining the number of the UE as U, and obtaining the DMRS cyclic shift value of each UE
Figure GDA0002632999220000108
U-1, wherein j is 0.. U-1; defining an additional shift value alpha, attempting to calculate alpha such that
Figure GDA0002632999220000109
Figure GDA00026329992200001010
Maximum, the value range of α is: 0 to 12N-1. And completing the phase rotation of H by using the calculated alpha to obtain:
Figure GDA00026329992200001011
the calculation of the DMRS cyclic shift value of each UE may be implemented by using the prior art specified in the LTE standard, for example, the DMRS cyclic shift value of each UE is calculated by using the following formula:
Figure GDA00026329992200001012
details are not repeated.
In step S205, the time domain channel responses of the UEs are distributed as far as possible from the midpoint of the time domain axis, so that the phase change of the frequency domain channel responses of the UEs at the junction between the real carrier and the virtual carrier is minimized.
The cyclic displacement parameters of a plurality of UE are analyzed, and additional phase rotation is introduced in a frequency domain before IDFT, so that the CIR configuration of multiple users avoids the midpoint position on the whole time domain axis, and the channel estimation error of the UE with special displacement is avoided from being large.
S206: in order to reduce the time-domain leakage of the channel response after the subsequent DFT, the frequency-domain channel response H obtained in the previous steprUpper window Wh(Hamming Window), the concrete operation is: hw＝Hr.*Wh。
In the step, frequency domain windowing operation is introduced before IDFT operation, reverse windowing operation is not needed after DFT operation, and the frequency domain windowing can reduce Gibbs effect of edges in a time domain result, so that time domain energy leakage caused by introduction of virtual carriers is reduced. Because the frequency domain windowing transition location is concentrated on the virtual carrier, no reverse window operation needs to be added after the subsequent DFT operation.
S207: and calculating time domain channel impact responses of the multiple UEs by using IDFT:
Figure GDA0002632999220000111
s208: the following operations are completed for each UE in the time domain channel impact response: and calculating the multipath position, and windowing and suppressing noise. And then, obtaining combined time domain channel estimation h of multiple UE, wherein the operation completes the channel estimation of all UE in the time domain once, specifically, one IDFT operation obtains the time domain impact response of all UE, and then calculates the multipath position and windowing noise suppression operation for each UE, thus avoiding the IDFT operation for multiple times.
S209: for each UE, the reverse cyclic shift is done in the time domain (reverse process of step S205):
Figure GDA0002632999220000112
wherein j ═ 0.. U-1, additional cyclic shifts are removed simultaneously in this operation.
S210: for each UE, after noise values outside a window are removed, DFT operation is completed to obtain frequency domain channel estimation of the current UE
Figure GDA0002632999220000113
U-1, with j ═ 0
Figure GDA0002632999220000114
Wherein
Figure GDA0002632999220000115
Means to cyclically shift h
Figure GDA0002632999220000116
Therefore, the CIR processing of the multiple UEs is completed uniformly after one IDFT operation, so that the IDFT operation of each UE is avoided, and the calculation complexity is reduced.
The following describes the apparatus provided in the embodiments of the present application.
In correspondence with the above method, referring to fig. 3, an embodiment of the present application provides a channel estimation apparatus, including:
a first unit 11, configured to determine frequency domain received data of a symbol where a demodulation reference signal in each time slot is located, and perform initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of a multi-user device to obtain a frequency domain channel estimation value;
a second unit 12, configured to determine a virtual carrier by using a virtual carrier generation matrix, and add virtual carriers on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain;
a third unit 13, configured to determine a joint time domain channel estimation value of the multi-user device by using channel estimation values of frequency domains with virtual carriers added on both sides.
Optionally, the second unit generates the virtual carrier generation matrix W by using the following formula:
Figure GDA0002632999220000121
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure GDA0002632999220000122
Figure GDA0002632999220000123
u represents the number of user equipments, N represents the number of resource blocks included in the uplink resource multiplexed by a plurality of user equipments, K represents the number of virtual carriers added on each side of the channel estimation value of the frequency domain, p represents the frequency domain signal-to-noise ratio applied by the virtual carriers, and I represents the unit diagonal matrix.
Optionally, the second unit determines the virtual carrier by using the virtual carrier generation matrix according to the following formula
Figure GDA0002632999220000124
Figure GDA0002632999220000125
Wherein
Figure GDA0002632999220000126
Wherein, the
Figure GDA0002632999220000127
A channel estimation value representing the frequency domain is shown,
Figure GDA0002632999220000128
and
Figure GDA0002632999220000129
respectively, indicating virtual carriers that need to be added on both sides of the channel estimation value in the frequency domain.
Optionally, the third unit is specifically configured to:
calculating cyclic shift values of demodulation reference signals of user equipment
Figure GDA00026329992200001210
U-1, where j is 0.. U represents the number of user devices;
is calculated such that
Figure GDA00026329992200001211
The maximum value range of alpha and alpha is as follows: 0 to 12N-1;
completing the phase rotation of H by using the alpha obtained by calculation to obtain the channel estimation value H of the frequency domain after the phase rotationr，
Figure GDA0002632999220000131
Where H denotes channel estimation values of frequency domains to which virtual carriers are added on both sides,
Figure GDA0002632999220000132
by means of HrA joint time domain channel estimate for the multi-user device is determined.
Optionally, the third unit utilizes HrDetermining a joint time domain channel estimation value of a multi-user device, specifically comprising:
for the HrCarry out windowing WhTo obtain Hw，Hw＝Hr.*Wh；
Calculate HwCorresponding time domain channel impulse response
Figure GDA0002632999220000133
Respectively calculating a multipath position and windowing noise suppression for each user equipment in the time domain channel impact response to obtain a joint time domain channel estimation value h of a plurality of user equipment;
for each user equipmentCalculating the inverse cyclic shift value
Figure GDA0002632999220000134
U-1, removing the noise value outside the window, removing the additional cyclic shift value of the time domain channel estimation value of the ue by using the inverse cyclic shift value, converting the additional cyclic shift value into a frequency domain, and finally obtaining the frequency domain channel estimation value of the ue
Figure GDA0002632999220000135
Optionally, the third unit determines the reverse cyclic shift value for each ue according to the following formula
Figure GDA0002632999220000136
Figure GDA0002632999220000137
U-1, wherein j is 0.
In addition to the above devices, the present application provides a computing device, which may be specifically a desktop computer, a portable computer, a smart phone, a tablet computer, a Personal Digital Assistant (PDA), and the like. As shown in fig. 4, the computing device may include a Central Processing Unit (CPU), a memory, an input/output device, etc., the input device may include a keyboard, a mouse, a touch screen, etc., and the output device may include a Display device, such as a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT), etc.
The memory may include Read Only Memory (ROM) and Random Access Memory (RAM), and provides the processor with program instructions and data stored in the memory. In the embodiment of the present application, the memory may be configured to store a program of the channel estimation method provided in the embodiment of the present application.
The processor is used for executing the following steps according to the obtained program instructions by calling the program instructions stored in the memory: determining frequency domain receiving data of a symbol where a demodulation reference signal in each time slot is located, and performing initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of multi-user equipment to obtain a frequency domain channel estimation value; determining a virtual carrier by using a virtual carrier generating matrix, and adding the virtual carrier on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain; and determining a joint time domain channel estimation value of the multi-user equipment by utilizing the channel estimation values of the frequency domains with the virtual carriers added on the two sides.
Embodiments of the present application provide a computer storage medium for storing computer program instructions for the above-mentioned computing device, which includes a program for executing the above-mentioned channel estimation method.
The computer storage media may be any available media or data storage device that can be accessed by a computer, including, but not limited to, magnetic memory (e.g., floppy disks, hard disks, magnetic tape, magneto-optical disks (MOs), etc.), optical memory (e.g., CDs, DVDs, BDs, HVDs, etc.), and semiconductor memory (e.g., ROMs, EPROMs, EEPROMs, non-volatile memory (NAND FLASH), Solid State Disks (SSDs)), etc.
To sum up, the technical solution provided in the embodiment of the present application improves a generation manner of a virtual carrier, that is, a virtual carrier generation matrix is generated according to a position relationship between the virtual carrier and a channel estimation value of a frequency domain, determines the virtual carrier by using the virtual carrier generation matrix, adds virtual carriers on both sides of the channel estimation value of the frequency domain, and determines a joint time domain channel estimation value of a multi-user device by using channel estimation values of the frequency domain with the virtual carriers added on both sides, so that by improving phase continuity between the virtual carrier and an original subcarrier, generation of a time domain mirror image path is avoided in a multi-user device scenario, and a channel estimation error is reduced. Further, in the embodiment of the present application, by analyzing cyclic shift values of a plurality of UEs and introducing additional phase rotation in the frequency domain before IDFT, the CIR configuration of the multi-user device is enabled to avoid a midpoint position on the time domain axis, and this operation can avoid an error of a channel estimation result of the UE whose CIR configuration is near the midpoint of the time domain from being large. Furthermore, in the embodiment of the present application, a frequency domain windowing operation is introduced before the IDFT operation, so that the problem of time domain energy leakage caused by the introduction of a virtual carrier can be reduced, and the accuracy of channel estimation can be improved.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (11)

1. A method for channel estimation, the method comprising:
determining frequency domain receiving data of a symbol where a demodulation reference signal in each time slot is located, and performing initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of multi-user equipment to obtain a frequency domain channel estimation value;
determining a virtual carrier by using a virtual carrier generating matrix, and adding the virtual carrier on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain;
determining a joint time domain channel estimation value of the multi-user equipment by utilizing the channel estimation values of the frequency domains with virtual carriers added on the two sides;
adding virtual carriers on two sides of the channel estimation value of the frequency domain comprises:
adding corresponding elements on two sides of the channel estimation value of the frequency domain, wherein the number of virtual carriers on each side is K;
generating the virtual carrier generation matrix W by adopting the following formula:
Figure FDA0002632999210000011
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure FDA0002632999210000012
Figure FDA0002632999210000013
u represents the number of user equipments, N represents the number of resource blocks included in the uplink resource multiplexed by a plurality of user equipments, K represents the number of virtual carriers added on each side of the channel estimation value of the frequency domain, p represents the frequency domain signal-to-noise ratio applied by the virtual carriers, I represents a unit diagonal matrix, and size (L)1) Represents L1Length of (1), F12N+2KIs a square matrix of (12N +2K) × (12N +2K), F12NA 12N by 12N square matrix;
Figure FDA0002632999210000014
is F12NThe conjugate transpose matrix of (2).
2. The method of claim 1, wherein the virtual carrier generation matrix is used to determine the virtual carrier according to the following formula
Figure FDA0002632999210000021
Figure FDA0002632999210000022
Wherein
Figure FDA0002632999210000023
Wherein, the
Figure FDA0002632999210000024
A channel estimation value representing the frequency domain is shown,
Figure FDA0002632999210000025
and
Figure FDA0002632999210000026
respectively, indicating virtual carriers that need to be added on both sides of the channel estimation value in the frequency domain.
3. The method according to claim 2, wherein determining the joint time domain channel estimation value of the multi-user equipment by using the channel estimation values of the frequency domains with the virtual carriers added at both sides comprises:
calculating cyclic shift values of demodulation reference signals of user equipment
Figure FDA0002632999210000027
U-1, where j is 0.. U represents the number of user devices;
is calculated such that
Figure FDA0002632999210000028
The maximum value range of alpha and alpha is as follows: 0 to 12N-1;
completing the phase rotation of H by using the alpha obtained by calculation to obtain the channel estimation value H of the frequency domain after the phase rotationrWhere H denotes a channel estimation value of a frequency domain to which virtual carriers are added on both sides,
Figure FDA0002632999210000029
by means of HrDetermining a joint time domain channel estimation value of multi-user equipment;
wherein the phase rotation of H is accomplished using the calculated α by:
Figure FDA00026329992100000210
4. method according to claim 3, characterized in that H is utilizedrDetermining a joint time domain channel estimation value of a multi-user device, specifically comprising:
for the HrWindowing to obtain Hw；
Calculate HwCorresponding time domain channel impulse response;
respectively calculating a multipath position and windowing noise suppression for each user equipment in the time domain channel impact response to obtain a joint time domain channel estimation value of a plurality of user equipment;
and calculating an inverse cyclic shift value for each user equipment, removing an extra cyclic shift value of the time domain channel estimation value of the user equipment by using the inverse cyclic shift value after removing the noise value outside a window, and converting the extra cyclic shift value into a frequency domain to finally obtain the frequency domain channel estimation value of the user equipment.
5. The method of claim 4, wherein the inverse cyclic shift value is determined for each UE using the following formula
Figure FDA0002632999210000031
Figure FDA0002632999210000032
U-1, wherein j is 0.
6. A channel estimation device, comprising:
a first unit, configured to determine frequency domain received data of a symbol in which a demodulation reference signal in each time slot is located, and perform initial channel estimation by using a base sequence in a demodulation reference signal transmission sequence of a multi-user device to obtain a frequency domain channel estimation value;
a second unit, configured to determine a virtual carrier by using a virtual carrier generation matrix, and add virtual carriers on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to an arrangement mode that virtual carriers are arranged at two sides of the channel estimation value of the frequency domain;
a third unit, configured to determine a joint time domain channel estimation value of the multi-user device by using a channel estimation value of a frequency domain to which virtual carriers are added on both sides;
adding virtual carriers on two sides of the channel estimation value of the frequency domain comprises:
adding corresponding elements on two sides of the channel estimation value of the frequency domain, wherein the number of virtual carriers on each side is K;
the second unit generates the virtual carrier generation matrix W by using the following formula:
Figure FDA0002632999210000033
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure FDA0002632999210000034
Figure FDA0002632999210000035
u represents the number of user equipments, N represents the number of resource blocks included in the uplink resource multiplexed by a plurality of user equipments, K represents the number of virtual carriers added on each side of the channel estimation value of the frequency domain, p represents the frequency domain signal-to-noise ratio applied by the virtual carriers, I represents a unit diagonal matrix, and size (L)1) Represents L1Length of (1), F12N+2KIs a square matrix of (12N +2K) × (12N +2K), F12NA 12N by 12N square matrix;
Figure FDA0002632999210000041
is F12NThe conjugate transpose matrix of (2).
7. The apparatus of claim 6, wherein the second unit determines the virtual carrier by using the virtual carrier generation matrix according to the following formula
Figure FDA0002632999210000042
Figure FDA0002632999210000043
Wherein
Figure FDA0002632999210000044
Wherein, the
Figure FDA0002632999210000045
A channel estimation value representing the frequency domain is shown,
Figure FDA0002632999210000046
and
Figure FDA0002632999210000047
respectively, indicating virtual carriers that need to be added on both sides of the channel estimation value in the frequency domain.
8. The apparatus according to claim 7, wherein the third unit is specifically configured to:
calculating cyclic shift values of demodulation reference signals of user equipment
Figure FDA0002632999210000048
U-1, where j is 0.. U represents the number of user devices;
is calculated such that
Figure FDA0002632999210000049
The maximum value range of alpha and alpha is as follows: 0 to 12N-1;
completing the phase rotation of H by using the alpha obtained by calculation to obtain the channel estimation value H of the frequency domain after the phase rotationrWhere H denotes a channel estimation value of a frequency domain to which virtual carriers are added on both sides,
Figure FDA00026329992100000410
by means of HrDetermining a joint time domain channel estimation value of multi-user equipment;
wherein the phase rotation of H is accomplished using the calculated α by:
Figure FDA00026329992100000411
9. the apparatus of claim 8, wherein the third unit utilizes HrDetermining a joint time domain channel estimation value of a multi-user device, specifically comprising:
for the HrWindowing to obtain Hw；
Calculate HwCorresponding time domain channel impulse response;
respectively calculating a multipath position and windowing noise suppression for each user equipment in the time domain channel impact response to obtain a joint time domain channel estimation value of a plurality of user equipment;
and calculating an inverse cyclic shift value for each user equipment, removing an extra cyclic shift value of the time domain channel estimation value of the user equipment by using the inverse cyclic shift value after removing the noise value outside a window, and converting the extra cyclic shift value into a frequency domain to finally obtain the frequency domain channel estimation value of the user equipment.
10. The apparatus of claim 9, wherein the third unit determines an inverse cyclic shift value for each UE using the following formula
Figure FDA0002632999210000051
Figure FDA0002632999210000052
U-1, wherein j is 0.
11. A computing device, comprising:
a memory for storing program instructions;
a processor for calling the program instructions stored in the memory and executing according to the obtained program: determining frequency domain receiving data of a symbol where a demodulation reference signal in each time slot is located, and performing initial channel estimation by using a base sequence in a demodulation reference signal sending sequence of multi-user equipment to obtain a frequency domain channel estimation value; determining a virtual carrier by using a virtual carrier generating matrix, and adding the virtual carrier on two sides of the channel estimation value of the frequency domain; the virtual carrier generation matrix is generated according to the position relation between the virtual carrier and the channel estimation value of the frequency domain; determining a joint time domain channel estimation value of the multi-user equipment by utilizing the channel estimation values of the frequency domains with virtual carriers added on the two sides;
adding virtual carriers on two sides of the channel estimation value of the frequency domain comprises:
adding corresponding elements on two sides of the channel estimation value of the frequency domain, wherein the number of virtual carriers on each side is K;
generating the virtual carrier generation matrix W by adopting the following formula:
Figure FDA0002632999210000053
wherein:
V＝0…K-1,12N+K…12N+2K-1；
M＝0…12N-1；
Figure FDA0002632999210000061
Figure FDA0002632999210000062
u represents the number of user equipments, N represents the number of resource blocks included in an uplink resource multiplexed by a plurality of user equipments, and K represents an added virtual channel estimation value on each side of the frequency domain channel estimation valueNumber of carriers, p denotes the frequency domain signal-to-noise ratio for virtual carrier applications, I denotes the unity diagonal matrix, size (L)1) Represents L1Length of (1), F12N+2KIs a square matrix of (12N +2K) × (12N +2K), F12NA 12N by 12N square matrix;
Figure FDA0002632999210000063
is F12NThe conjugate transpose matrix of (2).
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