WO2003005055A1

WO2003005055A1 - Gps receiver and method for determining position of a wireless terminal

Info

Publication number: WO2003005055A1
Application number: PCT/KR2002/001076
Authority: WO
Inventors: Sangjeong Lee; Taekyung Sung; Chansik Park; Seokbo Son; Ilheung Choi; Youngbaek Kim
Original assignee: Navicom Co., Ltd.
Priority date: 2001-06-05
Filing date: 2002-06-05
Publication date: 2003-01-16
Also published as: KR100448574B1; KR20020092718A

Abstract

The present invention provides a method for determining a position being capable of reducing time required for acquiring measured values, and thus substantially increasing a receiving-sensitivity of GPS signal for terminals. Since navigation data is included in auxiliary information provided from a base station to a terminal, the terminal may disregard the effect of the bit phase change, therefore,the number and time for data processing can be reduced. Furthermore, since information on a cell coverage of the base station is included in the auxiliary information, the base station can reduce the code searching range in use in determining a position.

Description

GPS Receiver and Method for Determining Position of a

Wireless Terminal

TECHNICAL FIELD

The present invention relates to a positioning system and method, and more particularly, to a Global Positioning

System (GPS) receiver and a method for positioning by using GPS signals with the support of a wireless communication network.

BACKGROUND ART

Positioning systems for determining a position^' of a vehicle are widely used in various fields. One of the most popular positioning systems is global positioning system

(GPS) .

Source signals used for positioning are provided from

a plurality of GPS satellites that make rounds following the circular orbits at altitudes of about 20,200 km, and GPS

receivers receive GPS signals from at least 4 visible satellites among GPS satellite constellation and calculates

the position of themselves.

A GPS receiver calculates a range and a range-rate between the receiver and each satellite by calculating a time delay and a Doppler-shift of the signals from each

satellite, and obtains the position and velocity of each satellite from a navigation data acquired by demodulating the signals received. Once the position and velocity information with regard to more than 4 satellites is obtained, the receiver can determine its own position and

velocity.

The GPS signals are generated by a method in which a navigation data of 50 Hz spreads by using a specific pseudo random noise (PRN) code of each satellite, and, subsequently, are modulated into carrier signals of 1.5 GHz by using a

binary phase shift keying (BPSK) modulation technology. Thus, to extract the navigation data from the GPS signals, the receiver should eliminate the PRN code and the carrier

signal upon receiving the GPS signals. Doppler information regarding a magnitude and a

direction of the Doppler-shift is required to eliminate the carrier signals. In general, when the receiver is fixed in position, the magnitude of the Doppler-shift caused by a

satellite movement is not larger than 5kHz. Such Doppler information may be calculated by periodically searching scheme. Codes incorporated in the GPS signals comprises a coarse acquisition code (C/A code) widely known as a "civilian code", and a precise or protected code (P code) also widely known as a "military code". Each satellite has its unique code. Codes can be eliminated from the GPS signals by a method in which the GPS receiver generates the same code with the code of the corresponding satellite, and performs a convolution process simultaneously with a Doppler searching procedure.

As described above, the navigation data may be extracted after eliminating the PRN code and the carrier signals. Under the navigation data specification, a frame

consists of five subframes, and a superframe consists of 25 frames. Each of Subframes 1, 2 and 3 contains information on

time and position of a transmission satellite, and thus, subframe 1, 2 and 3 of each satellite have distinct information. Subframes 4 and 5 contain information common

for all satellites. Therefore, subframes 4 and 5 of each satellite have the same data. Positioning can be performed after demodulating the

navigation data and obtaining positions for more than 3~4 satellites.

Meanwhile, there have been increasing needs for a wireless positioning system for determining the position of a wireless communication mobile station by using a wireless communication network. Particularly, a wireless positioning

system has been most needed in the emergency rescue service field. On June 12, 1996, Federal Communication Commission (FCC) adopted a standard that all wireless communication service providers including a cellular communication system operator and a personal communication system (PCS) operator

are requested to transfer a call to the Public Safety Answering Point (PSAP) without any procedure for an authentication or a credit investigation when there is an

emergency rescue request call. According to the standard, the service providers are also requested to provide position information of a wireless communication mobile station with

an accuracy of about 50 m for 67% of emergency rescue request calls, and about 150 m for 95% of all emergency rescue request calls. Therefore, the announcement of the standard has spurred the research for the positioning system based on the wireless communication network.

The positioning system based on the wireless communication network may break down into three methods : a network positioning method using only communication network system; a GPS positioning method using only GPS system; and

a hybrid positioning method using both the communication network system and the GPS system.

The network positioning method utilizes a geolocation method for determining the position by using a trigonometry based on a plurality of base stations. The network positioning method is divided into a remote positioning method and a self-positioning method.

In the remote positioning method, a plurality of base

stations receive a signal transmitted from the mobile station, and the position is finally calculated in a central

site . The remote positioning method bears an advantage that a mobile station structure needs not to be modified while it has disadvantages that the communication network system should be changed and the mobile station side cannot obtain its own position.

In the self-positioning method, mobile station performs a positioning procedure by using signals from a plurality of the base stations. This method has advantages

that it can be implemented by modifying the mobile station structure without a significant modification of the communication network system, and further the position of the mobile station is obtainable. On the contrary, the self- positioning method has disadvantages that positioning is difficult in the condition that the number of the base station with high hearibility decreases, and an error of the position may increase due to an error of non line of sight (NLOS) .

Meanwhile, in the GPS positioning method, the wireless communication mobile station transmits the data measured by a GPS receiving circuit thereof to a central control center via the wireless communication network. This method has an

advantage that the method can be implemented without a

significant modification to the communication network system. This method, however, has disadvantages that power consumption of the mobile station and a frequency

interference may increase since the mobile station involves with two systems, and positioning is not readily obtainable in indoor space where signal strength is dim. Furthermore, a time required for obtaining an initial position in the GPS positioning system is about 1 minute, which may be allowable

in an application of a general navigation system, however, may be too long in an emergency condition like the emergency

rescue request. The hybrid positioning method can cancel out the disadvantages of the network positioning method and the GPS positioning method by appropriately combining both the methods. In hybrid positioning method, the positioning is performed by the network positioning method in normal condition, but the GPS positioning method is used in the condition that the number of the neighboring base stations or the base stations with the high hearibility is insufficient. The hybrid positioning method, however, has a disadvantage that the mobile station structure becomes complex and the power consumption increases.

Recently, in order to overcome the problems of the prior arts, a network-assisted GPS positioning method has been developed in which roles of the base station and the mobile station are divided in processing the data in obtaining the position on the basis of the GPS signals. In accordance with the network-assisted GPS positioning method, the base station transmits an auxiliary data required for improving the GPS positioning speed to the mobile station

via the wireless communication network, and the mobile station calculates a pseudo-range per each satellite by using the auxiliary data. The auxiliary data may include the

satellite position data at measurement time and the Doppler

information of the satellite and the like. The mobile station may transmit the positioning data to a central control center after directly positioning based on the pseudo-ranges for the satellites. As an alternative, the mobile station help the base station, a mobile switching center and the central control center to perform the positioning by providing the pseudo-ranges for the base

station. The network-assisted GPS positioning method has advantages that it is possible to reduce the positioning time, to perform the positioning inside a room with weak

signal intensity, and to improve the positioning accuracy compared to the prior network positioning systems.

Technologies for the network assisted GPS positioning

method may be divided into three fields : the first technology for reducing the time required for a signal acquisition and the positioning procedure in the GPS receiver embedded in the mobile station by providing an appropriate auxiliary data from the base station to the

mobile station via the wireless communication network; second technology for improving a receiving sensitivity of

the GPS signals for performing the positioning indoor; and third technology for reducing the power consumption of the system.

The satellite position and Doppler information are required for reduction of a signal acquisition time, i.e.,

the time to first fix (TTFF) . The satellite position may be calculated on the basis of a satellite ephemeris data and a GPS time data, and the Doppler information may be calculated from a clock drift of the a receiver local oscillator and a velocity of the satellite and the mobile station. Therefore, the base station provides the auxiliary data including a time information, a frequency information and the Doppler

information for the mobile station in the network-assisted GPS positioning method.

In the network-assisted GPS positioning method, the time information is a fundamental data for synchronizing the mobile station and the base station with a reference time called as universal time coordinate. A mobile station modem provides the time information synchronized with the base station for the GPS receiver so that the GPS receiver can

obtain the satellite position and reduce a search range for

calculating a code offset. When the base station provides accurate carrier frequency information for the mobile station, it is possible to correct the clock drift of the GPS receiver local oscillator. The method for providing the accurate carrier frequency information is disclosed in U.S. patent No. 5,663,734 granted to the Precision Tracking Incorporated. Furthermore, the method for providing the Doppler information for visible satellites is proposed by the U.S. patent 5,781,156 granted to the Snaptrack, Inc. and U.S. patent 5,663,734 as above.

Meanwhile, the receiving sensitivity of the GPS signals should be improved to successively perform the positioning for indoor application. In order to improve the

receiving sensitivity, in addition to providing the auxiliary information from the base station to the mobile

station as described, there has been proposed a method in which the mobile station performs a plurality of convolution operations or fast Fourier transform (FFT) operations in tracking and demodulating the GPS signals. For example, in U.S. patents Nos. 5,663,734 and 5,781,156 and another U.S. patent No. 5,884,214 of the Snaptrack Inc., it is disclosed a procedure for tracking and demodulating signals by

performing a plurality of the convolution operations and the FFT operations . Another conventional method for improving the receiving sensitivity is an extension of the signal integration time as disclosed in U.S. patent No. 5,884,214. However, it is impossible to perform the signal integration for more than 20 miliseconds in case that the data is unknown since the GPS signals comprise 50Hz data. Furthermore, if there is an error in the Doppler information estimated, the limitation for the signal integration time becomes worse. Two methods may be used to overcome the limitation for the signal integration time. The first method is a correction of the clock drift of the receiver by using the accurate carrier signal of the base station. In addition,

in accordance with the second method, the signals are integrated after being divided into several short time periods and magnitude alone is integrated again hereinafter, or the signals may be searched by estimating a Doppler error in order to prevent a signal attenuation caused by a Doppler

error.

Furthermore, in order to reduce the power consumption of the mobile station with the network-assisted GPS

positioning function, for example, U.S. patents Nos. 5,663,734 and 5,781,156 disclose a circuit capable of selectively supplying the power to a radio-frequency signal input side and a snapshot memory only while receiving the GPS signals, supplying the power to a digital signal processor (DSP) while processing intermediate frequency (IF) data, but not supplying the power to these devices during

another procedure or while the positioning is not required.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a positioning method capable of reducing the signal acquisition time (i.e., time to first fix) and improving the

receiving sensitivity of the GPS signals of the mobile station.

According to an aspect of the present invention, the

base station provides the mobile station with an auxiliary data including a pseudo-range and a time information for the corresponding base station, and a navigation data via a wireless communication network. The mobile station does not

have to consider a bit phase shift by the navigation data in obtaining a C/A code from the GPS signals. In addition, the mobile station can extend the signal integration time to at

least 20 miliseconds. Therefore, the time required for processing the signals can be reduced since the number of

the data process times decreases for the data of a predetermined amount.

In addition, in accordance with the present invention, the auxiliary data includes information on a cell coverage of the base station communicated with the mobile station, and may further include a round trip delay (RTD) information between the base station and the mobile station, and/or a sector information and a relaying equipment (hereinafter

"repeater") information. The base station can reduce the

signal acquisition time by reducing a calculation amount and a code search range during positioning procedure on the basis of the auxiliary data, and can improve the receiving sensitivity.

BRIEF DESCRIPTION OF DRAWINGS The above and other objects and features of the

present invention will become apparent from the following description of a preferred embodiment given in conjunction with the accompanying drawings, in which:

Fig. 1 shows a preferable embodiment of the GPS mobile station according to the present invention;

Fig. 2 is a flow chart illustrating a self-positioning procedure in the GPS mobile station of Fig. 1;

Fig. 3 is a flow chart illustrating a remote positioning procedure in the GPS mobile station of Fig. 1;

Fig. 4 shows a signal process procedure by an intermediate frequency (IF) sampling of Fig. 2 in more detail;

Fig. 5 is a waveform diagram illustrating a structure of general GPS signals;

Fig. 6 is a waveform diagram illustrating a procedure to eliminate a carrier and a navigation data from the GPS signals;

Fig. 7 conceptually illustrates a coherent integration procedure for a received C/A code;

Fig. 8 is a conceptual diagram illustrating a procedure to reduce a code search range on the basis of an estimation of a limitation value of a time delay;

Fig. 9 is a draw for explaining a procedure to interpolate correlation values for points between sampling time in order to determine the point with the highest correlation value;

Fig.10 is a diagram for explaining a positioning auxiliary data from the base station and the usage of the auxiliary data in accordance with the present invention;

Fig.11 is a diagram for explaining a method for calculating a search range used for a calculation of a pseudo-range between a satellite and the mobile station;

Fig.12 illustrates a searching method in the case that information on the pesudo-range is provided by the base station;

Fig. 13 shows an example of a RTD statistical value

collected by the base station;

Fig.14 illustrates the search range for acquiring the second satellite signal in the positioning method using the

pseudo-range pre-calculated for the other satellite; Fig.15 illustrates the search range for acquiring the third satellite signal in the positioning method using the pseudo-range pre-calculated for the other satellite; Fig. 16 shows the search range in the embodiment using

sector information;

Fig.17 illustrates a condition enabling for the mobile

station to receive signals from two base stations; and

Fig. 18 shows a range of a position error in the case that at least two base stations are used.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings .

Fig. 1 shows a preferable embodiment of the GPS mobile station according to the present invention. The GPS mobile station 10 of Fig. 1 includes a modem 12 for transmitting/receiving a wireless signals, an antenna 14 used for transmitting/receiving the wireless signals, and a GPS receiving unit 20. The GPS mobile station can transmit signals to a wireless communication base station

(hereinafter, "the base station") and receive signals from the base station through a wireless communication link, and can receive the GPS signals from a GPS satellite. In the preferable embodiment of the present invention,

the base station 2 is a part of a code division multiple access (CDMA) communication network, which provides a communication service to the mobile station in the

corresponding cell coverage. In particular, a base station transceiver subsystem (BTS) of the base station used in the present invention includes a GPS receiver, and generates, stores and periodically updates positioning auxiliary

information for providing to the mobile station 10 during continuously processing a navigation data. When the base

station transmits a start request command of the positioning to the mobile station 10 or receives a positioning start request from the mobile station 10, the base station 2 provides the positioning auxiliary information for the mobile station 10 so that enables the mobile station 10 to

perform a rapid and ease positioning by means of the auxiliary information. The positioning auxiliary information will be described in more detail below.

Referring to Fig. 1, the modem 12 modulates uplink communication signals into a CDMA signals and transmits modulated signals to the base station 2, and demodulates the CDMA signals transmitted from the base station. The modem 12 and the GPS receiving unit 20 are connected by means of a

serial I/O interface port. If the GPS receiving unit 20 receives a positioning command from the base station, or if the positioning command is applied to the GPS receiving unit 20 by a user or an operation of a program embedded in the

mobile station, the GPS receiving unit 20 receives the positioning auxiliary information through the modem 12 and

receives the GPS signals from the GPS satellites, and determines the position of the mobile station by using the positioning auxiliary information and the GPS signals received.

According to the preferred embodiment of the present invention, the mobile station 10 is designed to include the modem 12 and the GPS receiving unit 20 in one housing of a monolithic construction. However, in accordance with another

embodiment of the present invention, the GPS receiving unit 20 is separately prepared and connected to the modem 12 in the mobile station by means of a serial interface port of the mobile station. The mobile station may be, for example, a cellular mobile phone, a personal digital assistant (PDA) and the like .

In the embodiment as depicted in Fig. 1, the GPS receiving unit 20 comprises a microprocessor 22, a power

controller 24, a frequency synthesizer 26, an antenna 28, a down converter 30, a analog/digital converter (hereinafter "A/D converter") 32, a snapshot memory and a digital signal

processor 36.

The microprocessor 22 performs data communication with

the modem 12, and also performs a power control operation. That is, the microprocessor 22 controls the power controller 24 not to supply or supply minimum stand-by power to the down converter 30, the A/D converter 32, the snapshot memory 34 and the digital signal processor 36, and to supply full power to these parts during a few steps of the whole positioning procedure.

Therefore, the down converter 30, the A/D converter 32, the snapshot memory 34 and the digital signal processor 36

are maintained in a low-power stand-by mode while the positioning is out of operation. If the positioning procedure starts, at first, full power is supplied to the down converter 30, the A/D converter32 and the snapshot memory 34.

The down converter 30 acquires the GPS signals with RF

bandwidth received at the antenna 28, and converts frequency bandwidth of the GPS signals into the intermediate frequency

bandwidth by using a local oscillation signal from the frequency synthesizer 26.

The A/D converter 32 performs a sampling and a

quantizing for intermediate frequency signals (hereinafter "IF signals") from the down converter 30 by using a sampling clock received from the frequency synthesizer 26. The A/D converter 32 stores resultant digital data (hereinafter ^XIF

sampling signals") in the snapshot memory 34. The digital signal processor 36 is supplied with only the standby power while the procedure from the sampling of the GPS signals to a storing of the IF sampling signals is performed.

Meanwhile, the down converter 30 and the A/D converter 32 enter into the low-power standby mode after the IF sampling signals are stored in the snapshot memory, and full

power is supplied for the snapshot memory 34 and the digital signal processor 36.. The digital signal processor 36 calculates the pseudo-range for each satellite by using the IF sampling signals stored in the snapshot memory 34 and the auxiliary information received from the base station through

the microprocessor 22. Appropriate algorithms are programmed in the digital signal processor 36 . The digital signal processor provides pseudo-range information for the microprocessor 22 after calculating the

pseudo-range for each satellite. The microprocessor 22 controls the power controller 24 again to convert the snapshot memory 34 and the digital signal processor 36 to the low-power standby mode after receiving the pseudo-range information. Subsequently, the microprocessor 22 processes the pseudo-range information based on an operation mode. That is, in a self-positioning mode, the mobile station determines its own position, the microprocessor 22 calculates the position of the mobile station by using the pseudo-range information, and displays the resultant position data for the mobile station on a screen or transmits the resulting data to the base station 2. In a

remote positioning mode, a separate central control center

determines the position of the mobile station, the microprocessor 22 transmits the pseudo-range information to the central control center via the base station 2, and

allows the central control center to determine the final position of the mobile station.

Structure of the GPS mobile station shown in Fig. 1 is similar to the structure disclosed in U.S.P.N. 5,663,734 and 5,781,156. The GPS mobile station according to the present

invention, however, differs from those disclosed in the patents in that the type of the positioning auxiliary information received from the base station 2 is different. The positioning auxiliary information in accordance with the present invention, in particular, further comprises a navigation data acquired by the base station, a range of a cell coverage for the base station, i.e., an effective range of the base station, and/or a data on the round trip delay (RTD) between the base station and the mobile station. Accordingly, the positioning procedure in accordance with the present invention presents distinction from the methods as proposed in the above U.S. patents.

Fig. 2 is a flow chart illustrating a positioning

procedure using the GPS mobile station of Fig. 1.

At first, a communication link should be established between the base station 2 and the modem 12 in the mobile station 10 (Step 100) . The mobile station 10 corrects a time error by using the signals transmitted from the base station 2 pursuant to a pre-determined protocol. In this condition, the frequency synthesizer 26 of the GPS receiving unit 20 minimizes a clock drift error and a Doppler shift by sharing a clock with the modem 12 of the mobile station.

Meanwhile, the base station 2, if necessary, can transmit a positioning start command to the mobile station 10 in the state that the communication link is established (Step 102) . The positioning start command has a specific time mode in which the positioning is performed at a specific time, and an immediate mode for immediately performing the positioning procedure. The mobile station 10 transmits an acknowledge signal to the base station in response to the receiving of the positioning start command.

If the specific time is specified in the positioning start command, the mobile station 10 transmits a positioning start notification signal to the base station at the specific time.

As an alternative, the mobile station 10 may transmit a request to start the positioning procedure to the base

station, and the base station 2 transmits the positioning start notification signal to the mobile station 10 after receiving the request.

Subsequently, the mobile station 10 receives the GPS signals, and stores the IF sampling signal in the snapshot memory 34 (Step 104) . At the same time, the base station 2 provides the positioning auxiliary information for the mobile station 10 (Step 106) . The positioning auxiliary

information prepared at the base station 2 is transmitted to the modem 12 of the mobile station 10 and then transferred to the microprocessor 22 of the GPS receiving unit 20 by means of a serial communication (Step 108) .

In accordance with the preferred embodiment, the auxiliary information for use in positioning in the GPS receiving unit 20 of the mobile station 10 includes a first part provided by the base station 2 and a second part pre- calculated and stored. The variety of the auxiliary information is disclosed in table 1.

TABLE 1

Type of the auxiliary information Usage

Satellite code Selecting satellite transmitting GPS (SV ID) signal to be processed

Pseudo-range between Initial value of mobile station base station and pseudo-range for corresponding satellite ( p_BS) satellite

Satellite orbit Calculating Doppler shift for (Ephemeris) corresponding satellite

Eliminating navigation data from

Navigation data signals received at mobile station

Items

Setting time for calculating provided satellite position from the base Setting positioning time

Time information station Setting reference time for calculating mobile station pseudo- range

Effective range of

Calculating code search range base station (R_B5)

Reducing code search range

Round trip delay Correcting time error due to distance (RTD) time between base station and mobile station

Clock error of

Items Calculating code search range mobile station already

Clock error of base known Calculating code search range station

Meanwhile, an effective range (R_Eejffl(β,)of a repeater may be provided in place of or along with a cell coverage, i . e . , an effective range of the base station for reducing the code search range . Furthermore, sector information can be included in the positioning auxiliary information. The positioning auxiliary information may further include a position of the base station (or repeater) communicating

with the mobile station, information on whether communication device is the base station or the repeater. In particular, the effective range (R) of the base station in case that information on the repeater is unknown or the

repeater is not used may differ from the effective range ( R_BS) of the base station in case that the base station is used.

The GPS receiving unit 20 processes the IF sampling

signals and calculates pseudo-ranges for all or part of visible satellites after collecting the IF sampling signal at step 106 and step 108 and receiving the positioning auxiliary information from the base station 2 (Step 110) . Upon calculating of the pseudo-range, the microprocessor 22 calculates the position of the mobile station based on the

pseudo-ranges for visible satellites and ephemeris data of the satellite, and transmits data on the position of the mobile station to the base station 2 (Steps 112 and 114) .

Referring to Fig. 3 explaining the remote positioning, the calculated pseudo-range information is transferred to the central control center via the base station 2 so that the central control center can calculate the position of the mobile station.

Fig. 4 shows a signal processing by an intermediate frequency (IF) sampling of Fig. 2, i.e., step 110 in more detail. Referring to Fig.4, at first, a C/A code for a visible satellite is generated (Step 150) . Generally, the C/A code is a pseudo noise (PN) code having 1 MHz frequency periodically repeating every Imilisecond, i.e., every 1,023 bits. In step 150, the C/A code is generated at a PN code generator in the digital signal processor 36. As an alternative, the C/A code may be obtained from a look-up table loaded at a memory. After the C/A code is generated, the C/A code included in the received GPS signals (hereinafter "the received C/A code") is recovered and coherent-integrated by means of the IF sampling signal stored in the snapshot memory 34 (Step 154) . Furthermore,

the pseudo-range is determined by synchronizing timing between a generated C/A code and an integrated C/A code referring to a time tag in the navigation data bit received

at the base station 2, and subsequently calculating a code delay time between two codes (Steps from 156 to 168) .

Steps from 156 to 168 will now be described in more

detail. In general, the GPS signals consist of the navigation

data, the C/A code and the carrier. A phase of the carrier is inverted when the navigation or the C/A code shifts a logic state. Meanwhile, the carrier is first eliminated from the GPS signals since the pseudo-range is calculated by

means of a delay time of the C/A code included in the GPS signals. Generally, a change of bit phase due to the navigation data should be considered for eliminating the carrier. That is, in case that the navigation data of 50Hz frequency remains, it is impossible to extend an integration time to more than 20ms in the coherent-integration procedure, and thus there is a limitation in improving the receiving sensitivity by means of the integration.

In the GPS mobile station shown in Fig. 1, however, the carrier and the navigation data can be eliminated from

the GPS signals, more particularly, from the IF sampling signal since the digital signal processor 36 receives the navigation data from the base station 2 by way of the modem 12 and the microprocessor 22 as shown in Fig. 6. Referring

to Fig. 6, after the navigation data are eliminated, all the C/A codes have identical phase. Therefore, the change of bit phase due to the navigation data is no longer a concern, and thus, data processing time for a specific data can be

reduced since the integration time can be extended to more than 20ms. For example, the data processing time in case with the 100ms integration time can be reduced to 1/10 of

the case with the 10ms integration time, since if a data for 1 second should be processed, 10 blocks and 100 blocks are generated in the former case and the latter case respectively. The Doppler shift should be eliminated from the GPS signals along with the carrier. The method for eliminating the Doppler shift is widely known to those who skilled in the art, and thus detailed description therefore will be omitted

The code delay time can be calculated by confirming a correlation with a C/A code generated by the convolution

operation since only the received C/A code remains after eliminating the navigation data and the carrier from the GPS signals. Particularly, the correlation between the generated

C/A code and a received C/A code coherent-integrated is used in order to improve the receiving sensitivity.

Jig. 7 illustrates a coherent integration procedure for the received C/A code. Referring to Fig. 7, the received C/A code is divided by one period unit and summed in a

preferred embodiment of the present invention. If the GPS signals of 1 second are stored in the snapshot memory, 1000 periods of the C/A code can be added during the coherent integration, and thus the C/A code may have 1000 times

larger amplitude compared to that of prior to the integration (Step 154) . The receiving sensitivity can

substantially be improved since the convolution operation is performed on the basis of higher-intensity signals. In Fig. 5, Fig.6 and Fig. 7, a pulse presents one period of the C/A code.

Referring back to Fg.4, in step 156, the GPS receiving unit of the mobile station calculates a timing and determines the search range in ^' order to acquire the correlation value by means of the integrated C/A code and

the received C/A code. In addition, the GPS receiving unit finds a peak correlation value while searching the C/A code in the search range by the convolution operation, and

coherent-integrates the correlation value (Step 158 and 160) . The procedure from step 152 to step 160 is repeatedly performed until the searching process for whole search range ends (Step 162) . The search for the whole search range of the C/A code

is needed according to a prior art using a conventional convolution operation. In accordance with the present invention, however, a time delay search range can be significantly reduced by using the pseudo-range (or along with the RTD information or the sector information) from the base station, and thus calculation time for a time delay can

be reduced. For example, if a marginal value of the time delay can be estimated by means of the positioning auxiliary information as shown in Fig. 8, it is sufficient to perform the code search within the marginal value since real value of the time delay may be within the marginal value. The marginal value of the time delay for use in reducing the search range can be estimated on the basis of the RTD information, the sector information for the corresponding

cell, the pseudo-range to the base station and the like. The method for estimating the marginal value may be described below in more detail.

The GPS receiving unit determines the pseudo-range after searching for whole search range. A resolution power of the calculated time delay value may be determined according to the sampling frequency, and thus a positioning error may increase in case of low sampling frequency. In order to overcome this problem, the GPS receiving unit in

accordance with the present invention determines the point with highest correlation value by interpolating the correlation value between sampling points, and determines a corresponding pseudo-range value (Step 164 and 166) . The procedure according to the steps from 150 to 166 is sequentially applied to each of the visible satellites (Step 168) .

Navigation data generation and transmission in the base station

Time synchronization is necessarily required in order

for the base station 2 to provide the navigation data and for the mobile station 10 to use the navigation as the

positioning auxiliary data. That is, signal loss may occur if synchronization is not achieved in applying the navigation data transmitted from the base station 2 to the IF signal collected in the mobile station 10. Therefore, it is required to synchronize the time the mobile station 10 collects the IF signal with the time the base station 2 acquires the navigation data. In the present invention, the base station 2 attaches a time-tag at the acquired

navigation data and transmits it to the mobile station 10, and the mobile station 10 synchronizes collection time of the IF signal based on the time-tag. In general, a phase difference exists in the navigation data received from each satellite even though the navigation data are received at the same time since the distances between the GPS receiver and each satellite vary. Thus, the mobile station 10 first calculates a bit phase at a collection start time of the navigation data before using the navigation data. The base station 2 has the pseudo-range for each satellite and the collection time of the navigation data, and the pseudo-range corresponds to the time difference between a signal transmission and receiving times .

Thus, the signal transmission time of a satellite can be

expressed as Equation 1. [Equation 1]

SVi rnSVi _ rp PβS trans ^■'^■received ,-r '

wherein, T^_m is the signal transmission time of the i- sn th satellite, T_received is the signal receiving time and ^-~ is

the pseudo-range between the base station and the i-th satellite.

The bit phase can be obtained from the signal

transmission time since the signals transmitted form the

satellite is synchronized with a GPS reference time. The bit

phase can finally expressed as Equation 2.

[Equation 2]

BP_m = fr{ _tZ/ 20msec} = BP^ +σ_BSclock , wherein, o^~ _BSclock ^^{s an} error occurred by the time difference between the base station clock and the GPS

reference time.

The bit phase as Equation 2 is calculated on the basis

of the base station 2, and thus, the bit phase at the mobile

station side may contain a time synchronization error

occurred from a distance difference. Therefore, the time

synchronization error will be corrected by means of the RTD

information in the present invention, and the resulting bit

phase information used in the mobile station can be

expressed as Equation 3.

[Equation 3 ] BP_MS = BP_BS - RTD + σ_BSclock + σ_Msdock = BP_BS - RTD + σ_ohck , wherein, <?_clock presents a clock error of the mobile

station (MS) and the base station (BS) . Reduction of the code search range by means of the RTD

A tracking and acquisition of the carrier and the code

for the satellite signal should be first performed to calculate the distance between the satellite and the mobile station for use in determining the mobile station's position.

The code from the GPS signal may be acquired by executing the convolution operation for the received signal from the satellite and the generated signal in the mobile station during a code period. If no additional information is provided by the base station, the whole range of the signals for 1 ms, i.e., the C/A code period of the GPA signals should be searched. Thus, provided that a code period

comprises of m number of samples, 2 ² times of addition and multiplication operation are required for calculating the correlation value. According to the present invention, however, the time required for the code search can be substantially reduced by also providing an auxiliary information including the RTD information for the mobile station.

Fig.10 is a diagram for explaining a positioning

auxiliary data from the base station and the use of the auxiliary data in accordance with the present invention. In

Fig. 10, the symbol "SV1-SV3" denotes the satellites, "BS" means the base station, "Repeaterl~Repeater3" means the repeaters, and "MS1~MS4" means the mobile station,

respectively. In addition, the symbols " p_BS ", " p_MS " ', R_BS ", " R_Repeater "^', " R ", and " R_RTD " represent a pseudo-range between a

satellite and the base station, a pseudo-range between the satellite and the mobile station, an effective range of the base station, an effective range of the repeater, an effective range of the base station in case that repeater information is unknown, and a distance corresponding to the

RTD information respectively.

Use of the pseudo-range p_π/, calculated on the basis of

the base station

Provided that the pseudo-range calculated at the base station is provided for the mobile station, it is unnecessary to search the whole search range of the C/A code

one period. That is, the mobile station should search only a part of the C/A code based on p_BS instead of the whole search, range since the mobile station is located near to the corresponding base station, and thus there is little difference between p_BS and p_MS . The search range is

determined on the basis of a distance difference and a time synchronization difference between the mobile station and the base station.

Fig.11 is a diagram for explaining a method for calculating a search range used for a calculation of p_MS . The symbol of Θ_BS in Fig. 11 represents an elevation angle of the satellite relative to the base station. Maximum error of the pseudo-range due to the distance difference between the base station and mobile station is expressed by R_BS cos θ_MS)obtained by performing the orthogonal projection of the effective range R_BS of the base station to the vector directed from the base station to the satellite. A search reference point, i.e., a phase of the C/A code, will be expressed as Equation 4.

[Equation 4]

_PBS = fr{p_Bs l^c_Λ - )} , wherein, "fr{}" is a function calculating a value

below decimal point, " λ_CA " represents a wavelength of the C/A code and "C" is the speed of light. The search range can be calculated on. the basis of the time synchronization error between two systems and R_Bs cos(θ_MS) , and the C/A code phase T_p at the mobile station 10 will be expressed as Equation 5.

[Equation 5]

^T _PBS ~ R_BS ∞<Θ_BS) - σ_clock < T_PMS ≤ T_PBS + R_BS cos^) + σ_clock , wherein, o_clock represents the time synchronization error occurring between two systems .

Fig.12 illustrates a searching method in the case information on the pseudo-range is provided by the base station. Referring to Fig. 12, the code search is performed by executing the convolution operation for the generated C/A

code and the received C/A code integrated within the search range defined as Equation 5.

Provided that a repeater is installed inside the cell coverage of the base station and the mobile station can not confirm which repeater communicates with itself, it is preferred to use "R" shown in Fig.10 as the effective range

of the base station instead of " R_BS " . The search range may be extended since the value of "R" is larger than "R_B5 " .

Use of the distance information corresponding to the RTD

The RTD is information on a distance between the base station and the mobile station, and thus the base station

may already have or easily obtain the RTD. If the mobile

station is provided with the RTD information or the distance information corresponding to the RTD from the base station, the mobile station can further reduce the search range. That

is, the mobile station sufficiently searches within

R_RTD instead of the entire effective range of the base station, and thus the search range will be expressed as Equation 6. [Equation 6]

T_PBS - R_RTD ∞S(Θ_BS) - σ_clock ≤ T_Pm ≤ T_PES + R_RTD ∞s(θ_BS) + σ_clock . Signals passing through the repeater may have larger RTD value than signals not-passing through the same. Meanwhile, if a plurality of repeaters is installed inside the cell coverage, it can be known which repeater passes

through a communication link by means of a RTD statistical value .

Fig. 13 shows an example of a RTD statistical value collected at the base station. For the signals passing through the repeater, the search reference point T should

be calculated by means of the pseudo-range p_Repeater and the elevation- angle θ_Repeater based on the position of the repeater, and the effective range R^^_ter °f the repeater. The search

reference point and the search range of signals passing through the repeater are expressed as Equation 7 and

Equation 8 respectively. [Equation 7]

^r _∞

^' Q} /

[Equation 8 ]

P_{Rcpe r} ~ R<= peater ^C0S( Re peater) ^~ ° clock " ~ Pa_peet , Repeater ^C0$(P Re peater) + ° clock

, wherein, the effective range R_Kepeater f the repeater can be

approximately rewritten as Equation 9 by using the RTD information and a time delay D_Repeater of optical cable between

the base station and the repeater. [Equation 9]

^■"^■Re peater ^-RTD ^REpeater

Use the pre-calculated pseudo-range for another

satellite

When the mobile station calculates the pseudo-range for another satellite after calculating the pseudo-range for the first satellite, the search range can be further reduced in satellite signal acquisition procedure by using the pre- calculated pseudo-range for the first satellite. In

accordance with this embodiment, after obtaining the pseudo range for the first satellite, the mobile station determines whether the mobile station is located in nearer side to the satellite than the base station by comparing the base

station pseudo-range p_BM and the mobile station pseudo-range p_MS , and can limit the search range based on the determination result.

Fig.14 illustrates the search range for acquiring the second satellite signal in the positioning method using the pre-calculated pseudo-range for another satellite. Referring to Fig. 14, the first satellite SVl and the second satellite SV2 are projected in a 2-dimensional plane centering on the base station. The symbols in Fig. 14, Pi , ψi , p_B ^J , P_SV] , ^^J

and θ_B ^J represent a i-th position, an azimuth of the i-th position, a pseudo-range between the base station and a j-th satellite, a projection position of the j-th satellite, an azimuth of the j-th satellite and an elevation angle of the

j-th satellite, respectively.

If p_B ^r is smaller than p^² in Fig. 14, the mobile station will be located in a semi-circle region (the shaded region) adjacent to the first satellite SVl of the effective range of the base station, and thus, it is sufficient to

search the shaded semi-circle region for acquiring signals from the second satellite SV2. Though the search range may vary depending on the position of the second satellite, the maximum and minimum value of the pseudo-range in the semi¬

circle region may be obtained respectively. The maximum and minimum value of the pseudo-range will be one of four points

including two cross points ( P₃,P₄) at a circle intersect a line dividing the circle into two semi-circles, the

intersection point P₂ of the circle and a straight line directing to the line-of-sight of the second satellite SV2,

and a center point P_x , i.e., a position of the base station, respectively. Therefore, the maximum and minimum value of the pseudo-range can be determined by calculating distances

from the second satellite SV2 to four points P_λ ~ P_Λ , and comparing the calculated distances. The distance from the satellite to each satellite can be expressed by Equation 10. [Equation 10] r s^v.¹ = -\\ ^rPι —- rP s,v-.

= {(R_BS cosfø) -

+ (R_BS sinfø) - p i cos( ² )sin«² )ff^/2 The search range will be determined by the maximum

value MAX{r^^τ ) and the minimum value MIN r^ ²) , and further be expressed by Equation 11. [Equation 11]

≤ T + {MAX(r^) - p^s } ₊ σ_cl0Ck

In case the pseudo-range of the second satellite is calculated, the mobile station can further reduce the search range for acquiring the third satellite signals.

The search range for acquiring the third satellite

signals is shown in Fig. 15. As similar to the method according to Fig. 14, maximum and minimum value of the

search range for the third satellite can be determined by calculating and comparing distances from the third satellite

to four points P ~ P . If fourth satellite's signals need to be acquired subsequently, the required search range can be further reduced in a similar manner. Therefore, calculation

volume can be reduced and the possibility for miscalculating the C/A code phase due to noise can be accordingly reduced.

Use of the sector information

The sector information may be used as one of the

positioning auxiliary data. In general, three sectors exist for one base station. In accordance with the present invention, the search range can further be reduced by means of the sector information. A method for reducing the search

range by using the sector information can be implemented in

a similar manner as the method using the pre-calculated pseudo-range. The search range according to this embodiment is illustrated in Fig. 16.

In case of using the sector information, the mobile station can reduce the search range from the searching

procedure for the first satellite signals. In Fig. 16, a region the solution of the mobile station position can exist

is defined to an inside region of a gray fan-shaped sector. The maximum and minimum value of the pseudo-range will be one of four points including two cross points ( P₃,P₄) at circle intersects a line dividing the sector, the

intersection point P₂ of the circle and a straight line directing to the line-of-sight of a satellite, and a center

point P_x , i.e., a position of the base station, respectively. Therefore, the maximum and minimum value of the pseudo-range can be determined by calculating distances from the second satellite to four points, and comparing the calculated distances. Furthermore, from the second satellite, the necessary signals can be more effectively acquired by considering the pre-calculated pseudo-range for the other satellite and searching the cross region.

Reduction of the search range for the correlation value by means of more than two base station

The description mentioned above is for reducing the search range by means of the RTD in case the mobile station communicates with one base station. However, the search range may extend as the RTD value increases. In case the mobile station 10 is located far away from the communicating base station, the mobile station may be adjacent to the other base station, and thus a communication possibility with the other station may increases. Therefore, the additional measurements for the corresponding satellite can be used in reducing the search range. That is, in case the

mobile station receives signals from at least two base stations shown as Fig. 17, the mobile station can further reduce the C/A code search range. The position information

obtained according to this procedure, however, may include an error due to a non line-of-sight propagation and multi

path effect and the like, and thus the other solution as presented the quadrangle region in Fig. 17 is additionally provided.

Use of two base stations

Given that the mobile station MS communicates with the

first base station BSl, and the RTD between the first base station BSl and the mobile station MS is already known, the

distance ?} between the first base station BSl and the mobile station MS and the distance r₂ between the second base station BS2 and the mobile station MS will be expressed by Equation 12 respectively. [Equation 12] ι = RTD C ^r2 ~ ^r\ ^"t ^* T + (-{βpNoffsen ~ tpNoffsetl) wherein, "C" is the speed of light, " tp_{N et}i " i-^{s a PN} code offset specifically allocated to each base station and

" τ " is a correlation delay time of the first base station

BSl and the second base station BS2.

If the position of the mobile station, the positions of the first base station and the second base station are

represented as (x,y, z), ( x_x,y_λ,z^ and ( x₂,y₂,z₂) respectively, a measurement Equation for the distance will be expressed by

Equation 13. [Equation 13]

A = (^χ- ι)²⁺^-^ι)² +(^-^ι)² + ω = V(^χ - )² +(y- y₂f + 0 - ^z2? + a>2 wherein, the ω_λ is a first measurement error comprising a measurement error ω_mϊ and a NLOS error b_NLOS ,

and ω₂ is a total error including the first measurement

error ω_mX + b_NL0Sl and a second measurement error ω_m2 + b_NLOS2. A

3-dimentional position cannot be obtained since the number

of the measurement equation is only two. However, if an

altitude of the mobile station is known, Equation 14 can be

used.

[Equation 14]

x²+y²+z²=R²=(R ^te)²+Ab, wherein, Δb means a square of altitude error. Equation

14 includes an error of Δb because of the assumption that the altitude is already known. Equation 13 can be rewritten

as Equation 15.

[Equation 15]

Oi - ®ι)² = O - *ι)² + (y - yi + O - Zi)²

= R + Λj_j - 2(_Xlx + y,y + z_xz)

O2 - ^® ₂)² = (^x ~ ^xιΫ + (y^~ Vi + (^z - z₂)² = R_E ² + R_E ² ₂ - 2{x₂x + y₂y + z₂z)

wherein, " R^ " represents a distance from earth' s center to the i-th base station BSi, which includes no error

factor since exact positions for all base stations are known.

Equation 15 can be rewritten as Equation 16 by arranging x and y terms with respect to z.

[Equation 16]

^•7ι Rl+R_m ²-(p₁-ω_lf-2z₁z

X, R_E ² + R_E ² ₂-(P₂-c₂f ^■2z₂z

1 (y₂ - ι)(^RE + ^Rlι) - y₂(pι - ∞i? + ι(p₂ - «₂)² + ^te

2{x_ly_l-x₂y_l) _ (x, - x₂)(R_E ² + R_E ² ₁) + x₂(p₁ - ω + x{p₂ - ω₂f + 2z(x₂z,

Equation 16 may be simply rewritten as Equation 18 by

using coefficients defined as Equation 17.

[Equation 17]

_ foi ^~ *₂)(^RE + ^Rm) + ^x2 (A ^{~ Q}>i f + ^xι ( A ^~ <P₂)²

«„ =

2(x₁y_l-x₂y₁)

a. _ ^xι^z\ ~ \^z2) {xy₂-x₂y)

[Equation 18]

x = a_x+a_Λz y = a_y+a_s2z'

wherein, a_x and a include the measurement error and

the an altitude error. Equation 18 can be rewritten as Equation 19 in consideration of these error factors, [Equation 19] a_x = a "^e + Aa_r

a,. ^■■ a ^e + A „

_ _atrue 2{x₂p_xω_λ - x_xp₂ω₂) + x₂ω ² - x ω₂ + Δb(x, - x₂) ^y 2^ - ^)

A term "z" can be expressed by Equation 20 by substituting Equation 18 for Equation 14. [Equation 20]

Two solutions for the position of the mobile station can be obtained by substituting "z" term of Equation 20 for

Equation 18.

Use of at least three base stations

In case of using more than or equal to three base stations, the measurement equation for the distance will be expressed by Equation 21. [Equation 21]

A = (*^{~ x}ιY ⁺ - y ^{1 +} (^z - ^zιf + ^ωi> i=l,2,3,..., n, wherein, a subscript notation is an identifier for the base station. Equation 21 can be rewritten as Equation 22.

[Equation 22]

- 2x,x - 2y_ty - 2_∑iz = pf - R_E ² _i - R .

Equation 22 will be rewritten as Equation 23 by

applying to n numbers of satellites.

[Equation 23]

HX = R_a +R_ER_b , wherein, symbol "X" means a position to be determined, and "H", " R_β " and " R₆ " are expressed by Equation 24.

[Equation 24]

The position "X" can be finally determined by using

Equation 25,

[Equation 25]

X = (H^THy^lH^TR_a +Rl{H^THy^lH^TR_b .

The solution cannot be directly obtained from Equation

23 due to the known " R_π A quadratic equation, however, can be derived from Equation 14. And thus, two of the

navigation solutions can be determined by calculating two of

R_g by means of the quadratic equation and substituting it for Equation 25.

Therefore, the position of the mobile station can be determined in case of using more than or equal to two base stations, and an error range of the position may be determined in accordance with the measurement error after determining two of the navigation solution. However, the code search range can be further reduced by using at least two base stations since only gray region shown in Fig. 18 should be searched.

In accordance with the present invention, the volume of calculation in positioning procedure can be reduced and the receiving sensitivity can be improved since the

auxiliary information provided from the base station to the mobile station includes the navigation data. Therefore, the positioning procedure can be performed even inside a door

with low-intensity GPS signals. Furthermore, the code search range can also be reduced by means of the auxiliary information further including the cell coverage information of the base station. The GPS receiver and the positioning method in accordance with the present invention can be

widely applied not only to an emergency rescue service but also to an intelligent transportation system, a criminal tracking service, a cellular system design, a location-based billing and the like.

While the embodiments illustrated in the figures and described above are presently preferred, it should be understood that these embodiments are offered by way of example only. The invention is not limited to a particular embodiment, but extends to various modifications, combinations, and permutations that nevertheless fall within the scope and spirit of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A positioning method using a receiver for use in a

satellite positioning system for receiving auxiliary

information through a wireless communication network with at

least one base station and measuring a pseudo-range for each

of a plurality of satellites by means of the auxiliary

information, comprising the steps of :

(a) receiving GPS signals including a carrier, a

navigation data and a first pseudo noise code from each of a

plurality of the satellites, and generating an intermediate

frequency (IF) sampling signal by converting the GPS signals

into an IF bandwidth signals and sampling the IF bandwidth

signals;

(b) receiving the auxiliary information including a

time-tagged navigation data from the base station, and

generating a second pseudo noise code corresponding to the

first pseudo noise code;

(c) recovering the first pseudo noise code by

eliminating the navigation data by means of the time-tagged

navigation data from the IF sampling signals; and

(d) determining the pseudo-range by calculating a delay time of the first noise code on the basis of a

correlation value of the first pseudo noise code and the second pseudo noise code.

2. The method as claimed in claim 1, wherein step (d) including the steps of:

(dl) performing a coherent integration for the first pseudo noise code; and

(d2) calculating the delay time by performing a non- coherent integration for the second pseudo noise code and the integrated first pseudo noise code during a time interval longer than 20 miliseconds.

3. The method as claimed in claim 1 or claim 2, wherein the time-tagged navigation data in step (b) includes

the navigation data received by the base station and a signal receiving time at the base station, and step (c) including the steps of:

(cl) calculating a signal transmission time of the satellite by the equation as follow; and

(c2) eliminating the navigation data based on the signal transmission time, SVi

TZ = T_received -^ 'BS- r wherein, T™_s is the signal c transmission time of i-th satellite, T_received is the signal

receiving time at the base station and p_Bζ' /C is the pseudo- range between the i-th satellite and the base station.

4. The method as claimed in claim 3, wherein step (cl)

has the steps of:

(ell) calculating a bit phase for the base station by

means of the following equation (1),

BP_sn = fr{TZ /20msec} = BP + σ_BSclock ( 1 ) , wherein, σ_BSάock is an error occurred from the time

difference between the base station clock and the GPS

reference time and fr{} is a function calculating a value

below decimal point; and

(cl2) calculating a bit phase for the mobile station

by means of equation (2) ,

BP_MS = BP_BS -RTD + σ_BScl0Ck + σ_MSclock = BP_BS -RTD + σ_clock ( 2 ) ,

wherein, σ_clock presents a clock error of the mobile

station (MS) and the base station (BS) .

5. A positioning method using a receiver for use in a

satellite positioning system for receiving auxiliary information through a wireless communication network with at

least one signal transmission/receiving system and measuring

a pseudo-range for each of a plurality of the satellites by

means of the auxiliary information, comprising the steps

of :

(a) receiving GPS signals including a carrier, a

navigation data and a first pseudo noise code from each of a

plurality of the satellites, generating an intermediate

frequency (IF) sampling signal by converting the GPS signals

into IF bandwidth signals and sampling the IF bandwidth

signal, recovering the first pseudo noise from the IF

sampling signals, and generating a second pseudo noise code

corresponding to the first pseudo noise code;

(b) receiving pseudo-range information for the signal

transmission/receiving system, effective range information

representing a distance range between the signal

transmission/receiving system and the receiver; and

(c) determining the pseudo-range by calculating a

delay time of the first pseudo noise code on the basis of a

correlation value of the first pseudo noise code and the

second pseudo noise code,

wherein, in the procedure (c) , the receiver reduces a search range for use in calculating the correlation value by means of a pseudo-range information for the signal

transmission/receiving system and the effective range information and performs a correlation value calculation only for the reduced search range.

6. The method as claimed in claim 5, wherein step (c) includes the steps of:

(cl) establishing a searching reference point by means of the pseudo-range for the signal transmission/receiving system; and

(c2) determining the search range around the searching reference point by using the effective range information.

7. The method as claimed in claim 6, wherein the

signal transmission/receiving system is a base station in the wireless communication network;

the searching reference point in the procedure (cl) is calculated by equation (3) based on a pseudo-range p_BS for the base station,

T_PBS = fr{P_Bs _cA - )} (3), wherein, fr{} is a function calculating a value below decimal point, λ_CA is a wavelength of the C/A code and C is

the speed of light; and the search range for C/A code phase T_p in the

procedure (c2) is determined by equation (4) , T_PES ~ R_BS ∞<Θ_BS) - σ_clock ≤ _pm < T_Pas + R_BS ∞aψ_Bg) + σ_clock ( 4 ) , wherein, o_clock is a time synchronization error occurring between the base station and the receiver.

8. The method as claimed in claim 6, wherein the signal transmission/receiving system is a base station in the wireless communication network;

the searching reference point in the procedure (cl) is calculated by equation (5) based on a pseudo-range p_BS for the base station, T_pBs = fr{p_BS /(λ_CA - C)} (5),

wherein, fr{} is a function calculating a value below decimal point, λ_CA is a wavelength of the C/A code and C is

the speed of light; and the search range for C/A code phase T_p in the

procedure (c2) is determined by equation (6) ,

T_PBS ^~ R_RTD ∞ _BS) ~ & _doc ≤ T_PMS < T_PBS + R_RTD cos(0_B5) + σ_clock ( 6 ) , wherein, RTD represents a round trip delay (RTD) information between the base station and the receiver and

^σ _dock i-^{s a} time synchronization error occurring between the base station and the receiver.

9. The method as claimed in claim 6, wherein the

signal transmission/receiving system is a repeater with respect to a base station in the wireless communication network; the searching reference point in the procedure (cl) is calculated by equation (7) based on a pseudo-range p_Repeater for

the repeater,

^T ^_r = MP** peater t(λθl ^' Q) H) , wherein, fr{} is a function calculating a value below

decimal point, λ_CA is a wavelength of the C/A code and C is the speed of light; and the search range for C/A code phase T_PMS in the

procedure (c2) is determined by equation (8),

Ps_tfMi_r ~ RRa peater ^C0S "SB peater) ~ ° ^'clock - ^■*^■ p_m ( 8 ) ,

~ P_Kεpeax_r ⁺ RRB peater ^C0S(^Re peater) ⁺ ° ^'clock wherein, R_Rei7βater is an effective range of the repeater,

^_{pe ter} ^-^{s an} elevation angle of the satellite at the repeater and σ_chc is a time synchronization error occurring between the base station and the receiver.

10. A receiver for use in a satellite positioning system for receiving auxiliary information through a wireless communication network with at least one signal

transmission/receiving system and measuring a pseudo-range for each of a plurality of the satellites by means of the auxiliary information, comprising : a down converter for receiving GPS signals in radio

frequency bandwidth and down-converting the frequency bandwidth of the GPS signals to an intermediate frequency bandwidth by using local oscillation signals; an analog/digital converter for sampling intermediate frequency (IF) signals from the down converter by means of designated sampling clocks and outputting IF sampling

signals; a snapshot memory for storing the IF sampling signals; a digital signal processor for recovering a first pseudo noise code in the IF sampling signals by eliminating a navigation data included in the IF sampling signals by means of a time-tagged navigation data, for generating a second pseudo noise code corresponding to the first pseudo noise code, and for calculating the pseudo-range for each of a plurality of the satellites by calculating a delay time of

the first pseudo noise code on the basis of a correlation value of the first pseudo noise code and the second pseudo

noise code; a power controller for controlling a power supply to

the down converter, the analog/digital converter, the snapshot memory and the digital signal processor; and a control means for receiving the time-tagged navigation data through a modem, for providing the time- tagged navigation data for the digital signal processor, and

for controlling the power controller.

11. The receiver as claimed in claim 10, wherein the receiver further comprises a frequency synthesizer for generating the local oscillation signals and the sampling

clocks by means of predetermined reference clock, wherein the frequency synthesizer shares the reference clock with

the control means.

12. A receiver for use in a satellite positioning system for receiving auxiliary information through a wireless communication network with at least one signal transmission/receiving system and measuring a pseudo-range

for each of a plurality of the satellites by means of the auxiliary information, comprising :

a down converter for receiving GPS signals in radio frequency bandwidth and down-converting the frequency

bandwidth of the GPS signals to an intermediate frequency bandwidth by using local oscillation signals;

an analog/digital converter for sampling intermediate frequency (IF) signals from the down converter by means of designated sampling clocks and outputting IF sampling signals; a snapshot memory for storing the IF sampling signals; a digital signal processor for recovering a first pseudo noise code in the IF sampling signals, for generating a second pseudo noise code corresponding to the first pseudo

noise code, and for calculating the pseudo-range for each of a plurality of the satellites by calculating a delay time of the first pseudo noise code on the basis of a correlation value of the first pseudo noise code and the second pseudo noise code;

a power controller for controlling a power supply to the down converter, the analog/digital converter, the snapshot memory and the digital signal processor; and

a control means for receiving pseudo-range information for the signal transmission/receiving system and time-tagged

effective range information representing a distance range between the signal transmission/receiving system and the receiver from the signal transmission/receiving system by way of a modem, for providing the pseudo-rnage information and the time-tagged effective range information for the digital signal processor, and for controlling the power controller,

wherein, the digital signal processor reduces a search range for use in calculating the correlation value by means of the pseudo-range for the signal transmission/receiving system and the effective range information, and performs the correlation value calculation only for the reduced search

range .

13. The receiver as claimed in claim 12, wherein the

receiver further comprises a frequency synthesizer for generating the local oscillation signals and the sampling clocks by means of predetermined reference clock, wherein, the frequency synthesizer shares the reference clock with the control means.