CN102088425A - Method, apparatus and system for channel estimation and pilot insertion in MIMO system - Google Patents
Method, apparatus and system for channel estimation and pilot insertion in MIMO system Download PDFInfo
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Abstract
The present invention discloses a method, an apparatus and a system for channel estimation and pilot insertion in an MIMO system, wherein the method comprises the steps of: determining whether the number of the symbols in an MIMO area of a receiving end is integral multiple of 4; respectively extracting the pilot subcarriers from the symbol portion which is integral multiple of 4 and the remaining symbol portion which is non-integral multiple of 4, to perform the channel estimation; in a transmitting terminal, correspondingly determining whether the number of the symbols in an MIMO area of the transmitting terminal is integral multiple of 4; and respectively inserting pilot subcarriers into the symbol portion which is integral multiple of 4 and the remaining symbol portion which is non-integral multiple of 4. The method for channel estimation and pilot insertion of the invention can flexibly realize the pilot subcarrier insertion and channel estimation by using the pilot subcarriers when the downlink MIMO system area is configured with any quantity of symbols, thereby overcoming the restriction on the channel estimation from the number of symbols, enhancing the flexibility of the frame configuration in a downlink MIMO system, and increasing the utilization rate of the subcarriers.
Description
Technical Field
The present invention relates to the field of wireless communications, and in particular, to a method, an apparatus, and a system for channel estimation and pilot insertion in a wireless Multiple Input Multiple Output (MIMO) communication system.
Background
In a wireless communication system, channel estimation is particularly important in the wireless communication system because the propagation path between the transmitter and the receiver is very complex, the transmission quality of signals on a wireless channel is affected, and the wireless channel is not fixed and predictable as a wired channel but has great randomness, which often causes amplitude, phase and frequency distortion of received signals, and affects the performance of the wireless communication system. Channel estimation may be defined as a process of feasibility study describing the impact of a physical channel on an input signal.
In order to ensure the accuracy of signal transmission in a wireless communication system, multiple transmitting antennas and multiple receiving antennas, i.e., an MIMO system, are usually used to transmit data to form multiple MIMO channels, and each MIMO channel needs to be obtained for channel estimation in order to distinguish different users and improve system performance. In general, a downlink channel estimation method inserts pilot subcarriers into a downlink, and a receiving end estimates a channel response of an entire link according to a received value obtained by the pilot subcarriers at corresponding positions.
According to the IEEE802.16 protocol, in a downlink Orthogonal Frequency Division Multiplexing (OFDM) system using a MIMO system, a minimum processing unit carrying information is defined as one cluster, each cluster is composed of two symbols and one Frequency, and each symbol has a structure of 2 pilot subcarriers and 12 data subcarriers per Frequency, and each two symbols form one cycle. As shown in fig. 1, positions of 14 subcarriers are sequentially represented as [ 6, -5, -4,. 5, 6, 7 ] from left to right, wherein an open circle represents a data subcarrier, an open triangle represents a pilot subcarrier, a first row is a subcarrier of an even symbol, and the pilot subcarrier is at a position of [ 2, 2 ]; the position of the pilot subcarrier of the second row cardinal number symbol is (6, 6). The channel estimation of the downlink data subcarriers is implemented by using 4 pilot subcarriers in a cluster with 2 symbols having the same position in frequency to perform linear fitting, and accordingly, the 4 pilot subcarriers need to be extracted from the 2 symbols at the transmitting end. In the MIMO system, in order to distinguish different transmitting antennas, pilot subcarriers of each antenna are halved compared with the structure of a non-MIMO system, and the currently commonly used MIMO system adopts two transmitting antennas, and according to the protocol, channel estimation needs 4 pilot subcarriers to perform linear fitting, and correspondingly, 4 pilot subcarriers need to be extracted at a transmitting end, so that channel estimation in the MIMO system with two transmitting antennas is realized by taking four symbols as a cycle. As shown in fig. 2, where circles represent data subcarriers, open triangles represent pilot subcarriers on a first antenna, and solid triangles represent pilot subcarriers on a second antenna. And finding 2 cluster of the same position frequency in four adjacent symbols, extracting 4 pilot frequency sub-carriers from the same transmitting antenna, and further carrying out channel estimation. In the MIMO system, since the determination of the channel estimation value needs 4 symbols, the ratio of the whole frame of the system is limited, that is, when the number of the region symbols in the MIMO system is a multiple of 4, the region symbols are an effective data region, when the number of the MIMO region symbols is not an integer multiple of 4, the subcarriers cannot be fully utilized, and if a simple averaging method is adopted for channel estimation in the redundant symbols, the error rate is increased.
Disclosure of Invention
In view of the above, a primary object of the present invention is to provide a method, an apparatus and a system for extracting pilot subcarriers by using all region symbols and performing channel estimation using the pilot subcarriers when the number of MIMO region symbols is a non-integer multiple of 4 in a downlink MIMO system.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a method for estimating channel in MIMO system includes determining whether number of symbols in MIMO region at receiving end is integer multiple of 4;
for the integral multiple symbol part of 4, every 4 symbols are a cycle, respectively extracting the pilot frequency subcarrier of each symbol in each cycle, and totally extracting 4 pilot frequency subcarriers for determining a channel estimation value;
and for the symbol part which is not integral multiple of 4, extracting pilot subcarriers of the remaining n symbols and supplementing the missing 4-n pilot subcarriers to form 4 pilot subcarriers for determining the channel estimation value, wherein n is the number of the symbols which is not integral multiple of 4.
Further, the method for supplementing the missing pilot subcarriers comprises: and for the remaining n symbols, extracting n pilot subcarriers of the transmitting antenna, determining the number of the missing pilot subcarriers to be 4-n, finding the missing 4-n pilot subcarriers at the positions of the pilot subcarriers in 4 adjacent symbols before the n symbols, and supplementing the missing 4-n pilot subcarriers into the n pilot subcarriers to form 4 pilot subcarriers for determining the channel estimation value.
Further, the specific method for supplementing the missing pilot subcarriers includes:
if the number of the symbols in the MIMO area is divided by 4 and the number of the added symbols is 1, the pilot subcarriers of the last 3 symbols of the 4 symbol groups are supplemented;
the number of the symbols of the MIMO area divided by 4 is more than 2, and then the pilot frequency sub-carriers of the last 2 symbols of the 4 symbol groups are supplemented;
and if the number of the symbols of the MIMO area is divided by 4 and the number of the added symbols is 3, the pilot subcarriers of the last 1 symbol of the 4 symbol group are supplemented.
Further, the specific method for supplementing the missing pilot subcarriers further includes:
the sequence of the 4 pilot subcarriers formed after the supplementation is the same as the sequence of the pilot subcarriers of the 4 adjacent symbols before the remaining n symbols.
Further, the method for determining the channel estimation value comprises the following steps:
the channel estimation value is calculated by using the pilot frequency subcarrier value determined by the directly extracted 4 pilot frequency subcarriers or the supplemented 4 pilot frequency subcarriers, and the specific calculation method comprises the following steps:
wherein
Means 4 pilot subcarrier values, i ═ 0, 1, 2, 3]。
In order to achieve the above object, the present invention further provides a method for inserting pilot subcarriers in a MIMO system, the method including determining whether the number of symbols in a MIMO region at a transmitting end is an integer multiple of 4;
for the symbol part of integral multiple of 4, every 4 symbols are a cycle, and 4 pilot subcarriers are respectively inserted for 4 symbols in each cycle;
for the rest of the symbol parts which are not integral multiples of 4, inserting pilot frequency sub-carriers in sequence according to the positions of the previous 4 adjacent symbols for inserting the pilot frequency sub-carriers;
further, the pilot subcarriers are used for channel estimation at the receiving end.
A device for estimating channels in an MIMO system comprises a receiving end symbol number determining module, a pilot frequency subcarrier extracting module, a pilot frequency subcarrier supplementing module and a channel estimation value determining module; wherein,
the receiving end symbol number determining module is used for determining the symbol number characteristics of the MIMO area of the receiving end;
a pilot subcarrier extracting module, configured to extract pilot subcarriers of transmitting antennas in the MIMO region symbol set;
a pilot subcarrier supplementing module for supplementing the missing pilot subcarriers for the residual symbol group;
and the channel estimation value determining module is used for carrying out channel estimation according to the pilot frequency subcarrier value.
Further, the receiving-end symbol number determining module is configured to divide the symbols of the MIMO region into an integer multiple of 4 and an integer multiple of non-4 according to the number of the symbols, notify the pilot subcarrier extracting module to extract pilot subcarriers for the symbols of the integer multiple of 4, extract pilot subcarriers for the symbols of the integer multiple of non-4, and notify the pilot subcarrier supplementing module to supplement the missing pilot subcarriers for the symbols of the integer multiple of non-4.
Further, the pilot subcarrier extraction module is configured to extract pilot subcarriers of the transmitting antennas in the integer multiple of 4 symbols, or extract pilot subcarriers of the transmitting antennas in the non-integer multiple of 4 symbols, and notify the pilot subcarrier supplementation module of a result of extracting pilot subcarriers for the non-integer multiple of 4 symbols.
Further, the pilot subcarrier complementing module is configured to determine the number of missing pilot subcarriers according to a result that the pilot subcarrier extracting module notifies that the symbol of the integral multiple part of the non-4 is the extracted pilot subcarrier, find the missing pilot subcarriers at corresponding positions of the previous 4 adjacent symbols, and complement the pilot subcarriers for the symbol of the integral multiple part of the non-4.
Further, the channel estimation value determination module is configured to calculate a channel estimation value according to the pilot subcarrier value extracted by the pilot subcarrier extraction module or supplemented by the pilot subcarrier supplementation module, and complete channel estimation at the receiving end.
A device for inserting pilot frequency in MIMO system comprises a transmitting end symbol number determining module and a pilot frequency subcarrier inserting module; wherein,
the sending end symbol number determining module is used for determining the symbol number characteristics of the MIMO area of the sending end;
and the pilot frequency subcarrier inserting module is used for inserting the pilot frequency into the corresponding symbol of the sending end.
Further, the transmitting-end symbol number determining module is configured to determine whether the number of symbols in the MIMO region at the transmitting end is an integer multiple of 4, divide the symbols in the MIMO region into an integer multiple of 4 and an integer multiple of non-4 according to the number of the symbols, and notify the pilot subcarrier inserting module to insert pilot subcarriers for the two symbols respectively.
Further, the pilot subcarrier insertion module is configured to insert pilot subcarriers for the symbols of the MIMO region:
for the symbol part of integral multiple of 4, inserting pilot frequency sub-carriers for each symbol for every 4 symbols, and totally inserting 4 pilot frequency sub-carriers;
and for the rest non-4 integral multiple symbol parts, inserting pilot frequency sub-carriers according to the method of inserting the pilot frequency sub-carriers in the previous 4 adjacent symbols.
A MIMO system comprising at least the pilot subcarrier insertion apparatus of any of claims 7-14 and a channel estimation apparatus; the device for inserting the pilot frequency subcarrier is used for inserting the pilot frequency subcarrier into the symbol of the MIMO area of the sending end, and after the symbol inserted with the pilot frequency subcarrier is sent to the receiving end, the channel estimation device extracts the pilot frequency subcarrier of the corresponding symbol in the MIMO area to determine a channel estimation value, so that channel estimation is realized.
It can be seen from the scheme provided by the present invention that in the MIMO system, any number of symbols can be configured in the downlink MIMO system region, and pilot subcarrier insertion and channel estimation using the pilot subcarrier can be flexibly implemented under the configuration of any number of symbols, thereby overcoming the limitation of the number of symbols on channel estimation, enhancing the flexibility of frame configuration in the downlink MIMO system, and improving the subcarrier utilization rate. Through simulation comparison, the scheme provided by the invention has high accuracy in channel estimation and can not cause system performance reduction.
Drawings
Fig. 1 is a schematic structural diagram of a downlink frame in a non-MIMO system;
fig. 2 is a schematic structural diagram of a downlink frame in the MIMO system;
FIG. 3 is a flowchart of a method for a receiving end to perform channel estimation according to the present invention;
FIG. 4 is a flowchart of a method for inserting pilot subcarriers at a transmitting end according to the present invention;
FIG. 5 is a diagram of an embodiment of supplementing pilot subcarriers in a downlink frame of a MIMO system according to the method of the present invention;
FIG. 6 is a schematic diagram of an apparatus for channel estimation by a receiving end according to the present invention;
fig. 7 is a schematic diagram of an apparatus for inserting pilot subcarriers at a transmitting end in the present invention.
Detailed Description
In the MIMO system, according to the requirement of IEEE802.16 protocol, the period of the downlink frame is short, and the time interval between adjacent symbols is small, so that the channel estimation values of adjacent symbols under the same frequency can be used in the downlink frame to approximate the channel estimation replacing the symbol, and since the channel estimation values between different symbols under the same frequency are used to make mutual approximation, the frequency selective fading of the channel does not affect the performance of the approximation method. Accordingly, before performing channel estimation, the transmitting end inserts pilot subcarriers for symbols of the MIMO region for performing channel estimation.
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Fig. 3 is a flowchart of a method for a receiving end to perform channel estimation, as shown in fig. 3, including:
step 300: and the receiving end carries out sub-carrier demapping.
Step 301: determining the number of symbols of the MIMO area, wherein in the step, the number of symbols of the MIMO area needs to be determined, and different processing is carried out according to whether the number of symbols of the MIMO area is integral multiple of 4; when the number of symbols is an integer multiple of 4, performing step 302; when the number of symbols is a non-integer multiple of 4, step 303 is performed.
Step 302: according to the judgment of step 301, when the number of symbols in the MIMO region is an integer multiple of 4, the pilot subcarriers are extracted in one cycle according to 4 symbols for channel estimation, and in this step, a specific method for determining the channel estimation value is as follows:
the receiving end estimates the channel response of the whole link according to the received value obtained after inserting the pilot frequency sub-carrier in the downlink, and particularly, assumes a cluster
Is the channel frequency response at subcarrier k, where-6 ≦ k ≦ 7. P is the position of all pilot subcarriers in one cluster. Let P [ -6, -2, 2, 6]. By means of linear fitting, the channel estimation value of each position data subcarrier should be:
whereinRefers to an estimated value obtained by 4 pilot subcarriers, i ═ 0, 1, 2, 3]。
Step 303: according to the judgment of step 301, when the number of symbols in the MIMO region is a non-integer multiple of 4, the integer multiple of 4 symbols is used to extract pilot subcarriers for channel estimation according to 4 symbols in one cycle, the specific channel estimation method is the same as the channel estimation method in step 302, and the remaining 4 non-integer multiple of symbols are processed in step 304.
Step 304: it is determined that several symbols remain after the number of symbols of the MIMO region is divided by 4, and the process of step 305 is performed according to the number of remaining symbols. The missing number of symbols complements the missing pilot subcarriers,
step 305: supplementing the missing pilot subcarriers according to the remaining symbol number determined in step 304, which includes the following specific cases:
(1) if the number of the symbols of the MIMO area is divided by 4 and the number of the symbols is more than 1, supplementing the pilot subcarriers of the last 3 symbols of the previous 4 adjacent symbols, wherein the supplemented positions are the same as the positions of the pilot subcarriers of the previous 4 symbol groups;
(2) if the number of the symbols of the MIMO area is divided by 4 and the number of the symbols is more than 2, the pilot subcarriers of the last 2 symbols of the previous 4 adjacent symbols are supplemented, and the supplemented positions are the same as the positions of the pilot subcarriers of the previous 4 symbol groups;
(3) and if the number of the symbols of the MIMO area is more than 3 after being divided by 4, the pilot subcarriers of the last 1 symbol of the previous 4 adjacent symbols are supplemented, and the supplemented positions are the same as the positions of the pilot subcarriers of the previous 4 symbol groups.
Step 306: the channel estimation value is determined by using 4 pilot subcarriers, and the specific channel estimation method is the same as the channel estimation method in step 302.
Step 307: and combining the multi-antenna channel estimation values to complete the channel estimation of the receiving end in the MIMO system.
Fig. 4 is a flowchart of a method for inserting pilot subcarriers at a transmitting end in the present invention, as shown in fig. 4, including:
step 400: and subcarrier mapping, in this step, mapping the coded signal of the transmitting end in the MIMO system to the subcarrier modulated by the corresponding multicarrier.
Step 401: determining the number of symbols of the MIMO area, wherein in the step, the number of symbols of the MIMO area needs to be determined, and different processing is carried out according to whether the number of symbols of the MIMO area is integral multiple of 4; when the number of symbols is an integer multiple of 4, go to step 402; when the number of symbols is a non-integer multiple of 4, step 403 is performed.
Step 402: according to the judgment of step 401, when the number of symbols of the MIMO region is an integer multiple of 4, 4 pilot subcarriers are inserted for one cycle every 4 symbols.
Step 403: when the number of symbols in the MIMO region is a non-integer multiple of 4, as determined in step 401, 4 pilot subcarriers are inserted into the integer multiple of 4 symbol portions for one cycle of 4 symbols, and the processing of step 404 is performed on the remaining integer multiple of non-4 symbol portions.
Step 404: inserting pilot frequency sub-carriers for the rest non-4 integral multiple symbol parts in sequence, wherein in the step, the method for inserting the pilot frequency sub-carriers comprises the following steps:
and inserting pilot frequency sub-carriers for the rest symbols in the step in sequence according to the positions of inserting the pilot frequency sub-carriers into the previous 4 adjacent symbols.
Step 405: IFFT, in this step, after inserting the pilot subcarriers, signal modulation is performed through fourier transform, which is not used to limit the present invention.
Fig. 5 is a schematic diagram of an embodiment of supplementing pilot subcarriers in a downlink frame of a MIMO system according to the method of the present invention, where each row represents the structure of one symbol, and a circle represents a data subcarrier, an open triangle represents a pilot subcarrier on a first antenna, and a solid triangle represents a pilot subcarrier on a second antenna, as shown in fig. 5. In this embodiment, there are 6 symbols in total, the number of symbols is a non-integral multiple of 4, and the number of symbols in the first row to the sixth row is set to be 4K, 4K +1, 4K +2, 4K +3, 4K +4, and 4K +5 in sequence, according to the channel estimation approximation method of the present invention, the 4K, 4K +1, 4K +2, and 4K +3 symbols constitute a complete 4-symbol cycle, and the corresponding pilot subcarriers are directly extracted for channel estimation, and for the 4K +4 and 4K +5 symbols, after the pilot subcarriers of the corresponding transmitting antennas are extracted, the 4K +2 and 4K +3 symbols are supplemented to the rear of the pilot subcarriers to constitute 4 pilot subcarriers, so as to perform channel estimation. In a specific implementation, since the channel estimation is mainly calculated by the pilot subcarrier value, the pilot subcarrier of each symbol can be directly extracted without complementing the data subcarrier part. As shown in fig. 5, for the 4K +4 and 4K +5 symbols, the 4 pilot subcarriers indicated by the arrows can be directly extracted for channel estimation.
Fig. 6 is a schematic diagram of a device for performing channel estimation by a receiving end in the present invention, and as shown in fig. 6, the device for performing channel estimation by the receiving end in the present invention at least includes:
a receiving end symbol number determining module 600, configured to determine a symbol number characteristic of a receiving end MIMO region;
the module is specifically configured to divide symbols of the MIMO region into two parts, namely an integer multiple of 4 and an integer multiple of non-4, according to the number of the symbols, notify the pilot subcarrier extraction module to extract pilot subcarriers for the symbols of the integer multiple of 4, extract pilot subcarriers for the symbols of the integer multiple of non-4, and notify the pilot subcarrier supplement module to supplement missing pilot subcarriers for the symbols of the integer multiple of non-4.
A pilot subcarrier extracting module 601, configured to extract pilot subcarriers of transmitting antennas in the MIMO region symbol set;
the module is specifically configured to extract pilot subcarriers of the transmitting antennas in the integer multiple of 4 symbols, or extract pilot subcarriers of the transmitting antennas in the non-4 integer multiple of symbols, and notify the pilot subcarrier complementing module of the result of extracting the pilot subcarriers for the non-4 integer multiple of symbols.
A pilot subcarrier complementing module 602, configured to complement the remaining symbol group with missing pilot subcarriers;
the module is specifically configured to determine the number of missing pilot subcarriers according to the result of extracting the pilot subcarriers from the symbols that are not integer multiples of 4 notified by the pilot subcarrier extraction module, find the missing pilot subcarriers at the corresponding positions of the preceding 4 adjacent symbols, and supplement the pilot subcarriers for the symbols that are not integer multiples of 4.
A channel estimation value determining module 603, configured to perform channel estimation according to the pilot subcarrier value;
the module is specifically used for calculating a channel estimation value according to a pilot subcarrier value extracted by the pilot subcarrier extraction module or supplemented by the pilot subcarrier supplement module, and finishing channel estimation of a receiving end.
Fig. 7 is a schematic diagram of an apparatus for inserting pilot subcarriers at a transmitting end in the present invention, and as shown in fig. 7, the apparatus for inserting pilot subcarriers at the transmitting end in the present invention at least includes:
a transmitting-end symbol number determining module 700, configured to determine a symbol number characteristic of a transmitting-end MIMO region;
the module is specifically configured to determine whether the number of symbols in the MIMO region at the transmitting end is an integer multiple of 4, divide the symbols in the MIMO region into an integer multiple of 4 and a non-integer multiple of 4 according to the number of the symbols, and notify the pilot subcarrier insertion module to insert pilot subcarriers for the two symbols, respectively.
A pilot subcarrier inserting module 701, configured to insert a pilot in a corresponding symbol at a sending end;
this module is specifically configured to insert pilot subcarriers for the symbols of the MIMO region:
for the symbol part of integral multiple of 4, inserting pilot frequency sub-carriers for each symbol for every 4 symbols, and totally inserting 4 pilot frequency sub-carriers;
and for the rest of the integral multiple symbol parts which are not 4, inserting the pilot subcarriers according to the method of inserting the pilot subcarriers in the previous 4 adjacent symbols.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.
Claims (15)
1. A method for estimating channel in MIMO system is characterized in that, whether the number of symbols in the MIMO area of the receiving end is integer multiple of 4 is determined;
for the integral multiple symbol part of 4, every 4 symbols are a cycle, respectively extracting the pilot frequency subcarrier of each symbol in each cycle, and totally extracting 4 pilot frequency subcarriers for determining a channel estimation value;
and for the symbol part which is not integral multiple of 4, extracting pilot subcarriers of the remaining n symbols and supplementing the missing 4-n pilot subcarriers to form 4 pilot subcarriers for determining the channel estimation value, wherein n is the number of the symbols which is not integral multiple of 4.
2. The method of channel estimation according to claim 1, wherein the method of supplementing the missing pilot subcarriers is: and for the remaining n symbols, extracting n pilot subcarriers of the transmitting antenna, determining the number of the missing pilot subcarriers to be 4-n, finding the missing 4-n pilot subcarriers at the positions of the pilot subcarriers in 4 adjacent symbols before the n symbols, and supplementing the missing 4-n pilot subcarriers into the n pilot subcarriers to form 4 pilot subcarriers for determining the channel estimation value.
3. The method of channel estimation according to claim 2, wherein the specific method of supplementing the missing pilot subcarriers comprises:
if the number of the symbols in the MIMO area is divided by 4 and the number of the added symbols is 1, the pilot subcarriers of the last 3 symbols of the 4 symbol groups are supplemented;
the number of the symbols of the MIMO area divided by 4 is more than 2, and then the pilot frequency sub-carriers of the last 2 symbols of the 4 symbol groups are supplemented;
and if the number of the symbols of the MIMO area is divided by 4 and the number of the added symbols is 3, the pilot subcarriers of the last 1 symbol of the 4 symbol group are supplemented.
4. The method of channel estimation according to claim 2 or 3, wherein the specific method of supplementing the missing pilot subcarriers further comprises:
the sequence of the 4 pilot subcarriers formed after the supplementation is the same as the sequence of the pilot subcarriers of the 4 adjacent symbols before the remaining n symbols.
5. The method of channel estimation according to claim 1, wherein the method of determining the channel estimation value is:
the channel estimation value is calculated by using the pilot frequency subcarrier value determined by the directly extracted 4 pilot frequency subcarriers or the supplemented 4 pilot frequency subcarriers, and the specific calculation method comprises the following steps:
whereinMeans 4 pilot subcarrier values, i ═ 0, 1, 2, 3]。
6. A method for inserting pilot frequency subcarrier in MIMO system is characterized in that whether the number of symbols of MIMO area at the transmitting end is integral multiple of 4 is determined;
for the symbol part of integral multiple of 4, every 4 symbols are a cycle, and 4 pilot subcarriers are respectively inserted for 4 symbols in each cycle;
for the rest of the symbol parts which are not integral multiples of 4, inserting pilot frequency sub-carriers in sequence according to the positions of the previous 4 adjacent symbols for inserting the pilot frequency sub-carriers;
the pilot subcarriers are used for channel estimation at the receiving end.
7. A device for estimating channels in an MIMO system is characterized by comprising a receiving end symbol number determining module, a pilot frequency subcarrier extracting module, a pilot frequency subcarrier supplementing module and a channel estimation value determining module; wherein,
the receiving end symbol number determining module is used for determining the symbol number characteristics of the MIMO area of the receiving end;
a pilot subcarrier extracting module, configured to extract pilot subcarriers of transmitting antennas in the MIMO region symbol set;
a pilot subcarrier supplementing module for supplementing the missing pilot subcarriers for the residual symbol group;
and the channel estimation value determining module is used for carrying out channel estimation according to the pilot frequency subcarrier value.
8. The apparatus of claim 7, wherein the receiving-end symbol number determining module is configured to divide the symbols of the MIMO region into an integer multiple of 4 and an integer multiple of non-4 according to the number of the symbols, and notify the pilot subcarrier extracting module to extract pilot subcarriers for the integer multiple of 4, extract pilot subcarriers for the integer multiple of non-4, and notify the pilot subcarrier supplementing module to supplement the missing pilot subcarriers for the integer multiple of non-4.
9. The apparatus of claim 7, wherein the pilot subcarrier extraction module is configured to extract pilot subcarriers of transmit antennas in an integer multiple of the 4 symbols or extract pilot subcarriers of transmit antennas in an integer multiple of the non-4 symbols, and notify the pilot subcarrier supplement module of the result of extracting pilot subcarriers for the non-4 integer multiple of the symbols.
10. The apparatus of claim 7, wherein the pilot subcarrier complementing module is configured to determine the number of missing pilot subcarriers according to the result of extracting pilot subcarriers for the integer-times portion of symbols other than 4 notified by the pilot subcarrier extracting module, find the missing pilot subcarriers in the corresponding positions of the previous 4 adjacent symbols, and complement the pilot subcarriers for the integer-times portion of symbols other than 4.
11. The apparatus for channel estimation according to claim 7, wherein the channel estimation value determining module is configured to calculate a channel estimation value according to the pilot subcarrier value extracted by the pilot subcarrier extracting module or supplemented by the pilot subcarrier supplementing module, and complete channel estimation at the receiving end.
12. A device for inserting pilot frequency in MIMO system is characterized in that the device comprises a transmitting end symbol number determining module and a pilot frequency subcarrier inserting module; wherein,
the sending end symbol number determining module is used for determining the symbol number characteristics of the MIMO area of the sending end;
and the pilot frequency subcarrier inserting module is used for inserting the pilot frequency into the corresponding symbol of the sending end.
13. The apparatus for inserting pilot according to claim 12, wherein the transmitting-end symbol number determining module is configured to determine whether the number of symbols in a MIMO region at the transmitting end is an integer multiple of 4, divide the symbols in the MIMO region into an integer multiple of 4 and a non-integer multiple of 4 according to the number of the symbols, and notify the pilot subcarrier inserting module to insert pilot subcarriers for the two symbols respectively.
14. The apparatus for inserting pilot of claim 12, wherein the pilot subcarrier inserting module is configured to insert pilot subcarriers for the symbols of the MIMO region:
for the symbol part of integral multiple of 4, inserting pilot frequency sub-carriers for each symbol for every 4 symbols, and totally inserting 4 pilot frequency sub-carriers;
and for the rest non-4 integral multiple symbol parts, inserting pilot frequency sub-carriers according to the method of inserting the pilot frequency sub-carriers in the previous 4 adjacent symbols.
15. A MIMO system comprising at least the pilot subcarrier inserting apparatus of any of claims 7-14 and a channel estimating apparatus; the device for inserting the pilot frequency subcarrier is used for inserting the pilot frequency subcarrier into the symbol of the MIMO area of the sending end, and after the symbol inserted with the pilot frequency subcarrier is sent to the receiving end, the channel estimation device extracts the pilot frequency subcarrier of the corresponding symbol in the MIMO area to determine a channel estimation value, so that channel estimation is realized.
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| PCT/CN2011/072974 WO2012119337A1 (en) | 2011-03-08 | 2011-04-19 | Method, device and system for estimating channels and inserting pilots in mimo system |
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| CN113839899A (en) * | 2021-10-28 | 2021-12-24 | 中国电子科技集团公司第五十四研究所 | Channel estimation method of MIMO-OFDM system |
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| KR100224863B1 (en) * | 1997-08-20 | 1999-10-15 | 윤종용 | Equalization Methods and Equalizers for OFDM Receivers |
| US8059737B2 (en) * | 2008-06-23 | 2011-11-15 | Mediatek Inc. | OFDM receiver having memory capable of acting in a single-chip mode and a diversity mode |
| JP5274210B2 (en) * | 2008-11-13 | 2013-08-28 | 三菱電機株式会社 | OFDM demodulator |
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| US20060067420A1 (en) * | 2004-09-29 | 2006-03-30 | Alcatel | Multiple input multiple output orthogonal frequency division multiplexing mobile comminication system and channel estimation method |
| CN1889554A (en) * | 2005-06-27 | 2007-01-03 | 华为技术有限公司 | Pilot frequency transfer method |
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| CN113839899B (en) * | 2021-10-28 | 2022-08-02 | 中国电子科技集团公司第五十四研究所 | Channel estimation method of MIMO-OFDM system |
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