CN110636019A - Channel estimation method and device for narrow-band carrier aggregation system, storage medium and terminal - Google Patents
Channel estimation method and device for narrow-band carrier aggregation system, storage medium and terminal Download PDFInfo
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- CN110636019A CN110636019A CN201911067764.1A CN201911067764A CN110636019A CN 110636019 A CN110636019 A CN 110636019A CN 201911067764 A CN201911067764 A CN 201911067764A CN 110636019 A CN110636019 A CN 110636019A
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
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- H04L25/0202—Channel estimation
- H04L25/0204—Channel estimation of multiple channels
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/024—Channel estimation channel estimation algorithms
- H04L25/0256—Channel estimation using minimum mean square error criteria
Abstract
A channel estimation method and device, storage medium and terminal for a narrowband carrier aggregation system are provided, the method comprises: acquiring an original channel estimation result of each carrier to be processed; for each carrier to be processed, determining a channel estimation mode at least according to the channel condition of the carrier to be processed; when the channel estimation mode indicates to perform cross-carrier estimation, determining a plurality of to-be-processed carriers to be cross-carrier estimated according to the position of the to-be-processed carriers in the narrowband carrier aggregation system and the number of cross-carriers included in the channel estimation mode; preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed; and obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results. The scheme provided by the invention can effectively improve the channel estimation precision of the narrow-band carrier aggregation system.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a channel estimation method and apparatus, a storage medium, and a terminal for a narrowband carrier aggregation system.
Background
In the field of wireless communications, spectrum is a very limited resource. A Narrow Band Carrier Aggregation System (Narrow Band Carrier Aggregation System) is a major focus of recent development of wireless communication technology because it can make full use of small bandwidth holes to effectively utilize a frequency spectrum.
Specifically, the principle of Carrier Aggregation (CA) is to aggregate two or more Carrier units (Component carriers, CCs) together to support a larger transmission bandwidth.
Unlike the existing Long Term Evolution (LTE) system, each carrier has a large number of subcarriers, and each carrier in the narrowband carrier aggregation system contains a small number of subcarriers, for example, 1 carrier may only contain 6 subcarriers. This results in poor channel estimation results and affects demodulation performance when the channel estimation method adopted by LTE is directly applied to the narrowband carrier aggregation system.
Disclosure of Invention
The technical problem solved by the invention is how to improve the channel estimation precision of the narrowband carrier aggregation system.
In order to solve the above technical problem, an embodiment of the present invention provides a channel estimation method for a narrowband carrier aggregation system, including: acquiring an original channel estimation result of each carrier to be processed in the narrow-band carrier aggregation system; for each carrier to be processed, determining a channel estimation mode at least according to the channel condition of the carrier to be processed, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm; when the channel estimation mode indicates to perform cross-carrier estimation, determining a plurality of to-be-processed carriers to be cross-carrier estimated according to the position of the to-be-processed carriers in the narrowband carrier aggregation system and the number of cross-carriers included in the channel estimation mode; preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed; and obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results.
Optionally, the original channel estimation result is a channel estimation result of a subcarrier with a pilot signal in a corresponding to-be-processed carrier, and when the channel estimation mode indicates that cross-carrier estimation is not performed, the channel estimation mode includes the channel estimation algorithm, and the channel estimation method further includes: and performing channel estimation on the subcarriers without pilot signals in the to-be-processed carriers by adopting a channel estimation algorithm included in the channel estimation mode and the original channel estimation result to obtain the preferred channel estimation result.
Optionally, the channel estimation algorithm includes: and MMSE, wherein the order of the MMSE is determined according to a preset correlation matrix, the preset correlation matrix is obtained based on the correlation matrix of the carrier to be processed, or the preset correlation matrix is obtained by averaging based on the correlation matrix of the carrier to be processed and the correlation matrix of the adjacent carrier to be processed.
Optionally, the channel condition includes: frequency selectivity; signal to noise ratio.
Optionally, the determining a channel estimation mode according to at least the channel condition of the to-be-processed carrier includes: determining a channel correlation estimation result according to the channel condition of the to-be-processed carrier and the channel condition of the adjacent to-be-processed carrier, wherein the channel correlation estimation result comprises a coherent bandwidth; and determining the channel estimation mode at least according to the channel correlation estimation result.
Optionally, the channel estimation algorithm includes: MMSE; the channel condition comprises a signal-to-noise ratio; the determining a channel estimation mode at least according to the channel condition of the to-be-processed carrier comprises: and determining the order of MMSE according to the signal-to-noise ratio.
Optionally, the preprocessing the original channel estimation results of the multiple to-be-processed carriers according to the channel estimation mode to estimate and compensate the phase difference between adjacent to-be-processed carriers in the multiple to-be-processed carriers includes: when the order of the MMSE is second order, determining the phase difference to be zero; and for each to-be-processed carrier in the plurality of to-be-processed carriers, taking the original channel estimation result of the to-be-processed carrier as a corresponding preprocessed original channel estimation result.
Optionally, the preprocessing the original channel estimation results of the multiple to-be-processed carriers according to the channel estimation mode to estimate and compensate the phase difference between adjacent to-be-processed carriers in the multiple to-be-processed carriers includes: when the order of the MMSE is greater than the second order, calculating the average phase difference of two adjacent to-be-processed carriers in the plurality of to-be-processed carriers; and performing phase difference compensation on the two adjacent to-be-processed carriers based on the average phase difference so as to enable the two adjacent to-be-processed carriers to be equivalent to two adjacent subcarriers in the same bandwidth.
Optionally, for each two adjacent to-be-processed carriers in the multiple to-be-processed carriers, calculating an average phase difference between the two adjacent to-be-processed carriers includes: the two adjacent carriers to be processed are respectively a first carrier and a second carrier, and a candidate channel of each subcarrier in an original channel estimation result of the first carrier and a candidate channel of each subcarrier in an original channel estimation result of the second carrier are respectively obtained; for each subcarrier included in the first carrier, calculating a phase difference between the subcarrier and each subcarrier of the second carrier based on a candidate channel associated with the first carrier; and determining the average value of all the calculated phase differences as the average phase difference.
Optionally, the obtaining of the preferred channel estimation result based on a combination of the plurality of preprocessed original channel estimation results includes: determining an average value of the plurality of preprocessed original channel estimation results as the preferred channel estimation result; or, performing weighted summation on the plurality of preprocessed original channel estimation results to obtain the preferred channel estimation result.
In order to solve the above technical problem, an embodiment of the present invention further provides a channel estimation device for a narrowband carrier aggregation system, including: the acquisition module is used for acquiring the original channel estimation result of each carrier to be processed in the narrowband carrier aggregation system; the first determining module is used for determining a channel estimation mode according to the channel condition of each to-be-processed carrier at least, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm; a second determining module, configured to determine, when the channel estimation mode indicates to perform cross-carrier estimation, a plurality of to-be-processed carriers to be estimated in a cross-carrier manner according to a position of the to-be-processed carrier in the narrowband carrier aggregation system and a number of cross-carriers included in the channel estimation mode; the compensation module is used for preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode so as to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed; and the processing module is used for obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results.
To solve the above technical problem, an embodiment of the present invention further provides a storage medium having stored thereon computer instructions, where the computer instructions execute the steps of the above method when executed.
In order to solve the above technical problem, an embodiment of the present invention further provides a terminal, including a memory and a processor, where the memory stores computer instructions capable of being executed on the processor, and the processor executes the computer instructions to perform the steps of the method.
Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:
the embodiment of the invention provides a channel estimation method for a narrow-band carrier aggregation system, which comprises the following steps: acquiring an original channel estimation result of each carrier to be processed in the narrow-band carrier aggregation system; for each carrier to be processed, determining a channel estimation mode at least according to the channel condition of the carrier to be processed, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm; when the channel estimation mode indicates to perform cross-carrier estimation, determining a plurality of to-be-processed carriers to be cross-carrier estimated according to the position of the to-be-processed carriers in the narrowband carrier aggregation system and the number of cross-carriers included in the channel estimation mode; preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed; and obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results. Compared with the prior technical scheme of constraining channel estimation only in a single carrier, the scheme of the embodiment of the invention can effectively improve the channel estimation precision of a narrow-band carrier aggregation system and optimize the demodulation performance. Specifically, whether cross-carrier fusion is required or not is determined according to the channel condition of the carrier to be processed, so that the finally obtained optimal channel estimation result is more consistent with the wireless signal environment in which the carrier to be processed is currently located, and the channel estimation accuracy can be improved. Further, when it is determined that cross-carrier fusion needs to be performed, phase differences between multiple carriers that need to be crossed are compensated, so that adjacent carriers can be equal to subcarriers in the same bandwidth, thereby effectively making up for the defect that channel estimation results are poor due to the fact that the number of subcarriers included in a single carrier in a narrowband carrier aggregation system is too small, and making it possible to perform channel estimation by using multiple carriers.
Further, the original channel estimation result is a channel estimation result of a subcarrier having a pilot signal in a corresponding to-be-processed carrier, and when the channel estimation mode indicates that cross-carrier estimation is not performed, the channel estimation mode includes the channel estimation algorithm, and the channel estimation method further includes: and performing channel estimation on the subcarriers without pilot signals in the to-be-processed carriers by adopting a channel estimation algorithm included in the channel estimation mode and the original channel estimation result to obtain the preferred channel estimation result. Therefore, when the original channel estimation result shows that cross-carrier fusion is not needed, such as high signal-to-noise ratio or narrow coherence characteristics, the original channel estimation can be performed on the position of the pilot signal, and then channel estimation of other subcarriers without the pilot signal can be performed according to the original channel estimation, so as to obtain the channel estimation result of the narrowband carrier aggregation system.
Drawings
Fig. 1 is a flowchart of a channel estimation method for a narrowband carrier aggregation system according to an embodiment of the present invention;
FIG. 2 is a flowchart of one embodiment of step S102 of FIG. 1;
FIG. 3 is a flowchart of one embodiment of step S104 of FIG. 1;
FIG. 4 is a flow diagram of another embodiment of step S104 of FIG. 1;
fig. 5 is a schematic structural diagram of a channel estimation apparatus for a narrowband carrier aggregation system according to an embodiment of the present invention.
Detailed Description
As mentioned in the background, the existing scheme for channel estimation in a single carrier is not suitable for the narrowband carrier aggregation system because the number of subcarriers included in the single carrier is too small.
In order to solve the above technical problem, an embodiment of the present invention provides a channel estimation method for a narrowband carrier aggregation system, including: acquiring an original channel estimation result of each carrier to be processed in the narrow-band carrier aggregation system; for each carrier to be processed, determining a channel estimation mode at least according to the channel condition of the carrier to be processed, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm; when the channel estimation mode indicates to perform cross-carrier estimation, determining a plurality of to-be-processed carriers to be cross-carrier estimated according to the position of the to-be-processed carriers in the narrowband carrier aggregation system and the number of cross-carriers included in the channel estimation mode; preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed; and obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results.
By adopting the scheme of the embodiment of the invention, the channel estimation precision of the narrowband carrier aggregation system can be effectively improved, and the demodulation performance is optimized. Specifically, whether cross-carrier fusion is required or not is determined according to the channel condition of the carrier to be processed, so that the finally obtained optimal channel estimation result is more consistent with the wireless signal environment in which the carrier to be processed is currently located, and the channel estimation accuracy can be improved. Further, when it is determined that cross-carrier fusion needs to be performed, phase differences between multiple carriers that need to be crossed are compensated, so that adjacent carriers can be equal to subcarriers in the same bandwidth, thereby effectively making up for the defect that channel estimation results are poor due to the fact that the number of subcarriers included in a single carrier in a narrowband carrier aggregation system is too small, and making it possible to perform channel estimation by using multiple carriers.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 1 is a flowchart of a channel estimation method for a narrowband carrier aggregation system according to an embodiment of the present invention. The scheme of this embodiment may be applied to a User Equipment side, for example, executed by a User Equipment (UE).
Specifically, in this embodiment, referring to fig. 1, the channel estimation method for a narrowband carrier aggregation system may include the following steps:
step S101, obtaining an original channel estimation result of each carrier to be processed in the narrow-band carrier aggregation system;
step S102, for each carrier to be processed, determining a channel estimation mode at least according to the channel condition of the carrier to be processed, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm;
step S103, when the channel estimation mode indicates to perform cross-carrier estimation, determining a plurality of to-be-processed carriers to be cross-carrier estimated according to the positions of the to-be-processed carriers in the narrowband carrier aggregation system and the number of cross-carriers included in the channel estimation mode;
step S104, preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed;
step S105, obtaining a preferred channel estimation result based on a plurality of preprocessed original channel estimation results.
More specifically, each to-be-processed carrier is a carrier in the narrowband carrier aggregation system.
For example, the narrowband carrier aggregation system may include 480 independent carriers, where each carrier may have a bandwidth of 25 kilohertz (KHz), and each carrier may include 6 subcarriers, with a subcarrier spacing of 3.75 KHz.
In a specific embodiment, all 480 carriers included in the narrowband carrier aggregation system may be determined as the to-be-processed carrier. In step S101, channel estimation may be performed on all carriers in the narrowband carrier aggregation system, so as to obtain an original channel estimation result of each carrier.
For example, for each carrier of the 480 carriers, channel estimation may be performed on a subcarrier of the carriers with a pilot signal to obtain a raw channel estimation result for the carrier.
Specifically, the specific procedure of performing channel estimation on the carrier may refer to related operations related to channel estimation in the prior art, which are not described herein again.
In a variation, a partial carrier may be selected from 480 carriers included in the narrowband carrier aggregation system and determined as the pending carrier. In step S101, carriers within a specific bandwidth range may be selected from carriers included in the narrowband carrier aggregation system to perform channel estimation, respectively, so as to obtain an original channel estimation result.
In one implementation, the channel conditions may include: frequency selectivity; signal to noise ratio. In practical application, other parameters capable of measuring the wireless signal environment of the carrier can be selected as the channel condition.
For example, the channel condition may be determined from the raw channel estimation results.
In one implementation, referring to fig. 2, the step S102 may include the following steps:
step S1021, determining a channel correlation estimation result according to the channel condition of the to-be-processed carrier and the channel condition of the adjacent to-be-processed carrier, wherein the channel correlation estimation result comprises a coherent bandwidth;
step S1022, determining the channel estimation mode at least according to the channel correlation estimation result.
Specifically, for each to-be-processed carrier, a correlation matrix may be determined according to a channel condition of the to-be-processed carrier.
Further, according to the correlation matrix of the to-be-processed carrier and the adjacent to-be-processed carrier, the coherence bandwidth between channels can be determined.
Further, in the step S1022, the channel estimation mode may be determined by combining the coherence bandwidth and the scheduling of the base station.
In one variation, the channel correlation estimate may be determined in conjunction with the delay spread based on multipath estimates for different channels. Specifically, the delay spread is inversely proportional to the correlation.
In one implementation, the channel estimation algorithm may include: minimum Mean Square Error (MMSE for short).
Accordingly, in step S102, the order of the MMSE may be determined according to a preset correlation matrix.
Wherein the preset correlation matrix may be obtained based on the correlation matrix of the to-be-processed carrier.
For example, when the correlation matrix is an identity matrix (at this time, the channel correlation between carriers is 0), the order of the MMSE may be determined to be second order.
Or, the preset correlation matrix may be obtained by averaging based on the correlation matrix of the to-be-processed carrier and the correlation matrix of the adjacent to-be-processed carrier.
In one implementation, the order of the MMSE may be determined based on the signal-to-noise ratio.
Further, the signal-to-noise ratio may be associated with a distance of the UE and the base station.
For example, when the snr of the to-be-processed carrier is above 30dB, the MMSE order may be determined to be second order.
For another example, when the snr of the to-be-processed carrier is 0dB or less, the order of the MMSE may be determined to be sixth order.
In one variation, the order of the MMSE may be determined based on the average snr of the multiple carriers to be processed.
For example, for the multiple carriers to be processed, the snr of each carrier to be processed may be obtained through calculation, and then the average snr of the multiple carriers to be processed is obtained through calculation.
Specifically, the higher the snr is, the higher the MMSE accuracy is, and the more effective is the combination (bin) of the original channel estimation results. Thus, the higher the average signal-to-noise, the higher the order of performing MMSE may be to obtain a better channel estimation result with higher accuracy.
In a specific implementation, in the step S103, adjacent to-be-processed carriers whose bandwidths are located before and after the to-be-processed carrier may be determined according to the position of the to-be-processed carrier in the narrowband carrier aggregation system, and then a plurality of to-be-processed carriers that need to execute the step S104 may be determined according to the number of cross carriers indicated in the channel estimation mode.
For example, if the number of the cross carriers indicated by the channel estimation mode is 5, 2 to-be-processed carriers located before the to-be-processed carrier corresponding to the channel estimation mode and 2 to-be-processed carriers located after the to-be-processed carrier corresponding to the channel estimation mode may be determined together with the to-be-processed carriers as the plurality of to-be-processed carriers that need to be preprocessed in step S104.
For another example, if the number of the cross carriers indicated by the channel estimation mode is 5, then the to-be-processed carriers and the to-be-processed carriers that are located before the to-be-processed carrier corresponding to the channel estimation mode may be determined as multiple to-be-processed carriers that need to be preprocessed in step S104.
For another example, if the number of the cross carriers indicated by the channel estimation mode is 5, then the 4 to-be-processed carriers located after the to-be-processed carrier corresponding to the channel estimation mode and the to-be-processed carriers may be determined together as the multiple to-be-processed carriers that need to be preprocessed in step S104.
For another example, if the number of the cross carriers indicated by the channel estimation mode is 5, 1 to-be-processed carrier located before the to-be-processed carrier corresponding to the channel estimation mode and 3 to-be-processed carriers located after the to-be-processed carrier corresponding to the channel estimation mode may be determined together with the to-be-processed carriers as the plurality of to-be-processed carriers that need to be preprocessed in step S104.
For another example, if the number of the cross carriers indicated by the channel estimation mode is 5, then 3 to-be-processed carriers located before the to-be-processed carrier corresponding to the channel estimation mode and 1 to-be-processed carrier located after the to-be-processed carrier corresponding to the channel estimation mode may be determined together with the to-be-processed carriers as the multiple to-be-processed carriers that need to be preprocessed in step S104.
In practical applications, whether the adjacent to-be-processed carrier located before the to-be-processed carrier or the adjacent to-be-processed carrier located after the to-be-processed carrier is determined as the plurality of to-be-processed carriers that need to be preprocessed in step S104 together with the to-be-processed carrier may be flexibly adjusted according to channel conditions.
Further, in the step S104, a preprocessing manner of the original channel estimation result of the to-be-processed carrier may be determined in a targeted manner according to the corresponding order.
In one implementation, referring to fig. 3, the step S104 may include the following steps:
step S1041, when the order of the MMSE is second order, determining the phase difference to be zero;
step S1042, regarding each of the multiple to-be-processed carriers, taking the original channel estimation result of the to-be-processed carrier as a corresponding preprocessed original channel estimation result.
In particular, when the order of MMSE is second order, the current channel estimation may be considered to have a relatively low requirement for accuracy. Thus, it can be assumed that the phase difference of adjacent to-be-processed carriers among the plurality of to-be-processed carriers is approximately zero.
Correspondingly, the original channel estimation result of each to-be-processed carrier can be directly used as the corresponding preprocessed original channel estimation result to perform subsequent combination operation.
Further, in this embodiment, the step S105 may include: and acquiring the average value of the original channel estimation results of the carriers to be processed to obtain the optimal channel estimation result.
Alternatively, to improve the accuracy, the step S105 may include: and performing MMSE on the original channel estimation results of the multiple carriers to be processed based on second-order statistical characteristics to obtain linear weight of each original channel estimation result when the carriers are combined. Further, the original channel estimation results of the multiple carriers to be processed are weighted and averaged according to the linear weight to obtain the preferred channel estimation result.
In another implementation, referring to fig. 4, the step S104 may include the following steps:
step S1048, when the order of the MMSE is greater than second order, for each two adjacent to-be-processed carriers in the multiple to-be-processed carriers, calculating an average phase difference of the two adjacent to-be-processed carriers;
step S1049, performing phase difference compensation on the two adjacent to-be-processed carriers based on the average phase difference, so that the two adjacent to-be-processed carriers are equivalent to two adjacent subcarriers in the same bandwidth.
Therefore, by utilizing the characteristic that the higher the signal-to-noise ratio (or the better the correlation matrix), the higher the channel estimation accuracy, when the order is greater than the second order, the influence of the random phase difference on the preferred channel estimation result is eliminated by performing phase difference compensation on the adjacent to-be-processed carriers, and the channel estimation accuracy is further improved.
In this embodiment, when channel estimation is performed across multiple carriers, frequency domain filtering may be performed across adjacent carriers. When the order is greater than the second order, it can be considered that the requirement of the current channel estimation on the accuracy is relatively high, and the original channel estimation results of the carriers to be processed need to be combined after being preprocessed.
Specifically, since the bandwidth of each to-be-processed carrier in the narrowband carrier system is very small, such as 25KHz, a plurality of adjacent to-be-processed carriers have a very high probability of being located within the coherence bandwidth, and therefore, it is very beneficial to perform frequency domain filtering across a plurality of adjacent to-be-processed carriers.
Further, although each to-be-processed carrier experiences the same time-domain Radio channel, there may still be a random phase difference between each to-be-processed carrier, for example, a random phase difference caused by Radio Frequency (RF) of a transmitter and a receiver. Thus, channel estimation cannot be done directly, or filtering across multiple carriers to be processed directly.
Further, by performing the step S1048 and the step S1049, a phase difference of Reference Signal (RS) Resource Elements (RE) of adjacent carriers to be processed may be eliminated, and then, operations such as estimation and filtering may be performed. For example, channel covariance is estimated, then MMSE filtering is performed, various differences are performed to obtain channel estimates on the data REs, and then phase differences are applied on the channel estimation results. Alternatively, the phase difference may be extracted from the signal received at the data RE, and data demodulation or the like may be performed.
In a specific embodiment, the step S1048 may include the steps of: the two adjacent carriers are respectively a first carrier and a second carrier, and a candidate channel of each subcarrier in an original channel estimation result of the first carrier and a candidate channel of each subcarrier in an original channel estimation result of the second carrier are respectively obtained; for each subcarrier included in the first carrier, calculating a phase difference between the subcarrier and each subcarrier of the second carrier based on a candidate channel associated with the first carrier; and determining the average value of all the calculated phase differences as the average phase difference.
For example, since the bandwidth of a single to-be-processed carrier is only 25KHz, frequency domain channels experienced by the first carrier and the second carrier are almost the same, and therefore, after the RS RE of the first carrier and the RS RE of the second carrier are estimated by using a Least square method (LS), the LS estimation may be divided at each corresponding RS position to obtain a phase difference between each corresponding RS position. Further, all the obtained phase differences are averaged to obtain the average phase difference.
In one variation, the RS REs of the first carrier may be estimated by using LS to obtain an original channel estimation result of the first carrier. Similarly, the original channel estimation result of the second carrier can be obtained based on the LS estimation. Further, the original channel estimation results of all RS REs in a carrier may be averaged, and the average channel estimation results of the first carrier and the second carrier may be divided to obtain the average phase difference.
Thus, the original channel estimation results after the plurality of pre-processings obtained by performing the phase difference compensation can be equivalent to the channel estimation results of the plurality of subcarriers in the same carrier. Equivalently, 2 carriers to be processed respectively containing 6 subcarriers can be equivalent to one carrier to be processed containing 12 subcarriers, and since the 2 carriers to be processed contain four pilot signals in total, four-order MMSE operation becomes possible, and further the accuracy of channel estimation is effectively improved.
In a specific embodiment, the step S105 may include the steps of: and determining the average value of the plurality of preprocessed original channel estimation results as the preferred channel estimation result.
In a variation, the step S105 may include the steps of: and carrying out weighted summation on the plurality of preprocessed original channel estimation results to obtain the optimal channel estimation result.
Specifically, the weight for performing the weighted summation may be determined by performing MMSE calculation on each of the preprocessed original channel estimation results.
In one implementation, in the step S105, in performing channel estimation, frequency domain filtering may be constrained within a single to-be-processed carrier.
In particular, signal statistics such as channel correlation, covariance, etc. may be obtained by averaging the raw channel estimates for the multiple pending carriers, and the resulting preferred channel estimate may be more accurate than the raw channel estimates based on a single pending carrier.
Further, the preferred channel estimation results over multiple frames may be combined to further improve accuracy.
Further, the frequency domain filtering for each to-be-processed carrier may be performed by using the prior art, which is not described herein again.
For example, for each carrier to be processed with a bandwidth of 25KHz, an original channel estimation result of the carrier to be processed may be obtained, and for any two adjacent carriers to be processed, the two carriers to be processed may be equivalent to two adjacent subcarriers in the same carrier. Furthermore, by simulating the existing channel estimation method, the original channel estimation results of the two adjacent carriers to be processed can be combined by using the MMSE principle based on the second-order statistical characteristics to obtain the preferred channel estimation result.
In one implementation, the original channel estimation result may be a channel estimation result of a subcarrier having a pilot signal in a corresponding to-be-processed carrier.
In particular, the channel estimation mode may include the channel estimation algorithm when the channel estimation mode indicates that no cross-carrier estimation is to be performed.
Correspondingly, the channel estimation method of this embodiment may further include the steps of: and performing channel estimation on the subcarriers without pilot signals in the to-be-processed carriers by adopting a channel estimation algorithm included in the channel estimation mode and the original channel estimation result to obtain the preferred channel estimation result.
Therefore, when the original channel estimation result indicates that cross-carrier fusion is not required, such as when the signal-to-noise ratio is high or the coherence characteristic is narrow, the original channel estimation (obtained by performing step S101) may be performed on the position of the pilot signal, and then channel estimation of other subcarriers without pilot signals may be performed according to the original channel estimation, so as to obtain the channel estimation result of the narrowband carrier aggregation system.
Therefore, by adopting the scheme of the embodiment, the channel estimation precision of the narrowband carrier aggregation system can be effectively improved, and the demodulation performance is optimized.
Specifically, whether cross-carrier fusion is required or not is determined according to the channel condition of the carrier to be processed, so that the finally obtained optimal channel estimation result is more consistent with the wireless signal environment in which the carrier to be processed is currently located, and the channel estimation accuracy can be improved.
Further, when it is determined that cross-carrier fusion needs to be performed, phase differences between multiple carriers that need to be crossed are compensated, so that adjacent carriers can be equal to subcarriers in the same bandwidth, thereby effectively making up for the defect that channel estimation results are poor due to the fact that the number of subcarriers included in a single carrier in a narrowband carrier aggregation system is too small, and making it possible to perform channel estimation by using multiple carriers.
Fig. 5 is a schematic structural diagram of a channel estimation apparatus for a narrowband carrier aggregation system according to an embodiment of the present invention. Those skilled in the art understand that the channel estimation apparatus 5 for narrowband carrier aggregation system (hereinafter referred to as the channel estimation apparatus 5) described in this embodiment may be used to implement the method solutions described in the embodiments shown in fig. 1 to fig. 4.
Specifically, the channel estimation apparatus 5 according to this embodiment may include: an obtaining module 51, configured to obtain an original channel estimation result of each to-be-processed carrier in the narrowband carrier aggregation system; a first determining module 52, configured to determine, for each to-be-processed carrier, a channel estimation mode at least according to a channel condition of the to-be-processed carrier, where the channel estimation mode is used to indicate whether to perform cross-carrier estimation, and when indicating to perform cross-carrier estimation, the channel estimation mode includes the number of cross-carriers and a channel estimation algorithm; a second determining module 53, configured to determine, when the channel estimation mode indicates to perform cross-carrier estimation, multiple to-be-processed carriers to be cross-carrier estimated according to a position of the to-be-processed carrier in the narrowband carrier aggregation system and a number of cross-carriers included in the channel estimation mode; a compensation module 54, configured to perform preprocessing on original channel estimation results of the multiple to-be-processed carriers according to the channel estimation mode, so as to estimate and compensate a phase difference between adjacent to-be-processed carriers in the multiple to-be-processed carriers; and a processing module 55, configured to obtain a preferred channel estimation result based on a combination of the plurality of preprocessed original channel estimation results.
For more details of the operation principle and the operation mode of the channel estimation device 5, reference may be made to the related descriptions in fig. 1 to fig. 4, which are not repeated herein.
Further, the embodiment of the present invention further discloses a storage medium, on which computer instructions are stored, and when the computer instructions are executed, the method technical solution described in the embodiments shown in fig. 1 to fig. 4 is executed. Preferably, the storage medium may include a computer-readable storage medium such as a non-volatile (non-volatile) memory or a non-transitory (non-transient) memory. The storage medium may include ROM, RAM, magnetic or optical disks, etc.
Further, an embodiment of the present invention further discloses a terminal, which includes a memory and a processor, where the memory stores a computer instruction capable of running on the processor, and the processor executes the method technical solution described in the embodiments shown in fig. 1 to 4 when running the computer instruction. Preferably, the terminal may be a 5G user terminal.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (13)
1. A channel estimation method for a narrowband carrier aggregation system, comprising:
acquiring an original channel estimation result of each carrier to be processed in the narrow-band carrier aggregation system;
for each carrier to be processed, determining a channel estimation mode at least according to the channel condition of the carrier to be processed, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm;
when the channel estimation mode indicates to perform cross-carrier estimation, determining a plurality of to-be-processed carriers to be cross-carrier estimated according to the position of the to-be-processed carriers in the narrowband carrier aggregation system and the number of cross-carriers included in the channel estimation mode;
preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed;
and obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results.
2. The channel estimation method according to claim 1, wherein the raw channel estimation result is a channel estimation result of a subcarrier with a pilot signal in a corresponding to-be-processed carrier, and when the channel estimation mode indicates that no cross-carrier estimation is performed, the channel estimation mode includes the channel estimation algorithm, and the channel estimation method further includes:
and performing channel estimation on the subcarriers without pilot signals in the to-be-processed carriers by adopting a channel estimation algorithm included in the channel estimation mode and the original channel estimation result to obtain the preferred channel estimation result.
3. The channel estimation method according to claim 1 or 2, characterized in that the channel estimation algorithm comprises: and MMSE, wherein the order of the MMSE is determined according to a preset correlation matrix, the preset correlation matrix is obtained based on the correlation matrix of the carrier to be processed, or the preset correlation matrix is obtained by averaging based on the correlation matrix of the carrier to be processed and the correlation matrix of the adjacent carrier to be processed.
4. The channel estimation method of claim 1, wherein the channel condition comprises: frequency selectivity; signal to noise ratio.
5. The channel estimation method according to claim 1, wherein the determining a channel estimation mode according to at least the channel condition of the to-be-processed carrier comprises:
determining a channel correlation estimation result according to the channel condition of the to-be-processed carrier and the channel condition of the adjacent to-be-processed carrier, wherein the channel correlation estimation result comprises a coherent bandwidth;
and determining the channel estimation mode at least according to the channel correlation estimation result.
6. The channel estimation method of claim 1, wherein the channel estimation algorithm comprises: MMSE; the channel condition comprises a signal-to-noise ratio; the determining a channel estimation mode at least according to the channel condition of the to-be-processed carrier comprises:
and determining the order of MMSE according to the signal-to-noise ratio.
7. The channel estimation method according to claim 6, wherein the pre-processing the raw channel estimation results of the plurality of to-be-processed carriers according to the channel estimation mode to estimate and compensate for the phase difference between adjacent to-be-processed carriers of the plurality of to-be-processed carriers comprises:
when the order of the MMSE is second order, determining the phase difference to be zero;
and for each to-be-processed carrier in the plurality of to-be-processed carriers, taking the original channel estimation result of the to-be-processed carrier as a corresponding preprocessed original channel estimation result.
8. The channel estimation method according to claim 6, wherein the pre-processing the raw channel estimation results of the plurality of to-be-processed carriers according to the channel estimation mode to estimate and compensate for the phase difference between adjacent to-be-processed carriers of the plurality of to-be-processed carriers comprises:
when the order of the MMSE is greater than the second order, calculating the average phase difference of two adjacent to-be-processed carriers in the plurality of to-be-processed carriers;
and performing phase difference compensation on the two adjacent to-be-processed carriers based on the average phase difference so as to enable the two adjacent to-be-processed carriers to be equivalent to two adjacent subcarriers in the same bandwidth.
9. The channel estimation method according to claim 8, wherein said calculating, for each two adjacent to-be-processed carriers of the plurality of to-be-processed carriers, an average phase difference of the two adjacent to-be-processed carriers comprises:
the two adjacent carriers to be processed are respectively a first carrier and a second carrier, and a candidate channel of each subcarrier in an original channel estimation result of the first carrier and a candidate channel of each subcarrier in an original channel estimation result of the second carrier are respectively obtained;
for each subcarrier included in the first carrier, calculating a phase difference between the subcarrier and each subcarrier of the second carrier based on a candidate channel associated with the first carrier;
and determining the average value of all the calculated phase differences as the average phase difference.
10. The channel estimation method of claim 1, wherein the combining the plurality of preprocessed original channel estimation results to obtain the preferred channel estimation result comprises:
determining an average value of the plurality of preprocessed original channel estimation results as the preferred channel estimation result; alternatively, the first and second electrodes may be,
and carrying out weighted summation on the plurality of preprocessed original channel estimation results to obtain the optimal channel estimation result.
11. A channel estimation apparatus for a narrowband carrier aggregation system, comprising:
the acquisition module is used for acquiring the original channel estimation result of each carrier to be processed in the narrowband carrier aggregation system;
the first determining module is used for determining a channel estimation mode according to the channel condition of each to-be-processed carrier at least, wherein the channel estimation mode is used for indicating whether cross-carrier estimation is carried out, and when the cross-carrier estimation is indicated, the channel estimation mode comprises the number of cross-carriers and a channel estimation algorithm;
a second determining module, configured to determine, when the channel estimation mode indicates to perform cross-carrier estimation, a plurality of to-be-processed carriers to be estimated in a cross-carrier manner according to a position of the to-be-processed carrier in the narrowband carrier aggregation system and a number of cross-carriers included in the channel estimation mode;
the compensation module is used for preprocessing the original channel estimation results of the multiple carriers to be processed according to the channel estimation mode so as to estimate and compensate the phase difference between adjacent carriers to be processed in the multiple carriers to be processed;
and the processing module is used for obtaining a preferred channel estimation result based on the combination of a plurality of preprocessed original channel estimation results.
12. A storage medium having stored thereon computer instructions, wherein said computer instructions when executed perform the steps of the method of claims 1 to 10.
13. A terminal comprising a memory and a processor, the memory having stored thereon computer instructions executable on the processor, wherein the processor, when executing the computer instructions, performs the steps of the method of any one of claims 1 to 10.
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