MXPA99011587A - Location system lo - Google Patents

Abstract

The present invention relates to a local location system (LPS) that uses the radio propagation parameters in a CDMA forward link or TDMA reverse link to establish the position of a mobile station. The mobile station receives pilot channel signals from at least three different base stations and records the displacement of PN chips from the pilot channel signals. The difference in LPS time of the arrival triangulation approach requires additional serial detection capabilities. The base stations send pilot channel signals arriving in a mobile station with a particular phase and at least a predetermined minimum intensity. The mobile station reports back the "visible" pilot channel signals, their phases, and the serial strength to the LPS using a nonlinear location system is expressed with a set of cost functions to estimate the location of the mobile. The LPS can also solve the 9-1-1 mobile location problem for wireless CDMA systems by determining the position of a person requiring assistance, who has a digitized cell phone.

Description

LOCAL LOCATION SYSTEM Field of the Invention The present invention relates to determining the position of a mobile station; more specifically, to locate a mobile station using different arrival times (TDOA = Time- Difference of Arrival). Description of the Related Art A positioning system or global location (GPS = global positioning system) is commonly used to provide a receiver with precise measurements of its location. The GPS receiver obtains the signal from satellites and determines their positions when performing TDOA calculations based on the known position of the satellites. The receiver is generally connected to a vehicle or vessel and is provided for this sole purpose. The expense of GPS receivers generally limited their buyers to owners of luxury vehicles, craft aircraft. Digital cell phones / PCS, have become a very convenient and economical way for a person to communicate with others or communicate systems where the person is located. The person can also call 9-1-1 in the case of an emergency. However, to date, the wireless communication systems do not determine from REF: 32031 precisely the location of the calling subscriber, without the use of satellite and GPS. Current wireless communications systems use multiple access techniques to combine signals to different sources to allow many users to share a common medium without mutual interference. One of the basic types of multiple access techniques is multiple access with code division (CDMA = Code Multiple Division Access). In CDMA, for each base station transmits a pilot channel signal, which is essentially a non-modulated pseudorandom (PN) interference sequence. The PN sequence comprises a sequence of flakes or PN chips, and each PN flake corresponds to a distance of approximately 243.96 meters (800.4 feet). Each base station transmits the pilot channel signal using a different synchronization offset, such that the mobile stations can distinguish from which base station a pilot channel signal was transmitted. The mobile station is synchronized in time with a service base station, i.e. the base station where the mobile station is in communication. The mobile station searches for time intervals referred to as search windows for the pilot channel signals. Each base station is configured to transmit its pilot channel signal, so that mobile stations can expect to start receiving no more than one pilot channel signal with each search window. When the mobile station detects a pilot channel signal, it measures the pilot channel signal strength and records the phase of the pilot channel signal, in terms of flakes or PN chips, as the pilot channel signal reaches the mobile station. If the pilot channel signal strength exceeds a predetermined threshold, then the base station transmitting the pilot channel signal is "visible" to the mobile station. The measurements and registers are transmitted from the mobile station to the service base station or some other pre-determined location on a reverse sense link. Conventional methods for determining the geolocation of a mobile station generally provide an indication of distances between at least three "visible" base stations and the mobile station. The distance between a base station and a mobile station is equal to time? T ± for a signal to travel from the base station to the mobile station, multiplied by a wave speed v of the signal. If At v is a distance from the mobile station (which has geographic coordinates (?? 'i)) to a first base station (having known coordinates (x1, y1)),? t2 v is a distance from the mobile station to a second base station (having known geographic coordinates (x2, y2) ) and distance? t from the mobile station to a third base STA (which has known coordinates) (x3, y3)), hence K in the Pythagorean theorem, the following equations derived from a time-of-arrival approach ( TOA): ? /, v = .x - x ") 2 + (v, -?"); 1 ? V - ^? -, -J: ,,) 2 + (V. - ") :. to determine the moving position (x0, y0). However, in CDMA, time? T, is unknown because mobile stations do not have absolute time reference to measure? T ... A TDOA approach reduces the number of equations from three to two (equation (3) minus equation (1) and equation (2) minus equation (1)). The TDOA approach provides accurate location determinations if there are no present system measurement errors or multiple patch effects, described below. Unfortunately, there are in general errors of system measurement and effects of multiple trajectories and cause deviations from real location determinations. Therefore, the above equations can not be used directly to accurately determine the geolocation of M's of the mobile station. COMPENDIUM OF THE INVENTION The present invention addresses these problems by providing a local location system (LPS = Local Positioning System) designed to use radio preparation parameters in multiple access outbound links with code division (CDMA = Multiple Code-Division). Access), multiple-access reverse access links with time division (TDMA = Time-Division Multiple Access) to estimate the position of a mobile station. The LPS determines the position of the mobile using triangulation methods by minimizing two sets of equations called cost functions. The first set of cost functions represents distance errors from the "visible" base stations to the mobile station, and the second set of cost functions represents position errors in the location estimate of the mobile station. Both sets of cost functions include variables common to more than one and the cost functions within the set. Cost functions are minimized by estimating values for unknown variables within each equation, so that distance or position errors in the set are as close to zero as possible.

To determine the geographic coordinates of a mobile station when the distances between the mobile station and the base stations are unknown, the LPS first estimates the distance from the mobile station to the base stations to mitigate system measurement errors and the effect of multiple trajectories After the distances are estimated, the LPS estimates the geographic coordinates of the mobile station (x0, y0), based on the estimated distances. In a preferred embodiment, the LPS is a software (software) implementation and a computer to determine the geographic location (geolocation) of the mobile station. The LPS receives a data sample including information indicating arrival times of pilot channel signals in a mobile station and accesses base station information indicating the location of at least three PCS or cellular base stations to which the arrival time information Is associated. The LPS then estimates the distances from the mobile station to the base stations by minimizing a first set of equations or cost functions and estimates the geolocation of the mobile station by minimizing a second set of equations or cost functions based on the estimated distances .

The LPS of the present invention provides the benefit of using existing equipment to provide GPS-like location capabilities. The LPS does not require additional signal detection capabilities, and requires only minor modification to existing wireless telephony systems. No additional physical equipment is required apart from the standard CDMA / TDMA system, making the LPS effective in cost. The LPS can also solve the 9-1-1 mobile location problem for wireless CDMA / TDMA systems. Therefore, the LPS from your digital phone, can determine the position of a person who needs help. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in detail with reference to the following drawings in which like numbers represent similar elements and: Figure 1 illustrates a mobile station located within a triangle formed by three distinct base stations; Figure 2 illustrates a mobile station located outside a triangle formed by three different base stations; Figure 3a is a schematic perspective view of the implementation of LPS according to a preferred embodiment of the invention; Figure 3b is a schematic perspective view of the implementation of LPS according to another preferred embodiment of the invention, - and Figure 4 illustrates a flow chart of a preferred embodiment of the LPS, - Figure 5 is a diagram illustrating an exemplary performance analysis of the LPS. DETAILED DESCRIPTION OF THE INVENTION The modalities described herein are used in a forward link triangulation (FLP = Forward Link Triangulation) CDMA system. It is understood that the modalities also apply to a reverse link triangulation system (RLT = Reverse Link Triangulation) TDMA before synchronization of the baee stations. The LPS determines the geographical coordinates of the mobile station upon receiving a data sample representing information regarding the mobile station, accessing information from the base station with respect to at least three base stations and estimating the location of the mobile station. The LPS determines the location of the mobile station by minimizing a first set of equations or cost functions, to estimate the distances between the mobile station and the base stations, based on the data sample and the base station information, and then minimize a second set of equations or cost functions to estimate the geographical coordinates of the mobile eetation. The LPS is based on TDOA that uses chip shift information or measured phase shift of the pilot channel signals that are transmitted from particular base stations that are "visible" to the mobile station. A TDOA triangulation approach requires propagation delay measurement or time of at least three "visible" base stations. If less than three base stations are "visible" to the mobile station, then the LPS will wait for a mobile station report from three "visible" base stations or adjust the signal strength threshold levels to allow the mobile to recognize more signals from the mobile station. pilot channel of other stations baee. The mobile station often measures the pilot channel signal phases, so that the location estimate can be increased and made more accurate over time. Figure 1 shows a point representing the mobile station N located within a triangle of points representing "visible" base stations b1, b2 and b3 at respective distances dl r d2 and d3 from the mobile station M. The distances between the stations base are measured as: length bx, b2 between the base stations b1 and b2; length h? , b3 between the base stations hx and b3; and length b2, b3 between the base stations b2 and b3. Angles c-12, -13 and a; 23 are formed by the arcs bxMb2, B1Mb3 and B2Mb3 respectively. In Figure 1, the angles a23 is equal to 360 ° minus the angle a12 and a-13. Figure 2 is similar to Figure 1 except that mobile station N is located outside triangle b, b2 and b3 and angle a23 is equal to angles C-12 + 0i3 • Figure 3a illustrates a diagram of an implementation of LPS alternates. The LPS 1 includes a computer 10 and an article of manufacture 20 and can be located in one of the base stations. The article of manufacture 20 includes a computer-readable medium and an executable program for locating the mobile station M. Figure 3b illustrates an alternate LPS implementation. The LPS includes the computer 10 to receive a signal 30 that carries the executable program to locate the mobile station M. The signal 30 is transmitted in a digital format with or without a carrier wave. Figure 4 illustrates a flow diagram of LPS for locating the mobile station M in a preferred embodiment. In step S10, the LPS 1 reads data entry samples (for example) sector number, pilot phase and intensity of the pilot channel signal (from the mobile station M). In step S20, the LPS 1 reads a table of cell sites that includes information such as the base station ID, sector numbers of the base stations and the geographic location of the base stations, measures for example in altitude and length. In step S30, the sector numbers of the data samples are mapped to those in the cell site table to determine from where the pilot channel signals originate. If the pilot channel signals are of at least three base stations, then the triangle of blb2b3 is formed as illustrated in Figures 1 or 2 and the distances between the mobile section M and the base stations b1, b2 and b3 and the geolocation of the mobile station M can be determined. The distances between the mobile station M and the selections baee visible b1 # b2 and b3 are estimated in step S40. The computer 10 calculates by distance d such that a set of cost functions for distance errors are minimized and determine distance d2 and d3 based on the clear distance d. The estimate of the distance d ± and the determination of the distances d2 and d3 based on the distance d1 will be described below. The LPS determines the geographic coordinates of the mobile station M in S50 using TDOA. The LPS 1 calculates the local coordinates of the mobile station M, ie (x0, y0) in relation to the service base station h, and converts the local coordinates (x0, y0) to latitude and longitude, based on the altitudes and known lengths of base stations b1 # b2 and b3. When there are successive measurements and recordings of pilot channel phase, the geolocation of the mobile station M can be re-estimated and averaged, to provide an even more accurate analysis. Step S40-estimate distances between the mobile station and the base stations. The two most critical system measurement errors in a TDOA approach are rounding errors in the pilot channel signal phase measurement and synchronization errors between the base stations. For the measurement of pilot channel signal phase, if a chip corresponds to 243.96 m (800.4 feet), then the rounding error (worst case half of chip) contributes to 121.98 meters (400.2 feet) in deviation from the location. The rounding error can be represented by the random variable x when it satisfies a uniform distribution. Ideally, each base station is synchronized in time with the other base stations.

-Each base station can also be synchronized in time using a GPS clock. However, current clocks in base stations tend to move around a nominal value. The displacement error can be represented as a random variable T2, which satisfies another uniform distribution. The influence of the error sources can be added to the same measurement error of system T, which is the sum of random variables T1 + T2.

Accordingly, a measured pilot channel signal phase p ± is equal to a real pilot channel signal phase plus a system measurement error T. TDOA works best if the measurements "used are those that belong to the signals line-of-sight (LOS = Line-Of-Sight) because a straight line is the shortest line between two points Unfortunately, it is not always possible for mobile station M to receive the LOS signals from the base stations bl; b2 and b3 A single transmitted signal from any of the base stations b-_, b2 and b3 can be reflected from different objects such as buildings, trees and vehicles before it reaches the mobile station M and therefore has a longer trajectory than If the signal was a LOS signal, this effect of multiple trajectories causes a delay in the arrival of the signal and affects the TDOA estimate in a harmful way, since there is no guarantee that a mobile station M will acquire d-line signals. e-vision (LOS) of the visible base stations b1; b2 and b3, the arrival time delay caused by a multipath signal must be taken into account when using TDOA to determine the distance between the mobile station M and the stations lo-,, b2 and b3. However, the amount of delay differs depending on the distance and the objects located between the mobile station M and the base stations bx, b2 and b3 and therefore it is very difficult to model. Accordingly, a simple multipath parameter μ represents the proportional time delay caused by the effect of multiple trajectories and is modeled as a non-random parameter instead of a random number because the simple multipath parameter μ must estimate for all pilot channel signals. The multipath parameter μ in general is less than one, and will equal its maximum one if the mobile station M only acquires LOS signals from the visible base stations b-L, b2 and b3. It should be noted that a single multipath parameter μ is considered to imply a homogeneous multipath effect. That is, the delay caused by the effect of multiple paths is considered to be the same for each pilot channel signal even when the effect of multiple paths in the pilot channel signal of each of the base stations bx, b2 and b3 is different. A multi-trajectory parameter μ representing a uniform extra delay can substantially alleviate the effect of multiple trajectories. The parameter of multiple trajectories μ can be varied in a certain range defined by a model associated with typical environments such rural, urban, sub-urban, road, etc.

The mobile station M does not know the exact time (synchronized with GPS) that the base station b ± transmits a pilot channel signal measures the exact time that station M receives the pilot channel signal in order to determine the time it takes for the pilot channel signal to travel from station b To the mobile station M. Therefore, the distances d- ^, d2 and d3 between the base stations bj_ and the mobile station M are unknown. However, the base stations are synchronized with each other and the mobile station M is synchronized with the service base station h1. In this way, the mobile station can record chip shifts of the pilot channel signal phases emitted from remote base stations b2 and b3 in relation to the pilot channel signals of the service base station bx. Thus, the mobile M can determine the actional time after receiving the pilot channel signal from the base service station ^ -required so that the pilot channel signals travel from the remote base stations b2 and b3 to the mobile station M because the phase of the remote base stations b2 and b3 is measurable in relation to the fae of the service base station b ~ ±, which is set to zero due to the synchronization of the mobile station M with the base station b-,. The mobile station M identifies a pilot channel signal phase P2 as a difference in phase between the pilot channel signal phase registers of the base stations bx and b2 identifies a pilot channel signal phase P3 as a phase difference between The record of the pilot channel signal is recorded from base stations b1 and b3. According to this, the distance d2 equals the distance d? plus 243.96 meters (800.4 feet) for the pilot channel signal faee p2 or d2 = d? + 800.4 (p2) ft (4) Similarly, the distance d3 equals the distance d ± plus 243.96 meters (800.4 feet) for the pilot phase p3, or 13 = d + 800.4 p3 ft (5) However, the distance d-i must be estimated before the distances d2 and d3 can be determined. Consequently, LPS 1 estimates the distance dx. To find an estimate by distance d, the following equations (6) - (8) are cost functions that are minimized for distance errors F12, F13, and F23: F12 (b b2) 2 - μ2d? 2 - μ2d22 + 2μ2 (d1) (d2) cos 12, (6) i3- = (b? bs < 2 ~ ß2?? 2 '-2 ^ 32 + 2μ2 (d2) (d3) coso? 13, (7) F23 = ( b2b3 '- - μ, - .-- V- - + 2μ (d2) (d3) cosc¿23 (8) for the distance dlf parameters of multi-trajectories μ and angles ce, and substituting for distances d2 and d3 Based on equations (4) and (5), the cost functions for distance errors F12, F13 and F23 should be minimized to arrive at the best estimate for distance d2.The minimization of cost function F12, F13, and F23 can be achieved using well-known minimization approaches, such as steeper incremental or diminished search with respect to ad? For example, using an incremental search approach, the above cost functions can be minimized by estimating a range for distance ia d and the multipath parameter μ, solving the equations (6) - (8) for each predetermined increment in the ranges and selecting the distance dl f multiple trajectory parameter μ and angles a12, a13 and c-23, which provide the distance errors F12, F13 and F23 closest to zero . After the distance d is estimated, the distance d2 and d3 can be determined using equations (4) and (5). Equations (6) - (8) have 4 unknown values, ie the distance d1 # the multipath parameter μ, and the angles of12 ai3 • As discussed above, the angle a-23 is equal to 360 degrees minus the angles a-12 and a-13 when the mobile station M is located within the triangle b1b2b3. The angle a-23 is equal to the angles a.12 plus a.13 when the mobile station M is located outside the triangle b1b2b3. However, the angles c-12 and of13 are determined based on the estimated distance d-_, in other words the values of the angles a-12 and c¿13 are determined according to the value of the distance d? . A person with dexterity in the field will readily understand that the CDMA (and TDMA) systems can measure a round trip delay of a pilot channel signal that is emitted from the service base station bx to the mobile station M and back to the base service station bL. This round trip delay provides the benefit of allowing the LSP 1 to use a narrower range to estimate the distance range. Step S50 - Determine the mobile station's location After the distance d, 22 and 33 have been estimated, then the Cartesian coordinates (x0, yQ) of the mobile station M can be estimated by minimizing the equations (9) - (11) for function of coefficient G1, G2 and G3: G2 = μ2 (d) 2 ~ [(x? - x0) 2 + (Yi ~ Yo) 2] O) G2 = μ2 (d2) 2 - [(x2 - x0) 2 + (y2 - y0) 2] (10) G3 = μ2 (d3) 2 - [(x3 -? 0) 2 + (y3 - y0) 2] (11) where G¿, i = 1 , 2, and 3 repreeentan the error of poetry and is zero in an ideal case. However, since the distances dx, d2 and d3 are estimated, equations (7-9) will not be resolved exactly but the best estimate of (x0, y0) can be found by minimizing G ±. Estimation and Coordinate Conversion Example The mobile station M is synchronized with the parking station. In the mobile station M, the reeppette maneuver sent back to the base station bx, the phase displacement of the reference pilot channel signal transmitted by the base station bx is set to zero. The pilot channel signal phases of the base stations b2 and b3 are recorded in chip offsets, from zero phase shift of the base station b1. According to this, once the distance b-L is estimated, the distance d2 and d3 can directly determine as discussed previously. According to the SIO and S20 stages of the Figure 4, the LPS 1 gathers power information including information of the mobile station M and information of the base station h- ^ b2 and b3. For example, the mobile station M records pilot channel emitted from the base station b1 with a base station identifying the PN pilot of 432, and a pilot channel signal intensity of 17 (-8.5 dB); from the base station b2, with a base station identifying the PN pilot of 76, a pilot channel signal phase p2 equal to 4 PN chips, and a pilot channel signal intensity of 21 (-10.5 dB); and from the base station b3, with a base station identifying the PN pilot of 220, a pilot channel signal phase p2 equal to 3 PN chips, and a pilot channel signal intensity of 19 (-9.5 dB). According to step S30 of Figure 4, the pilot PNs that are reported by the mobile station M, are coupled with the pilot PNs in the sector information stored in a cell site table, to determine from which stations base bl t b2 and b3 the pilot channel signals were sent. Here, the base station b is the cell number 138 transmitting a pilot PN of 432 and is located at latitude 40.861389 and longitude -73.864167; base station b2 is cell number 140, which transmits a pilot PN of 76 and is located at latitude 40.867500 and longitude -73.884722; and the base station b3 is the cell number 43, which transmits a pilot PN of 220 and is located at latitude 40.878889 and longitude -73.871389. Altitudes and base station lengths become a seventh of local coordinates (x, y). The coordinates of the station baee b-, (0,0) are set as the origin, the coordinates of the base station b2 (x2,0) are adjusted on the X axis and the coordinates of the base station b3 (x3, y3 ), are determined from the known distances between the base eetations. According to step S40 of Figure 4, the cost function equations (6) - (8) are then minimized to estimate that the distance d equals 1,289 km (.801 mile) the multipath parameter μ equal to 0.98, angle ar12 = 1.784084 radial, angle a13 = 3.002281 radial and angle a23 = 1.218859 radial. Based on the estimated distance d-L, the distances d2 and d3 are determined directly as previously determined equal 1.5826 km (0.983620 miles) and 1.351 km (0.839603 miles), respectively. Agree. with step S50 of Figure 4, the equations (9) - (11) are then minimized to determine that the local Cartesian coordinates (x0, y0) equal to (0.237018, 0.357580). These coordinates can be converted back to latitude and longitude, so that the location of the mobile station M's can be more easily marked on a map to show which street is Libyan. In this example, the local Cartesian coordinates (0.237018, 0.357580) of the geographic location of the mobile station M's are converted to latitude 40.867465 and longitude -73.865885. In the previous example, the angle a 3 is equal to angle a12 plus the angle a23. Therefore, the mobile station M is not located within the triangle b1b2b3, but instead lies outside the length bxb3. Estimated Distance Deviation The lower line in Figure 5 shows an example of distance deviation (ft) between the actual location and the estimated LPS location of the mobile station M, based on the time deviation (μs) caused by system measurement errors, including rounding errors in the measurement of pilot channel signal phase and synchronization errors. The upper line represents the maximum error for performance over a time snapshot. If one is extended over time and averages of diet are averaged, distance deviation will become the lower or lower average error line. Accordingly, if the base stations are synchronized, the rounding error in the pilot channel signal phase measurement is only about 60.96 meters (200 feet). Reverse Link Triangulation (RLT) In the American TDMA sevenmas, the arrival of time is obtained in the base stations instead of the mobile stations. The mobile station transmits a color code signal with coded digital verification (CDVCC = Coded Digital Verification Color Code) as the identity of the mobile station. Upon receiving the CDVCC signal, the receiving base station sets a date stamp at the time of receiving the CDVCC signal. If the base stations are synchronized, then the base stations determine the relative time differences between the arrival of the CDVCC signal by evacuating the signal receiving time at the first base station of the time of the last signals received at the other base stations . Accordingly, the LPS applies to both CDMA and TDMA systems. Therefore, equations (6) - (11) can also be applied to TDMA RLT geolocation systems if the clock signals or base stations involved in locating a particular mobile station are synchronized. The synchronization can be done by GPS installation. Reverse direction link signals are transmitted from the mobile stations to the base stations through the reverse direction link, which is generally a frequency band different from the forward link of the CDMA systems, but in the same frequency band and different time slots for TDMA system. A TDMA inverse link provides the benefits of better location accuracy if the time arrival is measured at the base stations because there would be no chip rounding error as in the CDMA outbound link. In addition, the control of power in CDMA is not as strict as in CDMA, therefore it is easier for several base stations to "see" the signals of the mobile. Feeds required by the reverse link triangulation of TDMA include the identity of the mobile requesting the location service, the relative time arrivals at the base stations, location (latitude / longitude) of all the base station and the travel delay round (continuously measured in TDMA for time alignment purposes). The inteneity of the signal from the mobile station is also desired and can be measured at the neighboring base stations for transfer assistance. While this invention has been described in conjunction with specific embodiments thereof, it is evident that various alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, preferred embodiments of the invention as set forth herein are intended to be non-limiting illustrative. Various changes can be made without departing from the spirit and scope of the invention as defined in the following claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (29)

1. CLAIMS Having described the invention as above, C? ID μ-r-erfrr-3o t-il-tjiidb is claimed in the following: 1.- Method to determine the position of a mobile station, characterized in that it comprises the steps of: a) receiving pilot channel signal information indicating times of arrival of pilot channel signals in the mobile station; and b) estimating the location of the station by minimizing a set of position error cost functions, based on the pilot channel signal information and base station information indicating the location of a plurality of base stations to which the station is located. they associate the arrival times.
2. 2 . - The method according to claim 1, characterized in that the position error cost functions are derived from the equations: G2 = μ (dz) 2 - i (? -? 0) 2 + (y - y0) 2l G2 = μ2 (d2) 2 - [(x2 - x0) 2 + (y2 - y0) 2] G3 = μ2 (d3) 2 - [(x3 - x0) 2 + (y3 - y0) 2] where μ is a multi-path effect parameter, dx is a distance from the mobile station to the first base station, d2 is a distance from the mobile station to the second station baee, d3 is a distance from the mobile station to the third base station, ( x0, y0) are the local Cartesian coordinates of the mobile station, (x1 # and x) are the local Cartesian coordinates of the first base station (x2, y2) are the local Cartesian coordinates of the second mobile station y (x3, y3) they are the local Cartesian coordinates of the third mobile station.
3. 3. - The method according to claim 2, characterized in that d? = d. + 800.4 (p) ft, where p? is a phase difference between the pilot channel signal phase registers of the first and second base stations, and d, = d, + 800.4 (p-) ft, where p3 is a phase difference between the pilot channel signal phase registers of the first and third base stations.
4. 4. - The method according to claim 1, characterized in that antee of the stage - (b) further comprises the steps of: (c) receiving the base station information indicating the location of the plurality of base stations; and (d) adjusting the pilot channel signal information to the base station information, based on a common source identifier for both the pilot channel signal information and the base station information.
5. 5. - The method according to claim 1, characterized in that the arrival time correspond to the synchronized time of the base station.
6. 6. The method according to claim 1, characterized in that before step (b), further comprises the steps of: (e) estimating a distance from the mobile station to one of the base stations by minimizing a set of functions of cost of error of distance, including angles formed by the parking baee and the mobile eetation.
7. 7. - The method according to claim 6, characterized in that the cost functions of error in distance are derived from the equations: F12 (b1b2) 2 - μ2d 2 - μ2d22 + 2μ2 (d?) (D2) coso¿12 , F13 = (b? B3) 2 - μ2d 2 - μ2d32_ + _ 2μ2 (d ±) (d3) coso? 13, F23 = (b2b3) 2 - μ2d22 - μ2d32 + 2μ2 (d2) (d3) thing > 23 where b-_b2 is a diet from the first base station to the second base station, b -] _ b3 is a distance from the first base station to the third base station, b2b3 is a distance from the second base station to the third base station base station, μ is a parameter of effects of multiple trajectories d? is a distance from the mobile station to the first base station, d2 is a distance from the mobile station to the second base station, d3 is a distance from the mobile station to the third base station, a12 denotes the angle formed by the lines between the mobile station and the first and second base stations, a- 3 denotes the angle formed by the line between the mobile station and the first and third base stations and a-23 denotes the angle formed with the lines between the mobile station and the second and third base station.
8. 8. - The method according to claim 1, characterized in that the pilot channel signal information includes at least one of a source identifier, a pilot channel signal phase and a pilot strength or intensity.
9. 9. - The method according to claim 8, characterized in that the station information baee includes at least one of the source identifier and the base station location.
10. 10. - The method according to claim 1, characterized in that it also comprises the step of averaging the estimation of the location of mobile station with a previous estimate of the mobile station, to acquire an average estimate of the location of mobile station.
11. 11. - The method according to claim 1, characterized in that the pilot channel signal information is included in a CDMA signal.
12. 12. - The method according to claim 1, characterized in that the pilot channel signal information is included in a TDMA signal.
13. 13. - A local location system implemented in a computer to determine the position of a mobile station, characterized in that it comprises: means for receiving pilot channel signal information indicating times of arrival of the pilot channel signals in the mobile station; and means for estimating the location of the mobile station by minimizing a set of error-in-position functions, based on pilot channel signal information and baee station information indicating the location of a plurality of base etitions to which the arrival times are associated.
14. 14. The local location system according to claim 13, characterized in that the functions of error cost in position are derived from the equations Gi = μ2 (dx) 2 - [(? -? 0) 2 + (Ai - y0) 2V G2 = μ2 (d2) 2 - [(x2 - x0) 2 + (y2 - y0) 2], G3 = μ2 (d3) 2 - i (x3 - x0) 2 + (y3 - yQ) 2] where μ is a multiplex path effect parameter, dx is a distance from the mobile station to the first base station, d2 is a distance from the mobile station to the second base station, d3 is a distance from the mobile station to the third station baee, (x0, y0) eon the local Cartesian coordinates of the mobile station, (x1, yx) are the local Cartesian coordinates of the first base station (x2, y2) are the local Cartesian coordinates of the second mobile station and (x3, y3) are the local Carteeianae coordinates of the third mobile eetation.
15. 15. - The local location system according to claim 14, characterized in that d? = d, + 800.4 (P2) ft- where p "is a difference of fae between the signal registers of the pilot channel signal of the first and second station bases, and or d = 1 + 800.4 () ft "where p3 is a phase difference between the phase registers of the pilot channel signal of the first and third base stations.
16. 16. The local location system according to claim 13, characterized in that before the means for estimating the location of the mobile station, it also comprises means for receiving the base station information indicating the location of the plurality of base stations, - and means for matching the pilot channel signal information with the base station information, based on a common source identifier to both the pilot channel signal information and the base station information.
17. 17. - The local location system according to claim 13, characterized in that the arrival times correspond to the synchronized times of the base stations.
18. 18. - The local location system according to claim 13, characterized in that before the means to determine the location of the mobile station, it further comprises: means for estimating a distance from the mobile station to one of the base stations, minimize a set of distance error cost functions including angles formed by the base stations and the mobile station.
19. 19. - The local location sevenma according to claim 18, characterized in that the functions of error coefficient in diet ee derive from the equations: F12 (b? B2) 2 - μ2dx2 - μ2d22 + 2μ2 (dx) (d2) COSOL12, F13 = (b2b3) 2 - μ2dx2 - μ2d32 + 2μ2 (d2) (d3) cosc13, F23 = Cjb2-b-3 ') 2"μ2d22 - μ2d32 + 2μ2 (d2) (d3) coso? 23 in where b ^ -, is a distance from the first base station to the second base station, bxb3 is a diet from the first base station to the third base station, b2b3 is a distance from the second base station to the third base station, μ is a multi-path effect parameter d? is a diet from the mobile station to the first base station, d2 is a distance from the mobile station to the second base station, d3 is a distance from the mobile station to the third station baee, - a-12 denotes the angle formed by the line between the mobile station and the first and second stations baee, a13 denotes the angle formed by the line between the mobile station and the first and third base stations and 23 denotes the angle formed with the lines between the mobile station and the second and third base stations.
20. 20. The local location system according to claim 13, characterized in that the pilot channel signal information includes at least one of a source identifier, a pilot channel signal phase and a pilot force or intensity.
21. 21. The local location system according to claim 20, characterized in that the base eetation information includes at least one of the source identifier and the base station location.
22. 22. - The local location system according to claim 13, characterized in that it also comprises means for averaging the estimation of the mobile station location with a previous estimate of the mobile station to acquire an average estimate of the mobile station location.
23. 23. - The local location system according to claim 13, characterized in that the pilot channel signal information is included in a CDMA signal.
24. 24. The local location system according to claim 13, characterized in that the pilot channel signal information is included in a TDMA signal.
25. 25. An executable program incorporated in a computer-readable medium for determining the position of a mobile station, characterized in that it comprises a segment of source code receiving to receive pilot channel signal information indicating times of arrival of the pilot channel signals in the mobile station; and an estimated source code segment for the location of the mobile station by minimizing a set of error cost functions in position with baee in the pilot channel signal information and the base station information indicating the location of a plurality of base station to which arrival times are associated.
26. 26. The executable program according to claim 25, characterized in that it further comprises: a computational source code segment for estimating a distance from the mobile station to one of the base stations by minimizing a set of error cost functions in distance including angles formed by the base stations and the mobile station.
27. 27.- A computer data signal, characterized in that it comprises: a receiver signal segment for receiving the pilot channel signal information indicating times of arrival of pilot channel signals in the mobile station; and an estimation signal segment, for estimating the location of the mobile station by minimizing a set of error cost functions in position, based on the pilot channel signal information and the base station information indicating the location of the a plurality of base stations in which the arrival times are associated.
28. 28. The computer data signal according to claim 27, characterized in that it further comprises: a computation signal segment for estimating a distance from the mobile station to a base station by minimizing a set of error cost functions in distance including angles formed by the base stations and the mobile station.
29. 29. - The computer data signal according to claim 27, characterized in that the computer data signal is incorporated into a carrier wave.