Multipath time delay estimation apparatus and method and receiver

Embodiments of the present disclosure provide a multipath time delay estimation apparatus and method and a receiver. Time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. Patent Application which claims priority to Chinese Patent Application No. 201510292559.0, filed Jun. 1, 2015. The disclosure of the priority application is incorporated in its entirety herein by reference.

FIELD

The present disclosure relates to the field of communication technologies, and in particular to a multipath time delay estimation apparatus and method and a receiver.

BACKGROUND

In a wireless communication system, wireless signals are affected by propagation environments, thereby producing reflection, diffraction and scatter in propagation paths. Hence, when signals of a transmitter end arrive at a receiver end, the signals are not transmitted by a single path, but are superimposition of multiple signals transmitted by multiple paths, and this phenomenon is called as a multipath effect. As actual distances of the propagation paths are different, times of arrival of the signals of the paths at the receiver end are different. In an actual communication system, it is often needed to estimate time delay of the multiple paths. Accurate estimation of the time delay of the multiple paths may improve accuracy of measurement of wireless channels, thereby improving channel transmission performance, and furthermore, may also improve positioning precision in positioning applications.

Currently, an existing multipath time delay estimation method often adopts a multiple signal classification (MUSIC) algorithm with super-resolution, including a frequency domain MUSIC algorithm and a time domain MUSIC algorithm.FIG. 1is a flowchart of an existing method for estimating multipath time delay based on the frequency domain MUSIC algorithm. As shown inFIG. 1, the method includes: step101: transmitting signals; step102: receiving signals passing through wireless channels; step103: performing channel estimation in the frequency domain; step104: generating a covariance matrix by using the frequency domain MUSIC algorithm, and performing feature value decomposition and spectral peak search; and step105: performing multipath time delay estimation.

FIG. 2is a flowchart of an existing method for estimating multipath time delay based on the time domain MUSIC algorithm. As shown inFIG. 2, the method includes: step201: transmitting signals; step202: receiving signals passing through wireless channels; step203: performing cross-correlation operations on transmission signals and received signals, so as to obtain cross-correlation values to which different time delays correspond; step204: generating a covariance matrix by using the time domain MUSIC algorithm, and performing feature value decomposition and spectral peak search; and step205: performing multipath time delay estimation.

SUMMARY

In performing the multipath time delay estimation by using the above method based on the frequency domain MUSIC algorithm, a requirement on a signal to noise ratio of the received signals is relatively high, and when there exist paths of relatively strong signal power (hereinafter referred to as “strong paths”) in the multiple paths, a resolution capability to paths of relatively weak signal power (hereinafter referred to as “weak paths”) is lowered, thus time delay of the weak paths cannot be estimated accurately; furthermore, in estimating time delay of multiple paths at the same time, resolution of the time delay estimation is obviously lowered. While in performing the multipath time delay estimation by using the above method based on the time domain MUSIC algorithm, there still exist problems that time delay of the weak paths cannot be estimated accurately due to a lower of a resolution capability to weak paths, time delay, and in estimating time delay of multiple paths at the same time, resolution of the time delay estimation is obviously lowered.

Embodiments of the present disclosure provide a multipath time delay estimation apparatus and method and a receiver. Time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

According to a first aspect of embodiments of the present disclosure, there is provided a multipath time delay estimation apparatus, including: a calculating unit configured to perform cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond; a dividing unit configured to divide time delay of cross-correlation values greater than a first threshold value into at least two subzones; and an estimating unit configured to perform time delay estimation on each signal transmission path in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

According to a second aspect of the embodiments of the present disclosure, there is provided a receiver, including the multipath time delay estimation apparatus described in the first aspect.

According to a third aspect of embodiments of the present disclosure, there is provided a multipath time delay estimation method, including: performing cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond; dividing time delay of cross-correlation values greater than a first threshold value into at least two subzones; and performing time delay estimation on each signal transmission paths in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

An advantage of embodiments of the present disclosure exists in that time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

With reference to the following description and drawings, the particular embodiments of the present disclosure are disclosed in detail, and the principle of the present disclosure and the manners of use are indicated. It should be understood that the scope of embodiments of the present disclosure is not limited thereto. Embodiments of the present disclosure contain many alternations, modifications and equivalents within the scope of the terms of the appended claims.

DETAILED DESCRIPTION

FIG. 3is a schematic diagram of a structure of the multipath time delay estimation apparatus of Embodiment 1 of the present disclosure. As shown inFIG. 3, the apparatus300includes: a calculating unit301, a dividing unit302and an estimating unit303.

The calculating unit301is configured to perform cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond;

the dividing unit302is configured to divide time delay of cross-correlation values greater than a first threshold value into at least two subzones;

and the estimating unit303is configured to perform time delay estimation on each signal transmission path in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

It can be seen from the above embodiment that the time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

In this embodiment, the calculating unit301is configured to perform cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond; for example, the calculating unit301may perform the cross-correlation calculation on a transmission signal and a received signal by using an existing method. A method for performing cross-correlation calculation shall be illustrated below.

At a transmitter end of signals, a transmitter may transmit signals according to Formula (1) below:
Tx(t)=s(t)ejω0t(1);

where, Tx(t) denotes signals transmitted by the transmitter, s(t) is known transmission signals, ω0is a carrier angular frequency, and t is a time.

Wireless channels h(t) passed through by the signals transmitted by the transmitter may be denoted by Formula (2) below:

where, D is the number of multiple paths of the channels, αdis an amplitude of a d-th path, τdis time delay of the d-th path, D and d being positive integers, and t is a time.

At a receiver end of signals, signals received by a receiver after being down converted and ADC (analog-to-digital conversion) sampled may be denoted by Formula (3) below:

where, Rx(n) denotes the signals received by the receiver, D is the number of multiple paths of the channels, w(n) is a noise sequence, λd=αdejω0τdis a complex amplitude of the d-th path of the channels, τdis the time delay of the d-th path, D and d being positive integers, and n is a serial number of sampling points.

The calculating unit301performs the cross-correlation calculation on the transmission signal s(t) and the received signal Rx(n) according to Formula (4) below:

where, Ryx(τ) denotes a cross-correlation value to which time delay τ corresponds, n is a serial number of sampling points, N is the number of the sampling points, n being an integer, N being a positive integer, τ being a non-negative number.

In this embodiment, after the calculating unit301calculates the cross-correlation values to which the different time delays correspond, the dividing unit302divides the time delay of the cross-correlation values greater than the first threshold value into at least two subzones.

In this embodiment, the first threshold value may be set according to an actual situation. For example, the first threshold value may be set to be a product of a maximum value of the cross-correlation values and a predefined ratio, the predefined ratio being, for example, 0.2.

In this embodiment, in the subzones, the time delay may be consecutive. And paths within the same subzone may be made to be within correlation time by dividing the consecutive time delay into the same subzone, thereby further improving accuracy of the time delay estimation.

A method of dividing the time delay of the cross-correlation values greater than the first threshold value into at least two subzones by the dividing unit302shall be exemplarily described below.

FIG. 4is a schematic diagram of cross-correlation function to which different time delays correspond of Embodiment 1 of the present disclosure. As shown inFIG. 4, there exists a corresponding cross-correlation value |Ryx(m)| for each time delay point m, for example, a set of time delay points of the cross-correlation value |Ryx(m)| greater than the first threshold value {m:|Ryx(m)|>The first threshold value}={101,102,103,104,105,107,108,110,111,112,113,115,116,117,118,120,121,122, 124,125, 127,128,129}, m being an integer greater than or equal to 0.

In this embodiment, the dividing unit302may divide the above set into seven zones as below:

In this embodiment, after the dividing unit302divides the time delay into at least two subzones according to the cross-correlation values, the estimating unit303performs time delay estimation on each signal transmission path in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

In this embodiment, in performing time delay estimation on each signal transmission path in each subzone, by setting cross-correlation values of other subzones to be predefined values, influence of strong paths of other subzones on the time delay estimation on each path in the current subzone may be lowered, thereby efficiently improving accuracy of time delay estimation of weak paths. Hence, the predefined values are sufficiently small values, and may be set according to an actual situation. For example, the predefined values are 0.

In this embodiment, in performing time delay estimation on each signal transmission path in each subzone by the estimating unit303, the cross-correlation values of other subzones may be set to be predefined values according to Formula (5) below:

where, Ryx,i,0(m) denotes the cross-correlation values of subzones in performing time delay estimation on an i-th subzone, and m is a time delay point, m and i being integers greater than or equal to 0.

A method of performing time delay estimation on each subzone by the estimating unit303shall be exemplarily described below.

FIG. 5is a flowchart of a method for performing time delay estimation on all subzones by the estimating unit303of Embodiment 1 of the present disclosure. As shown inFIG. 5, the method includes:

Step501: setting cross-correlation values of other subzones than the i-th subzone to be 0;

Step502: performing time delay estimation on paths in the i-th subzone;

Step503: judging whether i is equal to M, M being the number of subzones, 1≦i≦M, and i and M being positive integers; turning to step504when a result of judgment is “no”; and terminating the processing when a result of judgment is “yes”; and

In this embodiment, in respectively performing time delay estimation on each signal transmission path in each subzone by the estimating unit303, the time delay estimation may be performed on all signal transmission paths in the subzone successively starting from a signal transmission path of strongest power in the subzone.

In this embodiment, as there may be one or more current signal transmission paths of strongest power in the subzone, in performing time delay estimation each time, the time delay estimation may be performed on current one or more strongest paths.

Hence, by performing the time delay estimation in the subzones starting from a strong path, influence of strong paths in the subzones on the time delay estimation of the weak paths may be eliminated as possible, thereby further efficiently improving accuracy of time delay estimation.

A structure of the estimating unit303and a method of performing time delay estimation in each subzone of this Embodiment shall be exemplarily described below.

FIG. 6is a schematic diagram of a structure of the estimating unit303of Embodiment 1 of the present disclosure. As shown inFIG. 6, the estimating unit303includes:

a constructing unit601configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, construct a signal subspace and a noise subspace according to a current cross-correlation value of the subzone;

a searching unit602configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, perform spectral peak search according to the signal subspace and the noise subspace, so as to obtain time delay estimation of a current signal transmission path of strongest power of the subzone; and

a determining unit603configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, subtract the current cross-correlation value of the subzone by a cross-correlation value of the current signal transmission paths of strongest power and the transmission signal, and in a case where a result of subtraction is greater than or equal to a second threshold value, determine the result of subtraction as a cross-correlation value used in the next time of performing time delay estimation of the subzone.

FIG. 7is a flowchart of a method for performing time delay estimation in an i-th subzone by the estimating unit303of Embodiment 1 of the present disclosure. As shown inFIG. 7, the method is particular steps of step502inFIG. 5and includes:

Step701: constructing a signal subspace and a noise subspace according to a current cross-correlation value of the subzone;

Step702: performing spectral peak search according to the signal subspace and the noise subspace, so as to obtain time delay estimation of current signal transmission paths of strongest power of the subzone;

Step703: subtracting the current cross-correlation value of the subzone by a cross-correlation value of the current signal transmission paths of strongest power and the transmission signal;

Step704: judging whether a result of subtraction is greater than or equal to a second threshold value, turning to step705when the result of subtraction is “no”, and terminating the time delay estimation of the subzone; and

Step705: determining the result of subtraction as a cross-correlation value used in the next time of performing time delay estimation of the subzone.

In this embodiment, the constructing unit601is configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, construct a signal subspace and a noise subspace according to a current cross-correlation value of the subzone. A structure of the constructing unit of this embodiment and a method of constructing the signal subspace and the noise subspace shall be exemplarily described below.

FIG. 8is a schematic diagram of a structure of the constructing unit601of Embodiment 1 of the present disclosure. As shown inFIG. 8, the constructing unit601includes:

an extracting unit801configured to generate a covariance matrix according to the current cross-correlation value of the subzone, and extract feature values from the covariance matrix;

a first constructing unit802configured to construct the signal subspace according to feature vectors to which feature values greater than a predefined ratio of the maximum feature value in the feature values correspond; and

a second constructing unit803configured to construct the noise subspace according to feature vectors to which feature values less than or equal to the predefined ratio of the maximum feature value in the feature values correspond.

FIG. 9is a flowchart of a method for constructing a signal subspace and a noise subspace by the constructing unit601of Embodiment 1 of the present disclosure. As shown inFIG. 9, the method includes:

Step901: generating a covariance matrix according to the current cross-correlation value of the subzone, and extracting feature values from the covariance matrix;

Step902: constructing the signal subspace according to feature vectors to which feature values greater than a predefined ratio of the maximum feature value in the feature values correspond; and

Step903: constructing the noise subspace according to feature vectors to which feature values less than or equal to the predefined ratio of the maximum feature value in the feature values correspond.

Generating the covariance matrix and extracting the feature values by the extracting unit801, constructing the signal subspace by the first constructing unit802and constructing the noise subspace by the second constructing unit803of this embodiment shall be exemplarily described below.

In this embodiment, s(n−τ) in above Formula (4) may be calculated according to Formula (6) below:

where, N is the number of sampling points, k being an integer, τ is time delay, n is a serial number of sampling points, n being an integer, and N being a positive integer.

Formula (6) is inputted into Formula (4), so as to obtain Formula (7) below:

where, Ryx(τ) is a cross-correlation function, D is the number of multiple paths of a channel, λd=αdejω0τdis a complex amplitude of a d-th path, S(k) is discrete Fourier transform of s(n), and τdis time delay of the d-th path, D and d being positive integers, and k being an integer.

γ(k) is defined according to Formula (8) below:

where, D is the number of multiple paths of the channel, λd=αdejω0τdis the complex amplitude of the d-th path, S(k) is discrete Fourier transform of s(n), τdis the time delay of the d-th path, N is the number of sampling points, N being a positive integer, D and d being positive integers, and k being an integer.

γ(k) may be expressed in a form of a matrix according to Formula (9) below:

D is the number of multiple paths of the channel, λd=αdejω0τdis the complex amplitude of the d-th path, τdis the time delay of the d-th path, N is the number of sampling points, N being a positive integer, and D and d being positive integers.

It can be seen from above formulae (7) and (8) that the cross-correlation function Ryx(τ) is discrete Fourier transform of γ(k). Hence, γ(k) may be obtained by calculating inverse Fourier transform of the cross-correlation function Ryx(τ), that is, Γ=IFFT└Ryx,i,0(m)┘. Therefore, the covariance matrix generated by the extracting unit801may be expressed as E[ΓΓH].

In this embodiment, the extracting unit801may perform feature value decomposition on the covariance matrix E[ΓΓH], so as to obtain the feature values and corresponding feature vectors.

In this embodiment, the first constructing unit802constructs the signal subspace Q according to the feature vectors to which the feature values greater than the predefined ratio of the maximum feature value in the feature values correspond, and the second constructing unit803constructs the noise subspace GAaccording to the feature vectors to which the feature values less than or equal to the predefined ratio of the maximum feature value in the feature values correspond.

In this embodiment, after the constructing unit601constructs the signal subspace Q and the noise subspace GA, an MUSIC time delay spectrum is generated according to Formula (10) below:

The searching unit602performs spectral peak search according to the MUSIC time delay spectrum to obtain time delay estimation τjof the current signal transmission paths of strongest power of the subzone, j denoting a serial number of the current signal transmission paths of strongest power of the subzone.

The determining unit603subtracts the current cross-correlation value of the subzone by the cross-correlation value of the current signal transmission paths of strongest power and the transmission signal, and in the case where the result of subtraction is greater than or equal to the second threshold value, determines the result of subtraction as the cross-correlation value used in the next time of performing time delay estimation of the subzone.

In this embodiment, the determining unit603may perform the subtraction according to Formula (11) below:

where, Ryx,i,1(m) denotes a cross-correlation value used in a next time of performing time delay estimation of an i-th subzone, Ryx,i,0(m) denotes a cross-correlation value used in a current time of performing time delay estimation of the i-th subzone, m is a time delay point,

∑j=1P⁢Ryx⁡(τj′)Rx⁡(0)⁢Rx⁡(m-τj′)
denotes the cross-correlation value of the current signal transmission paths of strongest power and the transmission signal, τ′jdenotes time delay estimation of the current signal transmission paths of strongest power of the i-th subzone, j denotes a serial number of the current signal transmission paths of strongest power of the i-th subzone, and P is the number of the current signal transmission paths of strongest power of the i-th subzone, j and P being positive integers.

In this embodiment Ryx(τ′j) and Rx(m−τ′j) may be obtained by using an existing interpolation method, such as being obtained by using a linear interpolation or spline interpolation method.

In this embodiment, the second threshold value is used to judge whether time delay estimation is performed on all paths in the subzone, and a numeral value of the second threshold value may be set according to an actual situation.

It can be seen from the above embodiment that the time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

An embodiment of the present disclosure further provides a receiver, including a multipath time delay estimation apparatus, a structure and functions of the multipath time delay estimation apparatus being the same as those as described in Embodiment 1, and being not going to be described herein any further.

FIG. 10is a block diagram of a systematic structure of the receiver of Embodiment 2 of the present disclosure. As shown inFIG. 10, the receiver1000may include a central processing unit1001and a memory1002, the memory1002being coupled to the central processing unit1001. This figure is illustrative only, and other types of structures may also be used, so as to supplement or replace this structure and achieve telecommunications function or other functions.

As shown inFIG. 10, the receiver1000may further include a communication module1003, an input unit1004, a display1005, and a power supply1006.

In an implementation, functions of the multipath time delay estimation apparatus may be integrated into the central processing unit1001. In this embodiment, the central processing unit1001may be configured to: perform cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond; divide time delay of cross-correlation values greater than a first threshold value into at least two subzones; and perform time delay estimation on each signal transmission path in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

In this embodiment, in each subzone, the time delay is consecutive.

In this embodiment, the performing time delay estimation on each signal transmission path in each subzone includes: performing time delay estimation on all signal transmission paths in the subzone successively starting from a signal transmission path of strongest power in the subzone.

In this embodiment, each time of performing time delay estimation on the signal transmission paths in the subzone includes: constructing a signal subspace and a noise subspace according to a current cross-correlation value of the subzone; performing spectral peak search according to the signal subspace and the noise subspace, so as to obtain time delay estimation of current signal transmission paths of strongest power of the subzone; and subtracting the current cross-correlation value of the subzone by a cross-correlation value of the current signal transmission paths of strongest power and the transmission signal, and in a case where a result of subtraction is greater than or equal to a second threshold value, determining the result of subtraction as a cross-correlation value used in the next time of performing time delay estimation of the subzone.

In this embodiment, the constructing a signal subspace and a noise subspace according to a current cross-correlation value of the subzone includes: generating a covariance matrix according to the current cross-correlation value of the subzone, and extracting feature values from the covariance matrix; constructing the signal subspace according to feature vectors to which feature values greater than a predefined ratio of the maximum feature value in the feature values correspond; and constructing the noise subspace according to feature vectors to which feature values less than or equal to the predefined ratio of the maximum feature value in the feature values correspond.

In another implementation, the multipath time delay estimation apparatus and the central processing unit1001may be configured separately. For example, the multipath time delay estimation apparatus may be configured as a chip connected to the central processing unit1001, with its functions being realized under control of the central processing unit1001.

In this embodiment, the receiver1000does not necessarily include all the parts shown inFIG. 10.

As shown inFIG. 10, the central processing unit1001is sometimes referred to as a controller or control, and may include a microprocessor or other processor devices and/or logic devices. The central processing unit1001receives input and controls operations of every components of the receiver1000.

The memory1002may be, for example, one or more of a buffer memory, a flash memory, a hard drive, a mobile medium, a volatile memory, a nonvolatile memory, or other suitable devices. And the central processing unit1001may execute the program stored in the memory1002, so as to realize information storage or processing, etc. Functions of other parts are similar to those of the prior art, which shall not be described herein any further. The parts of the receiver1000may be realized by specific hardware, firmware, software, or any combination thereof, without departing from the scope of the present disclosure.

It can be seen from the above embodiment that the time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

An embodiment of the present disclosure further provides a communication system.FIG. 11is a schematic diagram of a structure of the communication system of Embodiment 3 of the present disclosure. As shown inFIG. 11, the communication system1100includes a transmitter1101, a multipath channel1102and a receiver1103. In this embodiment, a structure and functions of the receiver1103are the same as those described in Embodiment 2, and being not going to be described herein any further. And the transmitter1101and the multipath channel1102may have existing structures and functions, and the structures and functions of the transmitter1101and the multipath channel1102are not limited in the embodiments of the present disclosure.

It can be seen from the above embodiment that the time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

An embodiment of the present disclosure further provides a multipath time delay estimation method, corresponding to the multipath time delay estimation apparatus described in Embodiment 1.FIG. 12is a flowchart of the multipath time delay estimation method of Embodiment 4 of the present disclosure. As shown inFIG. 12, the method includes:

Step1201: performing cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond;

Step1202: dividing time delay of cross-correlation values greater than a first threshold value into at least two subzones; and

Step1203: performing time delay estimation on each signal transmission paths in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

In this embodiment, a method for performing cross-correlation calculation on a transmission signal and a received signal, a method for dividing time delay into at least two subzones and a method for performing time delay estimation on each signal transmission paths in each subzone are the same as those described in Embodiment 1, and shall not be described herein any further.

It can be seen from the above embodiment that the time delay is divided into at least two subzones according to cross-correlation values of the transmission signal and the received signal, and time delay estimation is performed on each path in each subzone respectively, thereby efficiently improving resolution of the time delay estimation. And in performing time delay estimation on each path in each subzone, cross-correlation values of other subzones are set to be predefined values, so as to lower influence of strong paths of other subzones on the time delay estimation on each path in the current subzone, thereby efficiently improving accuracy of time delay estimation of weak paths.

An embodiment of the present disclosure further provides a computer-readable program, wherein when the program is executed in a multipath time delay estimation apparatus or a receiver, the program enables the multipath time delay estimation apparatus or the receiver to carry out the multipath time delay estimation method as described in Embodiment 4 time delay.

An embodiment of the present disclosure provides a storage medium in which a computer-readable program is stored, wherein the computer-readable program enables a multipath time delay estimation apparatus or a receiver to carry out the multipath time delay estimation method as described in Embodiment 4 time delay.

The above apparatuses and methods of the present disclosure may be implemented by hardware, or by hardware in combination with software. The present disclosure relates to such a computer-readable program that when the program is executed by a logic device, the logic device is enabled to carry out the apparatus or components as described above, or to carry out the methods or steps as described above. The present disclosure also relates to a storage medium for storing the above program, such as a hard disk, a floppy disk, a CD, a DVD, and a flash memory, etc.

For the implementation of the present disclosure containing the above embodiments, following supplements are further disclosed.

Supplement 1. A multipath time delay estimation apparatus, including:

a calculating unit configured to perform cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond;

a dividing unit configured to divide time delay of cross-correlation values greater than a first threshold value into at least two subzones; and

an estimating unit configured to perform time delay estimation on each signal transmission path in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

Supplement 2. The apparatus according to supplement 1, wherein in each subzone, the time delay is consecutive.

Supplement 3. The apparatus according to supplement 1, wherein in performing time delay estimation on each signal transmission path in each subzone, the estimating unit performs time delay estimation on all signal transmission paths in the subzone successively starting from a signal transmission path of strongest power in the subzone.

Supplement 4. The apparatus according to supplement 3, wherein the estimating unit includes:

a constructing unit configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, construct a signal subspace and a noise subspace according to a current cross-correlation value of the subzone;

a searching unit configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, perform spectral peak search according to the signal subspace and the noise subspace, so as to obtain time delay estimation of current signal transmission paths of strongest power of the subzone; and

a determining unit configured to, in each time of performing time delay estimation on the signal transmission paths in the subzone, subtract the current cross-correlation value of the subzone by a cross-correlation value of the current signal transmission paths of strongest power and the transmission signal, and in a case where a result of subtraction is greater than or equal to a second threshold value, determine the result of subtraction as a cross-correlation value used in the next time of performing time delay estimation of the subzone.

Supplement 5. The apparatus according to supplement 4, wherein the constructing unit includes:

an extracting unit configured to generate a covariance matrix according to the current cross-correlation value of the subzone, and extract feature values from the covariance matrix;

a first constructing unit configured to construct the signal subspace according to feature vectors to which feature values greater than a predefined ratio of the maximum feature value in the feature values correspond; and

a second constructing unit configured to construct the noise subspace according to feature vectors to which feature values less than or equal to the predefined ratio of the maximum feature value in the feature values correspond.

Supplement 6. A receiver, including the apparatus as described in any one of supplements 1-5.

Supplement 7. A communication system, including the receiver as described in supplement 6.

Supplement 8. A multipath time delay estimation method, including:

performing cross-correlation calculation on a transmission signal and a received signal, so as to obtain cross-correlation values to which different time delays correspond;

dividing time delay of cross-correlation values greater than a first threshold value into at least two subzones; and

performing time delay estimation on each signal transmission paths in each subzone respectively; wherein, in performing time delay estimation on each signal transmission path in each subzone, cross-correlation values of other subzones are set to be predefined values.

Supplement 9. The method according to supplement 8, wherein in each subzone, the time delay is consecutive.

Supplement 10. The method according to supplement 8, wherein the performing time delay estimation on each signal transmission paths in each subzone respectively includes:

performing time delay estimation on all signal transmission paths in the subzone successively starting from a signal transmission path of strongest power in the subzone.

Supplement 11. The method according to supplement 10, wherein the performing each time of time delay estimation on the signal transmission paths in the subzone includes:

constructing a signal subspace and a noise subspace according to a current cross-correlation value of the subzone;

performing spectral peak search according to the signal subspace and the noise subspace, so as to obtain time delay estimation of current signal transmission paths of strongest power of the subzone; and

subtracting the current cross-correlation value of the subzone by a cross-correlation value of the current signal transmission paths of strongest power and the transmission signal, and in a case where a result of subtraction is greater than or equal to a second threshold value, determining the result of subtraction as a cross-correlation value used in the next time of performing time delay estimation of the subzone.

Supplement 12. The method according to supplement 11, wherein the constructing a signal subspace and a noise subspace according to a current cross-correlation value of the subzone includes:

generating a covariance matrix according to the current cross-correlation value of the subzone, and extracting feature values from the covariance matrix;

constructing the signal subspace according to feature vectors to which feature values greater than a predefined ratio of the maximum feature value in the feature values correspond; and

constructing the noise subspace according to feature vectors to which feature values less than or equal to the predefined ratio of the maximum feature value in the feature values correspond.