CN103197327A

CN103197327A - Method and system for updating global position system (GPS) ephemeris fast and reliably

Info

Publication number: CN103197327A
Application number: CN2013101295960A
Authority: CN
Inventors: 黄琦; 潘策荣; 杜锐; 周洪杰
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2013-04-12
Filing date: 2013-04-12
Publication date: 2013-07-10
Anticipated expiration: 2033-04-12
Also published as: CN103197327B

Abstract

The invention relates to a method and system for quickly and reliably updating GPS ephemeris. The system sets up a local GPS ephemeris server. The local GPS ephemeris server has a built-in virtual GPS ephemeris generation module. Under normal circumstances, the local GPS ephemeris server obtains ephemeris data from the official GPS ephemeris server. When the local GPS ephemeris server is disconnected from the GPS official ephemeris server, the virtual GPS ephemeris generation module starts to work to generate accurate virtual ephemeris, and the GPS ephemeris data of the local GPS ephemeris server will immediately switch to the internal virtual ephemeris GPS ephemeris data to ensure the continuity and reliability of GPS ephemeris data. It can help each A-GPS terminal host to significantly shorten the TTFF time (time to first fix after power-on). Therefore, the time for the first positioning after the cold start of the A-GPS terminal positioning system can be shortened to within 20 seconds, realizing fast and reliable positioning.

Description

A kind of fast and reliable is upgraded the method and system of GPS ephemeris

Technical field

The present invention relates to a kind of fast and reliable and upgrade the method and system of GPS ephemeris.

Background technology

When the application of GPS constantly advanced individual's carry-on application, no small use bottleneck had just appearred in traditional GPS locator meams.Adopt the free-standing GPS equipment of autonomous location (Autonomous Positioning), must in the good open skies of signal conditioning, receive the satellite-signal more than four, and, the GPS receiver of this equipment must collect these gps satellite orbit information data integrities, then just can position calculating.

Startup positioning time after the GPS receiver is started shooting for the first time, depend on the mode of startup, generally can be divided into three kinds of cold start-up, startup temperature and warm starts:

Cold start-up (Cold Start): the GPS receiver has emptied all historical datas, perhaps GPS receiver displacement under the situation that does not power up work surpasses 1000km, the GPS receiver can be attempted location and locking satellite, owing to emptied historical data, will need long time.The GPS receiver adopts the method that is similar to poll, locking signal from all satellites, and this will be than knowing that in advance which satellite of needs search is a lot of slowly.This class is obtained locking again and is wanted the time spent very long.According to using GPS module difference, obtain time of locking again and hour do not wait from a few minutes to one.

Position, almanac and UTC time that warm startup (Warm Start): GPS preserves the satellite of last calculating, but the content of preserving is not the data of current satellites in view.Can attempt obtaining current satellite and signal after GPS is restarted and calculate its reposition.GPS can roughly infer current day aerial satellites in view based on its last position and almanac.

Warm start (Hot Start): GPS preserves position, almanac (almanac) and the UTC time of its last satellites in view of calculating, and after restarting, GPS is the latest position that the basis obtained and calculated current satellite with the content of above-mentioned preservation, can locate fast.

For carry-on navigation application, because the existence of cold start-up, independently be positioned at (the Time to first fix positioning time first time after the start, TTFF) oversize, and the user is in the street that buildings stands in great numbers, under the overpass often, or even in the indoor environment, because these local signal condition of acceptances are very poor, the user needs could wait until for a long time location for the first time, but also not necessarily can be successful.

In the case for single A-GPS end host, startup location mode the most fast is exactly warm start, and obtain the auxiliary positioning mode of satellite information by another set of network, cold start-up is become warm start, just A-GPS(is Aiding GPS), become the developmental inexorable trend of GPS.At this situation, two kinds of multi-form A-GPS solutions are arranged in the market, shorten the TTFF time to help the user, realize the location fast.

A kind of is online A-GPS mode (AssistNow Online), and the mobile communication system such as GSM, GPRS, CDMA or UMTS of passing through of real-time obtain real-time satellite information.Another kind is to adopt off-line A-GPS mode (AssistNow offline), by the mobile network or directly download satellite data in advance by the Internet, just can play the effect of auxiliary positioning when needed.A-GPS involved in the present invention is online A-GPS.

The portable terminal of traditional online A-GPS mode generally communicates by letter with traditional standard ephemeris server (also can be mirror image (Mirror) or agency's (Proxy) ephemeris server of server) by the protocol mode of TCP/IP, to obtain the required secondary satellite locator data in GPS location.Almanac data on the tradition ephemeris server is generally from GPS official ephemeris server, and just said GPS root ephemeris server obtains.And the term of validity of almanac data only is several hours, when traditional ephemeris server and GPS root ephemeris server disconnect be connected after, each A-GPS end host main frame just can't obtain up-to-date GPS ephemeris, can't locate fast.

Summary of the invention

The present invention is directed to the deficiencies in the prior art, proposed the solution that a kind of fast and reliable is upgraded the A-GPS ephemeris.Even help each A-GPS end host can't directly obtain under the situation of up-to-date GPS ephemeris from GPS root ephemeris server at local GPS ephemeris server, also can obtain up-to-date high precision virtual GPS ephemeris at local GPS ephemeris server, to help the user to shorten the TTFF time, realize the location fast.Thereby can be with the time of location shortened in 20 seconds for the first time after the cold start-up of A-GPS end host positioning system.

The technical scheme that technical solution problem of the present invention is taked is:

The system that a kind of fast and reliable is upgraded the GPS ephemeris comprises a plurality of A-GPS end hosts and a local GPS ephemeris server.Described local GPS ephemeris server, inside comprises a virtual GPS ephemeris generation module.Described virtual GPS ephemeris generation module is a GPS ephemeris prediction module of moving on the local GPS ephemeris server.This prediction module is used historical GPS almanac data, in conjunction with the operation characteristic of satellite, infers the next satellite transit track of several hrs by the algorithm of difference ephemeris correction data, generates comparatively accurate satellite almanac data.

Each A-GPS end host is by the connected mode of GPRS or WIFI, and the local GPS ephemeris server on the visit internet obtains up-to-date GPS almanac data.

Utilizing said system to upgrade the method consists two processes of GPS ephemeris, is respectively that the A-GPS end host obtains the GPS ephemeris from local GPS ephemeris server; Local GPS ephemeris server obtains ephemeris from GPS root ephemeris server.

The A-GPS end host obtains GPS ephemeris process from local GPS ephemeris server, and step comprises:

The 101:A-GPS end host powers on, and system's each several part is carried out initialization.

102: judge whether to upgrade the satellite ephemeris in the GPS module, if do not need to upgrade with regard to execution in step 107, upgrade if desired, with regard to execution in step 103.

103: judge whether terminal GSM/GPRS or WIFI have inserted the internet.If be connected to the internet with regard to execution in step 104, if be not connected to the internet with regard to execution in step 107.

104: terminal can be connected to local GPS ephemeris server after inserting the internet, determines the correct back execution in step 105 that connects.

105: download up-to-date GPS almanac data to the A-GPS end host from local GPS ephemeris server, execution in step 106 after finishing.

After the 106:A-GPS end host has obtained up-to-date GPS ephemeris, convert almanac data to unified GPS module discernible inner ephemeris format, re-use the ephemeris update command of GPS module, almanac data is updated to the A-GPS end host.Execution in step 107 after finishing.

107: system can wait for A-GPS end host location, finishes up to the location, and A-GPS end host ephemeris renewal process finishes.

(2) local GPS ephemeris server obtains the process of ephemeris from GPS root ephemeris server, and step comprises:

201: the every interval of local GPS ephemeris server connected a GPS root ephemeris server in 2 seconds, when timing reaches 2 seconds, and execution in step 202.

202: local GPS ephemeris server can at first attempt connecting first GPS root ephemeris server of first-selection in the tabulation, if can not connect, and execution in step 203.If can connect, execution in step 206.

203: attempt connecting second standby GPS root ephemeris server, if can not connect, if can connect with regard to execution in step 204., execution in step 206.

204: attempt connecting the 3rd standby GPS root ephemeris server, if can not connect, if execution in step 205. can connect execution in step 206.

205: attempt connecting n standby GPS root ephemeris server, if can not connect, system will jump out the connection task, execution in step 206, if can connect, also execution in step 206.

206: local GPS ephemeris server can judge whether and can carry out communication with above-mentioned a plurality of GPS root ephemeris servers, if can normal communication, and execution in step 208, if can not communication, reporting system obtains the connection failure of GPS root ephemeris server.Execution in step 207.

207: system can start the virtual GPS ephemeris module, by the GPS almanac data that obtains before, according to the algorithm of difference ephemeris correction data, obtains accurate GPS ephemeris, and execution in step 210 after finishing.

208: after local GPS ephemeris server and (3,4,5,7) GPS root ephemeris server connected, whether GPS root ephemeris server can be inquired about by system the GPS almanac data that can upgrade.When system detects new almanac data generation, execution in step 209, if do not detect new data updated, Data Update finishes, and waits for next data updating process, execution in step 201.

209: enable almanac data and download, download to local GPS ephemeris server with new almanac data is complete.

210: after local GPS ephemeris server obtains new GPS almanac data from GPS root ephemeris server or virtual GPS ephemeris generation module, data can be changed, convert the ephemeris array that the GPS module can be identified to, be saved in the local GPS ephemeris server, wait for that the A-GPS end host reads, execution in step 201 is carried out next one circulation.

The A-GPS end host is updated to the A-GPS end host to the GPS almanac data by using GPS ephemeris update command, converts the cold start-up process of system to warm start.

The present invention can assist each A-GPS end host, lose with GPS root ephemeris server at local GPS ephemeris server and to be connected, can't obtain under the situation of up-to-date GPS ephemeris from GPS root ephemeris server, same can the realization located fast, helps each A-GPS end host to shorten TTFF time (positioning time first time after the start).

Description of drawings

Fig. 1. GPS almanac data update system theory diagram;

Fig. 2. from local GPS ephemeris server update A-GPS end host ephemeris process;

Fig. 3. local GPS ephemeris server obtains GPS root ephemeris server ephemeris process.

Embodiment

Below in conjunction with accompanying drawing the specific embodiment of the present invention is described

Fig. 1 is GPS almanac data update system theory diagram.An actual A-GPS end host 6 and the local GPS ephemeris server 2 of comprising of GPS ephemeris update system.The A-GPS end host can have a lot of, and local GPS ephemeris server has only one.Local GPS ephemeris server inside comprises a virtual GPS ephemeris generation module 1.Local GPS ephemeris server has been connected to the internet, obtains up-to-date almanac data from each GPS

root ephemeris server

3,4,5,7.When local GPS ephemeris server and each GPS root ephemeris server disconnect when being connected, the almanac data source of inside can switch on the internal virtual GPS ephemeris generation module immediately.Virtual GPS ephemeris generation module can be under local GPS ephemeris server and situation that the of short duration disconnection of GPS root ephemeris server is connected, according to the satellite ephemeris that obtains before, algorithm by difference ephemeris correction data (Differential Almanac Correction Data), extrapolate next several hrs, even tens hours comparatively accurate satellite almanac data, thereby generate a high-precision virtual GPS ephemeris.The virtual satellite almanac data of this part can break away from the isolated operation of GPS root ephemeris server, and the term of validity can reach 5 days under the limiting case.

What thereby the assurance system can be reliable and stable provides GPS almanac data.Each A-GPS end host is selected the mode of GPRS or WIFI to be connected to local GPS ephemeris server automatically according to current network connection situation and is downloaded up-to-date ephemeris.Visit local GPS ephemeris server, obtain up-to-date GPS almanac data, thereby accelerate GPS position fixing process first.

Local GPS ephemeris server rack is located on the internet, and almanac data wherein has two sources, and data are from GPS official ephemeris server, as the IGS whole world grid of reference, just said GPS

root ephemeris server

3,4,5,7.Another one is the virtual GPS ephemeris generation module of the built-in operation of local GPS ephemeris server.

Generally speaking, local GPS ephemeris server obtains almanac data in real time from GPS official ephemeris server, guarantees the renewal synchronously in real time of local GPS ephemeris data in server and GPS official ephemeris data in server.When local GPS ephemeris server with after GPS official ephemeris server is connected because some reason disconnects, the GPS almanac data of local GPS ephemeris server can switch to the virtual GPS almanac data at once, with continuity and the reliability of assurance GPS almanac data.

The data of virtual GPS ephemeris obtain from the built-in virtual GPS ephemeris generation module of local GPS ephemeris server.Can provide local GPS ephemeris server 5 days almanac data at most, up to the recovery that is connected of the GPS of GPS official root ephemeris server.

Fig. 2 obtains GPS ephemeris process for the A-GPS end host from local GPS ephemeris server, and step comprises:

105: download up-to-date GPS almanac data to (6) A-GPS end host from (2) local GPS ephemeris server, execution in step 106 after finishing.

After 106:(6) the A-GPS end host has obtained up-to-date GPS ephemeris, convert almanac data to unified GPS module discernible inner ephemeris format, re-use the ephemeris update command of GPS module, almanac data is updated to (6) A-GPS end host.Execution in step 107 after finishing.

107: system can wait for (6) A-GPS end host location, finishes up to the location, and (6) A-GPS end host ephemeris renewal process finishes.

Fig. 3 is that local GPS ephemeris server obtains the ephemeris process from (3,4,5,7) GPS root ephemeris server, and step comprises:

202: local GPS ephemeris server can at first attempt connecting the first-selected GPS root ephemeris server 3 in the tabulation, if can not connect, and execution in step 203.If can connect, execution in step 206.

203: attempt connecting second standby GPS root ephemeris server 4, if can not connect, with regard to execution in step 204.If can connect, execution in step 206.

204: attempt connecting the 3rd standby GPS root ephemeris server 5, if can not connect, if execution in step 205. can connect execution in step 206.

205: attempt connecting n standby GPS root ephemeris server 7, if can not connect, system will jump out the connection task, execution in step 206, if can connect, also execution in step 206.

206: local GPS ephemeris server can judge whether and can carry out communication with GPS root ephemeris server, if can normal communication, and execution in step 208, if can not communication, reporting system obtains the connection failure of GPS root ephemeris server.Execution in step 207.

208: after local GPS ephemeris server and GPS root ephemeris server connected, whether GPS root ephemeris server can be inquired about by system the GPS almanac data that can upgrade.When system detects new almanac data generation, execution in step 209, if do not detect new data updated, Data Update finishes, and waits for next data updating process, execution in step 201.

In the relevant step 207, the course of work of (1) virtual GPS ephemeris generation module:

Virtual GPS ephemeris generation module is a GPS ephemeris forecasting software that moves on the local GPS ephemeris server.Software uses historical GPS almanac data, operation characteristic in conjunction with satellite, algorithm by difference ephemeris correction data (Differential Almanac Correction Data) is inferred the next satellite transit track of several hrs, generates comparatively accurate satellite almanac data.

The virtual ephemeris that infer to generate by software can be kept effective ephemeris of several hrs even tens hours, makes also can obtain accurate almanac data under the situation that local GPS ephemeris server and GPS root ephemeris server disconnect.

Obtain from local GPS ephemeris server at the A-GPS end host, and the almanac data one of importing GPS module has two kinds, Almanac and Ephemeris.Chinese name generally is translated as broadcast ephemeris and accurate almanac:

Almanac (broadcast ephemeris) data are more rough orbit parameters of all satellite situations of reflection, and each satellite all can be broadcasted the Almanac data of all satellites, and the relative out of true of these class data is valid up to some months.

Ephemeris (accurately almanac) data are that ten minutes accurate orbit and clock are corrected information by contrast, each satellite only can be broadcasted the Ephemeris data of oneself, and the term of validity of these class data is about several hrs (content that comprises that depends on broadcast message).The Ephemeris data break upgraded once in average 15 minutes, every broadcasting in 30 seconds once.

In the relevant step 210, the conversion method of almanac data:

The preferred server that almanac data obtains is IGS whole world grid of reference.From the original Almanac almanac data that IGS obtains, 6 the gps satellite almanac datas in front are explained as follows:

The inside satellite numbering

1

2

3

4

5

6

The satellite health degree

0

The satellite trajectory excentricity

0.001639

0.012144

0.016019

0.010332

0.003056

0.007832

The square root of major semi-axis

5153.7

5153.6

5153.7

5153.5

5153.6

Right ascension of ascending node

-4.868

-6.01

-72.959

-5.063

54.98

-68.438

Argument of perigee

20.957

-151.82

72.983

55.239

18.166

-21.355

Mean anomaly

25.452

74.835

84.277

-99.559

-165.526

-168.155

Almanac constantly

61440

To 54 degree dip migrations

1.0451

-0.1861

-0.516

-0.241

0.378

-0.1305

Equator I speed

-0.00044

-0.00045

-0.00049

-0.00045

-0.00047

-0.00049

Satellite clock correction

0

The satellite clock drift

0

GPS week

1731

These data are to describe the critical data of gps satellite orbit.

According to the original Almanac data of satellite, can dope gps satellite at several hrs next, even tens hours running orbit.

According to the original Almanac data of satellite, can obtain the observability prediction of gps satellite in following 24 hours.

By using GPS ephemeris update command, to the A-GPS end host, the cold start-up process of system will convert warm start to above-mentioned Almanac Data Update, thereby the time of start for the first time can be shortened greatly.

Further, can be with the accurate almanac of the Ephemeris(of gps satellite) be updated to the A-GPS end host, the process of the satnav locking of can further accelerating to start shooting for the first time shortens the time of start for the first time.

Be the accurate almanac of gps satellite Ephemeris(that 2013-03-10 0:30 in morning obtains from (3,4,5,7) GPS root ephemeris server below) part

* 2013 3 10 0 30 0.00000000

PG01 -4238.806870 -14648.089913 -21767.768287 6.213531 9 10 9 185

PG02 -18430.600125 14005.325091 12734.023677 421.665203 7 7 9 185

PG03 8769.176587 -23998.363421 6301.471878 178.490494 8 6 8 170

PG04 -25956.152269 6264.296321 643.565173 156.746189 5 8 10 196

PG05 -6176.671099 15283.380947 20766.453950 -387.151521 10 6 7 215

PG06 13593.297005 -19504.175506 11565.689192 321.106033 8 6 6 197

PG07 -19608.594128 -7471.019306 16496.136938 189.380853 6 6 7 195

PG08 -25738.017560 -2100.714400 7523.575627 5.034836 8 10 8 188

The conversion of gps satellite almanac data form,

From the almanac data that GPS root ephemeris server obtains, be the ephemeris forecast file current.alm of a Yuma form.Current.alm is the file of a plain text txt form, and the Almanac data of current each satellite have clearly been described in the inside.

The Almanac data are made up of 448 16 data by sign pattern, have represented the relative status of 32 different satellites, 14 data of every satellite.

The actual valid data of Almanac data are 896 bytes, and its timeliness phase is the several months.

The form that in local GPS ephemeris server, needs the data-switching with the ephemeris file to become system to identify.

Almanac data with the 3rd satellite in the current.alm file is example below:

******** Week 707 almanac for PRN-03 ********

ID: 03

Health: 000

Eccentricity: 0.1602125168E-001

Time of Applicability(s): 147456.0000

Orbital Inclination(rad): 0.9334536747

Rate of Right Ascen(r/s): -0.8617501811E-008

SQRT(A) (m 1/2): 5153.613281

Right Ascen at Week(rad): -0.1274126090E+001

Argument of Perigee(rad): 1.273876294

Mean Anom(rad): 0.1450665333E+001

Af0(s): 0.1792907715E-003

Af1(s/s): 0.3637978807E-011

week: 707

The almanac data of these textual forms with the IRN-200D-001 standard, is changed.

With the data instance of the 3rd satellite, the data after the conversion comprise the message body that a length is 30 (0x1E) byte, reply to be numbered 0x0E, i.e. Almanac data.0x03 number satellite data is: 97 C1....BB 3A, last several is check code.

A0 A2 00 1E 0E 03 97 C1 43 73 78 63 F6 BD FD 22 00 A1 0C B9 CB 69 6D 2C 0F 4D 46 B3 D8 5C 00 23 BB E4 0D 4A B0 B3

Data after converting can be saved in local GPS ephemeris server, wait for that the A-GPS end host reads.After the A-GPS end host gets access to these data, by carrying out the 0x82 order current Almanac data are written to the GPS module with binary form again, wait for GPS module locking satellite and quick location.

Claims

1. A system for updating GPS ephemeris quickly and reliably, comprising a plurality of A-GPS terminal hosts (6) and a local GPS ephemeris server (2); it is characterized in that: said local GPS ephemeris server (2), Contains a virtual GPS ephemeris generation module (1) inside; Described virtual GPS ephemeris generation module (1) is a GPS ephemeris prediction module running on the local GPS ephemeris server; GPS ephemeris prediction module uses historical GPS ephemeris Based on the almanac data, combined with the operating characteristics of the satellite, the algorithm of the differential ephemeris correction data is used to estimate the satellite trajectory in the next few hours, and generate more accurate satellite ephemeris data.

2. system according to claim 1, it is characterized in that: each A-GPS terminal host (6) accesses the local GPS ephemeris server (2) on the Internet by the connection mode of GPRS or WIFI, obtains the latest GPS ephemeris data.

3. Utilize the method for GPS ephemeris update by the system of claim 1, it is characterized in that the method comprises A-GPS terminal host computer (6) to obtain GPS ephemeris from local GPS ephemeris server (2), local GPS ephemeris Server (2) obtains ephemeris from GPS root ephemeris server (3,4,5,7), two processes:

A-GPS terminal host computer (6) obtains GPS ephemeris process from local GPS ephemeris server (2), and step comprises:

101: The A-GPS terminal host (6) is powered on, and each part of the system is initialized;

102: Judging whether the satellite ephemeris in the GPS module needs to be updated, if no update is required, step 107 is performed, and if update is required, step 103 is performed;

103: Determine whether the GSM/GPRS or WIFI of the terminal has been connected to the Internet; if connected to the Internet, execute step 104, and if not connected to the Internet, execute step 107;

104: After the terminal is connected to the Internet, it will connect to the local GPS ephemeris server (2), and perform step 105 after confirming the correct connection;

105: Download the latest GPS ephemeris data from the local GPS ephemeris server (2) to the A-GPS terminal host (6), and execute step 106 after completion;

106: After the A-GPS terminal host (6) obtains the latest GPS ephemeris, it converts the ephemeris data into a unified internal ephemeris format recognizable by the GPS module, and then uses the ephemeris update command of the GPS module to update the ephemeris Data is updated to the A-GPS terminal host (6); after completion, step 107 is performed;

107: The system will wait for the A-GPS terminal host to locate (6), until the positioning ends, and the A-GPS terminal host (6) ephemeris update process ends;

(2) The process that the local GPS ephemeris server obtains the ephemeris from the GPS root ephemeris server (3,4,5,7), and the steps include:

201: The local GPS ephemeris server (2) connects to the GPS root ephemeris server (3, 4, 5, 7) every 2 seconds, and when the timing reaches 2 seconds, execute step 202;

202: (2) The local GPS ephemeris server will first try to connect to the preferred GPS root ephemeris server (3) in the list, if it cannot be connected, perform step 203; if it can be connected, perform step 206;

203: try to connect the second backup GPS root ephemeris server (4), if you can't connect, just execute step 204; if you can connect, execute step 206;

204: try to connect to the third backup GPS root ephemeris server (5), if you can't connect, execute step 205; if you can connect, execute step 206;

205: try to connect to the nth backup GPS root ephemeris server (7), if it cannot be connected, the system will jump out of the connection task and perform step 206, if it can be connected, also perform step 206;

206: The local GPS ephemeris server (2) will judge whether it can communicate with the GPS root ephemeris server (3, 4, 5, 7). If it can communicate normally, execute step 208. If it cannot communicate, notify the system to obtain the GPS root The ephemeris server (3,4,5,7) failed to connect; go to step 207;

207: The system will start the virtual GPS ephemeris production module, through the GPS ephemeris data obtained before, and according to the algorithm of differential ephemeris correction data, obtain accurate GPS ephemeris, and execute step 210 after completion;

208: After the connection between the local GPS ephemeris server (2) and the GPS root ephemeris server (3,4,5,7) is established, the system will query whether the GPS root ephemeris server (3,4,5,7) can be updated GPS ephemeris data; when the system detects that new ephemeris data is generated, step 209 is performed, if no newly updated data is detected, the data update ends, and the next data update process is waited for, and step 201 is performed;

209: Enable the ephemeris data download program, and completely download the new ephemeris data to the local GPS ephemeris server (2);

210: After the local GPS ephemeris server (2) obtains new GPS ephemeris data from the GPS root ephemeris server (3, 4, 5, 7) or the virtual GPS ephemeris generation module (1), it will convert the data, Convert it into an array of ephemeris that can be recognized by the GPS module, save it in the local GPS ephemeris server (2), wait for the A-GPS terminal host (6) to read it, execute step 201, and carry out the next cycle.

4. The method according to claim 3, characterized in that: A-GPS terminal host (6) updates the GPS ephemeris data to the A-GPS terminal host (6) by using the GPS ephemeris update command, and the system's The cold start process is converted into a warm start.