WO2011116606A1 - 正交频分复用系统中的信道估计方法及装置 - Google Patents
正交频分复用系统中的信道估计方法及装置 Download PDFInfo
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- WO2011116606A1 WO2011116606A1 PCT/CN2010/078354 CN2010078354W WO2011116606A1 WO 2011116606 A1 WO2011116606 A1 WO 2011116606A1 CN 2010078354 W CN2010078354 W CN 2010078354W WO 2011116606 A1 WO2011116606 A1 WO 2011116606A1
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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
- H04L25/0204—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
- H04L25/022—Channel estimation of frequency response
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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
- H04L25/0224—Channel estimation using sounding signals
-
- 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
- H04L25/0224—Channel estimation using sounding signals
- H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
- H04L25/023—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols
- H04L25/0232—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols by interpolation between sounding signals
- H04L25/0234—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols by interpolation between sounding signals by non-linear interpolation
-
- 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
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators
- H04L27/2633—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators using partial FFTs
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0014—Three-dimensional division
- H04L5/0023—Time-frequency-space
Definitions
- the present invention relates to channel estimation techniques, and more particularly to a channel estimation method and apparatus in an orthogonal frequency division multiplexing system. Background technique
- channel estimation is essential. At the receiving end, whether it is signal detection or measurement of various parameters, it is necessary to first estimate the channel first, and then use the estimated channel coefficients for signal detection and the like.
- LTE Long Term Evolution
- OFDMA Orthogonal Frequency Division Multiple Access
- the OFDM (Orthogonal Frequency Division Multiplexing) system channel estimation is theoretically a 2D Wiener estimator as the best estimator, and the estimator can be used for channel estimation for all subcarriers of the OFDM system.
- the frequency domain interpolation after the first time domain interpolation; the channel estimation for each OFDM symbol can be dynamically calculated by three times the frequency domain interpolation; this method has a very high computational complexity due to too many frequency domain interpolation times.
- Time domain interpolation after frequency domain interpolation 6 times upper frequency domain interpolation method can be used for OFDM symbols including RS (reference signal), and interpolation results are used to calculate OFDM symbols without RS Channel estimation.
- RS reference signal
- the disadvantages of this method are: on the one hand, the result of frequency domain interpolation is preserved, and the storage amount is large; on the other hand, the frequency domain interpolation method uses 6 times of the upper-like method, and the channel estimation performance loss is large, especially in frequency selection. Under strong channel conditions. Summary of the invention
- One of the objects of the present invention is to provide a channel estimation method and apparatus in an orthogonal frequency division multiplexing system, which can realize storage sharing and save storage.
- the invention provides a channel estimation method in an orthogonal frequency division multiplexing system, comprising the steps of:
- step ⁇ Determine whether the channel estimation for the packet is completed, and if yes, end; otherwise, return to step ⁇ , the channel estimation includes the following steps:
- a second time domain interpolation is performed, and channel coefficients of the OFDM symbol without the reference signal are calculated using the channel coefficients on the OFDM symbol including the reference signal, thereby obtaining channel coefficients on all OFDM symbols.
- the channel coefficient calculation of the resource element includes the steps of:
- the information of the resource element is distinguished, and the channel coefficient of the resource element is calculated according to the information of the resource element.
- the channel estimate is based on the formula:
- j AT 3 ⁇ 4 / > AT SymDL is the number of OFDM symbols in a single subframe
- 'SyleDL- ⁇ SymDL denotes the k-th subcarrier channel estimation value of the current subframe OFDM symbol before correction; ⁇ (/ ⁇ ) represents the corrected k-th subcarrier channel estimation value of the current subframe OFDM symbol; i represents the current subframe; I-1 represents the previous subframe; k is the arrangement position of the subcarriers.
- the step of distinguishing the information of the resource element and calculating the channel coefficient of the resource element according to the information of the resource element includes:
- the channel coefficient of the resource element is linearly interpolated by using the previous resource element of the resource element and the channel coefficient of the subsequent resource element.
- the channel estimation includes the steps of:
- the present invention also provides a channel estimation apparatus in an Orthogonal Frequency Division Multiplexing system, comprising: a packet module, grouping physical resource blocks within a bandwidth of an orthogonal frequency division multiplexing system; Extracting an estimation module, extracting at least one group from the group for channel estimation, and acquiring channel coefficients; wherein, the number of extracted packets is less than the total number of packets;
- the verification module performs MIMO demodulation by using the obtained channel coefficients
- the judging module judges whether the channel estimation for the packet is completed; when the channel estimation is not completed, notifying the decimation estimation module to continue extracting the packet for channel estimation.
- the extraction estimation module includes:
- a first estimating unit estimating a channel coefficient at the reference signal
- the first time domain interpolation unit performs the first time domain interpolation to change the reference signal density on the OFDM symbol including the reference signal to 1/3, and calculates a channel coefficient of the resource element on the OFDM symbol including the reference signal;
- the first frequency domain interpolation unit performs 3 times upper frequency domain interpolation on the OFDM symbol including the reference signal, and obtains a channel coefficient on the OFDM symbol including the reference signal;
- the second time domain interpolating unit performs a second time domain interpolation to calculate channel coefficients of the OFDM symbol without the reference signal by using channel coefficients on the OFDM symbol including the reference signal, thereby obtaining channel coefficients on all OFDM symbols.
- the first time domain interpolation unit includes:
- a first determining subunit determining whether it is a resource element on the first OFDM symbol in the current subframe
- a second determining subunit determining whether the previous subframe of the resource element on the first OFDM symbol in the current subframe is a downlink subframe
- a channel coefficient of the resource element is interpolated by using a previous resource element of the resource element and a channel coefficient line 'I' of the subsequent resource element;
- the second calculation subunit is obtained by linear prediction of channel coefficients of the last two resource elements of the resource element.
- the extraction estimation module includes: a second estimating unit, estimating a channel coefficient at the reference signal;
- a second frequency domain interpolation unit performs 6 times upper frequency domain interpolation on the OFDM symbol including the reference signal to obtain a channel coefficient on the OFDM symbol including the reference signal;
- a third time domain interpolation unit performing first time domain interpolation to correct channel coefficients on the OFDM symbol including the reference signal
- the fourth time domain interpolation unit performs a second time domain interpolation to calculate channel coefficients of the OFDM symbol without the reference signal by using channel coefficients on the OFDM symbol including the reference signal, thereby obtaining channel coefficients on all OFDM symbols.
- the channel estimation method and device in the orthogonal frequency division multiplexing system of the present invention firstly groups physical resource blocks in the bandwidth of the orthogonal frequency division multiplexing system, and then separately performs channel estimation processing for each group of resource blocks to implement Storage sharing saves storage.
- FIG. 1 is a flow chart showing the steps of a channel estimation method in an orthogonal frequency division multiplexing system according to an embodiment of the present invention
- FIG. 2 is a schematic flow chart of steps of a channel estimation method according to another embodiment of the present invention
- FIG. 3 is a schematic flowchart of a process for calculating channel coefficient of a resource element according to an embodiment of the present invention
- FIG. 4 is a schematic diagram of a first time domain interpolation in another embodiment of the present invention.
- FIG. 5 is a schematic flow chart of steps of a channel estimation method according to another embodiment of the present invention.
- FIG. 6 is a schematic diagram of a first time domain interpolation according to another embodiment of the present invention.
- FIG. 7 is a schematic structural diagram of a channel estimation apparatus in an Orthogonal Frequency Division Multiplexing (OFDM) system according to an embodiment of the present invention.
- OFDM Orthogonal Frequency Division Multiplexing
- FIG. 8 is a schematic structural diagram of a decimation estimation module according to another embodiment of the present invention.
- FIG. 9 is a schematic structural diagram of a decimation estimation module according to still another embodiment of the present invention.
- FIG. 10 is a channel estimation apparatus in an orthogonal frequency division multiplexing system according to still another embodiment of the present invention. Set.
- the channel estimation method and apparatus in the orthogonal frequency division multiplexing system of the present invention first divides physical resource blocks (PRBs) within the bandwidth of the orthogonal frequency division multiplexing system into groups, and then separately performs each group of physical resource blocks in sequence. Channel estimation processing to achieve storage sharing, thereby saving storage.
- PRBs physical resource blocks
- an OFDM (Orthogonal Frequency Division Multiplexing) symbol channel estimation result including a reference signal (RS) is optimized to ensure channel estimation performance;
- RS reference signal
- a channel estimation method in an Orthogonal Frequency Division Multiplexing (OFDM) system including:
- Step S10 group physical resource blocks in the bandwidth of the orthogonal frequency division multiplexing system
- Step S11 Extract at least one group from the group for channel estimation, and obtain channel coefficients; wherein, the number of extracted packets is less than the total number of packets;
- Step S12 Perform MIMO demodulation by using the obtained channel coefficients.
- Step S13 Determine whether the channel estimation for the packet is completed, and if yes, end; otherwise, return to step Sl1.
- the physical resource blocks of the M group are sequentially numbered 1 , 2, ..., M.
- channel estimation may be performed on each group of physical resource blocks in sequence to obtain channel coefficients.
- at least one group of calculated channel coefficients may be extracted from the foregoing group; after channel estimation is completed, other physical resource block groups are extracted for channel estimation until The packet channel estimation is all completed.
- the number of packets extracted each time is less than the total number of packets (M).
- the first group of the packets 1 to M may be extracted first for channel estimation, and then the first 1+1 group is extracted, and the channel estimation of the packets 1 to M is completed in this order.
- the channel estimation here does not impose any restrictions on the channel estimation method used.
- MIMO Multi-Input Multiple-Out-put
- step S13 after completing the channel estimation, obtaining the channel coefficients, and demodulating by MIMO, determining whether the channel estimations of all the packets have been completed, and if they have been completed, ending; otherwise, continuing the channel estimation of the packets ( Returning to step S11), steps S11 and S12 are looped until the channel estimation is all completed.
- the channel estimation method in the orthogonal frequency division multiplexing system of this embodiment divides the physical resource blocks in the bandwidth of the orthogonal frequency division multiplexing system into several groups, and then separately performs channel estimation processing on each group of physical resource blocks in order to Achieve storage sharing to save storage.
- the channel estimation in the foregoing step S11 may include:
- Step S110 Estimating a channel coefficient at the reference signal
- Step S11 performing the first time domain interpolation, changing the reference signal density on the OFDM symbol including the reference signal to 1/3, and calculating the channel coefficient of the resource element on the OFDM symbol including the reference signal;
- Step S112 including reference The OFDM symbol of the signal is subjected to 3 times upper frequency domain interpolation to obtain a channel coefficient on the OFDM symbol including the reference signal;
- Step S113 Perform a second time domain interpolation, calculate channel coefficient of the OFDM symbol without the reference signal by using channel coefficients on the OFDM symbol including the reference signal, and obtain channel coefficients on all OFDM symbols.
- step S110 it is first necessary to estimate the channel coefficients at the reference signal (RS).
- step S111 in the first time domain interpolation process, only the channel coefficients on the OFDM symbol containing the reference signal are calculated.
- the channel coefficient calculation of the resource element includes:
- Step S1110 determining whether it is a resource element on the first OFDM symbol in the current subframe; if yes, proceeding to step S1111; otherwise, proceeding to step S1112;
- Step S1 l determining whether the previous subframe of the resource element is a downlink subframe; if yes, proceeding to step S1112; otherwise, proceeding to step S1113;
- Step S1112 linearly interpolating channel coefficients of the resource elements by using channel elements of the previous resource element and the subsequent resource element of the resource element;
- Step S1113 linearly predicting the channel coefficient of the last two resource elements of the resource element.
- the information of the resource elements may be first distinguished, and then the channel coefficients of the resource elements are calculated according to the information of the resource elements.
- the information may include whether it is a resource element on the first OFDM symbol in the current subframe and whether the previous subframe is a downlink subframe or the like.
- the first time domain interpolation requires calculation of the channel coefficients of the resource elements (RE) on the 0#, 4#, 7#, and ll# OFDM symbols, as shown by the hatched portion in FIG. If the previous subframe of the current subframe containing the slash filled portion is a downlink subframe, the time domain interpolation process is as shown by the solid line in FIG. 4, using the arrow start position and the reference at ⁇ 2 , or 2 ) Signal channel coefficient The channel coefficient at the resource element pointed by the linear interpolation arrow.
- RE resource elements
- the 0# OFDM symbol channel coefficient needs to be linearly predicted by using the reference signal channel coefficients at the start positions of the dotted arrows ( 2 and, or 2 and ? 33 ), and the channel coefficients of the remaining resource elements. The calculation is consistent with when the previous subframe is a downlink frame.
- the channel coefficient on the OFDM symbol including the reference signal may be obtained by performing 3 times upper frequency domain interpolation by using the OFDM symbol of the reference signal.
- This kind of sample can be It is implemented by FIR (Constant Impulse Response) filtering, or IFFT (Inverse Fast Fourier Transform) I FFT (Fast Fourier Transform) interpolation.
- step S113 after acquiring the channel coefficients on the OFDM symbol including the reference signal, performing the second time domain interpolation, and calculating the channel of the OFDM symbol without the reference signal by using the channel coefficients on the OFDM symbol including the reference signal. Coefficients to obtain channel coefficients on all OFDM symbols.
- the above time domain or frequency domain interpolation can be performed by referring to the LTE (Long Term Evolution) protocol.
- LTE Long Term Evolution
- the channel estimation method in the orthogonal frequency division multiplexing system of this embodiment optimizes the channel estimation performance by optimizing the OFDM symbol channel estimation result including the reference signal.
- a channel estimation method in an orthogonal frequency division multiplexing system according to still another embodiment of the present invention is proposed.
- the above channel estimation includes:
- Step S120 Estimating a channel coefficient at the reference signal
- Step S121 Perform 6 times uplink frequency domain interpolation on the OFDM symbol including the reference signal, and obtain a channel coefficient on the OFDM symbol including the reference signal.
- Step S122 Perform a first time domain interpolation to correct channel coefficients on the OFDM symbol including the reference signal.
- Step S123 Perform a second time domain interpolation, calculate channel coefficient of the OFDM symbol without the reference signal by using channel coefficients on the OFDM symbol including the reference signal, thereby obtaining all
- the channel coefficients at the reference signal (RS) need to be estimated first.
- the OFDM symbol including the reference signal is first subjected to 6 times upper frequency domain interpolation to obtain channel coefficients on the OFDM symbol including the reference signal. This sample can be used
- step S122 After obtaining the frequency domain interpolation result on the OFDM symbol including the reference signal, as described in step S122, the first time domain interpolation is started, and the OFDM symbol including the reference signals (0#, 4#, 7#, and 11#) is modified. Channel coefficient.
- the current subframe 0# OFDM symbol channel estimation is corrected, if the previous subframe is a downlink subframe, the current subframe is linearly interpolated with the previous subframe 11# OFDM symbol and the current subframe 4# OFDM symbol. 0# OFDM symbol, plus the channel estimate of the current subframe 0# OFDM symbol itself. If the previous subframe is not a downlink subframe, the current subframe 4# OFDM symbol and the current subframe 11# OFDM symbol are linearly interpolated with the current subframe 0# OFDM symbol, and the channel estimation of the current subframe 0# OFDM symbol itself is added. . As the formula:
- N s is the number of OFDM symbols in a single sub-ton
- SymDL represents the current subframe before correction /; # OFDM symbol k-th sub-carrier channel estimation value; represents the corrected current subframe / ⁇ OFDM symbol k-th sub-carrier channel estimation value; The current subframe; i-1 represents the previous subframe; k is the arrangement position of the subcarriers, here the kth subcarrier of the 0# OFDM symbol.
- the current subframe 7# OFDM symbol and the current subframe 0# OFDM symbol may be linearly interpolated with the current subframe 4# OFDM symbol, plus the current subframe 4# OFDM symbol.
- Its own channel estimate, ie k 4.
- the current subframe 7# OFDM symbol and the next subframe 0# OFDM symbol may be linearly interpolated with the current subframe 11# OFDM symbol, plus the current subframe ll#
- the current subframe 11# OFDM symbol and the next subframe 4# OFDM symbol may be linearly interpolated with the next subframe 0# OFDM symbol, plus the next subframe 0.
- the second time domain interpolation is started, and the channel coefficients of the OFDM symbol not including the reference signal may be calculated by using channel coefficients on the OFDM symbol including the reference signal, thereby obtaining Channel coefficients on all OFDM symbols.
- the frequency domain interpolation is reduced by only performing frequency domain interpolation on the OFDM symbol including the reference signal, thereby reducing computational complexity.
- a channel estimation apparatus 20 in an orthogonal frequency division multiplexing system including:
- the grouping module 21 groups the physical resource blocks in the bandwidth of the orthogonal frequency division multiplexing system; the decimation estimation module 22 extracts at least one group from the packets for channel estimation, and obtains channel coefficients; wherein, the number of extracted packets is less than the total Number of groups
- the verification module 23 performs MIMO demodulation by using the channel coefficients acquired by the decimation estimation module 22; the determining module 24 determines whether the channel estimation for the packet is completed; when the channel estimation is not completed, The notification extraction estimation module 22 continues to extract packets for channel estimation.
- the M resource blocks are numbered 1 , 2, ..., M in turn.
- the above-mentioned decimation estimation module 22 may sequentially perform channel estimation on each group of physical resource blocks to obtain channel coefficients.
- at least one set of computation channel coefficients may be extracted from the foregoing packet; after the channel estimation is completed, other physical resource block packets are extracted for channel estimation until the packet channel estimation is completed.
- the number of packets extracted each time is less than the total number of packets (M).
- M the total number of packets
- the first group of the packets 1 to M can be extracted first for channel estimation, and then the 1+1th group is extracted after completion, so that the channel estimation of the packets 1 to M is completed in this order.
- the channel estimation here does not impose any restrictions on the channel estimation method used.
- the above-mentioned checking module 23 can perform MIMO (Multiple-Input Multiple-Output) demodulation by using the channel coefficients acquired by the decimation estimation module 22 after each channel estimation is performed.
- MIMO Multiple-Input Multiple-Output
- the determining module 24 after completing the channel estimation, obtaining the channel coefficients and demodulating by MIMO, determining whether the channel estimations of all the packets have been completed, and if they have been completed, ending; otherwise, continuing the channel estimation of the packet, looping Channel estimation and verification are performed until the channel estimation is all over.
- the channel estimation apparatus 20 in the orthogonal frequency division multiplexing system of the present embodiment divides the physical resource blocks in the bandwidth of the orthogonal frequency division multiplexing system into several groups, and then separately performs channel estimation processing for each group of physical resource blocks. To achieve storage sharing, thereby saving storage.
- the extraction estimation module 22 includes:
- the first time domain interpolation unit 222 performs the first time domain interpolation and uses the OFDM with the reference signal
- the reference signal density on the symbol becomes 1/3, and the channel coefficient of the resource element on the OFDM symbol including the reference signal is calculated;
- the first frequency domain interpolating unit 223 performs 3 times upper frequency domain interpolation on the OFDM symbol including the reference signal to obtain a channel coefficient on the OFDM symbol including the reference signal;
- the second time domain interpolating unit 224 performs a second time domain interpolation to calculate channel coefficients of the OFDM symbols without the reference signal by using channel coefficients on the OFDM symbols including the reference signals, thereby obtaining channel coefficients on all OFDM symbols.
- the first estimating unit 221 needs to estimate the channel coefficient at the reference signal (RS).
- the first time domain interpolation unit 222 calculates the channel coefficients on the OFDM symbol including the reference signal in the first time domain interpolation process.
- the first time domain interpolation unit 222 may include: a first determining subunit 2221, a second determining subunit 2222, a first calculating subunit 2223, and a second calculating subunit 2224; the first determining subunit 2221 Determining whether it is a resource element on the first OFDM symbol in the current subframe; the second determining sub-unit 2222, determining whether the previous subframe of the resource element on the first OFDM symbol in the current subframe is a downlink subframe The first calculating subunit 2223, linearly interpolating the channel coefficients of the resource element by using the previous resource element of the resource element and the channel coefficient of the subsequent resource element; the second calculating subunit 2224, using the resource element The channel coefficients of the last two resource elements are linearly predicted.
- the first determining sub-unit 2221 may first determine whether the calculated resource element is a resource element on the first OFDM symbol in the current subframe; if yes, use the second determining sub-unit 2222 to determine whether the previous subframe of the resource element is a downlink subframe; otherwise, the first resource unit 2223 linearly interpolates the channel coefficients of the resource element by using the previous resource element of the resource element and the channel coefficient of the subsequent resource element; the previous subframe of the resource element is In the downlink subframe, the channel coefficients of the resource element may be linearly interpolated by the first resource unit and the channel coefficient of the latter resource element by the first calculation sub-unit 2223; otherwise, the second calculation sub-unit 2224 is utilized. Above resources The channel coefficients of the last two resource elements of the element are linearly predicted.
- the information of the resource elements may be first distinguished, and then the channel coefficients of the resource elements are calculated according to the information of the resource elements.
- the information may include whether it is the first one in the current subframe
- the resource element on the OFDM symbol and whether the previous subframe is a downlink subframe or the like is a downlink subframe or the like.
- the first time domain interpolation requires calculation of the channel coefficients of the resource elements (RE) on the 0#, 4#, 7#, and ll# OFDM symbols, as shown by the hatched portion in FIG. If the previous subframe of the current subframe including the gray portion is a downlink subframe, the time domain interpolation process is as shown by the solid line in FIG. 4, using the start position of the arrow and the reference signal channel coefficient at or ⁇ and ⁇ ) The channel coefficient at the resource element pointed to by the linear interpolation arrow.
- RE resource elements
- the 0# OFDM symbol channel coefficient needs to be linearly predicted by the reference signal channel coefficients at the start position of the dotted arrow ( 2 and, or 2 and), and the channel coefficients of the remaining resource elements are calculated and
- the previous subframe is the same as the downlink frame.
- the first frequency domain interpolating unit 223 may perform 3 times upper frequency domain interpolation by using an OFDM symbol including a reference signal to obtain a channel coefficient on the OFDM symbol including the reference signal.
- the second time domain interpolating unit 224 performs the second time domain interpolation after acquiring the channel coefficients on the OFDM symbol including the reference signal, and calculates the OFDM without the reference signal by using the channel coefficients on the OFDM symbol including the reference signal. The channel coefficients of the symbols, thereby obtaining channel coefficients on all OFDM symbols.
- the channel estimating apparatus 20 in the orthogonal frequency division multiplexing system of the present embodiment ensures channel estimation performance by optimizing the OFDM symbol channel estimation result including the reference signal.
- the extraction estimation module 22 includes:
- the second frequency domain interpolation unit 232 performs 6 times uplink frequency domain interpolation on the OFDM symbol including the reference signal, and acquires channel coefficients on the OFDM symbol including the reference signal; a third time domain interpolation unit 233, performing first time domain interpolation, and correcting channel coefficients on the OFDM symbol including the reference signal;
- the fourth time domain interpolation unit 234 performs a second time domain interpolation to calculate channel coefficients of the OFDM symbol without the reference signal by using channel coefficients on the OFDM symbol including the reference signal, thereby obtaining channel coefficients on all OFDM symbols.
- the second estimating unit 231 described above needs to estimate the channel coefficient at the reference signal (RS).
- the second frequency domain interpolating unit 232 performs 6 times upper frequency domain interpolation on the OFDM symbol including the reference signal, thereby acquiring channel coefficients on the OFDM symbol including the reference signal.
- the third time domain interpolation unit 233 obtains a frequency domain interpolation result on the OFDM symbol including the reference signal, and starts the first time domain interpolation, and the correction includes the reference signals (0#, 4#, 7#, and 11#). Channel coefficients on OFDM symbols.
- the current subframe 0# OFDM symbol channel estimation is corrected, if the previous subframe is a downlink subframe, the current subframe is linearly interpolated with the previous subframe 11# OFDM symbol and the current subframe 4# OFDM symbol. 0# OFDM symbol, plus the channel estimate of the current subframe 0# OFDM symbol itself. If the previous subframe is not a downlink subframe, the current subframe 4# OFDM symbol and the current subframe 11# OFDM symbol are linearly interpolated with the current subframe 0# OFDM symbol, and the channel estimation of the current subframe 0# OFDM symbol itself is added. . As the formula:
- N s is the number of OFDM symbols in a single sub-ton
- SymDL represents the current subframe before correction /; # OFDM symbol kth subcarrier channel estimation value; ⁇ , represents the corrected current subframe / ⁇ OFDM symbol kth subcarrier channel estimation value; i represents the current subframe; i-1 represents the previous subframe; k is the arrangement position of the subcarriers, here is the 0# OFDM symbol The kth subcarrier.
- the current subframe 7# OFDM symbol and the next subframe 0# OFDM symbol may be linearly interpolated with the current subframe 11# OFDM symbol, plus the current subframe ll#
- the current subframe 11# OFDM symbol and the next subframe 4# OFDM symbol may be linearly interpolated with the next subframe 0# OFDM symbol, plus the next subframe 0.
- the fourth time domain interpolation unit 234 starts the second time domain interpolation after completing the first time domain interpolation, and can calculate the channel coefficient of the OFDM symbol that does not include the reference signal by using the channel coefficient on the OFDM symbol including the reference signal. Thereby obtaining channel coefficients on all OFDM symbols.
- the channel estimation apparatus 20 in the orthogonal frequency division multiplexing system of this embodiment passes only the reference parameters
- the OFDM symbols of the test signal are frequency-domain interpolated to reduce the number of frequency domain interpolations, thereby reducing computational complexity.
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JP2012553169A JP5548785B2 (ja) | 2010-03-24 | 2010-11-02 | 直交周波数分割多重化システムにおけるチャネル推定方法及び装置 |
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JP5548785B2 (ja) | 2014-07-16 |
CN102202029A (zh) | 2011-09-28 |
JP2013520853A (ja) | 2013-06-06 |
US8798178B2 (en) | 2014-08-05 |
IN2012DN06619A (zh) | 2015-10-23 |
EP2515570A1 (en) | 2012-10-24 |
EP2515570A4 (en) | 2015-09-09 |
US20120300884A1 (en) | 2012-11-29 |
CN102202029B (zh) | 2015-01-28 |
EP2515570B1 (en) | 2016-12-21 |
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