CN107809404B - Method and device for estimating symbol offset - Google Patents

Method and device for estimating symbol offset Download PDF

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CN107809404B
CN107809404B CN201610818693.4A CN201610818693A CN107809404B CN 107809404 B CN107809404 B CN 107809404B CN 201610818693 A CN201610818693 A CN 201610818693A CN 107809404 B CN107809404 B CN 107809404B
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path
slave
signal
mth
impulse response
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CN107809404A (en
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王英华
熊高才
李长兴
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ZTE Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2662—Symbol synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0426—Power distribution
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/0848—Joint weighting
    • H04B7/0854—Joint weighting using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking

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Abstract

The invention relates to a method and a device for estimating symbol offset, wherein the method comprises the following steps: calculating the mth slave channel impulse response of the mth slave channel signal, if the power of the mth slave channel first path is smaller than a set threshold value, removing the mth slave channel first path in the mth slave channel impulse response, then respectively taking equal-length paths at the head part and the tail part, calculating the average power of the mth slave channel impulse response and comparing the average power; if the average power of the head path is greater than that of the tail path, the mth slave path signal is shifted to the right relative to the first master path signal; if the average power of the tail path is smaller than the average power of the tail path, the mth slave path signal is offset to the left relative to the first master path signal. The method and the device for estimating the symbol offset can accurately judge the direction and the offset of the symbol offset so as to correspondingly correct and adjust a transmission system.

Description

Method and device for estimating symbol offset
Technical Field
The present invention relates to the field of wireless data transmission technologies, and in particular, to a method and an apparatus for estimating a symbol offset.
Background
With the rapid increase of the demand of wireless data transmission, wireless communication technology has also been rapidly developed. In the prior art, means for improving the transmission capacity and transmission rate of a wireless communication system generally include using polarized antenna transmission, frequency diversity, space diversity, and the like.
The microwave transmission adopting the polarized antenna has the advantages of high speed, high stability, small land resource occupation and the like, and has an important position in actual wireless data transmission. Generally, the microwave transmission usually employs line of Sight (Light of Sight, LoS), and the microwave spatial multiplexing mainly employs a multi-antenna technology, i.e., a Multiple Input Multiple Output (MIMO) technology. The LoS MIMO technology can greatly improve the throughput of the existing broadband system, 2x2LoS MIMO is common at present, and gradually improves towards the direction of 3x3, 4x4 and even NxN LoS MIMO with the continuous updating and development of the technology.
In the LoS MIMO transmission system, due to the fact that the length of the intermediate frequency cable is different among the originating antennas, originating signals are not aligned when the originating signals reach the originating antennas. Therefore, for any receiving antenna, the received signals may also have a misalignment problem. This signal misalignment problem, especially when the signals at the originating end differ by multiple symbols, will cause timing inaccuracy and seriously affect the system performance.
Disclosure of Invention
Therefore, the present invention is directed to a method and apparatus for estimating symbol offset, which can accurately determine the direction and offset of the symbol offset, so as to perform corresponding correction and adjustment on the transmission system.
The invention provides a method for estimating symbol offset, which is used for a transmission system of a multi-input multi-output antenna, and provides a transmitting terminal comprising m transmitting terminal antennas and a receiving terminal comprising m receiving terminal antennas, wherein a signal received by an mth receiving terminal antenna in the receiving terminal from any transmitting terminal antenna in the transmitting terminal is marked as a first main path signal, and a signal received by the mth receiving terminal antenna in the receiving terminal from other transmitting terminal antennas in the transmitting terminal is marked as an mth secondary path signal, and the method comprises the following steps:
calculating the impulse response of the mth slave channel signal;
if the power of the first path of the slave path is smaller than a set threshold value, removing the first path of the slave path in the mth slave path channel impulse response, respectively taking equal-length paths at the head and the tail, respectively recording the equal-length paths as a head path and a tail path, calculating the average power of the head path and the average power of the tail path, and comparing and judging;
if the average power of the head path is greater than the average power of the tail path, shifting the mth slave path signal to the right relative to the first master path signal; if the average power of the head path is smaller than the average power of the tail path, the mth slave path signal is shifted to the left relative to the first master path signal.
The method for estimating the symbol offset, wherein if the power of the slave path first path is less than the set threshold, the method further comprises:
calculating the position weighted average of all paths which are larger than the set threshold except the first path of the slave path in the mth slave path channel impact response, and recording the position weighted average as the slave path position weighted average;
calculating a first main path channel impulse response of the first main path signal; calculating the position weighted average of all paths which are greater than the set threshold except the main path first path in the first main path channel impact response, and recording the position weighted average as a main path position weighted average;
calculating a difference between the weighted average of the slave path positions and the weighted average of the master path positions, wherein if the weighted average of the master path positions is greater than the weighted average of the slave path positions, the mth slave path signal is shifted to the right relative to the first master path signal; if the master path position weighted average is smaller than the slave path position weighted average, the mth slave path signal is shifted to the left relative to the first master path signal.
The method for estimating the symbol offset may further include that, if the power of the slave path first path is greater than the set threshold, the mth slave path signal is not offset with respect to the first master path signal.
The method for estimating the symbol offset, wherein after the step of calculating the mth slave channel impulse response of the mth slave signal, the method further comprises:
windowing is carried out on the head and tail of the mth slave channel impulse response by taking w paths respectively, and the w paths are recorded as a head windowed channel impulse response and a tail windowed channel impulse response respectively;
comparing and judging the power of the w paths in the head windowed channel impulse response and the tail windowed channel impulse response with a first set threshold value;
if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is larger than the first set threshold, reserving the corresponding paths; and if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is smaller than the first set threshold value, setting the corresponding paths to be zero.
The method for estimating the symbol offset, wherein in the step of respectively calculating the mth slave channel impulse responses of the mth slave signal, the method comprises:
obtaining a signal rmlAnd smTo said rmlAnd said smRespectively obtaining r by performing difference operationml' and sm', wherein said rmlA signal with a multiple of symbol rate and a known rate is taken from the head of the main frame for the l frame received by the m receiving end antenna, wherein s ismA local known signal with a multiple symbol rate of the mth path;
using a calculation method of the frequency domain, according to the formula
Figure BDA0001112390430000041
And calculating the impact response of the mth slave channel.
The present invention also provides a device for estimating symbol offset, which is used for microwave transmission of mimo antennas, and provides a transmitting end including m transmitting end antennas and a receiving end including m receiving end antennas, wherein a signal received by an mth receiving end antenna in the receiving end from any transmitting end antenna in the transmitting end is denoted as a first master signal, and a signal received by the mth receiving end antenna in the receiving end from other transmitting end antennas in the transmitting end is denoted as an mth slave signal, the device comprising:
the first calculation module is used for calculating the impact response of the mth slave channel of the mth slave channel signal;
a first determining module, configured to remove the mth slave channel impulse response from the slave channel first path if the power of the slave channel first path is smaller than a set threshold, then take equal-length paths at the head and the tail, respectively, mark the equal-length paths as a head path and a tail path, calculate an average power of the head path and an average power of the tail path, and perform a comparison and determination;
a first determining module, configured to offset the mth slave signal to the right with respect to the first master signal if the average power of the head path is greater than the average power of the tail path; if the average power of the head path is smaller than the average power of the tail path, the mth slave path signal is shifted to the left relative to the first master path signal.
The apparatus for estimating a symbol offset, wherein if the power of the slave first path is less than the set threshold, the apparatus further comprises:
the auxiliary road weighting calculation module is used for calculating the position weighted average of all paths which are larger than the set threshold except the first path of the auxiliary road in the m-th auxiliary road channel impact response and recording the position weighted average as the auxiliary road position weighted average;
the second calculation module is used for calculating a first main path channel impact response of the first main path signal; the main road weighting calculation module is used for solving the position weighted average value of all paths which are larger than the set threshold value except the main road first path in the first main road channel impact response, and recording the position weighted average value as a main road position weighted average value;
a second confirmation module, configured to calculate a difference between the weighted average of the slave path positions and the weighted average of the master path positions, where if the weighted average of the master path positions is greater than the weighted average of the slave path positions, the mth slave path signal is shifted to the right with respect to the first master path signal; if the master path position weighted average is smaller than the slave path position weighted average, the mth slave path signal is shifted to the left relative to the first master path signal.
The apparatus for estimating symbol offset, wherein the first determining module is further configured to confirm that the mth slave signal is not offset with respect to the first master signal if the power of the slave first path is greater than the set threshold.
The apparatus for estimating symbol offset, wherein after the step of calculating the mth slave channel impulse response of the mth slave signal by the first calculating module, the apparatus further comprises a windowing noise reduction module, and the windowing noise reduction module comprises:
a windowing preprocessing unit, configured to take w paths from the head and tail of the mth slave channel impulse response for windowing, and record the w paths as a head windowed channel impulse response and a tail windowed channel impulse response respectively;
a windowing power comparison unit, configured to compare and determine power of the w paths in the head windowing channel impulse response and the tail windowing channel impulse response with a first set threshold;
a windowing post-processing unit, configured to reserve the corresponding path if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is greater than the first set threshold; and if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is smaller than the first set threshold value, setting the corresponding paths to be zero.
The apparatus for estimating a symbol offset, wherein the first calculating module further comprises:
a data differencing unit for obtaining the signal rmlAnd smTo said rmlAnd said smRespectively obtain r by difference operationml' and sm', wherein said rmlFor the m-th frame received by the m-th receiving end antenna, the m-times symbol rate known signal is obtained from the head of the main frame, the smA local known signal with a multiple symbol rate of the mth path;
a channel impulse response calculation unit for calculating a channel impulse response using a frequency domain calculation method according to a formula
Figure BDA0001112390430000061
And calculating the impact response of the mth slave channel.
The method and the device for estimating the symbol offset can accurately judge the direction and the offset of the symbol offset so as to correspondingly correct and adjust a transmission system.
Drawings
Fig. 1 is a schematic block diagram of a method for estimating a symbol offset direction according to a first embodiment of the present invention;
FIG. 2 is a flowchart of estimating a symbol offset direction according to a first embodiment of the present invention;
FIG. 3 is a schematic block diagram of estimating a symbol offset direction and an offset according to a second embodiment of the present invention;
FIG. 4 is a flowchart of estimating a symbol offset direction and an offset according to a second embodiment of the present invention;
FIG. 5 is a flow chart of a method for windowing and denoising according to a third embodiment of the present invention;
fig. 6 is a schematic structural diagram of an apparatus for estimating a symbol offset according to a fourth embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are for convenience of description of the present invention only and do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
Embodiments of the invention and other similar developments will become apparent with reference to the following description and the accompanying drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the embodiments of the invention may be practiced, but it is understood that the scope of the embodiments of the invention is not limited correspondingly. On the contrary, the embodiments of the invention include all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto.
Referring to fig. 1 and fig. 2, fig. 1 is a schematic block diagram of a method for estimating a symbol offset direction according to a first embodiment of the present invention, fig. 2 is a flowchart of a method for estimating a symbol offset direction according to a first embodiment of the present invention, where the method for estimating a symbol offset is used for microwave transmission of a mimo antenna, and provides a transmitting end including m transmitting antennas and a receiving end including m receiving antennas, a signal received by an mth receiving antenna in the receiving end from any one transmitting antenna in the transmitting end is denoted as a first master path signal, and a signal received by the mth receiving antenna in the receiving end from other transmitting antennas in the transmitting end is denoted as an mth slave path signal, where the method for estimating a symbol offset specifically includes:
s101, calculating the impulse response of the mth slave channel of the mth slave channel signal;
s102, if the power of the first path of the slave path is smaller than a set threshold value, removing the first path of the slave path in the mth slave path channel impact response, respectively taking equal-length paths at the head and the tail, respectively recording the equal-length paths as a head path and a tail path, calculating the average power of the head path and the average power of the tail path, and comparing and judging;
s103, if the average power of the head path is greater than the average power of the tail path, shifting the mth slave path signal to the right with respect to the first master path signal; if the average power of the head path is smaller than the average power of the tail path, the mth slave path signal is shifted to the left relative to the first master path signal.
Similarly, as shown in fig. 2, first, the power a of the slave first path is compared with a set threshold B, if the power a of the slave first path is greater than the set threshold B, the mth slave signal is not offset with respect to the first master signal, if the power a of the slave first path is less than the set threshold B, after the mth slave first path in the channel impulse response is removed, winlen paths are taken from the head of the mth slave channel impulse response after the removal of the mth slave first path, the average power C of the paths satisfying the condition is calculated, and winlen paths are taken from the tail, and the average power D of the paths satisfying the condition is calculated. If the average power C of the head part is greater than the average power D of the tail part, the mth slave signal is shifted to the right relative to the first master signal; if the average power C of the head part is smaller than the average power D of the tail part, the mth slave signal is offset to the left relative to the first master signal.
Referring to fig. 3 and 4, fig. 3 is a schematic block diagram of estimating a symbol offset direction and an offset according to a second embodiment of the present invention, and fig. 4 is a flowchart of estimating a symbol offset direction and an offset according to the second embodiment of the present invention, where the method for estimating a symbol offset direction and an offset specifically includes:
s201, obtaining the position weighted average of all paths which are larger than the set threshold value except the first path of the slave path in the mth slave path channel impact response, and recording the position weighted average as the slave path position weighted average;
s202, calculating a first main path channel impact response of the first main path signal;
s203, calculating the position weighted average of all paths which are larger than the set threshold except the main path first path in the first main path channel impact response, and recording as the main path position weighted average;
s204, calculating a difference value between the weighted average value of the slave path positions and the weighted average value of the master path positions, wherein if the weighted average value of the master path positions is greater than the weighted average value of the slave path positions, the mth slave path signal is shifted to the right relative to the first master path signal; if the master path position weighted average is smaller than the slave path position weighted average, the mth slave path signal is shifted to the left relative to the first master path signal.
Similarly, as shown in fig. 4, the power a 'of the slave first path is first compared with a set threshold B', and if the power a 'of the slave first path is greater than the set threshold B', the mth slave signal is not offset with respect to the first master signal; if the power a 'of the slave first path is smaller than the set threshold B', calculating a position weighted average value F of all paths greater than the set threshold B 'except the slave first path in the mth slave channel impulse response, and simultaneously calculating a position weighted average value E of all paths greater than the set threshold B' except the master first path in the first master channel impulse response, and then comparing the magnitude relationship between the master position weighted average value E and the slave position weighted average value F. If the value of the master path position weighted average value E is greater than the slave path position weighted average value F, the mth slave path signal is shifted to the right relative to the first master path signal; if the master path position weighted average E is smaller than the slave path position weighted average F, the mth slave path signal is offset leftward with respect to the first master path signal.
Referring to fig. 5, fig. 5 is a flowchart illustrating a method for windowing and denoising according to a third embodiment of the present invention, which includes the following steps:
s301, windowing w paths at the head and tail of the mth slave channel impulse response, and respectively recording the w paths as a head windowed channel impulse response and a tail windowed channel impulse response;
s302, comparing and judging the power of the w paths in the head windowed channel impulse response and the tail windowed channel impulse response with a first set threshold value;
s303, if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is larger than the first set threshold value, reserving the corresponding paths; and if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is smaller than the first set threshold value, setting the corresponding paths to be zero.
Referring to fig. 6, fig. 6 is a schematic structural diagram of a device for estimating symbol offset according to a fourth embodiment of the present invention, where the device for estimating symbol offset is used for microwave transmission of mimo antennas, and provides a transmitting end including m transmitting-end antennas and a receiving end including m receiving-end antennas, and a signal received by an mth receiving-end antenna in the receiving end from any transmitting-end antenna in the transmitting end is denoted as a first master signal, and a signal received by the mth receiving-end antenna in the receiving end from other transmitting-end antennas in the transmitting end is denoted as an mth slave signal, where the device includes:
and a first calculating module, configured to calculate an mth slave channel impulse response of the mth slave channel signal, where a strongest part of the mth slave channel impulse response is a slave channel first path. The first calculation module comprises a data difference unit and a channel impulse response calculation unit, wherein the data difference unit is used for obtaining a signal rmlAnd smTo said rmlAnd said smRespectively obtain r by difference operationml' and sm', wherein said rmlFor the m-th frame received by the m-th receiving end antenna, the m-times symbol rate known signal is obtained from the head of the main frame, the smIs a multiple of the symbol rate of the mth path. The channel impulse response calculating unit is used for utilizing a calculating method of a frequency domain according to a formula
Figure BDA0001112390430000101
Calculating the m-th slave channel impulse response, wherein
Figure BDA0001112390430000102
And responding to the impact of the mth slave channel.
And a first determining module, configured to, if the power of the first path of the slave path is smaller than a set threshold, remove the first path of the slave path from the mth slave path channel impulse response, then respectively take equal-length paths at the head and the tail, respectively record the equal-length paths as a head path and a tail path, calculate an average power of the head path and an average power of the tail path, and perform a comparison and determination.
A first determining module, configured to offset the mth slave signal to the right with respect to the first master signal if the average power of the head path is greater than the average power of the tail path; if the average power of the head path is smaller than the average power of the tail path, the mth slave path signal is shifted to the left relative to the first master path signal.
The apparatus for estimating a symbol offset further comprises:
the auxiliary road weighting calculation module is used for calculating the position weighted average of all paths which are larger than the set threshold except the first path of the auxiliary road in the m-th auxiliary road channel impact response and recording the position weighted average as the auxiliary road position weighted average;
a second calculating module, configured to calculate a first main path channel impulse response of the first main path signal, where a strongest part of the first main path channel impulse response is a main path first path;
the main road weighting calculation module is used for solving the position weighted average value of all paths which are larger than the set threshold value except the main road first path in the first main road channel impact response, and recording the position weighted average value as a main road position weighted average value;
a second confirmation module, configured to calculate a difference between the weighted average of the slave path positions and the weighted average of the master path positions, where if the weighted average of the master path positions is greater than the weighted average of the slave path positions, the mth slave path signal is shifted to the right with respect to the first master path signal; if the master path position weighted average is smaller than the slave path position weighted average, the mth slave path signal is shifted to the left relative to the first master path signal.
In addition, the apparatus for estimating a symbol offset further comprises a windowing noise reduction module, the windowing noise reduction module comprising:
a windowing preprocessing unit, configured to take w paths from the head and tail of the mth slave channel impulse response for windowing, and record the w paths as a head windowed channel impulse response and a tail windowed channel impulse response respectively;
a windowing power comparison unit, configured to compare and determine power of the w paths in the head windowing channel impulse response and the tail windowing channel impulse response with a first set threshold;
a windowing post-processing unit, configured to reserve the corresponding path if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is greater than the first set threshold; and if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is smaller than the first set threshold value, setting the corresponding paths to be zero.
In the present invention, we take a 2 × 2MIMO multi-antenna microwave transmission system as an example for detailed description, since the 2 × 2MIMO multi-antenna microwave transmission system includes 2 transmitting antennas and 2 receiving antennas, the value of m is 2. In the present invention, let the m times symbol rate known signal received at either end be:
Figure BDA0001112390430000121
h ismlIndicating the channel response, s, corresponding to the l frame signal received by the m receiving endmFor the 2 × 2MIMO multi-antenna microwave transmission system, two paths of signals received by a receiving end are respectively marked as 1H and 2H, and 2 times of symbol rate known signals received by 1H are represented as
Figure BDA0001112390430000122
Wherein h is1lAnd h2lRespectively representing the channel response of 1H and the channel response of 2H, s1And s2Respectively representing a 2 times symbol rate local known signal of 1H and a 2 times symbol rate local known signal of 2H.
For the above 2 × 2MIMO multi-antenna microwave transmission system, the method for estimating the symbol offset mainly includes the following steps:
the method comprises the following steps: obtaining a signal r1lAnd s1R is set by the data differential unit1lAnd s1Respectively perform a difference operation to obtain r1l' and s1'；
Step two: estimating channel impulse response of 2H by the channel impulse response calculation unit
Figure BDA0001112390430000123
Using frequency domain methods according to formula
Figure BDA0001112390430000124
Channel flushing for the 2HEstimating the click response;
step three: channel impulse response to 2H
Figure BDA0001112390430000125
Performing windowing noise reduction processing with noise power of
Figure BDA0001112390430000126
Where P is the local known signal length, W (winlen) is the window length of the noise, pair
Figure BDA0001112390430000127
Carrying out head and tail windowing, respectively taking winlen paths to reduce noise, and ordering:
has a first diameter of
Figure BDA0001112390430000128
A tail diameter of
Figure BDA0001112390430000129
Reserving the first path
Figure BDA00011123904300001210
And the tail diameter
Figure BDA00011123904300001211
The diameter of the first set threshold value Th is larger than that of the first set threshold value Th, and the diameter of the first set threshold value Th is set to be zero;
step four: the invention provides two methods for estimating the symbol offset, the first method is a method for estimating the symbol offset direction only, and specifically comprises the following steps:
first, the situation of signal alignment is eliminated if the power of the first path of the slave path
Figure BDA0001112390430000131
Greater than the set threshold
Figure BDA0001112390430000132
The 2H signal is considered not to be shifted with respect to the 1H signal, where Th1Setting a threshold for the second;
calculating the first path
Figure BDA0001112390430000133
And the tail diameter
Figure BDA0001112390430000134
The average Power of the path reserved in (1) is respectively marked as Power _1 and Power _2, and the magnitude relation of the average Power and the Power _2 is compared;
estimating the symbol offset direction, if power _1 is larger than power _2, then the 2H path signal is shifted to the right relative to the 1H path signal; if power _1 is less than power _2, then the 2H signal is shifted to the left relative to the 1H signal.
The second method can estimate the direction of symbol offset and the magnitude of the offset, specifically:
first, the situation of signal alignment is eliminated if the power of the first path of the slave path
Figure BDA0001112390430000135
Greater than the set threshold
Figure BDA0001112390430000136
The 2H signal is considered not to be shifted with respect to the 1H signal, where Th1Setting a threshold for the second;
secondly, respectively calculating the channel impulse response of 1H
Figure BDA0001112390430000137
Position weighted average of paths retained after noise reduction and 2H channel impulse response
Figure BDA0001112390430000138
The position weighted average of the paths retained after the noise reduction is recorded as
Figure BDA0001112390430000139
And
Figure BDA00011123904300001310
calculating the said
Figure BDA00011123904300001311
And
Figure BDA00011123904300001312
the difference between them, if
Figure BDA00011123904300001313
Is greater than
Figure BDA00011123904300001314
The 2H path signal is shifted to the right relative to the 1H path signal; if it is
Figure BDA00011123904300001315
Is less than
Figure BDA00011123904300001316
The 2H signal is shifted to the left with respect to the 1H signal, and the difference corresponds to the magnitude of the offset.
The method and the device for estimating the symbol offset can accurately judge the direction and the offset of the symbol offset so as to correspondingly correct and adjust a transmission system.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. A method for estimating symbol offset, which is used in a transmission system with mimo antennas, and is characterized in that a transmitting end with m transmitting end antennas and a receiving end with m receiving end antennas are provided, a signal received by an mth receiving end antenna in the receiving end from any transmitting end antenna in the transmitting end is marked as a first master signal, and a signal received by the mth receiving end antenna in the receiving end from other transmitting end antennas in the transmitting end is marked as an mth slave signal, the method comprising:
calculating the m-th slave channel impulse response of the m-th slave channel signal, wherein the strongest part of the m-th slave channel impulse response is a slave channel first path;
if the power of the first path of the slave path is smaller than a set threshold value, removing the first path of the slave path in the mth slave path channel impulse response, respectively taking equal-length paths at the head and the tail, respectively recording the equal-length paths as a head path and a tail path, calculating the average power of the head path and the average power of the tail path, and comparing and judging;
if the average power of the head path is greater than the average power of the tail path, shifting the mth slave path signal to the right relative to the first master path signal; if the average power of the head path is smaller than the average power of the tail path, the mth slave path signal is shifted to the left relative to the first master path signal.
2. The method of claim 1, wherein if the power of the slave first path is less than the predetermined threshold, the method further comprises:
calculating the position weighted average of all paths which are larger than the set threshold except the first path of the slave path in the mth slave path channel impact response, and recording the position weighted average as the slave path position weighted average;
calculating a first main path channel impulse response of the first main path signal; wherein, the strongest part of the first main path channel impact response is a main path first path;
calculating the position weighted average of all paths which are greater than the set threshold except the main path first path in the first main path channel impact response, and recording the position weighted average as a main path position weighted average;
calculating a difference between the weighted average of the slave path positions and the weighted average of the master path positions, wherein if the weighted average of the master path positions is greater than the weighted average of the slave path positions, the mth slave path signal is shifted to the right relative to the first master path signal; if the master path position weighted average is smaller than the slave path position weighted average, the mth slave path signal is shifted to the left relative to the first master path signal.
3. The method according to claim 2, wherein the mth slave signal is not shifted with respect to the first master signal if the power of the slave first path is greater than the set threshold.
4. The method of estimating symbol offset as claimed in claim 3, wherein after the step of calculating the mth slave channel impulse response of the mth slave signal, the method further comprises:
windowing is carried out on the head and tail of the mth slave channel impulse response by taking w paths respectively, and the w paths are recorded as a head windowed channel impulse response and a tail windowed channel impulse response respectively;
comparing and judging the power of the w paths in the head windowed channel impulse response and the tail windowed channel impulse response with a first set threshold value;
if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is larger than the first set threshold, reserving the corresponding paths; and if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is smaller than the first set threshold value, setting the corresponding paths to be zero.
5. The method of estimating symbol offset according to claim 1, wherein in the step of calculating the mth slave channel impulse responses of the mth slave signal, respectively, the method comprises:
obtaining a signal rmlAnd smTo said rmlAnd said smRespectively obtaining r by performing difference operationml' and sm', wherein said rmlFor the m-th frame received by the m-th receiving end antenna, the m-times symbol rate known signal is obtained from the head of the main frame, the smThe local known signal is m times of symbol rate of the mth path;
using a calculation method of the frequency domain, according to the formula
Figure FDA0003125897220000021
And calculating the impact response of the mth slave channel.
6. A device for estimating symbol offset, which is used in a transmission system of mimo antennas, and is characterized in that a transmitting end including m transmitting end antennas and a receiving end including m receiving end antennas are provided, a signal received by an mth receiving end antenna in the receiving end from any transmitting end antenna in the transmitting end is denoted as a first master signal, and a signal received by the mth receiving end antenna in the receiving end from other transmitting end antennas in the transmitting end is denoted as an mth slave signal, the device comprising:
a first calculating module, configured to calculate an mth slave channel impulse response of the mth slave channel signal, where a strongest part of the mth slave channel impulse response is a slave channel first path;
a first determining module, configured to remove the mth slave channel impulse response from the slave channel first path if the power of the slave channel first path is smaller than a set threshold, then take equal-length paths at the head and the tail, respectively, mark the equal-length paths as a head path and a tail path, calculate an average power of the head path and an average power of the tail path, and perform a comparison and determination;
a first determining module, configured to offset the mth slave signal to the right with respect to the first master signal if the average power of the head path is greater than the average power of the tail path; if the average power of the head path is smaller than the average power of the tail path, the mth slave path signal is shifted to the left relative to the first master path signal.
7. The apparatus of claim 6, wherein if the power of the slave first path is less than the predetermined threshold, the apparatus further comprises:
the auxiliary road weighting calculation module is used for calculating the position weighted average of all paths which are larger than the set threshold except the first path of the auxiliary road in the m-th auxiliary road channel impact response and recording the position weighted average as the auxiliary road position weighted average;
the second calculation module is used for calculating a first main path channel impact response of the first main path signal; wherein, the strongest part of the first main path channel impact response is a main path first path;
the main road weighting calculation module is used for solving the position weighted average value of all paths which are larger than the set threshold value except the main road first path in the first main road channel impact response, and recording the position weighted average value as a main road position weighted average value;
a second confirmation module, configured to calculate a difference between the weighted average of the slave path positions and the weighted average of the master path positions, where if the weighted average of the master path positions is greater than the weighted average of the slave path positions, the mth slave path signal is shifted to the right with respect to the first master path signal; if the master path position weighted average is smaller than the slave path position weighted average, the mth slave path signal is shifted to the left relative to the first master path signal.
8. The apparatus according to claim 7, wherein the first determining module is further configured to confirm that the mth slave signal is not shifted with respect to the first master signal if the power of the slave first path is greater than the set threshold.
9. The apparatus of claim 8, wherein after the step of calculating the mth slave channel impulse response of the mth slave signal by the first calculating module, the apparatus further comprises a windowing noise reduction module, the windowing noise reduction module comprising:
a windowing preprocessing unit, configured to take w paths from the head and tail of the mth slave channel impulse response for windowing, and record the w paths as a head windowed channel impulse response and a tail windowed channel impulse response respectively;
a windowing power comparison unit, configured to compare and determine power of the w paths in the head windowing channel impulse response and the tail windowing channel impulse response with a first set threshold;
a windowing post-processing unit, configured to reserve the corresponding path if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is greater than the first set threshold; and if the power of the w paths in the head windowed channel impulse response or the tail windowed channel impulse response is smaller than the first set threshold value, setting the corresponding paths to be zero.
10. The apparatus for estimating symbol offset as claimed in claim 9, wherein said first calculation module further comprises:
a data differencing unit for obtaining the signal rmlAnd smTo said rmlAnd said smRespectively obtain r by difference operationml' and sm', wherein said rmlFor the m-th frame received by the m-th receiving end antenna, the m-times symbol rate known signal is obtained from the head of the main frame, the smThe local known signal is m times of symbol rate of the mth path;
a channel impulse response calculation unit for calculating a channel impulse response using a frequency domain calculation method according to a formula
Figure FDA0003125897220000051
And calculating the impact response of the mth slave channel.
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