CN1675563A - Method of, and apparatus for, operating a radio system - Google Patents

Abstract

A method of, and an apparatus for, operating a radio system in which a first station (10 or 20) transmits a signal which is received by a second station (20 or 10) at a plurality of spaced locations (24A to 24D). One of the first and second stations transmits and receives a radar signal which is scaled to appear as if it had been transmitted by the other of the first and second stations. The signal received by the second station is analysed by frequency domain analysis to calculate the number of specular reflections and the reflection coefficient for each specular reflection. The scaled signal is analysed to determine bounds for at least one parameter of the specular reflections. The results of the analysis of the radar signal at the second station are utilised to reduce the bounds on the at least one parameter by matching the specular reflection from the frequency domain analysis and the scaled radar signal, and optimising a parameter model of the received signal using the reduced bounds on the at least one parameter and the number of reflections identified in the frequency domain analysis.

Description

The method and apparatus of operate wireless electric system

Technical field

The present invention relates to a kind of method and apparatus of operate wireless electric system.More specifically, the present invention relates to such as in the radio system of communication system through improved Estimation of Parameters, such radio system is cell phone system, the range measurement system that comprises the positioning system that has a plurality of antennas, mimo system, the system that is used for determining having the distance between the station of a plurality of antennas and aforementioned any one system that is implemented in mobile receiver for example.

Background technology

In multi-path environment, institute's emitted radio signal reflects and is received at receiver via the travel path that surpasses from reflecting surface.Two features of multipath signal are that (1) multipath signal always arrives afterwards at direct signal (perhaps sight line (LOS) signal), this is because it must be through long travel path, (2) under normal circumstances multipath signal than direct signal a little less than some, this be because reflection can cause a part of signal power losses.If in some way direct signal is hindered, multipath signal can be stronger.

The various component or the parameter of the signal that receives via different paths have different amplitude (a _n), phase place (θ _n) and postpone (τ _n), this can make that the information that extracts is unreliable from synthetic received signal.For example, if signal conveys data may worsen data error rate so, especially especially like this for high bit rate transmission, and if signal be used for distance estimations, may cause the precision of distance estimations to reduce.If can characterize the multipath attribute of radio signal, so just can reduce harmful effect of multipath transmisstion, for example by offsetting unwanted reflection or reducing this harmful effect by the signal that receives through different paths being synthesized in positive mode.Also there is the system that uses multiple-element antenna (MEA) to realize very high bit-rate transmission.These systems have adopted the sign of the multipath attribute of radio signal." the layering space-time architecture of the radio communication of the decay environment when being used for using multiple-element antenna (Layered Space-Time Architecture for WirelessCommunication in a Fading Environment When Using Multi-Element Antennas) " (author: G.J.Foschini, " warning system technical journal (Bell Systems Technical Journal) ", autumn in 1996,41-59 page or leaf) introduced the MEA system in.

A kind of approach that characterizes multipath transmisstion is to use parameter estimation techniques, (Multipath Estimating Delay-Lock Loop) (MEDLL) (sees such as multipath estimated delay locking ring, for example, " Performance Evaluation of multipath estimated delay locking ring (Performance Evaluation ofthe Multipath Estimating Delay Lock Loop) ", author: B.Townsend, D.J.R.van Nee, P.Fenton and K.Van Dierendonck, Institute of Navigation's whole nation technical conference meeting newspaper (Proceedings of the Institute of Navigation National TechnicalMeeting), the Anaheim, California, 18-20 day January nineteen ninety-five, the 227-283 page or leaf) and minimum mean squares estimator (Minimum-Mean-Square-Estimator) (MMSE) (see, for example, " Conquering Multipath:The GPS Accuracy Battle ", author: L.R.Weill, GPS World, in April, 1997).In parameter estimation techniques, represent received signal by mathematical model, for example such model: the amplitude (a that comprises the component of signal that expression receives via a plurality of travel paths _n), phase place (θ _n) and postpone (τ _n) variable element, and these parameter values are carried out the iteration adjustment, up to the matched well that has obtained between received signal and the mathematical model.

Can also be with reference to " using the multipath channel characteristic (Multipath Channel Characteristics Using Spectral Analysis of theSignal Power Density) of the spectrum analysis of signal power density " (author: S.Zeilinger, T.Talty, MichaelChrysochoos, IEEE Transactions on Broadcasting, the 44th volume, the 4th phase, in Dec, 1998, the the 527th to 539 page), this piece documents the idea that the non-direct signal in the multi-path environment is quantized.The document discloses: by the time dependent power density in the multi-path environment of measuring movable body and the Fourier transform of rated output density then, we can determine the order of reflection under some assumed condition and the reflection coefficient of each reflection.In order to adopt this technology, the path difference between through and non-through must be linear in the whole time period of image data, and Doppler shift radial frequency-time product also must be linear within sampled data is held time.

In general, characterize a large amount of parameter of the Technology Need of multipath transmisstion and therefore efficient is high or precision is lower.

Summary of the invention

An object of the present invention is to improve the method for parameter estimation that uses in any parameter estimation techniques (for example MMSE and MEDLL).

According to a first aspect of the present invention, provided the method that a kind of operation comprises the radio system at first and second stations, this method comprises: first stop transmits, second stands on a plurality of spaced positions and receives the signal of being launched, analyze received signal by frequency-domain analysis, with the number of times of calculating direct reflection and the reflection coefficient of each direct reflection, a station emission in first and second stations is the receiving radar signal also, a described station is adjusted received radar signal, so that it looks like by another emission in first and second stations, to analyzing through the signal of adjusting, thereby determine scope at least one parameter of direct reflection, utilize the analysis result of the radar signal at place, second station, by the direct reflection that will obtain by frequency-domain analysis with mate through the radar signal of adjusting, dwindle the scope of described at least one parameter, and use the scope of described at least one parameter and the order of reflection determined is optimized the parameter model of received signal in frequency-domain analysis through dwindling.

According to a second aspect of the present invention, provided a kind of radio system that comprises first and second stations, first stop has the device that is used to transmit, second station has the device that is used for receiving the signal of being launched on a plurality of spaced positions, be used for analyzing received signal by frequency-domain analysis, device with the reflection coefficient of the number of times that calculates direct reflection and each direct reflection, a station in first and second stations has and is used to launch and the device of receiving radar signal, a described station is adjusted received radar signal, so that it looks like by another emission in first and second stations, thereby second station has and is used for analyzing the device of determining scope at least one parameter of direct reflection through the signal of adjusting, be used to utilize the analysis result of the radar signal at place, second station, by the direct reflection that will obtain by frequency-domain analysis with mate the device of the scope of dwindling described at least one parameter through the radar signal of adjusting and be used for using the scope of described at least one parameter and optimize the device of the parameter model of received signal at the order of reflection that frequency-domain analysis is determined through dwindling.

In according to method of the present invention,, can realize the improved arithmetic accuracy and the efficient that are used for the multipath modeling and slow down by using spectrum analysis in conjunction with back scatter information.By carrying out pre-estimating of parameter, use characterizes multipath such as MEDLL or MMSE and can carry out sooner, therefore and can comprise more parameter obtaining higher precision, thereby the result has obtained correctly separating of the nonlinear problem that caused by MEDLL or MMSE.

Description of drawings

The present invention is introduced by example now with reference to accompanying drawing, wherein:

Accompanying drawing 1 is the schematic block diagram of the radio system in the multi-path environment,

Accompanying drawing 2 be with system shown in the accompanying drawing 1 in the relevant process flow diagram of operation of radio station,

Accompanying drawing 3 is synoptic diagram of geometry of the multipath situation of expression accompanying drawing 1,

Accompanying drawing 4 are distances relevant with the signal that receives to the 24D place of uniformly-spaced antenna 24A in the accompanying drawing 1 with the curve map of the relation curve of power and

Accompanying drawing 5 is curve maps of the relation curve of the frequency at expression non-zero spectrum peak and power.

In the accompanying drawings, identical Reference numeral is used to represent corresponding feature.

Embodiment

For the ease of introducing, will introduce the present invention with reference to MEDLL.

According to MEDLL, the received signal r of the input end of receiver (t) can be write as:

$r\left(t\right)=\underset{n}{\overset{M}{\mathrm{\Σ}}}{a}_n{e}^{j{\mathrm{\θ}}_n}s(t-{\mathrm{\τ}}_n)+n\left(t\right)---\left(1\right)$

A wherein _nBe amplitude,

θ _nBe phase place,

τ _nBe time delay,

S (t) transmits,

N (t) be noise and

M is the sum of direct reflection.

The present invention specifically is applicable to, but is not specially adapted for, and uses better multipath component amplitude (a _n) and the initial estimate of quantity (M) improve the estimated accuracy of all parameters and improve the speed of handling.

In formula (1), a _n, θ _nAnd τ _nThese can be determined by minimum noise item n (t).

Under the situation that receives data D (t), so according to MEDLL, if noise item is the stochastic variable with non-zero Gaussian distribution, then $\underset{t}{\mathrm{\Σ}}n\left(t\right)=0.$

Square error between consequential signal component and the received signal is:

$\underset{t}{\mathrm{\Σ}}{[D\left(t\right)-\underset{n=0}{\overset{M}{\mathrm{\Σ}}}{a}_n{e}^{j{\mathrm{\θ}}_n}s(t-{\mathrm{\τ}}_n)]}^2=\underset{t}{\mathrm{\Σ}}{\left[n\left(t\right)\right]}^2=0---\left(2\right)$

By minimizing this expression formula, we have obtained having not exclusive nonlinear problem of separating.

By obtaining parameter a _n, θ _nAnd τ _nAdvance estimate, can characterize multipath component according to MEDLL or MMSE more apace, and can comprise that so more parameter value realizes higher precision, and more likely draw correctly separating of nonlinear problem.

With reference to the radio system of accompanying drawing 1, comprise that first radio station 10 of first transceiver 12 is connected with first antenna 14 and is connected with first treating apparatus 16.Memory storage 18 is connected with first treating apparatus 16, is used for the temporary transient storage of data.Second station 20 that comprises second transceiver 22 is connected to 24D with a plurality of (for example four) equally spaced second antenna 24A.Second treating apparatus 26 is connected with second transceiver 22, and second memory storage 28 is connected with second treating apparatus 26, is used for the temporary transient storage of data.Transceiver 12,22 all is assembled into and uses spread spectrum signalling to communicate.And first and second reflectings surface 40,50 have been shown in the accompanying drawing 1, these reflectings surface can be for example, to have the wall of identical or different reflection coefficient.In the occasion of practical application, more reflecting surface can be arranged, and here for clear, only shown in Figure 1 two.

In the course of the work, first stop 10 emission omnidirectional signals.Turn back to the backscattering S1 of antenna 12 and S2 is retained and by the first treating apparatus utilization from reflecting surface 40,50, determine first stop with respect to the position of reflecting surface 40,50 (just apart from d _B1/ 2, d _B2/ 2), and first treating apparatus 16 this positional information is included in the omnidirectional signal.If first stop is fixed, so just needn't determine its relative position repeatedly.At 20 places, second station, 24A receives omnidirectional signal to 24D by antenna, and this omnidirectional signal may be the object of multipath or direct reflection.For the ease of explaining, a sight line (LOS) signal 42 and two reflection or multipath signal 44,46 have been provided.

Second treating apparatus 26 adopts suitable technology, such as coming computed range such as the such distance estimations formula of MEDLL.Estimate relevant according to method of the present invention with the improvement of the parameter value of these and other.

Process flow diagram shown in the accompanying drawing 2 has been summarized according to method of the present invention.This method has provided a kind of algorithm that improved multipath is estimated that is used for by the spectrum analysis of adopting the signal power density of carrying out at mobile receiver or multiaerial system at least.This has determined the number of times of direct reflection, has determined the value of each reflection coefficient simultaneously.Radar (or detection) signal that this algorithm uses the power density information on each antenna of multi-aerial receiver and draws from backscattering S1 and S2 is so that improve the efficient or the precision of the parameter estimation of multipath signal.This technology is handled the prompting message of environment, with the auxiliary any system that need know channel.

With reference to accompanying drawing 2, piece 60 relates to: first transceiver, 12 emission omnidirectional signals.Piece 62 relates to: radar (or acoustic detection) information, estimated distance d among first stop 10 receptions and reservation backscattering S1, the S2 _B1And d _B2(accompanying drawing 1) and this range information is included in the follow-up omnidirectional signal to use in the computing of being finished by second treating apparatus 26 in second station 20.Piece 64 relates to: the multipath that comes adjustment face 40,50 to reflect by the processing that will introduce after a while.Piece 66 relates to: second treating apparatus is from through being the amplitude a of the multipath that reflects the backscattering of adjusting _nWith delay τ _nDetermine scope.

Piece 68 relates to: a plurality of antenna 24A receive the distribution of direct line of sight signal and the multipath that reflects and second treating apparatus, 26 rated outputs and distance to 24D.Piece 70 relates to: use Fourier transform for example that the power-range distribution at each antenna place is transformed to spatial frequency domain.Piece 72 relates to: at the distribution of dalta function (perhaps the being called as peak value) check that appears at the nonzero frequency place that causes owing to direct reflection through conversion.Piece 74 relates to: draw the reflection coefficient of direct reflection and draw the sum M (equation 1 and 2) of direct reflection from the sum of dalta function from the power (highly) of dalta function.

Piece 76 relates to: reflection coefficient scope that will draw via backscattering and their delay (piece 66) are complementary with these results that spectrum analysis by the power ratio spatial frequency domain draws.Piece 78 relates to such processing: the amplitude at those and their respective delay scopes are complementary is reduced to accurate more numerical value with amplitude range.The sum of direct reflection or dalta function is known by piece 74, and be can be used for parameter estimation.Piece 80 relates to: draw diffuse background function and in the middle of it being added to computing correct opportunity by the sum of direct reflection.

Piece 82 relates to such selection: use antenna 24A to launch radar (or detection) signal to a selected antenna among the 24D.After this flow process advances to piece 62.

With reference to accompanying drawing 3, it has provided an omnidirectional ranging signal and a radar signal, the omnidirectional ranging signal receives by 20 emissions of second station and by the form of first stop with direct signal and multipath (or direct reflection), and radar signal is by standing 10 emitted transverse to reflecting surface 40,50.The length in through (or LOS) path is d ₀, and the length of two reflection pathss is d ₁(be d _1A+ d _1B) and d ₂(be d _2A+ d _2B).The length of radar (or survey) path S1 and S2 is their half of round trip distance separately, d _B1/ 2 and d _B2/ 2.LOS path d ₀Be respectively with the angle of arrival perpendicular to the straight line of reflecting surface ₁And ₂

By accompanying drawing 3, can draw:

Can summarize these equatioies, thereby apart from d _kCan represent by following equation:

wherein _kBe the angle of arrival of the signal that receives through direct path, and d ₀It is the direct path distance.Angle of arrival _kBe defined as direct path and perpendicular to the angle between the straight line of k reflecting surface, thereby this angle is not intersected by k reflection paths and forms, as shown in Figure 3.

Backscattered model by 16 pairs of received radars of first treating apparatus (or acoustic detection) signal correction function is adjusted on time and amplitude, with approximate when radar (or detection) signal be the reflected signal that when second station 20 emits, should receive.In order to adjust in time, use the signal that this time sampling is contributed advance from the surface of second station 20 through having identical reflection coefficient apart from d _kReplace each d in the equation (3) _KbTo the analysis showed that of the multipath signal geometry shown in the accompanying drawing 3, by the emission of second station 20 and through k reflecting surface the signal of radio station 10 places reception advance apart from d _kCan be expressed as:

For adjusting range, by amplitude a _kReplace each amplitude of samples a _Bk, amplitude a _kBe the situation down-sampling of advancing through surface from second station 20 at signal with identical reflection coefficient the amplitude that should have.Use general being used for of adopting to restrain (inversefourth power law), a with the contrary bipyramid of the range attenuation of advancing _BkCan be expressed as

$a_{b_k}=\frac{B{\mathrm{\μ}}_k}{{d_{b_k}}^2}---\mathrm{for\; k}>0---\left(5\right)$

Wherein B is the amplitude of the back-scattered signal of being launched, and μ _kBe the reflection coefficient of reflecting surface, and a _kCan be expressed as

$a_k=\frac{A{\mathrm{\μ}}_k}{d_k^2}---\mathrm{for\; k}>0---\left(6\right)$

Wherein A is the amplitude that transmits from second station 20.In conjunction with equation (3), (5) and (6), draw

By the d in the expression formula replacement equation (3) of equation (5) _Bk, and by a in the expression formula replacement equation (5) of equation (6) _Bk, having drawn following expression formula, this expression formula is the model through adjusting of received radar (or acoustic detection) related function, promptly represents the expression formula of the model of the signal that receives by 20 emissions of second station and by first stop 10:

R _Bscaled(τ) comprising measured data, be called radar (or acoustic detection) data, is to be drawn by received back-scattered signal and some parameters with unknown-value,

F _b(τ _k) be correlation peak, its peak value is centered close to τ _kRelevant crest and width 2T _c(being the twice of small pieces width).

For the ease of more in depth understanding, will provide the example of a concrete numerical value now according to method of the present invention.Accompanying drawing 4 is the power (ordinate) of the back-scattered signal that received to 24D (accompanying drawing 1) by antenna 24A and the curve map of distance (horizontal ordinate).The Fourier transform of the curve of power shown in the accompanying drawing 5 expression accompanying drawings 4 and distance is in order to obtain power density spectrum and the graphic extension non-zero frequency spectrum wave crest in the k space.

D (t) is the signal data that receives.

$\underset{t}{\mathrm{\Σ}}D\left(t\right)s(t-\mathrm{\τ})=K\left(t\right)$ It is the related function that receives.

Obtain the initial estimation of parameter:

$K\left(\mathrm{\τ}\right)=F_b\mathrm{scaled}\left(\mathrm{\τ}\right)+a_0{e}^{j{\mathrm{\θ}}_0}{F}_b\left({\mathrm{\τ}}_0\right)$

Wherein K (τ) is a ranging data.

Solve d by this equation ₀And _k, a ₀And θ ₀

By d ₀And _kWe have obtained a by top equation (7) and (4) _kAnd d _k

So from the back-scattered signal through adjusting, we have obtained a for all components ₀, θ ₀, d ₀, _k, a _kAnd d _kInitial estimate.

Investigate the spectrum peak shown in the accompanying drawing 5, can obtain amplitude a ₁..., a _nValue.These amplitudes are mated, and in the process of eliminating multipath according to the signal that receives, use the accurate more range value that obtains by analysis of spectrum,, can carry out distance estimations by this line of sight signal to obtain sight line (LOS) signal.

Having a plurality of equally spaced antennas though the embodiment shown in the accompanying drawing 1 shows second station 20, is not spacing to equate for them.For second station 20, another feasible scheme is to have an antenna and with the motion of constant speed, thereby carries out spatial sampling to received signal with the time increment that equates.And for the signal of being propagated by station 10, there is no need is omnidirectional.

With reference to international patent application IB 02/02734 (applicant's case PHGB 010139) and IB 02/02735 (applicant's case PHGB 010140), wherein IB 02/02734 relates to by main reflective information and measures accurate distance and arrive angle, IB 02/02735 relates to by the backscattering DATA REASONING accurate distance through adjusting and arrives angle, and the detailed content of these two patented claims is incorporated the application by reference into.

In the application's instructions and claims, the speech " " or " one " that appear at an element front do not get rid of the situation that has a plurality of this kind elements.In addition, speech " comprises " not getting rid of also have other the element or the situation of step except listed.

By reading disclosure of the present invention, for a person skilled in the art, other modification will be conspicuous.These modifications can be included in design, manufacturing and the application of radio distance-measuring system well-known features and corresponding ingredient and can be used for replacing the disclosed feature of this paper or operable feature except feature disclosed herein.

Industrial applicibility

The present invention relates to the improved ginseng in the radio system such such as communication system, used Number estimates, such wireless system for example cell phone system, comprise deciding with a plurality of antennas The range-measurement system, mimo system of position system and be used for determining with the distance between the station of a plurality of antennas From system.

Claims (10)

1. an operation comprises first and second stations (10, the method of radio system 20), this method comprises: first stop (10 or 20) transmits, second station (20 or 10) receives the signal of being launched on a plurality of spaced positions, analyze received signal by frequency-domain analysis, with the number of times of calculating direct reflection and the reflection coefficient of each direct reflection, a station emission in first and second stations is the receiving radar signal also, a described station is adjusted received radar signal, so that it looks like by another emission in first and second stations, to analyzing through the signal of adjusting, thereby determine scope at least one parameter of direct reflection, utilize the analysis result of the radar signal at place, second station, by the direct reflection that will obtain by frequency-domain analysis with mate through the radar signal of adjusting, dwindle the scope of described at least one parameter, and use the scope of described at least one parameter and the order of reflection determined is optimized the parameter model of received signal in frequency-domain analysis through dwindling.

2. in accordance with the method for claim 1, it is characterized in that described at least one parameter is amplitude (a _n).

3. in accordance with the method for claim 1, it is characterized in that described at least one parameter is time delay (τ _n).

4. in accordance with the method for claim 1, it is characterized in that, determine the scope of at least two parameters.

5. in accordance with the method for claim 4, it is characterized in that described at least two parameters are amplitude (a _n) and time delay (τ _n).

6. in accordance with the method for claim 1, it is characterized in that second station comprises the antenna that separates on a plurality of spaces that are used to receive the signal of being launched.

7. in accordance with the method for claim 1, it is characterized in that received signal (r (t)) is to use following equation to estimate

$r\left(t\right)=\underset{n}{\overset{M}{\mathrm{\Σ}}}{a}_n{e}^{j{\mathrm{\θ}}_n}s(t-{\mathrm{\τ}}_n)+n\left(t\right)$

A wherein _nBe amplitude,

θ _nBe phase place,

τ _nBe time delay,

S (t) transmits,

N (t) be noise and

M is the sum of direct reflection.

8. in accordance with the method for claim 1, it is characterized in that, frequency-domain analysis is undertaken by following manner: obtain the power at (68) acceptance point place and the distribution of distance, with the distribution transformation (70) of power and distance is power and spatial frequency domain spectrum, note (72) because the non-zero spectrum peak in power that direct reflection causes and the spatial frequency domain spectrum, and the reflection coefficient that the scope of at least one parameter of multipath reflection and spectrum conformal analysis by power and spatial frequency domain are drawn mates (76,78) to draw the value more accurately of described at least one parameter.

9. one kind comprises first and second stations (10,20) radio system, this first stop (10 or 20) has the device (12 that is used to transmit, 14), second station (20 or 10) has the device (22 that is used for receiving the signal of being launched on a plurality of spaced positions, 24A is to 24D), be used for analyzing received signal with the number of times of calculating direct reflection and the device (26) of the reflection coefficient of each direct reflection by frequency-domain analysis, a station in first and second stations has and is used to launch and the device (12 of receiving radar signal, 14), a described station is adjusted received radar signal, so that it looks like by another emission in first and second stations, second station has and is used for thinking that through the signal analysis of adjusting at least one parameter of direct reflection determines the device (26) of scope, be used to utilize the analysis result of the radar signal at place, second station, dwindle described at least one parameter (a by the direct reflection that will obtain by frequency-domain analysis with mating through the radar signal of adjusting _n, τ _n) the device and being used for of scope use the scope of described at least one parameter and optimize the device of the parameter model of received signal at the order of reflection that frequency-domain analysis is determined through dwindling.

10. according to the described radio system of claim 9, it is characterized in that second station comprises separated antenna (24A is to 24D) on a plurality of spaces that are used to receive the signal of being launched.

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