CN101398478A - Differential GPS positioning method and system - Google Patents

Abstract

The invention discloses a positioning method and system of differential GPS. The measurement results of M visible GPS satellites together concluded by a plurality of mobile user terminals with the function of A-GPS in the effective area of the differential GPS are used for jointly estimating the position of each user terminal and the differential information. The method includes the following steps: each user terminal receives relevant GPS information from a receiver and independently measures a visible satellite signal; each user terminal submits the measurement result to a server; the server divides the user terminals according to a plurality of effective areas of the differential GPS; aiming at different division areas, the server selects the joint information of N user terminals in the same area to calculate the position and differential information of each terminal; and the server informs the user of the position information of the user terminal.

Description

Differential GPS positioning method and system

Technical field

The present invention relates to the GPS location technology, relate in particular to a kind of differential GPS positioning method and device.

Background technology

GPS is a kind of satellite-based positioning system, and it is designed and be subjected to the control of US military at first by US military, can freely use for anyone.This system is made up of 24 satellites that move on 6 intermediate annular tracks, and satellite rings was around 12 hours around of one week of track operation.Each satellite constantly sends about the position of current time, all satellites and some related data information as almanac (almanac) and ephemeris (ephemeris).Gps receiver uses this information to calculate distance between himself and the satellite.GPS location is that observed quantities such as the pseudorange that utilizes one group of satellite, ephemeris, satellites transmits time realize, also must know user's clock correction simultaneously.Therefore, obtain topocentric three-dimensional coordinate, must measure 4 satellites.

The primary positioning time (TTFF) of GPS location is decided by the receiving sensitivity of receiver to a great extent, and the intensity of the quantity of visible satellite, each satellite-signal, satellite on high distribution and receiver to the visual angle of sky.In a kind of hostile environment, the more weak city high rise building gap of signal or indoor for example needs the time calculating locations of a few minutes under some situation.This is unacceptable for local service (LBS) or urgent call (E911), and these situations need a kind of acquisition time faster.For this reason, people have developed auxiliary type GPS (A-GPS) and have solved TTFF problem under the adverse environment.

Different notions and solution have been developed in the past several years under this keyword of A-GPS, wherein much be subjected to patent protection.These different notions can be divided into support type GPS (Aided GPS) and auxiliary type GPS two classes (Assisted GPS).

Support type GPS improves TTFF by send almanac, ephemeris, rough position and time on the mobile network.This support type data can go up in controlling layer (control plane) and send, perhaps on mobile network's the user level (user plane).The computing great majority of position occur on the mobile device.

Auxiliary type GPS makes and adopts quick TTFF calculating location to become possibility.For realizing this point, utilize the extraneous information as time synchronized, more accurate location, Doppler and frequency to be used for determining the position.This extraneous information can obtain by the infrastructure device of using mobile network's controlling layer, and the mechanism as AFLT (AFLT) is used to determine the position of mobile device.Here, signal sends from mobile device, and several mobile base stations receive and measure.(based on mobile device), perhaps on mobile network's server (based on network) can take place in the calculating of position in mobile device.

Auxiliary type GPS solution based on mobile device receives extra assistant GPS data by the mobile network, but calculates at the enterprising line position of mobile device.LBS or the E911 service that this means must obtain current position from mobile device.

Adopt based on network auxiliary type GPS solution, mobile device sends the GPS secondary server of original gps data in the mobile network.This webserver can utilize and directly come the extra assistant GPS information of automatic network to come calculating location.After calculating, position data is sent to receiver.LBS or E911 service be the location database of access web server directly.

The user level scheme is the A-GPS system that a kind of communication between A-GPS server and mobile device all links based on the all-IP data, it utilizes the IP function of modern wireless network, by IP data network and the mutual supplementary of mobile positioning center (SMLC), the UE of portable terminal (UserEquipment) directly realizes the transmission of locating information from terminal to running fix gateway (GMLC) by the corresponding standard interface.Its corresponding standard is formulated by open mobile alliance (OMA), is called secured user's aspect location (SUPL).The advantage of this mode is to be independent of wireless network deployment, need not the network signal support of each node in wireless access network and the core net, need not radio core network is transformed, and with the 2G Web-compatible, easily realize that cost is low, thereby promote rapidly.

The SUPL locator meams makes the direct end-to-end session of setting up from the terminal to GMLC of portable terminal, realizes the transmission of wireless location information, and by the intercommunication of Le interface realization with the service provider.

As shown in Figure 1, SUPL locating platform 10 (SLP) is made up of the SUPL centre of location 11 (SLC) and SUPL place-centric 12 (SPC) two parts, interface between SUPL locating platform 10 and the SUPL terminal 20 (SET) is LUP (Location User Plane), and interface adopts ULP (the User plane Location Protocol) agreement of OMA.The function that the SET of support SUPL interface function possesses has: privacy functions, security function, SET preparation function, supplementary sending function and position counting function etc.

In SUPL, can be divided into proxy mode and non-proxy mode.

As shown in Figure 2, under proxy mode, SPC 12 no longer directly communicates by letter with SET 20, but finishes communication between SET 20 and the SPC 12 by SLC11 as the agency; In addition, because the difference on terminal attaching ground can be divided into roaming and non-roaming two kinds of situations again.For the ease of discussing, only make analysis here at the communication process of non-roaming proxy mode.Network-side and SET all can initiate network service.

In Fig. 2, signaling process is as follows:

(A) (Home SLP H-SLP) sends a MLP SLIR request message, comprises ms-id, client-id and qop etc. in this message to local locating platform 10 by the SUPL agency;

(B) H-SLP 10 examines current goal SET 20 and is not in the middle of the SUPL roaming and supports the SUPL function;

(C) H-SLP 10 uses WAP Push (WAP PUSH) or short message (SMS) to send a SUPL INIT message to SET, and this message should comprise session-id, posmethod, SLP mode etc.;

(D) after SET 20 receives SUPL INIT, set up the secure data of communicating by letter and be connected with H-SLP 10;

(E) SET 20 begins a location sessions to SUPL POS INIT message of H-SLP 10 transmissions, includes session-id, lid, SET capabilities etc. in this message, and SET may be provided with requested auxiliary data therein;

(F) location protocol that provides according to SUPL POS INIT of H-SLP 10 is chosen corresponding communication agreement (RRLP/RRC/TIA-801) and is carried out continuous locator data exchange with SET 20.

(G) when positional information calculation finishes, H-SLP 10 sends SUPL END message informing SET location sessions to SET 20 to be finished, and the safe IP between SET 20 releases simultaneously and the H-SLP 10 connects and the associated session resource;

(H) H-SLP 10 returns the SET positional information to the SUPL agency by sending MLP SLIA message, discharges all relevant Session Resources simultaneously.

Under non-proxy mode, SPC 12 communicates direct and SET 20.As shown in Figure 3, little by positioning and communicating process and proxy mode difference that SET initiates, identical with Fig. 2 from the step of (E) beginning, after just in the end sending SUPL END message and discharge related resource, whole communication process finishes.Different is that the SUPL agency can be integrated with SET, SET at first sets up with the secure data of H-SLP 10 and is connected, then send SUPL START message to H-SLP, H-SLP sends SUPL RESPONSE message as the response to SUPL START message after examining current goal SET and not being in the middle of the SUPL roaming and supporting the SUPL function.

The benefit of A-GPS is to improve TTFF, increase sensitivity and make the availability maximization, exist these advantages to be because receiver no longer must be downloaded and be decoded from the navigation data of gps satellite, receiver can use more time and processing power to follow the tracks of gps signal.

GPS is a kind of high precision NAVSTAR.At the use initial stage, it can provide high-precision positioning result.At this moment the possessor proposes to utilize differential technique further to improve bearing accuracy to the greatest extent, but because customer requirements is also not urgent, so this technical development is slower.Along with the development of GPS technology and perfect, the further developing of application, people more and more pay attention to utilizing the differential GPS technology to improve positioning performance.Its uses a GPS reference receiver and a receiver user, utilizes in real time or treatment technology afterwards the public error source of cancellation---ionosphere and tropospheric when the user is measured.What propose especially is that when the lift-off of GPS work satellite, U.S. government has carried out the SA policy.Make the orbit parameter of satellite increase very big error, cause some that the high slightly user of positioning accuracy request is not being met.Therefore, develop the differential GPS technology now and just seem more and more important.

In addition, because U.S. government has implemented the SA policy, its result significantly increases satellite clock correction and ephemeris error, makes original real-time positioning precision reduce to 100m from 15m.In this case, utilize differential technique can eliminate this fractional error, more demonstrate the superiority of differential GPS.

In this position fixing process, exist three fractional errors.A part is publicly-owned to each receiver user, for example, and satellite clock error, ephemeris error, ionospheric error, tropospheric error etc.; Second portion is can not be by user's measurement or the propagation delay error that is calculated by calibration model; Third part is the intrinsic error of each receiver user, for example internal noise, channel delay, multipath effect etc.Utilize differential technique, first's error can be eliminated fully, and second portion error major part can be eliminated, and it depends primarily on the distance of reference receiver and receiver user, and the third part error then can't be eliminated.

Pseudo range difference is the widest a kind of technology of present purposes.Nearly all commercial DGPS Receiver all adopts this technology.

The process of pseudo range difference is: a GPS receiver is placed on the accurately known base station in position observes.According to the known precision coordinate of base station, calculate the layback number of base station, and in real time these data are sent by base station to satellite.Receiver user also receives the correction that base station sends, and its positioning result is corrected when carrying out GPS observation, thereby improves bearing accuracy.

Because present pseudo range difference technology depends on accurately known base station of a position, therefore when not existing such base station or equipment can't receive the correction data of base station in effective zone, just can't carry out accurate in locating.

Summary of the invention

Technical matters to be solved by this invention provides a kind of differential GPS positioning method and system, and its portable terminal that can utilize a plurality of A-GPS of possessing functions is united and estimated each user terminal location and difference information the common result who measures of a plurality of gps satellites.

The present invention solves the problems of the technologies described above the technical scheme that adopts to provide a kind of differential GPS positioning method, comprising:

A. each user terminal is measured M satellites in view signal from server reception GPS relevant information and independence;

B. each user terminal reports a server with measurement result;

C. this server is divided user terminal according to a plurality of differential GPSs effective coverage;

D. server is at the zones of different of dividing among the step c, and the united information of selecting to be positioned at N the user terminal of the same area calculates the position and the difference information of each terminal;

E. server is with the customer position information informing user terminal.

In one embodiment, calculating the position of each terminal and the step of difference information in steps d comprises: set up the pseudorange function between user terminal k and the satellite j, it is user terminal location Y _k, one with reference to satellite difference information Δ τ _I0, each other satellites j difference information Δ τ _jFunction, k=0 wherein, 1 ..., (N-1), j=0,1 ..., (M-1); Set up first cost function according to described pseudorange function:

$\min J=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\underset{j=0}{\overset{M-1}{\mathrm{\Σ}}}{f}_{\mathrm{kj}}^2(Y_k,{\mathrm{\Δ\τ}}_{i0},{\mathrm{\Δ\τ}}_j);$

Optimize this first cost function, the united information that obtains user terminal calculates position and each satellite difference information of each terminal.

In another embodiment, calculating the position of each terminal and the step of difference information in the steps d comprises: set up user terminal k with reference to satellite i ₀Between and the pseudorange between user terminal k and the satellite j poor, it is user terminal location Y _k, one with reference to satellite i ₀Difference information Δ τ _I0, each other satellites j difference information Δ τ _jFunction, k=0 wherein, 1 ..., (N-1), j=0,1 ..., (M-1); Define second cost function according to this pseudorange difference:

$\min J=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\underset{j=0,j\≠i0}{\overset{M-1}{\mathrm{\Σ}}}{g}_{\mathrm{ki}0j}^2(Y_k,{\mathrm{\Δ\τ}}_{i0},{\mathrm{\Δ\τ}}_j)$

Optimize this second cost function J, the united information that obtains user terminal calculates position and each satellite difference information of each terminal.

In the step of position of calculating each terminal and difference information, if never carrying out the multi-receiver integrated processes estimates, then optimizing this first or second cost function comes the step of estimating user terminal location and difference information to comprise: relatively report or the measurement result quantity and a fiducial value of the user terminal to send up that writes down, if less than this value, then estimate the position of each user terminal, write down each position Y then according to general GPS method _kIf the measurement result quantity of the user terminal to send up that reports or write down greater than this fiducial value, is then carried out the multi-receiver integrated processes and estimated each user terminal location and difference information, it may further comprise the steps:

Select the location estimation reference position Loc of each user terminal k _Ok, remember that the positional value of the n time estimation is:

${\mathrm{LOC}}_n=\left[\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="Y"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">Y</figure-callout>}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ Y_{N-1}\\ {\mathrm{\&Delta;\&tau;}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ {\mathrm{\&Delta;\&tau;}}_{M-1}\end{array}\right];$

Calculate estimated position LOC the n-1 time _N-1The gradient of the cost function J at place:

$\mathrm{grad}\left(J\right)=\left[\begin{array}{c}\frac{\&PartialD;J}{{\&PartialD;Y}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;Y}_{N-1}}\\ \frac{\&PartialD;J}{\&PartialD;{\mathrm{\&Delta;\&tau;}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{\&PartialD;{\mathrm{\&Delta;\&tau;}}_{M-1}}\end{array}\right];$

Calculate Loc _n=Loc _N-1-μ grad (J), n=1,2..., wherein μ is the step-length of recursive operation;

Judge estimated position Loc the n time _nWith the n-1 time estimated position Loc _N-1Euclidean distance whether less than a regulation estimated accuracy, get back to the step of calculating this gradient grad (J) after then increasing progressively n if not, if Loc then _nBe location estimation for each portable terminal; And

Write down the estimated position of each user terminal and the difference information of each satellite.

Wherein select in the step of location estimation reference position of each user terminal k, if estimate the non-first time, then with the position estimated last time as reference position Loc _OkOtherwise, Loc _OkPosition for general GPS method estimation.

Above-mentioned fiducial value is

M wherein〉4.

In the step of the position of each terminal of aforementioned calculation and difference information, estimate if carried out the multi-receiver integrated processes, then optimize this cost function and come the step of estimating user terminal location and difference information to comprise:

Select user terminal k to be positioned ₀Location estimation reference position Loc _Ok0, remember that the positional value of the n time estimation is:

${\mathrm{LOC}}_n^{\&prime;}=\left[\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="Y\; k"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">Y</figure-callout>}}_k\\ {\mathrm{\&Delta;\&tau;}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ {\mathrm{\&Delta;\&tau;}}_{M-1}\end{array}\right];$

Calculate LOC ' _N-1The cost function J gradient at place:

$\mathrm{grad}(J\&prime;)=\left[\begin{array}{c}\frac{\&PartialD;J}{{\&PartialD;Y}_{\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">k</figure-callout>}0}}\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_{M-1}}\end{array}\right]{|}_{Y_k,k\&NotEqual;\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">k</figure-callout>}0};$

Calculate ${\mathrm{Loc}}_n^{\&prime;}={\mathrm{Loc}}_{n-1}^{\&prime;}-\mathrm{\&mu;}\mathrm{grad}(J\&prime;),$ N=1,2..., wherein μ is the step-length of recursive operation; Judge Loc ' _nWith Loc ' _N-1Euclidean distance whether less than the regulation estimated accuracy, then increase progressively if not and return the step of calculating this gradient grad (J) behind the n and calculate once more, if then final Loc _nBe location estimation for user terminal; And

Recording user terminal k ₀Position and each satellite difference information.

Wherein, select user terminal k to be positioned ₀The step of location estimation reference position in, if estimate the non-first time, then with the position estimated last time as reference position Loc _Ok0Otherwise, Loc _Ok0Position for general GPS method estimation.

In optimizing the step of first or second cost function with the position of estimating each terminal and difference information, also comprise recording user terminal to report measurement result and corresponding on call time; And the measurement result of detection record, if its waiting time is then deleted corresponding record greater than the GPS difference information term of validity.

Above-mentioned differential GPS positioning method also comprises step f, and server issues the corresponding region difference information and gives the user terminal that does not possess reporting ability.

The present invention also provides a kind of Differential GPS Positioning System, utilize N platform in the differential GPS effective coverage to have the mobile subscriber terminal of A-GPS function to M the common result who measures of visual gps satellite, unite and estimate each user terminal location and difference information, this system comprises N user terminal that is positioned at same differential GPS effective coverage at least, location server and the communication network that connects each user terminal and location server, wherein each user terminal is measured described each satellites in view signal from location server reception GPS relevant information and independence, and sends this measurement result; Location server receives this measurement result, according to one by user terminal location Y _k, one with reference to satellite difference information Δ τ _I0, each other satellites j difference information Δ τ _jFirst cost function that is defined $\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{f}_{\mathrm{kj}}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j)$ Perhaps second cost function $\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0,j\&NotEqual;i0}{\overset{M-1}{\mathrm{\&Sigma;}}}{g}_{\mathrm{ki}0j}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j)$ Optimization, carry out the location estimation of user terminal and the estimation of difference information, k=0 wherein, 1 ..., (N-1), j=0,1 ..., (M-1); And transmit this estimated position and difference information and give user terminal.

In the above-mentioned Differential GPS Positioning System, this location server comprises a computing module, in order to carry out to the optimization of this first cost function and this second cost function position and difference information with the estimating user terminal, it comprises: the initial position selected cell, determine the initial value of location estimation, and export this initial value to the location estimation storage unit; The location estimation storage unit is stored the location estimation value of last computation or the location estimation value of initial setting up, and exports the location estimation value of last time to gradient calculation unit, updating block; The gradient calculation unit calculates the Grad of corresponding cost function, to updating block output result of calculation; Updating block is carried out the renewal that user terminal location is estimated, to the location estimation value and the difference information of the current time of decision unit and location estimation storage unit output user terminal; Decision unit judges whether to proceed the location update operations and the location estimation value of storage computation whether, and updating block is given in output storage control; And the measurement result storage unit, storage effectively reports the gps signal measurement result, and the storage data of deletion inefficacy, and the output measurement result is given the gradient calculation unit.

In the above-mentioned Differential GPS Positioning System, if store the corresponding portable terminal location estimation value of last time in the location estimation storage unit, then the initial position selected cell is with the location estimation value of the last time initial value as this location estimation, if there is not the location estimation value of last time in the system, then the position estimated with general GPS method of initial position selected cell is as the initial value of this location estimation.

The present invention is owing to many common results that measure of portable terminal with A-GPS function that utilize in the differential GPS effective coverage, the associating differential parameter, make it compared with prior art, under the situation that does not have the accurate known base station in position, realize the differential GPS technology, improved the bearing accuracy of each portable terminal.

Description of drawings

For above-mentioned purpose of the present invention, feature and advantage can be become apparent, below in conjunction with accompanying drawing the specific embodiment of the present invention is elaborated, wherein:

Fig. 1 is the A-GPS system architecture synoptic diagram of user level mode.

Fig. 2 is the signaling process figure of the proxy mode of user level mode.

Fig. 3 is the signaling process figure of the non-proxy mode of user level mode.

Fig. 4 is a Differential GPS Positioning System structural representation of the present invention.

Fig. 5 is the process flow diagram of an embodiment of differential GPS positioning method of the present invention.

Fig. 6 is the process flow diagram of an embodiment of computed user locations and difference information in the differential GPS positioning method of the present invention.

Fig. 7 is the process flow diagram of another embodiment of computed user locations and difference information in the differential GPS positioning method of the present invention.

Fig. 8 is the process flow diagram of the embodiment of method that among the present invention cost function is optimized.

Fig. 9 is the computing unit structured flowchart in the Differential GPS Positioning System of the present invention.

Embodiment

As shown in Figure 4, Differential GPS Positioning System 100 of the present invention comprises a plurality of user terminals 21, a communication network 22 and a location server 23.Each user terminal 21 possesses the A-GPS function, can and measure according to A-GPS flow process reception gps satellite signal.In the differential GPS effective coverage, the satellites in view 200 of all user terminal 0～N1 is consistent, establishes it for M, is designated as 0,1 respectively ..., (M-1).Each satellite 200 emission gps signal offers each user terminal measurement.

If the location aware of arbitrary satellite i is X in M satellite _i=(x _i, y _i, z _i), j ∈ { 0,1... (M-1) } wherein.And the position of establishing user terminal k to be positioned is Y _k=(x _k, y _k, z _k) the unknown.Then the propagation delay time of user terminal k instrumented satellite i signal is T _Ki, wherein for the disturbance τ of fixed satellite i _iIt in the differential GPS effective coverage unknown fixed value (irrelevant) with user terminal.If satellite i ₀Be the reference satellite, satellite j is for except that with reference to other satellites the satellite, wherein i ₀, j ∈ { 0,1... (M-1) }.If the light velocity is c.

Please shown in Figure 5 in conjunction with Fig. 4 reference, differential GPS positioning method of the present invention may further comprise the steps:

At first, execution in step 201, each user terminal 21 receives the GPS relevant information according to traditional A-GPS flow process and independently the signal of each satellites in view 200 is measured, and wherein measurement result comprises the reference satellite i that user terminal k measures ₀Incoming terminal time (hereinafter referred to as time of arrival) T _Ki0, what user terminal k measured removes with reference to satellite i ₀Outer other satellites j T time of arrival _Kj, then with reference to satellite i ₀With satellite j signal arrival time difference be Δ t _Ki0j=T _Ki0-T _Kj

A traditional A-GPS flow process for example is Fig. 1～user level scheme shown in Figure 3, is not described in detail at this.

Subsequently, in step 202, each user terminal 21 reports location server 23 with measurement result by communication network 22 according to traditional A-GPS flow process.

Execution in step 203, the location server 23 in the network is divided user terminal according to a plurality of differential GPSs effective coverage, and for example user terminal 0～(N-1) is divided in the same area.Wherein, the differential GPS effective coverage generally is that unit divides with the city.

Execution in step 204, location server 23 is at the zones of different of dividing in the step 203, and the united information that utilizes a plurality of (for example N) that select in the step 203 to be positioned at the user terminal 21 of the same area respectively calculates position Y and each satellite difference information Δ τ of each terminal 21 _i, i=0,1 ..., (M-1).Wherein selected user terminal 21 for example is 0～(N-1).

In one embodiment, please refer to Fig. 6, calculate position Y and each satellite difference information Δ τ of each terminal 21 in the step 204 _iMethod as follows:

At first, the ideal of calculating satellite j signal arrival user terminal k does not have the disturbance time (step 301).

The no disturbance time of known ideal is poor between actual time of arrival and the disturbance.If with reference to satellite i ₀The signal ideal that arrives user terminal k not have the disturbance time be T _kThen the satellite j signal ideal that arrives user terminal k does not have the disturbance time and is:

T _kj＝T _k+Δτ _i0-Δτ _j-Δt _kioj ............(1)

Δ τ wherein _I0For being the pseudorange disturbance of satellite 0 (being difference information), Δ τ _jBe the pseudorange disturbance (also being difference information) of satellite j, Δ t _KiojBe reference satellite i ₀Poor with the time of arrival of satellite j.

Secondly, set up the pseudorange (step 302) between user terminal k and the satellite j, it is a unknown parameter: user terminal location, with reference to satellite i ₀The function of disturbance, satellite j disturbance, it meets following relation:

f _kj(Y _k，Δτ _i0，Δτ _j)＝‖Y _k-X _j‖-cT _kj ............(2)

‖ Y wherein _k-X _j‖ is vectorial Y _kWith X _jBetween Euclidean distance.

Moreover, set up first cost function (step 303) according to pseudorange function (2):

$\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{f}_{\mathrm{kj}}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j),............\left(3\right)$

At last, in step 304, optimize the first cost function J, the united information that obtains user terminal calculates position and each satellite difference information Δ τ of each terminal _i, comprise Δ τ _I0With Δ τ _j

In another embodiment, please refer to Fig. 7, calculate position Y and each satellite difference information Δ τ of each terminal 21 in the step 204 _iMethod as follows:

At first, calculate with reference to satellite i ₀The ideal that arrives user terminal k with satellite j signal does not have the disturbance mistiming (step 401).

If with reference to satellite i ₀The signal ideal that arrives user terminal k not have the disturbance time be T _kSatellite i then ₀The ideal that arrives user terminal k with satellite j signal does not have a disturbance mistiming and is:

T _k-T _kj＝ΔT _kioj＝Δt _kioj-Δτ _i0+Δτ _j ............(4)

Δ T wherein _I0Be reference satellite i ₀Disturbance (being difference information), Δ τ _jBe the disturbance of satellite j, Δ t _KiojBe reference satellite i ₀Poor with the time of arrival of satellite j.

Secondly, set up user terminal k with reference to satellite i ₀Between and the pseudorange poor (step 402) between user terminal k and the satellite j, it is a unknown parameter: user terminal location, with reference to satellite i ₀The function of disturbance, satellite j disturbance, it meets following relation:

g _ki0j(Y _k，Δτ _i0，Δτ _j)＝‖Y _k-X _io‖-‖Y _k-X _j‖-cΔT _ki0j ............(5)

Moreover, define second cost function (step 403) according to above-mentioned pseudorange difference function (5):

$\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0,j\&NotEqual;i0}{\overset{M-1}{\mathrm{\&Sigma;}}}{g}_{\mathrm{ki}0j}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j)............\left(6\right)$

At last, in step 404, optimize the second cost function J, the united information that obtains user terminal calculates position and each satellite difference information Δ τ of each terminal _i, comprise Δ τ _I0, Δ τ _j

A kind of embodiment that optimizes above-mentioned first, second cost function is provided below, sees also Fig. 8, its idiographic flow is:

Step 500 judges whether to carry out the multi-receiver integrated processes and estimates.Estimated if never carry out the multi-receiver integrated processes, and then entered step 502, otherwise enter step 520.

In step 502, relatively report or the measurement result quantity and a fiducial value of the user terminal to send up that writes down (for example are

), if then enter step 504, estimate the position of each user terminal to enter step 516 then according to general GPS method less than this value, write down Y _k

If the measurement result quantity of the user terminal to send up that reports or write down greater than

Then enter step 510, carry out the multi-receiver integrated processes and estimate each user terminal location and differential parameter.This multi-receiver integrated processes may further comprise the steps:

At first, select the location estimation reference position Loc of each user terminal k in step 511 _OkWherein, if estimate the non-first time, then with the position estimated last time as reference position Loc _OkOtherwise, Loc _OkPosition for general GPS method estimation.Remember the n time (n=1,2...) positional value of Gu Jiing is:

${\mathrm{LOC}}_n=\left[\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="Y"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">Y</figure-callout>}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ Y_{N-1}\\ {\mathrm{\&Delta;\&tau;}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ {\mathrm{\&Delta;\&tau;}}_{M-1}\end{array}\right]$

Execution in step 512 is calculated LOC _N-1The gradient of the cost function J (with reference to aforementioned formula (3) or (6)) at place is:

$\mathrm{grad}\left(J\right)=\left[\begin{array}{c}\frac{\&PartialD;J}{{\&PartialD;\mathrm{<figure-callout\; id="0"\; label="Y"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">Y</figure-callout>}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;Y}_{N-1}}\\ \frac{\&PartialD;J}{\&PartialD;{\mathrm{\&Delta;\&tau;}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{\&PartialD;{\mathrm{\&Delta;\&tau;}}_{M-1}}\end{array}\right]$

Subsequently, in step 513, calculate Loc _n=Loc _N-1-μ grad (J), n=1,2..., wherein μ is the step-length of recursive operation, depends on performance simulation.

Afterwards, in step 514, if ‖ is Loc _n-Loc _N-1‖＜regulation estimated accuracy (providing) according to application requirements, final Loc _nBe location estimation for each portable terminal; Otherwise return step 512, calculate once more after making n increase by 1, so circulation is up to satisfying above-mentioned stop condition.In one embodiment, above-mentioned steps 512～514 for example is from n=1, carries out recursive calculation.

Step 515 writes down each satellite disturbance Δ τ _i, i=0,1... (M-1) is comprising Δ τ _I0, Δ τ _j

In step 516, record Y _k, k=0,1... (N-1) enters step 506 then.

On the other hand, estimate that then execution in step 520, unite recurrence method estimating user terminal location and differential parameter according to following multi-receiver if system has carried out the multi-receiver integrated processes:

In step 521, select user terminal k to be positioned ₀Location estimation reference position Loc _Ok0Wherein, if estimate the non-first time, then with the position estimated last time as reference position Loc _OkOtherwise, Loc _OkPosition for general GPS method estimation.Remember the n time (n=1,2...) positional value of Gu Jiing is:

${\mathrm{LOC}}_n^{\&prime;}=\left[\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="Y\; k"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">Y</figure-callout>}}_k\\ {\mathrm{\&Delta;\&tau;}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ {\mathrm{\&Delta;\&tau;}}_{M-1}\end{array}\right],$

Wherein, select known other user terminal location Y in the same GPS difference effective coverage owing to carried out the estimation of multi-receiver integrated processes _k(k ≠ k0).

Afterwards, execution in step 522 is calculated LOC ' _N-1J ' the gradient at place:

$\mathrm{grad}(J\&prime;)=\left[\begin{array}{c}\frac{\&PartialD;J}{{\&PartialD;\mathrm{<figure-callout\; id="0"\; label="Y\; k"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">Y</figure-callout>}}_k}\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_{M-1}}\end{array}\right]{|}_{Y_k,k\&NotEqual;\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="A200710046560E00252.png"\; state="\{\{state\}\}">k</figure-callout>}0}$

Afterwards, in step 523, calculate ${\mathrm{Loc}}_n^{\&prime;}={\mathrm{Loc}}_{n-1}^{\&prime;}-\mathrm{\&mu;}\mathrm{grad}(J\&prime;),$ N=1,2..., wherein μ is the step-length of recursive operation, depends on performance simulation.

Step 524 is if ‖ is Loc _n'-Loc _N-1' ‖＜regulation estimated accuracy, final Loc _nBe location estimation for user terminal; Calculate once more otherwise return step 522 after making n increase by 1, up to satisfying above-mentioned stop condition.Wherein estimated accuracy provides according to application requirements.In one embodiment, above-mentioned steps 512～514 for example is from n=1, carries out recursive calculation, therefore makes the location estimation Loc of last acquisition _nSatisfy accuracy requirement.

Step 525, record Δ τ _i, i=0,1... (M-1) is comprising Δ τ _I0, Δ τ _j

Step 526, recording user terminal k ₀Position Y _K0, enter step 506 then.

In step 506, call time on recording user terminal to report measurement result and the correspondence, then execution in step 508, the measurement result of detection record, if its waiting time is then deleted corresponding record greater than the GPS differential parameter term of validity (by the decision of gps system character, being generally 10 minutes).Should be pointed out that step 506 and 508 is not limited to carry out herein, can also before step 510,520, carry out.

Difference information Δ τ at the position Y that has obtained each terminal 21 and each satellite _iAfterwards, execution in step 205, location server 23 is notified each user terminal or other server user's positional informations according to traditional A-GPS flow process.

As an optional embodiment of the present invention, after step 205, also comprise execution in step 206, location server 23 issues the corresponding region difference information according to traditional A-GPS flow process and gives user terminal, and for example other do not have the user terminal N-N1 of reporting ability.

In addition, the invention provides a system that can realize above-mentioned differential GPS positioning method, see also Fig. 4 and shown in Figure 9, Differential GPS Positioning System of the present invention system comprises: have the user terminal 21 of measuring reporting functions, comprise that 0-(N-1) amounts to N; Cordless communication network 22; And location server 23.

Suppose that user terminal 0-(N-1) is positioned at same differential GPS effective coverage, then it has common satellites in view 0-(M-1), and these satellite 200 emission gps signals are to provide each user terminal measurement.

User terminal 0-(N-1) finishes receiving and measures gps satellite signal and report location server 23 by communication network 22.Simultaneously, various auxiliary datas that user terminal 0-(N-1) also can receiving position server 23 and independently positioning.User terminal for example is the mobile phone with A-GPS receiver.

Communication network 22 connects user terminal 21 and location server 23, finishes the data transfer function between user terminal 21 and the location server 23.Communication network 22 for example is a mobile communications network.

Location server 23 carries out data transfer via communication network 22 and each user terminal 21, finish the location estimation of user terminal 0-(N-1) and the assessment function of differential parameter, and carry out the transmission of user terminal 21 desired datas, for example location estimation and differential parameter.

In addition, native system also can comprise not having the user terminal N-N1 that measures reporting functions, and the various auxiliary datas (comprising difference information) that they can receiving position server 23 independently position.

Above-mentioned these parts are configured to carry out above-mentioned step 201～206.The course of work of each parts is described below.

Each user terminal 0-(N-1) receives the GPS relevant information according to traditional A-GPS flow process (as the user level mode) and independently the signal of each satellites in view 0-(M-1) is measured, and wherein establishes the reference satellite i that user terminal k measures ₀Be T time of arrival _Ki0, establish removing that user terminal k measures with reference to satellite i ₀Outer other satellites j time of arrival is T _Kj, and establish with reference to satellite i ₀With satellite j signal arrival time difference be Δ t _Ki0j=T _Ki0-T _Kj

Afterwards, each user terminal 21 reports location server 23 with measurement result by communication network 22 according to traditional A-GPS flow process.

Location server 23 in the communication network 22 is divided user terminal according to a plurality of differential GPSs effective coverage, and wherein user terminal 0～(N-1) is divided in the same area.Location server 23 utilizes N united information that is positioned at the user terminal 0～(N-1) of the same area to calculate the position Y of each terminal 0～(N-1) and the difference information Δ τ of each satellite respectively at the zones of different of dividing in the step 203 _i, i=0,1... (M-1).

At position Y that has obtained each terminal and difference information Δ τ _iAfterwards, location server 23 is notified to each user terminal 0～(N-1) or other servers according to traditional A-GPS flow process with customer position information.In addition, location server 23 also can issue area difference information according to traditional A-GPS flow process and not have the user terminal N-N1 of reporting ability to other.

Location server 23 calculates position Y and each satellite difference information Δ τ of each terminal 21 _iMethod can adopt Fig. 6, mode shown in Figure 7.Wherein, location server 23 comprises a computing module 60, in order to carry out the optimization to first, second represented cost function of calculating formula (3), (6).

As shown in Figure 6, computing module 60 comprises initial position selected cell 601, location estimation storage unit 602, gradient calculation unit 603, updating block 604, decision unit 605 and measurement result storage unit 606.Above-mentioned each parts are configured to carries out calculation process shown in Figure 5.

Wherein, in step 511, initial position selected cell 601 is determined the initial value of location estimation, and to updating block 604 these initial values of output.Wherein if store the corresponding portable terminal location estimation value of last time in the location estimation storage unit 602, then initial position selected cell 601 is with the location estimation value of the last time initial value LOC as this location estimation _Ok, if there is not the location estimation value of last time in the system, then the position estimated with general GPS method (as step 504) of initial position selected cell 601 is as the initial value LOC of this location estimation _Ok

The location estimation value Loc of location estimation storage unit 602 storage last computation _N-1(step 515,516 or step 525,526 result of calculation), perhaps the location estimation value LOC of initial setting up _Ok, and to gradient calculation unit 603, the updating block location estimation value of 604 output last time.

Gradient calculation unit 603 is according to the Grad grad (J) of step 512 or the corresponding cost function J of 522 calculating, to updating block 604 output result of calculations.

Updating block 604 is finished the renewal that user terminal location is estimated according to step 513 or 523, to the location estimation value Y of decision unit 605 and location estimation storage unit 602 output user terminal current times _k(or Y _K0) and difference information Δ τ _i

Decision unit 605 judges whether to proceed the location update operations and the location estimation value of storage computation whether according to step 514 or 524, and updating block 604 is given in output storage control.

606 storages of measurement result storage unit effectively report gps signal measurement result (step 506), as reference satellite i ₀Difference Δ t time of arrival with satellite j _Kioj, and the storage data (step 508) of deletion inefficacy, the output measurement result is given gradient calculation unit 603.

The present invention is owing to many common results that measure of portable terminal with A-GPS function that utilize in the differential GPS effective coverage, the associating differential parameter, make it compared with prior art, under the situation that does not have the accurate known base station in position, realize the differential GPS technology, improved the bearing accuracy of each portable terminal.

Though the present invention discloses as above with preferred embodiment; right its is not in order to qualification the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when can doing a little modification and perfect, so protection scope of the present invention is when with being as the criterion that claims were defined.

Claims (13)

1, differential GPS positioning method, utilize many results in the differential GPS effective coverage with mobile subscriber terminals of A-GPS function to M the common measurement of visual gps satellite, unite and estimate each user terminal location and difference information, it is characterized in that described method comprises:

A. each user terminal is measured the satellites in view signal from server reception GPS relevant information and independence;

B. each user terminal reports a server with measurement result;

C. this server is divided user terminal according to a plurality of differential GPSs effective coverage;

D. server is at the zones of different of dividing among the step c, and the united information of selecting to be positioned at N the user terminal of the same area calculates the position and the difference information of each terminal;

E. server is with the customer position information informing user terminal.

2, differential GPS positioning method as claimed in claim 1 is characterized in that, in the steps d, calculates the position of each terminal and the step of difference information and comprises:

Set up the pseudorange function between user terminal k and the satellite j, it is user terminal location Y _k, one with reference to satellite difference information Δ τ _I0, each other satellites j difference information Δ τ _jFunction, k=0 wherein, 1 ..., (N-1), j=0,1 ..., (M-1);

Set up first cost function according to described pseudorange function:

$\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{f}_{\mathrm{kj}}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j);$

Optimize this first cost function, the united information that obtains user terminal calculates position and each satellite difference information of each terminal.

3, differential GPS positioning method as claimed in claim 1 is characterized in that, in the steps d, calculates the position of each terminal and the step of difference information and comprises:

Set up user terminal k with reference to satellite i ₀Between and the pseudorange between user terminal k and the satellite j poor, it is user terminal location Y _k, one with reference to satellite i ₀Difference information Δ τ _I0, each other satellites j difference information Δ τ _jFunction, k=0 wherein, 1 ..., (N-1), j=0,1 ..., (M-1);

Define second cost function according to this pseudorange difference:

$\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0,j\&NotEqual;i0}{\overset{M-1}{\mathrm{\&Sigma;}}}{g}_{k_i{0}_j}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j)$

Optimize this second cost function J, the united information that obtains user terminal calculates position and each satellite difference information of each terminal.

4, as claim 2 or 3 described differential GPS positioning methods, it is characterized in that, estimated, then optimize this cost function and come the step of estimating user terminal location and difference information to comprise if never carry out the multi-receiver integrated processes:

If the measurement result quantity of the user terminal to send up that relatively reports or write down and a fiducial value less than this value, are then estimated the position of each user terminal according to general GPS method, write down each position Y then _k

If the measurement result quantity of the user terminal to send up that reports or write down greater than this fiducial value, is then carried out the multi-receiver integrated processes and estimated each user terminal location and difference information, it may further comprise the steps:

Select the location estimation reference position Loc of each user terminal k _0k, remember that the positional value of the n time estimation is:

${\mathrm{LOC}}_n=\left[\begin{array}{c}{Y}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ Y_{N-1}\\ {\mathrm{\&Delta;\&tau;}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ {\mathrm{\&Delta;\&tau;}}_{M-1}\end{array}\right];$

Calculate estimated position LOC the n-1 time _N-1The gradient of the cost function J at place:

$\mathrm{grad}\left(J\right)=\left[\begin{array}{c}\frac{\&PartialD;J}{{\&PartialD;Y}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;Y}_{N-1}}\\ \frac{\&PartialD;J}{\&PartialD;\mathrm{\&Delta;}{\mathrm{\&tau;}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_{M-1}}\end{array}\right];$

Calculate Loc _n=Loc _N-1-μ grad (J), n=1,2..., wherein μ is the step-length of recursive operation;

Judge estimated position Loc the n time _nWith the n-1 time estimated position Loc _N-1Euclidean distance whether less than a regulation estimated accuracy, get back to the step of calculating this gradient grad (J) after then increasing progressively n if not, if Loc then _nBe location estimation for each portable terminal;

Write down the estimated position of each user terminal and the difference information of each satellite.

5, differential GPS positioning method as claimed in claim 4 is characterized in that, select in the step of location estimation reference position of each user terminal k, if estimate the non-first time, then with the position estimated last time as reference position Loc _0kOtherwise, Loc _0kPosition for general GPS method estimation.

6, differential GPS positioning method as claimed in claim 4 is characterized in that, this fiducial value is M wherein〉4.

7, as claim 2 or 3 described differential GPS positioning methods, it is characterized in that, estimated, then optimize this cost function and come the step of estimating user terminal location and difference information to comprise if carried out the multi-receiver integrated processes:

Select user terminal k to be positioned ₀Location estimation reference position Loc _0k0, remember that the positional value of the n time estimation is:

${\mathrm{LOC}}_n^{\&prime;}=\left[\begin{array}{c}{Y}_{k0}\\ {\mathrm{\&Delta;\&tau;}}_0\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ {\mathrm{\&Delta;\&tau;}}_{M-1}\end{array}\right];$

Calculate LOC ' _N-1The cost function J gradient at place:

$\mathrm{grad}(J\&prime;)=\left[\begin{array}{c}\frac{\&PartialD;J}{{\&PartialD;Y}_{k0}}\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_0}\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \frac{\&PartialD;J}{{\&PartialD;\mathrm{\&Delta;\&tau;}}_{M-1}}\end{array}\right]{|}_{Y_k,k\&NotEqual;k0};$

Calculate ${\mathrm{Loc}}_n^{\&prime;}={\mathrm{Loc}}_{n-1}^{\&prime;}-\mathrm{\&mu;}\mathrm{grad}(J\&prime;),$ N=1,2..., wherein μ is the step-length of recursive operation;

Judge Loc ' _nWith Loc ' _N-1Euclidean distance whether less than the regulation estimated accuracy, then increase progressively if not and return the step of calculating this gradient grad (J) behind the n and calculate once more, if then final Loc _nBe location estimation for user terminal;

Recording user terminal k ₀Position and each satellite difference information.

8, differential GPS positioning method as claimed in claim 7 is characterized in that, selects user terminal k to be positioned ₀The step of location estimation reference position in, if estimate the non-first time, then with the position estimated last time as reference position Loc _0k0Otherwise, Loc _0k0Position for general GPS method estimation.

9, as claim 4 or 7 described differential GPS positioning methods, it is characterized in that, also comprise:

Call time on recording user terminal to report measurement result and the correspondence; And

The measurement result of detection record is if its waiting time is then deleted corresponding record greater than the GPS difference information term of validity.

10, differential GPS positioning method as claimed in claim 1 is characterized in that, also comprises step f, and server issues the corresponding region difference information and gives the user terminal that does not possess reporting ability.

11, a kind of Differential GPS Positioning System, utilize N platform in the differential GPS effective coverage to have the mobile subscriber terminal of A-GPS function to M the common result who measures of visual gps satellite, unite and estimate each user terminal location and difference information, it is characterized in that, this system comprises that N is positioned at user terminal, the location server of same differential GPS effective coverage and the communication network that connects each user terminal and location server at least, wherein:

Each user terminal is measured described each satellites in view signal from location server reception GPS relevant information and independence, and sends this measurement result;

Location server receives this measurement result, according to one by user terminal location Y _k, one with reference to satellite difference information Δ τ _I0, each other satellites j difference information Δ τ _jFirst cost function that is defined $\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{f}_{\mathrm{kj}}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j)$ Perhaps second cost function $\min J=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{j=0,j\&NotEqual;i0}{\overset{M-1}{\mathrm{\&Sigma;}}}{g}_{k_i{0}_j}^2(Y_k,{\mathrm{\&Delta;\&tau;}}_{i0},{\mathrm{\&Delta;\&tau;}}_j)$ Optimization, carry out the location estimation of user terminal and the estimation of difference information, k=0 wherein, 1 ..., (N-1), j=0,1 ..., (M-1); And transmit this estimated position and difference information and give user terminal.

12, Differential GPS Positioning System as claimed in claim 11, it is characterized in that, this location server comprises a computing module, and in order to carry out the optimization of this first cost function and this second cost function position and the difference information with the estimating user terminal, this computing module comprises:

The initial position selected cell is determined the initial value of location estimation, and exports this initial value to the location estimation storage unit;

The location estimation storage unit is stored the location estimation value of last computation or the location estimation value of initial setting up, and exports the location estimation value of last time to gradient calculation unit, updating block;

The gradient calculation unit calculates the Grad of corresponding cost function, to updating block output result of calculation;

Updating block is carried out the renewal that user terminal location is estimated, to the location estimation value and the difference information of the current time of decision unit and location estimation storage unit output user terminal;

Decision unit judges whether to proceed the location update operations and the location estimation value of storage computation whether, and updating block is given in output storage control;

The measurement result storage unit, storage effectively reports the gps signal measurement result, and the storage data of deletion inefficacy, and the output measurement result is given the gradient calculation unit.

13, Differential GPS Positioning System as claimed in claim 12, it is characterized in that, if store the corresponding portable terminal location estimation value of last time in the location estimation storage unit, then the initial position selected cell is with the location estimation value of the last time initial value as this location estimation, if there is not the location estimation value of last time in the system, then the position estimated with general GPS method of initial position selected cell is as the initial value of this location estimation.

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